1 | /* vi: set sw=4 ts=4: */
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2 | /*
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3 | * udhcp client
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4 | *
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5 | * Russ Dill <Russ.Dill@asu.edu> July 2001
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6 | *
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7 | * This program is free software; you can redistribute it and/or modify
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8 | * it under the terms of the GNU General Public License as published by
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9 | * the Free Software Foundation; either version 2 of the License, or
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10 | * (at your option) any later version.
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11 | *
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12 | * This program is distributed in the hope that it will be useful,
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13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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15 | * GNU General Public License for more details.
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16 | *
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17 | * You should have received a copy of the GNU General Public License
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18 | * along with this program; if not, write to the Free Software
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19 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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20 | */
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21 | #include <syslog.h>
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22 | /* Override ENABLE_FEATURE_PIDFILE - ifupdown needs our pidfile to always exist */
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23 | #define WANT_PIDFILE 1
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24 | #include "common.h"
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25 | #include "dhcpd.h"
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26 | #include "dhcpc.h"
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27 |
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28 | #include <netinet/if_ether.h>
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29 | #include <linux/filter.h>
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30 | #include <linux/if_packet.h>
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31 |
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32 | /* "struct client_config_t client_config" is in bb_common_bufsiz1 */
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33 |
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34 |
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35 | #if ENABLE_LONG_OPTS
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36 | static const char udhcpc_longopts[] ALIGN1 =
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37 | "clientid-none\0" No_argument "C"
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38 | "vendorclass\0" Required_argument "V"
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39 | "hostname\0" Required_argument "H"
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40 | "fqdn\0" Required_argument "F"
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41 | "interface\0" Required_argument "i"
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42 | "now\0" No_argument "n"
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43 | "pidfile\0" Required_argument "p"
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44 | "quit\0" No_argument "q"
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45 | "release\0" No_argument "R"
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46 | "request\0" Required_argument "r"
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47 | "script\0" Required_argument "s"
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48 | "timeout\0" Required_argument "T"
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49 | "retries\0" Required_argument "t"
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50 | "tryagain\0" Required_argument "A"
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51 | "syslog\0" No_argument "S"
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52 | "request-option\0" Required_argument "O"
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53 | "no-default-options\0" No_argument "o"
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54 | "foreground\0" No_argument "f"
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55 | "background\0" No_argument "b"
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56 | "broadcast\0" No_argument "B"
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57 | IF_FEATURE_UDHCPC_ARPING("arping\0" No_argument "a")
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58 | IF_FEATURE_UDHCP_PORT("client-port\0" Required_argument "P")
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59 | ;
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60 | #endif
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61 | /* Must match getopt32 option string order */
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62 | enum {
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63 | OPT_C = 1 << 0,
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64 | OPT_V = 1 << 1,
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65 | OPT_H = 1 << 2,
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66 | OPT_h = 1 << 3,
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67 | OPT_F = 1 << 4,
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68 | OPT_i = 1 << 5,
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69 | OPT_n = 1 << 6,
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70 | OPT_p = 1 << 7,
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71 | OPT_q = 1 << 8,
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72 | OPT_R = 1 << 9,
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73 | OPT_r = 1 << 10,
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74 | OPT_s = 1 << 11,
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75 | OPT_T = 1 << 12,
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76 | OPT_t = 1 << 13,
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77 | OPT_S = 1 << 14,
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78 | OPT_A = 1 << 15,
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79 | OPT_O = 1 << 16,
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80 | OPT_o = 1 << 17,
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81 | OPT_x = 1 << 18,
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82 | OPT_f = 1 << 19,
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83 | OPT_B = 1 << 20,
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84 | /* The rest has variable bit positions, need to be clever */
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85 | OPTBIT_B = 20,
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86 | USE_FOR_MMU( OPTBIT_b,)
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87 | IF_FEATURE_UDHCPC_ARPING(OPTBIT_a,)
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88 | IF_FEATURE_UDHCP_PORT( OPTBIT_P,)
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89 | USE_FOR_MMU( OPT_b = 1 << OPTBIT_b,)
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90 | IF_FEATURE_UDHCPC_ARPING(OPT_a = 1 << OPTBIT_a,)
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91 | IF_FEATURE_UDHCP_PORT( OPT_P = 1 << OPTBIT_P,)
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92 | };
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93 |
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94 |
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95 | /*** Script execution code ***/
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96 |
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97 | /* get a rough idea of how long an option will be (rounding up...) */
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98 | static const uint8_t len_of_option_as_string[] = {
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99 | [OPTION_IP ] = sizeof("255.255.255.255 "),
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100 | [OPTION_IP_PAIR ] = sizeof("255.255.255.255 ") * 2,
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101 | [OPTION_STATIC_ROUTES ] = sizeof("255.255.255.255/32 255.255.255.255 "),
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102 | [OPTION_6RD ] = sizeof("32 128 ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff 255.255.255.255 "),
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103 | [OPTION_STRING ] = 1,
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104 | [OPTION_STRING_HOST ] = 1,
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105 | #if ENABLE_FEATURE_UDHCP_RFC3397
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106 | [OPTION_DNS_STRING ] = 1, /* unused */
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107 | /* Hmmm, this severely overestimates size if SIP_SERVERS option
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108 | * is in domain name form: N-byte option in binary form
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109 | * mallocs ~16*N bytes. But it is freed almost at once.
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110 | */
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111 | [OPTION_SIP_SERVERS ] = sizeof("255.255.255.255 "),
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112 | #endif
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113 | // [OPTION_BOOLEAN ] = sizeof("yes "),
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114 | [OPTION_U8 ] = sizeof("255 "),
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115 | [OPTION_U16 ] = sizeof("65535 "),
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116 | // [OPTION_S16 ] = sizeof("-32768 "),
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117 | [OPTION_U32 ] = sizeof("4294967295 "),
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118 | [OPTION_S32 ] = sizeof("-2147483684 "),
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119 | };
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120 |
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121 | /* note: ip is a pointer to an IP in network order, possibly misaliged */
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122 | static int sprint_nip(char *dest, const char *pre, const uint8_t *ip)
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123 | {
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124 | return sprintf(dest, "%s%u.%u.%u.%u", pre, ip[0], ip[1], ip[2], ip[3]);
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125 | }
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126 |
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127 | /* really simple implementation, just count the bits */
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128 | static int mton(uint32_t mask)
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129 | {
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130 | int i = 0;
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131 | mask = ntohl(mask); /* 111110000-like bit pattern */
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132 | while (mask) {
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133 | i++;
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134 | mask <<= 1;
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135 | }
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136 | return i;
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137 | }
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138 |
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139 | /* Check if a given label represents a valid DNS label
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140 | * Return pointer to the first character after the label upon success,
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141 | * NULL otherwise.
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142 | * See RFC1035, 2.3.1
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143 | */
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144 | /* We don't need to be particularly anal. For example, allowing _, hyphen
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145 | * at the end, or leading and trailing dots would be ok, since it
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146 | * can't be used for attacks. (Leading hyphen can be, if someone uses
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147 | * cmd "$hostname"
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148 | * in the script: then hostname may be treated as an option)
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149 | */
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150 | static const char *valid_domain_label(const char *label)
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151 | {
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152 | unsigned char ch;
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153 | unsigned pos = 0;
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154 |
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155 | for (;;) {
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156 | ch = *label;
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157 | if ((ch|0x20) < 'a' || (ch|0x20) > 'z') {
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158 | if (pos == 0) {
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159 | /* label must begin with letter */
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160 | return NULL;
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161 | }
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162 | if (ch < '0' || ch > '9') {
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163 | if (ch == '\0' || ch == '.')
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164 | return label;
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165 | /* DNS allows only '-', but we are more permissive */
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166 | if (ch != '-' && ch != '_')
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167 | return NULL;
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168 | }
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169 | }
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170 | label++;
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171 | pos++;
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172 | //Do we want this?
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173 | //if (pos > 63) /* NS_MAXLABEL; labels must be 63 chars or less */
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174 | // return NULL;
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175 | }
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176 | }
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177 |
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178 | /* Check if a given name represents a valid DNS name */
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179 | /* See RFC1035, 2.3.1 */
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180 | static int good_hostname(const char *name)
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181 | {
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182 | //const char *start = name;
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183 |
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184 | for (;;) {
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185 | name = valid_domain_label(name);
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186 | if (!name)
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187 | return 0;
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188 | if (!name[0])
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189 | return 1;
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190 | //Do we want this?
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191 | //return ((name - start) < 1025); /* NS_MAXDNAME */
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192 | name++;
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193 | }
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194 | }
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195 |
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196 | /* Create "opt_name=opt_value" string */
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197 | static NOINLINE char *xmalloc_optname_optval(uint8_t *option, const struct dhcp_optflag *optflag, const char *opt_name)
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198 | {
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199 | unsigned upper_length;
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200 | int len, type, optlen;
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201 | char *dest, *ret;
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202 |
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203 | /* option points to OPT_DATA, need to go back to get OPT_LEN */
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204 | len = option[-OPT_DATA + OPT_LEN];
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205 |
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206 | type = optflag->flags & OPTION_TYPE_MASK;
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207 | optlen = dhcp_option_lengths[type];
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208 | upper_length = len_of_option_as_string[type]
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209 | * ((unsigned)(len + optlen - 1) / (unsigned)optlen);
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210 |
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211 | dest = ret = xmalloc(upper_length + strlen(opt_name) + 2);
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212 | dest += sprintf(ret, "%s=", opt_name);
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213 |
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214 | while (len >= optlen) {
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215 | switch (type) {
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216 | case OPTION_IP:
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217 | case OPTION_IP_PAIR:
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218 | dest += sprint_nip(dest, "", option);
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219 | if (type == OPTION_IP)
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220 | break;
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221 | dest += sprint_nip(dest, "/", option + 4);
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222 | break;
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223 | // case OPTION_BOOLEAN:
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224 | // dest += sprintf(dest, *option ? "yes" : "no");
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225 | // break;
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226 | case OPTION_U8:
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227 | dest += sprintf(dest, "%u", *option);
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228 | break;
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229 | // case OPTION_S16:
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230 | case OPTION_U16: {
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231 | uint16_t val_u16;
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232 | move_from_unaligned16(val_u16, option);
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233 | dest += sprintf(dest, "%u", ntohs(val_u16));
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234 | break;
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235 | }
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236 | case OPTION_S32:
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237 | case OPTION_U32: {
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238 | uint32_t val_u32;
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239 | move_from_unaligned32(val_u32, option);
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240 | dest += sprintf(dest, type == OPTION_U32 ? "%lu" : "%ld", (unsigned long) ntohl(val_u32));
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241 | break;
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242 | }
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243 | /* Note: options which use 'return' instead of 'break'
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244 | * (for example, OPTION_STRING) skip the code which handles
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245 | * the case of list of options.
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246 | */
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247 | case OPTION_STRING:
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248 | case OPTION_STRING_HOST:
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249 | memcpy(dest, option, len);
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250 | dest[len] = '\0';
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251 | if (type == OPTION_STRING_HOST && !good_hostname(dest))
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252 | safe_strncpy(dest, "bad", len);
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253 | return ret;
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254 | case OPTION_STATIC_ROUTES: {
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255 | /* Option binary format:
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256 | * mask [one byte, 0..32]
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257 | * ip [big endian, 0..4 bytes depending on mask]
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258 | * router [big endian, 4 bytes]
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259 | * may be repeated
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260 | *
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261 | * We convert it to a string "IP/MASK ROUTER IP2/MASK2 ROUTER2"
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262 | */
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263 | const char *pfx = "";
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264 |
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265 | while (len >= 1 + 4) { /* mask + 0-byte ip + router */
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266 | uint32_t nip;
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267 | uint8_t *p;
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268 | unsigned mask;
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269 | int bytes;
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270 |
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271 | mask = *option++;
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272 | if (mask > 32)
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273 | break;
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274 | len--;
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275 |
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276 | nip = 0;
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277 | p = (void*) &nip;
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278 | bytes = (mask + 7) / 8; /* 0 -> 0, 1..8 -> 1, 9..16 -> 2 etc */
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279 | while (--bytes >= 0) {
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280 | *p++ = *option++;
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281 | len--;
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282 | }
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283 | if (len < 4)
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284 | break;
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285 |
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286 | /* print ip/mask */
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287 | dest += sprint_nip(dest, pfx, (void*) &nip);
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288 | pfx = " ";
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289 | dest += sprintf(dest, "/%u ", mask);
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290 | /* print router */
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291 | dest += sprint_nip(dest, "", option);
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292 | option += 4;
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293 | len -= 4;
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294 | }
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295 |
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296 | return ret;
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297 | }
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298 | case OPTION_6RD:
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299 | /* Option binary format (see RFC 5969):
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300 | * 0 1 2 3
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301 | * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
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302 | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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303 | * | OPTION_6RD | option-length | IPv4MaskLen | 6rdPrefixLen |
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304 | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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305 | * | 6rdPrefix |
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306 | * ... (16 octets) ...
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307 | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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308 | * ... 6rdBRIPv4Address(es) ...
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309 | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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310 | * We convert it to a string
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311 | * "IPv4MaskLen 6rdPrefixLen 6rdPrefix 6rdBRIPv4Address..."
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312 | *
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313 | * Sanity check: ensure that our length is at least 22 bytes, that
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314 | * IPv4MaskLen <= 32,
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315 | * 6rdPrefixLen <= 128,
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316 | * 6rdPrefixLen + (32 - IPv4MaskLen) <= 128
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317 | * (2nd condition need no check - it follows from 1st and 3rd).
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318 | * Else, return envvar with empty value ("optname=")
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319 | */
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320 | if (len >= (1 + 1 + 16 + 4)
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321 | && option[0] <= 32
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322 | && (option[1] + 32 - option[0]) <= 128
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323 | ) {
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324 | /* IPv4MaskLen */
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325 | dest += sprintf(dest, "%u ", *option++);
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326 | /* 6rdPrefixLen */
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327 | dest += sprintf(dest, "%u ", *option++);
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328 | /* 6rdPrefix */
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329 | dest += sprint_nip6(dest, /* "", */ option);
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330 | option += 16;
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331 | len -= 1 + 1 + 16 + 4;
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332 | /* "+ 4" above corresponds to the length of IPv4 addr
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333 | * we consume in the loop below */
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334 | while (1) {
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335 | /* 6rdBRIPv4Address(es) */
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336 | dest += sprint_nip(dest, " ", option);
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337 | option += 4;
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338 | len -= 4; /* do we have yet another 4+ bytes? */
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339 | if (len < 0)
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340 | break; /* no */
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341 | }
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342 | }
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343 |
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344 | return ret;
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345 | #if ENABLE_FEATURE_UDHCP_RFC3397
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346 | case OPTION_DNS_STRING:
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347 | /* unpack option into dest; use ret for prefix (i.e., "optname=") */
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348 | dest = dname_dec(option, len, ret);
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349 | if (dest) {
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350 | free(ret);
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351 | return dest;
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352 | }
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353 | /* error. return "optname=" string */
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354 | return ret;
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355 | case OPTION_SIP_SERVERS:
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356 | /* Option binary format:
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357 | * type: byte
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358 | * type=0: domain names, dns-compressed
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359 | * type=1: IP addrs
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360 | */
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361 | option++;
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362 | len--;
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363 | if (option[-1] == 0) {
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364 | dest = dname_dec(option, len, ret);
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365 | if (dest) {
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366 | free(ret);
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367 | return dest;
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368 | }
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369 | } else
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370 | if (option[-1] == 1) {
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371 | const char *pfx = "";
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372 | while (1) {
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373 | len -= 4;
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374 | if (len < 0)
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375 | break;
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376 | dest += sprint_nip(dest, pfx, option);
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377 | pfx = " ";
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378 | option += 4;
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379 | }
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380 | }
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381 | return ret;
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382 | #endif
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383 | } /* switch */
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384 |
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385 | /* If we are here, try to format any remaining data
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386 | * in the option as another, similarly-formatted option
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387 | */
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388 | option += optlen;
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389 | len -= optlen;
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390 | // TODO: it can be a list only if (optflag->flags & OPTION_LIST).
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391 | // Should we bail out/warn if we see multi-ip option which is
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392 | // not allowed to be such (for example, DHCP_BROADCAST)? -
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393 | if (len < optlen /* || !(optflag->flags & OPTION_LIST) */)
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394 | break;
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395 | *dest++ = ' ';
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396 | *dest = '\0';
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397 | } /* while */
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398 |
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399 | return ret;
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400 | }
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401 |
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402 | /* put all the parameters into the environment */
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403 | static char **fill_envp(struct dhcp_packet *packet)
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404 | {
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405 | int envc;
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406 | int i;
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407 | char **envp, **curr;
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408 | const char *opt_name;
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409 | uint8_t *temp;
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410 | uint8_t overload = 0;
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411 |
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412 | #define BITMAP unsigned
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413 | #define BBITS (sizeof(BITMAP) * 8)
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414 | #define BMASK(i) (1 << (i & (sizeof(BITMAP) * 8 - 1)))
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415 | #define FOUND_OPTS(i) (found_opts[(unsigned)i / BBITS])
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416 | BITMAP found_opts[256 / BBITS];
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417 |
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418 | memset(found_opts, 0, sizeof(found_opts));
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419 |
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420 | /* We need 6 elements for:
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421 | * "interface=IFACE"
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422 | * "ip=N.N.N.N" from packet->yiaddr
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423 | * "siaddr=IP" from packet->siaddr_nip (unless 0)
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424 | * "boot_file=FILE" from packet->file (unless overloaded)
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425 | * "sname=SERVER_HOSTNAME" from packet->sname (unless overloaded)
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426 | * terminating NULL
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427 | */
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428 | envc = 6;
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429 | /* +1 element for each option, +2 for subnet option: */
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430 | if (packet) {
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431 | /* note: do not search for "pad" (0) and "end" (255) options */
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432 | //TODO: change logic to scan packet _once_
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433 | for (i = 1; i < 255; i++) {
|
---|
434 | temp = udhcp_get_option(packet, i);
|
---|
435 | if (temp) {
|
---|
436 | if (i == DHCP_OPTION_OVERLOAD)
|
---|
437 | overload = *temp;
|
---|
438 | else if (i == DHCP_SUBNET)
|
---|
439 | envc++; /* for $mask */
|
---|
440 | envc++;
|
---|
441 | /*if (i != DHCP_MESSAGE_TYPE)*/
|
---|
442 | FOUND_OPTS(i) |= BMASK(i);
|
---|
443 | }
|
---|
444 | }
|
---|
445 | }
|
---|
446 | curr = envp = xzalloc(sizeof(envp[0]) * envc);
|
---|
447 |
|
---|
448 | *curr = xasprintf("interface=%s", client_config.interface);
|
---|
449 | putenv(*curr++);
|
---|
450 |
|
---|
451 | if (!packet)
|
---|
452 | return envp;
|
---|
453 |
|
---|
454 | /* Export BOOTP fields. Fields we don't (yet?) export:
|
---|
455 | * uint8_t op; // always BOOTREPLY
|
---|
456 | * uint8_t htype; // hardware address type. 1 = 10mb ethernet
|
---|
457 | * uint8_t hlen; // hardware address length
|
---|
458 | * uint8_t hops; // used by relay agents only
|
---|
459 | * uint32_t xid;
|
---|
460 | * uint16_t secs; // elapsed since client began acquisition/renewal
|
---|
461 | * uint16_t flags; // only one flag so far: bcast. Never set by server
|
---|
462 | * uint32_t ciaddr; // client IP (usually == yiaddr. can it be different
|
---|
463 | * // if during renew server wants to give us differn IP?)
|
---|
464 | * uint32_t gateway_nip; // relay agent IP address
|
---|
465 | * uint8_t chaddr[16]; // link-layer client hardware address (MAC)
|
---|
466 | * TODO: export gateway_nip as $giaddr?
|
---|
467 | */
|
---|
468 | /* Most important one: yiaddr as $ip */
|
---|
469 | *curr = xmalloc(sizeof("ip=255.255.255.255"));
|
---|
470 | sprint_nip(*curr, "ip=", (uint8_t *) &packet->yiaddr);
|
---|
471 | putenv(*curr++);
|
---|
472 | if (packet->siaddr_nip) {
|
---|
473 | /* IP address of next server to use in bootstrap */
|
---|
474 | *curr = xmalloc(sizeof("siaddr=255.255.255.255"));
|
---|
475 | sprint_nip(*curr, "siaddr=", (uint8_t *) &packet->siaddr_nip);
|
---|
476 | putenv(*curr++);
|
---|
477 | }
|
---|
478 | if (!(overload & FILE_FIELD) && packet->file[0]) {
|
---|
479 | /* watch out for invalid packets */
|
---|
480 | *curr = xasprintf("boot_file=%."DHCP_PKT_FILE_LEN_STR"s", packet->file);
|
---|
481 | putenv(*curr++);
|
---|
482 | }
|
---|
483 | if (!(overload & SNAME_FIELD) && packet->sname[0]) {
|
---|
484 | /* watch out for invalid packets */
|
---|
485 | *curr = xasprintf("sname=%."DHCP_PKT_SNAME_LEN_STR"s", packet->sname);
|
---|
486 | putenv(*curr++);
|
---|
487 | }
|
---|
488 |
|
---|
489 | /* Export known DHCP options */
|
---|
490 | opt_name = dhcp_option_strings;
|
---|
491 | i = 0;
|
---|
492 | while (*opt_name) {
|
---|
493 | uint8_t code = dhcp_optflags[i].code;
|
---|
494 | BITMAP *found_ptr = &FOUND_OPTS(code);
|
---|
495 | BITMAP found_mask = BMASK(code);
|
---|
496 | if (!(*found_ptr & found_mask))
|
---|
497 | goto next;
|
---|
498 | *found_ptr &= ~found_mask; /* leave only unknown options */
|
---|
499 | temp = udhcp_get_option(packet, code);
|
---|
500 | *curr = xmalloc_optname_optval(temp, &dhcp_optflags[i], opt_name);
|
---|
501 | putenv(*curr++);
|
---|
502 | if (code == DHCP_SUBNET) {
|
---|
503 | /* Subnet option: make things like "$ip/$mask" possible */
|
---|
504 | uint32_t subnet;
|
---|
505 | move_from_unaligned32(subnet, temp);
|
---|
506 | *curr = xasprintf("mask=%u", mton(subnet));
|
---|
507 | putenv(*curr++);
|
---|
508 | }
|
---|
509 | next:
|
---|
510 | opt_name += strlen(opt_name) + 1;
|
---|
511 | i++;
|
---|
512 | }
|
---|
513 | /* Export unknown options */
|
---|
514 | for (i = 0; i < 256;) {
|
---|
515 | BITMAP bitmap = FOUND_OPTS(i);
|
---|
516 | if (!bitmap) {
|
---|
517 | i += BBITS;
|
---|
518 | continue;
|
---|
519 | }
|
---|
520 | if (bitmap & BMASK(i)) {
|
---|
521 | unsigned len, ofs;
|
---|
522 |
|
---|
523 | temp = udhcp_get_option(packet, i);
|
---|
524 | /* udhcp_get_option returns ptr to data portion,
|
---|
525 | * need to go back to get len
|
---|
526 | */
|
---|
527 | len = temp[-OPT_DATA + OPT_LEN];
|
---|
528 | *curr = xmalloc(sizeof("optNNN=") + 1 + len*2);
|
---|
529 | ofs = sprintf(*curr, "opt%u=", i);
|
---|
530 | *bin2hex(*curr + ofs, (void*) temp, len) = '\0';
|
---|
531 | putenv(*curr++);
|
---|
532 | }
|
---|
533 | i++;
|
---|
534 | }
|
---|
535 |
|
---|
536 | return envp;
|
---|
537 | }
|
---|
538 |
|
---|
539 | /* Call a script with a par file and env vars */
|
---|
540 | static void udhcp_run_script(struct dhcp_packet *packet, const char *name)
|
---|
541 | {
|
---|
542 | char **envp, **curr;
|
---|
543 | char *argv[3];
|
---|
544 |
|
---|
545 | envp = fill_envp(packet);
|
---|
546 |
|
---|
547 | /* call script */
|
---|
548 | log1("Executing %s %s", client_config.script, name);
|
---|
549 | argv[0] = (char*) client_config.script;
|
---|
550 | argv[1] = (char*) name;
|
---|
551 | argv[2] = NULL;
|
---|
552 | spawn_and_wait(argv);
|
---|
553 |
|
---|
554 | for (curr = envp; *curr; curr++) {
|
---|
555 | log2(" %s", *curr);
|
---|
556 | bb_unsetenv_and_free(*curr);
|
---|
557 | }
|
---|
558 | free(envp);
|
---|
559 | }
|
---|
560 |
|
---|
561 |
|
---|
562 | /*** Sending/receiving packets ***/
|
---|
563 |
|
---|
564 | static ALWAYS_INLINE uint32_t random_xid(void)
|
---|
565 | {
|
---|
566 | return rand();
|
---|
567 | }
|
---|
568 |
|
---|
569 | /* Initialize the packet with the proper defaults */
|
---|
570 | static void init_packet(struct dhcp_packet *packet, char type)
|
---|
571 | {
|
---|
572 | uint16_t secs;
|
---|
573 |
|
---|
574 | /* Fill in: op, htype, hlen, cookie fields; message type option: */
|
---|
575 | udhcp_init_header(packet, type);
|
---|
576 |
|
---|
577 | packet->xid = random_xid();
|
---|
578 |
|
---|
579 | client_config.last_secs = monotonic_sec();
|
---|
580 | if (client_config.first_secs == 0)
|
---|
581 | client_config.first_secs = client_config.last_secs;
|
---|
582 | secs = client_config.last_secs - client_config.first_secs;
|
---|
583 | packet->secs = htons(secs);
|
---|
584 |
|
---|
585 | memcpy(packet->chaddr, client_config.client_mac, 6);
|
---|
586 | if (client_config.clientid)
|
---|
587 | udhcp_add_binary_option(packet, client_config.clientid);
|
---|
588 | }
|
---|
589 |
|
---|
590 | static void add_client_options(struct dhcp_packet *packet)
|
---|
591 | {
|
---|
592 | int i, end, len;
|
---|
593 |
|
---|
594 | udhcp_add_simple_option(packet, DHCP_MAX_SIZE, htons(IP_UDP_DHCP_SIZE));
|
---|
595 |
|
---|
596 | /* Add a "param req" option with the list of options we'd like to have
|
---|
597 | * from stubborn DHCP servers. Pull the data from the struct in common.c.
|
---|
598 | * No bounds checking because it goes towards the head of the packet. */
|
---|
599 | end = udhcp_end_option(packet->options);
|
---|
600 | len = 0;
|
---|
601 | for (i = 1; i < DHCP_END; i++) {
|
---|
602 | if (client_config.opt_mask[i >> 3] & (1 << (i & 7))) {
|
---|
603 | packet->options[end + OPT_DATA + len] = i;
|
---|
604 | len++;
|
---|
605 | }
|
---|
606 | }
|
---|
607 | if (len) {
|
---|
608 | packet->options[end + OPT_CODE] = DHCP_PARAM_REQ;
|
---|
609 | packet->options[end + OPT_LEN] = len;
|
---|
610 | packet->options[end + OPT_DATA + len] = DHCP_END;
|
---|
611 | }
|
---|
612 |
|
---|
613 | if (client_config.vendorclass)
|
---|
614 | udhcp_add_binary_option(packet, client_config.vendorclass);
|
---|
615 | if (client_config.hostname)
|
---|
616 | udhcp_add_binary_option(packet, client_config.hostname);
|
---|
617 | if (client_config.fqdn)
|
---|
618 | udhcp_add_binary_option(packet, client_config.fqdn);
|
---|
619 |
|
---|
620 | /* Request broadcast replies if we have no IP addr */
|
---|
621 | if ((option_mask32 & OPT_B) && packet->ciaddr == 0)
|
---|
622 | packet->flags |= htons(BROADCAST_FLAG);
|
---|
623 |
|
---|
624 | /* Add -x options if any */
|
---|
625 | {
|
---|
626 | struct option_set *curr = client_config.options;
|
---|
627 | while (curr) {
|
---|
628 | udhcp_add_binary_option(packet, curr->data);
|
---|
629 | curr = curr->next;
|
---|
630 | }
|
---|
631 | // if (client_config.sname)
|
---|
632 | // strncpy((char*)packet->sname, client_config.sname, sizeof(packet->sname) - 1);
|
---|
633 | // if (client_config.boot_file)
|
---|
634 | // strncpy((char*)packet->file, client_config.boot_file, sizeof(packet->file) - 1);
|
---|
635 | }
|
---|
636 |
|
---|
637 | // This will be needed if we remove -V VENDOR_STR in favor of
|
---|
638 | // -x vendor:VENDOR_STR
|
---|
639 | //if (!udhcp_find_option(packet.options, DHCP_VENDOR))
|
---|
640 | // /* not set, set the default vendor ID */
|
---|
641 | // ...add (DHCP_VENDOR, "udhcp "BB_VER) opt...
|
---|
642 | }
|
---|
643 |
|
---|
644 | /* RFC 2131
|
---|
645 | * 4.4.4 Use of broadcast and unicast
|
---|
646 | *
|
---|
647 | * The DHCP client broadcasts DHCPDISCOVER, DHCPREQUEST and DHCPINFORM
|
---|
648 | * messages, unless the client knows the address of a DHCP server.
|
---|
649 | * The client unicasts DHCPRELEASE messages to the server. Because
|
---|
650 | * the client is declining the use of the IP address supplied by the server,
|
---|
651 | * the client broadcasts DHCPDECLINE messages.
|
---|
652 | *
|
---|
653 | * When the DHCP client knows the address of a DHCP server, in either
|
---|
654 | * INIT or REBOOTING state, the client may use that address
|
---|
655 | * in the DHCPDISCOVER or DHCPREQUEST rather than the IP broadcast address.
|
---|
656 | * The client may also use unicast to send DHCPINFORM messages
|
---|
657 | * to a known DHCP server. If the client receives no response to DHCP
|
---|
658 | * messages sent to the IP address of a known DHCP server, the DHCP
|
---|
659 | * client reverts to using the IP broadcast address.
|
---|
660 | */
|
---|
661 |
|
---|
662 | static int raw_bcast_from_client_config_ifindex(struct dhcp_packet *packet)
|
---|
663 | {
|
---|
664 | return udhcp_send_raw_packet(packet,
|
---|
665 | /*src*/ INADDR_ANY, CLIENT_PORT,
|
---|
666 | /*dst*/ INADDR_BROADCAST, SERVER_PORT, MAC_BCAST_ADDR,
|
---|
667 | client_config.ifindex);
|
---|
668 | }
|
---|
669 |
|
---|
670 | /* Broadcast a DHCP discover packet to the network, with an optionally requested IP */
|
---|
671 | /* NOINLINE: limit stack usage in caller */
|
---|
672 | static NOINLINE int send_discover(uint32_t xid, uint32_t requested)
|
---|
673 | {
|
---|
674 | struct dhcp_packet packet;
|
---|
675 |
|
---|
676 | /* Fill in: op, htype, hlen, cookie, chaddr fields,
|
---|
677 | * random xid field (we override it below),
|
---|
678 | * client-id option (unless -C), message type option:
|
---|
679 | */
|
---|
680 | init_packet(&packet, DHCPDISCOVER);
|
---|
681 |
|
---|
682 | packet.xid = xid;
|
---|
683 | if (requested)
|
---|
684 | udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
|
---|
685 |
|
---|
686 | /* Add options: maxsize,
|
---|
687 | * optionally: hostname, fqdn, vendorclass,
|
---|
688 | * "param req" option according to -O, options specified with -x
|
---|
689 | */
|
---|
690 | add_client_options(&packet);
|
---|
691 |
|
---|
692 | bb_info_msg("Sending discover...");
|
---|
693 | return raw_bcast_from_client_config_ifindex(&packet);
|
---|
694 | }
|
---|
695 |
|
---|
696 | /* Broadcast a DHCP request message */
|
---|
697 | /* RFC 2131 3.1 paragraph 3:
|
---|
698 | * "The client _broadcasts_ a DHCPREQUEST message..."
|
---|
699 | */
|
---|
700 | /* NOINLINE: limit stack usage in caller */
|
---|
701 | static NOINLINE int send_select(uint32_t xid, uint32_t server, uint32_t requested)
|
---|
702 | {
|
---|
703 | struct dhcp_packet packet;
|
---|
704 | struct in_addr addr;
|
---|
705 |
|
---|
706 | /*
|
---|
707 | * RFC 2131 4.3.2 DHCPREQUEST message
|
---|
708 | * ...
|
---|
709 | * If the DHCPREQUEST message contains a 'server identifier'
|
---|
710 | * option, the message is in response to a DHCPOFFER message.
|
---|
711 | * Otherwise, the message is a request to verify or extend an
|
---|
712 | * existing lease. If the client uses a 'client identifier'
|
---|
713 | * in a DHCPREQUEST message, it MUST use that same 'client identifier'
|
---|
714 | * in all subsequent messages. If the client included a list
|
---|
715 | * of requested parameters in a DHCPDISCOVER message, it MUST
|
---|
716 | * include that list in all subsequent messages.
|
---|
717 | */
|
---|
718 | /* Fill in: op, htype, hlen, cookie, chaddr fields,
|
---|
719 | * random xid field (we override it below),
|
---|
720 | * client-id option (unless -C), message type option:
|
---|
721 | */
|
---|
722 | init_packet(&packet, DHCPREQUEST);
|
---|
723 |
|
---|
724 | packet.xid = xid;
|
---|
725 | udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
|
---|
726 |
|
---|
727 | udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
|
---|
728 |
|
---|
729 | /* Add options: maxsize,
|
---|
730 | * optionally: hostname, fqdn, vendorclass,
|
---|
731 | * "param req" option according to -O, and options specified with -x
|
---|
732 | */
|
---|
733 | add_client_options(&packet);
|
---|
734 |
|
---|
735 | addr.s_addr = requested;
|
---|
736 | bb_info_msg("Sending select for %s...", inet_ntoa(addr));
|
---|
737 | return raw_bcast_from_client_config_ifindex(&packet);
|
---|
738 | }
|
---|
739 |
|
---|
740 | /* Unicast or broadcast a DHCP renew message */
|
---|
741 | /* NOINLINE: limit stack usage in caller */
|
---|
742 | static NOINLINE int send_renew(uint32_t xid, uint32_t server, uint32_t ciaddr)
|
---|
743 | {
|
---|
744 | struct dhcp_packet packet;
|
---|
745 |
|
---|
746 | /*
|
---|
747 | * RFC 2131 4.3.2 DHCPREQUEST message
|
---|
748 | * ...
|
---|
749 | * DHCPREQUEST generated during RENEWING state:
|
---|
750 | *
|
---|
751 | * 'server identifier' MUST NOT be filled in, 'requested IP address'
|
---|
752 | * option MUST NOT be filled in, 'ciaddr' MUST be filled in with
|
---|
753 | * client's IP address. In this situation, the client is completely
|
---|
754 | * configured, and is trying to extend its lease. This message will
|
---|
755 | * be unicast, so no relay agents will be involved in its
|
---|
756 | * transmission. Because 'giaddr' is therefore not filled in, the
|
---|
757 | * DHCP server will trust the value in 'ciaddr', and use it when
|
---|
758 | * replying to the client.
|
---|
759 | */
|
---|
760 | /* Fill in: op, htype, hlen, cookie, chaddr fields,
|
---|
761 | * random xid field (we override it below),
|
---|
762 | * client-id option (unless -C), message type option:
|
---|
763 | */
|
---|
764 | init_packet(&packet, DHCPREQUEST);
|
---|
765 |
|
---|
766 | packet.xid = xid;
|
---|
767 | packet.ciaddr = ciaddr;
|
---|
768 |
|
---|
769 | /* Add options: maxsize,
|
---|
770 | * optionally: hostname, fqdn, vendorclass,
|
---|
771 | * "param req" option according to -O, and options specified with -x
|
---|
772 | */
|
---|
773 | add_client_options(&packet);
|
---|
774 |
|
---|
775 | bb_info_msg("Sending renew...");
|
---|
776 | if (server)
|
---|
777 | return udhcp_send_kernel_packet(&packet,
|
---|
778 | ciaddr, CLIENT_PORT,
|
---|
779 | server, SERVER_PORT);
|
---|
780 | return raw_bcast_from_client_config_ifindex(&packet);
|
---|
781 | }
|
---|
782 |
|
---|
783 | #if ENABLE_FEATURE_UDHCPC_ARPING
|
---|
784 | /* Broadcast a DHCP decline message */
|
---|
785 | /* NOINLINE: limit stack usage in caller */
|
---|
786 | static NOINLINE int send_decline(/*uint32_t xid,*/ uint32_t server, uint32_t requested)
|
---|
787 | {
|
---|
788 | struct dhcp_packet packet;
|
---|
789 |
|
---|
790 | /* Fill in: op, htype, hlen, cookie, chaddr, random xid fields,
|
---|
791 | * client-id option (unless -C), message type option:
|
---|
792 | */
|
---|
793 | init_packet(&packet, DHCPDECLINE);
|
---|
794 |
|
---|
795 | #if 0
|
---|
796 | /* RFC 2131 says DHCPDECLINE's xid is randomly selected by client,
|
---|
797 | * but in case the server is buggy and wants DHCPDECLINE's xid
|
---|
798 | * to match the xid which started entire handshake,
|
---|
799 | * we use the same xid we used in initial DHCPDISCOVER:
|
---|
800 | */
|
---|
801 | packet.xid = xid;
|
---|
802 | #endif
|
---|
803 | /* DHCPDECLINE uses "requested ip", not ciaddr, to store offered IP */
|
---|
804 | udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
|
---|
805 |
|
---|
806 | udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
|
---|
807 |
|
---|
808 | bb_info_msg("Sending decline...");
|
---|
809 | return raw_bcast_from_client_config_ifindex(&packet);
|
---|
810 | }
|
---|
811 | #endif
|
---|
812 |
|
---|
813 | /* Unicast a DHCP release message */
|
---|
814 | static int send_release(uint32_t server, uint32_t ciaddr)
|
---|
815 | {
|
---|
816 | struct dhcp_packet packet;
|
---|
817 |
|
---|
818 | /* Fill in: op, htype, hlen, cookie, chaddr, random xid fields,
|
---|
819 | * client-id option (unless -C), message type option:
|
---|
820 | */
|
---|
821 | init_packet(&packet, DHCPRELEASE);
|
---|
822 |
|
---|
823 | /* DHCPRELEASE uses ciaddr, not "requested ip", to store IP being released */
|
---|
824 | packet.ciaddr = ciaddr;
|
---|
825 |
|
---|
826 | udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
|
---|
827 |
|
---|
828 | bb_info_msg("Sending release...");
|
---|
829 | return udhcp_send_kernel_packet(&packet, ciaddr, CLIENT_PORT, server, SERVER_PORT);
|
---|
830 | }
|
---|
831 |
|
---|
832 | /* Returns -1 on errors that are fatal for the socket, -2 for those that aren't */
|
---|
833 | /* NOINLINE: limit stack usage in caller */
|
---|
834 | static NOINLINE int udhcp_recv_raw_packet(struct dhcp_packet *dhcp_pkt, int fd)
|
---|
835 | {
|
---|
836 | int bytes;
|
---|
837 | struct ip_udp_dhcp_packet packet;
|
---|
838 | uint16_t check;
|
---|
839 | unsigned char cmsgbuf[CMSG_LEN(sizeof(struct tpacket_auxdata))];
|
---|
840 | struct iovec iov;
|
---|
841 | struct msghdr msg;
|
---|
842 | struct cmsghdr *cmsg;
|
---|
843 |
|
---|
844 | /* used to use just safe_read(fd, &packet, sizeof(packet))
|
---|
845 | * but we need to check for TP_STATUS_CSUMNOTREADY :(
|
---|
846 | */
|
---|
847 | iov.iov_base = &packet;
|
---|
848 | iov.iov_len = sizeof(packet);
|
---|
849 | memset(&msg, 0, sizeof(msg));
|
---|
850 | msg.msg_iov = &iov;
|
---|
851 | msg.msg_iovlen = 1;
|
---|
852 | msg.msg_control = cmsgbuf;
|
---|
853 | msg.msg_controllen = sizeof(cmsgbuf);
|
---|
854 | for (;;) {
|
---|
855 | bytes = recvmsg(fd, &msg, 0);
|
---|
856 | if (bytes < 0) {
|
---|
857 | if (errno == EINTR)
|
---|
858 | continue;
|
---|
859 | log1("Packet read error, ignoring");
|
---|
860 | /* NB: possible down interface, etc. Caller should pause. */
|
---|
861 | return bytes; /* returns -1 */
|
---|
862 | }
|
---|
863 | break;
|
---|
864 | }
|
---|
865 |
|
---|
866 | if (bytes < (int) (sizeof(packet.ip) + sizeof(packet.udp))) {
|
---|
867 | log1("Packet is too short, ignoring");
|
---|
868 | return -2;
|
---|
869 | }
|
---|
870 |
|
---|
871 | if (bytes < ntohs(packet.ip.tot_len)) {
|
---|
872 | /* packet is bigger than sizeof(packet), we did partial read */
|
---|
873 | log1("Oversized packet, ignoring");
|
---|
874 | return -2;
|
---|
875 | }
|
---|
876 |
|
---|
877 | /* ignore any extra garbage bytes */
|
---|
878 | bytes = ntohs(packet.ip.tot_len);
|
---|
879 |
|
---|
880 | /* make sure its the right packet for us, and that it passes sanity checks */
|
---|
881 | if (packet.ip.protocol != IPPROTO_UDP
|
---|
882 | || packet.ip.version != IPVERSION
|
---|
883 | || packet.ip.ihl != (sizeof(packet.ip) >> 2)
|
---|
884 | || packet.udp.dest != htons(CLIENT_PORT)
|
---|
885 | /* || bytes > (int) sizeof(packet) - can't happen */
|
---|
886 | || ntohs(packet.udp.len) != (uint16_t)(bytes - sizeof(packet.ip))
|
---|
887 | ) {
|
---|
888 | log1("Unrelated/bogus packet, ignoring");
|
---|
889 | return -2;
|
---|
890 | }
|
---|
891 |
|
---|
892 | /* verify IP checksum */
|
---|
893 | check = packet.ip.check;
|
---|
894 | packet.ip.check = 0;
|
---|
895 | if (check != inet_cksum((uint16_t *)&packet.ip, sizeof(packet.ip))) {
|
---|
896 | log1("Bad IP header checksum, ignoring");
|
---|
897 | return -2;
|
---|
898 | }
|
---|
899 |
|
---|
900 | for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
|
---|
901 | if (cmsg->cmsg_level == SOL_PACKET
|
---|
902 | && cmsg->cmsg_type == PACKET_AUXDATA
|
---|
903 | ) {
|
---|
904 | /* some VMs don't checksum UDP and TCP data
|
---|
905 | * they send to the same physical machine,
|
---|
906 | * here we detect this case:
|
---|
907 | */
|
---|
908 | struct tpacket_auxdata *aux = (void *)CMSG_DATA(cmsg);
|
---|
909 | if (aux->tp_status & TP_STATUS_CSUMNOTREADY)
|
---|
910 | goto skip_udp_sum_check;
|
---|
911 | }
|
---|
912 | }
|
---|
913 |
|
---|
914 | /* verify UDP checksum. IP header has to be modified for this */
|
---|
915 | memset(&packet.ip, 0, offsetof(struct iphdr, protocol));
|
---|
916 | /* ip.xx fields which are not memset: protocol, check, saddr, daddr */
|
---|
917 | packet.ip.tot_len = packet.udp.len; /* yes, this is needed */
|
---|
918 | check = packet.udp.check;
|
---|
919 | packet.udp.check = 0;
|
---|
920 | if (check && check != inet_cksum((uint16_t *)&packet, bytes)) {
|
---|
921 | log1("Packet with bad UDP checksum received, ignoring");
|
---|
922 | return -2;
|
---|
923 | }
|
---|
924 | skip_udp_sum_check:
|
---|
925 |
|
---|
926 | if (packet.data.cookie != htonl(DHCP_MAGIC)) {
|
---|
927 | bb_info_msg("Packet with bad magic, ignoring");
|
---|
928 | return -2;
|
---|
929 | }
|
---|
930 |
|
---|
931 | log1("Received a packet");
|
---|
932 | udhcp_dump_packet(&packet.data);
|
---|
933 |
|
---|
934 | bytes -= sizeof(packet.ip) + sizeof(packet.udp);
|
---|
935 | memcpy(dhcp_pkt, &packet.data, bytes);
|
---|
936 | return bytes;
|
---|
937 | }
|
---|
938 |
|
---|
939 |
|
---|
940 | /*** Main ***/
|
---|
941 |
|
---|
942 | static int sockfd = -1;
|
---|
943 |
|
---|
944 | #define LISTEN_NONE 0
|
---|
945 | #define LISTEN_KERNEL 1
|
---|
946 | #define LISTEN_RAW 2
|
---|
947 | static smallint listen_mode;
|
---|
948 |
|
---|
949 | /* initial state: (re)start DHCP negotiation */
|
---|
950 | #define INIT_SELECTING 0
|
---|
951 | /* discover was sent, DHCPOFFER reply received */
|
---|
952 | #define REQUESTING 1
|
---|
953 | /* select/renew was sent, DHCPACK reply received */
|
---|
954 | #define BOUND 2
|
---|
955 | /* half of lease passed, want to renew it by sending unicast renew requests */
|
---|
956 | #define RENEWING 3
|
---|
957 | /* renew requests were not answered, lease is almost over, send broadcast renew */
|
---|
958 | #define REBINDING 4
|
---|
959 | /* manually requested renew (SIGUSR1) */
|
---|
960 | #define RENEW_REQUESTED 5
|
---|
961 | /* release, possibly manually requested (SIGUSR2) */
|
---|
962 | #define RELEASED 6
|
---|
963 | static smallint state;
|
---|
964 |
|
---|
965 | static int udhcp_raw_socket(int ifindex)
|
---|
966 | {
|
---|
967 | int fd;
|
---|
968 | struct sockaddr_ll sock;
|
---|
969 |
|
---|
970 | /*
|
---|
971 | * Comment:
|
---|
972 | *
|
---|
973 | * I've selected not to see LL header, so BPF doesn't see it, too.
|
---|
974 | * The filter may also pass non-IP and non-ARP packets, but we do
|
---|
975 | * a more complete check when receiving the message in userspace.
|
---|
976 | *
|
---|
977 | * and filter shamelessly stolen from:
|
---|
978 | *
|
---|
979 | * http://www.flamewarmaster.de/software/dhcpclient/
|
---|
980 | *
|
---|
981 | * There are a few other interesting ideas on that page (look under
|
---|
982 | * "Motivation"). Use of netlink events is most interesting. Think
|
---|
983 | * of various network servers listening for events and reconfiguring.
|
---|
984 | * That would obsolete sending HUP signals and/or make use of restarts.
|
---|
985 | *
|
---|
986 | * Copyright: 2006, 2007 Stefan Rompf <sux@loplof.de>.
|
---|
987 | * License: GPL v2.
|
---|
988 | *
|
---|
989 | * TODO: make conditional?
|
---|
990 | */
|
---|
991 | static const struct sock_filter filter_instr[] = {
|
---|
992 | /* load 9th byte (protocol) */
|
---|
993 | BPF_STMT(BPF_LD|BPF_B|BPF_ABS, 9),
|
---|
994 | /* jump to L1 if it is IPPROTO_UDP, else to L4 */
|
---|
995 | BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, IPPROTO_UDP, 0, 6),
|
---|
996 | /* L1: load halfword from offset 6 (flags and frag offset) */
|
---|
997 | BPF_STMT(BPF_LD|BPF_H|BPF_ABS, 6),
|
---|
998 | /* jump to L4 if any bits in frag offset field are set, else to L2 */
|
---|
999 | BPF_JUMP(BPF_JMP|BPF_JSET|BPF_K, 0x1fff, 4, 0),
|
---|
1000 | /* L2: skip IP header (load index reg with header len) */
|
---|
1001 | BPF_STMT(BPF_LDX|BPF_B|BPF_MSH, 0),
|
---|
1002 | /* load udp destination port from halfword[header_len + 2] */
|
---|
1003 | BPF_STMT(BPF_LD|BPF_H|BPF_IND, 2),
|
---|
1004 | /* jump to L3 if udp dport is CLIENT_PORT, else to L4 */
|
---|
1005 | BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, 68, 0, 1),
|
---|
1006 | /* L3: accept packet */
|
---|
1007 | BPF_STMT(BPF_RET|BPF_K, 0xffffffff),
|
---|
1008 | /* L4: discard packet */
|
---|
1009 | BPF_STMT(BPF_RET|BPF_K, 0),
|
---|
1010 | };
|
---|
1011 | static const struct sock_fprog filter_prog = {
|
---|
1012 | .len = sizeof(filter_instr) / sizeof(filter_instr[0]),
|
---|
1013 | /* casting const away: */
|
---|
1014 | .filter = (struct sock_filter *) filter_instr,
|
---|
1015 | };
|
---|
1016 |
|
---|
1017 | log1("Opening raw socket on ifindex %d", ifindex); //log2?
|
---|
1018 |
|
---|
1019 | fd = xsocket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP));
|
---|
1020 | log1("Got raw socket fd"); //log2?
|
---|
1021 |
|
---|
1022 | sock.sll_family = AF_PACKET;
|
---|
1023 | sock.sll_protocol = htons(ETH_P_IP);
|
---|
1024 | sock.sll_ifindex = ifindex;
|
---|
1025 | xbind(fd, (struct sockaddr *) &sock, sizeof(sock));
|
---|
1026 |
|
---|
1027 | if (CLIENT_PORT == 68) {
|
---|
1028 | /* Use only if standard port is in use */
|
---|
1029 | /* Ignoring error (kernel may lack support for this) */
|
---|
1030 | if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &filter_prog,
|
---|
1031 | sizeof(filter_prog)) >= 0)
|
---|
1032 | log1("Attached filter to raw socket fd"); // log?
|
---|
1033 | }
|
---|
1034 |
|
---|
1035 | if (setsockopt(fd, SOL_PACKET, PACKET_AUXDATA,
|
---|
1036 | &const_int_1, sizeof(int)) < 0
|
---|
1037 | ) {
|
---|
1038 | if (errno != ENOPROTOOPT)
|
---|
1039 | log1("Can't set PACKET_AUXDATA on raw socket");
|
---|
1040 | }
|
---|
1041 |
|
---|
1042 | log1("Created raw socket");
|
---|
1043 |
|
---|
1044 | return fd;
|
---|
1045 | }
|
---|
1046 |
|
---|
1047 | static void change_listen_mode(int new_mode)
|
---|
1048 | {
|
---|
1049 | log1("Entering listen mode: %s",
|
---|
1050 | new_mode != LISTEN_NONE
|
---|
1051 | ? (new_mode == LISTEN_KERNEL ? "kernel" : "raw")
|
---|
1052 | : "none"
|
---|
1053 | );
|
---|
1054 |
|
---|
1055 | listen_mode = new_mode;
|
---|
1056 | if (sockfd >= 0) {
|
---|
1057 | close(sockfd);
|
---|
1058 | sockfd = -1;
|
---|
1059 | }
|
---|
1060 | if (new_mode == LISTEN_KERNEL)
|
---|
1061 | sockfd = udhcp_listen_socket(/*INADDR_ANY,*/ CLIENT_PORT, client_config.interface);
|
---|
1062 | else if (new_mode != LISTEN_NONE)
|
---|
1063 | sockfd = udhcp_raw_socket(client_config.ifindex);
|
---|
1064 | /* else LISTEN_NONE: sockfd stays closed */
|
---|
1065 | }
|
---|
1066 |
|
---|
1067 | /* Called only on SIGUSR1 */
|
---|
1068 | static void perform_renew(void)
|
---|
1069 | {
|
---|
1070 | bb_info_msg("Performing a DHCP renew");
|
---|
1071 | switch (state) {
|
---|
1072 | case BOUND:
|
---|
1073 | change_listen_mode(LISTEN_KERNEL);
|
---|
1074 | case RENEWING:
|
---|
1075 | case REBINDING:
|
---|
1076 | state = RENEW_REQUESTED;
|
---|
1077 | break;
|
---|
1078 | case RENEW_REQUESTED: /* impatient are we? fine, square 1 */
|
---|
1079 | udhcp_run_script(NULL, "deconfig");
|
---|
1080 | case REQUESTING:
|
---|
1081 | case RELEASED:
|
---|
1082 | change_listen_mode(LISTEN_RAW);
|
---|
1083 | state = INIT_SELECTING;
|
---|
1084 | break;
|
---|
1085 | case INIT_SELECTING:
|
---|
1086 | break;
|
---|
1087 | }
|
---|
1088 | }
|
---|
1089 |
|
---|
1090 | static void perform_release(uint32_t server_addr, uint32_t requested_ip)
|
---|
1091 | {
|
---|
1092 | char buffer[sizeof("255.255.255.255")];
|
---|
1093 | struct in_addr temp_addr;
|
---|
1094 |
|
---|
1095 | /* send release packet */
|
---|
1096 | if (state == BOUND || state == RENEWING || state == REBINDING) {
|
---|
1097 | temp_addr.s_addr = server_addr;
|
---|
1098 | strcpy(buffer, inet_ntoa(temp_addr));
|
---|
1099 | temp_addr.s_addr = requested_ip;
|
---|
1100 | bb_info_msg("Unicasting a release of %s to %s",
|
---|
1101 | inet_ntoa(temp_addr), buffer);
|
---|
1102 | send_release(server_addr, requested_ip); /* unicast */
|
---|
1103 | udhcp_run_script(NULL, "deconfig");
|
---|
1104 | }
|
---|
1105 | bb_info_msg("Entering released state");
|
---|
1106 |
|
---|
1107 | change_listen_mode(LISTEN_NONE);
|
---|
1108 | state = RELEASED;
|
---|
1109 | }
|
---|
1110 |
|
---|
1111 | static uint8_t* alloc_dhcp_option(int code, const char *str, int extra)
|
---|
1112 | {
|
---|
1113 | uint8_t *storage;
|
---|
1114 | int len = strnlen(str, 255);
|
---|
1115 | storage = xzalloc(len + extra + OPT_DATA);
|
---|
1116 | storage[OPT_CODE] = code;
|
---|
1117 | storage[OPT_LEN] = len + extra;
|
---|
1118 | memcpy(storage + extra + OPT_DATA, str, len);
|
---|
1119 | return storage;
|
---|
1120 | }
|
---|
1121 |
|
---|
1122 | #if BB_MMU
|
---|
1123 | static void client_background(void)
|
---|
1124 | {
|
---|
1125 | bb_daemonize(0);
|
---|
1126 | logmode &= ~LOGMODE_STDIO;
|
---|
1127 | /* rewrite pidfile, as our pid is different now */
|
---|
1128 | write_pidfile(client_config.pidfile);
|
---|
1129 | }
|
---|
1130 | #endif
|
---|
1131 |
|
---|
1132 | //usage:#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
|
---|
1133 | //usage:# define IF_UDHCP_VERBOSE(...) __VA_ARGS__
|
---|
1134 | //usage:#else
|
---|
1135 | //usage:# define IF_UDHCP_VERBOSE(...)
|
---|
1136 | //usage:#endif
|
---|
1137 | //usage:#define udhcpc_trivial_usage
|
---|
1138 | //usage: "[-fbnq"IF_UDHCP_VERBOSE("v")"oCRB] [-i IFACE] [-r IP] [-s PROG] [-p PIDFILE]\n"
|
---|
1139 | //usage: " [-V VENDOR] [-x OPT:VAL]... [-O OPT]..." IF_FEATURE_UDHCP_PORT(" [-P N]")
|
---|
1140 | //usage:#define udhcpc_full_usage "\n"
|
---|
1141 | //usage: IF_LONG_OPTS(
|
---|
1142 | //usage: "\n -i,--interface IFACE Interface to use (default eth0)"
|
---|
1143 | //usage: "\n -p,--pidfile FILE Create pidfile"
|
---|
1144 | //usage: "\n -s,--script PROG Run PROG at DHCP events (default "CONFIG_UDHCPC_DEFAULT_SCRIPT")"
|
---|
1145 | //usage: "\n -B,--broadcast Request broadcast replies"
|
---|
1146 | //usage: "\n -t,--retries N Send up to N discover packets"
|
---|
1147 | //usage: "\n -T,--timeout N Pause between packets (default 3 seconds)"
|
---|
1148 | //usage: "\n -A,--tryagain N Wait N seconds after failure (default 20)"
|
---|
1149 | //usage: "\n -f,--foreground Run in foreground"
|
---|
1150 | //usage: USE_FOR_MMU(
|
---|
1151 | //usage: "\n -b,--background Background if lease is not obtained"
|
---|
1152 | //usage: )
|
---|
1153 | //usage: "\n -n,--now Exit if lease is not obtained"
|
---|
1154 | //usage: "\n -q,--quit Exit after obtaining lease"
|
---|
1155 | //usage: "\n -R,--release Release IP on exit"
|
---|
1156 | //usage: "\n -S,--syslog Log to syslog too"
|
---|
1157 | //usage: IF_FEATURE_UDHCP_PORT(
|
---|
1158 | //usage: "\n -P,--client-port N Use port N (default 68)"
|
---|
1159 | //usage: )
|
---|
1160 | //usage: IF_FEATURE_UDHCPC_ARPING(
|
---|
1161 | //usage: "\n -a,--arping Use arping to validate offered address"
|
---|
1162 | //usage: )
|
---|
1163 | //usage: "\n -O,--request-option OPT Request option OPT from server (cumulative)"
|
---|
1164 | //usage: "\n -o,--no-default-options Don't request any options (unless -O is given)"
|
---|
1165 | //usage: "\n -r,--request IP Request this IP address"
|
---|
1166 | //usage: "\n -x OPT:VAL Include option OPT in sent packets (cumulative)"
|
---|
1167 | //usage: "\n Examples of string, numeric, and hex byte opts:"
|
---|
1168 | //usage: "\n -x hostname:bbox - option 12"
|
---|
1169 | //usage: "\n -x lease:3600 - option 51 (lease time)"
|
---|
1170 | //usage: "\n -x 0x3d:0100BEEFC0FFEE - option 61 (client id)"
|
---|
1171 | //usage: "\n -F,--fqdn NAME Ask server to update DNS mapping for NAME"
|
---|
1172 | //usage: "\n -V,--vendorclass VENDOR Vendor identifier (default 'udhcp VERSION')"
|
---|
1173 | //usage: "\n -C,--clientid-none Don't send MAC as client identifier"
|
---|
1174 | //usage: IF_UDHCP_VERBOSE(
|
---|
1175 | //usage: "\n -v Verbose"
|
---|
1176 | //usage: )
|
---|
1177 | //usage: )
|
---|
1178 | //usage: IF_NOT_LONG_OPTS(
|
---|
1179 | //usage: "\n -i IFACE Interface to use (default eth0)"
|
---|
1180 | //usage: "\n -p FILE Create pidfile"
|
---|
1181 | //usage: "\n -s PROG Run PROG at DHCP events (default "CONFIG_UDHCPC_DEFAULT_SCRIPT")"
|
---|
1182 | //usage: "\n -B Request broadcast replies"
|
---|
1183 | //usage: "\n -t N Send up to N discover packets"
|
---|
1184 | //usage: "\n -T N Pause between packets (default 3 seconds)"
|
---|
1185 | //usage: "\n -A N Wait N seconds (default 20) after failure"
|
---|
1186 | //usage: "\n -f Run in foreground"
|
---|
1187 | //usage: USE_FOR_MMU(
|
---|
1188 | //usage: "\n -b Background if lease is not obtained"
|
---|
1189 | //usage: )
|
---|
1190 | //usage: "\n -n Exit if lease is not obtained"
|
---|
1191 | //usage: "\n -q Exit after obtaining lease"
|
---|
1192 | //usage: "\n -R Release IP on exit"
|
---|
1193 | //usage: "\n -S Log to syslog too"
|
---|
1194 | //usage: IF_FEATURE_UDHCP_PORT(
|
---|
1195 | //usage: "\n -P N Use port N (default 68)"
|
---|
1196 | //usage: )
|
---|
1197 | //usage: IF_FEATURE_UDHCPC_ARPING(
|
---|
1198 | //usage: "\n -a Use arping to validate offered address"
|
---|
1199 | //usage: )
|
---|
1200 | //usage: "\n -O OPT Request option OPT from server (cumulative)"
|
---|
1201 | //usage: "\n -o Don't request any options (unless -O is given)"
|
---|
1202 | //usage: "\n -r IP Request this IP address"
|
---|
1203 | //usage: "\n -x OPT:VAL Include option OPT in sent packets (cumulative)"
|
---|
1204 | //usage: "\n Examples of string, numeric, and hex byte opts:"
|
---|
1205 | //usage: "\n -x hostname:bbox - option 12"
|
---|
1206 | //usage: "\n -x lease:3600 - option 51 (lease time)"
|
---|
1207 | //usage: "\n -x 0x3d:0100BEEFC0FFEE - option 61 (client id)"
|
---|
1208 | //usage: "\n -F NAME Ask server to update DNS mapping for NAME"
|
---|
1209 | //usage: "\n -V VENDOR Vendor identifier (default 'udhcp VERSION')"
|
---|
1210 | //usage: "\n -C Don't send MAC as client identifier"
|
---|
1211 | //usage: IF_UDHCP_VERBOSE(
|
---|
1212 | //usage: "\n -v Verbose"
|
---|
1213 | //usage: )
|
---|
1214 | //usage: )
|
---|
1215 | //usage: "\nSignals:"
|
---|
1216 | //usage: "\n USR1 Renew lease"
|
---|
1217 | //usage: "\n USR2 Release lease"
|
---|
1218 |
|
---|
1219 |
|
---|
1220 | int udhcpc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
|
---|
1221 | int udhcpc_main(int argc UNUSED_PARAM, char **argv)
|
---|
1222 | {
|
---|
1223 | uint8_t *temp, *message;
|
---|
1224 | const char *str_V, *str_h, *str_F, *str_r;
|
---|
1225 | IF_FEATURE_UDHCP_PORT(char *str_P;)
|
---|
1226 | void *clientid_mac_ptr;
|
---|
1227 | llist_t *list_O = NULL;
|
---|
1228 | llist_t *list_x = NULL;
|
---|
1229 | int tryagain_timeout = 20;
|
---|
1230 | int discover_timeout = 3;
|
---|
1231 | int discover_retries = 3;
|
---|
1232 | uint32_t server_addr = server_addr; /* for compiler */
|
---|
1233 | uint32_t requested_ip = 0;
|
---|
1234 | uint32_t xid = xid; /* for compiler */
|
---|
1235 | int packet_num;
|
---|
1236 | int timeout; /* must be signed */
|
---|
1237 | unsigned already_waited_sec;
|
---|
1238 | unsigned opt;
|
---|
1239 | int max_fd;
|
---|
1240 | int retval;
|
---|
1241 | fd_set rfds;
|
---|
1242 |
|
---|
1243 | /* Default options */
|
---|
1244 | IF_FEATURE_UDHCP_PORT(SERVER_PORT = 67;)
|
---|
1245 | IF_FEATURE_UDHCP_PORT(CLIENT_PORT = 68;)
|
---|
1246 | client_config.interface = "eth0";
|
---|
1247 | client_config.script = CONFIG_UDHCPC_DEFAULT_SCRIPT;
|
---|
1248 | str_V = "udhcp "BB_VER;
|
---|
1249 |
|
---|
1250 | /* Parse command line */
|
---|
1251 | /* O,x: list; -T,-t,-A take numeric param */
|
---|
1252 | opt_complementary = "O::x::T+:t+:A+" IF_UDHCP_VERBOSE(":vv") ;
|
---|
1253 | IF_LONG_OPTS(applet_long_options = udhcpc_longopts;)
|
---|
1254 | opt = getopt32(argv, "CV:H:h:F:i:np:qRr:s:T:t:SA:O:ox:fB"
|
---|
1255 | USE_FOR_MMU("b")
|
---|
1256 | IF_FEATURE_UDHCPC_ARPING("a")
|
---|
1257 | IF_FEATURE_UDHCP_PORT("P:")
|
---|
1258 | "v"
|
---|
1259 | , &str_V, &str_h, &str_h, &str_F
|
---|
1260 | , &client_config.interface, &client_config.pidfile, &str_r /* i,p */
|
---|
1261 | , &client_config.script /* s */
|
---|
1262 | , &discover_timeout, &discover_retries, &tryagain_timeout /* T,t,A */
|
---|
1263 | , &list_O
|
---|
1264 | , &list_x
|
---|
1265 | IF_FEATURE_UDHCP_PORT(, &str_P)
|
---|
1266 | IF_UDHCP_VERBOSE(, &dhcp_verbose)
|
---|
1267 | );
|
---|
1268 | if (opt & (OPT_h|OPT_H)) {
|
---|
1269 | //msg added 2011-11
|
---|
1270 | bb_error_msg("option -h NAME is deprecated, use -x hostname:NAME");
|
---|
1271 | client_config.hostname = alloc_dhcp_option(DHCP_HOST_NAME, str_h, 0);
|
---|
1272 | }
|
---|
1273 | if (opt & OPT_F) {
|
---|
1274 | /* FQDN option format: [0x51][len][flags][0][0]<fqdn> */
|
---|
1275 | client_config.fqdn = alloc_dhcp_option(DHCP_FQDN, str_F, 3);
|
---|
1276 | /* Flag bits: 0000NEOS
|
---|
1277 | * S: 1 = Client requests server to update A RR in DNS as well as PTR
|
---|
1278 | * O: 1 = Server indicates to client that DNS has been updated regardless
|
---|
1279 | * E: 1 = Name is in DNS format, i.e. <4>host<6>domain<3>com<0>,
|
---|
1280 | * not "host.domain.com". Format 0 is obsolete.
|
---|
1281 | * N: 1 = Client requests server to not update DNS (S must be 0 then)
|
---|
1282 | * Two [0] bytes which follow are deprecated and must be 0.
|
---|
1283 | */
|
---|
1284 | client_config.fqdn[OPT_DATA + 0] = 0x1;
|
---|
1285 | /*client_config.fqdn[OPT_DATA + 1] = 0; - xzalloc did it */
|
---|
1286 | /*client_config.fqdn[OPT_DATA + 2] = 0; */
|
---|
1287 | }
|
---|
1288 | if (opt & OPT_r)
|
---|
1289 | requested_ip = inet_addr(str_r);
|
---|
1290 | #if ENABLE_FEATURE_UDHCP_PORT
|
---|
1291 | if (opt & OPT_P) {
|
---|
1292 | CLIENT_PORT = xatou16(str_P);
|
---|
1293 | SERVER_PORT = CLIENT_PORT - 1;
|
---|
1294 | }
|
---|
1295 | #endif
|
---|
1296 | while (list_O) {
|
---|
1297 | char *optstr = llist_pop(&list_O);
|
---|
1298 | unsigned n = bb_strtou(optstr, NULL, 0);
|
---|
1299 | if (errno || n > 254) {
|
---|
1300 | n = udhcp_option_idx(optstr);
|
---|
1301 | n = dhcp_optflags[n].code;
|
---|
1302 | }
|
---|
1303 | client_config.opt_mask[n >> 3] |= 1 << (n & 7);
|
---|
1304 | }
|
---|
1305 | if (!(opt & OPT_o)) {
|
---|
1306 | unsigned i, n;
|
---|
1307 | for (i = 0; (n = dhcp_optflags[i].code) != 0; i++) {
|
---|
1308 | if (dhcp_optflags[i].flags & OPTION_REQ) {
|
---|
1309 | client_config.opt_mask[n >> 3] |= 1 << (n & 7);
|
---|
1310 | }
|
---|
1311 | }
|
---|
1312 | }
|
---|
1313 | while (list_x) {
|
---|
1314 | char *optstr = llist_pop(&list_x);
|
---|
1315 | char *colon = strchr(optstr, ':');
|
---|
1316 | if (colon)
|
---|
1317 | *colon = ' ';
|
---|
1318 | /* now it looks similar to udhcpd's config file line:
|
---|
1319 | * "optname optval", using the common routine: */
|
---|
1320 | udhcp_str2optset(optstr, &client_config.options);
|
---|
1321 | }
|
---|
1322 |
|
---|
1323 | if (udhcp_read_interface(client_config.interface,
|
---|
1324 | &client_config.ifindex,
|
---|
1325 | NULL,
|
---|
1326 | client_config.client_mac)
|
---|
1327 | ) {
|
---|
1328 | return 1;
|
---|
1329 | }
|
---|
1330 |
|
---|
1331 | clientid_mac_ptr = NULL;
|
---|
1332 | if (!(opt & OPT_C) && !udhcp_find_option(client_config.options, DHCP_CLIENT_ID)) {
|
---|
1333 | /* not suppressed and not set, set the default client ID */
|
---|
1334 | client_config.clientid = alloc_dhcp_option(DHCP_CLIENT_ID, "", 7);
|
---|
1335 | client_config.clientid[OPT_DATA] = 1; /* type: ethernet */
|
---|
1336 | clientid_mac_ptr = client_config.clientid + OPT_DATA+1;
|
---|
1337 | memcpy(clientid_mac_ptr, client_config.client_mac, 6);
|
---|
1338 | }
|
---|
1339 | if (str_V[0] != '\0') {
|
---|
1340 | // can drop -V, str_V, client_config.vendorclass,
|
---|
1341 | // but need to add "vendor" to the list of recognized
|
---|
1342 | // string opts for this to work;
|
---|
1343 | // and need to tweak add_client_options() too...
|
---|
1344 | // ...so the question is, should we?
|
---|
1345 | //bb_error_msg("option -V VENDOR is deprecated, use -x vendor:VENDOR");
|
---|
1346 | client_config.vendorclass = alloc_dhcp_option(DHCP_VENDOR, str_V, 0);
|
---|
1347 | }
|
---|
1348 |
|
---|
1349 | #if !BB_MMU
|
---|
1350 | /* on NOMMU reexec (i.e., background) early */
|
---|
1351 | if (!(opt & OPT_f)) {
|
---|
1352 | bb_daemonize_or_rexec(0 /* flags */, argv);
|
---|
1353 | logmode = LOGMODE_NONE;
|
---|
1354 | }
|
---|
1355 | #endif
|
---|
1356 | if (opt & OPT_S) {
|
---|
1357 | openlog(applet_name, LOG_PID, LOG_DAEMON);
|
---|
1358 | logmode |= LOGMODE_SYSLOG;
|
---|
1359 | }
|
---|
1360 |
|
---|
1361 | /* Make sure fd 0,1,2 are open */
|
---|
1362 | bb_sanitize_stdio();
|
---|
1363 | /* Equivalent of doing a fflush after every \n */
|
---|
1364 | setlinebuf(stdout);
|
---|
1365 | /* Create pidfile */
|
---|
1366 | write_pidfile(client_config.pidfile);
|
---|
1367 | /* Goes to stdout (unless NOMMU) and possibly syslog */
|
---|
1368 | bb_info_msg("%s (v"BB_VER") started", applet_name);
|
---|
1369 | /* Set up the signal pipe */
|
---|
1370 | udhcp_sp_setup();
|
---|
1371 | /* We want random_xid to be random... */
|
---|
1372 | srand(monotonic_us());
|
---|
1373 |
|
---|
1374 | state = INIT_SELECTING;
|
---|
1375 | udhcp_run_script(NULL, "deconfig");
|
---|
1376 | change_listen_mode(LISTEN_RAW);
|
---|
1377 | packet_num = 0;
|
---|
1378 | timeout = 0;
|
---|
1379 | already_waited_sec = 0;
|
---|
1380 |
|
---|
1381 | /* Main event loop. select() waits on signal pipe and possibly
|
---|
1382 | * on sockfd.
|
---|
1383 | * "continue" statements in code below jump to the top of the loop.
|
---|
1384 | */
|
---|
1385 | for (;;) {
|
---|
1386 | struct timeval tv;
|
---|
1387 | struct dhcp_packet packet;
|
---|
1388 | /* silence "uninitialized!" warning */
|
---|
1389 | unsigned timestamp_before_wait = timestamp_before_wait;
|
---|
1390 |
|
---|
1391 | //bb_error_msg("sockfd:%d, listen_mode:%d", sockfd, listen_mode);
|
---|
1392 |
|
---|
1393 | /* Was opening raw or udp socket here
|
---|
1394 | * if (listen_mode != LISTEN_NONE && sockfd < 0),
|
---|
1395 | * but on fast network renew responses return faster
|
---|
1396 | * than we open sockets. Thus this code is moved
|
---|
1397 | * to change_listen_mode(). Thus we open listen socket
|
---|
1398 | * BEFORE we send renew request (see "case BOUND:"). */
|
---|
1399 |
|
---|
1400 | max_fd = udhcp_sp_fd_set(&rfds, sockfd);
|
---|
1401 |
|
---|
1402 | tv.tv_sec = timeout - already_waited_sec;
|
---|
1403 | tv.tv_usec = 0;
|
---|
1404 | retval = 0;
|
---|
1405 | /* If we already timed out, fall through with retval = 0, else... */
|
---|
1406 | if ((int)tv.tv_sec > 0) {
|
---|
1407 | log1("Waiting on select %u seconds", (int)tv.tv_sec);
|
---|
1408 | timestamp_before_wait = (unsigned)monotonic_sec();
|
---|
1409 | retval = select(max_fd + 1, &rfds, NULL, NULL, &tv);
|
---|
1410 | if (retval < 0) {
|
---|
1411 | /* EINTR? A signal was caught, don't panic */
|
---|
1412 | if (errno == EINTR) {
|
---|
1413 | already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
|
---|
1414 | continue;
|
---|
1415 | }
|
---|
1416 | /* Else: an error occured, panic! */
|
---|
1417 | bb_perror_msg_and_die("select");
|
---|
1418 | }
|
---|
1419 | }
|
---|
1420 |
|
---|
1421 | /* If timeout dropped to zero, time to become active:
|
---|
1422 | * resend discover/renew/whatever
|
---|
1423 | */
|
---|
1424 | if (retval == 0) {
|
---|
1425 | /* When running on a bridge, the ifindex may have changed
|
---|
1426 | * (e.g. if member interfaces were added/removed
|
---|
1427 | * or if the status of the bridge changed).
|
---|
1428 | * Refresh ifindex and client_mac:
|
---|
1429 | */
|
---|
1430 | if (udhcp_read_interface(client_config.interface,
|
---|
1431 | &client_config.ifindex,
|
---|
1432 | NULL,
|
---|
1433 | client_config.client_mac)
|
---|
1434 | ) {
|
---|
1435 | goto ret0; /* iface is gone? */
|
---|
1436 | }
|
---|
1437 | if (clientid_mac_ptr)
|
---|
1438 | memcpy(clientid_mac_ptr, client_config.client_mac, 6);
|
---|
1439 |
|
---|
1440 | /* We will restart the wait in any case */
|
---|
1441 | already_waited_sec = 0;
|
---|
1442 |
|
---|
1443 | switch (state) {
|
---|
1444 | case INIT_SELECTING:
|
---|
1445 | if (!discover_retries || packet_num < discover_retries) {
|
---|
1446 | if (packet_num == 0)
|
---|
1447 | xid = random_xid();
|
---|
1448 | /* broadcast */
|
---|
1449 | send_discover(xid, requested_ip);
|
---|
1450 | timeout = discover_timeout;
|
---|
1451 | packet_num++;
|
---|
1452 | continue;
|
---|
1453 | }
|
---|
1454 | leasefail:
|
---|
1455 | udhcp_run_script(NULL, "leasefail");
|
---|
1456 | #if BB_MMU /* -b is not supported on NOMMU */
|
---|
1457 | if (opt & OPT_b) { /* background if no lease */
|
---|
1458 | bb_info_msg("No lease, forking to background");
|
---|
1459 | client_background();
|
---|
1460 | /* do not background again! */
|
---|
1461 | opt = ((opt & ~OPT_b) | OPT_f);
|
---|
1462 | } else
|
---|
1463 | #endif
|
---|
1464 | if (opt & OPT_n) { /* abort if no lease */
|
---|
1465 | bb_info_msg("No lease, failing");
|
---|
1466 | retval = 1;
|
---|
1467 | goto ret;
|
---|
1468 | }
|
---|
1469 | /* wait before trying again */
|
---|
1470 | timeout = tryagain_timeout;
|
---|
1471 | packet_num = 0;
|
---|
1472 | continue;
|
---|
1473 | case REQUESTING:
|
---|
1474 | if (!discover_retries || packet_num < discover_retries) {
|
---|
1475 | /* send broadcast select packet */
|
---|
1476 | send_select(xid, server_addr, requested_ip);
|
---|
1477 | timeout = discover_timeout;
|
---|
1478 | packet_num++;
|
---|
1479 | continue;
|
---|
1480 | }
|
---|
1481 | /* Timed out, go back to init state.
|
---|
1482 | * "discover...select...discover..." loops
|
---|
1483 | * were seen in the wild. Treat them similarly
|
---|
1484 | * to "no response to discover" case */
|
---|
1485 | change_listen_mode(LISTEN_RAW);
|
---|
1486 | state = INIT_SELECTING;
|
---|
1487 | goto leasefail;
|
---|
1488 | case BOUND:
|
---|
1489 | /* 1/2 lease passed, enter renewing state */
|
---|
1490 | state = RENEWING;
|
---|
1491 | client_config.first_secs = 0; /* make secs field count from 0 */
|
---|
1492 | change_listen_mode(LISTEN_KERNEL);
|
---|
1493 | log1("Entering renew state");
|
---|
1494 | /* fall right through */
|
---|
1495 | case RENEW_REQUESTED: /* manual (SIGUSR1) renew */
|
---|
1496 | case_RENEW_REQUESTED:
|
---|
1497 | case RENEWING:
|
---|
1498 | if (timeout > 60) {
|
---|
1499 | /* send an unicast renew request */
|
---|
1500 | /* Sometimes observed to fail (EADDRNOTAVAIL) to bind
|
---|
1501 | * a new UDP socket for sending inside send_renew.
|
---|
1502 | * I hazard to guess existing listening socket
|
---|
1503 | * is somehow conflicting with it, but why is it
|
---|
1504 | * not deterministic then?! Strange.
|
---|
1505 | * Anyway, it does recover by eventually failing through
|
---|
1506 | * into INIT_SELECTING state.
|
---|
1507 | */
|
---|
1508 | send_renew(xid, server_addr, requested_ip);
|
---|
1509 | timeout >>= 1;
|
---|
1510 | continue;
|
---|
1511 | }
|
---|
1512 | /* Timed out, enter rebinding state */
|
---|
1513 | log1("Entering rebinding state");
|
---|
1514 | state = REBINDING;
|
---|
1515 | /* fall right through */
|
---|
1516 | case REBINDING:
|
---|
1517 | /* Switch to bcast receive */
|
---|
1518 | change_listen_mode(LISTEN_RAW);
|
---|
1519 | /* Lease is *really* about to run out,
|
---|
1520 | * try to find DHCP server using broadcast */
|
---|
1521 | if (timeout > 0) {
|
---|
1522 | /* send a broadcast renew request */
|
---|
1523 | send_renew(xid, 0 /*INADDR_ANY*/, requested_ip);
|
---|
1524 | timeout >>= 1;
|
---|
1525 | continue;
|
---|
1526 | }
|
---|
1527 | /* Timed out, enter init state */
|
---|
1528 | bb_info_msg("Lease lost, entering init state");
|
---|
1529 | udhcp_run_script(NULL, "deconfig");
|
---|
1530 | state = INIT_SELECTING;
|
---|
1531 | client_config.first_secs = 0; /* make secs field count from 0 */
|
---|
1532 | /*timeout = 0; - already is */
|
---|
1533 | packet_num = 0;
|
---|
1534 | continue;
|
---|
1535 | /* case RELEASED: */
|
---|
1536 | }
|
---|
1537 | /* yah, I know, *you* say it would never happen */
|
---|
1538 | timeout = INT_MAX;
|
---|
1539 | continue; /* back to main loop */
|
---|
1540 | } /* if select timed out */
|
---|
1541 |
|
---|
1542 | /* select() didn't timeout, something happened */
|
---|
1543 |
|
---|
1544 | /* Is it a signal? */
|
---|
1545 | /* note: udhcp_sp_read checks FD_ISSET before reading */
|
---|
1546 | switch (udhcp_sp_read(&rfds)) {
|
---|
1547 | case SIGUSR1:
|
---|
1548 | client_config.first_secs = 0; /* make secs field count from 0 */
|
---|
1549 | already_waited_sec = 0;
|
---|
1550 | perform_renew();
|
---|
1551 | if (state == RENEW_REQUESTED) {
|
---|
1552 | /* We might be either on the same network
|
---|
1553 | * (in which case renew might work),
|
---|
1554 | * or we might be on a completely different one
|
---|
1555 | * (in which case renew won't ever succeed).
|
---|
1556 | * For the second case, must make sure timeout
|
---|
1557 | * is not too big, or else we can send
|
---|
1558 | * futile renew requests for hours.
|
---|
1559 | * (Ab)use -A TIMEOUT value (usually 20 sec)
|
---|
1560 | * as a cap on the timeout.
|
---|
1561 | */
|
---|
1562 | if (timeout > tryagain_timeout)
|
---|
1563 | timeout = tryagain_timeout;
|
---|
1564 | goto case_RENEW_REQUESTED;
|
---|
1565 | }
|
---|
1566 | /* Start things over */
|
---|
1567 | packet_num = 0;
|
---|
1568 | /* Kill any timeouts, user wants this to hurry along */
|
---|
1569 | timeout = 0;
|
---|
1570 | continue;
|
---|
1571 | case SIGUSR2:
|
---|
1572 | perform_release(server_addr, requested_ip);
|
---|
1573 | timeout = INT_MAX;
|
---|
1574 | continue;
|
---|
1575 | case SIGTERM:
|
---|
1576 | bb_info_msg("Received SIGTERM");
|
---|
1577 | goto ret0;
|
---|
1578 | }
|
---|
1579 |
|
---|
1580 | /* Is it a packet? */
|
---|
1581 | if (listen_mode == LISTEN_NONE || !FD_ISSET(sockfd, &rfds))
|
---|
1582 | continue; /* no */
|
---|
1583 |
|
---|
1584 | {
|
---|
1585 | int len;
|
---|
1586 |
|
---|
1587 | /* A packet is ready, read it */
|
---|
1588 | if (listen_mode == LISTEN_KERNEL)
|
---|
1589 | len = udhcp_recv_kernel_packet(&packet, sockfd);
|
---|
1590 | else
|
---|
1591 | len = udhcp_recv_raw_packet(&packet, sockfd);
|
---|
1592 | if (len == -1) {
|
---|
1593 | /* Error is severe, reopen socket */
|
---|
1594 | bb_info_msg("Read error: %s, reopening socket", strerror(errno));
|
---|
1595 | sleep(discover_timeout); /* 3 seconds by default */
|
---|
1596 | change_listen_mode(listen_mode); /* just close and reopen */
|
---|
1597 | }
|
---|
1598 | /* If this packet will turn out to be unrelated/bogus,
|
---|
1599 | * we will go back and wait for next one.
|
---|
1600 | * Be sure timeout is properly decreased. */
|
---|
1601 | already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
|
---|
1602 | if (len < 0)
|
---|
1603 | continue;
|
---|
1604 | }
|
---|
1605 |
|
---|
1606 | if (packet.xid != xid) {
|
---|
1607 | log1("xid %x (our is %x), ignoring packet",
|
---|
1608 | (unsigned)packet.xid, (unsigned)xid);
|
---|
1609 | continue;
|
---|
1610 | }
|
---|
1611 |
|
---|
1612 | /* Ignore packets that aren't for us */
|
---|
1613 | if (packet.hlen != 6
|
---|
1614 | || memcmp(packet.chaddr, client_config.client_mac, 6) != 0
|
---|
1615 | ) {
|
---|
1616 | //FIXME: need to also check that last 10 bytes are zero
|
---|
1617 | log1("chaddr does not match, ignoring packet"); // log2?
|
---|
1618 | continue;
|
---|
1619 | }
|
---|
1620 |
|
---|
1621 | message = udhcp_get_option(&packet, DHCP_MESSAGE_TYPE);
|
---|
1622 | if (message == NULL) {
|
---|
1623 | bb_error_msg("no message type option, ignoring packet");
|
---|
1624 | continue;
|
---|
1625 | }
|
---|
1626 |
|
---|
1627 | switch (state) {
|
---|
1628 | case INIT_SELECTING:
|
---|
1629 | /* Must be a DHCPOFFER */
|
---|
1630 | if (*message == DHCPOFFER) {
|
---|
1631 | /* What exactly is server's IP? There are several values.
|
---|
1632 | * Example DHCP offer captured with tchdump:
|
---|
1633 | *
|
---|
1634 | * 10.34.25.254:67 > 10.34.25.202:68 // IP header's src
|
---|
1635 | * BOOTP fields:
|
---|
1636 | * Your-IP 10.34.25.202
|
---|
1637 | * Server-IP 10.34.32.125 // "next server" IP
|
---|
1638 | * Gateway-IP 10.34.25.254 // relay's address (if DHCP relays are in use)
|
---|
1639 | * DHCP options:
|
---|
1640 | * DHCP-Message Option 53, length 1: Offer
|
---|
1641 | * Server-ID Option 54, length 4: 10.34.255.7 // "server ID"
|
---|
1642 | * Default-Gateway Option 3, length 4: 10.34.25.254 // router
|
---|
1643 | *
|
---|
1644 | * We think that real server IP (one to use in renew/release)
|
---|
1645 | * is one in Server-ID option. But I am not 100% sure.
|
---|
1646 | * IP header's src and Gateway-IP (same in this example)
|
---|
1647 | * might work too.
|
---|
1648 | * "Next server" and router are definitely wrong ones to use, though...
|
---|
1649 | */
|
---|
1650 | temp = udhcp_get_option(&packet, DHCP_SERVER_ID);
|
---|
1651 | if (!temp) {
|
---|
1652 | bb_error_msg("no server ID, ignoring packet");
|
---|
1653 | continue;
|
---|
1654 | /* still selecting - this server looks bad */
|
---|
1655 | }
|
---|
1656 | /* it IS unaligned sometimes, don't "optimize" */
|
---|
1657 | move_from_unaligned32(server_addr, temp);
|
---|
1658 | /*xid = packet.xid; - already is */
|
---|
1659 | requested_ip = packet.yiaddr;
|
---|
1660 |
|
---|
1661 | /* enter requesting state */
|
---|
1662 | state = REQUESTING;
|
---|
1663 | timeout = 0;
|
---|
1664 | packet_num = 0;
|
---|
1665 | already_waited_sec = 0;
|
---|
1666 | }
|
---|
1667 | continue;
|
---|
1668 | case REQUESTING:
|
---|
1669 | case RENEWING:
|
---|
1670 | case RENEW_REQUESTED:
|
---|
1671 | case REBINDING:
|
---|
1672 | if (*message == DHCPACK) {
|
---|
1673 | uint32_t lease_seconds;
|
---|
1674 | struct in_addr temp_addr;
|
---|
1675 |
|
---|
1676 | temp = udhcp_get_option(&packet, DHCP_LEASE_TIME);
|
---|
1677 | if (!temp) {
|
---|
1678 | bb_error_msg("no lease time with ACK, using 1 hour lease");
|
---|
1679 | lease_seconds = 60 * 60;
|
---|
1680 | } else {
|
---|
1681 | /* it IS unaligned sometimes, don't "optimize" */
|
---|
1682 | move_from_unaligned32(lease_seconds, temp);
|
---|
1683 | lease_seconds = ntohl(lease_seconds);
|
---|
1684 | /* paranoia: must not be too small and not prone to overflows */
|
---|
1685 | if (lease_seconds < 0x10)
|
---|
1686 | lease_seconds = 0x10;
|
---|
1687 | if (lease_seconds >= 0x10000000)
|
---|
1688 | lease_seconds = 0x0fffffff;
|
---|
1689 | }
|
---|
1690 | #if ENABLE_FEATURE_UDHCPC_ARPING
|
---|
1691 | if (opt & OPT_a) {
|
---|
1692 | /* RFC 2131 3.1 paragraph 5:
|
---|
1693 | * "The client receives the DHCPACK message with configuration
|
---|
1694 | * parameters. The client SHOULD perform a final check on the
|
---|
1695 | * parameters (e.g., ARP for allocated network address), and notes
|
---|
1696 | * the duration of the lease specified in the DHCPACK message. At this
|
---|
1697 | * point, the client is configured. If the client detects that the
|
---|
1698 | * address is already in use (e.g., through the use of ARP),
|
---|
1699 | * the client MUST send a DHCPDECLINE message to the server and restarts
|
---|
1700 | * the configuration process..." */
|
---|
1701 | if (!arpping(packet.yiaddr,
|
---|
1702 | NULL,
|
---|
1703 | (uint32_t) 0,
|
---|
1704 | client_config.client_mac,
|
---|
1705 | client_config.interface)
|
---|
1706 | ) {
|
---|
1707 | bb_info_msg("Offered address is in use "
|
---|
1708 | "(got ARP reply), declining");
|
---|
1709 | send_decline(/*xid,*/ server_addr, packet.yiaddr);
|
---|
1710 |
|
---|
1711 | if (state != REQUESTING)
|
---|
1712 | udhcp_run_script(NULL, "deconfig");
|
---|
1713 | change_listen_mode(LISTEN_RAW);
|
---|
1714 | state = INIT_SELECTING;
|
---|
1715 | client_config.first_secs = 0; /* make secs field count from 0 */
|
---|
1716 | requested_ip = 0;
|
---|
1717 | timeout = tryagain_timeout;
|
---|
1718 | packet_num = 0;
|
---|
1719 | already_waited_sec = 0;
|
---|
1720 | continue; /* back to main loop */
|
---|
1721 | }
|
---|
1722 | }
|
---|
1723 | #endif
|
---|
1724 | /* enter bound state */
|
---|
1725 | timeout = lease_seconds / 2;
|
---|
1726 | temp_addr.s_addr = packet.yiaddr;
|
---|
1727 | bb_info_msg("Lease of %s obtained, lease time %u",
|
---|
1728 | inet_ntoa(temp_addr), (unsigned)lease_seconds);
|
---|
1729 | requested_ip = packet.yiaddr;
|
---|
1730 | udhcp_run_script(&packet, state == REQUESTING ? "bound" : "renew");
|
---|
1731 |
|
---|
1732 | state = BOUND;
|
---|
1733 | change_listen_mode(LISTEN_NONE);
|
---|
1734 | if (opt & OPT_q) { /* quit after lease */
|
---|
1735 | goto ret0;
|
---|
1736 | }
|
---|
1737 | /* future renew failures should not exit (JM) */
|
---|
1738 | opt &= ~OPT_n;
|
---|
1739 | #if BB_MMU /* NOMMU case backgrounded earlier */
|
---|
1740 | if (!(opt & OPT_f)) {
|
---|
1741 | client_background();
|
---|
1742 | /* do not background again! */
|
---|
1743 | opt = ((opt & ~OPT_b) | OPT_f);
|
---|
1744 | }
|
---|
1745 | #endif
|
---|
1746 | /* make future renew packets use different xid */
|
---|
1747 | /* xid = random_xid(); ...but why bother? */
|
---|
1748 | already_waited_sec = 0;
|
---|
1749 | continue; /* back to main loop */
|
---|
1750 | }
|
---|
1751 | if (*message == DHCPNAK) {
|
---|
1752 | /* return to init state */
|
---|
1753 | bb_info_msg("Received DHCP NAK");
|
---|
1754 | udhcp_run_script(&packet, "nak");
|
---|
1755 | if (state != REQUESTING)
|
---|
1756 | udhcp_run_script(NULL, "deconfig");
|
---|
1757 | change_listen_mode(LISTEN_RAW);
|
---|
1758 | sleep(3); /* avoid excessive network traffic */
|
---|
1759 | state = INIT_SELECTING;
|
---|
1760 | client_config.first_secs = 0; /* make secs field count from 0 */
|
---|
1761 | requested_ip = 0;
|
---|
1762 | timeout = 0;
|
---|
1763 | packet_num = 0;
|
---|
1764 | already_waited_sec = 0;
|
---|
1765 | }
|
---|
1766 | continue;
|
---|
1767 | /* case BOUND: - ignore all packets */
|
---|
1768 | /* case RELEASED: - ignore all packets */
|
---|
1769 | }
|
---|
1770 | /* back to main loop */
|
---|
1771 | } /* for (;;) - main loop ends */
|
---|
1772 |
|
---|
1773 | ret0:
|
---|
1774 | if (opt & OPT_R) /* release on quit */
|
---|
1775 | perform_release(server_addr, requested_ip);
|
---|
1776 | retval = 0;
|
---|
1777 | ret:
|
---|
1778 | /*if (client_config.pidfile) - remove_pidfile has its own check */
|
---|
1779 | remove_pidfile(client_config.pidfile);
|
---|
1780 | return retval;
|
---|
1781 | }
|
---|