1 | /* script.c
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2 | *
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3 | * Functions to call the DHCP client notification scripts
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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 | * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
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8 | */
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9 |
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10 | #include <string.h>
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11 | #include <unistd.h>
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12 | #include <stdio.h>
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13 | #include <stdlib.h>
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14 | #include <sys/socket.h>
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15 | #include <netinet/in.h>
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16 | #include <arpa/inet.h>
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17 | #include <sys/types.h>
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18 | #include <sys/wait.h>
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19 |
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20 | #include "common.h"
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21 | #include "options.h"
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22 | #include "dhcpd.h"
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23 | #include "dhcpc.h"
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24 |
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25 | /* get a rough idea of how long an option will be (rounding up...) */
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26 | static const int max_option_length[] = {
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27 | [OPTION_IP] = sizeof("255.255.255.255 "),
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28 | [OPTION_IP_PAIR] = sizeof("255.255.255.255 ") * 2,
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29 | [OPTION_STRING] = 1,
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30 | [OPTION_BOOLEAN] = sizeof("yes "),
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31 | [OPTION_U8] = sizeof("255 "),
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32 | [OPTION_U16] = sizeof("65535 "),
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33 | [OPTION_S16] = sizeof("-32768 "),
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34 | [OPTION_U32] = sizeof("4294967295 "),
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35 | [OPTION_S32] = sizeof("-2147483684 "),
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36 | };
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37 |
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38 |
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39 | static inline int upper_length(int length, int opt_index)
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40 | {
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41 | return max_option_length[opt_index] *
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42 | (length / option_lengths[opt_index]);
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43 | }
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44 |
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45 |
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46 | static int sprintip(char *dest, char *pre, uint8_t *ip)
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47 | {
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48 | return sprintf(dest, "%s%d.%d.%d.%d", pre, ip[0], ip[1], ip[2], ip[3]);
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49 | }
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50 |
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51 |
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52 | /* really simple implementation, just count the bits */
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53 | static int mton(struct in_addr *mask)
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54 | {
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55 | int i;
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56 | unsigned long bits = ntohl(mask->s_addr);
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57 | /* too bad one can't check the carry bit, etc in c bit
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58 | * shifting */
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59 | for (i = 0; i < 32 && !((bits >> i) & 1); i++);
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60 | return 32 - i;
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61 | }
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62 |
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63 |
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64 | /* Fill dest with the text of option 'option'. */
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65 | static void fill_options(char *dest, uint8_t *option, struct dhcp_option *type_p)
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66 | {
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67 | int type, optlen;
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68 | uint16_t val_u16;
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69 | int16_t val_s16;
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70 | uint32_t val_u32;
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71 | int32_t val_s32;
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72 | int len = option[OPT_LEN - 2];
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73 |
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74 | dest += sprintf(dest, "%s=", type_p->name);
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75 |
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76 | type = type_p->flags & TYPE_MASK;
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77 | optlen = option_lengths[type];
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78 | for(;;) {
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79 | switch (type) {
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80 | case OPTION_IP_PAIR:
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81 | dest += sprintip(dest, "", option);
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82 | *(dest++) = '/';
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83 | option += 4;
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84 | optlen = 4;
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85 | case OPTION_IP: /* Works regardless of host byte order. */
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86 | dest += sprintip(dest, "", option);
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87 | break;
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88 | case OPTION_BOOLEAN:
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89 | dest += sprintf(dest, *option ? "yes" : "no");
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90 | break;
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91 | case OPTION_U8:
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92 | dest += sprintf(dest, "%u", *option);
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93 | break;
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94 | case OPTION_U16:
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95 | memcpy(&val_u16, option, 2);
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96 | dest += sprintf(dest, "%u", ntohs(val_u16));
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97 | break;
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98 | case OPTION_S16:
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99 | memcpy(&val_s16, option, 2);
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100 | dest += sprintf(dest, "%d", ntohs(val_s16));
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101 | break;
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102 | case OPTION_U32:
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103 | memcpy(&val_u32, option, 4);
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104 | dest += sprintf(dest, "%lu", (unsigned long) ntohl(val_u32));
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105 | break;
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106 | case OPTION_S32:
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107 | memcpy(&val_s32, option, 4);
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108 | dest += sprintf(dest, "%ld", (long) ntohl(val_s32));
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109 | break;
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110 | case OPTION_STRING:
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111 | memcpy(dest, option, len);
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112 | dest[len] = '\0';
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113 | return; /* Short circuit this case */
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114 | }
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115 | option += optlen;
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116 | len -= optlen;
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117 | if (len <= 0) break;
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118 | dest += sprintf(dest, " ");
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119 | }
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120 | }
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121 |
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122 |
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123 | /* put all the parameters into an environment */
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124 | static char **fill_envp(struct dhcpMessage *packet)
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125 | {
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126 | int num_options = 0;
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127 | int i, j;
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128 | char **envp;
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129 | uint8_t *temp;
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130 | struct in_addr subnet;
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131 | char over = 0;
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132 |
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133 | if (packet == NULL)
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134 | num_options = 0;
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135 | else {
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136 | for (i = 0; dhcp_options[i].code; i++)
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137 | if (get_option(packet, dhcp_options[i].code)) {
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138 | num_options++;
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139 | if (dhcp_options[i].code == DHCP_SUBNET)
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140 | num_options++; /* for mton */
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141 | }
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142 | if (packet->siaddr) num_options++;
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143 | if ((temp = get_option(packet, DHCP_OPTION_OVER)))
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144 | over = *temp;
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145 | if (!(over & FILE_FIELD) && packet->file[0]) num_options++;
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146 | if (!(over & SNAME_FIELD) && packet->sname[0]) num_options++;
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147 | }
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148 |
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149 | envp = xzalloc(sizeof(char *) * (num_options + 5));
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150 | j = 0;
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151 | envp[j++] = bb_xasprintf("interface=%s", client_config.interface);
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152 | envp[j++] = bb_xasprintf("PATH=%s",
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153 | getenv("PATH") ? : "/bin:/usr/bin:/sbin:/usr/sbin");
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154 | envp[j++] = bb_xasprintf("HOME=%s", getenv("HOME") ? : "/");
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155 |
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156 | if (packet == NULL) return envp;
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157 |
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158 | envp[j] = xmalloc(sizeof("ip=255.255.255.255"));
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159 | sprintip(envp[j++], "ip=", (uint8_t *) &packet->yiaddr);
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160 |
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161 |
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162 | for (i = 0; dhcp_options[i].code; i++) {
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163 | if (!(temp = get_option(packet, dhcp_options[i].code)))
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164 | continue;
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165 | envp[j] = xmalloc(upper_length(temp[OPT_LEN - 2],
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166 | dhcp_options[i].flags & TYPE_MASK) + strlen(dhcp_options[i].name) + 2);
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167 | fill_options(envp[j++], temp, &dhcp_options[i]);
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168 |
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169 | /* Fill in a subnet bits option for things like /24 */
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170 | if (dhcp_options[i].code == DHCP_SUBNET) {
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171 | memcpy(&subnet, temp, 4);
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172 | envp[j++] = bb_xasprintf("mask=%d", mton(&subnet));
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173 | }
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174 | }
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175 | if (packet->siaddr) {
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176 | envp[j] = xmalloc(sizeof("siaddr=255.255.255.255"));
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177 | sprintip(envp[j++], "siaddr=", (uint8_t *) &packet->siaddr);
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178 | }
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179 | if (!(over & FILE_FIELD) && packet->file[0]) {
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180 | /* watch out for invalid packets */
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181 | packet->file[sizeof(packet->file) - 1] = '\0';
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182 | envp[j++] = bb_xasprintf("boot_file=%s", packet->file);
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183 | }
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184 | if (!(over & SNAME_FIELD) && packet->sname[0]) {
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185 | /* watch out for invalid packets */
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186 | packet->sname[sizeof(packet->sname) - 1] = '\0';
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187 | envp[j++] = bb_xasprintf("sname=%s", packet->sname);
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188 | }
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189 | return envp;
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190 | }
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191 |
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192 |
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193 | /* Call a script with a par file and env vars */
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194 | void udhcp_run_script(struct dhcpMessage *packet, const char *name)
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195 | {
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196 | int pid;
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197 | char **envp, **curr;
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198 |
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199 | if (client_config.script == NULL)
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200 | return;
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201 |
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202 | DEBUG(LOG_INFO, "vforking and execle'ing %s", client_config.script);
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203 |
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204 | envp = fill_envp(packet);
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205 | /* call script */
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206 | pid = vfork();
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207 | if (pid) {
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208 | waitpid(pid, NULL, 0);
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209 | for (curr = envp; *curr; curr++) free(*curr);
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210 | free(envp);
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211 | return;
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212 | } else if (pid == 0) {
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213 | /* close fd's? */
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214 |
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215 | /* exec script */
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216 | execle(client_config.script, client_config.script,
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217 | name, NULL, envp);
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218 | LOG(LOG_ERR, "script %s failed: %m", client_config.script);
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219 | exit(1);
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220 | }
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221 | }
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