1 | /* vi: set sw=4 ts=4: */
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2 | /* script.c
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3 | *
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4 | * Functions to call the DHCP client notification scripts
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5 | *
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6 | * Russ Dill <Russ.Dill@asu.edu> July 2001
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7 | *
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8 | * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
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9 | */
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10 |
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11 | #include "common.h"
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12 | #include "dhcpc.h"
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13 | #include "options.h"
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14 |
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15 |
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16 | /* get a rough idea of how long an option will be (rounding up...) */
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17 | static const uint8_t max_option_length[] = {
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18 | [OPTION_IP] = sizeof("255.255.255.255 "),
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19 | [OPTION_IP_PAIR] = sizeof("255.255.255.255 ") * 2,
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20 | [OPTION_STRING] = 1,
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21 | #if ENABLE_FEATURE_RFC3397
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22 | [OPTION_STR1035] = 1,
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23 | #endif
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24 | [OPTION_BOOLEAN] = sizeof("yes "),
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25 | [OPTION_U8] = sizeof("255 "),
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26 | [OPTION_U16] = sizeof("65535 "),
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27 | [OPTION_S16] = sizeof("-32768 "),
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28 | [OPTION_U32] = sizeof("4294967295 "),
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29 | [OPTION_S32] = sizeof("-2147483684 "),
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30 | };
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31 |
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32 |
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33 | static inline int upper_length(int length, int opt_index)
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34 | {
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35 | return max_option_length[opt_index] *
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36 | (length / option_lengths[opt_index]);
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37 | }
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38 |
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39 |
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40 | static int sprintip(char *dest, const char *pre, const uint8_t *ip)
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41 | {
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42 | return sprintf(dest, "%s%d.%d.%d.%d", pre, ip[0], ip[1], ip[2], ip[3]);
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43 | }
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44 |
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45 |
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46 | /* really simple implementation, just count the bits */
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47 | static int mton(struct in_addr *mask)
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48 | {
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49 | int i;
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50 | unsigned long bits = ntohl(mask->s_addr);
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51 | /* too bad one can't check the carry bit, etc in c bit
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52 | * shifting */
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53 | for (i = 0; i < 32 && !((bits >> i) & 1); i++);
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54 | return 32 - i;
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55 | }
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56 |
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57 |
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58 | /* Allocate and fill with the text of option 'option'. */
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59 | static char *alloc_fill_opts(uint8_t *option, const struct dhcp_option *type_p)
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60 | {
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61 | int len, type, optlen;
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62 | uint16_t val_u16;
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63 | int16_t val_s16;
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64 | uint32_t val_u32;
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65 | int32_t val_s32;
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66 | char *dest, *ret;
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67 |
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68 | len = option[OPT_LEN - 2];
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69 | type = type_p->flags & TYPE_MASK;
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70 | optlen = option_lengths[type];
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71 |
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72 | dest = ret = xmalloc(upper_length(len, type) + strlen(type_p->name) + 2);
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73 | dest += sprintf(ret, "%s=", type_p->name);
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74 |
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75 | for (;;) {
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76 | switch (type) {
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77 | case OPTION_IP_PAIR:
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78 | dest += sprintip(dest, "", option);
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79 | *dest++ = '/';
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80 | option += 4;
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81 | optlen = 4;
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82 | case OPTION_IP: /* Works regardless of host byte order. */
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83 | dest += sprintip(dest, "", option);
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84 | break;
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85 | case OPTION_BOOLEAN:
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86 | dest += sprintf(dest, *option ? "yes" : "no");
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87 | break;
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88 | case OPTION_U8:
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89 | dest += sprintf(dest, "%u", *option);
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90 | break;
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91 | case OPTION_U16:
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92 | memcpy(&val_u16, option, 2);
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93 | dest += sprintf(dest, "%u", ntohs(val_u16));
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94 | break;
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95 | case OPTION_S16:
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96 | memcpy(&val_s16, option, 2);
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97 | dest += sprintf(dest, "%d", ntohs(val_s16));
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98 | break;
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99 | case OPTION_U32:
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100 | memcpy(&val_u32, option, 4);
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101 | dest += sprintf(dest, "%lu", (unsigned long) ntohl(val_u32));
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102 | break;
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103 | case OPTION_S32:
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104 | memcpy(&val_s32, option, 4);
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105 | dest += sprintf(dest, "%ld", (long) ntohl(val_s32));
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106 | break;
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107 | case OPTION_STRING:
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108 | memcpy(dest, option, len);
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109 | dest[len] = '\0';
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110 | return ret; /* Short circuit this case */
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111 | #if ENABLE_FEATURE_RFC3397
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112 | case OPTION_STR1035:
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113 | /* unpack option into dest; use ret for prefix (i.e., "optname=") */
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114 | dest = dname_dec(option, len, ret);
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115 | free(ret);
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116 | return dest;
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117 | #endif
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118 | }
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119 | option += optlen;
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120 | len -= optlen;
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121 | if (len <= 0) break;
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122 | dest += sprintf(dest, " ");
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123 | }
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124 | return ret;
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125 | }
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126 |
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127 |
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128 | /* put all the parameters into an environment */
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129 | static char **fill_envp(struct dhcpMessage *packet)
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130 | {
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131 | int num_options = 0;
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132 | int i, j;
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133 | char **envp;
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134 | char *var;
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135 | uint8_t *temp;
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136 | struct in_addr subnet;
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137 | char over = 0;
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138 |
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139 | if (packet) {
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140 | for (i = 0; dhcp_options[i].code; i++) {
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141 | if (get_option(packet, dhcp_options[i].code)) {
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142 | num_options++;
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143 | if (dhcp_options[i].code == DHCP_SUBNET)
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144 | num_options++; /* for mton */
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145 | }
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146 | }
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147 | if (packet->siaddr)
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148 | num_options++;
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149 | temp = get_option(packet, DHCP_OPTION_OVER);
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150 | if (temp)
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151 | over = *temp;
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152 | if (!(over & FILE_FIELD) && packet->file[0])
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153 | num_options++;
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154 | if (!(over & SNAME_FIELD) && packet->sname[0])
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155 | num_options++;
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156 | }
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157 |
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158 | envp = xzalloc(sizeof(char *) * (num_options + 5));
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159 | j = 0;
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160 | envp[j++] = xasprintf("interface=%s", client_config.interface);
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161 | var = getenv("PATH");
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162 | if (var)
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163 | envp[j++] = xasprintf("PATH=%s", var);
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164 | var = getenv("HOME");
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165 | if (var)
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166 | envp[j++] = xasprintf("HOME=%s", var);
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167 |
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168 | if (packet == NULL)
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169 | return envp;
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170 |
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171 | envp[j] = xmalloc(sizeof("ip=255.255.255.255"));
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172 | sprintip(envp[j++], "ip=", (uint8_t *) &packet->yiaddr);
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173 |
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174 | for (i = 0; dhcp_options[i].code; i++) {
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175 | temp = get_option(packet, dhcp_options[i].code);
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176 | if (!temp)
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177 | continue;
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178 | envp[j++] = alloc_fill_opts(temp, &dhcp_options[i]);
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179 |
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180 | /* Fill in a subnet bits option for things like /24 */
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181 | if (dhcp_options[i].code == DHCP_SUBNET) {
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182 | memcpy(&subnet, temp, 4);
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183 | envp[j++] = xasprintf("mask=%d", mton(&subnet));
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184 | }
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185 | }
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186 | if (packet->siaddr) {
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187 | envp[j] = xmalloc(sizeof("siaddr=255.255.255.255"));
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188 | sprintip(envp[j++], "siaddr=", (uint8_t *) &packet->siaddr);
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189 | }
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190 | if (!(over & FILE_FIELD) && packet->file[0]) {
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191 | /* watch out for invalid packets */
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192 | packet->file[sizeof(packet->file) - 1] = '\0';
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193 | envp[j++] = xasprintf("boot_file=%s", packet->file);
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194 | }
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195 | if (!(over & SNAME_FIELD) && packet->sname[0]) {
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196 | /* watch out for invalid packets */
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197 | packet->sname[sizeof(packet->sname) - 1] = '\0';
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198 | envp[j++] = xasprintf("sname=%s", packet->sname);
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199 | }
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200 | return envp;
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201 | }
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202 |
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203 |
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204 | /* Call a script with a par file and env vars */
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205 | void udhcp_run_script(struct dhcpMessage *packet, const char *name)
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206 | {
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207 | int pid;
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208 | char **envp, **curr;
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209 |
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210 | if (client_config.script == NULL)
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211 | return;
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212 |
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213 | DEBUG("vfork'ing and execle'ing %s", client_config.script);
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214 |
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215 | envp = fill_envp(packet);
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216 |
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217 | /* call script */
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218 | // can we use wait4pid(spawn(...)) here?
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219 | pid = vfork();
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220 | if (pid < 0) return;
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221 | if (pid == 0) {
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222 | /* close fd's? */
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223 | /* exec script */
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224 | execle(client_config.script, client_config.script,
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225 | name, NULL, envp);
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226 | bb_perror_msg_and_die("script %s failed", client_config.script);
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227 | }
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228 | waitpid(pid, NULL, 0);
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229 | for (curr = envp; *curr; curr++)
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230 | free(*curr);
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231 | free(envp);
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232 | }
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