1 | #define _GNU_SOURCE
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2 | #include <errno.h>
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3 | #include <string.h>
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4 | #include <stdlib.h>
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5 | #include <unistd.h>
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6 | #include <ifaddrs.h>
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7 | #include <syscall.h>
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8 | #include <net/if.h>
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9 | #include <netinet/in.h>
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10 | #include "netlink.h"
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11 |
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12 | #define IFADDRS_HASH_SIZE 64
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13 |
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14 | /* getifaddrs() reports hardware addresses with PF_PACKET that implies
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15 | * struct sockaddr_ll. But e.g. Infiniband socket address length is
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16 | * longer than sockaddr_ll.ssl_addr[8] can hold. Use this hack struct
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17 | * to extend ssl_addr - callers should be able to still use it. */
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18 | struct sockaddr_ll_hack {
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19 | unsigned short sll_family, sll_protocol;
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20 | int sll_ifindex;
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21 | unsigned short sll_hatype;
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22 | unsigned char sll_pkttype, sll_halen;
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23 | unsigned char sll_addr[24];
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24 | };
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25 |
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26 | union sockany {
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27 | struct sockaddr sa;
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28 | struct sockaddr_ll_hack ll;
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29 | struct sockaddr_in v4;
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30 | struct sockaddr_in6 v6;
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31 | };
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32 |
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33 | struct ifaddrs_storage {
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34 | struct ifaddrs ifa;
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35 | struct ifaddrs_storage *hash_next;
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36 | union sockany addr, netmask, ifu;
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37 | unsigned int index;
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38 | char name[IFNAMSIZ+1];
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39 | };
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40 |
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41 | struct ifaddrs_ctx {
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42 | struct ifaddrs_storage *first;
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43 | struct ifaddrs_storage *last;
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44 | struct ifaddrs_storage *hash[IFADDRS_HASH_SIZE];
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45 | };
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46 |
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47 | void freeifaddrs(struct ifaddrs *ifp)
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48 | {
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49 | struct ifaddrs *n;
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50 | while (ifp) {
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51 | n = ifp->ifa_next;
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52 | free(ifp);
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53 | ifp = n;
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54 | }
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55 | }
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56 |
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57 | static void copy_addr(struct sockaddr **r, int af, union sockany *sa, void *addr, size_t addrlen, int ifindex)
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58 | {
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59 | uint8_t *dst;
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60 | int len;
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61 |
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62 | switch (af) {
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63 | case AF_INET:
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64 | dst = (uint8_t*) &sa->v4.sin_addr;
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65 | len = 4;
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66 | break;
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67 | case AF_INET6:
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68 | dst = (uint8_t*) &sa->v6.sin6_addr;
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69 | len = 16;
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70 | if (IN6_IS_ADDR_LINKLOCAL(addr) || IN6_IS_ADDR_MC_LINKLOCAL(addr))
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71 | sa->v6.sin6_scope_id = ifindex;
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72 | break;
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73 | default:
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74 | return;
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75 | }
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76 | if (addrlen < len) return;
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77 | sa->sa.sa_family = af;
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78 | memcpy(dst, addr, len);
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79 | *r = &sa->sa;
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80 | }
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81 |
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82 | static void gen_netmask(struct sockaddr **r, int af, union sockany *sa, int prefixlen)
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83 | {
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84 | uint8_t addr[16] = {0};
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85 | int i;
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86 |
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87 | if (prefixlen > 8*sizeof(addr)) prefixlen = 8*sizeof(addr);
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88 | i = prefixlen / 8;
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89 | memset(addr, 0xff, i);
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90 | if (i < sizeof(addr)) addr[i++] = 0xff << (8 - (prefixlen % 8));
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91 | copy_addr(r, af, sa, addr, sizeof(addr), 0);
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92 | }
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93 |
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94 | static void copy_lladdr(struct sockaddr **r, union sockany *sa, void *addr, size_t addrlen, int ifindex, unsigned short hatype)
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95 | {
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96 | if (addrlen > sizeof(sa->ll.sll_addr)) return;
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97 | sa->ll.sll_family = AF_PACKET;
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98 | sa->ll.sll_ifindex = ifindex;
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99 | sa->ll.sll_hatype = hatype;
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100 | sa->ll.sll_halen = addrlen;
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101 | memcpy(sa->ll.sll_addr, addr, addrlen);
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102 | *r = &sa->sa;
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103 | }
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104 |
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105 | static int netlink_msg_to_ifaddr(void *pctx, struct nlmsghdr *h)
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106 | {
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107 | struct ifaddrs_ctx *ctx = pctx;
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108 | struct ifaddrs_storage *ifs, *ifs0;
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109 | struct ifinfomsg *ifi = NLMSG_DATA(h);
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110 | struct ifaddrmsg *ifa = NLMSG_DATA(h);
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111 | struct rtattr *rta;
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112 | int stats_len = 0;
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113 |
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114 | if (h->nlmsg_type == RTM_NEWLINK) {
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115 | for (rta = NLMSG_RTA(h, sizeof(*ifi)); NLMSG_RTAOK(rta, h); rta = RTA_NEXT(rta)) {
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116 | if (rta->rta_type != IFLA_STATS) continue;
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117 | stats_len = RTA_DATALEN(rta);
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118 | break;
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119 | }
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120 | } else {
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121 | for (ifs0 = ctx->hash[ifa->ifa_index % IFADDRS_HASH_SIZE]; ifs0; ifs0 = ifs0->hash_next)
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122 | if (ifs0->index == ifa->ifa_index)
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123 | break;
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124 | if (!ifs0) return 0;
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125 | }
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126 |
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127 | ifs = calloc(1, sizeof(struct ifaddrs_storage) + stats_len);
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128 | if (ifs == 0) return -1;
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129 |
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130 | if (h->nlmsg_type == RTM_NEWLINK) {
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131 | ifs->index = ifi->ifi_index;
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132 | ifs->ifa.ifa_flags = ifi->ifi_flags;
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133 |
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134 | for (rta = NLMSG_RTA(h, sizeof(*ifi)); NLMSG_RTAOK(rta, h); rta = RTA_NEXT(rta)) {
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135 | switch (rta->rta_type) {
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136 | case IFLA_IFNAME:
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137 | if (RTA_DATALEN(rta) < sizeof(ifs->name)) {
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138 | memcpy(ifs->name, RTA_DATA(rta), RTA_DATALEN(rta));
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139 | ifs->ifa.ifa_name = ifs->name;
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140 | }
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141 | break;
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142 | case IFLA_ADDRESS:
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143 | copy_lladdr(&ifs->ifa.ifa_addr, &ifs->addr, RTA_DATA(rta), RTA_DATALEN(rta), ifi->ifi_index, ifi->ifi_type);
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144 | break;
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145 | case IFLA_BROADCAST:
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146 | copy_lladdr(&ifs->ifa.ifa_broadaddr, &ifs->ifu, RTA_DATA(rta), RTA_DATALEN(rta), ifi->ifi_index, ifi->ifi_type);
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147 | break;
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148 | case IFLA_STATS:
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149 | ifs->ifa.ifa_data = (void*)(ifs+1);
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150 | memcpy(ifs->ifa.ifa_data, RTA_DATA(rta), RTA_DATALEN(rta));
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151 | break;
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152 | }
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153 | }
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154 | if (ifs->ifa.ifa_name) {
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155 | unsigned int bucket = ifs->index % IFADDRS_HASH_SIZE;
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156 | ifs->hash_next = ctx->hash[bucket];
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157 | ctx->hash[bucket] = ifs;
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158 | }
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159 | } else {
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160 | ifs->ifa.ifa_name = ifs0->ifa.ifa_name;
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161 | ifs->ifa.ifa_flags = ifs0->ifa.ifa_flags;
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162 | for (rta = NLMSG_RTA(h, sizeof(*ifa)); NLMSG_RTAOK(rta, h); rta = RTA_NEXT(rta)) {
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163 | switch (rta->rta_type) {
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164 | case IFA_ADDRESS:
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165 | /* If ifa_addr is already set we, received an IFA_LOCAL before
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166 | * so treat this as destination address */
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167 | if (ifs->ifa.ifa_addr)
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168 | copy_addr(&ifs->ifa.ifa_dstaddr, ifa->ifa_family, &ifs->ifu, RTA_DATA(rta), RTA_DATALEN(rta), ifa->ifa_index);
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169 | else
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170 | copy_addr(&ifs->ifa.ifa_addr, ifa->ifa_family, &ifs->addr, RTA_DATA(rta), RTA_DATALEN(rta), ifa->ifa_index);
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171 | break;
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172 | case IFA_BROADCAST:
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173 | copy_addr(&ifs->ifa.ifa_broadaddr, ifa->ifa_family, &ifs->ifu, RTA_DATA(rta), RTA_DATALEN(rta), ifa->ifa_index);
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174 | break;
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175 | case IFA_LOCAL:
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176 | /* If ifa_addr is set and we get IFA_LOCAL, assume we have
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177 | * a point-to-point network. Move address to correct field. */
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178 | if (ifs->ifa.ifa_addr) {
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179 | ifs->ifu = ifs->addr;
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180 | ifs->ifa.ifa_dstaddr = &ifs->ifu.sa;
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181 | memset(&ifs->addr, 0, sizeof(ifs->addr));
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182 | }
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183 | copy_addr(&ifs->ifa.ifa_addr, ifa->ifa_family, &ifs->addr, RTA_DATA(rta), RTA_DATALEN(rta), ifa->ifa_index);
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184 | break;
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185 | case IFA_LABEL:
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186 | if (RTA_DATALEN(rta) < sizeof(ifs->name)) {
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187 | memcpy(ifs->name, RTA_DATA(rta), RTA_DATALEN(rta));
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188 | ifs->ifa.ifa_name = ifs->name;
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189 | }
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190 | break;
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191 | }
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192 | }
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193 | if (ifs->ifa.ifa_addr)
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194 | gen_netmask(&ifs->ifa.ifa_netmask, ifa->ifa_family, &ifs->netmask, ifa->ifa_prefixlen);
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195 | }
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196 |
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197 | if (ifs->ifa.ifa_name) {
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198 | if (!ctx->first) ctx->first = ifs;
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199 | if (ctx->last) ctx->last->ifa.ifa_next = &ifs->ifa;
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200 | ctx->last = ifs;
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201 | } else {
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202 | free(ifs);
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203 | }
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204 | return 0;
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205 | }
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206 |
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207 | int getifaddrs(struct ifaddrs **ifap)
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208 | {
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209 | struct ifaddrs_ctx _ctx, *ctx = &_ctx;
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210 | int r;
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211 | memset(ctx, 0, sizeof *ctx);
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212 | r = __rtnetlink_enumerate(AF_UNSPEC, AF_UNSPEC, netlink_msg_to_ifaddr, ctx);
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213 | if (r == 0) *ifap = &ctx->first->ifa;
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214 | else freeifaddrs(&ctx->first->ifa);
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215 | return r;
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216 | }
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