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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 | /* (C) 2013 John Spencer. released under musl's standard MIT license. */
#undef _GNU_SOURCE
#define _GNU_SOURCE
#include <ifaddrs.h>
#include <stdlib.h>
#include <net/if.h> /* IFNAMSIZ, ifreq, ifconf */
#include <stdio.h>
#include <ctype.h>
#include <string.h>
#include <errno.h>
#include <arpa/inet.h> /* inet_pton */
#include <unistd.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
typedef union {
struct sockaddr_in6 v6;
struct sockaddr_in v4;
} soa;
typedef struct ifaddrs_storage {
struct ifaddrs ifa;
soa addr;
soa netmask;
soa dst;
char name[IFNAMSIZ+1];
} stor;
#define next ifa.ifa_next
static stor* list_add(stor** list, stor** head, char* ifname)
{
stor* curr = calloc(1, sizeof(stor));
if(curr) {
strcpy(curr->name, ifname);
curr->ifa.ifa_name = curr->name;
if(*head) (*head)->next = (struct ifaddrs*) curr;
*head = curr;
if(!*list) *list = curr;
}
return curr;
}
void freeifaddrs(struct ifaddrs *ifp)
{
stor *head = (stor *) ifp;
while(head) {
void *p = head;
head = (stor *) head->next;
free(p);
}
}
static void ipv6netmask(unsigned prefix_length, struct sockaddr_in6 *sa)
{
unsigned char* hb = sa->sin6_addr.s6_addr;
unsigned onebytes = prefix_length / 8;
unsigned bits = prefix_length % 8;
unsigned nullbytes = 16 - onebytes;
memset(hb, -1, onebytes);
memset(hb+onebytes, 0, nullbytes);
if(bits) {
unsigned char x = -1;
x <<= 8 - bits;
hb[onebytes] = x;
}
}
static void dealwithipv6(stor **list, stor** head)
{
FILE* f = fopen("/proc/net/if_inet6", "rbe");
/* 00000000000000000000000000000001 01 80 10 80 lo
A B C D E F
all numbers in hex
A = addr B=netlink device#, C=prefix length,
D = scope value (ipv6.h) E = interface flags (rnetlink.h, addrconf.c)
F = if name */
char v6conv[32 + 7 + 1], *v6;
char *line, linebuf[512];
if(!f) return;
while((line = fgets(linebuf, sizeof linebuf, f))) {
v6 = v6conv;
size_t i = 0;
for(; i < 8; i++) {
memcpy(v6, line, 4);
v6+=4;
*v6++=':';
line+=4;
}
--v6; *v6 = 0;
line++;
unsigned b, c, d, e;
char name[IFNAMSIZ+1];
if(5 == sscanf(line, "%x %x %x %x %s", &b, &c, &d, &e, name)) {
struct sockaddr_in6 sa = {0};
if(1 == inet_pton(AF_INET6, v6conv, &sa.sin6_addr)) {
sa.sin6_family = AF_INET6;
stor* curr = list_add(list, head, name);
if(!curr) goto out;
curr->addr.v6 = sa;
curr->ifa.ifa_addr = (struct sockaddr*) &curr->addr;
ipv6netmask(c, &sa);
curr->netmask.v6 = sa;
curr->ifa.ifa_netmask = (struct sockaddr*) &curr->netmask;
/* find ipv4 struct with the same interface name to copy flags */
stor* scan = *list;
for(;scan && strcmp(name, scan->name);scan=(stor*)scan->next);
if(scan) curr->ifa.ifa_flags = scan->ifa.ifa_flags;
else curr->ifa.ifa_flags = 0;
} else errno = 0;
}
}
out:
fclose(f);
}
int getifaddrs(struct ifaddrs **ifap)
{
stor *list = 0, *head = 0;
struct if_nameindex* ii = if_nameindex();
if(!ii) return -1;
size_t i;
for(i = 0; ii[i].if_index || ii[i].if_name; i++) {
stor* curr = list_add(&list, &head, ii[i].if_name);
if(!curr) {
if_freenameindex(ii);
goto err2;
}
}
if_freenameindex(ii);
int sock = socket(PF_INET, SOCK_DGRAM|SOCK_CLOEXEC, IPPROTO_IP);
if(sock == -1) goto err2;
struct ifreq reqs[32]; /* arbitrary chosen boundary */
struct ifconf conf = {.ifc_len = sizeof reqs, .ifc_req = reqs};
if(-1 == ioctl(sock, SIOCGIFCONF, &conf)) goto err;
size_t reqitems = conf.ifc_len / sizeof(struct ifreq);
for(head = list; head; head = (stor*)head->next) {
for(i = 0; i < reqitems; i++) {
// get SIOCGIFADDR of active interfaces.
if(!strcmp(reqs[i].ifr_name, head->name)) {
head->addr.v4 = *(struct sockaddr_in*)&reqs[i].ifr_addr;
head->ifa.ifa_addr = (struct sockaddr*) &head->addr;
break;
}
}
struct ifreq req;
snprintf(req.ifr_name, sizeof req.ifr_name, "%s", head->name);
if(-1 == ioctl(sock, SIOCGIFFLAGS, &req)) goto err;
head->ifa.ifa_flags = req.ifr_flags;
if(head->ifa.ifa_addr) {
/* or'ing flags with IFF_LOWER_UP on active interfaces to mimic glibc */
head->ifa.ifa_flags |= IFF_LOWER_UP;
if(-1 == ioctl(sock, SIOCGIFNETMASK, &req)) goto err;
head->netmask.v4 = *(struct sockaddr_in*)&req.ifr_netmask;
head->ifa.ifa_netmask = (struct sockaddr*) &head->netmask;
if(head->ifa.ifa_flags & IFF_POINTOPOINT) {
if(-1 == ioctl(sock, SIOCGIFDSTADDR, &req)) goto err;
head->dst.v4 = *(struct sockaddr_in*)&req.ifr_dstaddr;
} else {
if(-1 == ioctl(sock, SIOCGIFBRDADDR, &req)) goto err;
head->dst.v4 = *(struct sockaddr_in*)&req.ifr_broadaddr;
}
head->ifa.ifa_ifu.ifu_dstaddr = (struct sockaddr*) &head->dst;
}
}
close(sock);
void* last = 0;
for(head = list; head; head=(stor*)head->next) last=head;
head = last;
dealwithipv6(&list, &head);
*ifap = (struct ifaddrs*) list;
return 0;
err:
close(sock);
err2:
freeifaddrs((struct ifaddrs*) list);
return -1;
}
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