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/* (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>
static struct ifaddrs* list_add(struct ifaddrs** list, struct ifaddrs** head, char* ifname)
{
struct ifaddrs* curr = calloc(1, sizeof(struct ifaddrs));
if(curr) {
curr->ifa_name = strdup(ifname);
if(!curr->ifa_name) {
free(curr);
curr = 0;
goto out;
}
if(*head) (*head)->ifa_next = curr;
*head = curr;
if(!*list) *list = curr;
}
out:
return curr;
}
void freeifaddrs(struct ifaddrs *ifp)
{
struct ifaddrs *head = ifp;
while(head) {
free(head->ifa_name);
free(head->ifa_addr);
free(head->ifa_netmask);
free(head->ifa_ifu.ifu_dstaddr);
free(head->ifa_data);
void *p = head;
head = head->ifa_next;
free(p);
}
}
static struct sockaddr *sockaddr_in_dup(struct sockaddr_in *src)
{
struct sockaddr_in *nu = malloc(sizeof(struct sockaddr_in));
if(nu) *nu = *src;
return (struct sockaddr*) nu;
}
static struct sockaddr *sockaddr_in6_dup(struct sockaddr_in6 *src)
{
struct sockaddr_in6 *nu = malloc(sizeof(struct sockaddr_in6));
if(nu) *nu = *src;
return (struct sockaddr*) nu;
}
static void ipv6netmask(unsigned prefix_length, struct sockaddr_in6 *sa)
{
// FIXME: left for bit-wizard rich
memset(&sa->sin6_addr, -1, sizeof(sa->sin6_addr));
}
static void dealwithipv6(struct ifaddrs **list, struct ifaddrs** head)
{
FILE* f = fopen("/proc/net/if_inet6", "r");
/* 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;
struct ifaddrs* curr = list_add(list, head, name);
if(!curr) goto out;
curr->ifa_addr = sockaddr_in6_dup(&sa);
ipv6netmask(c, &sa);
curr->ifa_netmask = sockaddr_in6_dup(&sa);
/* find ipv4 struct with the same interface name to copy flags */
struct ifaddrs* scan = *list;
for(;scan && strcmp(name, scan->ifa_name);scan=scan->ifa_next);
if(scan) curr->ifa_flags=scan->ifa_flags;
else curr->ifa_flags = 0;
} else errno = 0;
}
}
out:
fclose(f);
}
int getifaddrs(struct ifaddrs **ifap)
{
FILE* f = fopen("/proc/net/dev", "r");
/* the alternative to parsing /proc.. seems to be iterating
through the interfaces using an index number in ifreq.ifr_ifindex
until we get some error code back. the kernel will fill ifr_name field
for valid ifindices (SIOCGIFINDEX) */
if(!f) return -1;
struct ifaddrs *list = 0, *head = 0;
char* line; char linebuf[512];
while((line = fgets(linebuf, sizeof linebuf, f))) {
while(isspace(*line) && *line) line++;
char* start = line;
while(*line && isalnum(*line)) line++;
if(line > start && *line == ':') {
// found interface
*line = 0;
struct ifaddrs* curr = list_add(&list, &head, start);
if(!curr) {
fclose(f);
goto err2;
}
}
}
fclose(f);
int sock = socket(PF_INET, SOCK_DGRAM, 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;
else {
size_t reqitems = conf.ifc_len / sizeof(struct ifreq);
for(head = list; head; head=head->ifa_next) {
size_t i;
for(i = 0; i < reqitems; i++) {
// get SIOCGIFADDR of active interfaces.
if(!strcmp(reqs[i].ifr_name, head->ifa_name)) {
head->ifa_addr = sockaddr_in_dup((struct sockaddr_in*) &reqs[i].ifr_addr);
break;
}
}
struct ifreq req;
snprintf(req.ifr_name, sizeof req.ifr_name, "%s", head->ifa_name);
if(-1 == ioctl(sock, SIOCGIFFLAGS, &req)) goto err;
head->ifa_flags = req.ifr_flags;
if(head->ifa_addr) {
/* or'ing flags with IFF_LOWER_UP on active interfaces to mimic glibc */
head->ifa_flags |= IFF_LOWER_UP;
if(-1 == ioctl(sock, SIOCGIFNETMASK, &req)) goto err;
head->ifa_netmask = sockaddr_in_dup((struct sockaddr_in*) &req.ifr_netmask);
if(head->ifa_flags & IFF_POINTOPOINT) {
if(-1 == ioctl(sock, SIOCGIFDSTADDR, &req)) goto err;
head->ifa_ifu.ifu_dstaddr = sockaddr_in_dup((struct sockaddr_in*) &req.ifr_dstaddr);
} else {
if(-1 == ioctl(sock, SIOCGIFBRDADDR, &req)) goto err;
head->ifa_ifu.ifu_broadaddr = sockaddr_in_dup((struct sockaddr_in*) &req.ifr_broadaddr);
}
}
}
}
close(sock);
void* last = 0;
for(head = list; head; head=head->ifa_next) last=head;
head = last;
dealwithipv6(&list, &head);
*ifap = list;
return 0;
err:
close(sock);
err2:
freeifaddrs(list);
return -1;
}
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