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#define _GNU_SOURCE
#include <errno.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <ifaddrs.h>
#include <syscall.h>
#include <net/if.h>
#include <netinet/in.h>
#include "netlink.h"
#define IFADDRS_HASH_SIZE 64
/* getifaddrs() reports hardware addresses with PF_PACKET that implies
* struct sockaddr_ll. But e.g. Infiniband socket address length is
* longer than sockaddr_ll.ssl_addr[8] can hold. Use this hack struct
* to extend ssl_addr - callers should be able to still use it. */
struct sockaddr_ll_hack {
unsigned short sll_family, sll_protocol;
int sll_ifindex;
unsigned short sll_hatype;
unsigned char sll_pkttype, sll_halen;
unsigned char sll_addr[24];
};
union sockany {
struct sockaddr sa;
struct sockaddr_ll_hack ll;
struct sockaddr_in v4;
struct sockaddr_in6 v6;
};
struct ifaddrs_storage {
struct ifaddrs ifa;
struct ifaddrs_storage *hash_next;
union sockany addr, netmask, ifu;
unsigned int index;
char name[IFNAMSIZ+1];
};
struct ifaddrs_ctx {
struct ifaddrs_storage *first;
struct ifaddrs_storage *last;
struct ifaddrs_storage *hash[IFADDRS_HASH_SIZE];
};
void freeifaddrs(struct ifaddrs *ifp)
{
struct ifaddrs *n;
while (ifp) {
n = ifp->ifa_next;
free(ifp);
ifp = n;
}
}
static void copy_addr(struct sockaddr **r, int af, union sockany *sa, void *addr, size_t addrlen, int ifindex)
{
uint8_t *dst;
int len;
switch (af) {
case AF_INET:
dst = (uint8_t*) &sa->v4.sin_addr;
len = 4;
break;
case AF_INET6:
dst = (uint8_t*) &sa->v6.sin6_addr;
len = 16;
if (IN6_IS_ADDR_LINKLOCAL(addr) || IN6_IS_ADDR_MC_LINKLOCAL(addr))
sa->v6.sin6_scope_id = ifindex;
break;
default:
return;
}
if (addrlen < len) return;
sa->sa.sa_family = af;
memcpy(dst, addr, len);
*r = &sa->sa;
}
static void gen_netmask(struct sockaddr **r, int af, union sockany *sa, int prefixlen)
{
uint8_t addr[16] = {0};
int i;
if (prefixlen > 8*sizeof(addr)) prefixlen = 8*sizeof(addr);
i = prefixlen / 8;
memset(addr, 0xff, i);
if (i < sizeof(addr)) addr[i++] = 0xff << (8 - (prefixlen % 8));
copy_addr(r, af, sa, addr, sizeof(addr), 0);
}
static void copy_lladdr(struct sockaddr **r, union sockany *sa, void *addr, size_t addrlen, int ifindex, unsigned short hatype)
{
if (addrlen > sizeof(sa->ll.sll_addr)) return;
sa->ll.sll_family = AF_PACKET;
sa->ll.sll_ifindex = ifindex;
sa->ll.sll_hatype = hatype;
sa->ll.sll_halen = addrlen;
memcpy(sa->ll.sll_addr, addr, addrlen);
*r = &sa->sa;
}
static int netlink_msg_to_ifaddr(void *pctx, struct nlmsghdr *h)
{
struct ifaddrs_ctx *ctx = pctx;
struct ifaddrs_storage *ifs, *ifs0;
struct ifinfomsg *ifi = NLMSG_DATA(h);
struct ifaddrmsg *ifa = NLMSG_DATA(h);
struct rtattr *rta;
int stats_len = 0;
if (h->nlmsg_type == RTM_NEWLINK) {
for (rta = NLMSG_RTA(h, sizeof(*ifi)); NLMSG_RTAOK(rta, h); rta = RTA_NEXT(rta)) {
if (rta->rta_type != IFLA_STATS) continue;
stats_len = RTA_DATALEN(rta);
break;
}
} else {
for (ifs0 = ctx->hash[ifa->ifa_index % IFADDRS_HASH_SIZE]; ifs0; ifs0 = ifs0->hash_next)
if (ifs0->index == ifa->ifa_index)
break;
if (!ifs0) return 0;
}
ifs = calloc(1, sizeof(struct ifaddrs_storage) + stats_len);
if (ifs == 0) return -1;
if (h->nlmsg_type == RTM_NEWLINK) {
ifs->index = ifi->ifi_index;
ifs->ifa.ifa_flags = ifi->ifi_flags;
for (rta = NLMSG_RTA(h, sizeof(*ifi)); NLMSG_RTAOK(rta, h); rta = RTA_NEXT(rta)) {
switch (rta->rta_type) {
case IFLA_IFNAME:
if (RTA_DATALEN(rta) < sizeof(ifs->name)) {
memcpy(ifs->name, RTA_DATA(rta), RTA_DATALEN(rta));
ifs->ifa.ifa_name = ifs->name;
}
break;
case IFLA_ADDRESS:
copy_lladdr(&ifs->ifa.ifa_addr, &ifs->addr, RTA_DATA(rta), RTA_DATALEN(rta), ifi->ifi_index, ifi->ifi_type);
break;
case IFLA_BROADCAST:
copy_lladdr(&ifs->ifa.ifa_broadaddr, &ifs->ifu, RTA_DATA(rta), RTA_DATALEN(rta), ifi->ifi_index, ifi->ifi_type);
break;
case IFLA_STATS:
ifs->ifa.ifa_data = (void*)(ifs+1);
memcpy(ifs->ifa.ifa_data, RTA_DATA(rta), RTA_DATALEN(rta));
break;
}
}
if (ifs->ifa.ifa_name) {
unsigned int bucket = ifs->index % IFADDRS_HASH_SIZE;
ifs->hash_next = ctx->hash[bucket];
ctx->hash[bucket] = ifs;
}
} else {
ifs->ifa.ifa_name = ifs0->ifa.ifa_name;
ifs->ifa.ifa_flags = ifs0->ifa.ifa_flags;
for (rta = NLMSG_RTA(h, sizeof(*ifa)); NLMSG_RTAOK(rta, h); rta = RTA_NEXT(rta)) {
switch (rta->rta_type) {
case IFA_ADDRESS:
copy_addr(&ifs->ifa.ifa_addr, ifa->ifa_family, &ifs->addr, RTA_DATA(rta), RTA_DATALEN(rta), ifa->ifa_index);
break;
case IFA_BROADCAST:
/* For point-to-point links this is peer, but ifa_broadaddr
* and ifa_dstaddr are union, so this works for both. */
copy_addr(&ifs->ifa.ifa_broadaddr, ifa->ifa_family, &ifs->ifu, RTA_DATA(rta), RTA_DATALEN(rta), ifa->ifa_index);
break;
case IFA_LABEL:
if (RTA_DATALEN(rta) < sizeof(ifs->name)) {
memcpy(ifs->name, RTA_DATA(rta), RTA_DATALEN(rta));
ifs->ifa.ifa_name = ifs->name;
}
break;
}
}
if (ifs->ifa.ifa_addr)
gen_netmask(&ifs->ifa.ifa_netmask, ifa->ifa_family, &ifs->netmask, ifa->ifa_prefixlen);
}
if (ifs->ifa.ifa_name) {
if (!ctx->first) ctx->first = ifs;
if (ctx->last) ctx->last->ifa.ifa_next = &ifs->ifa;
ctx->last = ifs;
} else {
free(ifs);
}
return 0;
}
int getifaddrs(struct ifaddrs **ifap)
{
struct ifaddrs_ctx _ctx, *ctx = &_ctx;
int r;
memset(ctx, 0, sizeof *ctx);
r = __rtnetlink_enumerate(AF_UNSPEC, AF_UNSPEC, netlink_msg_to_ifaddr, ctx);
if (r == 0) *ifap = &ctx->first->ifa;
else freeifaddrs(&ctx->first->ifa);
return r;
}
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