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/*
* Copyright (c) 2017, Arnon Yaari
* All rights reserved.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
/*! Based on code from
https://lists.samba.org/archive/samba-technical/2009-February/063079.html
!*/
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <net/if.h>
#include <netinet/in.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/socket.h>
#include "ifaddrs.h"
#define MAX(x,y) ((x)>(y)?(x):(y))
#define SIZE(p) MAX((p).sa_len,sizeof(p))
static struct sockaddr *
sa_dup(struct sockaddr *sa1)
{
struct sockaddr *sa2;
size_t sz = sa1->sa_len;
sa2 = (struct sockaddr *) calloc(1, sz);
if (sa2 == NULL)
return NULL;
memcpy(sa2, sa1, sz);
return sa2;
}
void freeifaddrs(struct ifaddrs *ifp)
{
if (NULL == ifp) return;
free(ifp->ifa_name);
free(ifp->ifa_addr);
free(ifp->ifa_netmask);
free(ifp->ifa_dstaddr);
freeifaddrs(ifp->ifa_next);
free(ifp);
}
int getifaddrs(struct ifaddrs **ifap)
{
int sd, ifsize;
char *ccp, *ecp;
struct ifconf ifc;
struct ifreq *ifr;
struct ifaddrs *cifa = NULL; /* current */
struct ifaddrs *pifa = NULL; /* previous */
const size_t IFREQSZ = sizeof(struct ifreq);
int fam;
*ifap = NULL;
sd = socket(AF_INET, SOCK_DGRAM, 0);
if (sd == -1)
goto error;
/* find how much memory to allocate for the SIOCGIFCONF call */
if (ioctl(sd, SIOCGSIZIFCONF, (caddr_t)&ifsize) < 0)
goto error;
ifc.ifc_req = (struct ifreq *) calloc(1, ifsize);
if (ifc.ifc_req == NULL)
goto error;
ifc.ifc_len = ifsize;
if (ioctl(sd, SIOCGIFCONF, &ifc) < 0)
goto error;
ccp = (char *)ifc.ifc_req;
ecp = ccp + ifsize;
while (ccp < ecp) {
ifr = (struct ifreq *) ccp;
ifsize = sizeof(ifr->ifr_name) + SIZE(ifr->ifr_addr);
fam = ifr->ifr_addr.sa_family;
if (fam == AF_INET || fam == AF_INET6) {
cifa = (struct ifaddrs *) calloc(1, sizeof(struct ifaddrs));
if (cifa == NULL)
goto error;
cifa->ifa_next = NULL;
if (pifa == NULL) *ifap = cifa; /* first one */
else pifa->ifa_next = cifa;
cifa->ifa_name = strdup(ifr->ifr_name);
if (cifa->ifa_name == NULL)
goto error;
cifa->ifa_flags = 0;
cifa->ifa_dstaddr = NULL;
cifa->ifa_addr = sa_dup(&ifr->ifr_addr);
if (cifa->ifa_addr == NULL)
goto error;
if (fam == AF_INET) {
if (ioctl(sd, SIOCGIFNETMASK, ifr, IFREQSZ) < 0)
goto error;
cifa->ifa_netmask = sa_dup(&ifr->ifr_addr);
if (cifa->ifa_netmask == NULL)
goto error;
}
if (0 == ioctl(sd, SIOCGIFFLAGS, ifr)) /* optional */
cifa->ifa_flags = ifr->ifr_flags;
if (fam == AF_INET) {
if (ioctl(sd, SIOCGIFDSTADDR, ifr, IFREQSZ) < 0) {
if (0 == ioctl(sd, SIOCGIFBRDADDR, ifr, IFREQSZ)) {
cifa->ifa_dstaddr = sa_dup(&ifr->ifr_addr);
if (cifa->ifa_dstaddr == NULL)
goto error;
}
}
else {
cifa->ifa_dstaddr = sa_dup(&ifr->ifr_addr);
if (cifa->ifa_dstaddr == NULL)
goto error;
}
}
pifa = cifa;
}
ccp += ifsize;
}
free(ifc.ifc_req);
close(sd);
return 0;
error:
if (ifc.ifc_req != NULL)
free(ifc.ifc_req);
if (sd != -1)
close(sd);
freeifaddrs(*ifap);
return (-1);
}
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