#include <sys/socket.h>

#include <sys/un.h>

#include <asm/types.h>

#include <inttypes.h>

#include <linux/netlink.h>

#include <linux/rtnetlink.h>

#include <string.h>

#include <assert.h>

#include <errno.h>

#include <limits.h>

#include <arpa/inet.h>

#include <unistd.h>

#include <inttypes.h>

#include <stdlib.h>

#include "netlink.h"

static int address_compare(const void *_a, const void *_b) {

const struct address *a = _a, *b = _b;

/* Order lowest scope first, IPv4 before IPv6, lowest interface index first */

if (a->scope < b->scope)

return -1;

if (a->scope > b->scope)

return 1;

if (a->family == AF_INET && b->family == AF_INET6)

return -1;

if (a->family == AF_INET6 && b->family == AF_INET)

return 1;

if (a->ifindex < b->ifindex)

return -1;

if (a->ifindex > b->ifindex)

return 1;

return 0;

}

int netlink_acquire_addresses(struct address **_list, unsigned *_n_list) {

struct {

struct nlmsghdr hdr;

struct rtgenmsg gen;

} req;

struct rtgenmsg *gen;

int fd, r, on = 1;

uint32_t seq = 4711;

struct address *list = NULL;

unsigned n_list = 0;

fd = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE);

if (fd < 0)

return -errno;

if (setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on)) < 0) {

r = -errno;

goto finish;

}

memset(&req, 0, sizeof(req));

req.hdr.nlmsg_len = NLMSG_LENGTH(sizeof(struct rtgenmsg));

req.hdr.nlmsg_type = RTM_GETADDR;

req.hdr.nlmsg_flags = NLM_F_REQUEST|NLM_F_DUMP|NLM_F_ACK;

req.hdr.nlmsg_seq = seq;

req.hdr.nlmsg_pid = 0;

gen = NLMSG_DATA(&req.hdr);

gen->rtgen_family = AF_UNSPEC;

if (send(fd, &req, req.hdr.nlmsg_len, 0) < 0) {

r = -errno;

goto finish;

}

for (;;) {

ssize_t bytes;

struct msghdr msg;

struct cmsghdr *cmsg;

struct ucred *ucred;

struct iovec iov;

struct nlmsghdr *p;

uint8_t cred_buffer[CMSG_SPACE(sizeof(struct ucred))];

struct {

struct nlmsghdr hdr;

struct ifaddrmsg ifaddrmsg;

uint8_t payload[16*1024];

} resp;

memset(&iov, 0, sizeof(iov));

iov.iov_base = &resp;

iov.iov_len = sizeof(resp);

memset(&msg, 0, sizeof(msg));

msg.msg_name = NULL;

msg.msg_namelen = 0;

msg.msg_iov = &iov;

msg.msg_iovlen = 1;

msg.msg_control = cred_buffer;

msg.msg_controllen = sizeof(cred_buffer);

msg.msg_flags = 0;

bytes = recvmsg(fd, &msg, 0);

if (bytes < 0) {

r = -errno;

goto finish;

}

cmsg = CMSG_FIRSTHDR(&msg);

if (!cmsg || cmsg->cmsg_type != SCM_CREDENTIALS) {

r = -EIO;

goto finish;

}

ucred = (struct ucred*) CMSG_DATA(cmsg);

if (ucred->uid != 0 || ucred->pid != 0)

continue;

for (p = &resp.hdr; bytes > 0; p = NLMSG_NEXT(p, bytes)) {

struct ifaddrmsg *ifaddrmsg;

struct rtattr *a;

size_t l;

void *local = NULL, *address = NULL;

if (!NLMSG_OK(p, (size_t) bytes)) {

r = -EIO;

goto finish;

}

if (p->nlmsg_seq != seq)

continue;

if (p->nlmsg_type == NLMSG_DONE) {

r = 0;

goto finish;

}

if (p->nlmsg_type == NLMSG_ERROR) {

struct nlmsgerr *nlmsgerr;

nlmsgerr = NLMSG_DATA(p);

r = -nlmsgerr->error;

goto finish;

}

if (p->nlmsg_type != RTM_NEWADDR)

continue;

ifaddrmsg = NLMSG_DATA(p);

if (ifaddrmsg->ifa_family != AF_INET &&

ifaddrmsg->ifa_family != AF_INET6)

continue;

if (ifaddrmsg->ifa_scope == RT_SCOPE_HOST ||

ifaddrmsg->ifa_scope == RT_SCOPE_NOWHERE)

continue;

if (ifaddrmsg->ifa_flags & IFA_F_DEPRECATED)

continue;

l = NLMSG_PAYLOAD(p, sizeof(struct ifaddrmsg));

a = IFA_RTA(ifaddrmsg);

while (RTA_OK(a, l)) {

if (a->rta_type == IFA_ADDRESS)

address = RTA_DATA(a);

else if (a->rta_type == IFA_LOCAL)

local = RTA_DATA(a);

a = RTA_NEXT(a, l);

}

if (local)

address = local;

if (!address)

continue;

list = realloc(list, (n_list+1) * sizeof(struct address));

if (!list) {

r = -ENOMEM;

goto finish;

}

list[n_list].family = ifaddrmsg->ifa_family;

list[n_list].scope = ifaddrmsg->ifa_scope;

memcpy(list[n_list].address, address, ifaddrmsg->ifa_family == AF_INET ? 4 : 16);

list[n_list].ifindex = ifaddrmsg->ifa_index;

n_list++;

}

}

finish:

close(fd);

if (r < 0)

free(list);

else {

qsort(list, n_list, sizeof(struct address), address_compare);

*_list = list;

*_n_list = n_list;

}

return r;

}