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/* SPDX-License-Identifier: MIT
*
* Copyright (C) 2019 WireGuard LLC. All Rights Reserved.
*/
#include <arpa/inet.h>
#include <libmnl/libmnl.h>
#include <linux/rtnetlink.h>
#include <stdint.h>
#include <time.h>
#include "dbg.h"
#include "common.h"
struct mnl_cb_data {
uint32_t ifindex;
struct wg_combined_ip *ip;
bool ip_found;
bool duplicate;
};
static struct mnl_socket *nl = NULL;
static void iface_update(uint16_t cmd, uint16_t flags, uint32_t ifindex,
const struct wg_combined_ip *addr)
{
char buf[MNL_SOCKET_BUFFER_SIZE];
struct nlmsghdr *nlh;
unsigned int seq, portid;
struct ifaddrmsg *ifaddr; /* linux/if_addr.h */
int ret;
portid = mnl_socket_get_portid(nl);
seq = time(NULL);
nlh = mnl_nlmsg_put_header(buf);
nlh->nlmsg_seq = seq;
nlh->nlmsg_type = cmd;
nlh->nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK | flags;
ifaddr = mnl_nlmsg_put_extra_header(nlh, sizeof(struct ifaddrmsg));
ifaddr->ifa_family = addr->family;
ifaddr->ifa_prefixlen = addr->cidr;
ifaddr->ifa_scope = RT_SCOPE_UNIVERSE; /* linux/rtnetlink.h */
ifaddr->ifa_index = ifindex;
mnl_attr_put(nlh, IFA_LOCAL, addr->family == AF_INET ? 4 : 16, addr);
if (mnl_socket_sendto(nl, nlh, nlh->nlmsg_len) < 0)
fatal("mnl_socket_sendto");
do {
ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
if (ret <= MNL_CB_STOP)
break;
ret = mnl_cb_run(buf, ret, seq, portid, NULL, NULL);
} while (ret > 0);
if (ret == -1)
fatal("mnl_cb_run/mnl_socket_recvfrom");
}
static int data_cb(const struct nlmsghdr *nlh, void *data)
{
struct nlattr *tb[IFA_MAX + 1] = {};
struct ifaddrmsg *ifa = mnl_nlmsg_get_payload(nlh);
struct mnl_cb_data *cb_data = (struct mnl_cb_data *)data;
if (ifa->ifa_index != cb_data->ifindex)
return MNL_CB_OK;
if (ifa->ifa_scope != RT_SCOPE_LINK)
return MNL_CB_OK;
mnl_attr_parse(nlh, sizeof(*ifa), data_attr_cb, tb);
if (!tb[IFA_ADDRESS])
return MNL_CB_OK;
if (cb_data->ip_found) {
cb_data->duplicate = true;
return MNL_CB_OK;
}
memcpy(cb_data->ip, mnl_attr_get_payload(tb[IFA_ADDRESS]),
ifa->ifa_family == AF_INET ? 4 : 16);
cb_data->ip->cidr = ifa->ifa_prefixlen;
cb_data->ip->family = ifa->ifa_family;
char out[INET6_ADDRSTRLEN];
inet_ntop(ifa->ifa_family, cb_data->ip, out, sizeof(out));
debug("index=%d, family=%d, addr=%s\n", ifa->ifa_index, ifa->ifa_family,
out);
cb_data->ip_found = true;
return MNL_CB_OK;
}
static void iface_get_all_addrs2(uint8_t family, mnl_cb_t data_cb,
void *cb_data)
{
char buf[MNL_SOCKET_BUFFER_SIZE];
struct nlmsghdr *nlh;
/* TODO: rtln-addr-dump from libmnl uses rtgenmsg here? */
struct ifaddrmsg *ifaddr;
int ret;
unsigned int seq, portid;
/* You'd think that we could just request addresses from a specific
* interface, via NLM_F_MATCH or something, but we can't. See also:
* https://marc.info/?l=linux-netdev&m=132508164508217
*/
seq = time(NULL);
portid = mnl_socket_get_portid(nl);
nlh = mnl_nlmsg_put_header(buf);
nlh->nlmsg_type = RTM_GETADDR;
nlh->nlmsg_flags = NLM_F_REQUEST | NLM_F_DUMP;
nlh->nlmsg_seq = seq;
ifaddr = mnl_nlmsg_put_extra_header(nlh, sizeof(struct ifaddrmsg));
ifaddr->ifa_family = family;
if (mnl_socket_sendto(nl, nlh, nlh->nlmsg_len) < 0)
fatal("mnl_socket_sendto");
do {
ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
if (ret <= MNL_CB_STOP)
break;
ret = mnl_cb_run(buf, ret, seq, portid, data_cb, cb_data);
} while (ret > 0);
if (ret == -1)
fatal("mnl_cb_run/mnl_socket_recvfrom");
}
void ipm_init()
{
nl = mnl_socket_open(NETLINK_ROUTE);
if (nl == NULL)
fatal("mnl_socket_open()");
if (mnl_socket_bind(nl, 0, MNL_SOCKET_AUTOPID) < 0)
fatal("mnl_socket_bind()");
}
void ipm_free()
{
if (nl)
mnl_socket_close(nl);
}
void ipm_newaddr(uint32_t ifindex, const struct wg_combined_ip *addr)
{
iface_update(RTM_NEWADDR, NLM_F_REPLACE | NLM_F_CREATE, ifindex, addr);
}
void ipm_deladdr(uint32_t ifindex, const struct wg_combined_ip *addr)
{
iface_update(RTM_DELADDR, 0, ifindex, addr);
}
int ipm_getlladdr(uint32_t ifindex, struct wg_combined_ip *addr)
{
struct mnl_cb_data cb_data = {
.ifindex = ifindex,
.ip = addr,
.ip_found = false,
.duplicate = false,
};
iface_get_all_addrs2(AF_INET6, data_cb, &cb_data);
if (!cb_data.ip_found)
return -1;
if (cb_data.duplicate)
return -2;
return 0;
}
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