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/* Copyright 2015-2016 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved. */
#include <errno.h>
#include <libmnl/libmnl.h>
#include <linux/if_link.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#include <netinet/in.h>
#include <net/if.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <sys/ioctl.h>
#include <time.h>
#include "kernel.h"
#include "../uapi.h"
struct inflatable_buffer {
char *buffer;
char *next;
bool good;
size_t len;
size_t pos;
};
#define max(a, b) (a > b ? a : b)
static int add_next_to_inflatable_buffer(struct inflatable_buffer *buffer)
{
size_t len, expand_to;
char *new_buffer;
if (!buffer->good || !buffer->next) {
free(buffer->next);
return 0;
}
len = strlen(buffer->next) + 1;
if (len == 1)
return 0;
if (buffer->len - buffer->pos <= len) {
expand_to = max(buffer->len * 2, buffer->len + len + 1);
new_buffer = realloc(buffer->buffer, expand_to);
if (!new_buffer) {
free(buffer->next);
return -errno;
}
memset(&new_buffer[buffer->len], 0, expand_to - buffer->len);
buffer->buffer = new_buffer;
buffer->len = expand_to;
}
memcpy(&buffer->buffer[buffer->pos], buffer->next, len);
free(buffer->next);
buffer->pos += len;
return 0;
}
static int parse_linkinfo(const struct nlattr *attr, void *data)
{
struct inflatable_buffer *buffer = data;
if (mnl_attr_get_type(attr) == IFLA_INFO_KIND && !strcmp("wireguard", mnl_attr_get_str(attr)))
buffer->good = true;
return MNL_CB_OK;
}
static int parse_infomsg(const struct nlattr *attr, void *data)
{
struct inflatable_buffer *buffer = data;
if (mnl_attr_get_type(attr) == IFLA_LINKINFO)
return mnl_attr_parse_nested(attr, parse_linkinfo, data);
else if (mnl_attr_get_type(attr) == IFLA_IFNAME)
buffer->next = strdup(mnl_attr_get_str(attr));
return MNL_CB_OK;
}
static int read_devices_cb(const struct nlmsghdr *nlh, void *data)
{
struct inflatable_buffer *buffer = data;
buffer->good = false;
buffer->next = NULL;
int ret = mnl_attr_parse(nlh, sizeof(struct ifinfomsg), parse_infomsg, data);
if (ret != MNL_CB_OK)
return ret;
ret = add_next_to_inflatable_buffer(buffer);
if (ret < 0)
return ret;
if (nlh->nlmsg_type != NLMSG_DONE)
return MNL_CB_OK + 1;
return MNL_CB_OK;
}
/* first\0second\0third\0forth\0last\0\0 */
char *kernel_get_wireguard_interfaces(void)
{
struct mnl_socket *nl = NULL;
char *rtnl_buffer = NULL;
size_t message_len;
unsigned int portid, seq;
ssize_t len;
int ret = 0;
struct inflatable_buffer buffer = { 0 };
struct nlmsghdr *nlh;
struct ifinfomsg *ifm;
buffer.len = 4096;
buffer.buffer = calloc(buffer.len, 1);
if (!buffer.buffer) {
ret = -errno;
goto cleanup;
}
rtnl_buffer = calloc(4096, 1);
if (!rtnl_buffer) {
ret = -errno;
goto cleanup;
}
nl = mnl_socket_open(NETLINK_ROUTE);
if (!nl) {
ret = -errno;
goto cleanup;
}
if (mnl_socket_bind(nl, 0, MNL_SOCKET_AUTOPID) < 0) {
ret = -errno;
goto cleanup;
}
seq = time(NULL);
portid = mnl_socket_get_portid(nl);
nlh = mnl_nlmsg_put_header(rtnl_buffer);
nlh->nlmsg_type = RTM_GETLINK;
nlh->nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK | NLM_F_DUMP;
nlh->nlmsg_seq = seq;
ifm = mnl_nlmsg_put_extra_header(nlh, sizeof(*ifm));
ifm->ifi_family = AF_UNSPEC;
message_len = nlh->nlmsg_len;
if (mnl_socket_sendto(nl, rtnl_buffer, message_len) < 0) {
ret = -errno;
goto cleanup;
}
another:
if ((len = mnl_socket_recvfrom(nl, rtnl_buffer, 4096)) < 0) {
ret = -errno;
goto cleanup;
}
if ((len = mnl_cb_run(rtnl_buffer, len, seq, portid, read_devices_cb, &buffer)) < 0) {
ret = -errno;
goto cleanup;
}
if (len == MNL_CB_OK + 1)
goto another;
cleanup:
free(rtnl_buffer);
if (nl)
mnl_socket_close(nl);
errno = -ret;
if (errno) {
perror("Error when trying to get a list of Wireguard interfaces");
free(buffer.buffer);
return NULL;
}
return buffer.buffer;
}
bool kernel_has_wireguard_interface(const char *interface)
{
char *interfaces, *this_interface;
this_interface = interfaces = kernel_get_wireguard_interfaces();
if (!interfaces)
return false;
for (size_t len = 0; (len = strlen(this_interface)); this_interface += len + 1) {
if (!strcmp(interface, this_interface)) {
free(interfaces);
return true;
}
}
free(interfaces);
return false;
}
static int do_ioctl(int req, struct ifreq *ifreq)
{
static int fd = -1;
if (fd < 0) {
fd = socket(AF_INET, SOCK_DGRAM, 0);
if (fd < 0)
return fd;
}
return ioctl(fd, req, ifreq);
}
int kernel_set_device(struct wgdevice *dev)
{
struct ifreq ifreq = { .ifr_data = (char *)dev };
memcpy(&ifreq.ifr_name, dev->interface, IFNAMSIZ);
ifreq.ifr_name[IFNAMSIZ - 1] = 0;
return do_ioctl(WG_SET_DEVICE, &ifreq);
}
int kernel_get_device(struct wgdevice **dev, const char *interface)
{
int ret;
struct ifreq ifreq = { 0 };
memcpy(&ifreq.ifr_name, interface, IFNAMSIZ);
ifreq.ifr_name[IFNAMSIZ - 1] = 0;
*dev = NULL;
do {
free(*dev);
ret = do_ioctl(WG_GET_DEVICE, &ifreq);
if (ret < 0)
goto out;
*dev = calloc(ret + sizeof(struct wgdevice), 1);
if (!*dev) {
perror("calloc");
ret = -ENOMEM;
goto out;
}
(*dev)->peers_size = ret;
ifreq.ifr_data = (char *)*dev;
memcpy(&ifreq.ifr_name, interface, IFNAMSIZ);
ifreq.ifr_name[IFNAMSIZ - 1] = 0;
ret = do_ioctl(WG_GET_DEVICE, &ifreq);
} while (ret == -EMSGSIZE);
if (ret < 0) {
free(*dev);
*dev = NULL;
}
out:
errno = -ret;
return ret;
}
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