Initialize project with scafolding and embeddable-wg-library

1 files changed, 991 insertions, 0 deletions

diff --git a/netlink.c b/netlink.c
new file mode 100644
index 0000000..aea8eac
--- /dev/null
+++ b/netlink.c
@@ -0,0 +1,991 @@
+// SPDX-License-Identifier: LGPL-2.1+
+/*
+ * Copyright (C) 2015-2019 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
+ * Copyright (C) 2008-2012 Pablo Neira Ayuso <pablo@netfilter.org>.
+ */
+
+#include <errno.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <assert.h>
+
+#include <libmnl/libmnl.h>
+#include <linux/if_link.h>
+#include <linux/netlink.h>
+#include <linux/rtnetlink.h>
+#include <linux/genetlink.h>
+
+#include "netlink.h"
+
+#define WG_GENL_NAME "wireguard"
+#define WG_GENL_VERSION 1
+
+enum wg_cmd {
+	WG_CMD_GET_DEVICE,
+	WG_CMD_SET_DEVICE,
+	__WG_CMD_MAX
+};
+
+enum wgdevice_flag {
+	WGDEVICE_F_REPLACE_PEERS = 1U << 0
+};
+enum wgdevice_attribute {
+	WGDEVICE_A_UNSPEC,
+	WGDEVICE_A_IFINDEX,
+	WGDEVICE_A_IFNAME,
+	WGDEVICE_A_PRIVATE_KEY,
+	WGDEVICE_A_PUBLIC_KEY,
+	WGDEVICE_A_FLAGS,
+	WGDEVICE_A_LISTEN_PORT,
+	WGDEVICE_A_FWMARK,
+	WGDEVICE_A_PEERS,
+	__WGDEVICE_A_LAST
+};
+
+enum wgpeer_flag {
+	WGPEER_F_REMOVE_ME = 1U << 0,
+	WGPEER_F_REPLACE_ALLOWEDIPS = 1U << 1
+};
+enum wgpeer_attribute {
+	WGPEER_A_UNSPEC,
+	WGPEER_A_PUBLIC_KEY,
+	WGPEER_A_PRESHARED_KEY,
+	WGPEER_A_FLAGS,
+	WGPEER_A_ENDPOINT,
+	WGPEER_A_PERSISTENT_KEEPALIVE_INTERVAL,
+	WGPEER_A_LAST_HANDSHAKE_TIME,
+	WGPEER_A_RX_BYTES,
+	WGPEER_A_TX_BYTES,
+	WGPEER_A_ALLOWEDIPS,
+	WGPEER_A_PROTOCOL_VERSION,
+	__WGPEER_A_LAST
+};
+
+enum wgallowedip_attribute {
+	WGALLOWEDIP_A_UNSPEC,
+	WGALLOWEDIP_A_FAMILY,
+	WGALLOWEDIP_A_IPADDR,
+	WGALLOWEDIP_A_CIDR_MASK,
+	__WGALLOWEDIP_A_LAST
+};
+
+struct mnlg_socket {
+	struct mnl_socket *nl;
+	char *buf;
+	uint16_t id;
+	uint8_t version;
+	unsigned int seq;
+	unsigned int portid;
+};
+
+static struct nlmsghdr *__mnlg_msg_prepare(struct mnlg_socket *nlg, uint8_t cmd,
+					   uint16_t flags, uint16_t id,
+					   uint8_t version)
+{
+	struct nlmsghdr *nlh;
+	struct genlmsghdr *genl;
+
+	nlh = mnl_nlmsg_put_header(nlg->buf);
+	nlh->nlmsg_type	= id;
+	nlh->nlmsg_flags = flags;
+	nlg->seq = time(NULL);
+	nlh->nlmsg_seq = nlg->seq;
+
+	genl = mnl_nlmsg_put_extra_header(nlh, sizeof(struct genlmsghdr));
+	genl->cmd = cmd;
+	genl->version = version;
+
+	return nlh;
+}
+
+static struct nlmsghdr *mnlg_msg_prepare(struct mnlg_socket *nlg, uint8_t cmd,
+					 uint16_t flags)
+{
+	return __mnlg_msg_prepare(nlg, cmd, flags, nlg->id, nlg->version);
+}
+
+static int mnlg_socket_send(struct mnlg_socket *nlg, const struct nlmsghdr *nlh)
+{
+	return mnl_socket_sendto(nlg->nl, nlh, nlh->nlmsg_len);
+}
+
+static int mnlg_cb_noop(const struct nlmsghdr *nlh, void *data)
+{
+	(void)nlh;
+	(void)data;
+	return MNL_CB_OK;
+}
+
+static int mnlg_cb_error(const struct nlmsghdr *nlh, void *data)
+{
+	const struct nlmsgerr *err = mnl_nlmsg_get_payload(nlh);
+	(void)data;
+
+	if (nlh->nlmsg_len < mnl_nlmsg_size(sizeof(struct nlmsgerr))) {
+		errno = EBADMSG;
+		return MNL_CB_ERROR;
+	}
+	/* Netlink subsystems returns the errno value with different signess */
+	if (err->error < 0)
+		errno = -err->error;
+	else
+		errno = err->error;
+
+	return err->error == 0 ? MNL_CB_STOP : MNL_CB_ERROR;
+}
+
+static int mnlg_cb_stop(const struct nlmsghdr *nlh, void *data)
+{
+	(void)data;
+	if (nlh->nlmsg_flags & NLM_F_MULTI && nlh->nlmsg_len == mnl_nlmsg_size(sizeof(int))) {
+		int error = *(int *)mnl_nlmsg_get_payload(nlh);
+		/* Netlink subsystems returns the errno value with different signess */
+		if (error < 0)
+			errno = -error;
+		else
+			errno = error;
+
+		return error == 0 ? MNL_CB_STOP : MNL_CB_ERROR;
+	}
+	return MNL_CB_STOP;
+}
+
+static mnl_cb_t mnlg_cb_array[] = {
+	[NLMSG_NOOP]	= mnlg_cb_noop,
+	[NLMSG_ERROR]	= mnlg_cb_error,
+	[NLMSG_DONE]	= mnlg_cb_stop,
+	[NLMSG_OVERRUN]	= mnlg_cb_noop,
+};
+
+static int mnlg_socket_recv_run(struct mnlg_socket *nlg, mnl_cb_t data_cb, void *data)
+{
+	int err;
+
+	do {
+		err = mnl_socket_recvfrom(nlg->nl, nlg->buf,
+					  MNL_SOCKET_BUFFER_SIZE);
+		if (err <= 0)
+			break;
+		err = mnl_cb_run2(nlg->buf, err, nlg->seq, nlg->portid,
+				  data_cb, data, mnlg_cb_array, MNL_ARRAY_SIZE(mnlg_cb_array));
+	} while (err > 0);
+
+	return err;
+}
+
+static int get_family_id_attr_cb(const struct nlattr *attr, void *data)
+{
+	const struct nlattr **tb = data;
+	int type = mnl_attr_get_type(attr);
+
+	if (mnl_attr_type_valid(attr, CTRL_ATTR_MAX) < 0)
+		return MNL_CB_ERROR;
+
+	if (type == CTRL_ATTR_FAMILY_ID &&
+	    mnl_attr_validate(attr, MNL_TYPE_U16) < 0)
+		return MNL_CB_ERROR;
+	tb[type] = attr;
+	return MNL_CB_OK;
+}
+
+static int get_family_id_cb(const struct nlmsghdr *nlh, void *data)
+{
+	uint16_t *p_id = data;
+	struct nlattr *tb[CTRL_ATTR_MAX + 1] = { 0 };
+
+	mnl_attr_parse(nlh, sizeof(struct genlmsghdr), get_family_id_attr_cb, tb);
+	if (!tb[CTRL_ATTR_FAMILY_ID])
+		return MNL_CB_ERROR;
+	*p_id = mnl_attr_get_u16(tb[CTRL_ATTR_FAMILY_ID]);
+	return MNL_CB_OK;
+}
+
+static struct mnlg_socket *mnlg_socket_open(const char *family_name, uint8_t version)
+{
+	struct mnlg_socket *nlg;
+	struct nlmsghdr *nlh;
+	int err;
+
+	nlg = malloc(sizeof(*nlg));
+	if (!nlg)
+		return NULL;
+
+	err = -ENOMEM;
+	nlg->buf = malloc(MNL_SOCKET_BUFFER_SIZE);
+	if (!nlg->buf)
+		goto err_buf_alloc;
+
+	nlg->nl = mnl_socket_open(NETLINK_GENERIC);
+	if (!nlg->nl) {
+		err = -errno;
+		goto err_mnl_socket_open;
+	}
+
+	if (mnl_socket_bind(nlg->nl, 0, MNL_SOCKET_AUTOPID) < 0) {
+		err = -errno;
+		goto err_mnl_socket_bind;
+	}
+
+	nlg->portid = mnl_socket_get_portid(nlg->nl);
+
+	nlh = __mnlg_msg_prepare(nlg, CTRL_CMD_GETFAMILY,
+				 NLM_F_REQUEST | NLM_F_ACK, GENL_ID_CTRL, 1);
+	mnl_attr_put_strz(nlh, CTRL_ATTR_FAMILY_NAME, family_name);
+
+	if (mnlg_socket_send(nlg, nlh) < 0) {
+		err = -errno;
+		goto err_mnlg_socket_send;
+	}
+
+	errno = 0;
+	if (mnlg_socket_recv_run(nlg, get_family_id_cb, &nlg->id) < 0) {
+		errno = errno == ENOENT ? EPROTONOSUPPORT : errno;
+		err = errno ? -errno : -ENOSYS;
+		goto err_mnlg_socket_recv_run;
+	}
+
+	nlg->version = version;
+	errno = 0;
+	return nlg;
+
+err_mnlg_socket_recv_run:
+err_mnlg_socket_send:
+err_mnl_socket_bind:
+	mnl_socket_close(nlg->nl);
+err_mnl_socket_open:
+	free(nlg->buf);
+err_buf_alloc:
+	free(nlg);
+	errno = -err;
+	return NULL;
+}
+
+static void mnlg_socket_close(struct mnlg_socket *nlg)
+{
+	mnl_socket_close(nlg->nl);
+	free(nlg->buf);
+	free(nlg);
+}
+
+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);
+		buffer->good = false;
+		return 0;
+	}
+
+	len = strlen(buffer->next) + 1;
+
+	if (len == 1) {
+		free(buffer->next);
+		buffer->good = false;
+		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);
+			buffer->good = false;
+			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->good = false;
+	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(WG_GENL_NAME, 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;
+	int ret;
+
+	buffer->good = false;
+	buffer->next = NULL;
+	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;
+}
+
+static int fetch_device_names(struct inflatable_buffer *buffer)
+{
+	struct mnl_socket *nl = NULL;
+	char *rtnl_buffer = NULL;
+	size_t message_len;
+	unsigned int portid, seq;
+	ssize_t len;
+	int ret = 0;
+	struct nlmsghdr *nlh;
+	struct ifinfomsg *ifm;
+
+	ret = -ENOMEM;
+	rtnl_buffer = calloc(MNL_SOCKET_BUFFER_SIZE, 1);
+	if (!rtnl_buffer)
+		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, MNL_SOCKET_BUFFER_SIZE)) < 0) {
+		ret = -errno;
+		goto cleanup;
+	}
+	if ((len = mnl_cb_run(rtnl_buffer, len, seq, portid, read_devices_cb, buffer)) < 0) {
+		/* Netlink returns NLM_F_DUMP_INTR if the set of all tunnels changed
+		 * during the dump. That's unfortunate, but is pretty common on busy
+		 * systems that are adding and removing tunnels all the time. Rather
+		 * than retrying, potentially indefinitely, we just work with the
+		 * partial results. */
+		if (errno != EINTR) {
+			ret = -errno;
+			goto cleanup;
+		}
+	}
+	if (len == MNL_CB_OK + 1)
+		goto another;
+	ret = 0;
+
+cleanup:
+	free(rtnl_buffer);
+	if (nl)
+		mnl_socket_close(nl);
+	return ret;
+}
+
+static int add_del_iface(const char *ifname, bool add)
+{
+	struct mnl_socket *nl = NULL;
+	char *rtnl_buffer;
+	ssize_t len;
+	int ret;
+	struct nlmsghdr *nlh;
+	struct ifinfomsg *ifm;
+	struct nlattr *nest;
+
+	rtnl_buffer = calloc(MNL_SOCKET_BUFFER_SIZE, 1);
+	if (!rtnl_buffer) {
+		ret = -ENOMEM;
+		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;
+	}
+
+	nlh = mnl_nlmsg_put_header(rtnl_buffer);
+	nlh->nlmsg_type = add ? RTM_NEWLINK : RTM_DELLINK;
+	nlh->nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK | (add ? NLM_F_CREATE | NLM_F_EXCL : 0);
+	nlh->nlmsg_seq = time(NULL);
+	ifm = mnl_nlmsg_put_extra_header(nlh, sizeof(*ifm));
+	ifm->ifi_family = AF_UNSPEC;
+	mnl_attr_put_strz(nlh, IFLA_IFNAME, ifname);
+	nest = mnl_attr_nest_start(nlh, IFLA_LINKINFO);
+	mnl_attr_put_strz(nlh, IFLA_INFO_KIND, WG_GENL_NAME);
+	mnl_attr_nest_end(nlh, nest);
+
+	if (mnl_socket_sendto(nl, rtnl_buffer, nlh->nlmsg_len) < 0) {
+		ret = -errno;
+		goto cleanup;
+	}
+	if ((len = mnl_socket_recvfrom(nl, rtnl_buffer, MNL_SOCKET_BUFFER_SIZE)) < 0) {
+		ret = -errno;
+		goto cleanup;
+	}
+	if (mnl_cb_run(rtnl_buffer, len, nlh->nlmsg_seq, mnl_socket_get_portid(nl), NULL, NULL) < 0) {
+		ret = -errno;
+		goto cleanup;
+	}
+	ret = 0;
+
+cleanup:
+	free(rtnl_buffer);
+	if (nl)
+		mnl_socket_close(nl);
+	return ret;
+}
+
+int wg_set_device(wg_device *dev)
+{
+	int ret = 0;
+	wg_peer *peer = NULL;
+	wg_allowedip *allowedip = NULL;
+	struct nlattr *peers_nest, *peer_nest, *allowedips_nest, *allowedip_nest;
+	struct nlmsghdr *nlh;
+	struct mnlg_socket *nlg;
+
+	nlg = mnlg_socket_open(WG_GENL_NAME, WG_GENL_VERSION);
+	if (!nlg)
+		return -errno;
+
+again:
+	nlh = mnlg_msg_prepare(nlg, WG_CMD_SET_DEVICE, NLM_F_REQUEST | NLM_F_ACK);
+	mnl_attr_put_strz(nlh, WGDEVICE_A_IFNAME, dev->name);
+
+	if (!peer) {
+		uint32_t flags = 0;
+
+		if (dev->flags & WGDEVICE_HAS_PRIVATE_KEY)
+			mnl_attr_put(nlh, WGDEVICE_A_PRIVATE_KEY, sizeof(dev->private_key), dev->private_key);
+		if (dev->flags & WGDEVICE_HAS_LISTEN_PORT)
+			mnl_attr_put_u16(nlh, WGDEVICE_A_LISTEN_PORT, dev->listen_port);
+		if (dev->flags & WGDEVICE_HAS_FWMARK)
+			mnl_attr_put_u32(nlh, WGDEVICE_A_FWMARK, dev->fwmark);
+		if (dev->flags & WGDEVICE_REPLACE_PEERS)
+			flags |= WGDEVICE_F_REPLACE_PEERS;
+		if (flags)
+			mnl_attr_put_u32(nlh, WGDEVICE_A_FLAGS, flags);
+	}
+	if (!dev->first_peer)
+		goto send;
+	peers_nest = peer_nest = allowedips_nest = allowedip_nest = NULL;
+	peers_nest = mnl_attr_nest_start(nlh, WGDEVICE_A_PEERS);
+	for (peer = peer ? peer : dev->first_peer; peer; peer = peer->next_peer) {
+		uint32_t flags = 0;
+
+		peer_nest = mnl_attr_nest_start_check(nlh, MNL_SOCKET_BUFFER_SIZE, 0);
+		if (!peer_nest)
+			goto toobig_peers;
+		if (!mnl_attr_put_check(nlh, MNL_SOCKET_BUFFER_SIZE, WGPEER_A_PUBLIC_KEY, sizeof(peer->public_key), peer->public_key))
+			goto toobig_peers;
+		if (peer->flags & WGPEER_REMOVE_ME)
+			flags |= WGPEER_F_REMOVE_ME;
+		if (!allowedip) {
+			if (peer->flags & WGPEER_REPLACE_ALLOWEDIPS)
+				flags |= WGPEER_F_REPLACE_ALLOWEDIPS;
+			if (peer->flags & WGPEER_HAS_PRESHARED_KEY) {
+				if (!mnl_attr_put_check(nlh, MNL_SOCKET_BUFFER_SIZE, WGPEER_A_PRESHARED_KEY, sizeof(peer->preshared_key), peer->preshared_key))
+					goto toobig_peers;
+			}
+			if (peer->endpoint.addr.sa_family == AF_INET) {
+				if (!mnl_attr_put_check(nlh, MNL_SOCKET_BUFFER_SIZE, WGPEER_A_ENDPOINT, sizeof(peer->endpoint.addr4), &peer->endpoint.addr4))
+					goto toobig_peers;
+			} else if (peer->endpoint.addr.sa_family == AF_INET6) {
+				if (!mnl_attr_put_check(nlh, MNL_SOCKET_BUFFER_SIZE, WGPEER_A_ENDPOINT, sizeof(peer->endpoint.addr6), &peer->endpoint.addr6))
+					goto toobig_peers;
+			}
+			if (peer->flags & WGPEER_HAS_PERSISTENT_KEEPALIVE_INTERVAL) {
+				if (!mnl_attr_put_u16_check(nlh, MNL_SOCKET_BUFFER_SIZE, WGPEER_A_PERSISTENT_KEEPALIVE_INTERVAL, peer->persistent_keepalive_interval))
+					goto toobig_peers;
+			}
+		}
+		if (flags) {
+			if (!mnl_attr_put_u32_check(nlh, MNL_SOCKET_BUFFER_SIZE, WGPEER_A_FLAGS, flags))
+				goto toobig_peers;
+		}
+		if (peer->first_allowedip) {
+			if (!allowedip)
+				allowedip = peer->first_allowedip;
+			allowedips_nest = mnl_attr_nest_start_check(nlh, MNL_SOCKET_BUFFER_SIZE, WGPEER_A_ALLOWEDIPS);
+			if (!allowedips_nest)
+				goto toobig_allowedips;
+			for (; allowedip; allowedip = allowedip->next_allowedip) {
+				allowedip_nest = mnl_attr_nest_start_check(nlh, MNL_SOCKET_BUFFER_SIZE, 0);
+				if (!allowedip_nest)
+					goto toobig_allowedips;
+				if (!mnl_attr_put_u16_check(nlh, MNL_SOCKET_BUFFER_SIZE, WGALLOWEDIP_A_FAMILY, allowedip->family))
+					goto toobig_allowedips;
+				if (allowedip->family == AF_INET) {
+					if (!mnl_attr_put_check(nlh, MNL_SOCKET_BUFFER_SIZE, WGALLOWEDIP_A_IPADDR, sizeof(allowedip->ip4), &allowedip->ip4))
+						goto toobig_allowedips;
+				} else if (allowedip->family == AF_INET6) {
+					if (!mnl_attr_put_check(nlh, MNL_SOCKET_BUFFER_SIZE, WGALLOWEDIP_A_IPADDR, sizeof(allowedip->ip6), &allowedip->ip6))
+						goto toobig_allowedips;
+				}
+				if (!mnl_attr_put_u8_check(nlh, MNL_SOCKET_BUFFER_SIZE, WGALLOWEDIP_A_CIDR_MASK, allowedip->cidr))
+					goto toobig_allowedips;
+				mnl_attr_nest_end(nlh, allowedip_nest);
+				allowedip_nest = NULL;
+			}
+			mnl_attr_nest_end(nlh, allowedips_nest);
+			allowedips_nest = NULL;
+		}
+
+		mnl_attr_nest_end(nlh, peer_nest);
+		peer_nest = NULL;
+	}
+	mnl_attr_nest_end(nlh, peers_nest);
+	peers_nest = NULL;
+	goto send;
+toobig_allowedips:
+	if (allowedip_nest)
+		mnl_attr_nest_cancel(nlh, allowedip_nest);
+	if (allowedips_nest)
+		mnl_attr_nest_end(nlh, allowedips_nest);
+	mnl_attr_nest_end(nlh, peer_nest);
+	mnl_attr_nest_end(nlh, peers_nest);
+	goto send;
+toobig_peers:
+	if (peer_nest)
+		mnl_attr_nest_cancel(nlh, peer_nest);
+	mnl_attr_nest_end(nlh, peers_nest);
+	goto send;
+send:
+	if (mnlg_socket_send(nlg, nlh) < 0) {
+		ret = -errno;
+		goto out;
+	}
+	errno = 0;
+	if (mnlg_socket_recv_run(nlg, NULL, NULL) < 0) {
+		ret = errno ? -errno : -EINVAL;
+		goto out;
+	}
+	if (peer)
+		goto again;
+
+out:
+	mnlg_socket_close(nlg);
+	errno = -ret;
+	return ret;
+}
+
+static int parse_allowedip(const struct nlattr *attr, void *data)
+{
+	wg_allowedip *allowedip = data;
+
+	switch (mnl_attr_get_type(attr)) {
+	case WGALLOWEDIP_A_UNSPEC:
+		break;
+	case WGALLOWEDIP_A_FAMILY:
+		if (!mnl_attr_validate(attr, MNL_TYPE_U16))
+			allowedip->family = mnl_attr_get_u16(attr);
+		break;
+	case WGALLOWEDIP_A_IPADDR:
+		if (mnl_attr_get_payload_len(attr) == sizeof(allowedip->ip4))
+			memcpy(&allowedip->ip4, mnl_attr_get_payload(attr), sizeof(allowedip->ip4));
+		else if (mnl_attr_get_payload_len(attr) == sizeof(allowedip->ip6))
+			memcpy(&allowedip->ip6, mnl_attr_get_payload(attr), sizeof(allowedip->ip6));
+		break;
+	case WGALLOWEDIP_A_CIDR_MASK:
+		if (!mnl_attr_validate(attr, MNL_TYPE_U8))
+			allowedip->cidr = mnl_attr_get_u8(attr);
+		break;
+	}
+
+	return MNL_CB_OK;
+}
+
+static int parse_allowedips(const struct nlattr *attr, void *data)
+{
+	wg_peer *peer = data;
+	wg_allowedip *new_allowedip = calloc(1, sizeof(wg_allowedip));
+	int ret;
+
+	if (!new_allowedip)
+		return MNL_CB_ERROR;
+	if (!peer->first_allowedip)
+		peer->first_allowedip = peer->last_allowedip = new_allowedip;
+	else {
+		peer->last_allowedip->next_allowedip = new_allowedip;
+		peer->last_allowedip = new_allowedip;
+	}
+	ret = mnl_attr_parse_nested(attr, parse_allowedip, new_allowedip);
+	if (!ret)
+		return ret;
+	if (!((new_allowedip->family == AF_INET && new_allowedip->cidr <= 32) || (new_allowedip->family == AF_INET6 && new_allowedip->cidr <= 128))) {
+		errno = EAFNOSUPPORT;
+		return MNL_CB_ERROR;
+	}
+	return MNL_CB_OK;
+}
+
+bool wg_key_is_zero(const wg_key key)
+{
+	volatile uint8_t acc = 0;
+	unsigned int i;
+
+	for (i = 0; i < sizeof(wg_key); ++i) {
+		acc |= key[i];
+		__asm__ ("" : "=r" (acc) : "0" (acc));
+	}
+	return 1 & ((acc - 1) >> 8);
+}
+
+static int parse_peer(const struct nlattr *attr, void *data)
+{
+	wg_peer *peer = data;
+
+	switch (mnl_attr_get_type(attr)) {
+	case WGPEER_A_UNSPEC:
+		break;
+	case WGPEER_A_PUBLIC_KEY:
+		if (mnl_attr_get_payload_len(attr) == sizeof(peer->public_key)) {
+			memcpy(peer->public_key, mnl_attr_get_payload(attr), sizeof(peer->public_key));
+			peer->flags |= WGPEER_HAS_PUBLIC_KEY;
+		}
+		break;
+	case WGPEER_A_PRESHARED_KEY:
+		if (mnl_attr_get_payload_len(attr) == sizeof(peer->preshared_key)) {
+			memcpy(peer->preshared_key, mnl_attr_get_payload(attr), sizeof(peer->preshared_key));
+			if (!wg_key_is_zero(peer->preshared_key))
+				peer->flags |= WGPEER_HAS_PRESHARED_KEY;
+		}
+		break;
+	case WGPEER_A_ENDPOINT: {
+		struct sockaddr *addr;
+
+		if (mnl_attr_get_payload_len(attr) < sizeof(*addr))
+			break;
+		addr = mnl_attr_get_payload(attr);
+		if (addr->sa_family == AF_INET && mnl_attr_get_payload_len(attr) == sizeof(peer->endpoint.addr4))
+			memcpy(&peer->endpoint.addr4, addr, sizeof(peer->endpoint.addr4));
+		else if (addr->sa_family == AF_INET6 && mnl_attr_get_payload_len(attr) == sizeof(peer->endpoint.addr6))
+			memcpy(&peer->endpoint.addr6, addr, sizeof(peer->endpoint.addr6));
+		break;
+	}
+	case WGPEER_A_PERSISTENT_KEEPALIVE_INTERVAL:
+		if (!mnl_attr_validate(attr, MNL_TYPE_U16))
+			peer->persistent_keepalive_interval = mnl_attr_get_u16(attr);
+		break;
+	case WGPEER_A_LAST_HANDSHAKE_TIME:
+		if (mnl_attr_get_payload_len(attr) == sizeof(peer->last_handshake_time))
+			memcpy(&peer->last_handshake_time, mnl_attr_get_payload(attr), sizeof(peer->last_handshake_time));
+		break;
+	case WGPEER_A_RX_BYTES:
+		if (!mnl_attr_validate(attr, MNL_TYPE_U64))
+			peer->rx_bytes = mnl_attr_get_u64(attr);
+		break;
+	case WGPEER_A_TX_BYTES:
+		if (!mnl_attr_validate(attr, MNL_TYPE_U64))
+			peer->tx_bytes = mnl_attr_get_u64(attr);
+		break;
+	case WGPEER_A_ALLOWEDIPS:
+		return mnl_attr_parse_nested(attr, parse_allowedips, peer);
+	}
+
+	return MNL_CB_OK;
+}
+
+static int parse_peers(const struct nlattr *attr, void *data)
+{
+	wg_device *device = data;
+	wg_peer *new_peer = calloc(1, sizeof(wg_peer));
+	int ret;
+
+	if (!new_peer)
+		return MNL_CB_ERROR;
+	if (!device->first_peer)
+		device->first_peer = device->last_peer = new_peer;
+	else {
+		device->last_peer->next_peer = new_peer;
+		device->last_peer = new_peer;
+	}
+	ret = mnl_attr_parse_nested(attr, parse_peer, new_peer);
+	if (!ret)
+		return ret;
+	if (!(new_peer->flags & WGPEER_HAS_PUBLIC_KEY)) {
+		errno = ENXIO;
+		return MNL_CB_ERROR;
+	}
+	return MNL_CB_OK;
+}
+
+static int parse_device(const struct nlattr *attr, void *data)
+{
+	wg_device *device = data;
+
+	switch (mnl_attr_get_type(attr)) {
+	case WGDEVICE_A_UNSPEC:
+		break;
+	case WGDEVICE_A_IFINDEX:
+		if (!mnl_attr_validate(attr, MNL_TYPE_U32))
+			device->ifindex = mnl_attr_get_u32(attr);
+		break;
+	case WGDEVICE_A_IFNAME:
+		if (!mnl_attr_validate(attr, MNL_TYPE_STRING)) {
+			strncpy(device->name, mnl_attr_get_str(attr), sizeof(device->name) - 1);
+			device->name[sizeof(device->name) - 1] = '\0';
+		}
+		break;
+	case WGDEVICE_A_PRIVATE_KEY:
+		if (mnl_attr_get_payload_len(attr) == sizeof(device->private_key)) {
+			memcpy(device->private_key, mnl_attr_get_payload(attr), sizeof(device->private_key));
+			device->flags |= WGDEVICE_HAS_PRIVATE_KEY;
+		}
+		break;
+	case WGDEVICE_A_PUBLIC_KEY:
+		if (mnl_attr_get_payload_len(attr) == sizeof(device->public_key)) {
+			memcpy(device->public_key, mnl_attr_get_payload(attr), sizeof(device->public_key));
+			device->flags |= WGDEVICE_HAS_PUBLIC_KEY;
+		}
+		break;
+	case WGDEVICE_A_LISTEN_PORT:
+		if (!mnl_attr_validate(attr, MNL_TYPE_U16))
+			device->listen_port = mnl_attr_get_u16(attr);
+		break;
+	case WGDEVICE_A_FWMARK:
+		if (!mnl_attr_validate(attr, MNL_TYPE_U32))
+			device->fwmark = mnl_attr_get_u32(attr);
+		break;
+	case WGDEVICE_A_PEERS:
+		return mnl_attr_parse_nested(attr, parse_peers, device);
+	}
+
+	return MNL_CB_OK;
+}
+
+static int read_device_cb(const struct nlmsghdr *nlh, void *data)
+{
+	return mnl_attr_parse(nlh, sizeof(struct genlmsghdr), parse_device, data);
+}
+
+static void coalesce_peers(wg_device *device)
+{
+	wg_peer *old_next_peer, *peer = device->first_peer;
+
+	while (peer && peer->next_peer) {
+		if (memcmp(peer->public_key, peer->next_peer->public_key, sizeof(wg_key))) {
+			peer = peer->next_peer;
+			continue;
+		}
+		if (!peer->first_allowedip) {
+			peer->first_allowedip = peer->next_peer->first_allowedip;
+			peer->last_allowedip = peer->next_peer->last_allowedip;
+		} else {
+			peer->last_allowedip->next_allowedip = peer->next_peer->first_allowedip;
+			peer->last_allowedip = peer->next_peer->last_allowedip;
+		}
+		old_next_peer = peer->next_peer;
+		peer->next_peer = old_next_peer->next_peer;
+		free(old_next_peer);
+	}
+}
+
+int wg_get_device(wg_device **device, const char *device_name)
+{
+	int ret = 0;
+	struct nlmsghdr *nlh;
+	struct mnlg_socket *nlg;
+
+try_again:
+	*device = calloc(1, sizeof(wg_device));
+	if (!*device)
+		return -errno;
+
+	nlg = mnlg_socket_open(WG_GENL_NAME, WG_GENL_VERSION);
+	if (!nlg) {
+		wg_free_device(*device);
+		*device = NULL;
+		return -errno;
+	}
+
+	nlh = mnlg_msg_prepare(nlg, WG_CMD_GET_DEVICE, NLM_F_REQUEST | NLM_F_ACK | NLM_F_DUMP);
+	mnl_attr_put_strz(nlh, WGDEVICE_A_IFNAME, device_name);
+	if (mnlg_socket_send(nlg, nlh) < 0) {
+		ret = -errno;
+		goto out;
+	}
+	errno = 0;
+	if (mnlg_socket_recv_run(nlg, read_device_cb, *device) < 0) {
+		ret = errno ? -errno : -EINVAL;
+		goto out;
+	}
+	coalesce_peers(*device);
+
+out:
+	if (nlg)
+		mnlg_socket_close(nlg);
+	if (ret) {
+		wg_free_device(*device);
+		if (ret == -EINTR)
+			goto try_again;
+		*device = NULL;
+	}
+	errno = -ret;
+	return ret;
+}
+
+/* first\0second\0third\0forth\0last\0\0 */
+char *wg_list_device_names(void)
+{
+	struct inflatable_buffer buffer = { .len = MNL_SOCKET_BUFFER_SIZE };
+	int ret;
+
+	ret = -ENOMEM;
+	buffer.buffer = calloc(1, buffer.len);
+	if (!buffer.buffer)
+		goto err;
+
+	ret = fetch_device_names(&buffer);
+err:
+	errno = -ret;
+	if (errno) {
+		free(buffer.buffer);
+		return NULL;
+	}
+	return buffer.buffer;
+}
+
+int wg_add_device(const char *device_name)
+{
+	return add_del_iface(device_name, true);
+}
+
+int wg_del_device(const char *device_name)
+{
+	return add_del_iface(device_name, false);
+}
+
+void wg_free_device(wg_device *dev)
+{
+	wg_peer *peer, *np;
+	wg_allowedip *allowedip, *na;
+
+	if (!dev)
+		return;
+	for (peer = dev->first_peer, np = peer ? peer->next_peer : NULL; peer; peer = np, np = peer ? peer->next_peer : NULL) {
+		for (allowedip = peer->first_allowedip, na = allowedip ? allowedip->next_allowedip : NULL; allowedip; allowedip = na, na = allowedip ? allowedip->next_allowedip : NULL)
+			free(allowedip);
+		free(peer);
+	}
+	free(dev);
+}
+
+static void encode_base64(char dest[static 4], const uint8_t src[static 3])
+{
+	const uint8_t input[] = { (src[0] >> 2) & 63, ((src[0] << 4) | (src[1] >> 4)) & 63, ((src[1] << 2) | (src[2] >> 6)) & 63, src[2] & 63 };
+	unsigned int i;
+
+	for (i = 0; i < 4; ++i)
+		dest[i] = input[i] + 'A'
+			  + (((25 - input[i]) >> 8) & 6)
+			  - (((51 - input[i]) >> 8) & 75)
+			  - (((61 - input[i]) >> 8) & 15)
+			  + (((62 - input[i]) >> 8) & 3);
+
+}
+
+void wg_key_to_base64(wg_key_b64_string base64, const wg_key key)
+{
+	unsigned int i;
+
+	for (i = 0; i < 32 / 3; ++i)
+		encode_base64(&base64[i * 4], &key[i * 3]);
+	encode_base64(&base64[i * 4], (const uint8_t[]){ key[i * 3 + 0], key[i * 3 + 1], 0 });
+	base64[sizeof(wg_key_b64_string) - 2] = '=';
+	base64[sizeof(wg_key_b64_string) - 1] = '\0';
+}
+
+static int decode_base64(const char src[static 4])
+{
+	int val = 0;
+	unsigned int i;
+
+	for (i = 0; i < 4; ++i)
+		val |= (-1
+			    + ((((('A' - 1) - src[i]) & (src[i] - ('Z' + 1))) >> 8) & (src[i] - 64))
+			    + ((((('a' - 1) - src[i]) & (src[i] - ('z' + 1))) >> 8) & (src[i] - 70))
+			    + ((((('0' - 1) - src[i]) & (src[i] - ('9' + 1))) >> 8) & (src[i] + 5))
+			    + ((((('+' - 1) - src[i]) & (src[i] - ('+' + 1))) >> 8) & 63)
+			    + ((((('/' - 1) - src[i]) & (src[i] - ('/' + 1))) >> 8) & 64)
+			) << (18 - 6 * i);
+	return val;
+}
+
+int wg_key_from_base64(wg_key key, const wg_key_b64_string base64)
+{
+	unsigned int i;
+	int val;
+	volatile uint8_t ret = 0;
+
+	if (strlen(base64) != sizeof(wg_key_b64_string) - 1 || base64[sizeof(wg_key_b64_string) - 2] != '=') {
+		errno = EINVAL;
+		goto out;
+	}
+
+	for (i = 0; i < 32 / 3; ++i) {
+		val = decode_base64(&base64[i * 4]);
+		ret |= (uint32_t)val >> 31;
+		key[i * 3 + 0] = (val >> 16) & 0xff;
+		key[i * 3 + 1] = (val >> 8) & 0xff;
+		key[i * 3 + 2] = val & 0xff;
+	}
+	val = decode_base64((const char[]){ base64[i * 4 + 0], base64[i * 4 + 1], base64[i * 4 + 2], 'A' });
+	ret |= ((uint32_t)val >> 31) | (val & 0xff);
+	key[i * 3 + 0] = (val >> 16) & 0xff;
+	key[i * 3 + 1] = (val >> 8) & 0xff;
+	errno = EINVAL & ~((ret - 1) >> 8);
+out:
+	return -errno;
+}