wireguard-lib: Import wireguard library

2 files changed, 1872 insertions, 0 deletions

diff --git a/sysdep/linux/wireguard.c b/sysdep/linux/wireguard.c
new file mode 100644
index 00000000..a7135678
--- /dev/null
+++ b/sysdep/linux/wireguard.c
@@ -0,0 +1,1775 @@
+/* SPDX-License-Identifier: LGPL-2.1+
+ *
+ * Copyright (C) 2015-2018 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
+ * Copyright (C) 2008-2012 Pablo Neira Ayuso <pablo@netfilter.org>.
+ */
+
+#define _GNU_SOURCE
+
+#include <errno.h>
+#include <linux/genetlink.h>
+#include <linux/if_link.h>
+#include <linux/netlink.h>
+#include <linux/rtnetlink.h>
+#include <netinet/in.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <time.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <assert.h>
+
+#include "wireguard.h"
+
+/* wireguard.h netlink uapi: */
+
+#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_LAST
+};
+
+enum wgallowedip_attribute {
+	WGALLOWEDIP_A_UNSPEC,
+	WGALLOWEDIP_A_FAMILY,
+	WGALLOWEDIP_A_IPADDR,
+	WGALLOWEDIP_A_CIDR_MASK,
+	__WGALLOWEDIP_A_LAST
+};
+
+/* libmnl mini library: */
+
+#define MNL_SOCKET_AUTOPID 0
+#define MNL_SOCKET_BUFFER_SIZE (sysconf(_SC_PAGESIZE) < 8192L ? sysconf(_SC_PAGESIZE) : 8192L)
+#define MNL_ALIGNTO 4
+#define MNL_ALIGN(len) (((len)+MNL_ALIGNTO-1) & ~(MNL_ALIGNTO-1))
+#define MNL_NLMSG_HDRLEN MNL_ALIGN(sizeof(struct nlmsghdr))
+#define MNL_ATTR_HDRLEN MNL_ALIGN(sizeof(struct nlattr))
+
+enum mnl_attr_data_type {
+        MNL_TYPE_UNSPEC,
+        MNL_TYPE_U8,
+        MNL_TYPE_U16,
+        MNL_TYPE_U32,
+        MNL_TYPE_U64,
+        MNL_TYPE_STRING,
+        MNL_TYPE_FLAG,
+        MNL_TYPE_MSECS,
+        MNL_TYPE_NESTED,
+        MNL_TYPE_NESTED_COMPAT,
+        MNL_TYPE_NUL_STRING,
+        MNL_TYPE_BINARY,
+        MNL_TYPE_MAX,
+};
+
+#define mnl_attr_for_each(attr, nlh, offset) \
+        for ((attr) = mnl_nlmsg_get_payload_offset((nlh), (offset)); \
+             mnl_attr_ok((attr), (char *)mnl_nlmsg_get_payload_tail(nlh) - (char *)(attr)); \
+             (attr) = mnl_attr_next(attr))
+
+#define mnl_attr_for_each_nested(attr, nest) \
+        for ((attr) = mnl_attr_get_payload(nest); \
+             mnl_attr_ok((attr), (char *)mnl_attr_get_payload(nest) + mnl_attr_get_payload_len(nest) - (char *)(attr)); \
+             (attr) = mnl_attr_next(attr))
+
+#define mnl_attr_for_each_payload(payload, payload_size) \
+        for ((attr) = (payload); \
+             mnl_attr_ok((attr), (char *)(payload) + payload_size - (char *)(attr)); \
+             (attr) = mnl_attr_next(attr))
+
+#define MNL_CB_ERROR            -1
+#define MNL_CB_STOP              0
+#define MNL_CB_OK                1
+
+typedef int (*mnl_attr_cb_t)(const struct nlattr *attr, void *data);
+typedef int (*mnl_cb_t)(const struct nlmsghdr *nlh, void *data);
+
+#ifndef MNL_ARRAY_SIZE
+#define MNL_ARRAY_SIZE(a) (sizeof(a)/sizeof((a)[0]))
+#endif
+
+static size_t mnl_nlmsg_size(size_t len)
+{
+	return len + MNL_NLMSG_HDRLEN;
+}
+
+static struct nlmsghdr *mnl_nlmsg_put_header(void *buf)
+{
+	int len = MNL_ALIGN(sizeof(struct nlmsghdr));
+	struct nlmsghdr *nlh = buf;
+
+	memset(buf, 0, len);
+	nlh->nlmsg_len = len;
+	return nlh;
+}
+
+static void *mnl_nlmsg_put_extra_header(struct nlmsghdr *nlh, size_t size)
+{
+	char *ptr = (char *)nlh + nlh->nlmsg_len;
+	size_t len = MNL_ALIGN(size);
+	nlh->nlmsg_len += len;
+	memset(ptr, 0, len);
+	return ptr;
+}
+
+static void *mnl_nlmsg_get_payload(const struct nlmsghdr *nlh)
+{
+	return (void *)nlh + MNL_NLMSG_HDRLEN;
+}
+
+static void *mnl_nlmsg_get_payload_offset(const struct nlmsghdr *nlh, size_t offset)
+{
+	return (void *)nlh + MNL_NLMSG_HDRLEN + MNL_ALIGN(offset);
+}
+
+
+static bool mnl_nlmsg_ok(const struct nlmsghdr *nlh, int len)
+{
+	return len >= (int)sizeof(struct nlmsghdr) &&
+	       nlh->nlmsg_len >= sizeof(struct nlmsghdr) &&
+	       (int)nlh->nlmsg_len <= len;
+}
+
+static struct nlmsghdr *mnl_nlmsg_next(const struct nlmsghdr *nlh, int *len)
+{
+	*len -= MNL_ALIGN(nlh->nlmsg_len);
+	return (struct nlmsghdr *)((void *)nlh + MNL_ALIGN(nlh->nlmsg_len));
+}
+
+static void *mnl_nlmsg_get_payload_tail(const struct nlmsghdr *nlh)
+{
+	return (void *)nlh + MNL_ALIGN(nlh->nlmsg_len);
+}
+
+static bool mnl_nlmsg_seq_ok(const struct nlmsghdr *nlh, unsigned int seq)
+{
+	return nlh->nlmsg_seq && seq ? nlh->nlmsg_seq == seq : true;
+}
+
+static bool mnl_nlmsg_portid_ok(const struct nlmsghdr *nlh, unsigned int portid)
+{
+	return nlh->nlmsg_pid && portid ? nlh->nlmsg_pid == portid : true;
+}
+
+static uint16_t mnl_attr_get_type(const struct nlattr *attr)
+{
+	return attr->nla_type & NLA_TYPE_MASK;
+}
+
+static uint16_t mnl_attr_get_payload_len(const struct nlattr *attr)
+{
+	return attr->nla_len - MNL_ATTR_HDRLEN;
+}
+
+static void *mnl_attr_get_payload(const struct nlattr *attr)
+{
+	return (void *)attr + MNL_ATTR_HDRLEN;
+}
+
+static bool mnl_attr_ok(const struct nlattr *attr, int len)
+{
+	return len >= (int)sizeof(struct nlattr) &&
+	       attr->nla_len >= sizeof(struct nlattr) &&
+	       (int)attr->nla_len <= len;
+}
+
+static struct nlattr *mnl_attr_next(const struct nlattr *attr)
+{
+	return (struct nlattr *)((void *)attr + MNL_ALIGN(attr->nla_len));
+}
+
+static int mnl_attr_type_valid(const struct nlattr *attr, uint16_t max)
+{
+	if (mnl_attr_get_type(attr) > max) {
+		errno = EOPNOTSUPP;
+		return -1;
+	}
+	return 1;
+}
+
+static int __mnl_attr_validate(const struct nlattr *attr,
+			       enum mnl_attr_data_type type, size_t exp_len)
+{
+	uint16_t attr_len = mnl_attr_get_payload_len(attr);
+	const char *attr_data = mnl_attr_get_payload(attr);
+
+	if (attr_len < exp_len) {
+		errno = ERANGE;
+		return -1;
+	}
+	switch(type) {
+	case MNL_TYPE_FLAG:
+		if (attr_len > 0) {
+			errno = ERANGE;
+			return -1;
+		}
+		break;
+	case MNL_TYPE_NUL_STRING:
+		if (attr_len == 0) {
+			errno = ERANGE;
+			return -1;
+		}
+		if (attr_data[attr_len-1] != '\0') {
+			errno = EINVAL;
+			return -1;
+		}
+		break;
+	case MNL_TYPE_STRING:
+		if (attr_len == 0) {
+			errno = ERANGE;
+			return -1;
+		}
+		break;
+	case MNL_TYPE_NESTED:
+
+		if (attr_len == 0)
+			break;
+
+		if (attr_len < MNL_ATTR_HDRLEN) {
+			errno = ERANGE;
+			return -1;
+		}
+		break;
+	default:
+
+		break;
+	}
+	if (exp_len && attr_len > exp_len) {
+		errno = ERANGE;
+		return -1;
+	}
+	return 0;
+}
+
+static const size_t mnl_attr_data_type_len[MNL_TYPE_MAX] = {
+	[MNL_TYPE_U8]		= sizeof(uint8_t),
+	[MNL_TYPE_U16]		= sizeof(uint16_t),
+	[MNL_TYPE_U32]		= sizeof(uint32_t),
+	[MNL_TYPE_U64]		= sizeof(uint64_t),
+	[MNL_TYPE_MSECS]	= sizeof(uint64_t),
+};
+
+static int mnl_attr_validate(const struct nlattr *attr, enum mnl_attr_data_type type)
+{
+	int exp_len;
+
+	if (type >= MNL_TYPE_MAX) {
+		errno = EINVAL;
+		return -1;
+	}
+	exp_len = mnl_attr_data_type_len[type];
+	return __mnl_attr_validate(attr, type, exp_len);
+}
+
+static int mnl_attr_parse(const struct nlmsghdr *nlh, unsigned int offset,
+			  mnl_attr_cb_t cb, void *data)
+{
+	int ret = MNL_CB_OK;
+	const struct nlattr *attr;
+
+	mnl_attr_for_each(attr, nlh, offset)
+		if ((ret = cb(attr, data)) <= MNL_CB_STOP)
+			return ret;
+	return ret;
+}
+
+static int mnl_attr_parse_nested(const struct nlattr *nested, mnl_attr_cb_t cb,
+				 void *data)
+{
+	int ret = MNL_CB_OK;
+	const struct nlattr *attr;
+
+	mnl_attr_for_each_nested(attr, nested)
+		if ((ret = cb(attr, data)) <= MNL_CB_STOP)
+			return ret;
+	return ret;
+}
+
+static uint8_t mnl_attr_get_u8(const struct nlattr *attr)
+{
+	return *((uint8_t *)mnl_attr_get_payload(attr));
+}
+
+static uint16_t mnl_attr_get_u16(const struct nlattr *attr)
+{
+	return *((uint16_t *)mnl_attr_get_payload(attr));
+}
+
+static uint32_t mnl_attr_get_u32(const struct nlattr *attr)
+{
+	return *((uint32_t *)mnl_attr_get_payload(attr));
+}
+
+
+static uint64_t mnl_attr_get_u64(const struct nlattr *attr)
+{
+	uint64_t tmp;
+	memcpy(&tmp, mnl_attr_get_payload(attr), sizeof(tmp));
+	return tmp;
+}
+
+static const char *mnl_attr_get_str(const struct nlattr *attr)
+{
+	return mnl_attr_get_payload(attr);
+}
+
+static void mnl_attr_put(struct nlmsghdr *nlh, uint16_t type, size_t len,
+			 const void *data)
+{
+	struct nlattr *attr = mnl_nlmsg_get_payload_tail(nlh);
+	uint16_t payload_len = MNL_ALIGN(sizeof(struct nlattr)) + len;
+
+	attr->nla_type = type;
+	attr->nla_len = payload_len;
+	memcpy(mnl_attr_get_payload(attr), data, len);
+	nlh->nlmsg_len += MNL_ALIGN(payload_len);
+}
+
+static void mnl_attr_put_u16(struct nlmsghdr *nlh, uint16_t type, uint16_t data)
+{
+	mnl_attr_put(nlh, type, sizeof(uint16_t), &data);
+}
+
+static void mnl_attr_put_u32(struct nlmsghdr *nlh, uint16_t type, uint32_t data)
+{
+	mnl_attr_put(nlh, type, sizeof(uint32_t), &data);
+}
+
+static void mnl_attr_put_strz(struct nlmsghdr *nlh, uint16_t type, const char *data)
+{
+	mnl_attr_put(nlh, type, strlen(data)+1, data);
+}
+
+static struct nlattr *mnl_attr_nest_start(struct nlmsghdr *nlh, uint16_t type)
+{
+	struct nlattr *start = mnl_nlmsg_get_payload_tail(nlh);
+
+	start->nla_type = NLA_F_NESTED | type;
+	nlh->nlmsg_len += MNL_ALIGN(sizeof(struct nlattr));
+	return start;
+}
+
+static bool mnl_attr_put_check(struct nlmsghdr *nlh, size_t buflen,
+			       uint16_t type, size_t len, const void *data)
+{
+	if (nlh->nlmsg_len + MNL_ATTR_HDRLEN + MNL_ALIGN(len) > buflen)
+		return false;
+	mnl_attr_put(nlh, type, len, data);
+	return true;
+}
+
+static bool mnl_attr_put_u8_check(struct nlmsghdr *nlh, size_t buflen,
+				  uint16_t type, uint8_t data)
+{
+	return mnl_attr_put_check(nlh, buflen, type, sizeof(uint8_t), &data);
+}
+
+
+static bool mnl_attr_put_u16_check(struct nlmsghdr *nlh, size_t buflen,
+				   uint16_t type, uint16_t data)
+{
+	return mnl_attr_put_check(nlh, buflen, type, sizeof(uint16_t), &data);
+}
+
+
+static bool mnl_attr_put_u32_check(struct nlmsghdr *nlh, size_t buflen,
+				   uint16_t type, uint32_t data)
+{
+	return mnl_attr_put_check(nlh, buflen, type, sizeof(uint32_t), &data);
+}
+
+static struct nlattr *mnl_attr_nest_start_check(struct nlmsghdr *nlh, size_t buflen,
+						uint16_t type)
+{
+	if (nlh->nlmsg_len + MNL_ATTR_HDRLEN > buflen)
+		return NULL;
+	return mnl_attr_nest_start(nlh, type);
+}
+
+static void mnl_attr_nest_end(struct nlmsghdr *nlh, struct nlattr *start)
+{
+	start->nla_len = mnl_nlmsg_get_payload_tail(nlh) - (void *)start;
+}
+
+static void mnl_attr_nest_cancel(struct nlmsghdr *nlh, struct nlattr *start)
+{
+	nlh->nlmsg_len -= mnl_nlmsg_get_payload_tail(nlh) - (void *)start;
+}
+
+static int mnl_cb_noop(const struct nlmsghdr *nlh, void *data)
+{
+	return MNL_CB_OK;
+}
+
+static int mnl_cb_error(const struct nlmsghdr *nlh, void *data)
+{
+	const struct nlmsgerr *err = mnl_nlmsg_get_payload(nlh);
+
+	if (nlh->nlmsg_len < mnl_nlmsg_size(sizeof(struct nlmsgerr))) {
+		errno = EBADMSG;
+		return MNL_CB_ERROR;
+	}
+
+	if (err->error < 0)
+		errno = -err->error;
+	else
+		errno = err->error;
+
+	return err->error == 0 ? MNL_CB_STOP : MNL_CB_ERROR;
+}
+
+static int mnl_cb_stop(const struct nlmsghdr *nlh, void *data)
+{
+	return MNL_CB_STOP;
+}
+
+static const mnl_cb_t default_cb_array[NLMSG_MIN_TYPE] = {
+	[NLMSG_NOOP]	= mnl_cb_noop,
+	[NLMSG_ERROR]	= mnl_cb_error,
+	[NLMSG_DONE]	= mnl_cb_stop,
+	[NLMSG_OVERRUN]	= mnl_cb_noop,
+};
+
+static int __mnl_cb_run(const void *buf, size_t numbytes,
+			unsigned int seq, unsigned int portid,
+			mnl_cb_t cb_data, void *data,
+			const mnl_cb_t *cb_ctl_array,
+			unsigned int cb_ctl_array_len)
+{
+	int ret = MNL_CB_OK, len = numbytes;
+	const struct nlmsghdr *nlh = buf;
+
+	while (mnl_nlmsg_ok(nlh, len)) {
+
+		if (!mnl_nlmsg_portid_ok(nlh, portid)) {
+			errno = ESRCH;
+			return -1;
+		}
+
+		if (!mnl_nlmsg_seq_ok(nlh, seq)) {
+			errno = EPROTO;
+			return -1;
+		}
+
+
+		if (nlh->nlmsg_flags & NLM_F_DUMP_INTR) {
+			errno = EINTR;
+			return -1;
+		}
+
+
+		if (nlh->nlmsg_type >= NLMSG_MIN_TYPE) {
+			if (cb_data){
+				ret = cb_data(nlh, data);
+				if (ret <= MNL_CB_STOP)
+					goto out;
+			}
+		} else if (nlh->nlmsg_type < cb_ctl_array_len) {
+			if (cb_ctl_array && cb_ctl_array[nlh->nlmsg_type]) {
+				ret = cb_ctl_array[nlh->nlmsg_type](nlh, data);
+				if (ret <= MNL_CB_STOP)
+					goto out;
+			}
+		} else if (default_cb_array[nlh->nlmsg_type]) {
+			ret = default_cb_array[nlh->nlmsg_type](nlh, data);
+			if (ret <= MNL_CB_STOP)
+				goto out;
+		}
+		nlh = mnl_nlmsg_next(nlh, &len);
+	}
+out:
+	return ret;
+}
+
+static int mnl_cb_run2(const void *buf, size_t numbytes, unsigned int seq,
+		       unsigned int portid, mnl_cb_t cb_data, void *data,
+		       const mnl_cb_t *cb_ctl_array, unsigned int cb_ctl_array_len)
+{
+	return __mnl_cb_run(buf, numbytes, seq, portid, cb_data, data,
+			    cb_ctl_array, cb_ctl_array_len);
+}
+
+static int mnl_cb_run(const void *buf, size_t numbytes, unsigned int seq,
+		      unsigned int portid, mnl_cb_t cb_data, void *data)
+{
+	return __mnl_cb_run(buf, numbytes, seq, portid, cb_data, data, NULL, 0);
+}
+
+struct mnl_socket {
+	int 			fd;
+	struct sockaddr_nl	addr;
+};
+
+static unsigned int mnl_socket_get_portid(const struct mnl_socket *nl)
+{
+	return nl->addr.nl_pid;
+}
+
+static struct mnl_socket *__mnl_socket_open(int bus, int flags)
+{
+	struct mnl_socket *nl;
+
+	nl = calloc(1, sizeof(struct mnl_socket));
+	if (nl == NULL)
+		return NULL;
+
+	nl->fd = socket(AF_NETLINK, SOCK_RAW | flags, bus);
+	if (nl->fd == -1) {
+		free(nl);
+		return NULL;
+	}
+
+	return nl;
+}
+
+static struct mnl_socket *mnl_socket_open(int bus)
+{
+	return __mnl_socket_open(bus, 0);
+}
+
+
+static int mnl_socket_bind(struct mnl_socket *nl, unsigned int groups, pid_t pid)
+{
+	int ret;
+	socklen_t addr_len;
+
+	nl->addr.nl_family = AF_NETLINK;
+	nl->addr.nl_groups = groups;
+	nl->addr.nl_pid = pid;
+
+	ret = bind(nl->fd, (struct sockaddr *) &nl->addr, sizeof (nl->addr));
+	if (ret < 0)
+		return ret;
+
+	addr_len = sizeof(nl->addr);
+	ret = getsockname(nl->fd, (struct sockaddr *) &nl->addr, &addr_len);
+	if (ret < 0)
+		return ret;
+
+	if (addr_len != sizeof(nl->addr)) {
+		errno = EINVAL;
+		return -1;
+	}
+	if (nl->addr.nl_family != AF_NETLINK) {
+		errno = EINVAL;
+		return -1;
+	}
+	return 0;
+}
+
+
+static ssize_t mnl_socket_sendto(const struct mnl_socket *nl, const void *buf,
+				 size_t len)
+{
+	static const struct sockaddr_nl snl = {
+		.nl_family = AF_NETLINK
+	};
+	return sendto(nl->fd, buf, len, 0,
+		      (struct sockaddr *) &snl, sizeof(snl));
+}
+
+
+static ssize_t mnl_socket_recvfrom(const struct mnl_socket *nl, void *buf,
+				   size_t bufsiz)
+{
+	ssize_t ret;
+	struct sockaddr_nl addr;
+	struct iovec iov = {
+		.iov_base	= buf,
+		.iov_len	= bufsiz,
+	};
+	struct msghdr msg = {
+		.msg_name	= &addr,
+		.msg_namelen	= sizeof(struct sockaddr_nl),
+		.msg_iov	= &iov,
+		.msg_iovlen	= 1,
+		.msg_control	= NULL,
+		.msg_controllen	= 0,
+		.msg_flags	= 0,
+	};
+	ret = recvmsg(nl->fd, &msg, 0);
+	if (ret == -1)
+		return ret;
+
+	if (msg.msg_flags & MSG_TRUNC) {
+		errno = ENOSPC;
+		return -1;
+	}
+	if (msg.msg_namelen != sizeof(struct sockaddr_nl)) {
+		errno = EINVAL;
+		return -1;
+	}
+	return ret;
+}
+
+static int mnl_socket_close(struct mnl_socket *nl)
+{
+	int ret = close(nl->fd);
+	free(nl);
+	return ret;
+}
+
+/* mnlg mini library: */
+
+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 const 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);
+}
+
+/* wireguard-specific parts: */
+
+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 void warn_unrecognized(const char *which)
+{
+	static bool once = false;
+	if (once)
+		return;
+	once = true;
+	fprintf(stderr, "Warning: one or more unrecognized %s attributes\n", which);
+}
+
+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) {
+		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;
+	size_t i, j;
+	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 (i = 0, 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, i++);
+		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 (j = 0; allowedip; allowedip = allowedip->next_allowedip) {
+				allowedip_nest = mnl_attr_nest_start_check(nlh, MNL_SOCKET_BUFFER_SIZE, j++);
+				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;
+	default:
+		warn_unrecognized("netlink");
+	}
+
+	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);
+	default:
+		warn_unrecognized("netlink");
+	}
+
+	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);
+	default:
+		warn_unrecognized("netlink");
+	}
+
+	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[4], const uint8_t src[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[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;
+
+	errno = EINVAL;
+	if (strlen(base64) != sizeof(wg_key_b64_string) - 1 || base64[sizeof(wg_key_b64_string) - 2] != '=')
+		goto out;
+
+	for (i = 0; i < 32 / 3; ++i) {
+		val = decode_base64(&base64[i * 4]);
+		if (val < 0)
+			goto out;
+		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' });
+	if (val < 0 || val & 0xff)
+		goto out;
+	key[i * 3 + 0] = (val >> 16) & 0xff;
+	key[i * 3 + 1] = (val >> 8) & 0xff;
+	errno = 0;
+out:
+	return -errno;
+}
+
+typedef int64_t fe[16];
+
+static __attribute__((noinline)) void memzero_explicit(void *s, size_t count)
+{
+	memset(s, 0, count);
+	__asm__ __volatile__("": :"r"(s) :"memory");
+}
+
+static void carry(fe o)
+{
+	int i;
+	int64_t c;
+
+	for (i = 0; i < 16; ++i) {
+		o[i] += (1LL << 16);
+		c = o[i] >> 16;
+		o[(i + 1) * (i < 15)] += c - 1 + 37 * (c - 1) * (i == 15);
+		o[i] -= c << 16;
+	}
+
+	memzero_explicit(&c, sizeof(c));
+}
+
+static void cswap(fe p, fe q, int b)
+{
+	int i;
+	int64_t t, c = ~(b - 1);
+
+	for (i = 0; i < 16; ++i) {
+		t = c & (p[i] ^ q[i]);
+		p[i] ^= t;
+		q[i] ^= t;
+	}
+
+	memzero_explicit(&t, sizeof(t));
+	memzero_explicit(&c, sizeof(c));
+	memzero_explicit(&b, sizeof(b));
+}
+
+static void pack(uint8_t *o, const fe n)
+{
+	int i, j, b;
+	fe m, t;
+
+	memcpy(t, n, sizeof(t));
+	carry(t);
+	carry(t);
+	carry(t);
+	for (j = 0; j < 2; ++j) {
+		m[0] = t[0] - 0xffed;
+		for (i = 1; i < 15; ++i) {
+			m[i] = t[i] - 0xffff - ((m[i - 1] >> 16) & 1);
+			m[i - 1] &= 0xffff;
+		}
+		m[15] = t[15] - 0x7fff - ((m[14] >> 16) & 1);
+		b = (m[15] >> 16) & 1;
+		m[14] &= 0xffff;
+		cswap(t, m, 1 - b);
+	}
+	for (i = 0; i < 16; ++i) {
+		o[2 * i] = t[i] & 0xff;
+		o[2 * i + 1] = t[i] >> 8;
+	}
+
+	memzero_explicit(m, sizeof(m));
+	memzero_explicit(t, sizeof(t));
+	memzero_explicit(&b, sizeof(b));
+}
+
+static void add(fe o, const fe a, const fe b)
+{
+	int i;
+
+	for (i = 0; i < 16; ++i)
+		o[i] = a[i] + b[i];
+}
+
+static void subtract(fe o, const fe a, const fe b)
+{
+	int i;
+
+	for (i = 0; i < 16; ++i)
+		o[i] = a[i] - b[i];
+}
+
+static void multmod(fe o, const fe a, const fe b)
+{
+	int i, j;
+	int64_t t[31] = { 0 };
+
+	for (i = 0; i < 16; ++i) {
+		for (j = 0; j < 16; ++j)
+			t[i + j] += a[i] * b[j];
+	}
+	for (i = 0; i < 15; ++i)
+		t[i] += 38 * t[i + 16];
+	memcpy(o, t, sizeof(fe));
+	carry(o);
+	carry(o);
+
+	memzero_explicit(t, sizeof(t));
+}
+
+static void invert(fe o, const fe i)
+{
+	fe c;
+	int a;
+
+	memcpy(c, i, sizeof(c));
+	for (a = 253; a >= 0; --a) {
+		multmod(c, c, c);
+		if (a != 2 && a != 4)
+			multmod(c, c, i);
+	}
+	memcpy(o, c, sizeof(fe));
+
+	memzero_explicit(c, sizeof(c));
+}
+
+static void normalize_key(uint8_t *z)
+{
+	z[31] = (z[31] & 127) | 64;
+	z[0] &= 248;
+}
+
+void wg_generate_public_key(wg_key public_key, const wg_key private_key)
+{
+	int i, r;
+	uint8_t z[32];
+	fe a = { 1 }, b = { 9 }, c = { 0 }, d = { 1 }, e, f;
+
+	memcpy(z, private_key, sizeof(z));
+	normalize_key(z);
+
+	for (i = 254; i >= 0; --i) {
+		r = (z[i >> 3] >> (i & 7)) & 1;
+		cswap(a, b, r);
+		cswap(c, d, r);
+		add(e, a, c);
+		subtract(a, a, c);
+		add(c, b, d);
+		subtract(b, b, d);
+		multmod(d, e, e);
+		multmod(f, a, a);
+		multmod(a, c, a);
+		multmod(c, b, e);
+		add(e, a, c);
+		subtract(a, a, c);
+		multmod(b, a, a);
+		subtract(c, d, f);
+		multmod(a, c, (const fe){ 0xdb41, 1 });
+		add(a, a, d);
+		multmod(c, c, a);
+		multmod(a, d, f);
+		multmod(d, b, (const fe){ 9 });
+		multmod(b, e, e);
+		cswap(a, b, r);
+		cswap(c, d, r);
+	}
+	invert(c, c);
+	multmod(a, a, c);
+	pack(public_key, a);
+
+	memzero_explicit(&r, sizeof(r));
+	memzero_explicit(z, sizeof(z));
+	memzero_explicit(a, sizeof(a));
+	memzero_explicit(b, sizeof(b));
+	memzero_explicit(c, sizeof(c));
+	memzero_explicit(d, sizeof(d));
+	memzero_explicit(e, sizeof(e));
+	memzero_explicit(f, sizeof(f));
+}
+
+void wg_generate_private_key(wg_key private_key)
+{
+	wg_generate_preshared_key(private_key);
+	normalize_key(private_key);
+}
+
+void wg_generate_preshared_key(wg_key preshared_key)
+{
+	ssize_t ret;
+	int fd;
+
+#if defined(__NR_getrandom)
+	ret = syscall(__NR_getrandom, preshared_key, sizeof(wg_key), 0);
+	if (ret == sizeof(wg_key))
+		return;
+#endif
+	fd = open("/dev/urandom", O_RDONLY);
+	assert(fd >= 0);
+	ret = read(fd, preshared_key, sizeof(wg_key));
+	close(fd);
+	assert(ret == sizeof(wg_key));
+}
diff --git a/sysdep/linux/wireguard.h b/sysdep/linux/wireguard.h
new file mode 100644
index 00000000..53d9d5d7
--- /dev/null
+++ b/sysdep/linux/wireguard.h
@@ -0,0 +1,97 @@
+/* SPDX-License-Identifier: LGPL-2.1+
+ *
+ * Copyright (C) 2015-2018 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
+ */
+
+#ifndef WIREGUARD_H
+#define WIREGUARD_H
+
+#include <net/if.h>
+#include <netinet/in.h>
+#include <sys/socket.h>
+#include <time.h>
+#include <stdint.h>
+#include <stdbool.h>
+
+typedef uint8_t wg_key[32];
+typedef char wg_key_b64_string[((sizeof(wg_key) + 2) / 3) * 4 + 1];
+
+typedef struct wg_allowedip {
+	uint16_t family;
+	union {
+		struct in_addr ip4;
+		struct in6_addr ip6;
+	};
+	uint8_t cidr;
+	struct wg_allowedip *next_allowedip;
+} wg_allowedip;
+
+enum wg_peer_flags {
+	WGPEER_REMOVE_ME = 1U << 0,
+	WGPEER_REPLACE_ALLOWEDIPS = 1U << 1,
+	WGPEER_HAS_PUBLIC_KEY = 1U << 2,
+	WGPEER_HAS_PRESHARED_KEY = 1U << 3,
+	WGPEER_HAS_PERSISTENT_KEEPALIVE_INTERVAL = 1U << 4
+};
+
+typedef struct wg_peer {
+	enum wg_peer_flags flags;
+
+	wg_key public_key;
+	wg_key preshared_key;
+
+	union {
+		struct sockaddr addr;
+		struct sockaddr_in addr4;
+		struct sockaddr_in6 addr6;
+	} endpoint;
+
+	struct timespec last_handshake_time;
+	uint64_t rx_bytes, tx_bytes;
+	uint16_t persistent_keepalive_interval;
+
+	struct wg_allowedip *first_allowedip, *last_allowedip;
+	struct wg_peer *next_peer;
+} wg_peer;
+
+enum wg_device_flags {
+	WGDEVICE_REPLACE_PEERS = 1U << 0,
+	WGDEVICE_HAS_PRIVATE_KEY = 1U << 1,
+	WGDEVICE_HAS_PUBLIC_KEY = 1U << 2,
+	WGDEVICE_HAS_LISTEN_PORT = 1U << 3,
+	WGDEVICE_HAS_FWMARK = 1U << 4
+};
+
+typedef struct wg_device {
+	char name[IFNAMSIZ];
+	uint32_t ifindex;
+
+	enum wg_device_flags flags;
+
+	wg_key public_key;
+	wg_key private_key;
+
+	uint32_t fwmark;
+	uint16_t listen_port;
+
+	struct wg_peer *first_peer, *last_peer;
+} wg_device;
+
+#define wg_for_each_device_name(__names, __name, __len) for ((__name) = (__names), (__len) = 0; ((__len) = strlen(__name)); (__name) += (__len) + 1)
+#define wg_for_each_peer(__dev, __peer) for ((__peer) = (__dev)->first_peer; (__peer); (__peer) = (__peer)->next_peer)
+#define wg_for_each_allowedip(__peer, __allowedip) for ((__allowedip) = (__peer)->first_allowedip; (__allowedip); (__allowedip) = (__allowedip)->next_allowedip)
+
+int wg_set_device(wg_device *dev);
+int wg_get_device(wg_device **dev, const char *device_name);
+int wg_add_device(const char *device_name);
+int wg_del_device(const char *device_name);
+void wg_free_device(wg_device *dev);
+char *wg_list_device_names(void); /* first\0second\0third\0forth\0last\0\0 */
+void wg_key_to_base64(wg_key_b64_string base64, const wg_key key);
+int wg_key_from_base64(wg_key key, const wg_key_b64_string base64);
+bool wg_key_is_zero(const wg_key key);
+void wg_generate_public_key(wg_key public_key, const wg_key private_key);
+void wg_generate_private_key(wg_key private_key);
+void wg_generate_preshared_key(wg_key preshared_key);
+
+#endif