contrib: add embeddable wireguard library

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

contrib/embeddable-wg-library/.gitignore

@@ -0,0 +1 @@
+test

contrib/embeddable-wg-library/Makefile

@@ -0,0 +1,7 @@
+CFLAGS += -Wall
+
+test: test.c wireguard.c wireguard.h
+
+clean:
+	rm -f test
+.PHONY: clean

contrib/embeddable-wg-library/README

@@ -0,0 +1,23 @@
+Embeddable WireGuard C Library
+==============================
+
+This is a mini single-file library, meant to be embedded directly into the
+source code of your program. It is *not* meant to be built as a shared
+library.
+
+
+Usage
+-----
+
+Copy wireguard.c and wireguard.h into your project. They should build with
+any C89 compiler. There are no dependencies except libc.
+
+Please see the set of simple functions in wireguard.h for information on
+how to use, as well as the example code in test.c.
+
+
+License
+-------
+
+Because this uses code from libmnl, wireguard.c and wireguard.h are licensed
+under the LGPL-2.1+.

contrib/embeddable-wg-library/test.c

@@ -0,0 +1,40 @@
+/* SPDX-License-Identifier: LGPL-2.1+
+ *
+ * Copyright (C) 2015-2018 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
+ */
+
+#include "wireguard.h"
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+
+int main(int argc, char *argv[])
+{
+	char *device_names, *device_name;
+	size_t len;
+
+	device_names = wg_list_device_names();
+	if (!device_names) {
+		perror("Unable to get device names");
+		return 1;
+	}
+	wg_for_each_device_name(device_names, device_name, len) {
+		wg_device *device;
+		wg_peer *peer;
+		wg_key_b64_string key;
+
+		if (wg_get_device(&device, device_name) < 0) {
+			perror("Unable to get device");
+			continue;
+		}
+		wg_key_to_base64(key, device->public_key);
+		printf("%s has public key %s\n", device_name, key);
+		wg_for_each_peer(device, peer) {
+			wg_key_to_base64(key, peer->public_key);
+			printf(" - peer %s\n", key);
+		}
+		wg_free_device(device);
+	}
+	free(device_names);
+	return 0;
+}

contrib/embeddable-wg-library/wireguard.h

@@ -0,0 +1,92 @@
+/* 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);
+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);
+
+#endif