Use multi-af tun mode on FreeBSD to make IPv6 work on tun

3 files changed, 92 insertions, 18 deletions

diff --git a/src/fastd.c b/src/fastd.c
index 2c70007..aa22cc0 100644
--- a/src/fastd.c
+++ b/src/fastd.c
@@ -246,8 +246,7 @@ void fastd_handle_receive(fastd_context_t *ctx, fastd_peer_t *peer, fastd_buffer
 			fastd_peer_eth_addr_add(ctx, peer, src_addr);
 	}
 
-	if (write(ctx->tunfd, buffer.data, buffer.len) < 0)
-		pr_warn_errno(ctx, "write");
+	fastd_tuntap_write(ctx, buffer);
 
 	if (ctx->conf->mode == MODE_TAP && ctx->conf->forward) {
 		handle_forward(ctx, peer, buffer);
@@ -477,20 +476,9 @@ static inline bool handle_tun_tap(fastd_context_t *ctx, fastd_buffer_t buffer) {
 }
 
 static void handle_tun(fastd_context_t *ctx) {
-	size_t max_len = fastd_max_packet_size(ctx);
-	fastd_buffer_t buffer = fastd_buffer_alloc(ctx, max_len, ctx->conf->min_encrypt_head_space, ctx->conf->min_encrypt_tail_space);
-
-	ssize_t len = read(ctx->tunfd, buffer.data, max_len);
-	if (len < 0) {
-		if (errno == EINTR) {
-			fastd_buffer_free(buffer);
-			return;
-		}
-
-		exit_errno(ctx, "read");
-	}
-
-	buffer.len = len;
+	fastd_buffer_t buffer = fastd_tuntap_read(ctx);
+	if (!buffer.len)
+		return;
 
 	if (handle_tun_tap(ctx, buffer))
 		return;
diff --git a/src/fastd.h b/src/fastd.h
index 8ecc141..8201c5c 100644
--- a/src/fastd.h
+++ b/src/fastd.h
@@ -340,6 +340,8 @@ void fastd_config_load_peer_dirs(fastd_context_t *ctx, fastd_config_t *conf);
 void fastd_config_handle_options(fastd_context_t *ctx, fastd_config_t *conf, int argc, char *const argv[]);
 
 void fastd_tuntap_open(fastd_context_t *ctx);
+fastd_buffer_t fastd_tuntap_read(fastd_context_t *ctx);
+void fastd_tuntap_write(fastd_context_t *ctx, fastd_buffer_t buffer);
 void fastd_tuntap_close(fastd_context_t *ctx);
 
 void fastd_cap_init(fastd_context_t *ctx);
diff --git a/src/tuntap.c b/src/tuntap.c
index e94be05..4ee1660 100644
--- a/src/tuntap.c
+++ b/src/tuntap.c
@@ -84,12 +84,35 @@ void fastd_tuntap_open(fastd_context_t *ctx) {
 	pr_debug(ctx, "tun/tap device initialized.");
 }
 
+fastd_buffer_t fastd_tuntap_read(fastd_context_t *ctx) {
+	size_t max_len = fastd_max_packet_size(ctx);
+	fastd_buffer_t buffer = fastd_buffer_alloc(ctx, max_len, ctx->conf->min_encrypt_head_space, ctx->conf->min_encrypt_tail_space);
+
+	ssize_t len = read(ctx->tunfd, buffer.data, max_len);
+	if (len < 0) {
+		if (errno == EINTR) {
+			fastd_buffer_free(buffer);
+			return (fastd_buffer_t){};
+		}
+
+		exit_errno(ctx, "read");
+	}
+
+	buffer.len = len;
+	return buffer;
+}
+
+void fastd_tuntap_write(fastd_context_t *ctx, fastd_buffer_t buffer) {
+	if (write(ctx->tunfd, buffer.data, buffer.len) < 0)
+		pr_warn_errno(ctx, "write");
+}
+
 #elif defined(__FreeBSD__)
 
 #include <net/if_tun.h>
 #include <net/if_tap.h>
 
-static void get_tap_name(fastd_context_t *ctx) {
+static void setup_tap(fastd_context_t *ctx) {
 	struct ifreq ifr = {};
 
 	if (ioctl(ctx->tunfd, TAPGIFNAME, &ifr) < 0)
@@ -99,6 +122,12 @@ static void get_tap_name(fastd_context_t *ctx) {
 	ctx->ifname = strndup(ifr.ifr_name, IFNAMSIZ-1);
 }
 
+static void setup_tun(fastd_context_t *ctx) {
+	int one = 1;
+	if (ioctl(ctx->tunfd, TUNSIFHEAD, &one) < 0)
+		exit_errno(ctx, "TUNSIFHEAD ioctl failed");
+}
+
 static void set_tap_mtu(fastd_context_t *ctx) {
 	struct tapinfo tapinfo;
 
@@ -156,7 +185,7 @@ void fastd_tuntap_open(fastd_context_t *ctx) {
 		if (strncmp(ctx->ifname, "tap", 3) != 0)
 			exit_error(ctx, "opened device doesn't to be a tap device");
 
-		get_tap_name(ctx);
+		setup_tap(ctx);
 		set_tap_mtu(ctx);
 		break;
 
@@ -164,6 +193,7 @@ void fastd_tuntap_open(fastd_context_t *ctx) {
 		if (strncmp(ctx->ifname, "tun", 3) != 0)
 			exit_error(ctx, "opened device doesn't to be a tun device");
 
+		setup_tun(ctx);
 		set_tun_mtu(ctx);
 		break;
 
@@ -174,6 +204,60 @@ void fastd_tuntap_open(fastd_context_t *ctx) {
 	pr_debug(ctx, "tun/tap device initialized.");
 }
 
+fastd_buffer_t fastd_tuntap_read(fastd_context_t *ctx) {
+	size_t max_len = fastd_max_packet_size(ctx);
+
+	fastd_buffer_t buffer;
+	if (ctx->conf->mode == MODE_TUN)
+		buffer = fastd_buffer_alloc(ctx, max_len+4, ctx->conf->min_encrypt_head_space+12, ctx->conf->min_encrypt_tail_space);
+	else
+		buffer = fastd_buffer_alloc(ctx, max_len, ctx->conf->min_encrypt_head_space, ctx->conf->min_encrypt_tail_space);
+
+	ssize_t len = read(ctx->tunfd, buffer.data, max_len);
+	if (len < 0) {
+		if (errno == EINTR) {
+			fastd_buffer_free(buffer);
+			return (fastd_buffer_t){};
+		}
+
+		exit_errno(ctx, "read");
+	}
+
+	buffer.len = len;
+
+	if (ctx->conf->mode == MODE_TUN)
+		fastd_buffer_push_head(ctx, &buffer, 4);
+
+	return buffer;
+}
+
+void fastd_tuntap_write(fastd_context_t *ctx, fastd_buffer_t buffer) {
+	if (ctx->conf->mode == MODE_TUN) {
+		uint8_t version = *((uint8_t*)buffer.data) >> 4;
+		int af;
+
+		switch (version) {
+		case 4:
+			af = AF_INET;
+			break;
+
+		case 6:
+			af = AF_INET6;
+			break;
+
+		default:
+			pr_warn(ctx, "fastd_tuntap_write: unknown IP version %u", version);
+			return;
+		}
+
+		fastd_buffer_pull_head(ctx, &buffer, 4);
+		*((uint32_t*)buffer.data) = htonl(af);
+	}
+
+	if (write(ctx->tunfd, buffer.data, buffer.len) < 0)
+		pr_warn_errno(ctx, "write");
+}
+
 #else
 
 #error unknown tun/tap implementation