From: Guus Sliepen <guus@meshlink.io>
Date: Tue, 22 Jun 2021 19:44:01 +0000 (+0200)
Subject: Handle raw packets from tiny peers.
X-Git-Url: https://git.meshlink.io/?a=commitdiff_plain;h=b3d36651004e8124d9410e249215997a108473ec;p=meshlink

Handle raw packets from tiny peers.

Tiny peers don't support UTCP channels, but send raw packets directly over
the meta connection.
---

diff --git a/src/connection.h b/src/connection.h
index 68d9e971..5e3a7ac7 100644
--- a/src/connection.h
+++ b/src/connection.h
@@ -41,6 +41,7 @@ typedef struct connection_status_t {
 	uint16_t invitation: 1;             /* 1 if this is an invitation */
 	uint16_t invitation_used: 1;        /* 1 if the invitation has been consumed */
 	uint16_t initiator: 1;              /* 1 if we initiated this connection */
+	uint16_t raw_packet: 1;             /* 1 if we are expecting a raw packet next */
 } connection_status_t;
 
 #include "ecdsa.h"
diff --git a/src/meshlink.c b/src/meshlink.c
index 4cc285de..f153f757 100644
--- a/src/meshlink.c
+++ b/src/meshlink.c
@@ -4034,7 +4034,7 @@ void meshlink_set_channel_receive_cb(meshlink_handle_t *mesh, meshlink_channel_t
 	channel->receive_cb = cb;
 }
 
-static void channel_receive(meshlink_handle_t *mesh, meshlink_node_t *source, const void *data, size_t len) {
+void channel_receive(meshlink_handle_t *mesh, meshlink_node_t *source, const void *data, size_t len) {
 	(void)mesh;
 	node_t *n = (node_t *)source;
 
@@ -4188,7 +4188,6 @@ void meshlink_set_channel_accept_cb(meshlink_handle_t *mesh, meshlink_channel_ac
 	}
 
 	mesh->channel_accept_cb = cb;
-	mesh->receive_cb = channel_receive;
 
 	for splay_each(node_t, n, mesh->nodes) {
 		if(!n->utcp && n != mesh->self) {
@@ -4283,7 +4282,6 @@ meshlink_channel_t *meshlink_channel_open_ex(meshlink_handle_t *mesh, meshlink_n
 		n->utcp = utcp_init(channel_accept, channel_pre_accept, channel_send, n);
 		utcp_set_mtu(n->utcp, n->mtu - sizeof(meshlink_packethdr_t));
 		utcp_set_retransmit_cb(n->utcp, channel_retransmit);
-		mesh->receive_cb = channel_receive;
 
 		if(!n->utcp) {
 			meshlink_errno = errno == ENOMEM ? MESHLINK_ENOMEM : MESHLINK_EINTERNAL;
diff --git a/src/meshlink_internal.h b/src/meshlink_internal.h
index 26186015..469a05b1 100644
--- a/src/meshlink_internal.h
+++ b/src/meshlink_internal.h
@@ -250,6 +250,7 @@ extern meshlink_log_cb_t global_log_cb;
 void handle_duplicate_node(meshlink_handle_t *mesh, struct node_t *n);
 void handle_network_change(meshlink_handle_t *mesh, bool online);
 void call_error_cb(meshlink_handle_t *mesh, meshlink_errno_t meshlink_errno);
+void channel_receive(meshlink_handle_t *mesh, meshlink_node_t *node, const void *data, size_t len);
 
 /// Per-instance PRNG
 static inline int prng(meshlink_handle_t *mesh, uint64_t max) {
diff --git a/src/meta.c b/src/meta.c
index 13024677..a023d2a5 100644
--- a/src/meta.c
+++ b/src/meta.c
@@ -47,7 +47,7 @@ bool send_meta_sptps(void *handle, uint8_t type, const void *buffer, size_t leng
 bool send_meta(meshlink_handle_t *mesh, connection_t *c, const char *buffer, int length) {
 	assert(c);
 	assert(buffer);
-	assert(length);
+	assert(length >= 0);
 
 	logger(mesh, MESHLINK_DEBUG, "Sending %d bytes of metadata to %s", length, c->name);
 
@@ -107,10 +107,16 @@ bool receive_meta_sptps(void *handle, uint8_t type, const void *data, uint16_t l
 		return true;
 	}
 
-	/* Are we receiving a TCPpacket? */
+	/* Are we receiving a raw packet? */
+
+	if(c->status.raw_packet) {
+		c->status.raw_packet = false;
 
-	if(c->tcplen) {
-		abort(); // TODO: get rid of tcplen altogether
+		if(mesh->receive_cb) {
+			mesh->receive_cb(mesh, (meshlink_node_t *)c->node, data, length);
+		}
+
+		return true;
 	}
 
 	/* Change newline to null byte, just like non-SPTPS requests */
diff --git a/src/net_packet.c b/src/net_packet.c
index 02a617d1..67fadfc5 100644
--- a/src/net_packet.c
+++ b/src/net_packet.c
@@ -279,6 +279,11 @@ static void send_sptps_packet(meshlink_handle_t *mesh, node_t *n, vpn_packet_t *
 	}
 
 	if(!n->status.validkey) {
+		if(n->connection && (n->connection->flags & PROTOCOL_TINY) & n->connection->status.active) {
+			send_raw_packet(mesh, n->connection, origpkt);
+			return;
+		}
+
 		logger(mesh, MESHLINK_INFO, "No valid key known yet for %s", n->name);
 
 		if(!n->status.waitingforkey) {
diff --git a/src/protocol.c b/src/protocol.c
index 9d1dff97..9975402c 100644
--- a/src/protocol.c
+++ b/src/protocol.c
@@ -44,6 +44,7 @@ static bool (*request_handlers[NUM_REQUESTS])(meshlink_handle_t *, connection_t
 	[KEY_CHANGED] = key_changed_h,
 	[REQ_KEY] = req_key_h,
 	[ANS_KEY] = ans_key_h,
+	[PACKET] = raw_packet_h,
 };
 
 /* Request names */
@@ -61,6 +62,7 @@ static const char *request_name[NUM_REQUESTS] = {
 	[KEY_CHANGED] = "KEY_CHANGED",
 	[REQ_KEY] = "REQ_KEY",
 	[ANS_KEY] = "ANS_KEY",
+	[PACKET] = "PACKET",
 };
 
 bool check_id(const char *id) {
diff --git a/src/protocol.h b/src/protocol.h
index 05c2203b..94f760f1 100644
--- a/src/protocol.h
+++ b/src/protocol.h
@@ -100,6 +100,7 @@ bool send_add_edge(struct meshlink_handle *mesh, struct connection_t *, const st
 bool send_del_edge(struct meshlink_handle *mesh, struct connection_t *, const struct edge_t *, int contradictions);
 bool send_req_key(struct meshlink_handle *mesh, struct node_t *);
 bool send_canonical_address(struct meshlink_handle *mesh, struct node_t *);
+bool send_raw_packet(struct meshlink_handle *mesh, struct connection_t *, const vpn_packet_t *);
 
 /* Request handlers  */
 
@@ -116,5 +117,6 @@ bool key_changed_h(struct meshlink_handle *mesh, struct connection_t *, const ch
 bool req_key_h(struct meshlink_handle *mesh, struct connection_t *, const char *);
 bool ans_key_h(struct meshlink_handle *mesh, struct connection_t *, const char *);
 bool tcppacket_h(struct meshlink_handle *mesh, struct connection_t *, const char *);
+bool raw_packet_h(struct meshlink_handle *mesh, struct connection_t *, const char *);
 
 #endif
diff --git a/src/protocol_misc.c b/src/protocol_misc.c
index 7410ad13..65895437 100644
--- a/src/protocol_misc.c
+++ b/src/protocol_misc.c
@@ -145,3 +145,16 @@ bool tcppacket_h(meshlink_handle_t *mesh, connection_t *c, const char *request)
 	// This should never happen with MeshLink.
 	return false;
 }
+
+bool send_raw_packet(meshlink_handle_t *mesh, connection_t *c, const vpn_packet_t *packet) {
+	size_t hdrsize = sizeof(meshlink_packethdr_t);
+	assert(packet->len >= hdrsize);
+	return send_request(mesh, c, NULL, "%d", PACKET) && send_meta(mesh, c, (const char *)packet->data + hdrsize, packet->len - hdrsize);
+}
+
+bool raw_packet_h(meshlink_handle_t *mesh, connection_t *c, const char *request) {
+	(void)mesh;
+	(void)request;
+	c->status.raw_packet = true;
+	return true;
+}
diff --git a/src/route.c b/src/route.c
index ee36a9bf..ea3a5434 100644
--- a/src/route.c
+++ b/src/route.c
@@ -69,7 +69,9 @@ void route(meshlink_handle_t *mesh, node_t *source, vpn_packet_t *packet) {
 
 		logger(mesh, MESHLINK_DEBUG, "I received a packet for me with payload: %s\n", hex);
 
-		if(mesh->receive_cb) {
+		if(source->utcp) {
+			channel_receive(mesh, (meshlink_node_t *)source, payload, len);
+		} else if(mesh->receive_cb) {
 			mesh->receive_cb(mesh, (meshlink_node_t *)source, payload, len);
 		}