From 79e063d6aa6116231fdfb374f52507236ca3770e Mon Sep 17 00:00:00 2001
From: cbdev <cb@cbcdn.com>
Date: Sat, 25 May 2019 09:10:55 +0200
Subject: Basic forwarding and builtin extension functions

---
 builtins.c | 140 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 132 insertions(+), 8 deletions(-)

(limited to 'builtins.c')

diff --git a/builtins.c b/builtins.c
index b75dcd0..fa73260 100644
--- a/builtins.c
+++ b/builtins.c
@@ -1,26 +1,150 @@
-static ws_peer_info default_peer = {
-	.transport = peer_tcp_client,
-	.host = "localhost",
-	.port = "5900"
-};
+#define UTF8_BYTE(a) ((a & 0xC0) == 0x80)
 
-//TODO backend configuration
+/*
+ * The defaultpeer backend returns the same peer configured peer for any
+ * incoming connection. This may be useful for testing or for configurations
+ * where there is just one peer anyway.
+ */
+
+/* Global data storage for the backend */
+static ws_peer_info default_peer = {0};
+static char* default_peer_proto = NULL;
+
+/* 
+ * Initialization function for the defaultpeer backend
+ * Heap-allocate all data so it can be safely free'd at cleanup
+ */
+uint64_t backend_defaultpeer_init(){
+	ws_peer_info startup_peer = {
+		.transport = peer_tcp_client,
+		.host = strdup("localhost"),
+		.port = strdup("5900")
+	};
+
+	default_peer = startup_peer;
+	return WEBSOCKSY_API_VERSION;
+}
+
+/*
+ * Configuration function for the defaultpeer backend
+ */
+uint64_t backend_defaultpeer_configure(char* key, char* value){
+	if(!strcmp(key, "host")){
+		//TODO extract peer protocol
+		free(default_peer.host);
+		default_peer.host = strdup(value);
+	}
+	else if(!strcmp(key, "port")){
+		free(default_peer.port);
+		default_peer.port = strdup(value);
+	}
+	else if(!strcmp(key, "protocol")){
+		free(default_peer_proto);
+		default_peer_proto = strdup(value);
+	}
+	return 1;
+}
+
+/*
+ * defaultpeer backend core
+ * Returns the configured default peer for any incoming request and selects either
+ * a matching or no subprotocol.
+ */
 ws_peer_info backend_defaultpeer_query(char* endpoint, size_t protocols, char** protocol, size_t headers, ws_http_header* header, websocket* ws){
+	size_t p;
 	//return a copy of the default peer
 	ws_peer_info peer = default_peer;
 	peer.host = (default_peer.host) ? strdup(default_peer.host) : NULL;
 	peer.port = (default_peer.port) ? strdup(default_peer.port) : NULL;
 
-	//TODO backend protocol discovery
+	//if none set, announce none
 	peer.protocol = protocols;
+
+	if(default_peer_proto){
+		for(p = 0; p < protocols; p++){
+			if(!strcasecmp(protocol[p], default_peer_proto)){
+				peer.protocol = p;
+				break;
+			}
+		}
+
+		//if any, return first
+		if(!strcmp(default_peer_proto, "*")){
+			peer.protocol = 0;
+		}
+	}
 	return peer;
 }
 
+/*
+ * Cleanup function for the defaultpeer backend.
+ * Frees all allocated data.
+ */
+void backend_defaultpeer_cleanup(){
+	free(default_peer.host);
+	default_peer.host = NULL;
+	free(default_peer.port);
+	default_peer.port = NULL;
+	free(default_peer_proto);
+	default_peer_proto = NULL;
+}
+
+/*
+ * The `auto` stream framing function forwards all incoming data from the peer immediately,
+ * with the text frame type if the data is valid UTF8 and the binary frame type otherwise.
+ */
 int64_t framing_auto(uint8_t* data, size_t length, size_t last_read, ws_operation* opcode, void** framing_data, char* config){
-	//TODO implement auto framer
+	size_t p;
+	uint8_t valid = 1;
+	for(p = 0; p < length; p++){
+		//4-byte codepoint
+		if((data[p] & 0xF8) == 0xF0){
+			if((p + 3) >= length
+					|| !UTF8_BYTE(data[p + 1])
+					|| !UTF8_BYTE(data[p + 2])
+					|| !UTF8_BYTE(data[p + 3])){
+				valid = 0;
+				break;
+			}
+			p += 3;
+		}
+		//3 byte codepoint
+		else if((data[p] & 0xF0) == 0xE0){
+			if((p + 2) >= length
+					|| !UTF8_BYTE(data[p + 1])
+					|| !UTF8_BYTE(data[p + 2])){
+				valid = 0;
+				break;
+			}
+			p += 2;
+		}
+		//2 byte codepoint
+		else if((data[p] & 0xE0) == 0xC0){
+			if((p + 1) >= length
+					|| !UTF8_BYTE(data[p + 1])){
+				valid = 0;
+				break;
+			}
+			p++;
+		}
+		//not a 1 byte codepoint -> not utf8
+		else if(data[p] & 0x80){
+			valid = 0;
+			break;
+		}
+	}
+
+	//if valid utf8, send as text frame
+	if(valid){
+		*opcode = ws_frame_text;
+	}
+
 	return length;
 }
 
+/*
+ * The `binary` peer stream framing function forwards all incoming data from the peer immediately as binary frames
+ */
 int64_t framing_binary(uint8_t* data, size_t length, size_t last_read, ws_operation* opcode, void** framing_data, char* config){
 	return length;
 }
-- 
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