From d28b5eb2960e80d80e967a3f01ce70e1fa457808 Mon Sep 17 00:00:00 2001
From: cbdev <cb@cbcdn.com>
Date: Fri, 17 May 2019 19:41:14 +0200
Subject: Split out websocket handling, HTTP header processing

---
 ws_proto.c | 213 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 213 insertions(+)
 create mode 100644 ws_proto.c

(limited to 'ws_proto.c')

diff --git a/ws_proto.c b/ws_proto.c
new file mode 100644
index 0000000..b9f92e9
--- /dev/null
+++ b/ws_proto.c
@@ -0,0 +1,213 @@
+#include <ctype.h>
+
+static size_t socks = 0;
+static websocket* sock = NULL;
+
+int ws_close(websocket* ws){
+	size_t p;
+
+	if(ws->fd >= 0){
+		close(ws->fd);
+		ws->fd = -1;
+	}
+
+	if(ws->peer >= 0){
+		close(ws->peer);
+		ws->peer = -1;
+	}
+
+	for(p = 0; p < ws->protocols; p++){
+		free(ws->protocol[p]);
+	}
+	ws->protocols = 0;
+	ws->protocol = NULL;
+
+	ws->read_buffer_offset = 0;
+
+	free(ws->request_path);
+	ws->request_path = NULL;
+
+	free(ws->socket_key);
+	ws->socket_key = NULL;
+
+	ws->websocket_version = 0;
+	ws->want_upgrade = 0;
+
+	return 0;
+}
+
+int ws_accept(int listen_fd){
+	size_t n = 0;
+
+	websocket ws = {
+		.fd = accept(listen_fd, NULL, NULL),
+		.peer = -1
+	};
+
+	//try to find a slot to occupy
+	for(n = 0; n < socks; n++){
+		if(sock[n].fd == -1){
+			break;
+		}
+	}
+
+	//none found, need to extend
+	if(n == socks){
+		sock = realloc(sock, (socks + 1) * sizeof(websocket));
+		if(!sock){
+			close(ws.fd);
+			fprintf(stderr, "Failed to allocate memory\n");
+			return 1;
+		}
+		socks++;
+	}
+
+	sock[n] = ws;
+
+	return 0;
+}
+
+int ws_handle_new(websocket* ws){
+	size_t u;
+	char* path, *proto;
+
+	if(!strncmp((char*) ws->read_buffer, "GET ", 4)){
+		path = (char*) ws->read_buffer + 4;
+		for(u = 0; path[u] && !isspace(path[u]); u++){
+		}
+		path[u] = 0;
+		proto = path + u + 1;
+	}
+	//TODO handle other methods
+	else{
+		fprintf(stderr, "Unknown HTTP method in request\n");
+		return 1;
+	}
+
+	if(strncmp(proto, "HTTP/", 5)){
+		fprintf(stderr, "Malformed HTTP initiation\n");
+		return 1;
+	}
+
+	ws->state = ws_http;
+	ws->request_path = strdup(path);
+	return 0;
+}
+
+int ws_upgrade_http(websocket* ws){
+	if(ws->websocket_version == 13
+			&& ws->want_upgrade){
+
+		return 0;
+	}
+	return 1;
+}
+
+int ws_handle_http(websocket* ws){
+	char* header, *value;
+	if(!ws->read_buffer[0]){
+		return ws_upgrade_http(ws);
+	}
+	else if(isspace(ws->read_buffer[0])){
+		//i hate header folding
+		//TODO disconnect client
+		return 1;
+	}
+	else{
+		header = (char*) ws->read_buffer;
+		value = strchr(header, ':');
+		if(!value){
+			//TODO disconnect
+			return 1;
+		}
+		*value = 0;
+		value++;
+		for(; isspace(*value); value++){
+		}
+	}
+
+	if(!strcmp(header, "Sec-WebSocket-Version")){
+		ws->websocket_version = strtoul(value, NULL, 10);
+	}
+	else if(!strcmp(header, "Sec-WebSocket-Key")){
+		ws->socket_key = strdup(value);
+	}
+	else if(!strcmp(header, "Upgrade") && !strcmp(value, "websocket")){
+		ws->want_upgrade = 1;
+	}
+	//TODO parse websocket protocol offers
+	return 0;
+}
+
+int ws_data(websocket* ws){
+	ssize_t bytes_read, u, bytes_left = sizeof(ws->read_buffer) - ws->read_buffer_offset;
+	int rv = 0;
+
+	bytes_read = recv(ws->fd, ws->read_buffer + ws->read_buffer_offset, bytes_left - 1, 0);
+	if(bytes_read < 0){
+		fprintf(stderr, "Failed to receive from websocket: %s\n", strerror(errno));
+		ws_close(ws);
+		return 0;
+	}
+	else if(bytes_read == 0){
+		//client closed connection
+		ws_close(ws);
+		return 0;
+	}
+
+	//terminate new data
+	ws->read_buffer[ws->read_buffer_offset + bytes_read] = 0;
+	
+	switch(ws->state){
+		case ws_new:
+		case ws_http:
+			//scan for newline, handle line
+			for(u = 0; u < bytes_read - 1; u++){
+				if(!strncmp((char*) ws->read_buffer + ws->read_buffer_offset + u, "\r\n", 2)){
+					//terminate line
+					ws->read_buffer[ws->read_buffer_offset + u] = 0;
+
+					if(ws->state == ws_new){
+						rv |= ws_handle_new(ws);
+					}
+					else{
+						rv |= ws_handle_http(ws);
+					}
+					//TODO handle rv
+
+					//remove from buffer
+					bytes_read -= (u + 2);
+					memmove(ws->read_buffer, ws->read_buffer + ws->read_buffer_offset + u + 2, bytes_read);
+					ws->read_buffer_offset = 0;
+
+					//restart from the beginning
+					u = -1;
+				}
+			}
+			break;
+		//case ws_rfc6455:
+			//TODO parse websocket encap, forward to peer
+	}
+
+	//update read buffer offset
+	ws->read_buffer_offset = bytes_read;
+
+	//disconnect spammy clients
+	if(sizeof(ws->read_buffer) - ws->read_buffer_offset < 2){
+		fprintf(stderr, "Disconnecting misbehaving client\n");
+		ws_close(ws);
+		return 0;
+	}
+	return rv;
+}
+
+void ws_cleanup(){
+	size_t n;
+	for(n = 0; n < socks; n++){
+		ws_close(sock + n);
+	}
+
+	free(sock);
+	sock = NULL;
+	socks = 0;
+}
-- 
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