From 3187fdef5ba7a13b576324e541d28a43006f31d1 Mon Sep 17 00:00:00 2001
From: Simon Rettberg
Date: Thu, 26 Oct 2017 23:34:07 +0200
Subject: [SERVER] net: Simplify check for HTTP

Pretty loose guesswork, but preventing the false positives
would not lead to any meaningful result anyways, so why bother.
---
 src/server/net.c | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/src/server/net.c b/src/server/net.c
index 79d6cfa..c7d34de 100644
--- a/src/server/net.c
+++ b/src/server/net.c
@@ -170,23 +170,24 @@ void* net_handleNewConnection(void *clientPtr)
 	sock_setTimeout( client->sock, _clientTimeout );
 	do {
 		const int ret = (int)recv( client->sock, &request, sizeof(request), MSG_WAITALL );
-		// Let's see if this looks like an HTTP request
-		if ( ret > 5 && request.magic != dnbd3_packet_magic
-				&& ( strncmp( (char*)&request, "GET ", 4 ) == 0 || strncmp( (char*)&request, "POST ", 5 ) == 0 ) ) {
-			rpc_sendStatsJson( client->sock, &client->host, &request, ret );
-			goto fail_preadd;
-		}
-
 		// It's expected to be a real dnbd3 client
-		// Check request for validity
-		if ( ret != sizeof(request) ) {
+		// Check request for validity. This implicitly dictates that all HTTP requests are more than 16 bytes...
+		if ( ret != (int)sizeof(request) ) {
 			logadd( LOG_DEBUG1, "Error receiving request: Could not read message header (%d/%d, e=%d)", (int)ret, (int)sizeof(request), errno );
 			goto fail_preadd;
 		}
+
 		if ( request.magic != dnbd3_packet_magic ) {
-			logadd( LOG_DEBUG1, "Magic in client handshake incorrect" );
+			// Let's see if this looks like an HTTP request
+			if ( ((char*)&request)[0] == 'G' || ((char*)&request)[0] == 'P' ) {
+				// Close enough...
+				rpc_sendStatsJson( client->sock, &client->host, &request, ret );
+			} else {
+				logadd( LOG_DEBUG1, "Magic in client handshake incorrect" );
+			}
 			goto fail_preadd;
 		}
+		// Magic OK, untangle byte order if required
 		fixup_request( request );
 		if ( request.cmd != CMD_SELECT_IMAGE ) {
 			logadd( LOG_WARNING, "Client sent != CMD_SELECT_IMAGE in handshake (got cmd=%d, size=%d), dropping client.", (int)request.cmd, (int)request.size );
-- 
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