From: Holger Schemel <info@artsoft.org>
Date: Wed, 1 Dec 2021 11:21:12 +0000 (+0100)
Subject: fixed receiving responses from score server
X-Git-Tag: 4.3.0.2^0
X-Git-Url: https://git.artsoft.org/?p=rocksndiamonds.git;a=commitdiff_plain;h=9695a8edd4c617065b02433dd649266e2d154ad3

fixed receiving responses from score server

This commit fixes problems with receiving (slightly) larger responses
from the score server, causing high score lists with many entries to
be cut off after a few dozen entries.

This bug was caused by misleading documentation of SDL_net function
"SDLNet_TCP_Recv()", which claims to "wait until the full requested
length is sent", which unfortunately is not correct. Instead, data
sent from the server has to be polled until everything is completely
transmitted (using the "Content-Length" field in the HTTP header).
---

diff --git a/src/libgame/http.c b/src/libgame/http.c
index cfab11fc..0064bc14 100644
--- a/src/libgame/http.c
+++ b/src/libgame/http.c
@@ -166,6 +166,103 @@ static boolean SetHTTPResponseBody(struct HttpResponse *response, char *buffer,
   return TRUE;
 }
 
+static int GetHttpResponse(TCPsocket socket, char *buffer, int max_buffer_size)
+{
+  char *buffer_ptr = buffer;
+  int buffer_left = max_buffer_size;
+  int buffer_size = 0;
+  int response_size = 0;
+
+  while (1)
+  {
+    // read as many bytes to the buffer as possible
+    int bytes = SDLNet_TCP_Recv(socket, buffer_ptr, buffer_left);
+
+    if (bytes <= 0)
+    {
+      SetHttpError("receiving response from server failed");
+
+      return -1;
+    }
+
+    buffer_ptr += bytes;
+    buffer_size += bytes;
+    buffer_left -= bytes;
+
+    // check if response size was already determined
+    if (response_size > 0)
+    {
+      // check if response data was completely received
+      if (buffer_size >= response_size)
+	break;
+
+      // continue reading response body from server
+      continue;
+    }
+
+    char *separator = "\r\n\r\n";
+    char *separator_start = strstr(buffer, separator);
+    int separator_size = strlen(separator);
+
+    // check if response header was completely received
+    if (separator_start == NULL)
+    {
+      // continue reading response header from server
+      continue;
+    }
+
+    char *content_length = "Content-Length: ";
+    char *content_length_start = strstr(buffer, content_length);
+    int head_size = separator_start - buffer;
+
+    // check if response header contains content length header
+    if (content_length_start == NULL ||
+	content_length_start >= buffer + head_size)
+    {
+      SetHttpError("receiving 'Content-Length' header from server failed");
+
+      return -1;
+    }
+
+    char *content_length_value = content_length_start + strlen(content_length);
+    char *content_length_end = strstr(content_length_value, "\r\n");
+
+    // check if content length header has line termination
+    if (content_length_end == NULL)
+    {
+      SetHttpError("receiving 'Content-Length' value from server failed");
+
+      return -1;
+    }
+
+    int value_len = content_length_end - content_length_value;
+    int max_value_len = 10;
+
+    // check if content length header has valid size
+    if (value_len > max_value_len)
+    {
+      SetHttpError("received invalid 'Content-Length' value from server");
+
+      return -1;
+    }
+
+    char value_str[value_len + 1];
+
+    strncpy(value_str, content_length_value, value_len);
+    value_str[value_len] = '\0';
+
+    int body_size = atoi(value_str);
+
+    response_size = head_size + separator_size + body_size;
+
+    // check if response data was completely received
+    if (buffer_size >= response_size)
+      break;
+  }
+
+  return buffer_size;
+}
+
 static boolean DoHttpRequestExt(struct HttpRequest *request,
 				struct HttpResponse *response,
 				char *send_buffer,
@@ -251,11 +348,11 @@ static boolean DoHttpRequestExt(struct HttpRequest *request,
     return FALSE;
   }
 
-  int recv_bytes = SDLNet_TCP_Recv(*socket, recv_buffer, max_http_buffer_size);
+  int recv_bytes = GetHttpResponse(*socket, recv_buffer, max_http_buffer_size);
 
   if (recv_bytes <= 0)
   {
-    SetHttpError("receiving response from server failed");
+    // HTTP error already set in GetHttpResponse()
 
     return FALSE;
   }