[tor/master] Respond meaningfully to HTTP requests on the control port. Fix #1667

5 Jul 2017

commit 417d778652770a8f4b0b6f8e5d8e139e193b8b1e
Author: Ravi Chandra Padmala <neenaoffline@gmail.com>
Date:   Tue Feb 21 08:52:03 2012 +0530

    Respond meaningfully to HTTP requests on the control port. Fix #1667
    
      (Squashed with bufferevents portions removed, by nickm)
---
 changes/bug1667  |  4 ++++
 src/or/buffers.c | 25 +++++++++++++++++++++++++
 src/or/buffers.h |  2 ++
 src/or/control.c | 38 ++++++++++++++++++++++++++++++++++++++
 4 files changed, 69 insertions(+)

diff --git a/changes/bug1667 b/changes/bug1667
new file mode 100644
index 0000000..195993d
--- /dev/null
+++ b/changes/bug1667
@@ -0,0 +1,4 @@
+  o Minor features:
+    - If the control port is used as the HTTP proxy, responds with
+      a meaningful "This is the Tor control port" message, and logs
+      the event. Fixes bug 1667.
diff --git a/src/or/buffers.c b/src/or/buffers.c
index 3692ed4..af1b67e 100644
--- a/src/or/buffers.c
+++ b/src/or/buffers.c
@@ -2022,6 +2022,31 @@ parse_socks_client(const uint8_t *data, size_t datalen,
   return -1;
 }
 
+/** Return true if <b>cmd</b> looks like a HTTP (proxy) request. */
+int
+peek_buf_has_http_command(buf_t *buf)
+{
+  if (peek_buf_startswith(buf, "CONNECT ") ||
+      peek_buf_startswith(buf, "DELETE ") ||
+      peek_buf_startswith(buf, "GET ") ||
+      peek_buf_startswith(buf, "POST ") ||
+      peek_buf_startswith(buf, "PUT " ))
+    return 1;
+  return 0;
+}
+
+/** Return 1 iff <b>buf</b> starts with <b>cmd</b>. <b>cmd</b> must be a null
+ * terminated string */
+int
+peek_buf_startswith(buf_t *buf, const char *cmd)
+{
+  int clen = strlen(cmd);
+  if (buf->datalen >= clen)
+    if (!strncasecmp((buf->head)->data, cmd, (size_t) clen))
+      return 1;
+  return 0;
+}
+
 /** Return 1 iff buf looks more like it has an (obsolete) v0 controller
  * command on it than any valid v1 controller command. */
 int
diff --git a/src/or/buffers.h b/src/or/buffers.h
index 23b58a5..5650bea 100644
--- a/src/or/buffers.h
+++ b/src/or/buffers.h
@@ -53,6 +53,8 @@ int fetch_from_buf_socks_client(buf_t *buf, int state, char **reason);
 int fetch_from_buf_line(buf_t *buf, char *data_out, size_t *data_len);
 
 int peek_buf_has_control0_command(buf_t *buf);
+int peek_buf_startswith(buf_t *buf, const char *cmd);
+int peek_buf_has_http_command(buf_t *buf);
 
 int fetch_ext_or_command_from_buf(buf_t *buf, ext_or_cmd_t **out);
 
diff --git a/src/or/control.c b/src/or/control.c
index 9454a7a..3e31f17 100644
--- a/src/or/control.c
+++ b/src/or/control.c
@@ -4882,6 +4882,12 @@ peek_connection_has_control0_command(connection_t *conn)
   return peek_buf_has_control0_command(conn->inbuf);
 }
 
+static int
+peek_connection_has_http_command(connection_t *conn)
+{
+  return peek_buf_has_http_command(conn->inbuf);
+}
+
 /** Called when data has arrived on a v1 control connection: Try to fetch
  * commands from conn->inbuf, and execute them.
  */
@@ -4921,6 +4927,38 @@ connection_control_process_inbuf(control_connection_t *conn)
     return 0;
   }
 
+  /* If the user has the HTTP proxy port and the control port confused. */
+  if (conn->_base.state == CONTROL_CONN_STATE_NEEDAUTH &&
+      peek_connection_has_http_command(TO_CONN(conn))) {
+    connection_write_str_to_buf("HTTP/1.0 501 Tor ControlPort is not a proxy"
+"\r\nContent-Type: text/html; charset=iso-8859-1\r\n\r\n"
+"<html>\n"
+"<head>\n"
+"<title>Tor's ControlPort is not proxy</title>\n"
+"</head>\n"
+"<body>\n"
+"<h1>Tor's ControlPort is not a proxy</h1>\n"
+"<p>\n"
+"It appears you have configured your web browser to use Tor's control port"
+" as an HTTP proxy.\n"
+"This is not correct: Tor's default SOCKS proxy port is 9050.\n"
+"Please configure your client accordingly.\n"
+"</p>\n"
+"<p>\n"
+"See <a href=\"https://www.torproject.org/documentation.html\">"
+           "https://www.torproject.org/documentation.html</a> for more "
+           "information.\n"
+"<!-- Plus this comment, to make the body response more than 512 bytes, so "
+"     IE will be willing to display it. Comment comment comment comment "
+"     comment comment comment comment comment comment comment comment.-->\n"
+"</p>\n"
+"</body>\n"
+"</html>\n", conn);
+    log_notice(LD_CONTROL, "Received HTTP request on ControlPort");
+    connection_mark_and_flush(TO_CONN(conn));
+    return 0;
+  }
+
  again:
   while (1) {
     size_t last_idx;

    

nickm＠torproject.org

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