Simplify initial handshaking

src/stream_engine.cpp

@@ -59,7 +59,6 @@ zmq::stream_engine_t::stream_engine_t (fd_t fd_, const options_t &options_, cons
     encoder (NULL),
     handshaking (true),
     greeting_bytes_read (0),
-    greeting_size (0),
     session (NULL),
     options (options_),
     endpoint (endpoint_),
@@ -132,13 +131,6 @@ void zmq::stream_engine_t::plug (io_thread_t *io_thread_,
     io_object_t::plug (io_thread_);
     handle = add_fd (s);
 
-    //  We need to detect whether our peer is using the versioned
-    //  protocol. The detection is done in two steps. First, we read
-    //  first two bytes and check if the long format of length is in use.
-    //  If so, we receive and check the 'flags' field. If the rightmost bit
-    //  is 1, the peer is using versioned protocol.
-    greeting_size = 2;
-
     //  Send the 'length' and 'flags' fields of the identity message.
     //  The 'length' field is encoded in the long format.
     outpos = greeting_output_buffer;
@@ -311,90 +303,52 @@ void zmq::stream_engine_t::activate_in ()
     in_event ();
 }
 
-int zmq::stream_engine_t::receive_greeting ()
+bool zmq::stream_engine_t::handshake ()
 {
+    zmq_assert (handshaking);
     zmq_assert (greeting_bytes_read < greeting_size);
 
+    //  Receive the greeting.
     while (greeting_bytes_read < greeting_size) {
         const int n = read (greeting + greeting_bytes_read,
                             greeting_size - greeting_bytes_read);
-        if (n == -1)
-            return -1;
+        if (n == -1) {
+            error ();
+            return false;
+        }
+
         if (n == 0)
-            return 0;
+            return false;
 
         greeting_bytes_read += n;
 
-        if (greeting_bytes_read < greeting_size)
-            continue;
-
-        if (greeting_size == 2) {
-            //  We have received the first two bytes from the peer.
+        //  We have received at least one byte from the peer.
         //  If the first byte is not 0xff, we know that the
         //  peer is using unversioned protocol.
         if (greeting [0] != 0xff)
             break;
 
-            //  This may still be a long identity message (either
-            //  254 or 255 bytes long). We need to receive 8 more
-            //  bytes so we can inspect the potential 'flags' field.
-            greeting_size = 10;
-        }
-        else
-        if (greeting_size == 10) {
-            //  Inspect the rightmost bit of the 10th byte (which coincides
+        if (greeting_bytes_read < 10)
+            continue;
+
+        //  Inspect the right-most bit of the 10th byte (which coincides
         //  with the 'flags' field if a regular message was sent).
         //  Zero indicates this is a header of identity message
         //  (i.e. the peer is using the unversioned protocol).
         if (!(greeting [9] & 0x01))
             break;
 
-            //  This is truly a handshake and we can now send the rest of
-            //  the greeting message out.
-
+        //  The peer is using versioned protocol.
+        //  Send the rest of the greeting, if necessary.
+        if (outpos + outsize != greeting_output_buffer + greeting_size) {
             if (outsize == 0)
                 set_pollout (handle);
-
-            zmq_assert (outpos != NULL);
-
             outpos [outsize++] = 1;             // Protocol version
-            outpos [outsize++] = 1; // Remaining length (1 byte for v1)
             outpos [outsize++] = options.type;  // Socket type
-
-            //  Read the 'version' and 'remaining_length' fields.
-            greeting_size = 12;
-        }
-        else
-        if (greeting_size == 12) {
-            //  We have received the greeting message up to
-            //  the 'remaining_length' field. Receive the remaining
-            //  bytes of the greeting.
-            greeting_size += greeting [11];
         }
     }
 
-    return 0;
-}
-
-bool zmq::stream_engine_t::handshake ()
-{
-    zmq_assert (handshaking);
-    zmq_assert (greeting_bytes_read < greeting_size);
-
-    int rc = receive_greeting ();
-    if (rc == -1) {
-        error ();
-        return false;
-    }
-
-    if (greeting_bytes_read < greeting_size)
-        return false;
-
-    //  We have received either a header of identity message
-    //  or the whole greeting.
-    zmq_assert (greeting [0] != 0xff || greeting_bytes_read >= 10);
-
-    //  POsition of the version field in the greeting.
+    //  Position of the version field in the greeting.
     const size_t version_pos = 10;
 
     //  Is the peer using the unversioned protocol?

src/stream_engine.hpp

@@ -91,15 +91,9 @@ namespace zmq
         //  Underlying socket.
         fd_t s;
 
-        //  Maximum size of a greeting message:
-        //  preamble (10 bytes) + version (1 byte) + remaining_length (1 byte) +
-        //  up to 255 remaining bytes.
-        const static size_t maximum_greeting_size = 10 + 1 + 1 + 255;
-
-        //  Size of v1 greeting message:
-        //  preamble (10 bytes) + version (1 byte) + remaining_length (1 byte) +
-        //  socket_type (1)
-        const static size_t v1_greeting_size = 10 + 1 + 1 + 1;
+        //  Size of the greeting message:
+        //  Preamble (10 bytes) + version (1 byte) + socket type (1 byte).
+        const static size_t greeting_size = 12;
 
         handle_t handle;
 
@@ -119,18 +113,15 @@ namespace zmq
 
         //  The receive buffer holding the greeting message
         //  that we are receiving from the peer.
-        unsigned char greeting [maximum_greeting_size];
+        unsigned char greeting [greeting_size];
 
         //  The number of bytes of the greeting message that
         //  we have already received.
         unsigned int greeting_bytes_read;
 
-        //  The size of the greeting message.
-        unsigned int greeting_size;
-
         //  The send buffer holding the greeting message
         //  that we are sending to the peer.
-        unsigned char greeting_output_buffer [v1_greeting_size];
+        unsigned char greeting_output_buffer [greeting_size];
 
         //  The session this engine is attached to.
         zmq::session_base_t *session;