Multi-hop REQ/REP, part I., tracerouting switched on on XREP socket

src/i_engine.hpp

@@ -20,6 +20,8 @@
 #ifndef __ZMQ_I_ENGINE_HPP_INCLUDED__
 #define __ZMQ_I_ENGINE_HPP_INCLUDED__
 
+#include <stddef.h>
+
 namespace zmq
 {
 
@@ -36,6 +38,12 @@ namespace zmq
         //  This method is called by the session to signalise that there
         //  are messages to send available.
         virtual void revive () = 0;
+
+        //  Start tracing the message route. Engine should add the identity
+        //  supplied to all inbound messages and trim identity from all the
+        //  outbound messages.
+        virtual void traceroute (unsigned char *identity_,
+            size_t identity_size_) = 0;
     };
 
 }

src/pgm_receiver.cpp

@@ -88,6 +88,13 @@ void zmq::pgm_receiver_t::revive ()
     zmq_assert (false);
 }
 
+void zmq::pgm_receiver_t::traceroute (unsigned char *identity_,
+    size_t identity_size_)
+{
+    //  No need for tracerouting functionality in PGM socket at the moment.
+    zmq_assert (false);
+}
+
 void zmq::pgm_receiver_t::in_event ()
 {
     // Read data from the underlying pgm_socket.
@@ -151,7 +158,7 @@ void zmq::pgm_receiver_t::in_event ()
             it->second.joined = true;
 
             //  Create and connect decoder for the peer.
-            it->second.decoder = new (std::nothrow) zmq_decoder_t (0, NULL, 0);
+            it->second.decoder = new (std::nothrow) zmq_decoder_t (0);
             it->second.decoder->set_inout (inout);
         }
 

src/pgm_receiver.hpp

@@ -54,6 +54,7 @@ namespace zmq
         void plug (struct i_inout *inout_);
         void unplug ();
         void revive ();
+        void traceroute (unsigned char *identity_, size_t identity_size_);
 
         //  i_poll_events interface implementation.
         void in_event ();

src/pgm_sender.cpp

@@ -36,7 +36,7 @@
 zmq::pgm_sender_t::pgm_sender_t (io_thread_t *parent_, 
       const options_t &options_) :
     io_object_t (parent_),
-    encoder (0, false),
+    encoder (0),
     pgm_socket (false, options_),
     options (options_),
     out_buffer (NULL),
@@ -102,6 +102,13 @@ void zmq::pgm_sender_t::revive ()
     out_event ();
 }
 
+void zmq::pgm_sender_t::traceroute (unsigned char *identity_,
+    size_t identity_size_)
+{
+    //  No need for tracerouting functionality in PGM socket at the moment.
+    zmq_assert (false);
+}
+
 zmq::pgm_sender_t::~pgm_sender_t ()
 {
     if (out_buffer) {

src/pgm_sender.hpp

@@ -52,6 +52,7 @@ namespace zmq
         void plug (struct i_inout *inout_);
         void unplug ();
         void revive ();
+        void traceroute (unsigned char *identity_, size_t identity_size_);
 
         //  i_poll_events interface implementation.
         void in_event ();

src/zmq_decoder.cpp

@@ -25,24 +25,14 @@
 #include "wire.hpp"
 #include "err.hpp"
 
-zmq::zmq_decoder_t::zmq_decoder_t (size_t bufsize_,
+zmq::zmq_decoder_t::zmq_decoder_t (size_t bufsize_) :
-      void *prefix_, size_t prefix_size_) :
     decoder_t <zmq_decoder_t> (bufsize_),
-    destination (NULL)
+    destination (NULL),
+    prefix (NULL),
+    prefix_size (0)
 {
     zmq_msg_init (&in_progress);
 
-    if (!prefix_) {
-        prefix = NULL;
-        prefix_size = 0;
-    }
-    else {
-        prefix = malloc (prefix_size_);
-        zmq_assert (prefix);
-        memcpy (prefix, prefix_, prefix_size_);
-        prefix_size = prefix_size_;
-    }
-
     //  At the beginning, read one byte and go to one_byte_size_ready state.
     next_step (tmpbuf, 1, &zmq_decoder_t::one_byte_size_ready);
 }
@@ -60,6 +50,15 @@ void zmq::zmq_decoder_t::set_inout (i_inout *destination_)
     destination = destination_;
 }
 
+void zmq::zmq_decoder_t::add_prefix (unsigned char *prefix_,
+    size_t prefix_size_)
+{
+    prefix = malloc (prefix_size_);
+    zmq_assert (prefix);
+    memcpy (prefix, prefix_, prefix_size_);
+    prefix_size = prefix_size_;
+}
+
 bool zmq::zmq_decoder_t::one_byte_size_ready ()
 {
     //  First byte of size is read. If it is 0xff read 8-byte size.

src/zmq_decoder.hpp

@@ -34,11 +34,15 @@ namespace zmq
 
         //  If prefix is not NULL, it will be glued to the beginning of every
         //  decoded message.
-        zmq_decoder_t (size_t bufsize_, void *prefix_, size_t prefix_size_);
+        zmq_decoder_t (size_t bufsize_);
         ~zmq_decoder_t ();
 
         void set_inout (struct i_inout *destination_);
 
+        //  Once called, all decoded messages will be prefixed by the specified
+        //  prefix.
+        void add_prefix (unsigned char *prefix_, size_t prefix_size_);
+
     private:
 
         bool one_byte_size_ready ();

src/zmq_encoder.cpp

@@ -21,10 +21,10 @@
 #include "i_inout.hpp"
 #include "wire.hpp"
 
-zmq::zmq_encoder_t::zmq_encoder_t (size_t bufsize_, bool trim_prefix_) :
+zmq::zmq_encoder_t::zmq_encoder_t (size_t bufsize_) :
     encoder_t <zmq_encoder_t> (bufsize_),
     source (NULL),
-    trim_prefix (trim_prefix_)
+    trim (false)
 {
     zmq_msg_init (&in_progress);
 
@@ -42,10 +42,15 @@ void zmq::zmq_encoder_t::set_inout (i_inout *source_)
     source = source_;
 }
 
+void zmq::zmq_encoder_t::trim_prefix ()
+{
+    trim = true;
+}
+
 bool zmq::zmq_encoder_t::size_ready ()
 {
     //  Write message body into the buffer.
-    if (!trim_prefix) {
+    if (!trim) {
         next_step (zmq_msg_data (&in_progress), zmq_msg_size (&in_progress),
             &zmq_encoder_t::message_ready, false);
     }
@@ -75,7 +80,7 @@ bool zmq::zmq_encoder_t::message_ready ()
     //  Get the message size. If the prefix is not to be sent, adjust the
     //  size accordingly.
     size_t size = zmq_msg_size (&in_progress);
-    if (trim_prefix)
+    if (trim)
         size -= *(unsigned char*) zmq_msg_data (&in_progress);
 
     //  For messages less than 255 bytes long, write one byte of message size.

src/zmq_encoder.hpp

@@ -32,11 +32,15 @@ namespace zmq
     {
     public:
 
-        zmq_encoder_t (size_t bufsize_, bool trim_prefix_);
+        zmq_encoder_t (size_t bufsize_);
         ~zmq_encoder_t ();
 
         void set_inout (struct i_inout *source_);
 
+        //  Once called, encoder will start trimming frefixes from outbound
+        //  messages.
+        void trim_prefix ();
+
     private:
 
         bool size_ready ();
@@ -46,7 +50,7 @@ namespace zmq
         ::zmq_msg_t in_progress;
         unsigned char tmpbuf [9];
 
-        bool trim_prefix;
+        bool trim;
 
         zmq_encoder_t (const zmq_encoder_t&);
         void operator = (const zmq_encoder_t&);

src/zmq_engine.cpp

@@ -32,10 +32,10 @@ zmq::zmq_engine_t::zmq_engine_t (io_thread_t *parent_, fd_t fd_,
     io_object_t (parent_),
     inpos (NULL),
     insize (0),
-    decoder (in_batch_size, NULL, 0),
+    decoder (in_batch_size),
     outpos (NULL),
     outsize (0),
-    encoder (out_batch_size, false),
+    encoder (out_batch_size),
     inout (NULL),
     options (options_),
     reconnect (reconnect_)
@@ -160,6 +160,13 @@ void zmq::zmq_engine_t::revive ()
     out_event ();
 }
 
+void zmq::zmq_engine_t::traceroute (unsigned char *identity_,
+    size_t identity_size_)
+{
+    encoder.trim_prefix ();
+    decoder.add_prefix (identity_, identity_size_);
+}
+
 void zmq::zmq_engine_t::error ()
 {
     zmq_assert (inout);

src/zmq_engine.hpp

@@ -47,6 +47,7 @@ namespace zmq
         void plug (struct i_inout *inout_);
         void unplug ();
         void revive ();
+        void traceroute (unsigned char *identity_, size_t identity_size_);
 
         //  i_poll_events interface implementation.
         void in_event ();

src/zmq_init.cpp

@@ -76,6 +76,12 @@ bool zmq::zmq_init_t::write (::zmq_msg_t *msg_)
         zmq_msg_size (msg_));
     received = true;
 
+    //  Once the initial handshaking is over, XREP sockets should start
+    //  tracerouting individual messages.
+    if (options.type == ZMQ_XREP)
+        engine->traceroute ((unsigned char*) peer_identity.data (),
+            peer_identity.size ());
+
     return true;
 }