Implement protocol versioning (except PGM)

Implements SP protocol versioning, legacy protocol support, and the
following pattern protocol versions:

PAIR:     v2
PUBSUB:   v1 (legacy), v3
REQREP:   v1
PIPELINE: v2
SURVEY:   v1

Engine support is only for stream_engine_t at this stage.

Signed-off-by: Martin Lucina <martin@lucina.net>

28 files changed, 481 insertions, 55 deletions

diff --git a/src/options.cpp b/src/options.cpp
index f7bbdc4..d362c18 100644
--- a/src/options.cpp
+++ b/src/options.cpp
@@ -48,7 +48,11 @@ xs::options_t::options_t () :
     sndtimeo (-1),
     ipv4only (1),
     keepalive (0),
-    protocol (0),
+    legacy_protocol (false),
+    sp_pattern (-1),
+    sp_version (-1),
+    sp_role (-1),
+    sp_complement (-1),
     filter (XS_FILTER_PREFIX),
     survey_timeout (-1),
     delay_on_close (true),
@@ -236,21 +240,6 @@ int xs::options_t::setsockopt (int option_, const void *optval_,
             return 0;
         }
 
-    case XS_PROTOCOL:
-        {
-            if (optvallen_ != sizeof (int)) {
-                errno = EINVAL;
-                return -1;
-            }
-            int val = *((int*) optval_);
-            if (val < 0) {
-                errno = EINVAL;
-                return -1;
-            }
-            protocol = val;
-            return 0;
-        }
-
     case XS_FILTER:
         if (optvallen_ != sizeof (int)) {
             errno = EINVAL;
@@ -457,7 +446,7 @@ int xs::options_t::getsockopt (int option_, void *optval_, size_t *optvallen_)
             errno = EINVAL;
             return -1;
         }
-        *((int*) optval_) = protocol;
+        *((int*) optval_) = sp_version;
         *optvallen_ = sizeof (int);
         return 0;
 
diff --git a/src/options.hpp b/src/options.hpp
index 805f793..89d6d2a 100644
--- a/src/options.hpp
+++ b/src/options.hpp
@@ -92,8 +92,14 @@ namespace xs
         //  If 1, keepalives are to be sent periodically.
         int keepalive;
 
-        //  Version of wire protocol to use.
-        int protocol;
+        //  If true, the legacy non-SP wire protocol is in use.
+        bool legacy_protocol;
+
+        //  SP protocol pattern, version, role and complementary role.
+        int sp_pattern;
+        int sp_version;
+        int sp_role;
+        int sp_complement;
 
         //  Filter ID to be used with subscriptions and unsubscriptions.
         int filter;
diff --git a/src/pair.cpp b/src/pair.cpp
index b4cb0b4..d4f699e 100644
--- a/src/pair.cpp
+++ b/src/pair.cpp
@@ -23,12 +23,17 @@
 #include "err.hpp"
 #include "pipe.hpp"
 #include "msg.hpp"
+#include "wire.hpp"
 
 xs::pair_t::pair_t (class ctx_t *parent_, uint32_t tid_, int sid_) :
     socket_base_t (parent_, tid_, sid_),
     pipe (NULL)
 {
     options.type = XS_PAIR;
+    options.sp_pattern = SP_PAIR;
+    options.sp_role = SP_PAIR_PAIR;
+    options.sp_version = 2;
+    options.sp_complement = SP_PAIR_PAIR;
 }
 
 xs::pair_t::~pair_t ()
@@ -36,6 +41,34 @@ xs::pair_t::~pair_t ()
     xs_assert (!pipe);
 }
 
+int xs::pair_t::xsetsockopt (int option_, const void *optval_,
+    size_t optvallen_)
+{
+    if (option_ != XS_PROTOCOL) {
+        errno = EINVAL;
+        return -1;
+    }
+
+    if (optvallen_ != sizeof (int)) {
+        errno = EINVAL;
+        return -1;
+    }
+
+    if (!optval_) {
+        errno = EFAULT;
+        return -1;
+    }
+
+    int version = *(int *) optval_;
+    if (version != 2) {
+        errno = EINVAL;
+        return -1;
+    }
+
+    options.sp_version = version;
+    return 0;
+}
+
 void xs::pair_t::xattach_pipe (pipe_t *pipe_, bool icanhasall_)
 {
     xs_assert (!pipe);
diff --git a/src/pair.hpp b/src/pair.hpp
index 07ed6c5..6a5f167 100644
--- a/src/pair.hpp
+++ b/src/pair.hpp
@@ -42,6 +42,7 @@ namespace xs
         ~pair_t ();
 
         //  Overloads of functions from socket_base_t.
+        int xsetsockopt (int option_, const void *optval_, size_t optvallen_);
         void xattach_pipe (xs::pipe_t *pipe_, bool icanhasall_);
         int xsend (xs::msg_t *msg_, int flags_);
         int xrecv (xs::msg_t *msg_, int flags_);
diff --git a/src/pipe.cpp b/src/pipe.cpp
index 0a15cc0..c14642f 100644
--- a/src/pipe.cpp
+++ b/src/pipe.cpp
@@ -27,7 +27,7 @@
 #include "err.hpp"
 
 int xs::pipepair (class object_t *parents_ [2], class pipe_t* pipes_ [2],
-    int hwms_ [2], bool delays_ [2], int protocol_)
+    int hwms_ [2], bool delays_ [2], int sp_version_)
 {
     //   Creates two pipe objects. These objects are connected by two ypipes,
     //   each to pass messages in one direction.
@@ -38,10 +38,10 @@ int xs::pipepair (class object_t *parents_ [2], class pipe_t* pipes_ [2],
     alloc_assert (upipe2);
 
     pipes_ [0] = new (std::nothrow) pipe_t (parents_ [0], upipe1, upipe2,
-        hwms_ [1], hwms_ [0], delays_ [0], protocol_);
+        hwms_ [1], hwms_ [0], delays_ [0], sp_version_);
     alloc_assert (pipes_ [0]);
     pipes_ [1] = new (std::nothrow) pipe_t (parents_ [1], upipe2, upipe1,
-        hwms_ [0], hwms_ [1], delays_ [1], protocol_);
+        hwms_ [0], hwms_ [1], delays_ [1], sp_version_);
     alloc_assert (pipes_ [1]);
 
     pipes_ [0]->set_peer (pipes_ [1]);
@@ -51,7 +51,7 @@ int xs::pipepair (class object_t *parents_ [2], class pipe_t* pipes_ [2],
 }
 
 xs::pipe_t::pipe_t (object_t *parent_, upipe_t *inpipe_, upipe_t *outpipe_,
-      int inhwm_, int outhwm_, bool delay_, int protocol_) :
+      int inhwm_, int outhwm_, bool delay_, int sp_version_) :
     object_t (parent_),
     inpipe (inpipe_),
     outpipe (outpipe_),
@@ -66,7 +66,7 @@ xs::pipe_t::pipe_t (object_t *parent_, upipe_t *inpipe_, upipe_t *outpipe_,
     sink (NULL),
     state (active),
     delay (delay_),
-    protocol (protocol_)
+    sp_version (sp_version_)
 {
 }
 
@@ -386,9 +386,9 @@ void xs::pipe_t::terminate (bool delay_)
     }
 }
 
-int xs::pipe_t::get_protocol ()
+int xs::pipe_t::get_sp_version ()
 {
-    return protocol;
+    return sp_version;
 }
 
 bool xs::pipe_t::is_delimiter (msg_t &msg_)
diff --git a/src/pipe.hpp b/src/pipe.hpp
index c298154..dbc6b7e 100644
--- a/src/pipe.hpp
+++ b/src/pipe.hpp
@@ -44,7 +44,7 @@ namespace xs
     //  pipe receives all the pending messages before terminating, otherwise it
     //  terminates straight away.
     int pipepair (xs::object_t *parents_ [2], xs::pipe_t* pipes_ [2],
-        int hwms_ [2], bool delays_ [2], int protocol_);
+        int hwms_ [2], bool delays_ [2], int sp_version_);
 
     struct i_pipe_events
     {
@@ -69,7 +69,7 @@ namespace xs
         //  This allows pipepair to create pipe objects.
         friend int pipepair (xs::object_t *parents_ [2],
             xs::pipe_t* pipes_ [2], int hwms_ [2], bool delays_ [2],
-            int protocol_);
+            int sp_version_);
 
     public:
 
@@ -111,8 +111,8 @@ namespace xs
         //  before actual shutdown.
         void terminate (bool delay_);
 
-        //  Returns the ID of the protocol associated with the pipe.
-        int get_protocol ();
+        //  Returns the SP pattern version in use on this pipe.
+        int get_sp_version ();
 
     private:
 
@@ -132,7 +132,7 @@ namespace xs
         //  Constructor is private. Pipe can only be created using
         //  pipepair function.
         pipe_t (object_t *parent_, upipe_t *inpipe_, upipe_t *outpipe_,
-            int inhwm_, int outhwm_, bool delay_, int protocol_);
+            int inhwm_, int outhwm_, bool delay_, int sp_version_);
 
         //  Pipepair uses this function to let us know about
         //  the peer pipe object.
@@ -192,9 +192,9 @@ namespace xs
         //  asks us to.
         bool delay;
 
-        //  ID of the protocol to use. This value is not used by the pipe
-        //  itself, rather it's used by the users of the pipe.
-        int protocol;
+        //  SP pattern version in use on this pipe. This value is used by the
+        //  pattern classes using the pipe, not the pipe itself.
+        int sp_version;
 
         //  Identity of the writer. Used uniquely by the reader side.
         blob_t identity;
diff --git a/src/pull.cpp b/src/pull.cpp
index 8ae8208..4d08edb 100644
--- a/src/pull.cpp
+++ b/src/pull.cpp
@@ -23,17 +23,50 @@
 #include "err.hpp"
 #include "msg.hpp"
 #include "pipe.hpp"
+#include "wire.hpp"
 
 xs::pull_t::pull_t (class ctx_t *parent_, uint32_t tid_, int sid_) :
     socket_base_t (parent_, tid_, sid_)
 {
     options.type = XS_PULL;
+    options.sp_pattern = SP_PIPELINE;
+    options.sp_version = 2;
+    options.sp_role = SP_PIPELINE_PULL;
+    options.sp_complement = SP_PIPELINE_PUSH;
 }
 
 xs::pull_t::~pull_t ()
 {
 }
 
+int xs::pull_t::xsetsockopt (int option_, const void *optval_,
+    size_t optvallen_)
+{
+    if (option_ != XS_PROTOCOL) {
+        errno = EINVAL;
+        return -1;
+    }
+
+    if (optvallen_ != sizeof (int)) {
+        errno = EINVAL;
+        return -1;
+    }
+
+    if (!optval_) {
+        errno = EFAULT;
+        return -1;
+    }
+
+    int version = *(int *) optval_;
+    if (version != 2) {
+        errno = EINVAL;
+        return -1;
+    }
+
+    options.sp_version = version;
+    return 0;
+}
+
 void xs::pull_t::xattach_pipe (pipe_t *pipe_, bool icanhasall_)
 {
     xs_assert (pipe_);
diff --git a/src/pull.hpp b/src/pull.hpp
index 04da465..5453bbd 100644
--- a/src/pull.hpp
+++ b/src/pull.hpp
@@ -45,6 +45,7 @@ namespace xs
     protected:
 
         //  Overloads of functions from socket_base_t.
+        int xsetsockopt (int option_, const void *optval_, size_t optvallen_);
         void xattach_pipe (xs::pipe_t *pipe_, bool icanhasall_);
         int xrecv (xs::msg_t *msg_, int flags_);
         bool xhas_in ();
diff --git a/src/push.cpp b/src/push.cpp
index 59f508f..94f8381 100644
--- a/src/push.cpp
+++ b/src/push.cpp
@@ -23,17 +23,50 @@
 #include "pipe.hpp"
 #include "err.hpp"
 #include "msg.hpp"
+#include "wire.hpp"
 
 xs::push_t::push_t (class ctx_t *parent_, uint32_t tid_, int sid_) :
     socket_base_t (parent_, tid_, sid_)
 {
     options.type = XS_PUSH;
+    options.sp_pattern = SP_PIPELINE;
+    options.sp_version = 2;
+    options.sp_role = SP_PIPELINE_PUSH;
+    options.sp_complement = SP_PIPELINE_PULL;
 }
 
 xs::push_t::~push_t ()
 {
 }
 
+int xs::push_t::xsetsockopt (int option_, const void *optval_,
+    size_t optvallen_)
+{
+    if (option_ != XS_PROTOCOL) {
+        errno = EINVAL;
+        return -1;
+    }
+
+    if (optvallen_ != sizeof (int)) {
+        errno = EINVAL;
+        return -1;
+    }
+
+    if (!optval_) {
+        errno = EFAULT;
+        return -1;
+    }
+
+    int version = *(int *) optval_;
+    if (version != 2) {
+        errno = EINVAL;
+        return -1;
+    }
+
+    options.sp_version = version;
+    return 0;
+}
+
 void xs::push_t::xattach_pipe (pipe_t *pipe_, bool icanhasall_)
 {
     xs_assert (pipe_);
diff --git a/src/push.hpp b/src/push.hpp
index a112f31..ffe16cc 100644
--- a/src/push.hpp
+++ b/src/push.hpp
@@ -45,6 +45,7 @@ namespace xs
     protected:
 
         //  Overloads of functions from socket_base_t.
+        int xsetsockopt (int option_, const void *optval_, size_t optvallen_);
         void xattach_pipe (xs::pipe_t *pipe_, bool icanhasall_);
         int xsend (xs::msg_t *msg_, int flags_);
         bool xhas_out ();
diff --git a/src/session_base.cpp b/src/session_base.cpp
index 35c4a4e..9b58b42 100644
--- a/src/session_base.cpp
+++ b/src/session_base.cpp
@@ -298,7 +298,7 @@ void xs::session_base_t::process_attach (i_engine *engine_)
         pipe_t *pipes [2] = {NULL, NULL};
         int hwms [2] = {options.rcvhwm, options.sndhwm};
         bool delays [2] = {options.delay_on_close, options.delay_on_disconnect};
-        int rc = pipepair (parents, pipes, hwms, delays, options.protocol);
+        int rc = pipepair (parents, pipes, hwms, delays, options.sp_version);
         errno_assert (rc == 0);
 
         //  Plug the local end of the pipe.
diff --git a/src/socket_base.cpp b/src/socket_base.cpp
index ec5c8bd..e8ae28a 100644
--- a/src/socket_base.cpp
+++ b/src/socket_base.cpp
@@ -447,7 +447,7 @@ int xs::socket_base_t::connect (const char *addr_)
         pipe_t *ppair [2] = {NULL, NULL};
         int hwms [2] = {sndhwm, rcvhwm};
         bool delays [2] = {options.delay_on_disconnect, options.delay_on_close};
-        rc = pipepair (parents, ppair, hwms, delays, options.protocol);
+        rc = pipepair (parents, ppair, hwms, delays, options.sp_version);
         errno_assert (rc == 0);
 
         //  Attach local end of the pipe to this socket object.
@@ -501,7 +501,7 @@ int xs::socket_base_t::connect (const char *addr_)
     pipe_t *ppair [2] = {NULL, NULL};
     int hwms [2] = {options.sndhwm, options.rcvhwm};
     bool delays [2] = {options.delay_on_disconnect, options.delay_on_close};
-    rc = pipepair (parents, ppair, hwms, delays, options.protocol);
+    rc = pipepair (parents, ppair, hwms, delays, options.sp_version);
     errno_assert (rc == 0);
 
     // PGM does not support subscription forwarding; ask for all data to be
diff --git a/src/stream_engine.cpp b/src/stream_engine.cpp
index 15b566b..a39b410 100644
--- a/src/stream_engine.cpp
+++ b/src/stream_engine.cpp
@@ -53,8 +53,21 @@ xs::stream_engine_t::stream_engine_t (fd_t fd_, const options_t &options_) :
     session (NULL),
     leftover_session (NULL),
     options (options_),
-    plugged (false)
+    plugged (false),
+    header_pos (in_header),
+    header_remaining (sizeof in_header),
+    header_received (false),
+    header_sent (false)
 {
+    //  Fill in outgoing SP protocol header and the complementary (desired)
+    //  header.
+    if (!options.legacy_protocol) {
+        sp_get_header (out_header, options.sp_pattern, options.sp_version,
+            options.sp_role);
+        sp_get_header (desired_header, options.sp_pattern, options.sp_version,
+            options.sp_complement);
+    }
+
     //  Get the socket into non-blocking mode.
     unblock_socket (s);
 
@@ -155,6 +168,35 @@ void xs::stream_engine_t::in_event (fd_t fd_)
 {
     bool disconnection = false;
 
+    //  If we have not yet received the full protocol header...
+    if (unlikely (!options.legacy_protocol && !header_received)) {
+
+        //  Read remaining header bytes.
+        int hbytes = read (header_pos, header_remaining);
+
+        //  Check whether the peer has closed the connection.
+        if (hbytes == -1) {
+            error ();
+            return;
+        }
+
+        header_remaining -= hbytes;
+        header_pos += hbytes;
+
+        //  If we did not read the whole header, poll for more.
+        if (header_remaining)
+            return;
+
+        //  If the protocol headers do not match, close the connection.
+        if (memcmp (in_header, desired_header, sizeof in_header) != 0) {
+            error ();
+            return;
+        }
+
+        //  Done with protocol header; proceed to read data.
+        header_received = true;
+    }
+
     //  If there's no data to process in the buffer...
     if (!insize) {
 
@@ -210,6 +252,20 @@ void xs::stream_engine_t::out_event (fd_t fd_)
 {
     bool more_data = true;
 
+    //  If protocol header was not yet sent...
+    if (unlikely (!options.legacy_protocol && !header_sent)) {
+        int hbytes = write (out_header, sizeof out_header);
+
+        //  It should always be possible to write the full protocol header to a
+        //  freshly connected TCP socket. Therefore, if we get an error or
+        //  partial write here the peer has disconnected.
+        if (hbytes != sizeof out_header) {
+            error ();
+            return;
+        }
+        header_sent = true;
+    }
+
     //  If write buffer is empty, try to read new data from the encoder.
     if (!outsize) {
 
diff --git a/src/stream_engine.hpp b/src/stream_engine.hpp
index 46a6080..70c9ddb 100644
--- a/src/stream_engine.hpp
+++ b/src/stream_engine.hpp
@@ -30,6 +30,7 @@
 #include "encoder.hpp"
 #include "decoder.hpp"
 #include "options.hpp"
+#include "wire.hpp"
 
 namespace xs
 {
@@ -98,6 +99,22 @@ namespace xs
 
         bool plugged;
 
+        //  Outgoing protocol header.
+        sp_header_t out_header;
+
+        //  Desired protocol header.
+        sp_header_t desired_header;
+
+        //  Incoming protocol header.
+        sp_header_t in_header;
+
+        unsigned char *header_pos;
+        size_t header_remaining;
+
+        //  Protocol header has been received/sent.
+        bool header_received;
+        bool header_sent;
+
         stream_engine_t (const stream_engine_t&);
         const stream_engine_t &operator = (const stream_engine_t&);
     };
diff --git a/src/sub.cpp b/src/sub.cpp
index d29ae8d..79cb63c 100644
--- a/src/sub.cpp
+++ b/src/sub.cpp
@@ -48,8 +48,7 @@ int xs::sub_t::xsetsockopt (int option_, const void *optval_,
     size_t optvallen_)
 {
     if (option_ != XS_SUBSCRIBE && option_ != XS_UNSUBSCRIBE) {
-        errno = EINVAL;
-        return -1;
+        return xsub_t::xsetsockopt (option_, optval_, optvallen_);
     }
 
     if (optvallen_ > 0 && !optval_) {
@@ -202,7 +201,7 @@ int xs::sub_t::filter_subscribed (const unsigned char *data_, size_t size_)
     int rc = msg.init_size (size_ + 4);
     errno_assert (rc == 0);
     unsigned char *data = (unsigned char*) msg.data ();
-    put_uint16 (data, XS_CMD_SUBSCRIBE);
+    put_uint16 (data, SP_PUBSUB_CMD_SUBSCRIBE);
     put_uint16 (data + 2, options.filter);
     memcpy (data + 4, data_, size_);
 
@@ -225,7 +224,7 @@ int xs::sub_t::filter_unsubscribed (const unsigned char *data_, size_t size_)
     int rc = msg.init_size (size_ + 4);
     errno_assert (rc == 0);
     unsigned char *data = (unsigned char*) msg.data ();
-    put_uint16 (data, XS_CMD_UNSUBSCRIBE);
+    put_uint16 (data, SP_PUBSUB_CMD_UNSUBSCRIBE);
     put_uint16 (data + 2, options.filter);
     memcpy (data + 4, data_, size_);
 
diff --git a/src/wire.hpp b/src/wire.hpp
index f840fce..e751818 100644
--- a/src/wire.hpp
+++ b/src/wire.hpp
@@ -24,11 +24,50 @@
 #include "stdint.hpp"
 
 //  Protocol-related constants.
-#define XS_CMD_SUBSCRIBE 1
-#define XS_CMD_UNSUBSCRIBE 2
+
+//  Protocol header.
+#define SP_HEADER_LENGTH 8
+
+//  Patterns.
+#define SP_PAIR 1
+#define SP_PUBSUB 2
+#define SP_REQREP 3
+#define SP_PIPELINE 4
+#define SP_SURVEY 5
+
+//  Roles.
+#define SP_PAIR_PAIR 1
+#define SP_PUBSUB_PUB 1
+#define SP_PUBSUB_SUB 2
+#define SP_REQREP_REQ 1
+#define SP_REQREP_REP 2
+#define SP_PIPELINE_PUSH 1
+#define SP_PIPELINE_PULL 2
+#define SP_SURVEY_SURVEYOR 1
+#define SP_SURVEY_RESPONDENT 2
+
+//  PUBSUB pattern commands.
+#define SP_PUBSUB_CMD_SUBSCRIBE 1
+#define SP_PUBSUB_CMD_UNSUBSCRIBE 2
 
 namespace xs
 {
+    //  Protocol header type.
+    typedef unsigned char sp_header_t [SP_HEADER_LENGTH];
+
+    //  Get the SP protocol header for the specified pattern, version and role.
+    inline void sp_get_header (sp_header_t header_, int pattern_, int version_,
+        int role_)
+    {
+        header_ [0] = 0;
+        header_ [1] = 0;
+        header_ [2] = 'S';
+        header_ [3] = 'P';
+        header_ [4] = pattern_ & 0xff;
+        header_ [5] = version_ & 0xff;
+        header_ [6] = role_ & 0xff;
+        header_ [7] = 0;
+    }
 
     //  Helper functions to convert different integer types to/from network
     //  byte order.
diff --git a/src/xpub.cpp b/src/xpub.cpp
index fe0b9a7..b176bf8 100644
--- a/src/xpub.cpp
+++ b/src/xpub.cpp
@@ -35,6 +35,10 @@ xs::xpub_t::xpub_t (class ctx_t *parent_, uint32_t tid_, int sid_) :
     tmp_filter_id (-1)
 {
     options.type = XS_XPUB;
+    options.sp_pattern = SP_PUBSUB;
+    options.sp_version = 3;
+    options.sp_role = SP_PUBSUB_PUB;
+    options.sp_complement = SP_PUBSUB_SUB;
 }
 
 xs::xpub_t::~xpub_t ()
@@ -44,6 +48,42 @@ xs::xpub_t::~xpub_t ()
         it->type->pf_destroy ((void*) (core_t*) this, it->instance);
 }
 
+int xs::xpub_t::xsetsockopt (int option_, const void *optval_,
+    size_t optvallen_)
+{
+    if (option_ != XS_PROTOCOL) {
+        errno = EINVAL;
+        return -1;
+    }
+
+    if (optvallen_ != sizeof (int)) {
+        errno = EINVAL;
+        return -1;
+    }
+
+    if (!optval_) {
+        errno = EFAULT;
+        return -1;
+    }
+
+    int version = *(int *) optval_;
+    switch (version) {
+    case 1:
+        options.legacy_protocol = true;
+        options.sp_version = 1;
+        break;
+    case 3:
+        options.legacy_protocol = false;
+        options.sp_version = 3;
+        break;
+    default:
+        errno = EINVAL;
+        return -1;
+    }
+
+    return 0;
+}
+
 void xs::xpub_t::xattach_pipe (pipe_t *pipe_, bool icanhasall_)
 {
     xs_assert (pipe_);
@@ -53,7 +93,7 @@ void xs::xpub_t::xattach_pipe (pipe_t *pipe_, bool icanhasall_)
     //  to all data on this pipe, implicitly. Also, if we are using
     //  0MQ/2.1-style protocol, there's no subscription forwarding. Thus,
     //  we need to subscribe for all messages automatically.
-    if (icanhasall_|| pipe_->get_protocol () == 1) {
+    if (icanhasall_|| pipe_->get_sp_version () == 1) {
 
         //  Find the prefix filter.
         //  TODO: Change this to ALL filter.
@@ -121,7 +161,8 @@ void xs::xpub_t::xread_activated (pipe_t *pipe_)
         int filter_id = XS_FILTER_PREFIX;
 #endif
 
-        if (cmd != XS_CMD_SUBSCRIBE && cmd != XS_CMD_UNSUBSCRIBE) {
+        if (cmd != SP_PUBSUB_CMD_SUBSCRIBE &&
+              cmd != SP_PUBSUB_CMD_UNSUBSCRIBE) {
             sub.close ();
             return;
         }
@@ -133,7 +174,7 @@ void xs::xpub_t::xread_activated (pipe_t *pipe_)
                 break;
 
         bool unique;
-		if (cmd == XS_CMD_UNSUBSCRIBE) {
+		if (cmd == SP_PUBSUB_CMD_UNSUBSCRIBE) {
             xs_assert (it != filters.end ());
             unique = it->type->pf_unsubscribe ((void*) (core_t*) this,
                 it->instance, pipe_, data + 4, size - 4) ? true : false;
@@ -258,7 +299,7 @@ int xs::xpub_t::filter_unsubscribed (const unsigned char *data_, size_t size_)
 		//  Place the unsubscription to the queue of pending (un)sunscriptions
 		//  to be retrived by the user later on.
 		blob_t unsub (size_ + 4, 0);
-        put_uint16 ((unsigned char*) unsub.data (), XS_CMD_UNSUBSCRIBE);
+        put_uint16 ((unsigned char*) unsub.data (), SP_PUBSUB_CMD_UNSUBSCRIBE);
         put_uint16 ((unsigned char*) unsub.data () + 2, tmp_filter_id);
 		memcpy ((void*) (unsub.data () + 4), data_, size_);
 
diff --git a/src/xpub.hpp b/src/xpub.hpp
index c0e47ff..f9cb737 100644
--- a/src/xpub.hpp
+++ b/src/xpub.hpp
@@ -49,6 +49,7 @@ namespace xs
         ~xpub_t ();
 
         //  Implementations of virtual functions from socket_base_t.
+        int xsetsockopt (int option_, const void *optval_, size_t optvallen_);
         void xattach_pipe (xs::pipe_t *pipe_, bool icanhasall_);
         int xsend (xs::msg_t *msg_, int flags_);
         bool xhas_out ();
diff --git a/src/xrep.cpp b/src/xrep.cpp
index 007ed27..5e9fc8a 100644
--- a/src/xrep.cpp
+++ b/src/xrep.cpp
@@ -36,6 +36,10 @@ xs::xrep_t::xrep_t (class ctx_t *parent_, uint32_t tid_, int sid_) :
     next_peer_id (generate_random ())
 {
     options.type = XS_XREP;
+    options.sp_pattern = SP_REQREP;
+    options.sp_version = 1;
+    options.sp_role = SP_REQREP_REP;
+    options.sp_complement = SP_REQREP_REQ;
 
     //  TODO: Uncomment the following line when XREP will become true XREP
     //  rather than generic router socket.
@@ -55,6 +59,34 @@ xs::xrep_t::~xrep_t ()
     prefetched_msg.close ();
 }
 
+int xs::xrep_t::xsetsockopt (int option_, const void *optval_,
+    size_t optvallen_)
+{
+    if (option_ != XS_PROTOCOL) {
+        errno = EINVAL;
+        return -1;
+    }
+
+    if (optvallen_ != sizeof (int)) {
+        errno = EINVAL;
+        return -1;
+    }
+
+    if (!optval_) {
+        errno = EFAULT;
+        return -1;
+    }
+
+    int version = *(int *) optval_;
+    if (version != 1) {
+        errno = EINVAL;
+        return -1;
+    }
+
+    options.sp_version = version;
+    return 0;
+}
+
 void xs::xrep_t::xattach_pipe (pipe_t *pipe_, bool icanhasall_)
 {
     xs_assert (pipe_);
diff --git a/src/xrep.hpp b/src/xrep.hpp
index 8e16a4c..71a7bf4 100644
--- a/src/xrep.hpp
+++ b/src/xrep.hpp
@@ -49,6 +49,7 @@ namespace xs
         ~xrep_t ();
 
         //  Overloads of functions from socket_base_t.
+        int xsetsockopt (int option_, const void *optval_, size_t optvallen_);
         void xattach_pipe (xs::pipe_t *pipe_, bool icanhasall_);
         int xsend (msg_t *msg_, int flags_);
         int xrecv (msg_t *msg_, int flags_);
diff --git a/src/xreq.cpp b/src/xreq.cpp
index 1c6af9d..e42c691 100644
--- a/src/xreq.cpp
+++ b/src/xreq.cpp
@@ -22,12 +22,17 @@
 #include "xreq.hpp"
 #include "err.hpp"
 #include "msg.hpp"
+#include "wire.hpp"
 
 xs::xreq_t::xreq_t (class ctx_t *parent_, uint32_t tid_, int sid_) :
     socket_base_t (parent_, tid_, sid_),
     prefetched (false)
 {
     options.type = XS_XREQ;
+    options.sp_pattern = SP_REQREP;
+    options.sp_version = 1;
+    options.sp_role = SP_REQREP_REQ;
+    options.sp_complement = SP_REQREP_REP;
 
     //  TODO: Uncomment the following line when XREQ will become true XREQ
     //  rather than generic dealer socket.
@@ -46,6 +51,34 @@ xs::xreq_t::~xreq_t ()
     prefetched_msg.close ();
 }
 
+int xs::xreq_t::xsetsockopt (int option_, const void *optval_,
+    size_t optvallen_)
+{
+    if (option_ != XS_PROTOCOL) {
+        errno = EINVAL;
+        return -1;
+    }
+
+    if (optvallen_ != sizeof (int)) {
+        errno = EINVAL;
+        return -1;
+    }
+
+    if (!optval_) {
+        errno = EFAULT;
+        return -1;
+    }
+
+    int version = *(int *) optval_;
+    if (version != 1) {
+        errno = EINVAL;
+        return -1;
+    }
+
+    options.sp_version = version;
+    return 0;
+}
+
 void xs::xreq_t::xattach_pipe (pipe_t *pipe_, bool icanhasall_)
 {
     xs_assert (pipe_);
diff --git a/src/xreq.hpp b/src/xreq.hpp
index c4f9baf..9fe6ebb 100644
--- a/src/xreq.hpp
+++ b/src/xreq.hpp
@@ -46,6 +46,7 @@ namespace xs
     protected:
 
         //  Overloads of functions from socket_base_t.
+        int xsetsockopt (int option_, const void *optval_, size_t optvallen_);
         void xattach_pipe (xs::pipe_t *pipe_, bool icanhasall_);
         int xsend (xs::msg_t *msg_, int flags_);
         int xrecv (xs::msg_t *msg_, int flags_);
diff --git a/src/xrespondent.cpp b/src/xrespondent.cpp
index c16d900..bd19913 100644
--- a/src/xrespondent.cpp
+++ b/src/xrespondent.cpp
@@ -35,6 +35,10 @@ xs::xrespondent_t::xrespondent_t (class ctx_t *parent_, uint32_t tid_,
     next_peer_id (generate_random ())
 {
     options.type = XS_XRESPONDENT;
+    options.sp_pattern = SP_SURVEY;
+    options.sp_version = 1;
+    options.sp_role = SP_SURVEY_RESPONDENT;
+    options.sp_complement = SP_SURVEY_SURVEYOR;
 
     //  If the connection disappears it makes no sense to read any more surveys
     //  from it. The responses will be unroutable anyway.
@@ -49,6 +53,34 @@ xs::xrespondent_t::~xrespondent_t ()
     prefetched_msg.close ();
 }
 
+int xs::xrespondent_t::xsetsockopt (int option_, const void *optval_,
+    size_t optvallen_)
+{
+    if (option_ != XS_PROTOCOL) {
+        errno = EINVAL;
+        return -1;
+    }
+
+    if (optvallen_ != sizeof (int)) {
+        errno = EINVAL;
+        return -1;
+    }
+
+    if (!optval_) {
+        errno = EFAULT;
+        return -1;
+    }
+
+    int version = *(int *) optval_;
+    if (version != 1) {
+        errno = EINVAL;
+        return -1;
+    }
+
+    options.sp_version = version;
+    return 0;
+}
+
 void xs::xrespondent_t::xattach_pipe (pipe_t *pipe_, bool icanhasall_)
 {
     xs_assert (pipe_);
diff --git a/src/xrespondent.hpp b/src/xrespondent.hpp
index eb6ac9a..4143e36 100644
--- a/src/xrespondent.hpp
+++ b/src/xrespondent.hpp
@@ -47,6 +47,7 @@ namespace xs
         ~xrespondent_t ();
 
         //  Overloads of functions from socket_base_t.
+        int xsetsockopt (int option_, const void *optval_, size_t optvallen_);
         void xattach_pipe (xs::pipe_t *pipe_, bool icanhasall_);
         int xsend (msg_t *msg_, int flags_);
         int xrecv (msg_t *msg_, int flags_);
diff --git a/src/xsub.cpp b/src/xsub.cpp
index 7272a8e..18acfea 100644
--- a/src/xsub.cpp
+++ b/src/xsub.cpp
@@ -29,6 +29,10 @@ xs::xsub_t::xsub_t (class ctx_t *parent_, uint32_t tid_, int sid_) :
     socket_base_t (parent_, tid_, sid_)
 {
     options.type = XS_XSUB;
+    options.sp_pattern = SP_PUBSUB;
+    options.sp_version = 3;
+    options.sp_role = SP_PUBSUB_SUB;
+    options.sp_complement = SP_PUBSUB_PUB;
 
     //  When socket is being closed down we don't want to wait till pending
     //  subscription commands are sent to the wire.
@@ -42,6 +46,42 @@ xs::xsub_t::~xsub_t ()
 {
 }
 
+int xs::xsub_t::xsetsockopt (int option_, const void *optval_,
+    size_t optvallen_)
+{
+    if (option_ != XS_PROTOCOL) {
+        errno = EINVAL;
+        return -1;
+    }
+
+    if (optvallen_ != sizeof (int)) {
+        errno = EINVAL;
+        return -1;
+    }
+
+    if (!optval_) {
+        errno = EFAULT;
+        return -1;
+    }
+
+    int version = *(int *) optval_;
+    switch (version) {
+    case 1:
+        options.legacy_protocol = true;
+        options.sp_version = 1;
+        break;
+    case 3:
+        options.legacy_protocol = false;
+        options.sp_version = 3;
+        break;
+    default:
+        errno = EINVAL;
+        return -1;
+    }
+
+    return 0;
+}
+
 void xs::xsub_t::xattach_pipe (pipe_t *pipe_, bool icanhasall_)
 {
     xs_assert (pipe_);
@@ -49,7 +89,7 @@ void xs::xsub_t::xattach_pipe (pipe_t *pipe_, bool icanhasall_)
 
     //  Pipes with 0MQ/2.1-style protocol are not eligible for accepting
     //  subscriptions.
-    if (pipe_->get_protocol () == 1)
+    if (pipe_->get_sp_version () == 1)
         return;
 
     dist.attach (pipe_);
@@ -75,14 +115,14 @@ void xs::xsub_t::xwrite_activated (pipe_t *pipe_)
 void xs::xsub_t::xterminated (pipe_t *pipe_)
 {
     fq.terminated (pipe_);
-    if (pipe_->get_protocol () != 1)
+    if (pipe_->get_sp_version () != 1)
         dist.terminated (pipe_);
 }
 
 void xs::xsub_t::xhiccuped (pipe_t *pipe_)
 {
     //  In 0MQ/2.1 protocol there is no subscription forwarding.
-    if (pipe_->get_protocol () == 1)
+    if (pipe_->get_sp_version () == 1)
         return;
 
     //  Send all the cached subscriptions to the new upstream peer.
@@ -104,13 +144,13 @@ int xs::xsub_t::xsend (msg_t *msg_, int flags_)
     }
     int cmd = get_uint16 (data);
     int filter_id = get_uint16 (data + 2);
-    if (cmd != XS_CMD_SUBSCRIBE && cmd != XS_CMD_UNSUBSCRIBE) {
+    if (cmd != SP_PUBSUB_CMD_SUBSCRIBE && cmd != SP_PUBSUB_CMD_UNSUBSCRIBE) {
         errno = EINVAL;
         return -1;
     }
 
     //  Process the subscription.
-    if (cmd == XS_CMD_SUBSCRIBE) {
+    if (cmd == SP_PUBSUB_CMD_SUBSCRIBE) {
         subscriptions_t::iterator it = subscriptions.insert (
            std::make_pair (std::make_pair (filter_id,
            blob_t (data + 4, size - 4)), 0)).first;
@@ -118,7 +158,7 @@ int xs::xsub_t::xsend (msg_t *msg_, int flags_)
         if (it->second == 1)
             return dist.send_to_all (msg_, flags_);
     }
-    else if (cmd == XS_CMD_UNSUBSCRIBE) {
+    else if (cmd == SP_PUBSUB_CMD_UNSUBSCRIBE) {
         subscriptions_t::iterator it = subscriptions.find (
             std::make_pair (filter_id, blob_t (data + 4, size - 4)));
         if (it != subscriptions.end ()) {
@@ -162,7 +202,8 @@ void xs::xsub_t::send_subscription (pipe_t *pipe_, bool subscribe_,
     int rc = msg.init_size (size_ + 4);
     xs_assert (rc == 0);
     unsigned char *data = (unsigned char*) msg.data ();
-    put_uint16 (data, subscribe_ ? XS_CMD_SUBSCRIBE : XS_CMD_UNSUBSCRIBE);
+    put_uint16 (data, subscribe_ ? SP_PUBSUB_CMD_SUBSCRIBE :
+        SP_PUBSUB_CMD_UNSUBSCRIBE);
     put_uint16 (data + 2, filter_id_);
     memcpy (data + 4, data_, size_);
 
diff --git a/src/xsub.hpp b/src/xsub.hpp
index 5bc11c4..fcaf61c 100644
--- a/src/xsub.hpp
+++ b/src/xsub.hpp
@@ -47,6 +47,7 @@ namespace xs
     protected:
 
         //  Overloads of functions from socket_base_t.
+        int xsetsockopt (int option_, const void *optval_, size_t optvallen_);
         void xattach_pipe (xs::pipe_t *pipe_, bool icanhasall_);
         int xsend (xs::msg_t *msg_, int flags_);
         bool xhas_out ();
diff --git a/src/xsurveyor.cpp b/src/xsurveyor.cpp
index 985b6d8..d02ea09 100644
--- a/src/xsurveyor.cpp
+++ b/src/xsurveyor.cpp
@@ -21,11 +21,16 @@
 #include "xsurveyor.hpp"
 #include "err.hpp"
 #include "msg.hpp"
+#include "wire.hpp"
 
 xs::xsurveyor_t::xsurveyor_t (class ctx_t *parent_, uint32_t tid_, int sid_) :
     socket_base_t (parent_, tid_, sid_)
 {
     options.type = XS_XSURVEYOR;
+    options.sp_pattern = SP_SURVEY;
+    options.sp_version = 1;
+    options.sp_role = SP_SURVEY_SURVEYOR;
+    options.sp_complement = SP_SURVEY_RESPONDENT;
 
     //  When the XSURVEYOR socket is close it makes no sense to send any pending
     //  surveys. The responses will be unroutable anyway.
@@ -36,6 +41,34 @@ xs::xsurveyor_t::~xsurveyor_t ()
 {
 }
 
+int xs::xsurveyor_t::xsetsockopt (int option_, const void *optval_,
+    size_t optvallen_)
+{
+    if (option_ != XS_PROTOCOL) {
+        errno = EINVAL;
+        return -1;
+    }
+
+    if (optvallen_ != sizeof (int)) {
+        errno = EINVAL;
+        return -1;
+    }
+
+    if (!optval_) {
+        errno = EFAULT;
+        return -1;
+    }
+
+    int version = *(int *) optval_;
+    if (version != 1) {
+        errno = EINVAL;
+        return -1;
+    }
+
+    options.sp_version = version;
+    return 0;
+}
+
 void xs::xsurveyor_t::xattach_pipe (pipe_t *pipe_, bool icanhasall_)
 {
     xs_assert (pipe_);
diff --git a/src/xsurveyor.hpp b/src/xsurveyor.hpp
index b0c3f9c..e312667 100644
--- a/src/xsurveyor.hpp
+++ b/src/xsurveyor.hpp
@@ -45,6 +45,7 @@ namespace xs
     protected:
 
         //  Overloads of functions from socket_base_t.
+        int xsetsockopt (int option_, const void *optval_, size_t optvallen_);
         void xattach_pipe (xs::pipe_t *pipe_, bool icanhasall_);
         int xsend (xs::msg_t *msg_, int flags_);
         int xrecv (xs::msg_t *msg_, int flags_);