ZMQ_MAXMSGSIZE option added

The new option allows user to guard against peers sending
oversized messages. Connection to peer sending oversized message
is dropped.
Signed-off-by: Martin Sustrik <sustrik@250bpm.com>

doc/zmq_getsockopt.txt

@@ -311,6 +311,20 @@ Default value:: 100
 Applicable socket types:: all, only for connection-oriented transports
 
 
+ZMQ_MAXMSGSIZE: Maximum acceptable inbound message size
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The options shall retrieve limit for the inbound messages. If a peer sends
+a message larger than ZMQ_MAXMSGSIZE it is disconnected. Value of -1 means
+'no limit'.
+
+[horizontal]
+Option value type:: int64_t
+Option value unit:: bytes
+Default value:: -1
+Applicable socket types:: all
+
+
 ZMQ_FD: Retrieve file descriptor associated with the socket
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 The 'ZMQ_FD' option shall retrieve the file descriptor associated with the

doc/zmq_setsockopt.txt

@@ -319,6 +319,18 @@ Option value unit:: connections
 Default value:: 100
 Applicable socket types:: all, only for connection-oriented transports.
 
+ZMQ_MAXMSGSIZE: Maximum acceptable inbound message size
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Limits the size of the inbound message. If a peer sends a message larger than
+ZMQ_MAXMSGSIZE it is disconnected. Value of -1 means 'no limit'.
+
+[horizontal]
+Option value type:: int64_t
+Option value unit:: bytes
+Default value:: -1
+Applicable socket types:: all
+
 
 RETURN VALUE
 ------------

include/zmq.h

@@ -204,6 +204,7 @@ ZMQ_EXPORT int zmq_term (void *context);
 #define ZMQ_BACKLOG 19
 #define ZMQ_RECOVERY_IVL_MSEC 20   /*  opt. recovery time, reconcile in 3.x   */
 #define ZMQ_RECONNECT_IVL_MAX 21
+#define ZMQ_MAXMSGSIZE 22
     
 /*  Send/recv options.                                                        */
 #define ZMQ_NOBLOCK 1

src/decoder.cpp

@@ -25,9 +25,10 @@
 #include "wire.hpp"
 #include "err.hpp"
 
-zmq::decoder_t::decoder_t (size_t bufsize_) :
+zmq::decoder_t::decoder_t (size_t bufsize_, int64_t maxmsgsize_) :
     decoder_base_t <decoder_t> (bufsize_),
-    destination (NULL)
+    destination (NULL),
+    maxmsgsize (maxmsgsize_)
 {
     zmq_msg_init (&in_progress);
 
@@ -63,7 +64,13 @@ bool zmq::decoder_t::one_byte_size_ready ()
         //  in_progress is initialised at this point so in theory we should
         //  close it before calling zmq_msg_init_size, however, it's a 0-byte
         //  message and thus we can treat it as uninitialised...
-        int rc = zmq_msg_init_size (&in_progress, *tmpbuf - 1);
+        int rc;
+        if (maxmsgsize >= 0 && (int64_t) (*tmpbuf - 1) > maxmsgsize) {
+            rc = -1;
+            errno = ENOMEM;
+        }
+        else
+            rc = zmq_msg_init_size (&in_progress, *tmpbuf - 1);
         if (rc != 0 && errno == ENOMEM) {
             rc = zmq_msg_init (&in_progress);
             errno_assert (rc == 0);
@@ -92,7 +99,13 @@ bool zmq::decoder_t::eight_byte_size_ready ()
     //  in_progress is initialised at this point so in theory we should
     //  close it before calling zmq_msg_init_size, however, it's a 0-byte
     //  message and thus we can treat it as uninitialised...
-    int rc = zmq_msg_init_size (&in_progress, size - 1);
+    int rc;
+    if (maxmsgsize >= 0 && (int64_t) (size - 1) > maxmsgsize) {
+        rc = -1;
+        errno = ENOMEM;
+    }
+    else
+        rc = zmq_msg_init_size (&in_progress, size - 1);
     if (rc != 0 && errno == ENOMEM) {
         rc = zmq_msg_init (&in_progress);
         errno_assert (rc == 0);

src/decoder.hpp

@@ -26,6 +26,7 @@
 #include <algorithm>
 
 #include "err.hpp"
+#include "stdint.hpp"
 
 #include "../include/zmq.h"
 
@@ -180,7 +181,7 @@ namespace zmq
     {
     public:
 
-        decoder_t (size_t bufsize_);
+        decoder_t (size_t bufsize_, int64_t maxmsgsize_);
         ~decoder_t ();
 
         void set_inout (struct i_inout *destination_);
@@ -196,6 +197,8 @@ namespace zmq
         unsigned char tmpbuf [8];
         ::zmq_msg_t in_progress;
 
+        int64_t maxmsgsize;
+
         decoder_t (const decoder_t&);
         void operator = (const decoder_t&);
     };

src/options.cpp

@@ -39,6 +39,7 @@ zmq::options_t::options_t () :
     reconnect_ivl (100),
     reconnect_ivl_max (0),
     backlog (100),
+    maxmsgsize (-1),
     requires_in (false),
     requires_out (false),
     immediate_connect (true)
@@ -182,6 +183,14 @@ int zmq::options_t::setsockopt (int option_, const void *optval_,
         backlog = *((int*) optval_);
         return 0;
 
+    case ZMQ_MAXMSGSIZE:
+        if (optvallen_ != sizeof (int64_t)) {
+            errno = EINVAL;
+            return -1;
+        }
+        maxmsgsize = *((int64_t*) optval_);
+        return 0;
+
     }
 
     errno = EINVAL;
@@ -328,6 +337,15 @@ int zmq::options_t::getsockopt (int option_, void *optval_, size_t *optvallen_)
         *optvallen_ = sizeof (int);
         return 0;
 
+    case ZMQ_MAXMSGSIZE:
+        if (*optvallen_ < sizeof (int64_t)) {
+            errno = EINVAL;
+            return -1;
+        }
+        *((int64_t*) optval_) = maxmsgsize;
+        *optvallen_ = sizeof (int64_t);
+        return 0;
+
     }
 
     errno = EINVAL;

src/options.hpp

@@ -69,6 +69,9 @@ namespace zmq
         //  Maximum backlog for pending connections.
         int backlog;
 
+        //  Maximal size of message to handle.
+        int64_t maxmsgsize;
+
         //  These options are never set by the user directly. Instead they are
         //  provided by the specific socket type.
         bool requires_in;

src/pgm_receiver.cpp

@@ -211,7 +211,8 @@ void zmq::pgm_receiver_t::in_event ()
             it->second.joined = true;
 
             //  Create and connect decoder for the peer.
-            it->second.decoder = new (std::nothrow) decoder_t (0);
+            it->second.decoder = new (std::nothrow) decoder_t (0,
+                options.maxmsgsize);
             alloc_assert (it->second.decoder);
             it->second.decoder->set_inout (inout);
         }

src/zmq_engine.cpp

@@ -35,7 +35,7 @@
 zmq::zmq_engine_t::zmq_engine_t (fd_t fd_, const options_t &options_) :
     inpos (NULL),
     insize (0),
-    decoder (in_batch_size),
+    decoder (in_batch_size, options_.maxmsgsize),
     outpos (NULL),
     outsize (0),
     encoder (out_batch_size),