merging some things from Ryan C. Gordon (icculus):

enet_socket_connect() shouldn't fail with non-blocking sockets.
Removed unused variable.
Sanity check for possible NULL dereference reported by clang's static…analysis.
Added an interface to shutdown().
Fixed typo in the comments.

include/enet/enet.h

@@ -55,6 +55,13 @@ typedef enum _ENetSocketOption
    ENET_SOCKOPT_SNDTIMEO  = 7
 } ENetSocketOption;
 
+typedef enum _ENetSocketShutdown
+{
+    ENET_SOCKET_SHUTDOWN_READ       = 0,
+    ENET_SOCKET_SHUTDOWN_WRITE      = 1,
+    ENET_SOCKET_SHUTDOWN_READ_WRITE = 2
+} ENetSocketShutdown;
+
 enum
 {
    ENET_HOST_ANY       = 0,            /**< specifies the default server host */
@@ -460,6 +467,7 @@ ENET_API int        enet_socket_send (ENetSocket, const ENetAddress *, const ENe
 ENET_API int        enet_socket_receive (ENetSocket, ENetAddress *, ENetBuffer *, size_t);
 ENET_API int        enet_socket_wait (ENetSocket, enet_uint32 *, enet_uint32);
 ENET_API int        enet_socket_set_option (ENetSocket, ENetSocketOption, int);
+ENET_API int        enet_socket_shutdown (ENetSocket, ENetSocketShutdown);
 ENET_API void       enet_socket_destroy (ENetSocket);
 ENET_API int        enet_socketset_select (ENetSocket, ENetSocketSet *, ENetSocketSet *, enet_uint32);
 

peer.c

@@ -25,7 +25,7 @@
     the mean round trip time measured over the interval, then the throttle probability
     is decreased to limit traffic by an amount specified in the deceleration parameter, which
     is a ratio to the ENET_PEER_PACKET_THROTTLE_SCALE constant.  When the throttle has
-    a value of ENET_PEER_PACKET_THROTTLE_SCALE, on unreliable packets are dropped by 
+    a value of ENET_PEER_PACKET_THROTTLE_SCALE, no unreliable packets are dropped by 
     ENet, and so 100% of all unreliable packets will be sent.  When the throttle has a
     value of 0, all unreliable packets are dropped by ENet, and so 0% of all unreliable
     packets will be sent.  Intermediate values for the throttle represent intermediate
@@ -751,7 +751,6 @@ enet_peer_dispatch_incoming_unreliable_commands (ENetPeer * peer, ENetChannel *
 void
 enet_peer_dispatch_incoming_reliable_commands (ENetPeer * peer, ENetChannel * channel)
 {
-    enet_uint16 oldReliableSequenceNumber = channel -> incomingReliableSequenceNumber;
     ENetListIterator currentCommand;
 
     for (currentCommand = enet_list_begin (& channel -> incomingReliableCommands);

protocol.c

@@ -210,6 +210,9 @@ enet_protocol_remove_sent_reliable_command (ENetPeer * peer, enet_uint16 reliabl
        wasSent = 0;
     }
 
+    if (outgoingCommand == NULL)
+      return ENET_PROTOCOL_COMMAND_NONE;
+
     if (channelID < peer -> channelCount)
     {
        ENetChannel * channel = & peer -> channels [channelID];

unix.c

@@ -254,6 +254,7 @@ int
 enet_socket_connect (ENetSocket socket, const ENetAddress * address)
 {
     struct sockaddr_in sin;
+    int result;
 
     memset (& sin, 0, sizeof (struct sockaddr_in));
 
@@ -261,7 +262,11 @@ enet_socket_connect (ENetSocket socket, const ENetAddress * address)
     sin.sin_port = ENET_HOST_TO_NET_16 (address -> port);
     sin.sin_addr.s_addr = address -> host;
 
-    return connect (socket, (struct sockaddr *) & sin, sizeof (struct sockaddr_in));
+    result = connect (socket, (struct sockaddr *) & sin, sizeof (struct sockaddr_in));
+    if (result == -1 && errno == EINPROGRESS)
+      return 0;
+
+    return result;
 }
 
 ENetSocket
@@ -287,6 +292,12 @@ enet_socket_accept (ENetSocket socket, ENetAddress * address)
     return result;
 } 
     
+int
+enet_socket_shutdown (ENetSocket socket, ENetSocketShutdown how)
+{
+    return shutdown (socket, (int) how);
+}
+
 void
 enet_socket_destroy (ENetSocket socket)
 {

win32.c

@@ -184,6 +184,7 @@ int
 enet_socket_connect (ENetSocket socket, const ENetAddress * address)
 {
     struct sockaddr_in sin;
+    int result;
 
     memset (& sin, 0, sizeof (struct sockaddr_in));
 
@@ -191,7 +192,11 @@ enet_socket_connect (ENetSocket socket, const ENetAddress * address)
     sin.sin_port = ENET_HOST_TO_NET_16 (address -> port);
     sin.sin_addr.s_addr = address -> host;
 
-    return connect (socket, (struct sockaddr *) & sin, sizeof (struct sockaddr_in)) == SOCKET_ERROR ? -1 : 0;
+    result = connect (socket, (struct sockaddr *) & sin, sizeof (struct sockaddr_in));
+    if (result == SOCKET_ERROR && WSAGetLastError () != EWOULDBLOCK)
+      return -1;
+
+    return 0;
 }
 
 ENetSocket
@@ -217,6 +222,12 @@ enet_socket_accept (ENetSocket socket, ENetAddress * address)
     return result;
 }
 
+int
+enet_socket_shutdown (ENetSocket socket, ENetSocketShutdown how)
+{
+    return shutdown (socket, (int) how) == SOCKET_ERROR ? -1 : 0;
+}
+
 void
 enet_socket_destroy (ENetSocket socket)
 {