Problem: unnecessary non-const variables

Solution: add const

src/socks.cpp

@@ -166,14 +166,14 @@ void zmq::socks_request_encoder_t::encode (const socks_request_t &req)
 
     const int rc = getaddrinfo (req.hostname.c_str (), NULL, &hints, &res);
     if (rc == 0 && res->ai_family == AF_INET) {
-        struct sockaddr_in *sockaddr_in =
-          reinterpret_cast<struct sockaddr_in *> (res->ai_addr);
+        const struct sockaddr_in *sockaddr_in =
+          reinterpret_cast<const struct sockaddr_in *> (res->ai_addr);
         *ptr++ = 0x01;
         memcpy (ptr, &sockaddr_in->sin_addr, 4);
         ptr += 4;
     } else if (rc == 0 && res->ai_family == AF_INET6) {
-        struct sockaddr_in6 *sockaddr_in6 =
-          reinterpret_cast<struct sockaddr_in6 *> (res->ai_addr);
+        const struct sockaddr_in6 *sockaddr_in6 =
+          reinterpret_cast<const struct sockaddr_in6 *> (res->ai_addr);
         *ptr++ = 0x04;
         memcpy (ptr, &sockaddr_in6->sin6_addr, 16);
         ptr += 16;

src/stream_engine.cpp

@@ -1110,12 +1110,14 @@ int zmq::stream_engine_t::process_heartbeat_message (msg_t *msg_)
 
 int zmq::stream_engine_t::process_command_message (msg_t *msg_)
 {
-    uint8_t cmd_name_size = *(static_cast<uint8_t *> (msg_->data ()));
+    const uint8_t cmd_name_size =
+      *(static_cast<const uint8_t *> (msg_->data ()));
     //  Malformed command
     if (msg_->size () < cmd_name_size + sizeof (cmd_name_size))
         return -1;
 
-    uint8_t *cmd_name = (static_cast<uint8_t *> (msg_->data ())) + 1;
+    const uint8_t *cmd_name =
+      (static_cast<const uint8_t *> (msg_->data ())) + 1;
     if (cmd_name_size == 4
         && (memcmp (cmd_name, "PING", cmd_name_size) == 0
             || memcmp (cmd_name, "PONG", cmd_name_size) == 0))

src/tcp_connecter.cpp

@@ -262,7 +262,7 @@ int zmq::tcp_connecter_t::open ()
         return -1;
     }
     zmq_assert (addr->resolved.tcp_addr != NULL);
-    tcp_address_t *const tcp_addr = addr->resolved.tcp_addr;
+    const tcp_address_t *const tcp_addr = addr->resolved.tcp_addr;
 
     //  Create the socket.
     s = open_socket (tcp_addr->family (), SOCK_STREAM, IPPROTO_TCP);

src/udp_engine.cpp

@@ -285,14 +285,15 @@ void zmq::udp_engine_t::terminate ()
 
 void zmq::udp_engine_t::sockaddr_to_msg (zmq::msg_t *msg, sockaddr_in *addr)
 {
-    char *name = inet_ntoa (addr->sin_addr);
+    const char *const name = inet_ntoa (addr->sin_addr);
 
     char port[6];
     sprintf (port, "%d", static_cast<int> (ntohs (addr->sin_port)));
 
-    int size = static_cast<int> (strlen (name))
-               + static_cast<int> (strlen (port)) + 1 + 1; //  Colon + NULL
-    int rc = msg->init_size (size);
+    const int size = static_cast<int> (strlen (name))
+                     + static_cast<int> (strlen (port)) + 1
+                     + 1; //  Colon + NULL
+    const int rc = msg->init_size (size);
     errno_assert (rc == 0);
     msg->set_flags (msg_t::more);
     char *address = static_cast<char *> (msg->data ());
@@ -472,7 +473,8 @@ void zmq::udp_engine_t::in_event ()
         body_size = nbytes;
         body_offset = 0;
     } else {
-        char *group_buffer = reinterpret_cast<char *> (in_buffer) + 1;
+        const char *group_buffer =
+          reinterpret_cast<const char *> (in_buffer) + 1;
         int group_size = in_buffer[0];
 
         rc = msg.init_size (group_size);

src/xpub.cpp

@@ -89,7 +89,8 @@ void zmq::xpub_t::xread_activated (pipe_t *pipe_)
     msg_t sub;
     while (pipe_->read (&sub)) {
         //  Apply the subscription to the trie
-        unsigned char *const data = static_cast<unsigned char *> (sub.data ());
+        const unsigned char *const data =
+          static_cast<const unsigned char *> (sub.data ());
         const size_t size = sub.size ();
         metadata_t *metadata = sub.metadata ();
         if (size > 0 && (*data == 0 || *data == 1)) {

src/zap_client.cpp

@@ -186,7 +186,7 @@ int zap_client_t::receive_and_process_zap_reply ()
     }
 
     //  Status code frame, only 200, 300, 400 and 500 are valid status codes
-    char *status_code_data = static_cast<char *> (msg[3].data ());
+    const char *status_code_data = static_cast<const char *> (msg[3].data ());
     if (msg[3].size () != 3 || status_code_data[0] < '2'
         || status_code_data[0] > '5' || status_code_data[1] != '0'
         || status_code_data[2] != '0') {

src/zmq.cpp

@@ -545,7 +545,7 @@ int zmq_recviov (void *s_, iovec *a_, size_t *count_, int flags_)
         memcpy (a_[i].iov_base, static_cast<char *> (zmq_msg_data (&msg)),
                 a_[i].iov_len);
         // Assume zmq_socket ZMQ_RVCMORE is properly set.
-        zmq::msg_t *p_msg = reinterpret_cast<zmq::msg_t *> (&msg);
+        const zmq::msg_t *p_msg = reinterpret_cast<const zmq::msg_t *> (&msg);
         recvmore = p_msg->flags () & zmq::msg_t::more;
         rc = zmq_msg_close (&msg);
         errno_assert (rc == 0);
@@ -678,7 +678,8 @@ const char *zmq_msg_group (zmq_msg_t *msg_)
 
 const char *zmq_msg_gets (const zmq_msg_t *msg_, const char *property_)
 {
-    zmq::metadata_t *metadata = ((zmq::msg_t *) msg_)->metadata ();
+    const zmq::metadata_t *metadata =
+      reinterpret_cast<const zmq::msg_t *> (msg_)->metadata ();
     const char *value = NULL;
     if (metadata)
         value = metadata->get (std::string (property_));
@@ -1355,7 +1356,7 @@ int zmq_socket_get_peer_state (void *s_,
                                const void *routing_id_,
                                size_t routing_id_size_)
 {
-    zmq::socket_base_t *s = as_socket_base_t (s_);
+    const zmq::socket_base_t *const s = as_socket_base_t (s_);
     if (!s)
         return -1;