Fix #440

a. Supress EPERM: on macos the bind will always fail with EPERM when runs in code signing sandbox mode
        even through provide ADDR_ANY and port=0 to require bind a random local endpoint, but on other systems,
        require call bind before connect for UDP sockets.

b. Don't invoke socket.bind for tcp when not require bind network inteface or port explicitly

yasio/io_service.cpp

@@ -695,15 +695,15 @@ void io_transport_kcp::set_primitives()
   io_transport_udp::set_primitives();
   underlaying_write_cb_ = write_cb_;
   write_cb_             = [this](const void* data, int len, const ip::endpoint*, int& error) {
-      int nsent = ::ikcp_send(kcp_, static_cast<const char*>(data), len /*(std::min)(static_cast<int>(kcp_->mss), len)*/);
-      if (nsent > 0)
-      {
-        ::ikcp_flush(kcp_);
-        expire_time_ = 0;
-      }
-      else
-        error = EMSGSIZE; // emit message too long
-      return nsent;
+    int nsent = ::ikcp_send(kcp_, static_cast<const char*>(data), len /*(std::min)(static_cast<int>(kcp_->mss), len)*/);
+    if (nsent > 0)
+    {
+      ::ikcp_flush(kcp_);
+      expire_time_ = 0;
+    }
+    else
+      error = EMSGSIZE; // emit message too long
+    return nsent;
   };
 }
 bool io_transport_kcp::do_write(highp_time_t& wait_duration)
@@ -1225,10 +1225,21 @@ void io_service::do_connect(io_channel* ctx)
     if (yasio__testbits(ctx->properties_, YCF_EXCLUSIVEADDRUSE))
       ctx->socket_->exclusive_address(true);
 
-    if (!yasio__testbits(ctx->properties_, YCM_UDS))
-    {
+    if (!yasio__testbits(ctx->properties_, YCM_UDS) && (!ctx->local_host_.empty() || ctx->local_port_ != 0 || yasio__testbits(ctx->properties_, YCM_UDP)))
+    { // Don't invoke socket.bind for tcp when not require bind network inteface or port explicitly
       auto ifaddr = ctx->local_host_.empty() ? YASIO_ADDR_ANY(ep.af()) : ctx->local_host_.c_str();
       ret         = ctx->socket_->bind(ifaddr, ctx->local_port_);
+      if (ret < 0 && xxsocket::get_last_errno() == EPERM)
+      {
+        /*
+        Supress EPERM: on macos the bind will always fail with EPERM when runs in code signing sandbox mode
+        even through provide ADDR_ANY and port=0 to require bind a random local endpoint, but on other systems,
+        require call bind before connect for UDP sockets.
+        refer issue: https://github.com/yasio/yasio/issues/440
+        */
+        YASIO_KLOGW("bind %s:%u fail", ifaddr, ctx->local_port_);
+        ret = 0;
+      }
     }
 
     if (ret == 0)