Update mc_tcp.cpp

src/gausskernel/cbb/communication/libcomm_core/mc_tcp.cpp

@@ -81,6 +81,27 @@ void mc_tcp_set_keepalive(int fd)
     mc_tcp_setsockopt(fd, IPPROTO_TCP, TCP_KEEPCNT, (char*)&count, sizeof(count));
 }
 
+/*
+function name: mc_tcp_get_peer_name
+description: This function is used to obtain the host IP and port number of the host bound to the specific socket.
+arguments: The first argument is a descriptor to a specified socket.
+				   The second argument is used to store the host IP address bound to the socket determined by the first parameter, in dotted decimal.
+                   The third parameter is used to store the port number bound to a specific socket, in the order of host bytes.
+return value: Return 0 if the function runs successfully.
+					 When the call to the getpeername() function fails：
+					 		1、Return EBADF if the socket argument is not a valid file descriptor.
+					 		2、Return EINVAL if the socket has been shut down.
+				  	 		3、Return ENOTCONN if the socket is not connected or otherwise has not had the peer pre-specified.
+					 		4、Return ENOTSOCK if the socket argument does not refer to a socket.
+					 	 	5、Return EOPNOTSUPP if the operation is not supported for the socket protocol.
+					 		6、Return ENOBUFS if insufficient resources were available in the system to complete the call.
+                     Return -2 when the host IP address belongs to IPv4 type, it fails to convert it to dotted decimal.
+                     Return -3 when the host IP address belongs to IPv6 type, it fails to convert it to dotted decimal.
+                     Return -4 when the error type is not any of the above.
+note: Allocate a certain amount of memory space for the host and port pointers respectively in advance.
+date: 2022/8/9
+contact tel: 18720816902
+*/
 int mc_tcp_get_peer_name(int fd, char* host, int* port)
 {
     struct sockaddr peeraddr = {0};