Refactor sendAuthRequest.

This way sendAuthRequest doesn't need to know the details of all the
different authentication methods. This is in preparation for adding SCRAM
authentication, which will add yet another authentication request message
type, with different payload.

Reviewed-By: Michael Paquier
Discussion: <CAB7nPqQvO4sxLFeS9D+NM3wpy08ieZdAj_6e117MQHZAfxBFsg@mail.gmail.com>

src/backend/libpq/auth.c

@@ -36,7 +36,8 @@
  * Global authentication functions
  *----------------------------------------------------------------
  */
-static void sendAuthRequest(Port *port, AuthRequest areq);
+static void sendAuthRequest(Port *port, AuthRequest areq, char *extradata,
+				int extralen);
 static void auth_failed(Port *port, int status, char *logdetail);
 static char *recv_password_packet(Port *port);
 static int	recv_and_check_password_packet(Port *port, char **logdetail);
@@ -498,7 +499,7 @@ ClientAuthentication(Port *port)
 
 		case uaGSS:
 #ifdef ENABLE_GSS
-			sendAuthRequest(port, AUTH_REQ_GSS);
+			sendAuthRequest(port, AUTH_REQ_GSS, NULL, 0);
 			status = pg_GSS_recvauth(port);
 #else
 			Assert(false);
@@ -507,7 +508,7 @@ ClientAuthentication(Port *port)
 
 		case uaSSPI:
 #ifdef ENABLE_SSPI
-			sendAuthRequest(port, AUTH_REQ_SSPI);
+			sendAuthRequest(port, AUTH_REQ_SSPI, NULL, 0);
 			status = pg_SSPI_recvauth(port);
 #else
 			Assert(false);
@@ -531,12 +532,13 @@ ClientAuthentication(Port *port)
 				ereport(FATAL,
 						(errcode(ERRCODE_INVALID_AUTHORIZATION_SPECIFICATION),
 						 errmsg("MD5 authentication is not supported when \"db_user_namespace\" is enabled")));
-			sendAuthRequest(port, AUTH_REQ_MD5);
+			/* include the salt to use for computing the response */
+			sendAuthRequest(port, AUTH_REQ_MD5, port->md5Salt, 4);
 			status = recv_and_check_password_packet(port, &logdetail);
 			break;
 
 		case uaPassword:
-			sendAuthRequest(port, AUTH_REQ_PASSWORD);
+			sendAuthRequest(port, AUTH_REQ_PASSWORD, NULL, 0);
 			status = recv_and_check_password_packet(port, &logdetail);
 			break;
 
@@ -583,7 +585,7 @@ ClientAuthentication(Port *port)
 		(*ClientAuthentication_hook) (port, status);
 
 	if (status == STATUS_OK)
-		sendAuthRequest(port, AUTH_REQ_OK);
+		sendAuthRequest(port, AUTH_REQ_OK, NULL, 0);
 	else
 		auth_failed(port, status, logdetail);
 }
@@ -593,7 +595,7 @@ ClientAuthentication(Port *port)
  * Send an authentication request packet to the frontend.
  */
 static void
-sendAuthRequest(Port *port, AuthRequest areq)
+sendAuthRequest(Port *port, AuthRequest areq, char *extradata, int extralen)
 {
 	StringInfoData buf;
 
@@ -601,28 +603,8 @@ sendAuthRequest(Port *port, AuthRequest areq)
 
 	pq_beginmessage(&buf, 'R');
 	pq_sendint(&buf, (int32) areq, sizeof(int32));
-
-	/* Add the salt for encrypted passwords. */
-	if (areq == AUTH_REQ_MD5)
-		pq_sendbytes(&buf, port->md5Salt, 4);
-
-#if defined(ENABLE_GSS) || defined(ENABLE_SSPI)
-
-	/*
-	 * Add the authentication data for the next step of the GSSAPI or SSPI
-	 * negotiation.
-	 */
-	else if (areq == AUTH_REQ_GSS_CONT)
-	{
-		if (port->gss->outbuf.length > 0)
-		{
-			elog(DEBUG4, "sending GSS token of length %u",
-				 (unsigned int) port->gss->outbuf.length);
-
-			pq_sendbytes(&buf, port->gss->outbuf.value, port->gss->outbuf.length);
-		}
-	}
-#endif
+	if (extralen > 0)
+		pq_sendbytes(&buf, extradata, extralen);
 
 	pq_endmessage(&buf);
 
@@ -934,7 +916,8 @@ pg_GSS_recvauth(Port *port)
 			elog(DEBUG4, "sending GSS response token of length %u",
 				 (unsigned int) port->gss->outbuf.length);
 
-			sendAuthRequest(port, AUTH_REQ_GSS_CONT);
+			sendAuthRequest(port, AUTH_REQ_GSS_CONT,
+							port->gss->outbuf.value, port->gss->outbuf.length);
 
 			gss_release_buffer(&lmin_s, &port->gss->outbuf);
 		}
@@ -1179,7 +1162,8 @@ pg_SSPI_recvauth(Port *port)
 			port->gss->outbuf.length = outbuf.pBuffers[0].cbBuffer;
 			port->gss->outbuf.value = outbuf.pBuffers[0].pvBuffer;
 
-			sendAuthRequest(port, AUTH_REQ_GSS_CONT);
+			sendAuthRequest(port, AUTH_REQ_GSS_CONT,
+							port->gss->outbuf.value, port->gss->outbuf.length);
 
 			FreeContextBuffer(outbuf.pBuffers[0].pvBuffer);
 		}
@@ -1807,7 +1791,7 @@ pam_passwd_conv_proc(int num_msg, const struct pam_message ** msg,
 					 * let's go ask the client to send a password, which we
 					 * then stuff into PAM.
 					 */
-					sendAuthRequest(pam_port_cludge, AUTH_REQ_PASSWORD);
+					sendAuthRequest(pam_port_cludge, AUTH_REQ_PASSWORD, NULL, 0);
 					passwd = recv_password_packet(pam_port_cludge);
 					if (passwd == NULL)
 					{
@@ -2137,7 +2121,7 @@ CheckLDAPAuth(Port *port)
 	if (port->hba->ldapport == 0)
 		port->hba->ldapport = LDAP_PORT;
 
-	sendAuthRequest(port, AUTH_REQ_PASSWORD);
+	sendAuthRequest(port, AUTH_REQ_PASSWORD, NULL, 0);
 
 	passwd = recv_password_packet(port);
 	if (passwd == NULL)
@@ -2497,7 +2481,7 @@ CheckRADIUSAuth(Port *port)
 		identifier = port->hba->radiusidentifier;
 
 	/* Send regular password request to client, and get the response */
-	sendAuthRequest(port, AUTH_REQ_PASSWORD);
+	sendAuthRequest(port, AUTH_REQ_PASSWORD, NULL, 0);
 
 	passwd = recv_password_packet(port);
 	if (passwd == NULL)