Remove server and libpq support for old FE/BE protocol version 2.

Protocol version 3 was introduced in PostgreSQL 7.4. There shouldn't be
many clients or servers left out there without version 3 support. But as
a courtesy, I kept just enough of the old protocol support that we can
still send the "unsupported protocol version" error in v2 format, so that
old clients can display the message properly. Likewise, libpq still
understands v2 ErrorResponse messages when establishing a connection.

The impetus to do this now is that I'm working on a patch to COPY
FROM, to always prefetch some data. We cannot do that safely with the
old protocol, because it requires parsing the input one byte at a time
to detect the end-of-copy marker.

Reviewed-by: Tom Lane, Alvaro Herrera, John Naylor
Discussion: https://www.postgresql.org/message-id/9ec25819-0a8a-d51a-17dc-4150bb3cca3b%40iki.fi

1 files changed, 2 insertions, 6 deletions

diff --git a/src/interfaces/libpq/fe-auth.c b/src/interfaces/libpq/fe-auth.c
index 168b3df52bf..e8062647e60 100644
--- a/src/interfaces/libpq/fe-auth.c
+++ b/src/interfaces/libpq/fe-auth.c
@@ -579,7 +579,7 @@ pg_SASL_init(PGconn *conn, int payloadlen)
 	/*
 	 * Build a SASLInitialResponse message, and send it.
 	 */
-	if (pqPutMsgStart('p', true, conn))
+	if (pqPutMsgStart('p', conn))
 		goto error;
 	if (pqPuts(selected_mechanism, conn))
 		goto error;
@@ -798,11 +798,7 @@ pg_password_sendauth(PGconn *conn, const char *password, AuthRequest areq)
 		default:
 			return STATUS_ERROR;
 	}
-	/* Packet has a message type as of protocol 3.0 */
-	if (PG_PROTOCOL_MAJOR(conn->pversion) >= 3)
-		ret = pqPacketSend(conn, 'p', pwd_to_send, strlen(pwd_to_send) + 1);
-	else
-		ret = pqPacketSend(conn, 0, pwd_to_send, strlen(pwd_to_send) + 1);
+	ret = pqPacketSend(conn, 'p', pwd_to_send, strlen(pwd_to_send) + 1);
 	if (crypt_pwd)
 		free(crypt_pwd);
 	return ret;