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, 163 deletions

diff --git a/src/backend/tcop/fastpath.c b/src/backend/tcop/fastpath.c
index 1b76653caa4..77d17ebca94 100644
--- a/src/backend/tcop/fastpath.c
+++ b/src/backend/tcop/fastpath.c
@@ -58,98 +58,24 @@ struct fp_info
 
 static int16 parse_fcall_arguments(StringInfo msgBuf, struct fp_info *fip,
 								   FunctionCallInfo fcinfo);
-static int16 parse_fcall_arguments_20(StringInfo msgBuf, struct fp_info *fip,
-									  FunctionCallInfo fcinfo);
-
-
-/* ----------------
- *		GetOldFunctionMessage
- *
- * In pre-3.0 protocol, there is no length word on the message, so we have
- * to have code that understands the message layout to absorb the message
- * into a buffer.  We want to do this before we start execution, so that
- * we do not lose sync with the frontend if there's an error.
- *
- * The caller should already have initialized buf to empty.
- * ----------------
- */
-int
-GetOldFunctionMessage(StringInfo buf)
-{
-	int32		ibuf;
-	int			nargs;
-
-	/* Dummy string argument */
-	if (pq_getstring(buf))
-		return EOF;
-	/* Function OID */
-	if (pq_getbytes((char *) &ibuf, 4))
-		return EOF;
-	appendBinaryStringInfo(buf, (char *) &ibuf, 4);
-	/* Number of arguments */
-	if (pq_getbytes((char *) &ibuf, 4))
-		return EOF;
-	appendBinaryStringInfo(buf, (char *) &ibuf, 4);
-	nargs = pg_ntoh32(ibuf);
-	/* For each argument ... */
-	while (nargs-- > 0)
-	{
-		int			argsize;
-
-		/* argsize */
-		if (pq_getbytes((char *) &ibuf, 4))
-			return EOF;
-		appendBinaryStringInfo(buf, (char *) &ibuf, 4);
-		argsize = pg_ntoh32(ibuf);
-		if (argsize < -1)
-		{
-			/* FATAL here since no hope of regaining message sync */
-			ereport(FATAL,
-					(errcode(ERRCODE_PROTOCOL_VIOLATION),
-					 errmsg("invalid argument size %d in function call message",
-							argsize)));
-		}
-		/* and arg contents */
-		if (argsize > 0)
-		{
-			/* Allocate space for arg */
-			enlargeStringInfo(buf, argsize);
-			/* And grab it */
-			if (pq_getbytes(buf->data + buf->len, argsize))
-				return EOF;
-			buf->len += argsize;
-			/* Place a trailing null per StringInfo convention */
-			buf->data[buf->len] = '\0';
-		}
-	}
-	return 0;
-}
 
 /* ----------------
  *		SendFunctionResult
- *
- * Note: although this routine doesn't check, the format had better be 1
- * (binary) when talking to a pre-3.0 client.
  * ----------------
  */
 static void
 SendFunctionResult(Datum retval, bool isnull, Oid rettype, int16 format)
 {
-	bool		newstyle = (PG_PROTOCOL_MAJOR(FrontendProtocol) >= 3);
 	StringInfoData buf;
 
 	pq_beginmessage(&buf, 'V');
 
 	if (isnull)
 	{
-		if (newstyle)
-			pq_sendint32(&buf, -1);
+		pq_sendint32(&buf, -1);
 	}
 	else
 	{
-		if (!newstyle)
-			pq_sendbyte(&buf, 'G');
-
 		if (format == 0)
 		{
 			Oid			typoutput;
@@ -180,9 +106,6 @@ SendFunctionResult(Datum retval, bool isnull, Oid rettype, int16 format)
 					 errmsg("unsupported format code: %d", format)));
 	}
 
-	if (!newstyle)
-		pq_sendbyte(&buf, '0');
-
 	pq_endmessage(&buf);
 }
 
@@ -288,9 +211,6 @@ HandleFunctionRequest(StringInfo msgBuf)
 	/*
 	 * Begin parsing the buffer contents.
 	 */
-	if (PG_PROTOCOL_MAJOR(FrontendProtocol) < 3)
-		(void) pq_getmsgstring(msgBuf); /* dummy string */
-
 	fid = (Oid) pq_getmsgint(msgBuf, 4);	/* function oid */
 
 	/*
@@ -334,10 +254,7 @@ HandleFunctionRequest(StringInfo msgBuf)
 	 */
 	InitFunctionCallInfoData(*fcinfo, &fip->flinfo, 0, InvalidOid, NULL, NULL);
 
-	if (PG_PROTOCOL_MAJOR(FrontendProtocol) >= 3)
-		rformat = parse_fcall_arguments(msgBuf, fip, fcinfo);
-	else
-		rformat = parse_fcall_arguments_20(msgBuf, fip, fcinfo);
+	rformat = parse_fcall_arguments(msgBuf, fip, fcinfo);
 
 	/* Verify we reached the end of the message where expected. */
 	pq_getmsgend(msgBuf);
@@ -533,81 +450,3 @@ parse_fcall_arguments(StringInfo msgBuf, struct fp_info *fip,
 	/* Return result format code */
 	return (int16) pq_getmsgint(msgBuf, 2);
 }
-
-/*
- * Parse function arguments in a 2.0 protocol message
- *
- * Argument values are loaded into *fcinfo, and the desired result format
- * is returned.
- */
-static int16
-parse_fcall_arguments_20(StringInfo msgBuf, struct fp_info *fip,
-						 FunctionCallInfo fcinfo)
-{
-	int			nargs;
-	int			i;
-	StringInfoData abuf;
-
-	nargs = pq_getmsgint(msgBuf, 4);	/* # of arguments */
-
-	if (fip->flinfo.fn_nargs != nargs || nargs > FUNC_MAX_ARGS)
-		ereport(ERROR,
-				(errcode(ERRCODE_PROTOCOL_VIOLATION),
-				 errmsg("function call message contains %d arguments but function requires %d",
-						nargs, fip->flinfo.fn_nargs)));
-
-	fcinfo->nargs = nargs;
-
-	initStringInfo(&abuf);
-
-	/*
-	 * Copy supplied arguments into arg vector.  In protocol 2.0 these are
-	 * always assumed to be supplied in binary format.
-	 *
-	 * Note: although the original protocol 2.0 code did not have any way for
-	 * the frontend to specify a NULL argument, we now choose to interpret
-	 * length == -1 as meaning a NULL.
-	 */
-	for (i = 0; i < nargs; ++i)
-	{
-		int			argsize;
-		Oid			typreceive;
-		Oid			typioparam;
-
-		getTypeBinaryInputInfo(fip->argtypes[i], &typreceive, &typioparam);
-
-		argsize = pq_getmsgint(msgBuf, 4);
-		if (argsize == -1)
-		{
-			fcinfo->args[i].isnull = true;
-			fcinfo->args[i].value = OidReceiveFunctionCall(typreceive, NULL,
-														   typioparam, -1);
-			continue;
-		}
-		fcinfo->args[i].isnull = false;
-		if (argsize < 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_PROTOCOL_VIOLATION),
-					 errmsg("invalid argument size %d in function call message",
-							argsize)));
-
-		/* Reset abuf to empty, and insert raw data into it */
-		resetStringInfo(&abuf);
-		appendBinaryStringInfo(&abuf,
-							   pq_getmsgbytes(msgBuf, argsize),
-							   argsize);
-
-		fcinfo->args[i].value = OidReceiveFunctionCall(typreceive, &abuf,
-													   typioparam, -1);
-
-		/* Trouble if it didn't eat the whole buffer */
-		if (abuf.cursor != abuf.len)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_BINARY_REPRESENTATION),
-					 errmsg("incorrect binary data format in function argument %d",
-							i + 1)));
-	}
-
-	/* Desired result format is always binary in protocol 2.0 */
-	return 1;
-}