libpq: Trace StartupMessage/SSLRequest/GSSENCRequest correctly

libpq tracing via PQtrace would uselessly print the wrong thing for
these types of messages.  With this commit, their type and contents
would be correctly listed.  (This can be verified with PQconnectStart(),
but we don't use that in libpq_pipeline, so I (Álvaro) haven't bothered
to add any tests.)

Author: Jelte Fennema-Nio <[email protected]>
Discussion: https://postgr.es/m/CAGECzQSoPHtZ4xe0raJ6FYSEiPPS+YWXBhOGo+Y1YecLgknF3g@mail.gmail.com

Author: alvherre

src/interfaces/libpq/fe-trace.c

@@ -707,8 +707,12 @@ void
 pqTraceOutputNoTypeByteMessage(PGconn *conn, const char *message)
 {
 	int			length;
+	int			version;
+	bool		regress;
 	int			logCursor = 0;
 
+	regress = (conn->traceFlags & PQTRACE_REGRESS_MODE) != 0;
+
 	if ((conn->traceFlags & PQTRACE_SUPPRESS_TIMESTAMPS) == 0)
 	{
 		char		timestr[128];
@@ -723,19 +727,46 @@ pqTraceOutputNoTypeByteMessage(PGconn *conn, const char *message)
 
 	fprintf(conn->Pfdebug, "F\t%d\t", length);
 
-	switch (length)
+	if (length < 8)
 	{
-		case 16:				/* CancelRequest */
-			fprintf(conn->Pfdebug, "CancelRequest\t");
-			pqTraceOutputInt32(conn->Pfdebug, message, &logCursor, false);
-			pqTraceOutputInt32(conn->Pfdebug, message, &logCursor, false);
-			pqTraceOutputInt32(conn->Pfdebug, message, &logCursor, false);
-			break;
-		case 8:					/* GSSENCRequest or SSLRequest */
-			/* These messages do not reach here. */
-		default:
-			fprintf(conn->Pfdebug, "Unknown message: length is %d", length);
-			break;
+		fprintf(conn->Pfdebug, "Unknown message\n");
+		return;
+	}
+
+	memcpy(&version, message + logCursor, 4);
+	version = (int) pg_ntoh32(version);
+
+	if (version == CANCEL_REQUEST_CODE && length >= 16)
+	{
+		fprintf(conn->Pfdebug, "CancelRequest\t");
+		pqTraceOutputInt16(conn->Pfdebug, message, &logCursor);
+		pqTraceOutputInt16(conn->Pfdebug, message, &logCursor);
+		pqTraceOutputInt32(conn->Pfdebug, message, &logCursor, regress);
+		pqTraceOutputInt32(conn->Pfdebug, message, &logCursor, regress);
+	}
+	else if (version == NEGOTIATE_SSL_CODE)
+	{
+		fprintf(conn->Pfdebug, "SSLRequest\t");
+		pqTraceOutputInt16(conn->Pfdebug, message, &logCursor);
+		pqTraceOutputInt16(conn->Pfdebug, message, &logCursor);
+	}
+	else if (version == NEGOTIATE_GSS_CODE)
+	{
+		fprintf(conn->Pfdebug, "GSSENCRequest\t");
+		pqTraceOutputInt16(conn->Pfdebug, message, &logCursor);
+		pqTraceOutputInt16(conn->Pfdebug, message, &logCursor);
+	}
+	else
+	{
+		fprintf(conn->Pfdebug, "StartupMessage\t");
+		pqTraceOutputInt16(conn->Pfdebug, message, &logCursor);
+		pqTraceOutputInt16(conn->Pfdebug, message, &logCursor);
+		while (message[logCursor] != '\0')
+		{
+			/* XXX should we suppress anything in regress mode? */
+			pqTraceOutputString(conn->Pfdebug, message, &logCursor, false);
+			pqTraceOutputString(conn->Pfdebug, message, &logCursor, false);
+		}
 	}
 
 	fputc('\n', conn->Pfdebug);