From 7adec2d5fc29036a6ce78c4f4e95f85466cb5d9a Mon Sep 17 00:00:00 2001
From: Alvaro Herrera <alvherre@alvh.no-ip.org>
Date: Fri, 9 Aug 2024 17:55:01 -0400
Subject: [PATCH] libpq: Trace StartupMessage/SSLRequest/GSSENCRequest
 correctly
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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 <postgres@jeltef.nl>
Discussion: https://postgr.es/m/CAGECzQSoPHtZ4xe0raJ6FYSEiPPS+YWXBhOGo+Y1YecLgknF3g@mail.gmail.com
---
 src/interfaces/libpq/fe-trace.c | 55 ++++++++++++++++++++++++++-------
 1 file changed, 43 insertions(+), 12 deletions(-)

diff --git a/src/interfaces/libpq/fe-trace.c b/src/interfaces/libpq/fe-trace.c
index c479ea19c4..c34047a6e4 100644
--- a/src/interfaces/libpq/fe-trace.c
+++ b/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);