Fix tracing of BackendKeyData and CancelRequest

BackendKeyData length was increased from 4 bytes to a variable-length
length (up to 256 bytes) in a460251f0a. However, pqTrace still traces
it as a 4 bytes key, leading to a "mismatched message length" warning
message. The same issue impacts the tracing of CancelRequest.

This patch fixes the issue by using pqTraceOutputNchar instead of
pqTraceOutputInt32 in both cases.

Author: Anthonin Bonnefoy <anthonin.bonnefoy@datadoghq.com>
Discussion: https://www.postgresql.org/message-id/CAO6_Xqo6gTv9=76H=k2qDRFU+KHuBiY2S=bQynEr6J8gS7L6xA@mail.gmail.com
Backpatch-through: 18

diff --git a/src/interfaces/libpq/fe-trace.c b/src/interfaces/libpq/fe-trace.c
index c348b08c39b63ebf9b75c00a50f44a8aaeb965f9..2901fa5b451b5928bf64b375addcc0456f73834a 100644 (file)
--- a/src/interfaces/libpq/fe-trace.c
+++ b/src/interfaces/libpq/fe-trace.c
@@ -452,11 +452,12 @@ pqTraceOutput_CopyOutResponse(FILE *f, const char *message, int *cursor)
 }
 
 static void
-pqTraceOutput_BackendKeyData(FILE *f, const char *message, int *cursor, bool regress)
+pqTraceOutput_BackendKeyData(FILE *f, const char *message, int *cursor, int length,
+                                                        bool regress)
 {
        fprintf(f, "BackendKeyData\t");
        pqTraceOutputInt32(f, message, cursor, regress);
-       pqTraceOutputInt32(f, message, cursor, regress);
+       pqTraceOutputNchar(f, length - *cursor + 1, message, cursor, regress);
 }
 
 static void
@@ -762,7 +763,8 @@ pqTraceOutputMessage(PGconn *conn, const char *message, bool toServer)
                        /* No message content */
                        break;
                case PqMsg_BackendKeyData:
-                       pqTraceOutput_BackendKeyData(conn->Pfdebug, message, &logCursor, regress);
+                       pqTraceOutput_BackendKeyData(conn->Pfdebug, message, &logCursor,
+                                                                                length, regress);
                        break;
                case PqMsg_NoData:
                        fprintf(conn->Pfdebug, "NoData");
@@ -876,7 +878,8 @@ pqTraceOutputNoTypeByteMessage(PGconn *conn, const char *message)
                pqTraceOutputInt16(conn->Pfdebug, message, &logCursor);
                pqTraceOutputInt16(conn->Pfdebug, message, &logCursor);
                pqTraceOutputInt32(conn->Pfdebug, message, &logCursor, regress);
-               pqTraceOutputInt32(conn->Pfdebug, message, &logCursor, regress);
+               pqTraceOutputNchar(conn->Pfdebug, length - logCursor, message,
+                                                  &logCursor, regress);
        }
        else if (version == NEGOTIATE_SSL_CODE)
        {