libpq: Trace all messages received from the server

Not all messages that libpq received from the server would be sent
through our message tracing logic.  This commit tries to fix that by
introducing a new function pqParseDone which make it harder to forget
about doing so.

The messages that we now newly send through our tracing logic are:

- CopyData (received by COPY TO STDOUT)
- Authentication requests
- NegotiateProtocolVersion
- Some ErrorResponse messages during connection startup
- ReadyForQuery when received after a FunctionCall message

Author: Jelte Fennema-Nio <postgres@jeltef.nl>
Discussion: https://postgr.es/m/CAGECzQSoPHtZ4xe0raJ6FYSEiPPS+YWXBhOGo+Y1YecLgknF3g@mail.gmail.com

1 files changed, 15 insertions, 0 deletions

diff --git a/src/interfaces/libpq/fe-misc.c b/src/interfaces/libpq/fe-misc.c
index f235bfbb41f..928a47162d1 100644
--- a/src/interfaces/libpq/fe-misc.c
+++ b/src/interfaces/libpq/fe-misc.c
@@ -436,6 +436,21 @@ pqCheckInBufferSpace(size_t bytes_needed, PGconn *conn)
 }
 
 /*
+ * pqParseDone: after a server-to-client message has successfully
+ * been parsed, advance conn->inStart to account for it.
+ */
+void
+pqParseDone(PGconn *conn, int newInStart)
+{
+	/* trace server-to-client message */
+	if (conn->Pfdebug)
+		pqTraceOutputMessage(conn, conn->inBuffer + conn->inStart, false);
+
+	/* Mark message as done */
+	conn->inStart = newInStart;
+}
+
+/*
  * pqPutMsgStart: begin construction of a message to the server
  *
  * msg_type is the message type byte, or 0 for a message without type byte