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

src/interfaces/libpq/fe-auth.c

@@ -94,6 +94,10 @@ pg_GSS_continue(PGconn *conn, int payloadlen)
 		ginbuf.value = NULL;
 	}
 
+	/* finished parsing, trace server-to-client message */
+	if (conn->Pfdebug)
+		pqTraceOutputMessage(conn, conn->inBuffer + conn->inStart, false);
+
 	/* Only try to acquire credentials if GSS delegation isn't disabled. */
 	if (!pg_GSS_have_cred_cache(&conn->gcred))
 		conn->gcred = GSS_C_NO_CREDENTIAL;
@@ -258,6 +262,10 @@ pg_SSPI_continue(PGconn *conn, int payloadlen)
 		InBuffers[0].BufferType = SECBUFFER_TOKEN;
 	}
 
+	/* finished parsing, trace server-to-client message */
+	if (conn->Pfdebug)
+		pqTraceOutputMessage(conn, conn->inBuffer + conn->inStart, false);
+
 	OutBuffers[0].pvBuffer = NULL;
 	OutBuffers[0].BufferType = SECBUFFER_TOKEN;
 	OutBuffers[0].cbBuffer = 0;
@@ -563,6 +571,10 @@ pg_SASL_init(PGconn *conn, int payloadlen)
 		}
 	}
 
+	/* finished parsing, trace server-to-client message */
+	if (conn->Pfdebug)
+		pqTraceOutputMessage(conn, conn->inBuffer + conn->inStart, false);
+
 	Assert(conn->sasl);
 
 	/*
@@ -651,6 +663,11 @@ pg_SASL_continue(PGconn *conn, int payloadlen, bool final)
 		free(challenge);
 		return STATUS_ERROR;
 	}
+
+	/* finished parsing, trace server-to-client message */
+	if (conn->Pfdebug)
+		pqTraceOutputMessage(conn, conn->inBuffer + conn->inStart, false);
+
 	/* For safety and convenience, ensure the buffer is NULL-terminated. */
 	challenge[payloadlen] = '\0';
 
@@ -716,6 +733,10 @@ pg_password_sendauth(PGconn *conn, const char *password, AuthRequest areq)
 			return STATUS_ERROR;	/* shouldn't happen */
 	}
 
+	/* finished parsing, trace server-to-client message */
+	if (conn->Pfdebug)
+		pqTraceOutputMessage(conn, conn->inBuffer + conn->inStart, false);
+
 	/* Encrypt the password if needed. */
 
 	switch (areq)

src/interfaces/libpq/fe-connect.c

@@ -3797,7 +3797,7 @@ keep_going:						/* We will come back to here until there is
 						return PGRES_POLLING_READING;
 					}
 					/* OK, we read the message; mark data consumed */
-					conn->inStart = conn->inCursor;
+					pqParseDone(conn, conn->inCursor);
 
 					/*
 					 * Before 7.2, the postmaster didn't always end its
@@ -3847,7 +3847,7 @@ keep_going:						/* We will come back to here until there is
 						goto error_return;
 					}
 					/* OK, we read the message; mark data consumed */
-					conn->inStart = conn->inCursor;
+					pqParseDone(conn, conn->inCursor);
 
 					/*
 					 * If error is "cannot connect now", try the next host if
@@ -3876,7 +3876,7 @@ keep_going:						/* We will come back to here until there is
 						goto error_return;
 					}
 					/* OK, we read the message; mark data consumed */
-					conn->inStart = conn->inCursor;
+					pqParseDone(conn, conn->inCursor);
 					goto error_return;
 				}
 
@@ -3901,7 +3901,11 @@ keep_going:						/* We will come back to here until there is
 				 */
 				res = pg_fe_sendauth(areq, msgLength, conn);
 
-				/* OK, we have processed the message; mark data consumed */
+				/*
+				 * OK, we have processed the message; mark data consumed.  We
+				 * don't call pqParseDone here because we already traced this
+				 * message inside pg_fe_sendauth.
+				 */
 				conn->inStart = conn->inCursor;
 
 				if (res != STATUS_OK)

src/interfaces/libpq/fe-misc.c

@@ -435,6 +435,21 @@ pqCheckInBufferSpace(size_t bytes_needed, PGconn *conn)
 	return EOF;
 }
 
+/*
+ * 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
  *

src/interfaces/libpq/fe-protocol3.c

@@ -454,12 +454,8 @@ pqParseInput3(PGconn *conn)
 		/* Successfully consumed this message */
 		if (conn->inCursor == conn->inStart + 5 + msgLength)
 		{
-			/* trace server-to-client message */
-			if (conn->Pfdebug)
-				pqTraceOutputMessage(conn, conn->inBuffer + conn->inStart, false);
-
 			/* Normal case: parsing agrees with specified length */
-			conn->inStart = conn->inCursor;
+			pqParseDone(conn, conn->inCursor);
 		}
 		else
 		{
@@ -1728,12 +1724,8 @@ getCopyDataMessage(PGconn *conn)
 				return -1;
 		}
 
-		/* trace server-to-client message */
-		if (conn->Pfdebug)
-			pqTraceOutputMessage(conn, conn->inBuffer + conn->inStart, false);
-
 		/* Drop the processed message and loop around for another */
-		conn->inStart = conn->inCursor;
+		pqParseDone(conn, conn->inCursor);
 	}
 }
 
@@ -1791,13 +1783,13 @@ pqGetCopyData3(PGconn *conn, char **buffer, int async)
 			(*buffer)[msgLength] = '\0';	/* Add terminating null */
 
 			/* Mark message consumed */
-			conn->inStart = conn->inCursor + msgLength;
+			pqParseDone(conn, conn->inCursor + msgLength);
 
 			return msgLength;
 		}
 
 		/* Empty, so drop it and loop around for another */
-		conn->inStart = conn->inCursor;
+		pqParseDone(conn, conn->inCursor);
 	}
 }
 
@@ -2168,8 +2160,9 @@ pqFunctionCall3(PGconn *conn, Oid fnid,
 			case 'Z':			/* backend is ready for new query */
 				if (getReadyForQuery(conn))
 					continue;
-				/* consume the message and exit */
-				conn->inStart += 5 + msgLength;
+
+				/* consume the message */
+				pqParseDone(conn, conn->inStart + 5 + msgLength);
 
 				/*
 				 * If we already have a result object (probably an error), use
@@ -2194,6 +2187,7 @@ pqFunctionCall3(PGconn *conn, Oid fnid,
 						pqSaveErrorResult(conn);
 					}
 				}
+				/* and we're out */
 				return pqPrepareAsyncResult(conn);
 			case 'S':			/* parameter status */
 				if (getParameterStatus(conn))
@@ -2203,18 +2197,18 @@ pqFunctionCall3(PGconn *conn, Oid fnid,
 				/* The backend violates the protocol. */
 				libpq_append_conn_error(conn, "protocol error: id=0x%x", id);
 				pqSaveErrorResult(conn);
-				/* trust the specified message length as what to skip */
+
+				/*
+				 * We can't call parsing done due to the protocol violation
+				 * (so message tracing wouldn't work), but trust the specified
+				 * message length as what to skip.
+				 */
 				conn->inStart += 5 + msgLength;
 				return pqPrepareAsyncResult(conn);
 		}
 
-		/* trace server-to-client message */
-		if (conn->Pfdebug)
-			pqTraceOutputMessage(conn, conn->inBuffer + conn->inStart, false);
-
-		/* Completed this message, keep going */
-		/* trust the specified message length as what to skip */
-		conn->inStart += 5 + msgLength;
+		/* Completed parsing this message, keep going */
+		pqParseDone(conn, conn->inStart + 5 + msgLength);
 		needInput = false;
 	}
 

src/interfaces/libpq/fe-trace.c

@@ -280,6 +280,14 @@ pqTraceOutput_CommandComplete(FILE *f, const char *message, int *cursor)
 	pqTraceOutputString(f, message, cursor, false);
 }
 
+static void
+pqTraceOutput_CopyData(FILE *f, const char *message, int *cursor, int length,
+					   bool suppress)
+{
+	fprintf(f, "CopyData\t");
+	pqTraceOutputNchar(f, length - *cursor + 1, message, cursor, suppress);
+}
+
 static void
 pqTraceOutput_DataRow(FILE *f, const char *message, int *cursor)
 {
@@ -472,10 +480,58 @@ pqTraceOutput_Query(FILE *f, const char *message, int *cursor)
 }
 
 static void
-pqTraceOutput_Authentication(FILE *f, const char *message, int *cursor)
+pqTraceOutput_Authentication(FILE *f, const char *message, int *cursor,
+							 int length, bool suppress)
 {
-	fprintf(f, "Authentication\t");
-	pqTraceOutputInt32(f, message, cursor, false);
+	int			authType = 0;
+
+	memcpy(&authType, message + *cursor, 4);
+	authType = (int) pg_ntoh32(authType);
+	*cursor += 4;
+	switch (authType)
+	{
+		case AUTH_REQ_OK:
+			fprintf(f, "AuthenticationOk");
+			break;
+			/* AUTH_REQ_KRB4 not supported */
+			/* AUTH_REQ_KRB5 not supported */
+		case AUTH_REQ_PASSWORD:
+			fprintf(f, "AuthenticationCleartextPassword");
+			break;
+			/* AUTH_REQ_CRYPT not supported */
+		case AUTH_REQ_MD5:
+			fprintf(f, "AuthenticationMD5Password");
+			break;
+		case AUTH_REQ_GSS:
+			fprintf(f, "AuthenticationGSS");
+			break;
+		case AUTH_REQ_GSS_CONT:
+			fprintf(f, "AuthenticationGSSContinue\t");
+			pqTraceOutputNchar(f, length - *cursor + 1, message, cursor,
+							   suppress);
+			break;
+		case AUTH_REQ_SSPI:
+			fprintf(f, "AuthenticationSSPI");
+			break;
+		case AUTH_REQ_SASL:
+			fprintf(f, "AuthenticationSASL\t");
+			while (message[*cursor] != '\0')
+				pqTraceOutputString(f, message, cursor, false);
+			pqTraceOutputString(f, message, cursor, false);
+			break;
+		case AUTH_REQ_SASL_CONT:
+			fprintf(f, "AuthenticationSASLContinue\t");
+			pqTraceOutputNchar(f, length - *cursor + 1, message, cursor,
+							   suppress);
+			break;
+		case AUTH_REQ_SASL_FIN:
+			fprintf(f, "AuthenticationSASLFinal\t");
+			pqTraceOutputNchar(f, length - *cursor + 1, message, cursor,
+							   suppress);
+			break;
+		default:
+			fprintf(f, "Unknown authentication message %d", authType);
+	}
 }
 
 static void
@@ -625,7 +681,8 @@ pqTraceOutputMessage(PGconn *conn, const char *message, bool toServer)
 				pqTraceOutput_CommandComplete(conn->Pfdebug, message, &logCursor);
 			break;
 		case PqMsg_CopyData:
-			/* Drop COPY data to reduce the overhead of logging. */
+			pqTraceOutput_CopyData(conn->Pfdebug, message, &logCursor,
+								   length, regress);
 			break;
 		case PqMsg_Describe:
 			/* Describe(F) and DataRow(B) use the same identifier. */
@@ -714,7 +771,8 @@ pqTraceOutputMessage(PGconn *conn, const char *message, bool toServer)
 			pqTraceOutput_Query(conn->Pfdebug, message, &logCursor);
 			break;
 		case PqMsg_AuthenticationRequest:
-			pqTraceOutput_Authentication(conn->Pfdebug, message, &logCursor);
+			pqTraceOutput_Authentication(conn->Pfdebug, message, &logCursor,
+										 length, regress);
 			break;
 		case PqMsg_PortalSuspended:
 			fprintf(conn->Pfdebug, "PortalSuspended");

src/interfaces/libpq/libpq-int.h

@@ -753,6 +753,7 @@ extern PGresult *pqFunctionCall3(PGconn *conn, Oid fnid,
   */
 extern int	pqCheckOutBufferSpace(size_t bytes_needed, PGconn *conn);
 extern int	pqCheckInBufferSpace(size_t bytes_needed, PGconn *conn);
+extern void pqParseDone(PGconn *conn, int newInStart);
 extern int	pqGetc(char *result, PGconn *conn);
 extern int	pqPutc(char c, PGconn *conn);
 extern int	pqGets(PQExpBuffer buf, PGconn *conn);