Don't log incomplete startup packet if it's empty

This will stop logging cases where, for example, a monitor opens a
connection and immediately closes it. If the packet contains any data an
incomplete packet will still be logged.

Author: Tom Lane

Discussion: https://postgr.es/m/a1379a72-2958-1ed0-ef51-09a21219b155@2ndQuadrant.com

diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index ccea231e985805cf9e7c34d3cbf36a260831437b..fe599632d3d478554a4e51b9189dac673433f4b5 100644 (file)
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -1899,17 +1899,34 @@ ProcessStartupPacket(Port *port, bool SSLdone)
    MemoryContext oldcontext;
 
    pq_startmsgread();
-   if (pq_getbytes((char *) &len, 4) == EOF)
+
+   /*
+    * Grab the first byte of the length word separately, so that we can tell
+    * whether we have no data at all or an incomplete packet.  (This might
+    * sound inefficient, but it's not really, because of buffering in
+    * pqcomm.c.)
+    */
+   if (pq_getbytes((char *) &len, 1) == EOF)
    {
        /*
-        * EOF after SSLdone probably means the client didn't like our
-        * response to NEGOTIATE_SSL_CODE.  That's not an error condition, so
-        * don't clutter the log with a complaint.
+        * If we get no data at all, don't clutter the log with a complaint;
+        * such cases often occur for legitimate reasons.  An example is that
+        * we might be here after responding to NEGOTIATE_SSL_CODE, and if the
+        * client didn't like our response, it'll probably just drop the
+        * connection.  Service-monitoring software also often just opens and
+        * closes a connection without sending anything.  (So do port
+        * scanners, which may be less benign, but it's not really our job to
+        * notice those.)
         */
-       if (!SSLdone)
-           ereport(COMMERROR,
-                   (errcode(ERRCODE_PROTOCOL_VIOLATION),
-                    errmsg("incomplete startup packet")));
+       return STATUS_ERROR;
+   }
+
+   if (pq_getbytes(((char *) &len) + 1, 3) == EOF)
+   {
+       /* Got a partial length word, so bleat about that */
+       ereport(COMMERROR,
+               (errcode(ERRCODE_PROTOCOL_VIOLATION),
+                errmsg("incomplete startup packet")));
        return STATUS_ERROR;
    }