Re: [HACKERS] listening addresses

Patch applied by Tom. Thanks.

---------------------------------------------------------------------------

Andrew Dunstan wrote:
>
>
> Andrew Dunstan wrote:
>
> >
> >
> > Tom Lane wrote:
> >
> >> Andrew Dunstan <andrew(at)dunslane(dot)net> writes:
> >>
> >>
> >>> A small problem with it was reported to me a couple of days ago -
> >>> user had firewalled off all IP6 traffic. The stats collector happily
> >>> bound and connected to the socket, but all the packets fell in the
> >>> bit bucket. They found it quite hard to diagnose the problem.
> >>>
> >>
> >>
> >>
> >>
> >>> Possible solutions that occurred to me:
> >>> . an initial "hello"-"yes i'm here" exchange to validate the address
> >>>
> >>
> >>
> >> That one seems reasonable to me. Seems like it would take just a few
> >> more lines of code in the loop that tries to find a working socket to
> >> check that we can send a byte and receive it. You'd have to be careful
> >> not to block if the socket is indeed not working ... also, is it safe to
> >> assume that a byte sent with send() is *immediately* ready to recv()?
> >>
> >>
> >>
> >
>
> Revised patch attached. I think this is about as much trouble as this
> problem is worth ;-)
>
> cheers
>
> andrew

> Index: src/backend/postmaster/pgstat.c
> ===================================================================
> RCS file: /projects/cvsroot/pgsql-server/src/backend/postmaster/pgstat.c,v
> retrieving revision 1.61
> diff -c -r1.61 pgstat.c
> *** src/backend/postmaster/pgstat.c 15 Mar 2004 16:21:37 -0000 1.61
> --- src/backend/postmaster/pgstat.c 22 Mar 2004 12:47:54 -0000
> ***************
> *** 191,196 ****
> --- 191,200 ----
> *addr,
> hints;
> int ret;
> + fd_set rset;
> + struct timeval tv;
> + char test_byte;
> + int sel_res;
>
> /*
> * Force start of collector daemon if something to collect
> ***************
> *** 307,312 ****
> --- 311,365 ----
> pgStatSock = -1;
> continue;
> }
> +
> + #define TESTBYTEVAL 99
> +
> + /* try to send and receive a test byte on the socket */
> +
> + test_byte = TESTBYTEVAL;
> + if (send(pgStatSock,&test_byte,1,0) != 1)
> + {
> + ereport(LOG,
> + (errcode_for_socket_access(),
> + errmsg("test byte send failure socket for statistics collector: %m")));
> + closesocket(pgStatSock);
> + pgStatSock = -1;
> + continue;
> + }
> + test_byte++;
> + for(;;)
> + {
> + FD_ZERO(&rset);
> + FD_SET(pgStatSock, &rset);
> + tv.tv_sec = 0;
> + tv.tv_usec = 500000;
> + sel_res = select(pgStatSock+1,&rset,NULL,NULL,&tv);
> + if (sel_res != -1 || errno != EINTR)
> + break;
> + }
> + if( sel_res > 0 && FD_ISSET(pgStatSock,&rset)
> + && recv(pgStatSock,&test_byte,1,0) == 1)
> + {
> + if(test_byte != TESTBYTEVAL)
> + {
> + ereport(LOG,
> + (errcode_for_socket_access(),
> + errmsg("incorrect test value on send/receive on socket for statistics collector")));
> + closesocket(pgStatSock);
> + pgStatSock = -1;
> + continue;
> + }
> + }
> + else
> + {
> + ereport(LOG,
> + (errcode_for_socket_access(),
> + errmsg("could receive test byte on socket for statistics collector: %m")));
> + closesocket(pgStatSock);
> + pgStatSock = -1;
> + continue;
> + }
> +
>
> /* If we get here, we have a working socket */
> break;

>
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--
Bruce Momjian | http://candle.pha.pa.us
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