[exim-dev] [Bug 2250] Peculiarity with SMTP delivery in Exim…

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Címzett: exim-dev
Tárgy: [exim-dev] [Bug 2250] Peculiarity with SMTP delivery in Exim 4.90.1
https://bugs.exim.org/show_bug.cgi?id=2250

--- Comment #17 from David Carter <dpc22@???> ---
(In reply to David Carter from comment #16)
> (In reply to David Carter from comment #14)
>
> > I will start bisection with DKIM disabled.
>
> 4a5cbaff2f9addfc9b4375a97ec6669bf18ee4db (Tue Sep 19 21:57:30 2017 +0100)
> has the problem. That predates 4.90.
>
> I will shut up now until I can give you a precise commit version.
>
> At one or two subdivisions a day, this might take a while...


The bug was introduced in 925ac8e4f1c5d365ddea2f7aee460cd0a3cd409d

Looking at that commit, I'm pretty certain that the culprit is:

static BOOL
wouldblock_reading(void)
{
int fd, rc;
fd_set fds;
struct timeval tzero;

if (tls_in.active >= 0 && tls_could_read())
return FALSE;

if (smtp_inptr < smtp_inend)
return FALSE;

fd = fileno(smtp_in);
FD_ZERO(&fds);
FD_SET(fd, &fds);
tzero.tv_sec = 0;
tzero.tv_usec = 0;
rc = select(fd + 1, (SELECT_ARG2_TYPE *)&fds, NULL, NULL, &tzero);

if (rc <= 0) return TRUE;     /* Not ready to read */
rc = smtp_getc(GETC_BUFFER_UNLIMITED);
if (rc < 0) return TRUE;      /* End of file or error */


smtp_ungetc(rc);
rc = smtp_inend - smtp_inptr;
if (rc > 150) rc = 150;
smtp_inptr[rc] = 0;
return FALSE;
}

I'm not sure what the last few lines of this are trying to achieve, but isn't:

rc = smtp_inend - smtp_inptr;
if (rc > 150) rc = 150;
smtp_inptr[rc] = 0;

going to introduce a single '\0' 150 characters after the current smtp_inptr?
If a long list of "RCPT TO" are pipelined, than that is likely to be real data.

Presumably this function is being called somewhere that the original
check_sync() function that it replaced was not?

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