Both approaches seem to work just fine. The add_iacs()
patch I did is smaller, and I believe fits better into
the existing structure of telnetd, such as it is:
$ size networking/telnetd.o
text data bss dec hex filename
3752 16 16 3784 ec8 networking/telnetd.o
$ # Replace add_iacs() patch with iac_safe_write() patch & rebuild...
$ size networking/telnetd.o
text data bss dec hex filename
3792 16 16 3824 ef0 networking/telnetd.o
$
(These are mips64 numbers.)
I had to apply iac_safe_write() code as a patch to what we
had, replacing my patch. (For comparison purposes.) I couldn't
get the current svn to fully build for me, and I've got nearly
zero time to spend on this. I believe the comparative results
are still valid, however.
Essentially both patches each apply one new subroutine, which
are listed here for easy comparison:
static void
add_iacs(struct tsession *ts, int *pnum_fromtty)
{
unsigned char *ptr = TS_BUF2 + ts->rdidx2;
unsigned char *end = ptr + MIN(BUFSIZE - ts->rdidx2,
*pnum_fromtty);
while (ptr < end) {
if (*ptr == IAC) {
memmove(ptr+1, ptr, end - ptr);// Results in
dupe IAC!
if (end < TS_BUF2 + BUFSIZE)
end++;
(*pnum_fromtty)++;
ptr++; // Don't process the dupe next time
either.
}
ptr++;
}
}
*** Versus ***
static size_t iac_safe_write(int fd, const char *buf, size_t count)
{
const char *oxff;
size_t wr, rc, total;
total = 0;
while (1) {
if (count == 0)
return total;
if (*buf == (char)0xff) {
rc = safe_write(fd, "\xff\xff", 2);
if (rc != 2)
break;
buf++;
total++;
count--;
continue;
}
/* count != 0, *buf != 0xff */
oxff = memchr(buf, 0xff, count);
wr = count;
if (oxff)
wr = oxff - buf;
rc = safe_write(fd, buf, wr);
if (rc != wr)
break;
buf += rc;
total += rc;
count -= rc;
}
/* here: rc - result of last short write */
if ((ssize_t)rc < 0) { /* error? */
if (total == 0)
return rc;
rc = 0;
}
return total + rc;
}
I happen to think that mine is simpler; it's for certain smaller!
-- Jim
-----Original Message-----
From: Denys Vlasenko [mailto:[EMAIL PROTECTED]
Sent: Tuesday, November 11, 2008 4:28 PM
To: Cathey, Jim
Cc: [email protected]
Subject: Re: outstanding telnetd bug fix, and two new features
On Wednesday 12 November 2008 01:00, Cathey, Jim wrote:
> OK, I have tried out a new version of telnetd.c that
> contains all the patches we've used before (including
> the one you don't like), and also adds an add_iacs()
> function to take care of escaping literal 0xFF characters
> going the other way. Herewith is the diff -u patch.
> Seemed to work for me, and even preserves the existing
> bug structure of the semi-circular buffers in telnetd.
Wow... I fixed it in svn just last night (around 04:00 am).
orry for not informing you. Can you try version from svn?
--
vda
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