On Sat, 7 Dec 2002, Vojtech Janota wrote:

> I have following problem: I've downloaded latest curl and the very simple
> program at the bottom of this mail crashes regularly on older redhats (6.0
> with glibc-2.2.4-19 and 7.3 with glibc-2.2.5-notsure). It works ok with
> RedHat 8.

Does it always crash on the same host name? If yes, is it anything special
with it?

> I guess this is a glibc problem. Is there any workaround? The program I'm
> developing MUST run on a plain RedHat 7.x systems, but I would like to make
> use of libcurl...

> #2 0x4023f6a0 in __gethostbyname_r (name=0x806e0a8 "imgt.cnusc.fr",
> resbuf=0x8080980, buffer=0x8080994 "\177", buflen=22180,
> result=0xbffff6b4, h_errnop=0xbffff6b8) at ../nss/getXXbyYY_r.c:200
> #3 0x4001d0e6 in my_getaddrinfo (data=0x8050e78,
> hostname=0x806e0a8 "imgt.cnusc.fr", port=8104, bufp=0xbffff6f4)
> at hostip.c:619

I think I know what might be causing this problem and I'd like to ask you to
try a few tweaks:

Watch the 'buflen' argument to gethostbyname_r() above. It is obscenely large
and it should in fact never grow beyond 9000 bytes (CURL_NAMELOOKUP_SIZE).

This is a bug which can be corrected by replacing a while(1) with
while(step_size <= CURL_NAMELOOKUP_SIZE) in lib/hostip.c (line 635 in the
7.10.2 version).

But, it should never reach that far since it should've given up since long
before that. I suspect that my "fix" to get Redhat 8.0 to work might've
accidentally broken earlier versions. If this is the case, I'll get a
headache. To test if this is the case, don't apply the fix I mentioned above
but instead you change the error-check on line 630 to not check for the
EAGAIN error. The EAGAIN error *SHOULD NOT* be returned for a too small
buffer size, but is what the redhat 8.0 (glibc 2.2.93) version of
gethostbyname_r() does.

It may very well be so that earlier versions sometimes return EAGAIN for some
kind of error and then we should not retry the name resolve call with a
larger buffer but we should instead bail out and return error.

Let us know what happens.

-- 
 Daniel Stenberg -- curl, cURL, Curl, CURL. Groks URLs.
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