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Reject names that are longer than 255 characters, to avoid problems with strict or buggy DNS server implementations. (Patch from the Google tree)

This commit is contained in:
Steinar H. Gunderson 2007-09-29 13:58:23 +00:00
parent d6dd848523
commit d0de9663e2
1 changed files with 17 additions and 0 deletions
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17
ares/ares_mkquery.c
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@ -108,6 +108,23 @@ int ares_mkquery(const char *name, int dnsclass, int type, unsigned short id,
if (*name && *(p - 1) != '.')
len++;
/* Immediately reject names that are longer than the maximum of 255
* bytes that's specified in RFC 1035 ("To simplify implementations,
* the total length of a domain name (i.e., label octets and label
* length octets) is restricted to 255 octets or less."). We aren't
* doing this just to be a stickler about RFCs. For names that are
* too long, 'dnscache' closes its TCP connection to us immediately
* (when using TCP) and ignores the request when using UDP, and
* BIND's named returns ServFail (TCP or UDP). Sending a request
* that we know will cause 'dnscache' to close the TCP connection is
* painful, since that makes any other outstanding requests on that
* connection fail. And sending a UDP request that we know
* 'dnscache' will ignore is bad because resources will be tied up
* until we time-out the request.
*/
if (len > MAXCDNAME)
return ARES_EBADNAME;
*buflen = len + HFIXEDSZ + QFIXEDSZ;
*buf = malloc(*buflen);
if (!*buf)