From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.org/gmane.linux.lib.musl.general/6720 Path: news.gmane.org!not-for-mail From: Rich Felker Newsgroups: gmane.linux.lib.musl.general Subject: Re: Merging ns_parse from Alpine Date: Sun, 14 Dec 2014 12:23:42 -0500 Message-ID: <20141214172342.GG4574@brightrain.aerifal.cx> References: <20141214004320.GA17102@brightrain.aerifal.cx> <20141214073650.GA1330@euler> Reply-To: musl@lists.openwall.com NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Trace: ger.gmane.org 1418577844 3573 80.91.229.3 (14 Dec 2014 17:24:04 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sun, 14 Dec 2014 17:24:04 +0000 (UTC) To: musl@lists.openwall.com Original-X-From: musl-return-6733-gllmg-musl=m.gmane.org@lists.openwall.com Sun Dec 14 18:23:59 2014 Return-path: Envelope-to: gllmg-musl@m.gmane.org Original-Received: from mother.openwall.net ([195.42.179.200]) by plane.gmane.org with smtp (Exim 4.69) (envelope-from ) id 1Y0Ctj-0006se-4B for gllmg-musl@m.gmane.org; Sun, 14 Dec 2014 18:23:59 +0100 Original-Received: (qmail 28485 invoked by uid 550); 14 Dec 2014 17:23:57 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: Original-Received: (qmail 28475 invoked from network); 14 Dec 2014 17:23:56 -0000 Content-Disposition: inline In-Reply-To: <20141214073650.GA1330@euler> User-Agent: Mutt/1.5.21 (2010-09-15) Original-Sender: Rich Felker Xref: news.gmane.org gmane.linux.lib.musl.general:6720 Archived-At: On Sun, Dec 14, 2014 at 08:38:15AM +0100, Felix Janda wrote: > Rich Felker wrote: > > I'm working on merging Timo's patch for ns_parse: > > > > http://git.alpinelinux.org/cgit/aports/tree/main/musl/1001-add-basic-dns-record-parsing-functions.patch?id=81d50064c335467fdfd80368bac6707d70db1af7 > > > > The first issue that came up in the process is that arpa/nameser.h, > > which was previously not used by musl itself and really should never > > have been accepted in its current form, is full of junk like > > statement-expressions. Including it in a file that will be compiled > > with musl adds build dependency on these nonstandard features. I > > cleaned that up with no problem (just un-inlining the macros since > > we're adding function versions anyway), but there are a few more > > issues. > > The NS_GET* macros still seem to be used a lot in the code. Yes because they also advance the pointer, and this behavior was intentional in the code. I don't think it hurts to use them once they're fixed to be function calls. > I didn't notice any missed checks but I think that some checks can be > simplified: > > [..] > > int ns_initparse(const unsigned char *msg, int msglen, ns_msg *handle) > > { > > int i, r; > > > > handle->_msg = msg; > > handle->_eom = msg + msglen; > > if (msglen < (2 + ns_s_max) * NS_INT16SZ) goto bad; > > > NS_GET16(handle->_id, msg); > > NS_GET16(handle->_flags, msg); > > for (i = 0; i < ns_s_max; i++) { > > if (NS_INT16SZ > handle->_eom - msg) goto bad; > > Isn't this uneccessary given the above check? I think you're right. I missed that. > [...] > > int ns_skiprr(const unsigned char *ptr, const unsigned char *eom, ns_sect section, int count) > > { > > const unsigned char *p = ptr; > > int r; > > > > while (count--) { > > r = dn_skipname(p, eom); > > if (r < 0) goto bad; > > if (r + 2 * NS_INT16SZ > eom - p) goto bad; > > p += r + 2 * NS_INT16SZ; > > if (section != ns_s_qd) { > > if (NS_INT32SZ + NS_INT16SZ > eom - p) goto bad; > > p += NS_INT32SZ; > > NS_GET16(r, p); > > if (r > eom - p) goto bad; > > Couldn't the two checks be combined into one? No, r is not read until after the first check, using the result of the first check. The read is hidden in the hideous macro that stores a result rather than returning it... > > int ns_parserr(ns_msg *handle, ns_sect section, int rrnum, ns_rr *rr) > > { > > int r; > > > > if (section < 0 || section >= ns_s_max) goto bad; > > if (section != handle->_sect) { > > handle->_sect = section; > > handle->_rrnum = 0; > > handle->_msg_ptr = handle->_sections[section]; > > } > > if (rrnum == -1) rrnum = handle->_rrnum; > > if (rrnum < 0 || rrnum >= handle->_counts[section]) goto bad; > > if (rrnum < handle->_rrnum) { > > handle->_rrnum = 0; > > handle->_msg_ptr = handle->_sections[section]; > > } > > if (rrnum > handle->_rrnum) { > > r = ns_skiprr(handle->_msg_ptr, handle->_eom, section, rrnum - handle->_rrnum); > > if (r < 0) return -1; > > handle->_msg_ptr += r; > > handle->_rrnum = rrnum; > > } > > r = dn_expand(handle->_msg, handle->_eom, handle->_msg_ptr, rr->name, NS_MAXDNAME); > > if (r < 0) return -1; > > dn_expand doesn't set errno. Maybe we should just call ns_name_uncompress (below) instead here? > [...] > > int ns_name_uncompress(const unsigned char *msg, const unsigned char *eom, > > const unsigned char *src, char *dst, size_t dstsiz) > > { > > int r; > > r = dn_expand(msg, eom, src, dst, dstsiz); > > if (r < 0) errno = EMSGSIZE; > > return r; > > } Does that sound better? Rich