site_archiver@lists.apple.com Delivered-To: darwin-dev@lists.apple.com Thread-index: AcoayRXDv8kXFlABT/a/fuDuHqsvUw== Thread-topic: Re: dns_lookup returns NULL? I'll buy that. Any idea why on 10.6 it would suddenly start returning NULL for all lookups and continue to do so until a reboot? Tried restarting DS as well to no avail but a reboot seems to solve the problem once the system gets in that state. Where should I start looking for debug info? Note that dig and nslookup work fine, but I suspect they don't use this API. mp Date: Mon, 10 Aug 2009 15:25:55 -0700 From: Marc Majka <majka@apple.com> Subject: Re: dns_lookup returns NULL? To: appledev <appledev@centrify.com> Cc: darwin-dev@lists.apple.com Message-ID: <EB755AEA-2B4B-4D95-B453-4E538C1E6EC2@apple.com> Content-Type: text/plain; charset="us-ascii" The "status" field of the dns_reply_t structure is currently unused (it's always zero). There's really not a lot of useful error information that could be returned by this level of API. dns_lookup() may do multiple queries to multiple DNS clients (see the resolver(5) man page). If none of the resolvers returned useful data for the query, dns_lookup() returns NULL. A failure like NXDomain from a particular nameserver really doesn't mean much if dns_lookup() is searching multiple sources. The situation is similar to an API like, say, getpwnam(). The DirectoryService daemon might search many different information sources to answer a getpwnam() query. If it finds data, it returns it. It really doesn't mean a lot if, as part of it's search, it got an error from an LDAP or NIS server, or if it checked /etc/passwd and failed to find a particular user. A reply is really a composite of all of the sub-searchs performed to answer a query. A NULL reply means they all "failed" in some way, but the API abstracts away the return codes for the various sub-systems. -- Marc Majka On 10 Aug, 2009, at 14:37, Mike Patnode wrote:

Is there anyway to get error information when dns_lookup() returns NULL? It looks like the error code is supposed to be returned in the dns_reply_t structure. What does it mean when the return value is NULL?

thx mp _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-dev mailing list (Darwin-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-dev/majka%40apple.com

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