25 Commits (2c8859c2e725af2de59203c0b2d39b96f135cb60)

Author	SHA1	Message	Date
Andrew Dunham	7fe6e50858	net/dns/resolver: fix test flake ... Updates #13902 Signed-off-by: Andrew Dunham <andrew@du.nham.ca> Change-Id: Ib2def19caad17367e9a31786ac969278e65f51c6	1 month ago
Nick Khyl	f07ff47922	net/dns/resolver: add tests for using a forwarder with multiple upstream resolvers ... If multiple upstream DNS servers are available, quad-100 sends requests to all of them and forwards the first successful response, if any. If no successful responses are received, it propagates the first failure from any of them. This PR adds some test coverage for these scenarios. Updates #13571 Signed-off-by: Nick Khyl <nickk@tailscale.com>	2 months ago
Nick Hill	c2144c44a3	net/dns/resolver: update (*forwarder).forwardWithDestChan to always return an error unless it sends a response to responseChan ... We currently have two executions paths where (*forwarder).forwardWithDestChan returns nil, rather than an error, without sending a DNS response to responseChan. These paths are accompanied by a comment that reads: // Returning an error will cause an internal retry, there is // nothing we can do if parsing failed. Just drop the packet. But it is not (or no longer longer) accurate: returning an error from forwardWithDestChan does not currently cause a retry. Moreover, although these paths are currently unreachable due to implementation details, if (*forwarder).forwardWithDestChan were to return nil without sending a response to responseChan, it would cause a deadlock at one call site and a panic at another. Therefore, we update (*forwarder).forwardWithDestChan to return errors in those two paths and remove comments that were no longer accurate and misleading. Updates #cleanup Updates #13571 Signed-off-by: Nick Hill <mykola.khyl@gmail.com>	2 months ago
James Tucker	af5a845a87	net/dns/resolver: fix dns-sd NXDOMAIN responses from quad-100 ... mdnsResponder at least as of macOS Sequoia does not find NXDOMAIN responses to these dns-sd PTR queries acceptable unless they include the question section in the response. This was found debugging #13511, once we turned on additional diagnostic reporting from mdnsResponder we witnessed: ``` Received unacceptable 12-byte response from 100.100.100.100 over UDP via utun6/27 -- id: 0x7F41 (32577), flags: 0x8183 (R/Query, RD, RA, NXDomain), counts: 0/0/0/0, ``` If the response includes a question section, the resposnes are acceptable, e.g.: ``` Received acceptable 59-byte response from 8.8.8.8 over UDP via en0/17 -- id: 0x2E55 (11861), flags: 0x8183 (R/Query, RD, RA, NXDomain), counts: 1/0/0/0, ``` This may be contributing to an issue under diagnosis in #13511 wherein some combination of conditions results in mdnsResponder no longer answering DNS queries correctly to applications on the system for extended periods of time (multiple minutes), while dig against quad-100 provides correct responses for those same domains. If additional debug logging is enabled in mdnsResponder we see it reporting: ``` Penalizing server 100.100.100.100 for 60 seconds ``` It is also possible that the reason that macOS & iOS never "stopped spamming" these queries is that they have never been replied to with acceptable responses. It is not clear if this special case handling of dns-sd PTR queries was ever beneficial, and given this evidence may have always been harmful. If we subsequently observe that the queries settle down now that they have acceptable responses, we should remove these special cases - making upstream queries very occasionally isn't a lot of battery, so we should be better off having to maintain less special cases and avoid bugs of this class. Updates #2442 Updates #3025 Updates #3363 Updates #3594 Updates #13511 Signed-off-by: James Tucker <james@tailscale.com>	2 months ago
Nick Khyl	f23932bd98	net/dns/resolver: log forwarded query details when TS_DEBUG_DNS_FORWARD_SEND is enabled ... Troubleshooting DNS resolution issues often requires additional information. This PR expands the effect of the TS_DEBUG_DNS_FORWARD_SEND envknob to forwarder.forwardWithDestChan, and includes the request type, domain name length, and the first 3 bytes of the domain's SHA-256 hash in the output. Fixes #13070 Signed-off-by: Nick Khyl <nickk@tailscale.com>	4 months ago
Jonathan Nobels	19b0c8a024	net/dns, health: raise health warning for failing forwarded DNS queries (#12888) ... updates tailscale/corp#21823 Misconfigured, broken, or blocked DNS will often present as "internet is broken'" to the end user. This plumbs the health tracker into the dns manager and forwarder and adds a health warning with a 5 second delay that is raised on failures in the forwarder and lowered on successes. Signed-off-by: Jonathan Nobels <jonathan@tailscale.com>	4 months ago
Brad Fitzpatrick	7c1d6e35a5	all: use Go 1.22 range-over-int ... Updates #11058 Change-Id: I35e7ef9b90e83cac04ca93fd964ad00ed5b48430 Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>	7 months ago
alexelisenko	fe22032fb3	net/dns/{publicdns,resolver}: add start of Control D support ... Updates #7946 [@bradfitz fixed up version of #8417] Change-Id: I1dbf6fa8d525b25c0d7ad5c559a7f937c3cd142a Signed-off-by: alexelisenko <39712468+alexelisenko@users.noreply.github.com> Signed-off-by: Alex Paguis <alex@windscribe.com>	8 months ago
Andrew Dunham	91b9899402	net/dns/resolver: fix flaky test ... Updates #cleanup Signed-off-by: Andrew Dunham <andrew@du.nham.ca> Change-Id: I2d073220bb6ac78ba88d8be35085cc23b727d69f	1 year ago
Andrew Dunham	286c6ce27c	net/dns/resolver: race UDP and TCP queries (#9544) ... Instead of just falling back to making a TCP query to an upstream DNS server when the UDP query returns a truncated query, also start a TCP query in parallel with the UDP query after a given race timeout. This ensures that if the upstream DNS server does not reply over UDP (or if the response packet is blocked, or there's an error), we can still make queries if the server replies to TCP queries. This also adds a new package, util/race, to contain the logic required for racing two different functions and returning the first non-error answer. Updates tailscale/corp#14809 Signed-off-by: Andrew Dunham <andrew@du.nham.ca> Change-Id: I4311702016c1093b1beaa31b135da1def6d86316	1 year ago
Andrew Dunham	530aaa52f1	net/dns: retry forwarder requests over TCP ... We weren't correctly retrying truncated requests to an upstream DNS server with TCP. Instead, we'd return a truncated request to the user, even if the user was querying us over TCP and thus able to handle a large response. Also, add an envknob and controlknob to allow users/us to disable this behaviour if it turns out to be buggy (✨ DNS ✨). Updates #9264 Signed-off-by: Andrew Dunham <andrew@du.nham.ca> Change-Id: Ifb04b563839a9614c0ba03e9c564e8924c1a2bfd	1 year ago
Mihai Parparita	0e3fb91a39	net/dns/resolver: remove maxDoHInFlight ... It was originally added to control memory use on iOS (#2490), but then was relaxed conditionally when running on iOS 15 (#3098). Now that we require iOS 15, there's no need for the limit at all, so simplify back to the original state. Signed-off-by: Mihai Parparita <mihai@tailscale.com>	2 years ago
Will Norris	71029cea2d	all: update copyright and license headers ... This updates all source files to use a new standard header for copyright and license declaration. Notably, copyright no longer includes a date, and we now use the standard SPDX-License-Identifier header. This commit was done almost entirely mechanically with perl, and then some minimal manual fixes. Updates #6865 Signed-off-by: Will Norris <will@tailscale.com>	2 years ago
Brad Fitzpatrick	2aade349fc	net/dns, types/dnstypes: update some comments, tests for DoH ... Clarify & verify that some DoH URLs can be sent over tailcfg in some limited cases. Updates #2452 Change-Id: Ibb25db77788629c315dc26285a1059a763989e24 Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>	2 years ago
Brad Fitzpatrick	58abae1f83	net/dns/{publicdns,resolver}: add NextDNS DoH support ... NextDNS is unique in that users create accounts and then get user-specific DNS IPs & DoH URLs. For DoH, the customer ID is in the URL path. For IPv6, the IP address includes the customer ID in the lower bits. For IPv4, there's a fragile "IP linking" mechanism to associate your public IPv4 with an assigned NextDNS IPv4 and that tuple maps to your customer ID. We don't use the IP linking mechanism. Instead, NextDNS is DoH-only. Which means using NextDNS necessarily shunts all DNS traffic through 100.100.100.100 (programming the OS to use 100.100.100.100 as the global resolver) because operating systems can't usually do DoH themselves. Once it's in Tailscale's DoH client, we then connect out to the known NextDNS IPv4/IPv6 anycast addresses. If the control plane sends the client a NextDNS IPv6 address, we then map it to the corresponding NextDNS DoH with the same client ID, and we dial that DoH server using the combination of v4/v6 anycast IPs. Updates #2452 Change-Id: I3439d798d21d5fc9df5a2701839910f5bef85463 Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>	2 years ago
Andrew Dunham	c7993d2b88	net/dns/resolver: add fuzz/unit test for #2533 (#5018) ... Signed-off-by: Andrew Dunham <andrew@du.nham.ca>	2 years ago
Maisem Ali	fd99c54e10	tailcfg,all: change structs to []*dnstype.Resolver ... Signed-off-by: Maisem Ali <maisem@tailscale.com>	3 years ago
Brad Fitzpatrick	cc575fe4d6	net/dns: schedule DoH upgrade explicitly, fix Resolver.Addr confusion ... Two changes in one: * make DoH upgrades an explicitly scheduled send earlier, when we come up with the resolvers-and-delay send plan. Previously we were getting e.g. four Google DNS IPs and then spreading them out in time (for back when we only did UDP) but then later we added DoH upgrading at the UDP packet layer, which resulted in sometimes multiple DoH queries to the same provider running (each doing happy eyeballs dialing to 4x IPs themselves) for each of the 4 source IPs. Instead, take those 4 Google/Cloudflare IPs and schedule 5 things: first the DoH query (which can use all 4 IPs), and then each of the 4 IPs as UDP later. * clean up the dnstype.Resolver.Addr confusion; half the code was using it as an IP string (as documented) as half was using it as an IP:port (from some prior type we used), primarily for tests. Instead, document it was being primarily an IP string but also accepting an IP:port for tests, then add an accessor method on it to get the IPPort and use that consistently everywhere. Change-Id: Ifdd72b9e45433a5b9c029194d50db2b9f9217b53 Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>	3 years ago
Brad Fitzpatrick	ecea6cb994	net/dns/resolver: make DoH dialer use existing dnscache happy eyeball dialer ... Simplify the ability to reason about the DoH dialing code by reusing the dnscache's dialer we already have. Also, reduce the scope of the "ip" variable we don't want to close over. This necessarily adds a new field to dnscache.Resolver: SingleHostStaticResult, for when the caller already knows the IPs to be returned. Change-Id: I9f2aef7926f649137a5a3e63eebad6a3fffa48c0 Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>	3 years ago
Brad Fitzpatrick	f2041c9088	all: use strings.Cut even more ... Change-Id: I943ce72c6f339589235bddbe10d07799c4e37979 Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>	3 years ago
Brad Fitzpatrick	394c9de02b	net/dns/resolver: add nameFromQuery benchmark ... To convince me it's not as alloc-y as it looks. Change-Id: I503a0cc267268a23d2973dfde9833c420be4e868 Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>	3 years ago
Maisem Ali	7817ab6b20	net/dns/resolver: set maxDoHInFlight to 1000 on iOS 15+. ... Signed-off-by: Maisem Ali <maisem@tailscale.com>	3 years ago
Smitty	b382161fe5	tsdns: don't forward transient DNS errors ... When a DNS server claims to be unable or unwilling to handle a request, instead of passing that refusal along to the client, just treat it as any other error trying to connect to the DNS server. This prevents DNS requests from failing based on if a server can respond with a transient error before another server is able to give an actual response. DNS requests only failing *sometimes* is really hard to find the cause of (#1033). Signed-off-by: Smitty <me@smitop.com>	3 years ago
David Crawshaw	9502b515f1	net/dns: replace resolver IPs with type for DoH ... We currently plumb full URLs for DNS resolvers from the control server down to the client. But when we pass the values into the net/dns package, we throw away any URL that isn't a bare IP. This commit continues the plumbing, and gets the URL all the way to the built in forwarder. (It stops before plumbing URLs into the OS configurations that can handle them.) For #2596 Signed-off-by: David Crawshaw <crawshaw@tailscale.com>	3 years ago
Brad Fitzpatrick	54e33b511a	net/dns/resolver: add test that I forgot to git add earlier ... This was meant to be part of 53a2f63658 earlier but I guess I failed at git. Updates #2436 Updates tailscale/corp#2250 Updates tailscale/corp#2238 Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>	3 years ago