From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-Status: No, score=-4.1 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED, SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from neon.ruby-lang.org (neon.ruby-lang.org [221.186.184.75]) by dcvr.yhbt.net (Postfix) with ESMTP id B37D61F66E for ; Tue, 11 Aug 2020 08:34:30 +0000 (UTC) Received: from neon.ruby-lang.org (localhost [IPv6:::1]) by neon.ruby-lang.org (Postfix) with ESMTP id 20F6E120905; Tue, 11 Aug 2020 17:33:57 +0900 (JST) Received: from xtrwkhkc.outbound-mail.sendgrid.net (xtrwkhkc.outbound-mail.sendgrid.net [167.89.16.28]) by neon.ruby-lang.org (Postfix) with ESMTPS id 82A0212091A for ; Tue, 11 Aug 2020 17:33:54 +0900 (JST) Received: by filterdrecv-p3mdw1-7ff865655c-r6gqk with SMTP id filterdrecv-p3mdw1-7ff865655c-r6gqk-19-5F32580E-38 2020-08-11 08:34:22.520422835 +0000 UTC m=+1088289.007383812 Received: from herokuapp.com (unknown) by ismtpd0053p1mdw1.sendgrid.net (SG) with ESMTP id 5cEkbnAHRfiuU_uiuZzMsQ for ; Tue, 11 Aug 2020 08:34:22.405 +0000 (UTC) Date: Tue, 11 Aug 2020 08:34:22 +0000 (UTC) From: daniel@rikowski.info Message-ID: References: Mime-Version: 1.0 X-Redmine-MailingListIntegration-Message-Ids: 75377 X-Redmine-Project: ruby-master X-Redmine-Issue-Tracker: Bug X-Redmine-Issue-Id: 17112 X-Redmine-Issue-Author: daniel-rikowski X-Redmine-Sender: daniel-rikowski X-Mailer: Redmine X-Redmine-Host: bugs.ruby-lang.org X-Redmine-Site: Ruby Issue Tracking System X-Auto-Response-Suppress: All Auto-Submitted: auto-generated X-SG-EID: =?us-ascii?Q?8sy4RigFvRTdBfCVJrT9zZ=2FAROhmGDIqA4SKUkX2aGzG7DOJCuREMPo2FUzVXA?= =?us-ascii?Q?Vsl37WUbMYE9KleeeJN+HAH18fgpsG3qZMXf9eU?= =?us-ascii?Q?phyzQNDQX2WTWJdQRxoCS0pf5p+lQH6gXmLRUzA?= =?us-ascii?Q?XWqYfd3noe1iiOhsxjdSBE9sgtDF5eCO0xUf34q?= =?us-ascii?Q?eUbmCWlRqhyrut3fUDnDQs4pVs5CbD5KaY9n3t+?= =?us-ascii?Q?lbysuZTk46zSmcMj4=3D?= To: ruby-core@ruby-lang.org X-ML-Name: ruby-core X-Mail-Count: 99552 Subject: [ruby-core:99552] [Ruby master Bug#17112] Resolv.getaddress fails with IPv6 link-local addresses X-BeenThere: ruby-core@ruby-lang.org X-Mailman-Version: 2.1.15 Precedence: list Reply-To: Ruby developers List-Id: Ruby developers List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: ruby-core-bounces@ruby-lang.org Sender: "ruby-core" Issue #17112 has been updated by daniel-rikowski (Daniel Rikowski). After some experiments I noticed that changing `use_ipv6?` isn't sufficient. In `Resolv#each_address` there seems to be a check for IP addresses. In case an IP address is given no actual resolving is performed. ```ruby if AddressRegex =~ name yield name return end ``` with ```ruby AddressRegex = /(?:#{IPv4::Regex})|(?:#{IPv6::Regex})/ ``` Unfortunately the regex check doesn't catch link-local addresses. It looks like the IPv6 regexes cannot process the zone ID suffix. (i.e. the interface number/name after the percentage sign, e.g. 'fe80::...**%8**' or 'fe80::...**%eth0**') As a result a regular resolving is attempted which fails (at least on my system) ---------------------------------------- Bug #17112: Resolv.getaddress fails with IPv6 link-local addresses https://bugs.ruby-lang.org/issues/17112#change-87014 * Author: daniel-rikowski (Daniel Rikowski) * Status: Open * Priority: Normal * ruby -v: ruby 2.7.1p83 (2020-03-31 revision a0c7c23c9c) [x64-mingw32] * Backport: 2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN ---------------------------------------- I noticed that I cannot resolve any link-local IPv6 address using `Resolv.getaddress`. For example calling `Resolv.getaddress('fe80::eca4:7b00:ecc5:206c%8')` fails with `Resolv::ResolvError` Resolving any IPv4 address succeedes, as well as resolving the loopback address `::1`. After some code digging I noticed that `Resolv::DNS` doesn't even attempt to resolve that IP address. It checks if there is any local IPv6 interface with an IP address which is not a loopback or a link-local address. ```ruby def each_address(name) each_resource(name, Resource::IN::A) {|resource| yield resource.address} if use_ipv6? # <===== false on my system each_resource(name, Resource::IN::AAAA) {|resource| yield resource.address} end end ``` `use_ipv6?` ultimately boils down to this: ```ruby Socket.ip_address_list.any? {|a| a.ipv6? && !a.ipv6_loopback? && !a.ipv6_linklocal? } ``` In other words if the system doesn't have a "real" IPv6 address, `Resolv.getaddress` cannot resolve link-local addresses. (`::1` is resolved using `Resolv::Hosts` which doesn't perform the same check) One could argue that IP addresses don't have to be resolved, and I could just perform a regex check and skip `Resolv.getaddress` if I already have an IP address. Unfortunately that is not possible when using `resolv-replace`. In that case most (all?) of Ruby's address resolving is piped through `Resolv.getaddress`. (That is how I noticed this bug: The RubyMine test runner uses drb which connects to a process on the same machine using a link-local IPv6 address. Since I'm using `resolv-replace` and I don't have a network interface with a non-loopback non-local-link address I encountered this bug.) Platform: ruby 2.7.1p83 (2020-03-31 revision a0c7c23c9c) [x64-mingw32] Microsoft Windows [Version 10.0.18363.959] -- https://bugs.ruby-lang.org/