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From: matthew@kerwin.net.au
To: ruby-core@ruby-lang.org
Subject: [ruby-core:99424] [Ruby master Bug#15773] Net::HTTP doesn't try next IP address in case of timeout
Date: Fri, 31 Jul 2020 22:51:28 +0000 (UTC)
Message-ID: <redmine.journal-86877.20200731225127.10577@ruby-lang.org> (raw)
In-Reply-To: <redmine.issue-15773.20190416231201.10577@ruby-lang.org>

Issue #15773 has been updated by phluid61 (Matthew Kerwin).


benlangfeld (Ben Langfeld) wrote in #note-4:
> 
> RFC3484 (https://www.ietf.org/rfc/rfc3484.txt) very clearly states:
> 

Minor point, I don't think it affects much, but RFC 3484 is obsolete and is replaced by RFC 6724 https://tools.ietf.org/html/rfc6724

Cheers

----------------------------------------
Bug #15773: Net::HTTP doesn't try next IP address in case of timeout
https://bugs.ruby-lang.org/issues/15773#change-86877

* Author: nicolasnoble (Nicolas Noble)
* Status: Rejected
* Priority: Normal
* Backport: 2.4: UNKNOWN, 2.5: UNKNOWN, 2.6: UNKNOWN
----------------------------------------
This example requires to have a working IPv6 address. Since IPv6 is used in first priority, I am using it to demonstrate the problem, but it exists with plain IPv4, which will be more round-robin-style, so less deterministic to show a reproduction case. I have made two URLs that have both IPv4 and IPv6 addresses: http://ipv6.grumpycoder.net/ and http://bad-ipv6.grumpycoder.net/ - both URLs should work in an IPv6-enabled web browser, as well as curl or wget for instance. The difference is that the bad-ipv6 subdomain doesn't have an IPv6 that will actually connect. Therefore, browsers, curl and wget will fallback to using the IPv4 when the initial IPv6 connection attempt failed:

```
$ wget -T1 http://bad-ipv6.grumpycoder.net -O - # demonstrating using wget because its output is more clear than curl's verbose
--2019-04-16 15:56:52--  http://bad-ipv6.grumpycoder.net/
Resolving bad-ipv6.grumpycoder.net (bad-ipv6.grumpycoder.net)... 2001:bc8:3690:200::2, 62.210.214.144
Connecting to bad-ipv6.grumpycoder.net (bad-ipv6.grumpycoder.net)|2001:bc8:3690:200::2|:80... failed: Connection timed out.
Connecting to bad-ipv6.grumpycoder.net (bad-ipv6.grumpycoder.net)|62.210.214.144|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 45 [text/html]
Saving to: ‘STDOUT’

-                                      0%[                                                                      ]       0  --.-KB/s               <html><body><h1>It works!</h1></body></html>
-                                    100%[=====================================================================>]      45  --.-KB/s    in 0s

2019-04-16 15:56:53 (6.55 MB/s) - written to stdout [45/45]

```

However, in Ruby, using Net::HTTP (or OpenURI), that's not going to be the case:

```
$ ruby bad-ipv6.rb
http://ipv6.grumpycoder.net
<html><body><h1>It works!</h1></body></html>
http://bad-ipv6.grumpycoder.net
Net::OpenTimeout: execution expired
```

Contents of my test file:

```ruby
require 'open-uri'

['ipv6', 'bad-ipv6'].each do |s|
  url = 'http://%s.grumpycoder.net' %[s]
  puts url
  begin
    puts open(url).read
  rescue StandardError => e
    puts "#{e.class}: #{e.message}"
    next
  end
end
```

The proper behavior should be to retry the next IP address and exhaust all of the IPs in the DNS resolution results before throwing out an error.



-- 
https://bugs.ruby-lang.org/

  parent reply index

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <redmine.issue-15773.20190416231201.10577@ruby-lang.org>
2020-07-28 23:59 ` [ruby-core:99381] " oded
2020-07-31 18:46 ` [ruby-core:99423] " ben
2020-07-31 22:51 ` matthew [this message]
2020-08-03 16:23 ` [ruby-core:99456] " ben

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