[ruby-core:116448] [Ruby master Bug#20208] Net::HTTP errors with Errno::EAFNOSUPPORT when setting local_host with Addrinfo

["jprokop (Jarek Prokop) via ruby-core" <ruby-core@ml.ruby-lang.org>]

Issue #20208 has been updated by jprokop (Jarek Prokop).


I'll address each suggestion from my POV, though this is not my usual area of work. It sure is tricky.

1) I feel like this might bring more subtle bugs. I think you're right about also expecting that "localhost" should also work. Or expecting that "my_local" that is mapped on the host to the loopback will also work the same.
2) It does sound a bit daft, but it might be more reasonable implementation than 1).
3) On our side of Fedora, CentOS, ..., distros, the fix should be present in older glibc packages as a backport [0], so on downstream we should be able to revert the change and not hit that bug even without specifying the env variable. On upstream side? Not sure.

Hmm, perhaps Ruby could be smarter about the AF_* option? Not sure if it would or if it even be reasonable.

Reading the #19144 ticket, it seems the better solution would be imo for Ruby to not have to work around glibc bugs though.

[0] https://gitlab.com/redhat/centos-stream/rpms/glibc/-/blob/c8s/glibc-rh1868106-5.patch?ref_type=heads

----------------------------------------
Bug #20208: Net::HTTP errors with Errno::EAFNOSUPPORT when setting local_host with Addrinfo
https://bugs.ruby-lang.org/issues/20208#change-106472

* Author: jprokop (Jarek Prokop)
* Status: Assigned
* Priority: Normal
* Assignee: kjtsanaktsidis (KJ Tsanaktsidis)
* ruby -v: ruby 3.3.0 (2023-12-25 revision 5124f9ac75) [x86_64-linux]
* Backport: 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN
----------------------------------------
A bug was found when dealing with Ruby tests downstream. One of our builders has a specific networking configuration, resulting in Ruby incorrectly binding a socket, resulting in exception Errno::EAFNOSUPPORT,
despite localhost being IPv6 capable.

It is reproducible with Ruby 3.3, and reasonably current master (git hash a846d391d38b34fcc4f90adef967c166c923bd56).

Reproduction environment:
The networking configuration has to be in a specific state. The regular interface (such as eth0) has to have ipv6 disabled while localhost is IPv6 enabled.

I have tracked the problem to a commit adding AI_ADDRCONFIG flag: https://github.com/ruby/ruby/commit/d2ba8ea54a4089959afdeecdd963e3c4ff391748#diff-0a5f5e9afd3efff0444a367dd88aac41bb4de9765c8542b81c1ebcff60ab3b14R99
If I revert the commit or just simply set 2 ifdefs that are present in the diff with `HAVE_CONST_AI_ADDRCONFIG` to 0, the problem no longer occurs.

I have used vagrant with fedora/39-cloud-base box with the above mentioned git hash. However, I'd note that I reproduced it also on RHEL 8 and RHEL 9.

The VM has the following interfaces:
~~~
$ ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host noprefixroute
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 52:54:00:e3:aa:c1 brd ff:ff:ff:ff:ff:ff
    altname enp0s5
    altname ens5
    inet 192.168.122.209/24 brd 192.168.122.255 scope global dynamic noprefixroute eth0
       valid_lft 2099sec preferred_lft 2099sec
    inet6 fe80::f5fe:e8a4:8f83:4a8f/64 scope link tentative noprefixroute
       valid_lft forever preferred_lft forever
~~~

Disable IPv6 of eth0 and leave only lo with IPv6:
~~~
$ sudo sysctl "net.ipv6.conf.eth0.disable_ipv6=1"
~~~

Confirm the result:
~~~
$ ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host noprefixroute
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 52:54:00:e3:aa:c1 brd ff:ff:ff:ff:ff:ff
    altname enp0s5
    altname ens5
    inet 192.168.122.209/24 brd 192.168.122.255 scope global dynamic noprefixroute eth0
       valid_lft 3587sec preferred_lft 3587sec
~~~
inet6 is no longer present on eth0, but still present in lo.

Then we can copy what TestNetHTTPLocalBind is doing in setup, as that is one of the failing tests and use it for a reproducer:
~~~
$ ruby -rnet/http -e 'http = Net::HTTP.new("localhost", 8080); http.local_host = Addrinfo.tcp("localhost", 8080).ip_address; p http.get("/")'
/usr/share/ruby/net/http.rb:1603:in `initialize': Failed to open TCP connection to localhost:8080 (Address family not supported by protocol - bind(2) for "::1" port ) (Errno::EAFNOSUPPORT)
	from /usr/share/ruby/net/http.rb:1603:in `open'
	from /usr/share/ruby/net/http.rb:1603:in `block in connect'
	from /usr/share/ruby/timeout.rb:186:in `block in timeout'
	from /usr/share/ruby/timeout.rb:193:in `timeout'
	from /usr/share/ruby/net/http.rb:1601:in `connect'
	from /usr/share/ruby/net/http.rb:1580:in `do_start'
	from /usr/share/ruby/net/http.rb:1569:in `start'
	from /usr/share/ruby/net/http.rb:2297:in `request'
	from /usr/share/ruby/net/http.rb:1917:in `get'
	from -e:1:in `<main>'
/usr/share/ruby/net/http.rb:1603:in `initialize': Address family not supported by protocol - bind(2) for "::1" port  (Errno::EAFNOSUPPORT)
	from /usr/share/ruby/net/http.rb:1603:in `open'
	from /usr/share/ruby/net/http.rb:1603:in `block in connect'
	from /usr/share/ruby/timeout.rb:186:in `block in timeout'
	from /usr/share/ruby/timeout.rb:193:in `timeout'
	from /usr/share/ruby/net/http.rb:1601:in `connect'
	from /usr/share/ruby/net/http.rb:1580:in `do_start'
	from /usr/share/ruby/net/http.rb:1569:in `start'
	from /usr/share/ruby/net/http.rb:2297:in `request'
	from /usr/share/ruby/net/http.rb:1917:in `get'
	from -e:1:in `<main>'
~~~

The script:
~~~
http = Net::HTTP.new("localhost", 8080)
http.local_host = Addrinfo.tcp("localhost", 8080).ip_address

p http.get("/")
~~~
Without setting the `http.local_host` attribute using Addrinfo, the reproducer does not fail with EAFNOSUPPORT. Whether `port` is specified or `nil` does not make a difference.
Whether there is a server listening on 8080 or not does not make a difference, the script fails with the errno regardless. 

I have collected `strace` that points to a possible cause:
~~~
$ strace ruby -rnet/http -e 'http = Net::HTTP.new("localhost", 8080); http.local_host = Addrinfo.tcp("localhost", 8080).ip_address; p http.get("/")' 2>&1 | grep AF_INET
socket(AF_INET, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, IPPROTO_TCP) = 5
bind(5, {sa_family=AF_INET6, sin6_port=htons(0), sin6_flowinfo=htonl(0), inet_pton(AF_INET6, "::1", &sin6_addr), sin6_scope_id=0}, 28) = -1 EAFNOSUPPORT (Address family not supported by protocol)
~~~
A socket is created with AF_INET and later is bound with AF_INET6, that is not correct behavior as far as I can tell.
Full strace is attached.


Observed failures in Ruby test suite related to this issue:
~~~
109) Error:
TestNetHTTPLocalBind#test_bind_to_local_port:
Errno::EAFNOSUPPORT: Failed to open TCP connection to localhost:37337 (Address family not supported by protocol - bind(2) for "::1" port 45395)
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1603:in `initialize'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1603:in `open'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1603:in `block in connect'
    /builddir/build/BUILD/ruby-3.3.0/lib/timeout.rb:186:in `block in timeout'
    /builddir/build/BUILD/ruby-3.3.0/lib/timeout.rb:193:in `timeout'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1601:in `connect'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1580:in `do_start'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1569:in `start'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:2297:in `request'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1917:in `get'
    /builddir/build/BUILD/ruby-3.3.0/test/net/http/test_http.rb:1282:in `test_bind_to_local_port'
110) Error:
TestNetHTTPLocalBind#test_bind_to_local_host:
Errno::EAFNOSUPPORT: Failed to open TCP connection to localhost:46329 (Address family not supported by protocol - bind(2) for "::1" port )
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1603:in `initialize'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1603:in `open'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1603:in `block in connect'
    /builddir/build/BUILD/ruby-3.3.0/lib/timeout.rb:186:in `block in timeout'
    /builddir/build/BUILD/ruby-3.3.0/lib/timeout.rb:193:in `timeout'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1601:in `connect'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1580:in `do_start'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1569:in `start'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:2297:in `request'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1917:in `get'
    /builddir/build/BUILD/ruby-3.3.0/test/net/http/test_http.rb:1267:in `test_bind_to_local_host'
111) Error:
TestNetHTTPForceEncoding#test_response_body_encoding_false:
Errno::EAFNOSUPPORT: Failed to open TCP connection to localhost:41749 (Address family not supported by protocol - bind(2) for "::1" port )
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1603:in `initialize'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1603:in `open'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1603:in `block in connect'
    /builddir/build/BUILD/ruby-3.3.0/lib/timeout.rb:186:in `block in timeout'
    /builddir/build/BUILD/ruby-3.3.0/lib/timeout.rb:193:in `timeout'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1601:in `connect'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1580:in `do_start'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1569:in `start'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:2297:in `request'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1917:in `get'
    /builddir/build/BUILD/ruby-3.3.0/test/net/http/test_http.rb:1308:in `fe_request'
    /builddir/build/BUILD/ruby-3.3.0/test/net/http/test_http.rb:1312:in `test_response_body_encoding_false'
112) Error:
TestNetHTTPForceEncoding#test_response_body_encoding_string_without_content_type:
Errno::EAFNOSUPPORT: Failed to open TCP connection to localhost:42775 (Address family not supported by protocol - bind(2) for "::1" port )
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1603:in `initialize'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1603:in `open'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1603:in `block in connect'
    /builddir/build/BUILD/ruby-3.3.0/lib/timeout.rb:186:in `block in timeout'
    /builddir/build/BUILD/ruby-3.3.0/lib/timeout.rb:193:in `timeout'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1601:in `connect'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1580:in `do_start'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1569:in `start'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:2297:in `request'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1917:in `get'
    /builddir/build/BUILD/ruby-3.3.0/test/net/http/test_http.rb:1308:in `fe_request'
    /builddir/build/BUILD/ruby-3.3.0/test/net/http/test_http.rb:1330:in `test_response_body_encoding_string_without_content_type'
113) Error:
TestNetHTTPForceEncoding#test_response_body_encoding_true_with_content_type:
Errno::EAFNOSUPPORT: Failed to open TCP connection to localhost:36895 (Address family not supported by protocol - bind(2) for "::1" port )
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1603:in `initialize'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1603:in `open'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1603:in `block in connect'
    /builddir/build/BUILD/ruby-3.3.0/lib/timeout.rb:186:in `block in timeout'
    /builddir/build/BUILD/ruby-3.3.0/lib/timeout.rb:193:in `timeout'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1601:in `connect'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1580:in `do_start'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1569:in `start'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:2297:in `request'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1917:in `get'
    /builddir/build/BUILD/ruby-3.3.0/test/net/http/test_http.rb:1308:in `fe_request'
    /builddir/build/BUILD/ruby-3.3.0/test/net/http/test_http.rb:1324:in `test_response_body_encoding_true_with_content_type'
114) Error:
TestNetHTTPForceEncoding#test_response_body_encoding_encoding_without_content_type:
Errno::EAFNOSUPPORT: Failed to open TCP connection to localhost:37115 (Address family not supported by protocol - bind(2) for "::1" port )
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1603:in `initialize'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1603:in `open'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1603:in `block in connect'
    /builddir/build/BUILD/ruby-3.3.0/lib/timeout.rb:186:in `block in timeout'
    /builddir/build/BUILD/ruby-3.3.0/lib/timeout.rb:193:in `timeout'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1601:in `connect'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1580:in `do_start'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1569:in `start'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:2297:in `request'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1917:in `get'
    /builddir/build/BUILD/ruby-3.3.0/test/net/http/test_http.rb:1308:in `fe_request'
    /builddir/build/BUILD/ruby-3.3.0/test/net/http/test_http.rb:1336:in `test_response_body_encoding_encoding_without_content_type'
115) Error:
TestNetHTTPForceEncoding#test_response_body_encoding_true_without_content_type:
Errno::EAFNOSUPPORT: Failed to open TCP connection to localhost:37799 (Address family not supported by protocol - bind(2) for "::1" port )
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1603:in `initialize'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1603:in `open'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1603:in `block in connect'
    /builddir/build/BUILD/ruby-3.3.0/lib/timeout.rb:186:in `block in timeout'
    /builddir/build/BUILD/ruby-3.3.0/lib/timeout.rb:193:in `timeout'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1601:in `connect'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1580:in `do_start'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1569:in `start'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:2297:in `request'
    /builddir/build/BUILD/ruby-3.3.0/lib/net/http.rb:1917:in `get'
    /builddir/build/BUILD/ruby-3.3.0/test/net/http/test_http.rb:1308:in `fe_request'
    /builddir/build/BUILD/ruby-3.3.0/test/net/http/test_http.rb:1318:in `test_response_body_encoding_true_without_content_type'
~~~
Related failures from specs:
~~~
1)
An exception occurred during: before :each
TCPSocket#local_address using IPv6 using an implicit hostname the returned Addrinfo uses the correct IP address ERROR
Errno::ECONNREFUSED: Connection refused - connect(2) for nil port 37121
/builddir/build/BUILD/ruby-3.3.0/spec/ruby/library/socket/tcpsocket/local_address_spec.rb:59:in `initialize'
/builddir/build/BUILD/ruby-3.3.0/spec/ruby/library/socket/tcpsocket/local_address_spec.rb:59:in `new'
/builddir/build/BUILD/ruby-3.3.0/spec/ruby/library/socket/tcpsocket/local_address_spec.rb:59:in `block (4 levels) in <top (required)>'
/builddir/build/BUILD/ruby-3.3.0/spec/ruby/library/socket/tcpsocket/local_address_spec.rb:4:in `<top (required)>'
2)
An exception occurred during: before :each
TCPSocket#remote_address using IPv6 using an implicit hostname the returned Addrinfo uses the correct IP address ERROR
Errno::ECONNREFUSED: Connection refused - connect(2) for nil port 39823
/builddir/build/BUILD/ruby-3.3.0/spec/ruby/library/socket/tcpsocket/remote_address_spec.rb:58:in `initialize'
/builddir/build/BUILD/ruby-3.3.0/spec/ruby/library/socket/tcpsocket/remote_address_spec.rb:58:in `new'
/builddir/build/BUILD/ruby-3.3.0/spec/ruby/library/socket/tcpsocket/remote_address_spec.rb:58:in `block (4 levels) in <top (required)>'
/builddir/build/BUILD/ruby-3.3.0/spec/ruby/library/socket/tcpsocket/remote_address_spec.rb:4:in `<top (required)>'
~~~


---Files--------------------------------
strace_log.txt (304 KB)


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