Curl does use the ipv4 address if it doesn't receive the ipv6 address #11564
Description
I did this
Hi Team,
I am using curl 7.79.1 with c-ares 1.17.2.
I use this command "curl -v -m4 https://www.google.com" to test how curl responds in various changes in responses to dns queries made by curl. To do this i am using a very simple dns server which responds to queries which are only "www.google.com" .
The first case is i try to execute the above command what i notice is in this case is that both ipv4 and ipv6 queries are sent from the c-ares library. But if ipv6 is not received before the timeout occurs the command fails even though the ipv4 response is obtained .
curl -v -m4 https://www.google.com
-
STATE: INIT => CONNECT handle 0x563c74ff8998; line 1789 (connection #-5000)
-
Added connection 0. The cache now contains 1 members
15:29:38.735975 IP 6a5a2727f400.34325 > 10.174.75.167.domain: 63432+ A? www.google.com. (32)
15:29:38.736177 IP 6a5a2727f400.34325 > 10.174.75.167.domain: 56463+ AAAA? www.google.com. (32) -
STATE: CONNECT => RESOLVING handle 0x563c74ff8998; line 1835 (connection #0)
15:29:38.736618 IP 10.174.75.167.domain > 6a5a2727f400.34325: 63432 1/0/0 A 142.250.195.228 (49)*
15:29:38.736834 IP 10.174.75.167.domain > 6a5a2727f400.34325: 63432* 1/0/0 A 142.250.195.228 (49) -
Resolving timed out after 4001 milliseconds
-
multi_done
-
The cache now contains 0 members
-
Closing connection 0
-
Expire cleared (transfer 0x563c74ff8998)
curl: (28) Resolving timed out after 4001 milliseconds
Ok now what i do is i only try to send the ipv4 request using the -4 option but this also doesn't work with this curl version of 7.79.1.
curl -v -m4 -4 https://www.google.com
- STATE: INIT => CONNECT handle 0x565138d20998; line 1789 (connection #-5000)
- Added connection 0. The cache now contains 1 members
15:29:31.722618 IP 6a5a2727f400.38880 > 10.174.75.167.domain: 60498+ A? www.google.com. (32)
15:29:31.722853 IP 6a5a2727f400.38880 > 10.174.75.167.domain: 50175+ AAAA? www.google.com. (32) - STATE: CONNECT => RESOLVING handle 0x565138d20998; line 1835 (connection #0)
15:29:31.723211 IP 10.174.75.167.domain > 6a5a2727f400.38880: 60498* 1/0/0 A 142.250.195.228 (49)
15:29:31.723230 IP 10.174.75.167.domain > 6a5a2727f400.38880: 60498* 1/0/0 A 142.250.195.228 (49) - Resolving timed out after 4001 milliseconds
- multi_done
- The cache now contains 0 members
- Closing connection 0
- Expire cleared (transfer 0x565138d20998)
curl: (28) Resolving timed out after 4001 milliseconds
in this cases also both queries are sent out. Now if i do it just for ipv6 also the similar issue occurs both queries are sent out.
If i changed the curl version to 7.87.0 then the "-4" option works here it only sends the query for ipv4 and doesn't initiate for ipv6 . But even in that version if i execute "-6" option then both ipv4 and ipv6 dns queries are sent out.
Could you help me with this?
I expected the following
curl should return after the timeout and use what ever ip is obtained from the dns query response. To initiate the connection.
curl/libcurl version
root@6a5a2727f400:/# curl -V curl 7.79.1 (x86_64-pc-linux-gnu) libcurl/7.79.1 OpenSSL/1.1.1f c-ares/1.17.2 Release-Date: 2021-09-22 Protocols: dict file ftp ftps gopher gophers http https imap imaps mqtt pop3 pop3s rtsp smb smbs smtp smtps telnet tftp Features: alt-svc AsynchDNS Debug HSTS HTTPS-proxy IPv6 Largefile NTLM NTLM_WB SSL TLS-SRP TrackMemory UnixSockets
operating system
uname -a Linux 6a5a2727f400 5.4.0-136-generic #153~18.04.1-Ubuntu SMP Wed Nov 30 15:47:57 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux