Windows: '--local-port range' is unable to detect ports in TIME_WAIT, and so does not reliably try further ports in the range #8112
Description
I did this
On a Windows client:
The first run succeeds:
> curl -v --local-port 600-605 http://github.com/
* Trying 140.82.121.4:80...
* Local port: 600
* Connected to github.com (140.82.121.4) port 80 (#0)
[...]
The same command a second time fails:
> curl -v --local-port 600-605 http://github.com/
* Trying 140.82.121.4:80...
* Local port: 600
* connect to 140.82.121.4 port 80 failed: Address already in use
* Failed to connect to github.com port 80 after 13 ms: Address already in use
* Closing connection 0
curl: (7) Failed to connect to github.com port 80 after 13 ms: Address already in use
[...]
I expected the following
On a Linux client, both runs succeed:
First, port 600 is used:
# curl -v --local-port 600-605 http://github.com/
* Trying 140.82.121.4...
* TCP_NODELAY set
* Local port: 600
* Connected to github.com (140.82.121.4) port 80 (#0)
[...]
And on the second execution, port 601 is used:
# curl -v --local-port 600-605 http://github.com/
* Trying 140.82.121.4...
* TCP_NODELAY set
* Bind to local port 600 failed, trying next
* Local port: 601
* Connected to github.com (140.82.121.4) port 80 (#0)
[...]
It appears that given an already in-use port number (as seen through netstat / ss), Windows bind will succeed (then failing later on the connect call), whilst Linux bind will not succeed. Curl's localport "try next" logic considers only whether the bind call succeeds.
curl/libcurl version
curl 7.80.0 (x86_64-pc-win32) libcurl/7.80.0 OpenSSL/3.0.0 (Schannel) zlib/1.2.11 brotli/1.0.9 zstd/1.5.0 libidn2/2.3.2 libssh2/1.10.0 nghttp2/1.46.0 libgsasl/1.10.0
Release-Date: 2021-11-10
Protocols: dict file ftp ftps gopher gophers http https imap imaps ldap ldaps mqtt pop3 pop3s rtsp scp sftp smb smbs smtp smtps telnet tftp
Features: alt-svc AsynchDNS brotli gsasl HSTS HTTP2 HTTPS-proxy IDN IPv6 Kerberos Largefile libz MultiSSL NTLM SPNEGO SSL SSPI TLS-SRP UnixSockets zstd
operating system
Windows 10 Version 20H2 (OS Build 19042.1348)