curl aborts after half of the connection timeout

[mkauf]

The connection timeout handling is broken since commit dbd16c3 (found this commit with git bisect).

I did this

time curl --connect-timeout 10 http://my-server:11223/

my-server is a special system that drops everything on port 11223. iptables rule on this server: iptables -A INPUT -p tcp --destination-port 11223 -j DROP. It has an IPv4 address and an IPv6 address.

Before the mentioned commit (curl <= 7.69.1):

curl: (28) Connection timed out after 10001 milliseconds

real	0m10.004s
user	0m0.002s
sys	0m0.001s

-> that's expected

After the mentioned commit:

curl: (28) Failed to connect to my-server port 11223: Connection timed out

real	0m5.205s
user	0m0.000s
sys	0m0.003s

5.2 seconds = (connection timeout) / 2 + (happy eyeballs timeout)

Current master:

curl: (28) Failed to connect to my-server port 11223 after 5000 ms: Timeout was reached

real	0m5.002s
user	0m0.000s
sys	0m0.003s

I expected the following

curl aborts after the connection timeout (10 seconds) and not after half of the connection timeout (5 seconds)

curl/libcurl version

curl 7.87.1-DEV (x86_64-pc-linux-gnu) libcurl/7.87.1-DEV nghttp2/1.51.0
Release-Date: [unreleased]
Protocols: dict file ftp gopher http imap mqtt pop3 rtsp smtp telnet tftp
Features: alt-svc AsynchDNS HTTP2 IPv6 Largefile threadsafe UnixSockets

operating system

Linux myhost 6.1.10-100.fc36.x86_64 #1 SMP PREEMPT_DYNAMIC Mon Feb 6 19:58:39 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux

[icing]

@mkauf: would you be able to run #10517 in your setup? I found cases where the effective connect timeout was halfed.

[mkauf]

@icing : Yes, I have tested it. Your pull request fixes this bug 👍