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auth: login: explicit check for ipv6 port bindings #1251

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auth: login: explicit check for ipv6 port bindings #1251

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12 changes: 9 additions & 3 deletions internal/pkg/auth/user_login.go
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Original file line number Diff line number Diff line change
Expand Up @@ -95,9 +95,15 @@ func AuthorizeUser(p *print.Printer, isReauthentication bool) error {
var port int
for i := range configuredPortRange {
port = defaultPort + i
portString := fmt.Sprintf(":%s", strconv.Itoa(port))
addr4 := fmt.Sprintf("127.0.0.1:%d", port)
addr6 := fmt.Sprintf("[::1]:%d", port)
p.Debug(print.DebugLevel, "trying to bind port %d for login redirect", port)
listener, listenerErr = net.Listen("tcp", portString)
ipv6Listener, ipv6ListenerErr := net.Listen("tcp6", addr6)
if ipv6ListenerErr != nil {
continue
}
_ = ipv6Listener.Close()
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@cgoetz-inovex cgoetz-inovex Mar 4, 2026

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potential race condition:
If after this line another service binds to [::1]:{port} we have the same situation as before.

listener, listenerErr = net.Listen("tcp4", addr4)
if listenerErr == nil {
redirectURL = fmt.Sprintf("http://localhost:%d", port)
p.Debug(print.DebugLevel, "bound port %d for login redirect", port)
Expand All @@ -106,7 +112,7 @@ func AuthorizeUser(p *print.Printer, isReauthentication bool) error {
p.Debug(print.DebugLevel, "unable to bind port %d for login redirect: %s", port, listenerErr)
}
if listenerErr != nil {
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@marceljk marceljk Mar 4, 2026

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this should be extended with a check if ipv6ListenerErr is not nil. It's probably unlikely, but if someone uses already all the ports from 8000-8020, it will continue here without an error and try the authentication flow without an redirect url and the CLI will stop with a panic.

I extended your python code, to simulate this case

#!/usr/bin/env python3
import threading
from http.server import HTTPServer, SimpleHTTPRequestHandler
import socket

HOST = "::1"
PORT = 8000


class IPv6HTTPServer(HTTPServer):
   address_family = socket.AF_INET6

for i in range(0, 21):
   server = IPv6HTTPServer((HOST, PORT + i), SimpleHTTPRequestHandler)
   print(f"Serving on http://[{HOST}]:{PORT+i}")
   t = threading.Thread(target=server.serve_forever)
   t.start()

return fmt.Errorf("unable to bind port for login redirect, tried from port %d to %d: %w", defaultPort, port, err)
return fmt.Errorf("unable to bind port for login redirect, tried from port %d to %d: %w", defaultPort, port, listenerErr)
}

conf := &oauth2.Config{
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