Files
probo/pkg/netx/netx.go
Bryan Frimin 5b92a7ba5a Allow ephemeral ports for loopback redirect URIs
Native OAuth clients such as Claude Code publish loopback redirect URIs
without a port (http://localhost/callback) and pick an ephemeral port at
request time, as described in RFC 8252 section 7.3. The authorize flow
matched the requested redirect URI against the registered set with an
exact string comparison, so http://localhost:3118/callback was rejected
with invalid_redirect_uri even for a trusted, allow-listed client.

Make OAuth2Client.IsRedirectURIAllowed the single source of truth for
redirect matching: it keeps exact matching and adds loopback-aware
matching that ignores the port when scheme, host, path, and query agree.
The redundant document-level check and its duplicate loopback helper in
the CIMD resolver are removed, so both the registered-client and CIMD
paths now rely on one matcher.

Also add a pkg/netx package for the loopback helper.

Signed-off-by: Bryan Frimin <bryan@probo.com>
2026-06-30 18:36:47 +02:00

32 lines
1.2 KiB
Go

// Copyright (c) 2026 Probo Inc <hello@probo.com>.
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
// OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
// PERFORMANCE OF THIS SOFTWARE.
package netx
import "net"
// IsLoopback reports whether host is a loopback address. It recognizes
// "localhost" by name and delegates to net.IP.IsLoopback for IP addresses,
// which covers 127.0.0.0/8, ::1, and IPv4-mapped variants like
// ::ffff:127.0.0.1.
func IsLoopback(host string) bool {
if host == "localhost" {
return true
}
ip := net.ParseIP(host)
return ip != nil && ip.IsLoopback()
}