From bb73dc304246c8b971493887ae2ebb96bc0a7a46 Mon Sep 17 00:00:00 2001
From: Yannick Dylla <17772145+ydylla@users.noreply.github.com>
Date: Sun, 2 Jun 2024 22:24:49 +0200
Subject: [PATCH] fix: skip already seen routes after a match

This is done to be backwards compatible with the old matching behavior see https://github.com/mholt/caddy-l4/pull/192#issuecomment-2143681952
---
 layer4/routes.go | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/layer4/routes.go b/layer4/routes.go
index 97f55bd..c1d002a 100644
--- a/layer4/routes.go
+++ b/layer4/routes.go
@@ -101,6 +101,7 @@ func (routes RouteList) Provision(ctx caddy.Context) error {
 func (routes RouteList) Compile(logger *zap.Logger, matchingTimeout time.Duration, next NextHandler) Handler {
 	return HandlerFunc(func(cx *Connection) error {
 		deadline := time.Now().Add(matchingTimeout)
+		lastMatchedRouteIdx := -1
 	router:
 		// timeout matching to protect against malicious or very slow clients
 		err := cx.Conn.SetReadDeadline(deadline)
@@ -127,7 +128,14 @@ func (routes RouteList) Compile(logger *zap.Logger, matchingTimeout time.Duratio
 				}
 			}
 
-			for _, route := range routes {
+			for i, route := range routes {
+				// After a match continue with the routes after the matched one, instead of starting at the beginning.
+				// This is done for backwards compatibility with configs written before the "Non blocking matchers & matching timeout" rewrite.
+				// See https://github.com/mholt/caddy-l4/pull/192 and https://github.com/mholt/caddy-l4/pull/192#issuecomment-2143681952.
+				if i <= lastMatchedRouteIdx {
+					continue
+				}
+
 				// A route must match at least one of the matcher sets
 				matched, err := route.matcherSets.AnyMatch(cx)
 				if errors.Is(err, ErrConsumedAllPrefetchedBytes) {
@@ -138,6 +146,8 @@ func (routes RouteList) Compile(logger *zap.Logger, matchingTimeout time.Duratio
 					return nil
 				}
 				if matched {
+					lastMatchedRouteIdx = i
+
 					// remove deadline after we matched
 					err = cx.Conn.SetReadDeadline(time.Time{})
 					if err != nil {