A route may have its own listener: every request there is that route, paths unprefixed

Implemented-By: OpenCode session (model recorded in docs/implementer-log.md)

internal/config/listen_test.go

@@ -0,0 +1,54 @@
+package config_test
+
+// v2.3 task 03: a concrete route may own a dedicated listener. Every request that arrives on it is
+// that route, with the upstream path unprefixed, for clients that cannot put a route in the path
+// or a header (Boxmaker's inferproxy rewrites nothing).
+
+import (
+	"strings"
+	"testing"
+
+	"git.wntrmute.dev/kyle/crossbar/internal/config"
+)
+
+const listenBase = `
+listen = "127.0.0.1:7777"
+[hosts.a]
+base_url = "http://a:1"
+models = { "m" = { } }
+[routes.bm-a]
+hosts = ["a"]
+listen = "127.0.0.1:7801"
+[routes.bm-b]
+hosts = ["a"]
+listen = "127.0.0.1:7802"
+[routes.plain]
+hosts = ["a"]
+`
+
+func TestRouteListen(t *testing.T) {
+	c, err := config.Parse(strings.NewReader(listenBase))
+	if err != nil {
+		t.Fatal(err)
+	}
+	for route, want := range map[string]string{"bm-a": "127.0.0.1:7801", "bm-b": "127.0.0.1:7802", "plain": ""} {
+		if got := c.Routes[route].Listen; got != want {
+			t.Errorf("%s listen = %q, want %q", route, got, want)
+		}
+	}
+}
+
+func TestRouteListenRejected(t *testing.T) {
+	for _, tc := range []struct{ name, text, want string }{
+		{"not host:port", strings.Replace(listenBase, `"127.0.0.1:7801"`, `"7801"`, 1), "routes.bm-a.listen"},
+		{"bad port", strings.Replace(listenBase, `"127.0.0.1:7801"`, `"127.0.0.1:http"`, 1), "routes.bm-a.listen"},
+		{"port zero", strings.Replace(listenBase, `"127.0.0.1:7801"`, `"127.0.0.1:0"`, 1), "routes.bm-a.listen"},
+		{"same as another route", strings.Replace(listenBase, `"127.0.0.1:7802"`, `"127.0.0.1:7801"`, 1), "listen"},
+		{"same as the main listener", strings.Replace(listenBase, `"127.0.0.1:7801"`, `"127.0.0.1:7777"`, 1), "routes.bm-a.listen"},
+		{"on a template", listenBase + "[routes.\"t-*\"]\nhosts = [\"a\"]\nlisten = \"127.0.0.1:7803\"\n", "t-*"},
+	} {
+		if _, err := config.Parse(strings.NewReader(tc.text)); err == nil || !strings.Contains(err.Error(), tc.want) {
+			t.Errorf("%s: err %v, want one containing %q", tc.name, err, tc.want)
+		}
+	}
+}

internal/config/route.go

@@ -2,8 +2,10 @@ package config
 
 import (
 	"fmt"
+	"net"
 	"regexp"
 	"sort"
+	"strconv"
 	"strings"
 )
 
@@ -22,6 +24,7 @@ type Route struct {
 	Peers        []string `toml:"peers"`
 	Affinity     string   `toml:"affinity"` // "" or "conversation" (the default), or "route"
 	Queue        *bool    `toml:"queue"`    // nil means true
+	Listen       string   `toml:"listen"`   // "" = none; else host:port of the route's own listener
 }
 
 // PerRoute reports affinity = "route": every request on the route (chat or control) shares one
@@ -80,6 +83,9 @@ func (c *Config) checkRoutes(peersDefined map[string]bool, identityDefined bool)
 		names = append(names, name)
 	}
 	sort.Strings(names)
+	// A route's own listener address, keyed for the uniqueness check: the value is the
+	// route that first claimed it, so the second route in sorted order reports the miss.
+	seenListen := make(map[string]string, len(c.Routes))
 	for _, name := range names {
 		r := c.Routes[name]
 
@@ -124,6 +130,39 @@ func (c *Config) checkRoutes(peersDefined map[string]bool, identityDefined bool)
 		if e := checkPeers(name, r.Peers, peersDefined[name], identityDefined, c.Identity); e != nil {
 			return e
 		}
+
+		if e := checkListen(name, r.Listen, c.Listen, seenListen); e != nil {
+			return e
+		}
 	}
 	return nil
 }
+
+// checkListen validates one route's own listener. The rules, in order, each naming the key
+// routes.<name>.listen: the value must split into host and a numeric port 1-65535, it must not be on
+// a template route, it must not be the top-level listen, and it must be unique across routes (the
+// second route in sorted name order reports the clash and the other route's name).
+func checkListen(name, listen, mainListen string, seenListen map[string]string) *Error {
+	if listen == "" {
+		return nil
+	}
+	_, port, err := net.SplitHostPort(listen)
+	if err != nil {
+		return &Error{Field: fmt.Sprintf("routes.%s.listen", name), Msg: "must be host:port"}
+	}
+	n, err := strconv.Atoi(port)
+	if err != nil || n < 1 || n > 65535 {
+		return &Error{Field: fmt.Sprintf("routes.%s.listen", name), Msg: "port must be 1-65535"}
+	}
+	if templateName.MatchString(name) {
+		return &Error{Field: fmt.Sprintf("routes.%s.listen", name), Msg: "a template route cannot have its own listener"}
+	}
+	if listen == mainListen {
+		return &Error{Field: fmt.Sprintf("routes.%s.listen", name), Msg: "cannot be the main listen address"}
+	}
+	if other, dup := seenListen[listen]; dup {
+		return &Error{Field: fmt.Sprintf("routes.%s.listen", name), Msg: fmt.Sprintf("already used by route %s", other)}
+	}
+	seenListen[listen] = name
+	return nil
+}