caddyhttp: Implement named routes, `invoke` directive (#5107)

* caddyhttp: Implement named routes, `invoke` directive

* gofmt

* Add experimental marker

* Adjust route compile comments

3 files changed, 134 insertions, 2 deletions

diff --git a/caddyconfig/httpcaddyfile/builtins.go b/caddyconfig/httpcaddyfile/builtins.go
index 45da4a8..d6cdf84 100644
--- a/caddyconfig/httpcaddyfile/builtins.go
+++ b/caddyconfig/httpcaddyfile/builtins.go
@@ -48,6 +48,7 @@ func init() {
 	RegisterHandlerDirective("route", parseRoute)
 	RegisterHandlerDirective("handle", parseHandle)
 	RegisterDirective("handle_errors", parseHandleErrors)
+	RegisterHandlerDirective("invoke", parseInvoke)
 	RegisterDirective("log", parseLog)
 	RegisterHandlerDirective("skip_log", parseSkipLog)
 }
@@ -764,6 +765,27 @@ func parseHandleErrors(h Helper) ([]ConfigValue, error) {
 	}, nil
 }
 
+// parseInvoke parses the invoke directive.
+func parseInvoke(h Helper) (caddyhttp.MiddlewareHandler, error) {
+	h.Next() // consume directive
+	if !h.NextArg() {
+		return nil, h.ArgErr()
+	}
+	for h.Next() || h.NextBlock(0) {
+		return nil, h.ArgErr()
+	}
+
+	// remember that we're invoking this name
+	// to populate the server with these named routes
+	if h.State[namedRouteKey] == nil {
+		h.State[namedRouteKey] = map[string]struct{}{}
+	}
+	h.State[namedRouteKey].(map[string]struct{})[h.Val()] = struct{}{}
+
+	// return the handler
+	return &caddyhttp.Invoke{Name: h.Val()}, nil
+}
+
 // parseLog parses the log directive. Syntax:
 //
 //	log {
diff --git a/caddyconfig/httpcaddyfile/directives.go b/caddyconfig/httpcaddyfile/directives.go
index b8faa4a..1223013 100644
--- a/caddyconfig/httpcaddyfile/directives.go
+++ b/caddyconfig/httpcaddyfile/directives.go
@@ -65,6 +65,7 @@ var directiveOrder = []string{
 	"templates",
 
 	// special routing & dispatching directives
+	"invoke",
 	"handle",
 	"handle_path",
 	"route",
diff --git a/caddyconfig/httpcaddyfile/httptype.go b/caddyconfig/httpcaddyfile/httptype.go
index 90c90ee..c7aeb94 100644
--- a/caddyconfig/httpcaddyfile/httptype.go
+++ b/caddyconfig/httpcaddyfile/httptype.go
@@ -52,8 +52,10 @@ type ServerType struct {
 }
 
 // Setup makes a config from the tokens.
-func (st ServerType) Setup(inputServerBlocks []caddyfile.ServerBlock,
-	options map[string]any) (*caddy.Config, []caddyconfig.Warning, error) {
+func (st ServerType) Setup(
+	inputServerBlocks []caddyfile.ServerBlock,
+	options map[string]any,
+) (*caddy.Config, []caddyconfig.Warning, error) {
 	var warnings []caddyconfig.Warning
 	gc := counter{new(int)}
 	state := make(map[string]any)
@@ -79,6 +81,11 @@ func (st ServerType) Setup(inputServerBlocks []caddyfile.ServerBlock,
 		return nil, warnings, err
 	}
 
+	originalServerBlocks, err = st.extractNamedRoutes(originalServerBlocks, options, &warnings)
+	if err != nil {
+		return nil, warnings, err
+	}
+
 	// replace shorthand placeholders (which are convenient
 	// when writing a Caddyfile) with their actual placeholder
 	// identifiers or variable names
@@ -172,6 +179,18 @@ func (st ServerType) Setup(inputServerBlocks []caddyfile.ServerBlock,
 				result.directive = dir
 				sb.pile[result.Class] = append(sb.pile[result.Class], result)
 			}
+
+			// specially handle named routes that were pulled out from
+			// the invoke directive, which could be nested anywhere within
+			// some subroutes in this directive; we add them to the pile
+			// for this server block
+			if state[namedRouteKey] != nil {
+				for name := range state[namedRouteKey].(map[string]struct{}) {
+					result := ConfigValue{Class: namedRouteKey, Value: name}
+					sb.pile[result.Class] = append(sb.pile[result.Class], result)
+				}
+				state[namedRouteKey] = nil
+			}
 		}
 	}
 
@@ -403,6 +422,77 @@ func (ServerType) evaluateGlobalOptionsBlock(serverBlocks []serverBlock, options
 	return serverBlocks[1:], nil
 }
 
+// extractNamedRoutes pulls out any named route server blocks
+// so they don't get parsed as sites, and stores them in options
+// for later.
+func (ServerType) extractNamedRoutes(
+	serverBlocks []serverBlock,
+	options map[string]any,
+	warnings *[]caddyconfig.Warning,
+) ([]serverBlock, error) {
+	namedRoutes := map[string]*caddyhttp.Route{}
+
+	gc := counter{new(int)}
+	state := make(map[string]any)
+
+	// copy the server blocks so we can
+	// splice out the named route ones
+	filtered := append([]serverBlock{}, serverBlocks...)
+	index := -1
+
+	for _, sb := range serverBlocks {
+		index++
+		if !sb.block.IsNamedRoute {
+			continue
+		}
+
+		// splice out this block, because we know it's not a real server
+		filtered = append(filtered[:index], filtered[index+1:]...)
+		index--
+
+		if len(sb.block.Segments) == 0 {
+			continue
+		}
+
+		// zip up all the segments since ParseSegmentAsSubroute
+		// was designed to take a directive+
+		wholeSegment := caddyfile.Segment{}
+		for _, segment := range sb.block.Segments {
+			wholeSegment = append(wholeSegment, segment...)
+		}
+
+		h := Helper{
+			Dispenser:    caddyfile.NewDispenser(wholeSegment),
+			options:      options,
+			warnings:     warnings,
+			matcherDefs:  nil,
+			parentBlock:  sb.block,
+			groupCounter: gc,
+			State:        state,
+		}
+
+		handler, err := ParseSegmentAsSubroute(h)
+		if err != nil {
+			return nil, err
+		}
+		subroute := handler.(*caddyhttp.Subroute)
+		route := caddyhttp.Route{}
+
+		if len(subroute.Routes) == 1 && len(subroute.Routes[0].MatcherSetsRaw) == 0 {
+			// if there's only one route with no matcher, then we can simplify
+			route.HandlersRaw = append(route.HandlersRaw, subroute.Routes[0].HandlersRaw[0])
+		} else {
+			// otherwise we need the whole subroute
+			route.HandlersRaw = []json.RawMessage{caddyconfig.JSONModuleObject(handler, "handler", subroute.CaddyModule().ID.Name(), h.warnings)}
+		}
+
+		namedRoutes[sb.block.Keys[0]] = &route
+	}
+	options["named_routes"] = namedRoutes
+
+	return filtered, nil
+}
+
 // serversFromPairings creates the servers for each pairing of addresses
 // to server blocks. Each pairing is essentially a server definition.
 func (st *ServerType) serversFromPairings(
@@ -542,6 +632,24 @@ func (st *ServerType) serversFromPairings(
 			}
 		}
 
+		// add named routes to the server if 'invoke' was used inside of it
+		configuredNamedRoutes := options["named_routes"].(map[string]*caddyhttp.Route)
+		for _, sblock := range p.serverBlocks {
+			if len(sblock.pile[namedRouteKey]) == 0 {
+				continue
+			}
+			for _, value := range sblock.pile[namedRouteKey] {
+				if srv.NamedRoutes == nil {
+					srv.NamedRoutes = map[string]*caddyhttp.Route{}
+				}
+				name := value.Value.(string)
+				if configuredNamedRoutes[name] == nil {
+					return nil, fmt.Errorf("cannot invoke named route '%s', which was not defined", name)
+				}
+				srv.NamedRoutes[name] = configuredNamedRoutes[name]
+			}
+		}
+
 		// create a subroute for each site in the server block
 		for _, sblock := range p.serverBlocks {
 			matcherSetsEnc, err := st.compileEncodedMatcherSets(sblock)
@@ -1469,6 +1577,7 @@ type sbAddrAssociation struct {
 }
 
 const matcherPrefix = "@"
+const namedRouteKey = "named_route"
 
 // Interface guard
 var _ caddyfile.ServerType = (*ServerType)(nil)