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

* caddyhttp: Implement named routes, `invoke` directive

* gofmt

* Add experimental marker

* Adjust route compile comments

4 files changed, 176 insertions, 10 deletions

diff --git a/caddyconfig/caddyfile/parse.go b/caddyconfig/caddyfile/parse.go
index ab84086..64d1062 100644
--- a/caddyconfig/caddyfile/parse.go
+++ b/caddyconfig/caddyfile/parse.go
@@ -148,7 +148,6 @@ func (p *parser) begin() error {
 	}
 
 	err := p.addresses()
-
 	if err != nil {
 		return err
 	}
@@ -159,6 +158,25 @@ func (p *parser) begin() error {
 		return nil
 	}
 
+	if ok, name := p.isNamedRoute(); ok {
+		// named routes only have one key, the route name
+		p.block.Keys = []string{name}
+		p.block.IsNamedRoute = true
+
+		// we just need a dummy leading token to ease parsing later
+		nameToken := p.Token()
+		nameToken.Text = name
+
+		// get all the tokens from the block, including the braces
+		tokens, err := p.blockTokens(true)
+		if err != nil {
+			return err
+		}
+		tokens = append([]Token{nameToken}, tokens...)
+		p.block.Segments = []Segment{tokens}
+		return nil
+	}
+
 	if ok, name := p.isSnippet(); ok {
 		if p.definedSnippets == nil {
 			p.definedSnippets = map[string][]Token{}
@@ -167,7 +185,7 @@ func (p *parser) begin() error {
 			return p.Errf("redeclaration of previously declared snippet %s", name)
 		}
 		// consume all tokens til matched close brace
-		tokens, err := p.snippetTokens()
+		tokens, err := p.blockTokens(false)
 		if err != nil {
 			return err
 		}
@@ -576,6 +594,15 @@ func (p *parser) closeCurlyBrace() error {
 	return nil
 }
 
+func (p *parser) isNamedRoute() (bool, string) {
+	keys := p.block.Keys
+	// A named route block is a single key with parens, prefixed with &.
+	if len(keys) == 1 && strings.HasPrefix(keys[0], "&(") && strings.HasSuffix(keys[0], ")") {
+		return true, strings.TrimSuffix(keys[0][2:], ")")
+	}
+	return false, ""
+}
+
 func (p *parser) isSnippet() (bool, string) {
 	keys := p.block.Keys
 	// A snippet block is a single key with parens. Nothing else qualifies.
@@ -586,18 +613,24 @@ func (p *parser) isSnippet() (bool, string) {
 }
 
 // read and store everything in a block for later replay.
-func (p *parser) snippetTokens() ([]Token, error) {
-	// snippet must have curlies.
+func (p *parser) blockTokens(retainCurlies bool) ([]Token, error) {
+	// block must have curlies.
 	err := p.openCurlyBrace()
 	if err != nil {
 		return nil, err
 	}
-	nesting := 1 // count our own nesting in snippets
+	nesting := 1 // count our own nesting
 	tokens := []Token{}
+	if retainCurlies {
+		tokens = append(tokens, p.Token())
+	}
 	for p.Next() {
 		if p.Val() == "}" {
 			nesting--
 			if nesting == 0 {
+				if retainCurlies {
+					tokens = append(tokens, p.Token())
+				}
 				break
 			}
 		}
@@ -617,9 +650,10 @@ func (p *parser) snippetTokens() ([]Token, error) {
 // head of the server block with tokens, which are
 // grouped by segments.
 type ServerBlock struct {
-	HasBraces bool
-	Keys      []string
-	Segments  []Segment
+	HasBraces    bool
+	Keys         []string
+	Segments     []Segment
+	IsNamedRoute bool
 }
 
 // DispenseDirective returns a dispenser that contains
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)