Refactor Caddyfile adapter and module registration

Use piles from which to draw config values.

Module values can return their name, so now we can do two-way mapping
from value to name and name to value; whereas before we could only map
name to value. This was problematic with the Caddyfile adapter since
it receives values and needs to know the name to put in the config.

1 files changed, 182 insertions, 0 deletions

diff --git a/caddyconfig/httpcaddyfile/directives.go b/caddyconfig/httpcaddyfile/directives.go
new file mode 100644
index 0000000..526ac87
--- /dev/null
+++ b/caddyconfig/httpcaddyfile/directives.go
@@ -0,0 +1,182 @@
+// Copyright 2015 Matthew Holt and The Caddy Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package httpcaddyfile
+
+import (
+	"encoding/json"
+
+	"github.com/caddyserver/caddy/v2"
+	"github.com/caddyserver/caddy/v2/caddyconfig"
+	"github.com/caddyserver/caddy/v2/caddyconfig/caddyfile"
+	"github.com/caddyserver/caddy/v2/modules/caddyhttp"
+)
+
+// defaultDirectiveOrder specifies the order
+// to apply directives in HTTP routes.
+// TODO: finish the ability to customize this
+var defaultDirectiveOrder = []string{
+	"rewrite",
+	"try_files",
+	"headers",
+	"encode",
+	"templates",
+	"redir",
+	"static_response", // TODO: "reply" or "respond"?
+	"reverse_proxy",
+	"file_server",
+}
+
+// RegisterDirective registers a unique directive dir with an
+// associated unmarshaling (setup) function. When directive dir
+// is encountered in a Caddyfile, setupFunc will be called to
+// unmarshal its tokens.
+func RegisterDirective(dir string, setupFunc UnmarshalFunc) {
+	if _, ok := registeredDirectives[dir]; ok {
+		panic("directive " + dir + " already registered")
+	}
+	registeredDirectives[dir] = setupFunc
+}
+
+// RegisterHandlerDirective is like RegisterDirective, but for
+// directives which specifically output only an HTTP handler.
+func RegisterHandlerDirective(dir string, setupFunc UnmarshalHandlerFunc) {
+	RegisterDirective(dir, func(h Helper) ([]ConfigValue, error) {
+		if !h.Next() {
+			return nil, h.ArgErr()
+		}
+
+		matcherSet, ok, err := h.MatcherToken()
+		if err != nil {
+			return nil, err
+		}
+		if ok {
+			h.Dispenser.Delete() // strip matcher token
+		}
+
+		h.Dispenser.Reset() // pretend this lookahead never happened
+		val, err := setupFunc(h)
+		if err != nil {
+			return nil, err
+		}
+
+		return h.NewRoute(matcherSet, val), nil
+	})
+}
+
+// Helper is a type which helps setup a value from
+// Caddyfile tokens.
+type Helper struct {
+	*caddyfile.Dispenser
+	warnings    *[]caddyconfig.Warning
+	matcherDefs map[string]map[string]json.RawMessage
+}
+
+// JSON converts val into JSON. Any errors are added to warnings.
+func (h Helper) JSON(val interface{}, warnings *[]caddyconfig.Warning) json.RawMessage {
+	return caddyconfig.JSON(val, h.warnings)
+}
+
+// MatcherToken assumes the current token is (possibly) a matcher, and
+// if so, returns the matcher set along with a true value. If the current
+// token is not a matcher, nil and false is returned. Note that a true
+// value may be returned with a nil matcher set if it is a catch-all.
+func (h Helper) MatcherToken() (map[string]json.RawMessage, bool, error) {
+	if !h.NextArg() {
+		return nil, false, nil
+	}
+	return matcherSetFromMatcherToken(h.Dispenser.Token(), h.matcherDefs, h.warnings)
+}
+
+// NewRoute returns config values relevant to creating a new HTTP route.
+func (h Helper) NewRoute(matcherSet map[string]json.RawMessage,
+	handler caddyhttp.MiddlewareHandler) []ConfigValue {
+	mod, err := caddy.GetModule(caddy.GetModuleName(handler))
+	if err != nil {
+		// TODO: append to warnings
+	}
+	var matcherSetsRaw []map[string]json.RawMessage
+	if matcherSet != nil {
+		matcherSetsRaw = append(matcherSetsRaw, matcherSet)
+	}
+	return []ConfigValue{
+		{
+			Class: "route",
+			Value: caddyhttp.Route{
+				MatcherSetsRaw: matcherSetsRaw,
+				HandlersRaw:    []json.RawMessage{caddyconfig.JSONModuleObject(handler, "handler", mod.ID(), h.warnings)},
+			},
+		},
+	}
+}
+
+// NewBindAddresses returns config values relevant to adding
+// listener bind addresses to the config.
+func (h Helper) NewBindAddresses(addrs []string) []ConfigValue {
+	return []ConfigValue{{Class: "bind", Value: addrs}}
+}
+
+// NewVarsRoute returns config values relevant to adding a
+// "vars" wrapper route to the config.
+func (h Helper) NewVarsRoute(route caddyhttp.Route) []ConfigValue {
+	return []ConfigValue{{Class: "var", Value: route}}
+}
+
+// ConfigValue represents a value to be added to the final
+// configuration, or a value to be consulted when building
+// the final configuration.
+type ConfigValue struct {
+	// The kind of value this is. As the config is
+	// being built, the adapter will look in the
+	// "pile" for values belonging to a certain
+	// class when it is setting up a certain part
+	// of the config. The associated value will be
+	// type-asserted and placed accordingly.
+	Class string
+
+	// The value to be used when building the config.
+	// Generally its type is associated with the
+	// name of the Class.
+	Value interface{}
+
+	directive string
+}
+
+// serverBlock pairs a Caddyfile server block
+// with a "pile" of config values, keyed by class
+// name.
+type serverBlock struct {
+	block caddyfile.ServerBlock
+	pile  map[string][]ConfigValue // config values obtained from directives
+}
+
+type (
+	// UnmarshalFunc is a function which can unmarshal Caddyfile
+	// tokens into zero or more config values using a Helper type.
+	// These are passed in a call to RegisterDirective.
+	UnmarshalFunc func(h Helper) ([]ConfigValue, error)
+
+	// UnmarshalHandlerFunc is like UnmarshalFunc, except the
+	// output of the unmarshaling is an HTTP handler. This
+	// function does not need to deal with HTTP request matching
+	// which is abstracted away. Since writing HTTP handlers
+	// with Caddyfile support is very common, this is a more
+	// convenient way to add a handler to the chain since a lot
+	// of the details common to HTTP handlers are taken care of
+	// for you. These are passed to a call to
+	// RegisterHandlerDirective.
+	UnmarshalHandlerFunc func(h Helper) (caddyhttp.MiddlewareHandler, error)
+)
+
+var registeredDirectives = make(map[string]UnmarshalFunc)