directives.go

// 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"
	"net"
	"sort"
	"strconv"
	"strings"

	"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"
)

// directiveOrder specifies the order
// to apply directives in HTTP routes.
//
// The root directive goes first in case rewrites or
// redirects depend on existence of files, i.e. the
// file matcher, which must know the root first.
//
// The header directive goes second so that headers
// can be manipulated before doing redirects.
var directiveOrder = []string{
	"map",
	"root",

	"header",
	"request_body",

	"redir",
	"rewrite",

	// URI manipulation
	"uri",
	"try_files",

	// middleware handlers; some wrap responses
	"basicauth",
	"request_header",
	"encode",
	"templates",

	// special routing & dispatching directives
	"handle",
	"handle_path",
	"route",
	"push",

	// handlers that typically respond to requests
	"respond",
	"metrics",
	"reverse_proxy",
	"php_fastcgi",
	"file_server",
	"acme_server",
}

// directiveIsOrdered returns true if dir is
// a known, ordered (sorted) directive.
func directiveIsOrdered(dir string) bool {
	for _, d := range directiveOrder {
		if d == dir {
			return true
		}
	}
	return false
}

// 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.
// Directives registered with this function will always have
// an optional matcher token as the first argument.
func RegisterHandlerDirective(dir string, setupFunc UnmarshalHandlerFunc) {
	RegisterDirective(dir, func(h Helper) ([]ConfigValue, error) {
		if !h.Next() {
			return nil, h.ArgErr()
		}

		matcherSet, err := h.ExtractMatcherSet()
		if err != nil {
			return nil, err
		}

		val, err := setupFunc(h)
		if err != nil {
			return nil, err
		}

		return h.NewRoute(matcherSet, val), nil
	})
}

// RegisterGlobalOption registers a unique global option opt with
// an associated unmarshaling (setup) function. When the global
// option opt is encountered in a Caddyfile, setupFunc will be
// called to unmarshal its tokens.
func RegisterGlobalOption(opt string, setupFunc UnmarshalGlobalFunc) {
	if _, ok := registeredGlobalOptions[opt]; ok {
		panic("global option " + opt + " already registered")
	}
	registeredGlobalOptions[opt] = setupFunc
}

// Helper is a type which helps setup a value from
// Caddyfile tokens.
type Helper struct {
	*caddyfile.Dispenser
	// State stores intermediate variables during caddyfile adaptation.
	State        map[string]interface{}
	options      map[string]interface{}
	warnings     *[]caddyconfig.Warning
	matcherDefs  map[string]caddy.ModuleMap
	parentBlock  caddyfile.ServerBlock
	groupCounter counter
}

// Option gets the option keyed by name.
func (h Helper) Option(name string) interface{} {
	return h.options[name]
}

// Caddyfiles returns the list of config files from
// which tokens in the current server block were loaded.
func (h Helper) Caddyfiles() []string {
	// first obtain set of names of files involved
	// in this server block, without duplicates
	files := make(map[string]struct{})
	for _, segment := range h.parentBlock.Segments {
		for _, token := range segment {
			files[token.File] = struct{}{}
		}
	}
	// then convert the set into a slice
	filesSlice := make([]string, 0, len(files))
	for file := range files {
		filesSlice = append(filesSlice, file)
	}
	return filesSlice
}

// JSON converts val into JSON. Any errors are added to warnings.
func (h Helper) JSON(val interface{}) json.RawMessage {
	return caddyconfig.JSON(val, h.warnings)
}

// MatcherToken assumes the next argument token is (possibly) a matcher,
// and if so, returns the matcher set along with a true value. If the next
// 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() (caddy.ModuleMap, bool, error) {
	if !h.NextArg() {
		return nil, false, nil
	}
	return matcherSetFromMatcherToken(h.Dispenser.Token(), h.matcherDefs, h.warnings)
}

// ExtractMatcherSet is like MatcherToken, except this is a higher-level
// method that returns the matcher set described by the matcher token,
// or nil if there is none, and deletes the matcher token from the
// dispenser and resets it as if this look-ahead never happened. Useful
// when wrapping a route (one or more handlers) in a user-defined matcher.
func (h Helper) ExtractMatcherSet() (caddy.ModuleMap, error) {
	matcherSet, hasMatcher, err := h.MatcherToken()
	if err != nil {
		return nil, err
	}
	if hasMatcher {
		// strip matcher token; we don't need to
		// use the return value here because a
		// new dispenser should have been made
		// solely for this directive's tokens,
		// with no other uses of same slice
		h.Dispenser.Delete()
	}
	h.Dispenser.Reset() // pretend this lookahead never happened
	return matcherSet, nil
}

// NewRoute returns config values relevant to creating a new HTTP route.
func (h Helper) NewRoute(matcherSet caddy.ModuleMap,
	handler caddyhttp.MiddlewareHandler) []ConfigValue {
	mod, err := caddy.GetModule(caddy.GetModuleID(handler))
	if err != nil {
		*h.warnings = append(*h.warnings, caddyconfig.Warning{
			File:    h.File(),
			Line:    h.Line(),
			Message: err.Error(),
		})
		return nil
	}
	var matcherSetsRaw []caddy.ModuleMap
	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.Name(), h.warnings)},
			},
		},
	}
}

// GroupRoutes adds the routes (caddyhttp.Route type) in vals to the
// same group, if there is more than one route in vals.
func (h Helper) GroupRoutes(vals []ConfigValue) {
	// ensure there's at least two routes; group of one is pointless
	var count int
	for _, v := range vals {
		if _, ok := v.Value.(caddyhttp.Route); ok {
			count++
			if count > 1 {
				break
			}
		}
	}
	if count < 2 {
		return
	}

	// now that we know the group will have some effect, do it
	groupName := h.groupCounter.nextGroup()
	for i := range vals {
		if route, ok := vals[i].Value.(caddyhttp.Route); ok {
			route.Group = groupName
			vals[i].Value = route
		}
	}
}

// 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}}
}

// ParseSegmentAsSubroute parses the segment such that its subdirectives
// are themselves treated as directives, from which a subroute is built
// and returned.
func ParseSegmentAsSubroute(h Helper) (caddyhttp.MiddlewareHandler, error) {
	allResults, err := parseSegmentAsConfig(h)
	if err != nil {
		return nil, err
	}

	return buildSubroute(allResults, h.groupCounter)
}

// parseSegmentAsConfig parses the segment such that its subdirectives
// are themselves treated as directives, including named matcher definitions,
// and the raw Config structs are returned.
func parseSegmentAsConfig(h Helper) ([]ConfigValue, error) {
	var allResults []ConfigValue

	for h.Next() {
		// don't allow non-matcher args on the first line
		if h.NextArg() {
			return nil, h.ArgErr()
		}

		// slice the linear list of tokens into top-level segments
		var segments []caddyfile.Segment
		for nesting := h.Nesting(); h.NextBlock(nesting); {
			segments = append(segments, h.NextSegment())
		}

		// copy existing matcher definitions so we can augment
		// new ones that are defined only in this scope
		matcherDefs := make(map[string]caddy.ModuleMap, len(h.matcherDefs))
		for key, val := range h.matcherDefs {
			matcherDefs[key] = val
		}

		// find and extract any embedded matcher definitions in this scope
		for i := 0; i < len(segments); i++ {
			seg := segments[i]
			if strings.HasPrefix(seg.Directive(), matcherPrefix) {
				// parse, then add the matcher to matcherDefs
				err := parseMatcherDefinitions(caddyfile.NewDispenser(seg), matcherDefs)
				if err != nil {
					return nil, err
				}
				// remove the matcher segment (consumed), then step back the loop
				segments = append(segments[:i], segments[i+1:]...)
				i--
			}
		}

		// with matchers ready to go, evaluate each directive's segment
		for _, seg := range segments {
			dir := seg.Directive()
			dirFunc, ok := registeredDirectives[dir]
			if !ok {
				return nil, h.Errf("unrecognized directive: %s", dir)
			}

			subHelper := h
			subHelper.Dispenser = caddyfile.NewDispenser(seg)
			subHelper.matcherDefs = matcherDefs

			results, err := dirFunc(subHelper)
			if err != nil {
				return nil, h.Errf("parsing caddyfile tokens for '%s': %v", dir, err)
			}
			for _, result := range results {
				result.directive = dir
				allResults = append(allResults, result)
			}
		}
	}

	return allResults, nil
}

// 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
}

func sortRoutes(routes []ConfigValue) {
	dirPositions := make(map[string]int)
	for i, dir := range directiveOrder {
		dirPositions[dir] = i
	}

	sort.SliceStable(routes, func(i, j int) bool {
		// if the directives are different, just use the established directive order
		iDir, jDir := routes[i].directive, routes[j].directive
		if iDir != jDir {
			return dirPositions[iDir] < dirPositions[jDir]
		}

		// directives are the same; sub-sort by path matcher length if there's
		// only one matcher set and one path (this is a very common case and
		// usually -- but not always -- helpful/expected, oh well; user can
		// always take manual control of order using handler or route blocks)
		iRoute, ok := routes[i].Value.(caddyhttp.Route)
		if !ok {
			return false
		}
		jRoute, ok := routes[j].Value.(caddyhttp.Route)
		if !ok {
			return false
		}

		// decode the path matchers, if there is just one of them
		var iPM, jPM caddyhttp.MatchPath
		if len(iRoute.MatcherSetsRaw) == 1 {
			_ = json.Unmarshal(iRoute.MatcherSetsRaw[0]["path"], &iPM)
		}
		if len(jRoute.MatcherSetsRaw) == 1 {
			_ = json.Unmarshal(jRoute.MatcherSetsRaw[0]["path"], &jPM)
		}

		// sort by longer path (more specific) first; missing path
		// matchers or multi-matchers are treated as zero-length paths
		var iPathLen, jPathLen int
		if len(iPM) > 0 {
			iPathLen = len(iPM[0])
		}
		if len(jPM) > 0 {
			jPathLen = len(jPM[0])
		}

		// if both directives have no path matcher, use whichever one
		// has any kind of matcher defined first.
		if iPathLen == 0 && jPathLen == 0 {
			return len(iRoute.MatcherSetsRaw) > 0 && len(jRoute.MatcherSetsRaw) == 0
		}

		// sort with the most-specific (longest) path first
		return iPathLen > jPathLen
	})
}

// serverBlock pairs a Caddyfile server block with
// a "pile" of config values, keyed by class name,
// as well as its parsed keys for convenience.
type serverBlock struct {
	block caddyfile.ServerBlock
	pile  map[string][]ConfigValue // config values obtained from directives
	keys  []Address
}

// hostsFromKeys returns a list of all the non-empty hostnames found in
// the keys of the server block sb. If logger mode is false, a key with
// an empty hostname portion will return an empty slice, since that
// server block is interpreted to effectively match all hosts. An empty
// string is never added to the slice.
//
// If loggerMode is true, then the non-standard ports of keys will be
// joined to the hostnames. This is to effectively match the Host
// header of requests that come in for that key.
//
// The resulting slice is not sorted but will never have duplicates.
func (sb serverBlock) hostsFromKeys(loggerMode bool) []string {
	// ensure each entry in our list is unique
	hostMap := make(map[string]struct{})
	for _, addr := range sb.keys {
		if addr.Host == "" {
			if !loggerMode {
				// server block contains a key like ":443", i.e. the host portion
				// is empty / catch-all, which means to match all hosts
				return []string{}
			}
			// never append an empty string
			continue
		}
		if loggerMode &&
			addr.Port != "" &&
			addr.Port != strconv.Itoa(caddyhttp.DefaultHTTPPort) &&
			addr.Port != strconv.Itoa(caddyhttp.DefaultHTTPSPort) {
			hostMap[net.JoinHostPort(addr.Host, addr.Port)] = struct{}{}
		} else {
			hostMap[addr.Host] = struct{}{}
		}
	}

	// convert map to slice
	sblockHosts := make([]string, 0, len(hostMap))
	for host := range hostMap {
		sblockHosts = append(sblockHosts, host)
	}

	return sblockHosts
}

// hasHostCatchAllKey returns true if sb has a key that
// omits a host portion, i.e. it "catches all" hosts.
func (sb serverBlock) hasHostCatchAllKey() bool {
	for _, addr := range sb.keys {
		if addr.Host == "" {
			return true
		}
	}
	return false
}

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)

	// UnmarshalGlobalFunc is a function which can unmarshal Caddyfile
	// tokens into a global option config value using a Helper type.
	// These are passed in a call to RegisterGlobalOption.
	UnmarshalGlobalFunc func(d *caddyfile.Dispenser) (interface{}, error)
)

var registeredDirectives = make(map[string]UnmarshalFunc)

var registeredGlobalOptions = make(map[string]UnmarshalGlobalFunc)