TUN-528: Move cloudflared into a separate repo

vendor/github.com/mholt/caddy/caddyhttp/rewrite/rewrite.go

@@ -0,0 +1,263 @@
+// Copyright 2015 Light Code Labs, LLC
+//
+// 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 rewrite is middleware for rewriting requests internally to
+// a different path.
+package rewrite
+
+import (
+	"fmt"
+	"net/http"
+	"net/url"
+	"path"
+	"path/filepath"
+	"regexp"
+	"strings"
+
+	"github.com/mholt/caddy/caddyhttp/httpserver"
+)
+
+// Result is the result of a rewrite
+type Result int
+
+const (
+	// RewriteIgnored is returned when rewrite is not done on request.
+	RewriteIgnored Result = iota
+	// RewriteDone is returned when rewrite is done on request.
+	RewriteDone
+)
+
+// Rewrite is middleware to rewrite request locations internally before being handled.
+type Rewrite struct {
+	Next    httpserver.Handler
+	FileSys http.FileSystem
+	Rules   []httpserver.HandlerConfig
+}
+
+// ServeHTTP implements the httpserver.Handler interface.
+func (rw Rewrite) ServeHTTP(w http.ResponseWriter, r *http.Request) (int, error) {
+	if rule := httpserver.ConfigSelector(rw.Rules).Select(r); rule != nil {
+		rule.(Rule).Rewrite(rw.FileSys, r)
+	}
+
+	return rw.Next.ServeHTTP(w, r)
+}
+
+// Rule describes an internal location rewrite rule.
+type Rule interface {
+	httpserver.HandlerConfig
+	// Rewrite rewrites the internal location of the current request.
+	Rewrite(http.FileSystem, *http.Request) Result
+}
+
+// SimpleRule is a simple rewrite rule.
+type SimpleRule struct {
+	Regexp *regexp.Regexp
+	To     string
+	Negate bool
+}
+
+// NewSimpleRule creates a new Simple Rule
+func NewSimpleRule(from, to string, negate bool) (*SimpleRule, error) {
+	r, err := regexp.Compile(from)
+	if err != nil {
+		return nil, err
+	}
+	return &SimpleRule{
+		Regexp: r,
+		To:     to,
+		Negate: negate,
+	}, nil
+}
+
+// BasePath satisfies httpserver.Config
+func (s SimpleRule) BasePath() string { return "/" }
+
+// Match satisfies httpserver.Config
+func (s *SimpleRule) Match(r *http.Request) bool {
+	matches := regexpMatches(s.Regexp, "/", r.URL.Path)
+	if s.Negate {
+		return len(matches) == 0
+	}
+	return len(matches) > 0
+}
+
+// Rewrite rewrites the internal location of the current request.
+func (s *SimpleRule) Rewrite(fs http.FileSystem, r *http.Request) Result {
+
+	// attempt rewrite
+	return To(fs, r, s.To, newReplacer(r))
+}
+
+// ComplexRule is a rewrite rule based on a regular expression
+type ComplexRule struct {
+	// Path base. Request to this path and subpaths will be rewritten
+	Base string
+
+	// Path to rewrite to
+	To string
+
+	// Extensions to filter by
+	Exts []string
+
+	// Request matcher
+	httpserver.RequestMatcher
+
+	Regexp *regexp.Regexp
+}
+
+// NewComplexRule creates a new RegexpRule. It returns an error if regexp
+// pattern (pattern) or extensions (ext) are invalid.
+func NewComplexRule(base, pattern, to string, ext []string, matcher httpserver.RequestMatcher) (ComplexRule, error) {
+	// validate regexp if present
+	var r *regexp.Regexp
+	if pattern != "" {
+		var err error
+		r, err = regexp.Compile(pattern)
+		if err != nil {
+			return ComplexRule{}, err
+		}
+	}
+
+	// validate extensions if present
+	for _, v := range ext {
+		if len(v) < 2 || (len(v) < 3 && v[0] == '!') {
+			// check if no extension is specified
+			if v != "/" && v != "!/" {
+				return ComplexRule{}, fmt.Errorf("invalid extension %v", v)
+			}
+		}
+	}
+
+	// use both IfMatcher and PathMatcher
+	matcher = httpserver.MergeRequestMatchers(
+		// If condition matcher
+		matcher,
+		// Base path matcher
+		httpserver.PathMatcher(base),
+	)
+
+	return ComplexRule{
+		Base:           base,
+		To:             to,
+		Exts:           ext,
+		RequestMatcher: matcher,
+		Regexp:         r,
+	}, nil
+}
+
+// BasePath satisfies httpserver.Config
+func (r ComplexRule) BasePath() string { return r.Base }
+
+// Match satisfies httpserver.Config.
+//
+// Though ComplexRule embeds a RequestMatcher, additional
+// checks are needed which requires a custom implementation.
+func (r ComplexRule) Match(req *http.Request) bool {
+	// validate RequestMatcher
+	// includes if and path
+	if !r.RequestMatcher.Match(req) {
+		return false
+	}
+
+	// validate extensions
+	if !r.matchExt(req.URL.Path) {
+		return false
+	}
+
+	// if regex is nil, ignore
+	if r.Regexp == nil {
+		return true
+	}
+	// otherwise validate regex
+	return regexpMatches(r.Regexp, r.Base, req.URL.Path) != nil
+}
+
+// Rewrite rewrites the internal location of the current request.
+func (r ComplexRule) Rewrite(fs http.FileSystem, req *http.Request) (re Result) {
+	replacer := newReplacer(req)
+
+	// validate regexp if present
+	if r.Regexp != nil {
+		matches := regexpMatches(r.Regexp, r.Base, req.URL.Path)
+		switch len(matches) {
+		case 0:
+			// no match
+			return
+		default:
+			// set regexp match variables {1}, {2} ...
+
+			// url escaped values of ? and #.
+			q, f := url.QueryEscape("?"), url.QueryEscape("#")
+
+			for i := 1; i < len(matches); i++ {
+				// Special case of unescaped # and ? by stdlib regexp.
+				// Reverse the unescape.
+				if strings.ContainsAny(matches[i], "?#") {
+					matches[i] = strings.NewReplacer("?", q, "#", f).Replace(matches[i])
+				}
+
+				replacer.Set(fmt.Sprint(i), matches[i])
+			}
+		}
+	}
+
+	// attempt rewrite
+	return To(fs, req, r.To, replacer)
+}
+
+// matchExt matches rPath against registered file extensions.
+// Returns true if a match is found and false otherwise.
+func (r ComplexRule) matchExt(rPath string) bool {
+	f := filepath.Base(rPath)
+	ext := path.Ext(f)
+	if ext == "" {
+		ext = "/"
+	}
+
+	mustUse := false
+	for _, v := range r.Exts {
+		use := true
+		if v[0] == '!' {
+			use = false
+			v = v[1:]
+		}
+
+		if use {
+			mustUse = true
+		}
+
+		if ext == v {
+			return use
+		}
+	}
+
+	return !mustUse
+}
+
+func regexpMatches(regexp *regexp.Regexp, base, rPath string) []string {
+	if regexp != nil {
+		// include trailing slash in regexp if present
+		start := len(base)
+		if strings.HasSuffix(base, "/") {
+			start--
+		}
+		return regexp.FindStringSubmatch(rPath[start:])
+	}
+	return nil
+}
+
+func newReplacer(r *http.Request) httpserver.Replacer {
+	return httpserver.NewReplacer(r, nil, "")
+}