taldir

regexp.go (10461B)

---

 // Copyright 2012 The Gorilla Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 package mux
 
 import (
 	"bytes"
 	"fmt"
 	"net/http"
 	"net/url"
 	"regexp"
 	"strconv"
 	"strings"
 )
 
 type routeRegexpOptions struct {
 	strictSlash    bool
 	useEncodedPath bool
 }
 
 type regexpType int
 
 const (
 	regexpTypePath regexpType = iota
 	regexpTypeHost
 	regexpTypePrefix
 	regexpTypeQuery
 )
 
 // newRouteRegexp parses a route template and returns a routeRegexp,
 // used to match a host, a path or a query string.
 //
 // It will extract named variables, assemble a regexp to be matched, create
 // a "reverse" template to build URLs and compile regexps to validate variable
 // values used in URL building.
 //
 // Previously we accepted only Python-like identifiers for variable
 // names ([a-zA-Z_][a-zA-Z0-9_]*), but currently the only restriction is that
 // name and pattern can't be empty, and names can't contain a colon.
 func newRouteRegexp(tpl string, typ regexpType, options routeRegexpOptions) (*routeRegexp, error) {
 	// Check if it is well-formed.
 	idxs, errBraces := braceIndices(tpl)
 	if errBraces != nil {
 		return nil, errBraces
 	}
 	// Backup the original.
 	template := tpl
 	// Now let's parse it.
 	defaultPattern := "[^/]+"
 	if typ == regexpTypeQuery {
 		defaultPattern = ".*"
 	} else if typ == regexpTypeHost {
 		defaultPattern = "[^.]+"
 	}
 	// Only match strict slash if not matching
 	if typ != regexpTypePath {
 		options.strictSlash = false
 	}
 	// Set a flag for strictSlash.
 	endSlash := false
 	if options.strictSlash && strings.HasSuffix(tpl, "/") {
 		tpl = tpl[:len(tpl)-1]
 		endSlash = true
 	}
 	varsN := make([]string, len(idxs)/2)
 	varsR := make([]*regexp.Regexp, len(idxs)/2)
 	pattern := bytes.NewBufferString("")
 	pattern.WriteByte('^')
 	reverse := bytes.NewBufferString("")
 	var end int
 	var err error
 	for i := 0; i < len(idxs); i += 2 {
 		// Set all values we are interested in.
 		raw := tpl[end:idxs[i]]
 		end = idxs[i+1]
 		parts := strings.SplitN(tpl[idxs[i]+1:end-1], ":", 2)
 		name := parts[0]
 		patt := defaultPattern
 		if len(parts) == 2 {
 			patt = parts[1]
 		}
 		// Name or pattern can't be empty.
 		if name == "" || patt == "" {
 			return nil, fmt.Errorf("mux: missing name or pattern in %q",
 				tpl[idxs[i]:end])
 		}
 		// Build the regexp pattern.
 		fmt.Fprintf(pattern, "%s(?P<%s>%s)", regexp.QuoteMeta(raw), varGroupName(i/2), patt)
 
 		// Build the reverse template.
 		fmt.Fprintf(reverse, "%s%%s", raw)
 
 		// Append variable name and compiled pattern.
 		varsN[i/2] = name
 		varsR[i/2], err = regexp.Compile(fmt.Sprintf("^%s$", patt))
 		if err != nil {
 			return nil, err
 		}
 	}
 	// Add the remaining.
 	raw := tpl[end:]
 	pattern.WriteString(regexp.QuoteMeta(raw))
 	if options.strictSlash {
 		pattern.WriteString("[/]?")
 	}
 	if typ == regexpTypeQuery {
 		// Add the default pattern if the query value is empty
 		if queryVal := strings.SplitN(template, "=", 2)[1]; queryVal == "" {
 			pattern.WriteString(defaultPattern)
 		}
 	}
 	if typ != regexpTypePrefix {
 		pattern.WriteByte('$')
 	}
 
 	var wildcardHostPort bool
 	if typ == regexpTypeHost {
 		if !strings.Contains(pattern.String(), ":") {
 			wildcardHostPort = true
 		}
 	}
 	reverse.WriteString(raw)
 	if endSlash {
 		reverse.WriteByte('/')
 	}
 	// Compile full regexp.
 	reg, errCompile := regexp.Compile(pattern.String())
 	if errCompile != nil {
 		return nil, errCompile
 	}
 
 	// Check for capturing groups which used to work in older versions
 	if reg.NumSubexp() != len(idxs)/2 {
 		panic(fmt.Sprintf("route %s contains capture groups in its regexp. ", template) +
 			"Only non-capturing groups are accepted: e.g. (?:pattern) instead of (pattern)")
 	}
 
 	// Done!
 	return &routeRegexp{
 		template:         template,
 		regexpType:       typ,
 		options:          options,
 		regexp:           reg,
 		reverse:          reverse.String(),
 		varsN:            varsN,
 		varsR:            varsR,
 		wildcardHostPort: wildcardHostPort,
 	}, nil
 }
 
 // routeRegexp stores a regexp to match a host or path and information to
 // collect and validate route variables.
 type routeRegexp struct {
 	// The unmodified template.
 	template string
 	// The type of match
 	regexpType regexpType
 	// Options for matching
 	options routeRegexpOptions
 	// Expanded regexp.
 	regexp *regexp.Regexp
 	// Reverse template.
 	reverse string
 	// Variable names.
 	varsN []string
 	// Variable regexps (validators).
 	varsR []*regexp.Regexp
 	// Wildcard host-port (no strict port match in hostname)
 	wildcardHostPort bool
 }
 
 // Match matches the regexp against the URL host or path.
 func (r *routeRegexp) Match(req *http.Request, match *RouteMatch) bool {
 	if r.regexpType == regexpTypeHost {
 		host := getHost(req)
 		if r.wildcardHostPort {
 			// Don't be strict on the port match
 			if i := strings.Index(host, ":"); i != -1 {
 				host = host[:i]
 			}
 		}
 		return r.regexp.MatchString(host)
 	}
 
 	if r.regexpType == regexpTypeQuery {
 		return r.matchQueryString(req)
 	}
 	path := req.URL.Path
 	if r.options.useEncodedPath {
 		path = req.URL.EscapedPath()
 	}
 	return r.regexp.MatchString(path)
 }
 
 // url builds a URL part using the given values.
 func (r *routeRegexp) url(values map[string]string) (string, error) {
 	urlValues := make([]interface{}, len(r.varsN))
 	for k, v := range r.varsN {
 		value, ok := values[v]
 		if !ok {
 			return "", fmt.Errorf("mux: missing route variable %q", v)
 		}
 		if r.regexpType == regexpTypeQuery {
 			value = url.QueryEscape(value)
 		}
 		urlValues[k] = value
 	}
 	rv := fmt.Sprintf(r.reverse, urlValues...)
 	if !r.regexp.MatchString(rv) {
 		// The URL is checked against the full regexp, instead of checking
 		// individual variables. This is faster but to provide a good error
 		// message, we check individual regexps if the URL doesn't match.
 		for k, v := range r.varsN {
 			if !r.varsR[k].MatchString(values[v]) {
 				return "", fmt.Errorf(
 					"mux: variable %q doesn't match, expected %q", values[v],
 					r.varsR[k].String())
 			}
 		}
 	}
 	return rv, nil
 }
 
 // getURLQuery returns a single query parameter from a request URL.
 // For a URL with foo=bar&baz=ding, we return only the relevant key
 // value pair for the routeRegexp.
 func (r *routeRegexp) getURLQuery(req *http.Request) string {
 	if r.regexpType != regexpTypeQuery {
 		return ""
 	}
 	templateKey := strings.SplitN(r.template, "=", 2)[0]
 	val, ok := findFirstQueryKey(req.URL.RawQuery, templateKey)
 	if ok {
 		return templateKey + "=" + val
 	}
 	return ""
 }
 
 // findFirstQueryKey returns the same result as (*url.URL).Query()[key][0].
 // If key was not found, empty string and false is returned.
 func findFirstQueryKey(rawQuery, key string) (value string, ok bool) {
 	query := []byte(rawQuery)
 	for len(query) > 0 {
 		foundKey := query
 		if i := bytes.IndexAny(foundKey, "&;"); i >= 0 {
 			foundKey, query = foundKey[:i], foundKey[i+1:]
 		} else {
 			query = query[:0]
 		}
 		if len(foundKey) == 0 {
 			continue
 		}
 		var value []byte
 		if i := bytes.IndexByte(foundKey, '='); i >= 0 {
 			foundKey, value = foundKey[:i], foundKey[i+1:]
 		}
 		if len(foundKey) < len(key) {
 			// Cannot possibly be key.
 			continue
 		}
 		keyString, err := url.QueryUnescape(string(foundKey))
 		if err != nil {
 			continue
 		}
 		if keyString != key {
 			continue
 		}
 		valueString, err := url.QueryUnescape(string(value))
 		if err != nil {
 			continue
 		}
 		return valueString, true
 	}
 	return "", false
 }
 
 func (r *routeRegexp) matchQueryString(req *http.Request) bool {
 	return r.regexp.MatchString(r.getURLQuery(req))
 }
 
 // braceIndices returns the first level curly brace indices from a string.
 // It returns an error in case of unbalanced braces.
 func braceIndices(s string) ([]int, error) {
 	var level, idx int
 	var idxs []int
 	for i := 0; i < len(s); i++ {
 		switch s[i] {
 		case '{':
 			if level++; level == 1 {
 				idx = i
 			}
 		case '}':
 			if level--; level == 0 {
 				idxs = append(idxs, idx, i+1)
 			} else if level < 0 {
 				return nil, fmt.Errorf("mux: unbalanced braces in %q", s)
 			}
 		}
 	}
 	if level != 0 {
 		return nil, fmt.Errorf("mux: unbalanced braces in %q", s)
 	}
 	return idxs, nil
 }
 
 // varGroupName builds a capturing group name for the indexed variable.
 func varGroupName(idx int) string {
 	return "v" + strconv.Itoa(idx)
 }
 
 // ----------------------------------------------------------------------------
 // routeRegexpGroup
 // ----------------------------------------------------------------------------
 
 // routeRegexpGroup groups the route matchers that carry variables.
 type routeRegexpGroup struct {
 	host    *routeRegexp
 	path    *routeRegexp
 	queries []*routeRegexp
 }
 
 // setMatch extracts the variables from the URL once a route matches.
 func (v routeRegexpGroup) setMatch(req *http.Request, m *RouteMatch, r *Route) {
 	// Store host variables.
 	if v.host != nil {
 		host := getHost(req)
 		if v.host.wildcardHostPort {
 			// Don't be strict on the port match
 			if i := strings.Index(host, ":"); i != -1 {
 				host = host[:i]
 			}
 		}
 		matches := v.host.regexp.FindStringSubmatchIndex(host)
 		if len(matches) > 0 {
 			extractVars(host, matches, v.host.varsN, m.Vars)
 		}
 	}
 	path := req.URL.Path
 	if r.useEncodedPath {
 		path = req.URL.EscapedPath()
 	}
 	// Store path variables.
 	if v.path != nil {
 		matches := v.path.regexp.FindStringSubmatchIndex(path)
 		if len(matches) > 0 {
 			extractVars(path, matches, v.path.varsN, m.Vars)
 			// Check if we should redirect.
 			if v.path.options.strictSlash {
 				p1 := strings.HasSuffix(path, "/")
 				p2 := strings.HasSuffix(v.path.template, "/")
 				if p1 != p2 {
 					u, _ := url.Parse(req.URL.String())
 					if p1 {
 						u.Path = u.Path[:len(u.Path)-1]
 					} else {
 						u.Path += "/"
 					}
 					m.Handler = http.RedirectHandler(u.String(), http.StatusMovedPermanently)
 				}
 			}
 		}
 	}
 	// Store query string variables.
 	for _, q := range v.queries {
 		queryURL := q.getURLQuery(req)
 		matches := q.regexp.FindStringSubmatchIndex(queryURL)
 		if len(matches) > 0 {
 			extractVars(queryURL, matches, q.varsN, m.Vars)
 		}
 	}
 }
 
 // getHost tries its best to return the request host.
 // According to section 14.23 of RFC 2616 the Host header
 // can include the port number if the default value of 80 is not used.
 func getHost(r *http.Request) string {
 	if r.URL.IsAbs() {
 		return r.URL.Host
 	}
 	return r.Host
 }
 
 func extractVars(input string, matches []int, names []string, output map[string]string) {
 	for i, name := range names {
 		output[name] = input[matches[2*i+2]:matches[2*i+3]]
 	}
 }