forked from caddyserver/caddy
/
rewrite.go
187 lines (155 loc) · 3.94 KB
/
rewrite.go
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// 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/middleware"
)
// Rewrite is middleware to rewrite request locations internally before being handled.
type Rewrite struct {
Next middleware.Handler
Rules []Rule
}
// ServeHTTP implements the middleware.Handler interface.
func (rw Rewrite) ServeHTTP(w http.ResponseWriter, r *http.Request) (int, error) {
for _, rule := range rw.Rules {
if ok := rule.Rewrite(r); ok {
break
}
}
return rw.Next.ServeHTTP(w, r)
}
// Rule describes an internal location rewrite rule.
type Rule interface {
// Rewrite rewrites the internal location of the current request.
Rewrite(*http.Request) bool
}
// SimpleRule is a simple rewrite rule.
type SimpleRule struct {
From, To string
}
// NewSimpleRule creates a new Simple Rule
func NewSimpleRule(from, to string) SimpleRule {
return SimpleRule{from, to}
}
// Rewrite rewrites the internal location of the current request.
func (s SimpleRule) Rewrite(r *http.Request) bool {
if s.From == r.URL.Path {
// take note of this rewrite for internal use by fastcgi
// all we need is the URI, not full URL
r.Header.Set(headerFieldName, r.URL.RequestURI())
// replace variables
to := path.Clean(middleware.NewReplacer(r, nil, "").Replace(s.To))
r.URL.Path = to
return true
}
return false
}
// RegexpRule is a rewrite rule based on a regular expression
type RegexpRule 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
*regexp.Regexp
}
// NewRegexpRule creates a new RegexpRule. It returns an error if regexp
// pattern (pattern) or extensions (ext) are invalid.
func NewRegexpRule(base, pattern, to string, ext []string) (*RegexpRule, error) {
r, err := regexp.Compile(pattern)
if err != nil {
return nil, err
}
// validate extensions
for _, v := range ext {
if len(v) < 2 || (len(v) < 3 && v[0] == '!') {
// check if no extension is specified
if v != "/" && v != "!/" {
return nil, fmt.Errorf("invalid extension %v", v)
}
}
}
return &RegexpRule{
base,
to,
ext,
r,
}, nil
}
// Rewrite rewrites the internal location of the current request.
func (r *RegexpRule) Rewrite(req *http.Request) bool {
rPath := req.URL.Path
// validate base
if !middleware.Path(rPath).Matches(r.Base) {
return false
}
// validate extensions
if !r.matchExt(rPath) {
return false
}
// include trailing slash in regexp if present
start := len(r.Base)
if strings.HasSuffix(r.Base, "/") {
start--
}
// validate regexp
if !r.MatchString(rPath[start:]) {
return false
}
// replace variables
to := path.Clean(middleware.NewReplacer(req, nil, "").Replace(r.To))
// validate resulting path
url, err := url.Parse(to)
if err != nil {
return false
}
// take note of this rewrite for internal use by fastcgi
// all we need is the URI, not full URL
req.Header.Set(headerFieldName, req.URL.RequestURI())
// perform rewrite
req.URL.Path = url.Path
if url.RawQuery != "" {
// overwrite query string if present
req.URL.RawQuery = url.RawQuery
}
return true
}
// matchExt matches rPath against registered file extensions.
// Returns true if a match is found and false otherwise.
func (r *RegexpRule) 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
}
}
if mustUse {
return false
}
return true
}
// When a rewrite is performed, this header is added to the request
// and is for internal use only, specifically the fastcgi middleware.
// It contains the original request URI before the rewrite.
const headerFieldName = "Caddy-Rewrite-Original-URI"