Rewrite: added regexp. awaiting documentation and tests.

config/setup/rewrite.go

@@ -19,22 +19,60 @@ func Rewrite(c *Controller) (middleware.Middleware, error) {
 
 func rewriteParse(c *Controller) ([]rewrite.Rule, error) {
 	var rewrites []rewrite.Rule
+	var regexps []rewrite.Rule
 
 	for c.Next() {
 		var rule rewrite.Rule
+		var err error
 
-		if !c.NextArg() {
-			return rewrites, c.ArgErr()
-		}
-		rule.From = c.Val()
+		args := c.RemainingArgs()
+
+		switch len(args) {
+		case 2:
+			if args[0] != "regexp" {
+				rule = rewrite.NewSimpleRule(args[0], args[1])
+				rewrites = append(rewrites, rule)
+				continue
+			}
+
+			var base = args[1]
+			var pattern, to string
+			var ext []string
 
-		if !c.NextArg() {
+			for c.NextBlock() {
+				switch c.Val() {
+				case "pattern":
+					if !c.NextArg() {
+						return rewrites, c.ArgErr()
+					}
+					pattern = c.Val()
+				case "to":
+					if !c.NextArg() {
+						return rewrites, c.ArgErr()
+					}
+					to = c.Val()
+				case "ext":
+					args1 := c.RemainingArgs()
+					if len(args1) == 0 {
+						return rewrites, c.ArgErr()
+					}
+					ext = args1
+				default:
+					return rewrites, c.ArgErr()
+				}
+			}
+			if pattern == "" || to == "" {
+				return rewrites, c.ArgErr()
+			}
+			if rule, err = rewrite.NewRegexpRule(base, pattern, to, ext); err != nil {
+				return rewrites, err
+			}
+			rewrites = append(regexps, rule)
+		default:
 			return rewrites, c.ArgErr()
 		}
-		rule.To = c.Val()
 
-		rewrites = append(rewrites, rule)
 	}
 
-	return rewrites, nil
+	return append(rewrites, regexps...), nil
 }

middleware/rewrite/rewrite.go

@@ -5,7 +5,13 @@ package rewrite
 import (
 	"net/http"
 
+	"fmt"
 	"github.com/mholt/caddy/middleware"
+	"net/url"
+	"path"
+	"path/filepath"
+	"regexp"
+	"strings"
 )
 
 // Rewrite is middleware to rewrite request locations internally before being handled.
@@ -17,8 +23,7 @@ type Rewrite struct {
 // ServeHTTP implements the middleware.Handler interface.
 func (rw Rewrite) ServeHTTP(w http.ResponseWriter, r *http.Request) (int, error) {
 	for _, rule := range rw.Rules {
-		if r.URL.Path == rule.From {
-			r.URL.Path = rule.To
+		if ok := rule.Rewrite(r); ok {
 			break
 		}
 	}
@@ -26,6 +31,121 @@ func (rw Rewrite) ServeHTTP(w http.ResponseWriter, r *http.Request) (int, error)
 }
 
 // A Rule describes an internal location rewrite rule.
-type Rule struct {
-	From, To string
+type Rule interface {
+	Rewrite(*http.Request) bool
+}
+
+type SimpleRule [2]string
+
+func NewSimpleRule(from, to string) SimpleRule {
+	return SimpleRule{from, to}
+}
+
+func (s SimpleRule) Rewrite(r *http.Request) bool {
+	if s[0] == r.URL.Path {
+		r.URL.Path = s[1]
+		return true
+	}
+	return false
+}
+
+type RegexpRule struct {
+	base, to string
+	ext      []string
+	*regexp.Regexp
+}
+
+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 it is no extension
+			if v != "/" && v != "!/" {
+				return nil, fmt.Errorf("Invalid extension %v", v)
+			}
+		}
+	}
+
+	return &RegexpRule{
+		base,
+		to,
+		ext,
+		r,
+	}, nil
+}
+
+var regexpVars [2]string = [2]string{
+	"$path",
+	"$query",
+}
+
+func (r *RegexpRule) Rewrite(req *http.Request) bool {
+	rPath := req.URL.Path
+	if strings.Index(rPath, r.base) != 0 {
+		return false
+	}
+	if !r.matchExt(rPath) {
+		return false
+	}
+	if !r.MatchString(req.URL.Path) {
+		return false
+	}
+
+	to := r.to
+
+	// check variables
+	for _, v := range regexpVars {
+		if strings.Contains(r.to, v) {
+			switch v {
+			case regexpVars[0]:
+				to = strings.Replace(to, v, req.URL.Path[1:], -1)
+			case regexpVars[1]:
+				to = strings.Replace(to, v, req.URL.RawQuery, -1)
+			}
+		}
+	}
+
+	url, err := url.Parse(to)
+	if err != nil {
+		return false
+	}
+
+	req.URL.Path = url.Path
+	req.URL.RawQuery = url.RawQuery
+
+	return true
+}
+
+func (r *RegexpRule) matchExt(rPath string) bool {
+	f := filepath.Base(rPath)
+	ext := path.Ext(f)
+	if ext == "" {
+		ext = "/"
+	}
+	mustUse := false
+	for _, v := range r.ext {
+		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
 }