Allow proxy middleware to use query part in rewrite (fix #1798) (#1802)

middleware/middleware.go

@@ -2,7 +2,6 @@ package middleware
 
 import (
 	"net/http"
-	"net/url"
 	"regexp"
 	"strconv"
 	"strings"
@@ -49,30 +48,39 @@ func rewriteRulesRegex(rewrite map[string]string) map[*regexp.Regexp]string {
 	return rulesRegex
 }
 
-func rewritePath(rewriteRegex map[*regexp.Regexp]string, req *http.Request) {
-	for k, v := range rewriteRegex {
-		rawPath := req.URL.RawPath
-		if rawPath != "" {
-			// RawPath is only set when there has been escaping done. In that case Path must be deduced from rewritten RawPath
-			// because encoded Path could match rules that RawPath did not
-			if replacer := captureTokens(k, rawPath); replacer != nil {
-				rawPath = replacer.Replace(v)
+func rewriteURL(rewriteRegex map[*regexp.Regexp]string, req *http.Request) error {
+	if len(rewriteRegex) == 0 {
+		return nil
+	}
 
-				req.URL.RawPath = rawPath
-				req.URL.Path, _ = url.PathUnescape(rawPath)
-
-				return // rewrite only once
-			}
-
-			continue
+	// Depending how HTTP request is sent RequestURI could contain Scheme://Host/path or be just /path.
+	// We only want to use path part for rewriting and therefore trim prefix if it exists
+	rawURI := req.RequestURI
+	if rawURI != "" && rawURI[0] != '/' {
+		prefix := ""
+		if req.URL.Scheme != "" {
+			prefix = req.URL.Scheme + "://"
 		}
-
-		if replacer := captureTokens(k, req.URL.Path); replacer != nil {
-			req.URL.Path = replacer.Replace(v)
-
-			return // rewrite only once
+		if req.URL.Host != "" {
+			prefix += req.URL.Host // host or host:port
+		}
+		if prefix != "" {
+			rawURI = strings.TrimPrefix(rawURI, prefix)
 		}
 	}
+
+	for k, v := range rewriteRegex {
+		if replacer := captureTokens(k, rawURI); replacer != nil {
+			url, err := req.URL.Parse(replacer.Replace(v))
+			if err != nil {
+				return err
+			}
+			req.URL = url
+
+			return nil // rewrite only once
+		}
+	}
+	return nil
 }
 
 // DefaultSkipper returns false which processes the middleware.

middleware/middleware_test.go

@@ -8,11 +8,13 @@ import (
 	"testing"
 )
 
-func TestRewritePath(t *testing.T) {
+func TestRewriteURL(t *testing.T) {
 	var testCases = []struct {
 		whenURL       string
 		expectPath    string
 		expectRawPath string
+		expectQuery   string
+		expectErr     string
 	}{
 		{
 			whenURL:       "http://localhost:8080/old",
@@ -28,6 +30,7 @@ func TestRewritePath(t *testing.T) {
 			whenURL:       "http://localhost:8080/users/+_+/orders/___++++?test=1",
 			expectPath:    "/user/+_+/order/___++++",
 			expectRawPath: "",
+			expectQuery:   "test=1",
 		},
 		{
 			whenURL:       "http://localhost:8080/users/%20a/orders/%20aa",
@@ -35,9 +38,10 @@ func TestRewritePath(t *testing.T) {
 			expectRawPath: "",
 		},
 		{
-			whenURL:       "http://localhost:8080/%47%6f%2f",
+			whenURL:       "http://localhost:8080/%47%6f%2f?test=1",
 			expectPath:    "/Go/",
 			expectRawPath: "/%47%6f%2f",
+			expectQuery:   "test=1",
 		},
 		{
 			whenURL:       "/users/jill/orders/T%2FcO4lW%2Ft%2FVp%2F",
@@ -49,21 +53,40 @@ func TestRewritePath(t *testing.T) {
 			expectPath:    "/user/jill/order/T/cO4lW/t/Vp/",
 			expectRawPath: "/user/jill/order/T%2FcO4lW%2Ft%2FVp%2F",
 		},
+		{
+			whenURL:       "http://localhost:8080/static",
+			expectPath:    "/static/path",
+			expectRawPath: "",
+			expectQuery:   "role=AUTHOR&limit=1000",
+		},
+		{
+			whenURL:       "/static",
+			expectPath:    "/static/path",
+			expectRawPath: "",
+			expectQuery:   "role=AUTHOR&limit=1000",
+		},
 	}
 
 	rules := map[*regexp.Regexp]string{
 		regexp.MustCompile("^/old$"):                      "/new",
 		regexp.MustCompile("^/users/(.*?)/orders/(.*?)$"): "/user/$1/order/$2",
+		regexp.MustCompile("^/static$"):                   "/static/path?role=AUTHOR&limit=1000",
 	}
 
 	for _, tc := range testCases {
 		t.Run(tc.whenURL, func(t *testing.T) {
 			req := httptest.NewRequest(http.MethodGet, tc.whenURL, nil)
 
-			rewritePath(rules, req)
+			err := rewriteURL(rules, req)
 
+			if tc.expectErr != "" {
+				assert.EqualError(t, err, tc.expectErr)
+			} else {
+				assert.NoError(t, err)
+			}
 			assert.Equal(t, tc.expectPath, req.URL.Path)       // Path field is stored in decoded form: /%47%6f%2f becomes /Go/.
 			assert.Equal(t, tc.expectRawPath, req.URL.RawPath) // RawPath, an optional field which only gets set if the default encoding is different from Path.
+			assert.Equal(t, tc.expectQuery, req.URL.RawQuery)
 		})
 	}
 }

middleware/proxy.go

@@ -231,8 +231,9 @@ func ProxyWithConfig(config ProxyConfig) echo.MiddlewareFunc {
 			tgt := config.Balancer.Next(c)
 			c.Set(config.ContextKey, tgt)
 
-			// Set rewrite path and raw path
-			rewritePath(config.RegexRewrite, req)
+			if err := rewriteURL(config.RegexRewrite, req); err != nil {
+				return err
+			}
 
 			// Fix header
 			// Basically it's not good practice to unconditionally pass incoming x-real-ip header to upstream.

middleware/proxy_test.go

@@ -245,12 +245,16 @@ func TestProxyRewrite(t *testing.T) {
 
 func TestProxyRewriteRegex(t *testing.T) {
 	// Setup
-	upstream := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {}))
+	receivedRequestURI := make(chan string, 1)
+	upstream := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		// RequestURI is the unmodified request-target of the Request-Line (RFC 7230, Section 3.1.1) as sent by the client to a server
+		// we need unmodified target to see if we are encoding/decoding the url in addition to rewrite/replace logic
+		// if original request had `%2F` we should not magically decode it to `/` as it would change what was requested
+		receivedRequestURI <- r.RequestURI
+	}))
 	defer upstream.Close()
-	url, _ := url.Parse(upstream.URL)
-	rrb := NewRoundRobinBalancer([]*ProxyTarget{{Name: "upstream", URL: url}})
-	req := httptest.NewRequest(http.MethodGet, "/", nil)
-	rec := httptest.NewRecorder()
+	tmpUrL, _ := url.Parse(upstream.URL)
+	rrb := NewRoundRobinBalancer([]*ProxyTarget{{Name: "upstream", URL: tmpUrL}})
 
 	// Rewrite
 	e := echo.New()
@@ -279,14 +283,21 @@ func TestProxyRewriteRegex(t *testing.T) {
 		{"/c/ignore1/test/this", http.StatusOK, "/v3/test/this"},
 		{"/x/ignore/test", http.StatusOK, "/v4/test"},
 		{"/y/foo/bar", http.StatusOK, "/v5/bar/foo"},
+		// NB: fragment is not added by golang httputil.NewSingleHostReverseProxy implementation
+		// $2 = `bar?q=1#frag`, $1 = `foo`. replaced uri = `/v5/bar?q=1#frag/foo` but httputil.NewSingleHostReverseProxy does not send `#frag/foo` (currently)
+		{"/y/foo/bar?q=1#frag", http.StatusOK, "/v5/bar?q=1"},
 	}
 
 	for _, tc := range testCases {
 		t.Run(tc.requestPath, func(t *testing.T) {
-			req.URL, _ = url.Parse(tc.requestPath)
-			rec = httptest.NewRecorder()
+			targetURL, _ := url.Parse(tc.requestPath)
+			req := httptest.NewRequest(http.MethodGet, targetURL.String(), nil)
+			rec := httptest.NewRecorder()
+
 			e.ServeHTTP(rec, req)
-			assert.Equal(t, tc.expectPath, req.URL.EscapedPath())
+
+			actualRequestURI := <-receivedRequestURI
+			assert.Equal(t, tc.expectPath, actualRequestURI)
 			assert.Equal(t, tc.statusCode, rec.Code)
 		})
 	}

middleware/rewrite.go

@@ -72,9 +72,9 @@ func RewriteWithConfig(config RewriteConfig) echo.MiddlewareFunc {
 				return next(c)
 			}
 
-			req := c.Request()
-			// Set rewrite path and raw path
-			rewritePath(config.RegexRules, req)
+			if err := rewriteURL(config.RegexRules, c.Request()); err != nil {
+				return err
+			}
 			return next(c)
 		}
 	}

middleware/rewrite_test.go

@@ -220,6 +220,8 @@ func TestEchoRewriteWithRegexRules(t *testing.T) {
 func TestEchoRewriteReplacementEscaping(t *testing.T) {
 	e := echo.New()
 
+	// NOTE: these are incorrect regexps as they do not factor in that URI we are replacing could contain ? (query) and # (fragment) parts
+	// so in reality they append query and fragment part as `$1` matches everything after that prefix
 	e.Pre(RewriteWithConfig(RewriteConfig{
 		Rules: map[string]string{
 			"^/a/*": "/$1?query=param",
@@ -228,6 +230,7 @@ func TestEchoRewriteReplacementEscaping(t *testing.T) {
 		RegexRules: map[*regexp.Regexp]string{
 			regexp.MustCompile("^/x/(.*)"): "/$1?query=param",
 			regexp.MustCompile("^/y/(.*)"): "/$1;part#one",
+			regexp.MustCompile("^/z/(.*)"): "/$1?test=1#escaped%20test",
 		},
 	}))
 
@@ -236,13 +239,15 @@ func TestEchoRewriteReplacementEscaping(t *testing.T) {
 
 	testCases := []struct {
 		requestPath string
-		expectPath  string
+		expect      string
 	}{
 		{"/unmatched", "/unmatched"},
 		{"/a/test", "/test?query=param"},
 		{"/b/foo/bar", "/foo/bar;part#one"},
 		{"/x/test", "/test?query=param"},
 		{"/y/foo/bar", "/foo/bar;part#one"},
+		{"/z/foo/b%20ar", "/foo/b%20ar?test=1#escaped%20test"},
+		{"/z/foo/b%20ar?nope=1#yes", "/foo/b%20ar?nope=1#yes?test=1%23escaped%20test"}, // example of appending
 	}
 
 	for _, tc := range testCases {
@@ -250,7 +255,7 @@ func TestEchoRewriteReplacementEscaping(t *testing.T) {
 			req = httptest.NewRequest(http.MethodGet, tc.requestPath, nil)
 			rec = httptest.NewRecorder()
 			e.ServeHTTP(rec, req)
-			assert.Equal(t, tc.expectPath, req.URL.Path)
+			assert.Equal(t, tc.expect, req.URL.String())
 		})
 	}
 }