docs: cleanup comments

See #211 and #215

.github/workflows/lint.yml

@@ -18,4 +18,4 @@ jobs:
           go-version: "1.23.x"
       - uses: golangci/golangci-lint-action@v6
         with:
-          version: "v1.60"
+          version: "v1.62"

README.md

@@ -49,6 +49,12 @@ docker run \
   ghcr.io/hacdias/webdav -c /config.yml
 ```
 
+If you are using [fail2ban](#fail2ban-setup), it would be helpful to add the parameters listed below. They will assist in analyzing the log.
+```bash
+--log-driver journald \
+--name webdav \
+```
+
 ## Configuration
 
 The configuration can be provided as a YAML, JSON or TOML file. Below is an example of a YAML configuration file with all the options available, as well as what they mean.
@@ -139,6 +145,8 @@ users:
   - username: admin
     password: admin
   # Example 'john' user with bcrypt encrypted password, with custom directory.
+  # You can generate a bcrypt-encrypted password by using the 'webdav bcrypt'
+  # command lint utility.
   - username: john
     password: "{bcrypt}$2y$10$zEP6oofmXFeHaeMfBNLnP.DO8m.H.Mwhd24/TOX2MWLxAExXi4qgi"
     directory: /another/path
@@ -221,10 +229,8 @@ before = common.conf
 
 [Definition]
 # Failregex to match "invalid password" and extract remote_address only
-failregex = ^.*invalid password\s*\{.*"remote_address":\s*"<HOST>"\s*\}
-
-# Failregex to match "invalid username" and extract remote_address only (if applicable)
-failregex += ^.*invalid username\s*\{.*"remote_address":\s*"<HOST>"\s*\}
+failregex = ^.*invalid password\s*\{.*"remote_address":\s*"<HOST>:\d+"\s*\}
+            ^.*invalid username\s*\{.*"remote_address":\s*"<HOST>:\d+"\s*\}
 
 ignoreregex =
 ```
@@ -249,6 +255,8 @@ ignoreself = false
 - Replace `[your_port]` with the port your WebDAV server is running on.
 - Replace `[your_log_path]` with the path to your WebDAV log file.
 
+If you use it with Docker and `--log-driver journald`, replace `logpath` with `journalmatch = CONTAINER_NAME=[your_container_name]`
+
 #### Final Steps
 
 1. Restart Fail2Ban to apply these configurations:

cmd/bcrypt.go

@@ -0,0 +1,49 @@
+package cmd
+
+import (
+	"errors"
+	"fmt"
+
+	"github.com/spf13/cobra"
+	"golang.org/x/crypto/bcrypt"
+)
+
+func init() {
+	flags := bcryptCmd.Flags()
+	flags.IntP("cost", "c", bcrypt.DefaultCost, "cost used to generate password, higher cost leads to slower verification times")
+
+	rootCmd.AddCommand(bcryptCmd)
+}
+
+var bcryptCmd = &cobra.Command{
+	Use:   "bcrypt",
+	Short: "Generate a bcrypt encrypted password",
+	Args:  cobra.ExactArgs(1),
+	RunE: func(cmd *cobra.Command, args []string) error {
+		cost, err := cmd.Flags().GetInt("cost")
+		if err != nil {
+			return err
+		}
+
+		if cost < bcrypt.MinCost {
+			return fmt.Errorf("given cost cannot be under minimum cost of %d", bcrypt.MinCost)
+		}
+
+		if cost > bcrypt.MaxCost {
+			return fmt.Errorf("given cost cannot be over maximum cost of %d", bcrypt.MaxCost)
+		}
+
+		pwd := args[0]
+		if pwd == "" {
+			return errors.New("password argument must not be empty")
+		}
+
+		hash, err := bcrypt.GenerateFromPassword([]byte(pwd), cost)
+		if err != nil {
+			return err
+		}
+
+		fmt.Println(string(hash))
+		return nil
+	},
+}

go.mod

@@ -3,7 +3,7 @@ module github.com/hacdias/webdav/v5
 go 1.23
 
 require (
-	github.com/coreos/go-systemd/v22 v22.3.2
+	github.com/coreos/go-systemd/v22 v22.5.0
 	github.com/go-viper/mapstructure/v2 v2.2.1
 	github.com/rs/cors v1.11.1
 	github.com/spf13/cobra v1.8.1
@@ -12,8 +12,8 @@ require (
 	github.com/stretchr/testify v1.9.0
 	github.com/studio-b12/gowebdav v0.9.0
 	go.uber.org/zap v1.27.0
-	golang.org/x/crypto v0.29.0
-	golang.org/x/net v0.31.0
+	golang.org/x/crypto v0.31.0
+	golang.org/x/net v0.33.0
 )
 
 require (
@@ -21,7 +21,7 @@ require (
 	github.com/fsnotify/fsnotify v1.8.0 // indirect
 	github.com/hashicorp/hcl v1.0.0 // indirect
 	github.com/inconshreveable/mousetrap v1.1.0 // indirect
-	github.com/magiconair/properties v1.8.7 // indirect
+	github.com/magiconair/properties v1.8.9 // indirect
 	github.com/mitchellh/mapstructure v1.5.0 // indirect
 	github.com/pelletier/go-toml/v2 v2.2.3 // indirect
 	github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 // indirect
@@ -29,12 +29,12 @@ require (
 	github.com/sagikazarmark/slog-shim v0.1.0 // indirect
 	github.com/sourcegraph/conc v0.3.0 // indirect
 	github.com/spf13/afero v1.11.0 // indirect
-	github.com/spf13/cast v1.7.0 // indirect
+	github.com/spf13/cast v1.7.1 // indirect
 	github.com/subosito/gotenv v1.6.0 // indirect
 	go.uber.org/multierr v1.11.0 // indirect
-	golang.org/x/exp v0.0.0-20241108190413-2d47ceb2692f // indirect
-	golang.org/x/sys v0.27.0 // indirect
-	golang.org/x/text v0.20.0 // indirect
+	golang.org/x/exp v0.0.0-20241217172543-b2144cdd0a67 // indirect
+	golang.org/x/sys v0.28.0 // indirect
+	golang.org/x/text v0.21.0 // indirect
 	gopkg.in/ini.v1 v1.67.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )

go.sum

@@ -1,5 +1,5 @@
-github.com/coreos/go-systemd/v22 v22.3.2 h1:D9/bQk5vlXQFZ6Kwuu6zaiXJ9oTPe68++AzAJc1DzSI=
-github.com/coreos/go-systemd/v22 v22.3.2/go.mod h1:Y58oyj3AT4RCenI/lSvhwexgC+NSVTIJ3seZv2GcEnc=
+github.com/coreos/go-systemd/v22 v22.5.0 h1:RrqgGjYQKalulkV8NGVIfkXQf6YYmOyiJKk8iXXhfZs=
+github.com/coreos/go-systemd/v22 v22.5.0/go.mod h1:Y58oyj3AT4RCenI/lSvhwexgC+NSVTIJ3seZv2GcEnc=
 github.com/cpuguy83/go-md2man/v2 v2.0.4/go.mod h1:tgQtvFlXSQOSOSIRvRPT7W67SCa46tRHOmNcaadrF8o=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc h1:U9qPSI2PIWSS1VwoXQT9A3Wy9MM3WgvqSxFWenqJduM=
@@ -21,8 +21,8 @@ github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
 github.com/kr/pretty v0.3.1/go.mod h1:hoEshYVHaxMs3cyo3Yncou5ZscifuDolrwPKZanG3xk=
 github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
 github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
-github.com/magiconair/properties v1.8.7 h1:IeQXZAiQcpL9mgcAe1Nu6cX9LLw6ExEHKjN0VQdvPDY=
-github.com/magiconair/properties v1.8.7/go.mod h1:Dhd985XPs7jluiymwWYZ0G4Z61jb3vdS329zhj2hYo0=
+github.com/magiconair/properties v1.8.9 h1:nWcCbLq1N2v/cpNsy5WvQ37Fb+YElfq20WJ/a8RkpQM=
+github.com/magiconair/properties v1.8.9/go.mod h1:Dhd985XPs7jluiymwWYZ0G4Z61jb3vdS329zhj2hYo0=
 github.com/mitchellh/mapstructure v1.5.0 h1:jeMsZIYE/09sWLaz43PL7Gy6RuMjD2eJVyuac5Z2hdY=
 github.com/mitchellh/mapstructure v1.5.0/go.mod h1:bFUtVrKA4DC2yAKiSyO/QUcy7e+RRV2QTWOzhPopBRo=
 github.com/pelletier/go-toml/v2 v2.2.3 h1:YmeHyLY8mFWbdkNWwpr+qIL2bEqT0o95WSdkNHvL12M=
@@ -42,8 +42,8 @@ github.com/sourcegraph/conc v0.3.0 h1:OQTbbt6P72L20UqAkXXuLOj79LfEanQ+YQFNpLA9yS
 github.com/sourcegraph/conc v0.3.0/go.mod h1:Sdozi7LEKbFPqYX2/J+iBAM6HpqSLTASQIKqDmF7Mt0=
 github.com/spf13/afero v1.11.0 h1:WJQKhtpdm3v2IzqG8VMqrr6Rf3UYpEF239Jy9wNepM8=
 github.com/spf13/afero v1.11.0/go.mod h1:GH9Y3pIexgf1MTIWtNGyogA5MwRIDXGUr+hbWNoBjkY=
-github.com/spf13/cast v1.7.0 h1:ntdiHjuueXFgm5nzDRdOS4yfT43P5Fnud6DH50rz/7w=
-github.com/spf13/cast v1.7.0/go.mod h1:ancEpBxwJDODSW/UG4rDrAqiKolqNNh2DX3mk86cAdo=
+github.com/spf13/cast v1.7.1 h1:cuNEagBQEHWN1FnbGEjCXL2szYEXqfJPbP2HNUaca9Y=
+github.com/spf13/cast v1.7.1/go.mod h1:ancEpBxwJDODSW/UG4rDrAqiKolqNNh2DX3mk86cAdo=
 github.com/spf13/cobra v1.8.1 h1:e5/vxKd/rZsfSJMUX1agtjeTDf+qv1/JdBF8gg5k9ZM=
 github.com/spf13/cobra v1.8.1/go.mod h1:wHxEcudfqmLYa8iTfL+OuZPbBZkmvliBWKIezN3kD9Y=
 github.com/spf13/pflag v1.0.5 h1:iy+VFUOCP1a+8yFto/drg2CJ5u0yRoB7fZw3DKv/JXA=
@@ -62,16 +62,16 @@ go.uber.org/multierr v1.11.0 h1:blXXJkSxSSfBVBlC76pxqeO+LN3aDfLQo+309xJstO0=
 go.uber.org/multierr v1.11.0/go.mod h1:20+QtiLqy0Nd6FdQB9TLXag12DsQkrbs3htMFfDN80Y=
 go.uber.org/zap v1.27.0 h1:aJMhYGrd5QSmlpLMr2MftRKl7t8J8PTZPA732ud/XR8=
 go.uber.org/zap v1.27.0/go.mod h1:GB2qFLM7cTU87MWRP2mPIjqfIDnGu+VIO4V/SdhGo2E=
-golang.org/x/crypto v0.29.0 h1:L5SG1JTTXupVV3n6sUqMTeWbjAyfPwoda2DLX8J8FrQ=
-golang.org/x/crypto v0.29.0/go.mod h1:+F4F4N5hv6v38hfeYwTdx20oUvLLc+QfrE9Ax9HtgRg=
-golang.org/x/exp v0.0.0-20241108190413-2d47ceb2692f h1:XdNn9LlyWAhLVp6P/i8QYBW+hlyhrhei9uErw2B5GJo=
-golang.org/x/exp v0.0.0-20241108190413-2d47ceb2692f/go.mod h1:D5SMRVC3C2/4+F/DB1wZsLRnSNimn2Sp/NPsCrsv8ak=
-golang.org/x/net v0.31.0 h1:68CPQngjLL0r2AlUKiSxtQFKvzRVbnzLwMUn5SzcLHo=
-golang.org/x/net v0.31.0/go.mod h1:P4fl1q7dY2hnZFxEk4pPSkDHF+QqjitcnDjUQyMM+pM=
-golang.org/x/sys v0.27.0 h1:wBqf8DvsY9Y/2P8gAfPDEYNuS30J4lPHJxXSb/nJZ+s=
-golang.org/x/sys v0.27.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
-golang.org/x/text v0.20.0 h1:gK/Kv2otX8gz+wn7Rmb3vT96ZwuoxnQlY+HlJVj7Qug=
-golang.org/x/text v0.20.0/go.mod h1:D4IsuqiFMhST5bX19pQ9ikHC2GsaKyk/oF+pn3ducp4=
+golang.org/x/crypto v0.31.0 h1:ihbySMvVjLAeSH1IbfcRTkD/iNscyz8rGzjF/E5hV6U=
+golang.org/x/crypto v0.31.0/go.mod h1:kDsLvtWBEx7MV9tJOj9bnXsPbxwJQ6csT/x4KIN4Ssk=
+golang.org/x/exp v0.0.0-20241217172543-b2144cdd0a67 h1:1UoZQm6f0P/ZO0w1Ri+f+ifG/gXhegadRdwBIXEFWDo=
+golang.org/x/exp v0.0.0-20241217172543-b2144cdd0a67/go.mod h1:qj5a5QZpwLU2NLQudwIN5koi3beDhSAlJwa67PuM98c=
+golang.org/x/net v0.33.0 h1:74SYHlV8BIgHIFC/LrYkOGIwL19eTYXQ5wc6TBuO36I=
+golang.org/x/net v0.33.0/go.mod h1:HXLR5J+9DxmrqMwG9qjGCxZ+zKXxBru04zlTvWlWuN4=
+golang.org/x/sys v0.28.0 h1:Fksou7UEQUWlKvIdsqzJmUmCX3cZuD2+P3XyyzwMhlA=
+golang.org/x/sys v0.28.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+golang.org/x/text v0.21.0 h1:zyQAAkrwaneQ066sspRyJaG9VNi/YJ1NfzcGB3hZ/qo=
+golang.org/x/text v0.21.0/go.mod h1:4IBbMaMmOPCJ8SecivzSH54+73PCFmPWxNTLm+vZkEQ=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15 h1:YR8cESwS4TdDjEe65xsg0ogRM/Nc3DYOhEAlW+xobZo=
 gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=

lib/handler.go

@@ -2,7 +2,6 @@ package lib
 
 import (
 	"net/http"
-	"net/url"
 	"os"
 	"strings"
 
@@ -116,21 +115,16 @@ func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		zap.L().Info("user authorized", zap.String("username", username), zap.String("remote_address", remoteAddr))
 	}
 
-	// Cleanup destination header if it's present by stripping out the prefix
-	// and only keeping the path.
-	if destination := r.Header.Get("Destination"); destination != "" {
-		u, err := url.Parse(destination)
-		if err == nil {
-			destination = strings.TrimPrefix(u.Path, user.Prefix)
-			if !strings.HasPrefix(destination, "/") {
-				destination = "/" + destination
-			}
-			r.Header.Set("Destination", destination)
-		}
+	// Convert the HTTP request into an internal request type
+	req, err := newRequest(r, h.user.Prefix)
+	if err != nil {
+		zap.L().Info("invalid request path or destination", zap.Error(err))
+		http.Error(w, "Invalid request path or destination", http.StatusBadRequest)
+		return
 	}
 
 	// Checks for user permissions relatively to this PATH.
-	allowed := user.Allowed(r, func(filename string) bool {
+	allowed := user.Allowed(req, func(filename string) bool {
 		_, err := user.FileSystem.Stat(r.Context(), filename)
 		return !os.IsNotExist(err)
 	})
@@ -152,8 +146,12 @@ func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	//		"index.html" resource, a human-readable view of the contents of
 	//		the collection, or something else altogether.
 	//
-	// Get, when applied to collection, will return the same as PROPFIND method.
-	if r.Method == "GET" && strings.HasPrefix(r.URL.Path, user.Prefix) {
+	//    Similarly, since the definition of HEAD is a GET without a response
+	// 		message body, the semantics of HEAD are unmodified when applied to
+	// 		collection resources.
+	//
+	// GET (or HEAD), when applied to collection, will return the same as PROPFIND method.
+	if (r.Method == "GET" || r.Method == "HEAD") && strings.HasPrefix(r.URL.Path, user.Prefix) {
 		info, err := user.FileSystem.Stat(r.Context(), strings.TrimPrefix(r.URL.Path, user.Prefix))
 		if err == nil && info.IsDir() {
 			r.Method = "PROPFIND"
@@ -183,5 +181,5 @@ type responseWriterNoBody struct {
 }
 
 func (w responseWriterNoBody) Write(data []byte) (int, error) {
-	return 0, nil
+	return len(data), nil
 }

lib/handler_test.go

@@ -292,6 +292,82 @@ users:
 	require.ErrorContains(t, err, "403")
 }
 
+func TestServerRulesPrefix(t *testing.T) {
+	t.Parallel()
+
+	dir := makeTestDirectory(t, map[string][]byte{
+		"foo.txt":   []byte("foo"),
+		"bar.js":    []byte("foo js"),
+		"a/foo.js":  []byte("foo js"),
+		"a/foo.txt": []byte("foo txt"),
+		"b/foo.txt": []byte("foo b"),
+		"c/a.txt":   []byte("b"),
+		"c/b.txt":   []byte("b"),
+		"c/c.txt":   []byte("b"),
+	})
+
+	srv := makeTestServer(t, fmt.Sprintf(`
+directory: %s
+permissions: CRUD
+prefix: /prefix
+
+users:
+  - username: basic
+    password: basic
+    rules:
+    - regex: "^.+.js$"
+      permissions: R
+    - path: "/b/"
+      permissions: R
+    - path: "/a/foo.txt"
+      permissions: none
+    - path: "/c/"
+      permissions: none
+`, dir))
+
+	client := gowebdav.NewClient(srv.URL, "basic", "basic")
+
+	files, err := client.ReadDir("/prefix")
+	require.NoError(t, err)
+	require.Len(t, files, 5)
+
+	err = client.Write("/prefix/foo.txt", []byte("new"), 0666)
+	require.NoError(t, err)
+
+	err = client.Write("/prefix/new.txt", []byte("new"), 0666)
+	require.NoError(t, err)
+
+	err = client.Copy("/prefix/bar.js", "/prefix/b/bar.js", false)
+	require.ErrorContains(t, err, "403")
+
+	err = client.Copy("/prefix/bar.js", "/prefix/bar.jsx", false)
+	require.NoError(t, err)
+
+	err = client.Copy("/prefix/b/foo.txt", "/prefix/foo1.txt", false)
+	require.NoError(t, err)
+
+	err = client.Rename("/prefix/b/foo.txt", "/prefix/foo2.txt", false)
+	require.ErrorContains(t, err, "403")
+
+	_, err = client.Read("/prefix/a/foo.txt")
+	require.ErrorContains(t, err, "403")
+
+	err = client.Write("/prefix/a/foo.js", []byte("new"), 0666)
+	require.ErrorContains(t, err, "403")
+
+	err = client.Write("/prefix/b/foo.txt", []byte("new"), 0666)
+	require.ErrorContains(t, err, "403")
+
+	_, err = client.ReadDir("/prefix/c")
+	require.ErrorContains(t, err, "403")
+
+	_, err = client.Read("/prefix/c/a.txt")
+	require.ErrorContains(t, err, "403")
+
+	err = client.Write("/prefix/c/b.txt", []byte("new"), 0666)
+	require.ErrorContains(t, err, "403")
+}
+
 func TestServerPermissions(t *testing.T) {
 	t.Parallel()
 

lib/permissions.go

@@ -3,7 +3,6 @@ package lib
 import (
 	"errors"
 	"fmt"
-	"net/http"
 	"path/filepath"
 	"regexp"
 	"strings"
@@ -51,12 +50,12 @@ type UserPermissions struct {
 }
 
 // Allowed checks if the user has permission to access a directory/file
-func (p UserPermissions) Allowed(r *http.Request, fileExists func(string) bool) bool {
+func (p UserPermissions) Allowed(r *request, fileExists func(string) bool) bool {
 	// For COPY and MOVE requests, we first check the permissions for the destination
 	// path. As soon as a rule matches and does not allow the operation at the destination,
 	// we fail immediately. If no rule matches, we check the global permissions.
-	if r.Method == "COPY" || r.Method == "MOVE" {
-		dst := r.Header.Get("Destination")
+	if r.method == "COPY" || r.method == "MOVE" {
+		dst := r.destination
 
 		for i := len(p.Rules) - 1; i >= 0; i-- {
 			if p.Rules[i].Matches(dst) {
@@ -77,7 +76,7 @@ func (p UserPermissions) Allowed(r *http.Request, fileExists func(string) bool)
 	// Go through rules beginning from the last one, and check the permissions at
 	// the source. The first matched rule returns.
 	for i := len(p.Rules) - 1; i >= 0; i-- {
-		if p.Rules[i].Matches(r.URL.Path) {
+		if p.Rules[i].Matches(r.path) {
 			return p.Rules[i].Permissions.Allowed(r, fileExists)
 		}
 	}
@@ -142,8 +141,8 @@ func (p *Permissions) UnmarshalText(data []byte) error {
 
 // Allowed returns whether this permission set has permissions to execute this
 // request in the source directory. This applies to all requests with all methods.
-func (p Permissions) Allowed(r *http.Request, fileExists func(string) bool) bool {
-	switch r.Method {
+func (p Permissions) Allowed(r *request, fileExists func(string) bool) bool {
+	switch r.method {
 	case "GET", "HEAD", "OPTIONS", "POST", "PROPFIND":
 		// Note: POST backend implementation just returns the same thing as GET.
 		return p.Read
@@ -152,7 +151,7 @@ func (p Permissions) Allowed(r *http.Request, fileExists func(string) bool) bool
 	case "PROPPATCH":
 		return p.Update
 	case "PUT":
-		if fileExists(r.URL.Path) {
+		if fileExists(r.path) {
 			return p.Update
 		} else {
 			return p.Create
@@ -172,10 +171,10 @@ func (p Permissions) Allowed(r *http.Request, fileExists func(string) bool) bool
 
 // AllowedDestination returns whether this permissions set has permissions to execute this
 // request in the destination directory. This only applies for COPY and MOVE requests.
-func (p Permissions) AllowedDestination(r *http.Request, fileExists func(string) bool) bool {
-	switch r.Method {
+func (p Permissions) AllowedDestination(r *request, fileExists func(string) bool) bool {
+	switch r.method {
 	case "COPY", "MOVE":
-		if fileExists(r.Header.Get("Destination")) {
+		if fileExists(r.destination) {
 			return p.Update
 		} else {
 			return p.Create

lib/request.go

@@ -0,0 +1,57 @@
+package lib
+
+import (
+	"errors"
+	"net/http"
+	"net/url"
+	"strings"
+)
+
+type request struct {
+	method      string
+	path        string
+	destination string
+}
+
+func newRequest(r *http.Request, prefix string) (*request, error) {
+	ctx := &request{
+		method: r.Method,
+	}
+
+	if destination := r.Header.Get("Destination"); destination != "" {
+		u, err := url.Parse(destination)
+		if err != nil {
+			return nil, errors.New("invalid destination header")
+		}
+
+		if prefix != "" {
+			destination = strings.TrimPrefix(u.Path, prefix)
+			if len(destination) >= len(u.Path) {
+				return nil, errors.New("invalid url prefix")
+			}
+		}
+
+		if !strings.HasPrefix(destination, "/") {
+			destination = "/" + destination
+		}
+
+		ctx.destination = destination
+	}
+
+	path := r.URL.Path
+
+	if prefix != "" {
+		path = strings.TrimPrefix(r.URL.Path, prefix)
+		if len(path) >= len(r.URL.Path) {
+			return nil, errors.New("invalid url prefix")
+		}
+	}
+
+	if !strings.HasPrefix(path, "/") {
+		path = "/" + path
+	}
+
+	ctx.path = path
+
+	return ctx, nil
+}