]> Cypherpunks repositories - gostls13.git/commitdiff
add path.Clean and other utilities.
authorRuss Cox <rsc@golang.org>
Tue, 7 Apr 2009 07:40:07 +0000 (00:40 -0700)
committerRuss Cox <rsc@golang.org>
Tue, 7 Apr 2009 07:40:07 +0000 (00:40 -0700)
use path.Clean in web server to sanitize URLs.

http://triv/go/../../../etc/passwd

no longer serves the password file.
it redirects to

http://triv/etc/passwd

which then gets a 404.

R=r
DELTA=288  (286 added, 0 deleted, 2 changed)
OCL=27142
CL=27152

src/lib/Makefile
src/lib/http/server.go
src/lib/path.go [new file with mode: 0644]
src/lib/path_test.go [new file with mode: 0644]

index 4e47f2409a619d03b375c2131473f766cfe3e814..5dc32168af0e0eb6f0ea3709845776ee9d027a1a 100644 (file)
@@ -96,6 +96,7 @@ bufio.6: io.dirinstall os.dirinstall
 exec.6: os.dirinstall
 flag.6: fmt.dirinstall os.dirinstall strconv.dirinstall
 log.6: fmt.dirinstall io.dirinstall os.dirinstall time.dirinstall
+path.6: io.dirinstall
 once.6: sync.dirinstall
 strings.6: utf8.install
 testing.6: flag.install fmt.dirinstall
@@ -103,7 +104,7 @@ testing.6: flag.install fmt.dirinstall
 fmt.dirinstall: io.dirinstall reflect.dirinstall strconv.dirinstall
 go.dirinstall: strconv.dirinstall utf8.install unicode.dirinstall fmt.dirinstall
 hash.dirinstall: os.dirinstall
-http.dirinstall: bufio.install io.dirinstall net.dirinstall os.dirinstall strings.install log.install
+http.dirinstall: bufio.install io.dirinstall net.dirinstall os.dirinstall path.install strings.install log.install
 io.dirinstall: os.dirinstall sync.dirinstall
 json.dirinstall: container.dirinstall fmt.dirinstall io.dirinstall math.dirinstall \
        strconv.dirinstall strings.install utf8.install
index df2ce3698a9ba374617169fb5c64b0b328043aec..fa29e9bc1c22bfcdea143f58cb541fc9e216fa18 100644 (file)
@@ -19,6 +19,7 @@ import (
        "log";
        "net";
        "os";
+       "path";
        "strconv";
 )
 
@@ -209,7 +210,7 @@ func (c *Conn) serve() {
                }
                // HTTP cannot have multiple simultaneous active requests.
                // Until the server replies to this request, it can't read another,
-               // so we might as well run the handler in this thread.
+               // so we might as well run the handler in this goroutine.
                c.handler.ServeHTTP(c, req);
                if c.hijacked {
                        return;
@@ -300,6 +301,10 @@ func RedirectHandler(url string) Handler {
 // so that a handler might register for the two patterns
 // "/codesearch" and "codesearch.google.com/"
 // without taking over requests for http://www.google.com/.
+//
+// ServeMux also takes care of sanitizing the URL request path,
+// redirecting any request containing . or .. elements to an
+// equivalent .- and ..-free URL.
 type ServeMux struct {
        m map[string] Handler
 }
@@ -325,9 +330,33 @@ func pathMatch(pattern, path string) bool {
        return len(path) >= n && path[0:n] == pattern;
 }
 
+// Return the canonical path for p, eliminating . and .. elements.
+func cleanPath(p string) string {
+       if p == "" {
+               return "/";
+       }
+       if p[0] != '/' {
+               p = "/" + p;
+       }
+       np := path.Clean(p);
+       // path.Clean removes trailing slash except for root;
+       // put the trailing slash back if necessary.
+       if p[len(p)-1] == '/' && np != "/" {
+               np += "/";
+       }
+       return np;
+}
+
 // ServeHTTP dispatches the request to the handler whose
 // pattern most closely matches the request URL.
 func (mux *ServeMux) ServeHTTP(c *Conn, req *Request) {
+       // Clean path to canonical form and redirect.
+       if p := cleanPath(req.Url.Path); p != req.Url.Path {
+               c.SetHeader("Location", p);
+               c.WriteHeader(StatusMovedPermanently);
+               return;
+       }
+
        // Most-specific (longest) pattern wins.
        var h Handler;
        var n = 0;
diff --git a/src/lib/path.go b/src/lib/path.go
new file mode 100644 (file)
index 0000000..fdfcd4b
--- /dev/null
@@ -0,0 +1,139 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// The path package implements utility routines for manipulating
+// slash-separated filename paths.
+package path
+
+import "io"
+
+// Clean returns the shortest path name equivalent to path
+// by purely lexical processing.  It applies the following rules
+// iteratively until no further processing can be done:
+//
+//     1. Replace multiple slashes by a single slash.
+//     2. Eliminate each . path name element (the current directory).
+//     3. Eliminate each .. path name element (the parent directory)
+//        along with the non-.. element that precedes it.
+//     4. Eliminate .. elements that begin a rooted path:
+//        that is, replace "/.." by "/" at the beginning of a path.
+//
+// If the result of this process is an empty string, Clean
+// returns the string ".".
+//
+// See also Rob Pike, ``Lexical File Names in Plan 9 or
+// Getting Dot-Dot right,''
+// http://plan9.bell-labs.com/sys/doc/lexnames.html
+func Clean(path string) string {
+       if path == "" {
+               return "."
+       }
+
+       rooted := path[0] == '/';
+       n := len(path);
+
+       // Invariants:
+       //      reading from path; r is index of next byte to process.
+       //      writing to buf; w is index of next byte to write.
+       //      dotdot is index in buf where .. must stop, either because
+       //              it is the leading slash or it is a leading ../../.. prefix.
+       buf := io.StringBytes(path);
+       r, w, dotdot := 0, 0, 0;
+       if rooted {
+               r, w, dotdot = 1, 1, 1;
+       }
+
+       for r < n {
+               switch {
+               case path[r] == '/':
+                       // empty path element
+                       r++;
+               case path[r] == '.' && (r+1 == n || path[r+1] == '/'):
+                       // . element
+                       r++;
+               case path[r] == '.' && path[r+1] == '.' && (r+2 == n || path[r+2] == '/'):
+                       // .. element: remove to last /
+                       r += 2;
+                       switch {
+                       case w > dotdot:
+                               // can backtrack
+                               w--;
+                               for w > dotdot && buf[w] != '/' {
+                                       w--;
+                               }
+                       case !rooted:
+                               // cannot backtrack, but not rooted, so append .. element.
+                               if w > 0 {
+                                       buf[w] = '/';
+                                       w++;
+                               }
+                               buf[w] = '.';
+                               w++;
+                               buf[w] = '.';
+                               w++;
+                               dotdot = w;
+                       }
+               default:
+                       // real path element.
+                       // add slash if needed
+                       if rooted && w != 1 || !rooted && w != 0 {
+                               buf[w] = '/';
+                               w++;
+                       }
+                       // copy element
+                       for ; r < n && path[r] != '/'; r++ {
+                               buf[w] = path[r];
+                               w++;
+                       }
+               }
+       }
+
+       // Turn empty string into "."
+       if w == 0 {
+               buf[w] = '.';
+               w++;
+       }
+
+       return string(buf[0:w]);
+}
+
+// Split splits path immediately following the final slash,
+// separating it into a directory and file name component.
+// If there is no slash in path, DirFile returns an empty dir and
+// file set to path.
+func Split(path string) (dir, file string) {
+       for i := len(path)-1; i >= 0; i-- {
+               if path[i] == '/' {
+                       return path[0:i+1], path[i+1:len(path)];
+               }
+       }
+       return "", path
+}
+
+// Join joins dir and file into a single path, adding a separating
+// slash if necessary.  If dir is empty, it returns file.
+func Join(dir, file string) string {
+       switch {
+       case dir == "":
+               return file;
+       case dir[len(dir)-1] == '/':
+               return dir + file;
+       }
+       return dir + "/" + file;
+}
+
+// Ext returns the file name extension used by path.
+// The extension is the suffix beginning at the final dot
+// in the final slash-separated element of path;
+// it is empty if there is no dot.
+func Ext(path string) string {
+       dot := -1;
+       for i := len(path)-1; i >= 0 && path[i] != '/'; i-- {
+               if path[i] == '.' {
+                       return path[i:len(path)];
+               }
+       }
+       return ""
+}
+
diff --git a/src/lib/path_test.go b/src/lib/path_test.go
new file mode 100644 (file)
index 0000000..067b1d0
--- /dev/null
@@ -0,0 +1,119 @@
+// Copyright 2009 The Go 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 path
+
+import (
+       "path";
+       "testing"
+)
+
+type CleanTest struct {
+       path, clean string
+}
+
+var cleantests = []CleanTest {
+       // Already clean
+       CleanTest{"", "."},
+       CleanTest{"abc", "abc"},
+       CleanTest{"abc/def", "abc/def"},
+       CleanTest{"a/b/c", "a/b/c"},
+       CleanTest{".", "."},
+       CleanTest{"..", ".."},
+       CleanTest{"../..", "../.."},
+       CleanTest{"../../abc", "../../abc"},
+       CleanTest{"/abc", "/abc"},
+       CleanTest{"/", "/"},
+
+       // Remove trailing slash
+       CleanTest{"abc/", "abc"},
+       CleanTest{"abc/def/", "abc/def"},
+       CleanTest{"a/b/c/", "a/b/c"},
+       CleanTest{"./", "."},
+       CleanTest{"../", ".."},
+       CleanTest{"../../", "../.."},
+       CleanTest{"/abc/", "/abc"},
+
+       // Remove doubled slash
+       CleanTest{"abc//def//ghi", "abc/def/ghi"},
+       CleanTest{"//abc", "/abc"},
+       CleanTest{"///abc", "/abc"},
+       CleanTest{"//abc//", "/abc"},
+       CleanTest{"abc//", "abc"},
+
+       // Remove . elements
+       CleanTest{"abc/./def", "abc/def"},
+       CleanTest{"/./abc/def", "/abc/def"},
+       CleanTest{"abc/.", "abc"},
+
+       // Remove .. elements
+       CleanTest{"abc/def/ghi/../jkl", "abc/def/jkl"},
+       CleanTest{"abc/def/../ghi/../jkl", "abc/jkl"},
+       CleanTest{"abc/def/..", "abc"},
+       CleanTest{"abc/def/../..", "."},
+       CleanTest{"/abc/def/../..", "/"},
+       CleanTest{"abc/def/../../..", ".."},
+       CleanTest{"/abc/def/../../..", "/"},
+       CleanTest{"abc/def/../../../ghi/jkl/../../../mno", "../../mno"},
+
+       // Combinations
+       CleanTest{"abc/./../def", "def"},
+       CleanTest{"abc//./../def", "def"},
+       CleanTest{"abc/../../././../def", "../../def"},
+}
+
+func TestClean(t *testing.T) {
+       for i, test := range cleantests {
+               if s := Clean(test.path); s != test.clean {
+                       t.Errorf("Clean(%q) = %q, want %q", test.path, s, test.clean);
+               }
+       }
+}
+
+type SplitTest struct {
+       path, dir, file string
+}
+
+var splittests = []SplitTest {
+       SplitTest{"a/b", "a/", "b"},
+       SplitTest{"a/b/", "a/b/", ""},
+       SplitTest{"a/", "a/", ""},
+       SplitTest{"a", "", "a"},
+       SplitTest{"/", "/", ""},
+}
+
+func TestSplit(t *testing.T) {
+       for i, test := range splittests {
+               if d, f := Split(test.path); d != test.dir || f != test.file {
+                       t.Errorf("Split(%q) = %q, %q, want %q, %q", test.path, d, f, test.dir, test.file);
+               }
+       }
+}
+
+type JoinTest struct {
+       dir, file, path string
+}
+
+var jointests = []JoinTest {
+       JoinTest{"a", "b", "a/b"},
+       JoinTest{"a", "", "a/"},
+       JoinTest{"", "b", "b"},
+       JoinTest{"/", "a", "/a"},
+       JoinTest{"/", "", "/"},
+       JoinTest{"a/", "b", "a/b"},
+       JoinTest{"a/", "", "a/"},
+}
+
+type ExtTest struct {
+       path, ext string
+}
+
+var exttests = []ExtTest {
+       ExtTest{"path.go", ".go"},
+       ExtTest{"path.pb.go", ".go"},
+       ExtTest{"path", ""},
+       ExtTest{"a.dir/b", ""},
+       ExtTest{"a.dir/b.go", ".go"},
+       ExtTest{"a.dir/", ""},
+}