make Location translate relative path to absolute

(HTTP requires absolute in protocol).

add URL tests

R=r
DELTA=243  (242 added, 0 deleted, 1 changed)
OCL=27472
CL=27523

src/lib/http/server.go

@@ -269,6 +269,49 @@ func NotFoundHandler() Handler {
 // Redirect replies to the request with a redirect to url,
 // which may be a path relative to the request path.
 func Redirect(c *Conn, url string) {
+	u, err := ParseURL(url);
+	if err != nil {
+		// TODO report internal error instead?
+		c.SetHeader("Location", url);
+		c.WriteHeader(StatusMovedPermanently);
+	}
+
+	// If url was relative, make absolute by
+	// combining with request path.
+	// The browser would probably do this for us,
+	// but doing it ourselves is more reliable.
+
+	// NOTE(rsc): RFC 2616 says that the Location
+	// line must be an absolute URI, like
+	// "http://www.google.com/redirect/",
+	// not a path like "/redirect/".
+	// Unfortunately, we don't know what to
+	// put in the host name section to get the
+	// client to connect to us again, so we can't
+	// know the right absolute URI to send back.
+	// Because of this problem, no one pays attention
+	// to the RFC; they all send back just a new path.
+	// So do we.
+	oldpath := c.Req.Url.Path;
+	if oldpath == "" {	// should not happen, but avoid a crash if it does
+		oldpath = "/"
+	}
+	if u.Scheme == "" {
+		// no leading http://server
+		if url == "" || url[0] != '/' {
+			// make relative path absolute
+			olddir, oldfile := path.Split(oldpath);
+			url = olddir + url;
+		}
+
+		// clean up but preserve trailing slash
+		trailing := url[len(url) - 1] == '/';
+		url = path.Clean(url);
+		if trailing && url[len(url) - 1] != '/' {
+			url += "/";
+		}
+	}
+
 	c.SetHeader("Location", url);
 	c.WriteHeader(StatusMovedPermanently);
 }

src/lib/http/url.go

@@ -3,7 +3,7 @@
 // license that can be found in the LICENSE file.
 
 // Parse URLs (actually URIs, but that seems overly pedantic).
-// TODO(rsc): Add tests.
+// RFC 2396
 
 package http
 
@@ -196,3 +196,29 @@ func ParseURLReference(rawurlref string) (url *URL, err *os.Error) {
 	return url, nil
 }
 
+// String reassembles url into a valid URL string.
+//
+// There are redundant fields stored in the URL structure:
+// the String method consults Scheme, Path, Host, Userinfo,
+// Query, and Fragment, but not RawPath or Authority.
+func (url *URL) String() string {
+	result := "";
+	if url.Scheme != "" {
+		result += url.Scheme + ":";
+	}
+	if url.Host != "" || url.Userinfo != "" {
+		result += "//";
+		if url.Userinfo != "" {
+			result += url.Userinfo + "@";
+		}
+		result += url.Host;
+	}
+	result += url.Path;
+	if url.Query != "" {
+		result += "?" + url.Query;
+	}
+	if url.Fragment != "" {
+		result += "#" + url.Fragment;
+	}
+	return result;
+}

src/lib/http/url_test.go

+// 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 http
+
+import (
+	"fmt";
+	"http";
+	"os";
+	"reflect";
+	"testing";
+)
+
+// TODO(rsc):
+//	test URLUnescape
+// 	test URLEscape
+//	test ParseURL
+
+type URLTest struct {
+	in string;
+	out *URL;
+}
+
+var urltests = []URLTest {
+	// no path
+	URLTest{
+		"http://www.google.com",
+		&URL{
+			"http://www.google.com",
+			"http", "//www.google.com",
+			"www.google.com", "", "www.google.com",
+			"", "", ""
+		}
+	},
+	// path
+	URLTest{
+		"http://www.google.com/",
+		&URL{
+			"http://www.google.com/",
+			"http", "//www.google.com/",
+			"www.google.com", "", "www.google.com",
+			"/", "", ""
+		}
+	},
+	// user
+	URLTest{
+		"ftp://webmaster@www.google.com/",
+		&URL{
+			"ftp://webmaster@www.google.com/",
+			"ftp", "//webmaster@www.google.com/",
+			"webmaster@www.google.com", "webmaster", "www.google.com",
+			"/", "", ""
+		}
+	},
+	// query
+	URLTest{
+		"http://www.google.com/?q=go+language",
+		&URL{
+			"http://www.google.com/?q=go+language",
+			"http", "//www.google.com/?q=go+language",
+			"www.google.com", "", "www.google.com",
+			"/", "q=go+language", ""
+		}
+	},
+	// path without /, so no query parsing
+	URLTest{
+		"http:www.google.com/?q=go+language",
+		&URL{
+			"http:www.google.com/?q=go+language",
+			"http", "www.google.com/?q=go+language",
+			"", "", "",
+			"www.google.com/?q=go+language", "", ""
+		}
+	},
+	// non-authority
+	URLTest{
+		"mailto:/webmaster@golang.org",
+		&URL{
+			"mailto:/webmaster@golang.org",
+			"mailto", "/webmaster@golang.org",
+			"", "", "",
+			"/webmaster@golang.org", "", ""
+		}
+	},
+	// non-authority
+	URLTest{
+		"mailto:webmaster@golang.org",
+		&URL{
+			"mailto:webmaster@golang.org",
+			"mailto", "webmaster@golang.org",
+			"", "", "",
+			"webmaster@golang.org", "", ""
+		}
+	},
+}
+
+var urlnofragtests = []URLTest {
+	URLTest{
+		"http://www.google.com/?q=go+language#foo",
+		&URL{
+			"http://www.google.com/?q=go+language#foo",
+			"http", "//www.google.com/?q=go+language#foo",
+			"www.google.com", "", "www.google.com",
+			"/", "q=go+language#foo", ""
+		}
+	},
+}
+
+var urlfragtests = []URLTest {
+	URLTest{
+		"http://www.google.com/?q=go+language#foo",
+		&URL{
+			"http://www.google.com/?q=go+language",
+			"http", "//www.google.com/?q=go+language",
+			"www.google.com", "", "www.google.com",
+			"/", "q=go+language", "foo"
+		}
+	},
+}
+
+// more useful string for debugging than fmt's struct printer
+func ufmt(u *URL) string {
+	return fmt.Sprintf("%q, %q, %q, %q, %q, %q, %q, %q, %q",
+		u.Raw, u.Scheme, u.RawPath, u.Authority, u.Userinfo,
+		u.Host, u.Path, u.Query, u.Fragment);
+}
+
+func DoTest(t *testing.T, parse func(string) (*URL, *os.Error), name string, tests []URLTest) {
+	for i, tt := range tests {
+		u, err := parse(tt.in);
+		if err != nil {
+			t.Errorf("%s(%q) returned error %s", name, tt.in, err);
+			continue;
+		}
+		if !reflect.DeepEqual(u, tt.out) {
+			t.Errorf("%s(%q):\n\thave %v\n\twant %v\n",
+				name, tt.in, ufmt(u), ufmt(tt.out));
+		}
+	}
+}
+
+func TestParseURL(t *testing.T) {
+	DoTest(t, ParseURL, "ParseURL", urltests);
+	DoTest(t, ParseURL, "ParseURL", urlnofragtests);
+}
+
+func TestParseURLReference(t *testing.T) {
+	DoTest(t, ParseURLReference, "ParseURLReference", urltests);
+	DoTest(t, ParseURLReference, "ParseURLReference", urlfragtests);
+}
+
+func DoTestString(t *testing.T, parse func(string) (*URL, *os.Error), name string, tests []URLTest) {
+	for i, tt := range tests {
+		u, err := parse(tt.in);
+		if err != nil {
+			t.Errorf("%s(%q) returned error %s", name, tt.in, err);
+			continue;
+		}
+		s := u.String();
+		if s != tt.in {
+			t.Errorf("%s(%q).String() == %q", tt.in, s);
+		}
+	}
+}
+
+func TestURLString(t *testing.T) {
+	DoTestString(t, ParseURL, "ParseURL", urltests);
+	DoTestString(t, ParseURL, "ParseURL", urlfragtests);
+	DoTestString(t, ParseURL, "ParseURL", urlnofragtests);
+	DoTestString(t, ParseURLReference, "ParseURLReference", urltests);
+	DoTestString(t, ParseURLReference, "ParseURLReference", urlfragtests);
+	DoTestString(t, ParseURLReference, "ParseURLReference", urlnofragtests);
+}