http: most of a URL shouldn't use URL-escaping

Fixes #502.

R=r, hoisie
CC=golang-dev
https://golang.org/cl/181179

src/pkg/http/request.go

@@ -134,7 +134,7 @@ const defaultUserAgent = "Go http package"
 //
 // If Body is present, "Transfer-Encoding: chunked" is forced as a header.
 func (req *Request) Write(w io.Writer) os.Error {
-	uri := URLEscape(req.URL.Path)
+	uri := urlEscape(req.URL.Path, false)
 	if req.URL.RawQuery != "" {
 		uri += "?" + req.URL.RawQuery
 	}

src/pkg/http/url.go

@@ -128,7 +128,13 @@ func CanonicalPath(path string) string {
 // converting %AB into the byte 0xAB and '+' into ' ' (space).
 // It returns an error if any % is not followed
 // by two hexadecimal digits.
-func URLUnescape(s string) (string, os.Error) {
+func URLUnescape(s string) (string, os.Error) { return urlUnescape(s, true) }
+
+// urlUnescape is like URLUnescape but can be told not to
+// convert + into space.  URLUnescape implements what is
+// called "URL encoding" but that only applies to query strings.
+// Elsewhere in the URL, + does not mean space.
+func urlUnescape(s string, doPlus bool) (string, os.Error) {
 	// Count %, check that they're well-formed.
 	n := 0
 	hasPlus := false
@@ -145,7 +151,7 @@ func URLUnescape(s string) (string, os.Error) {
 			}
 			i += 3
 		case '+':
-			hasPlus = true
+			hasPlus = doPlus
 			i++
 		default:
 			i++
@@ -165,7 +171,11 @@ func URLUnescape(s string) (string, os.Error) {
 			j++
 			i += 3
 		case '+':
-			t[j] = ' '
+			if doPlus {
+				t[j] = ' '
+			} else {
+				t[j] = '+'
+			}
 			j++
 			i++
 		default:
@@ -178,12 +188,14 @@ func URLUnescape(s string) (string, os.Error) {
 }
 
 // URLEscape converts a string into URL-encoded form.
-func URLEscape(s string) string {
+func URLEscape(s string) string { return urlEscape(s, true) }
+
+func urlEscape(s string, doPlus bool) string {
 	spaceCount, hexCount := 0, 0
 	for i := 0; i < len(s); i++ {
 		c := s[i]
 		if shouldEscape(c) {
-			if c == ' ' {
+			if c == ' ' && doPlus {
 				spaceCount++
 			} else {
 				hexCount++
@@ -199,7 +211,7 @@ func URLEscape(s string) string {
 	j := 0
 	for i := 0; i < len(s); i++ {
 		switch c := s[i]; {
-		case c == ' ':
+		case c == ' ' && doPlus:
 			t[j] = '+'
 			j++
 		case shouldEscape(c):
@@ -314,16 +326,16 @@ func ParseURL(rawurl string) (url *URL, err os.Error) {
 		url.Userinfo, url.Host = split(url.Authority, '@', true)
 	}
 
-	if url.Path, err = URLUnescape(path); err != nil {
+	if url.Path, err = urlUnescape(path, false); err != nil {
 		goto Error
 	}
 
 	// Remove escapes from the Authority and Userinfo fields, and verify
 	// that Scheme and Host contain no escapes (that would be illegal).
-	if url.Authority, err = URLUnescape(url.Authority); err != nil {
+	if url.Authority, err = urlUnescape(url.Authority, false); err != nil {
 		goto Error
 	}
-	if url.Userinfo, err = URLUnescape(url.Userinfo); err != nil {
+	if url.Userinfo, err = urlUnescape(url.Userinfo, false); err != nil {
 		goto Error
 	}
 	if strings.Index(url.Scheme, "%") >= 0 {
@@ -349,7 +361,7 @@ func ParseURLReference(rawurlref string) (url *URL, err os.Error) {
 	if url, err = ParseURL(rawurl); err != nil {
 		return nil, err
 	}
-	if url.Fragment, err = URLUnescape(frag); err != nil {
+	if url.Fragment, err = urlUnescape(frag, false); err != nil {
 		return nil, &URLError{"parse", rawurl, err}
 	}
 	return url, nil
@@ -368,16 +380,16 @@ func (url *URL) String() string {
 	if url.Host != "" || url.Userinfo != "" {
 		result += "//"
 		if url.Userinfo != "" {
-			result += URLEscape(url.Userinfo) + "@"
+			result += urlEscape(url.Userinfo, false) + "@"
 		}
 		result += url.Host
 	}
-	result += URLEscape(url.Path)
+	result += urlEscape(url.Path, false)
 	if url.RawQuery != "" {
 		result += "?" + url.RawQuery
 	}
 	if url.Fragment != "" {
-		result += "#" + URLEscape(url.Fragment)
+		result += "#" + urlEscape(url.Fragment, false)
 	}
 	return result
 }

src/pkg/http/url_test.go

@@ -54,7 +54,7 @@ var urltests = []URLTest{
 			"www.google.com", "", "www.google.com",
 			"/file one&two", "", "",
 		},
-		"http://www.google.com/file+one%26two",
+		"http://www.google.com/file%20one%26two",
 	},
 	// user
 	URLTest{
@@ -76,7 +76,7 @@ var urltests = []URLTest{
 			"john doe@www.google.com", "john doe", "www.google.com",
 			"/", "", "",
 		},
-		"ftp://john+doe@www.google.com/",
+		"ftp://john%20doe@www.google.com/",
 	},
 	// query
 	URLTest{
@@ -100,6 +100,17 @@ var urltests = []URLTest{
 		},
 		"",
 	},
+	// %20 outside query
+	URLTest{
+		"http://www.google.com/a%20b?q=c+d",
+		&URL{
+			"http://www.google.com/a%20b?q=c+d",
+			"http", "//www.google.com/a%20b?q=c+d",
+			"www.google.com", "", "www.google.com",
+			"/a b", "q=c+d", "",
+		},
+		"",
+	},
 	// path without /, so no query parsing
 	URLTest{
 		"http:www.google.com/?q=go+language",
@@ -107,9 +118,9 @@ var urltests = []URLTest{
 			"http:www.google.com/?q=go+language",
 			"http", "www.google.com/?q=go+language",
 			"", "", "",
-			"www.google.com/?q=go language", "", "",
+			"www.google.com/?q=go+language", "", "",
 		},
-		"http:www.google.com/%3fq%3dgo+language",
+		"http:www.google.com/%3fq%3dgo%2blanguage",
 	},
 	// non-authority
 	URLTest{