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net/url: allow Parse, ParseRequestURI to parse ipv6 zone identifiers …
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…in URIs

Using IPv6 link-local addresses to make connections between on-link
nodes is useful for small distributed applications but it requires zone
identifiers to distinguish a correct IP link. It's the same for
transports using URI for destination discovery such as HTTP, WebSocket.

This change allows Parse, ParseRequestURI functions and String method of
URL to parse/return a literal IPv6 address followed by a zone identifier
within a URI as described in RFC 6874.

Fixes #6530.

Change-Id: I2936ea65c1446994770cf2ee2c28a1c73faaa0ca
Reviewed-on: https://go-review.googlesource.com/2431
Reviewed-by: Brad Fitzpatrick <[email protected]>
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@cixtor
cixtor committed Apr 7, 2015
1 parent aaa092c commit 8e95654
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Showing 2 changed files with 178 additions and 13 deletions.
85 changes: 73 additions & 12 deletions src/net/url/url.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -51,6 +51,7 @@ type encoding int

const (
encodePath encoding = 1 + iota
encodeHost
encodeUserPassword
encodeQueryComponent
encodeFragment
Expand All @@ -64,6 +65,9 @@ func (e EscapeError) Error() string {

// Return true if the specified character should be escaped when
// appearing in a URL string, according to RFC 3986.
//
// Please be informed that for now shouldEscape does not check all
// reserved characters correctly. See golang.org/issue/5684.
func shouldEscape(c byte, mode encoding) bool {
// §2.3 Unreserved characters (alphanum)
if 'A' <= c && c <= 'Z' || 'a' <= c && c <= 'z' || '0' <= c && c <= '9' {
Expand Down Expand Up @@ -92,6 +96,10 @@ func shouldEscape(c byte, mode encoding) bool {
// that too.
return c == '@' || c == '/' || c == '?' || c == ':'

case encodeHost: // §3.2.1
// The RFC allows ':'.
return c != ':'

case encodeQueryComponent: // §3.4
// The RFC reserves (so we must escape) everything.
return true
Expand All @@ -101,6 +109,13 @@ func shouldEscape(c byte, mode encoding) bool {
// everything, so escape nothing.
return false
}

case '[', ']': // §2.2 Reserved characters (reserved)
switch mode {
case encodeHost: // §3.2.1
// The RFC allows '[', ']'.
return false
}
}

// Everything else must be escaped.
Expand Down Expand Up @@ -401,10 +416,6 @@ func parse(rawurl string, viaRequest bool) (url *URL, err error) {
if err != nil {
goto Error
}
if strings.Contains(url.Host, "%") {
err = errors.New("hexadecimal escape in host")
goto Error
}
}
if url.Path, err = unescape(rest, encodePath); err != nil {
goto Error
Expand All @@ -418,26 +429,76 @@ Error:
func parseAuthority(authority string) (user *Userinfo, host string, err error) {
i := strings.LastIndex(authority, "@")
if i < 0 {
host = authority
return
host, err = parseHost(authority)
} else {
host, err = parseHost(authority[i+1:])
}
userinfo, host := authority[:i], authority[i+1:]
if err != nil {
return nil, "", err
}
if i < 0 {
return nil, host, nil
}
userinfo := authority[:i]
if strings.Index(userinfo, ":") < 0 {
if userinfo, err = unescape(userinfo, encodeUserPassword); err != nil {
return
return nil, "", err
}
user = User(userinfo)
} else {
username, password := split(userinfo, ":", true)
if username, err = unescape(username, encodeUserPassword); err != nil {
return
return nil, "", err
}
if password, err = unescape(password, encodeUserPassword); err != nil {
return
return nil, "", err
}
user = UserPassword(username, password)
}
return
return user, host, nil
}

// parseHost parses host as an authority without user information.
func parseHost(host string) (string, error) {
litOrName := host
if strings.HasPrefix(host, "[") {
// Parse an IP-Literal in RFC 3986 and RFC 6874.
// E.g., "[fe80::1], "[fe80::1%25en0]"
//
// RFC 4007 defines "%" as a delimiter character in
// the textual representation of IPv6 addresses.
// Per RFC 6874, in URIs that "%" is encoded as "%25".
i := strings.LastIndex(host[1:], "]")
if i < 0 {
return "", errors.New("missing ']' in host")
}
// Parse a host subcomponent without a ZoneID in RFC
// 6874 because the ZoneID is allowed to use the
// percent encoded form.
j := strings.Index(host[1:1+i], "%25")
if j < 0 {
litOrName = host[1 : 1+i]
} else {
litOrName = host[1 : 1+j]
}
}
// A URI containing an IP-Literal without a ZoneID or
// IPv4address in RFC 3986 and RFC 6847 must not be
// percent-encoded.
//
// A URI containing a DNS registered name in RFC 3986 is
// allowed to be percent-encoded, though we don't use it for
// now to avoid messing up with the gap between allowed
// characters in URI and allowed characters in DNS.
// See golang.org/issue/7991.
if strings.Contains(litOrName, "%") {
return "", errors.New("percent-encoded characters in host")
}
var err error
if host, err = unescape(host, encodeHost); err != nil {
return "", err
}
return host, nil
}

// String reassembles the URL into a valid URL string.
Expand Down Expand Up @@ -475,7 +536,7 @@ func (u *URL) String() string {
buf.WriteByte('@')
}
if h := u.Host; h != "" {
buf.WriteString(h)
buf.WriteString(escape(h, encodeHost))
}
}
if u.Path != "" && u.Path[0] != '/' && u.Host != "" {
Expand Down
106 changes: 105 additions & 1 deletion src/net/url/url_test.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -289,6 +289,86 @@ var urltests = []URLTest{
},
"",
},
// host subcomponent; IPv4 address in RFC 3986
{
"http://192.168.0.1/",
&URL{
Scheme: "http",
Host: "192.168.0.1",
Path: "/",
},
"",
},
// host and port subcomponents; IPv4 address in RFC 3986
{
"http://192.168.0.1:8080/",
&URL{
Scheme: "http",
Host: "192.168.0.1:8080",
Path: "/",
},
"",
},
// host subcomponent; IPv6 address in RFC 3986
{
"http://[fe80::1]/",
&URL{
Scheme: "http",
Host: "[fe80::1]",
Path: "/",
},
"",
},
// host and port subcomponents; IPv6 address in RFC 3986
{
"http://[fe80::1]:8080/",
&URL{
Scheme: "http",
Host: "[fe80::1]:8080",
Path: "/",
},
"",
},
// host subcomponent; IPv6 address with zone identifier in RFC 6847
{
"http://[fe80::1%25en0]/", // alphanum zone identifier
&URL{
Scheme: "http",
Host: "[fe80::1%en0]",
Path: "/",
},
"",
},
// host and port subcomponents; IPv6 address with zone identifier in RFC 6847
{
"http://[fe80::1%25en0]:8080/", // alphanum zone identifier
&URL{
Scheme: "http",
Host: "[fe80::1%en0]:8080",
Path: "/",
},
"",
},
// host subcomponent; IPv6 address with zone identifier in RFC 6847
{
"http://[fe80::1%25%65%6e%301-._~]/", // percent-encoded+unreserved zone identifier
&URL{
Scheme: "http",
Host: "[fe80::1%en01-._~]",
Path: "/",
},
"http://[fe80::1%25en01-._~]/",
},
// host and port subcomponents; IPv6 address with zone identifier in RFC 6847
{
"http://[fe80::1%25%65%6e%301-._~]:8080/", // percent-encoded+unreserved zone identifier
&URL{
Scheme: "http",
Host: "[fe80::1%en01-._~]:8080",
Path: "/",
},
"http://[fe80::1%25en01-._~]:8080/",
},
}

// more useful string for debugging than fmt's struct printer
Expand Down Expand Up @@ -358,9 +438,33 @@ var parseRequestURLTests = []struct {
{"/", true},
{pathThatLooksSchemeRelative, true},
{"//not.a.user@%66%6f%6f.com/just/a/path/also", true},
{"*", true},
{"http://192.168.0.1/", true},
{"http://192.168.0.1:8080/", true},
{"http://[fe80::1]/", true},
{"http://[fe80::1]:8080/", true},

// Tests exercising RFC 6874 compliance:
{"http://[fe80::1%25en0]/", true}, // with alphanum zone identifier
{"http://[fe80::1%25en0]:8080/", true}, // with alphanum zone identifier
{"http://[fe80::1%25%65%6e%301-._~]/", true}, // with percent-encoded+unreserved zone identifier
{"http://[fe80::1%25%65%6e%301-._~]:8080/", true}, // with percent-encoded+unreserved zone identifier

{"foo.html", false},
{"../dir/", false},
{"*", true},
{"http://192.168.0.%31/", false},
{"http://192.168.0.%31:8080/", false},
{"http://[fe80::%31]/", false},
{"http://[fe80::%31]:8080/", false},
{"http://[fe80::%31%25en0]/", false},
{"http://[fe80::%31%25en0]:8080/", false},

// These two cases are valid as textual representations as
// described in RFC 4007, but are not valid as address
// literals with IPv6 zone identifiers in URIs as described in
// RFC 6874.
{"http://[fe80::1%en0]/", false},
{"http://[fe80::1%en0]:8080/", false},
}

func TestParseRequestURI(t *testing.T) {
Expand Down

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