net: don't error when marshalling nil IP addresses

See https://code.google.com/p/go/issues/detail?id=6339#c3

Fixes #6339

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/13553044

diff --git a/src/pkg/net/ip.go b/src/pkg/net/ip.go
index b73804d5287e40c04a7268e1153e065b1f924ab5..f0f0d9ec6bddd0543d84f6ef8435df037ccb9767 100644 (file)
--- a/src/pkg/net/ip.go
+++ b/src/pkg/net/ip.go
@@ -315,6 +315,9 @@ func (ip IP) String() string {
 // MarshalText implements the encoding.TextMarshaler interface.
 // The encoding is the same as returned by String.
 func (ip IP) MarshalText() ([]byte, error) {
+       if len(ip) == 0 {
+               return []byte(""), nil
+       }
        if len(ip) != IPv4len && len(ip) != IPv6len {
                return nil, errors.New("invalid IP address")
        }
@@ -324,6 +327,10 @@ func (ip IP) MarshalText() ([]byte, error) {
 // UnmarshalText implements the encoding.TextUnmarshaler interface.
 // The IP address is expected in a form accepted by ParseIP.
 func (ip *IP) UnmarshalText(text []byte) error {
+       if len(text) == 0 {
+               *ip = nil
+               return nil
+       }
        s := string(text)
        x := ParseIP(s)
        if x == nil {

diff --git a/src/pkg/net/ip_test.go b/src/pkg/net/ip_test.go
index 606344d265592abbb70d4ccf98fb3dcea3281004..5fcc8257af67ba68bec3f542f63837c0cbffd1a2 100644 (file)
--- a/src/pkg/net/ip_test.go
+++ b/src/pkg/net/ip_test.go
@@ -32,14 +32,35 @@ func TestParseIP(t *testing.T) {
                if out := ParseIP(tt.in); !reflect.DeepEqual(out, tt.out) {
                        t.Errorf("ParseIP(%q) = %v, want %v", tt.in, out, tt.out)
                }
+               if tt.in == "" {
+                       // Tested in TestMarshalEmptyIP below.
+                       continue
+               }
                var out IP
-
                if err := out.UnmarshalText([]byte(tt.in)); !reflect.DeepEqual(out, tt.out) || (tt.out == nil) != (err != nil) {
                        t.Errorf("IP.UnmarshalText(%q) = %v, %v, want %v", tt.in, out, err, tt.out)
                }
        }
 }
 
+// Issue 6339
+func TestMarshalEmptyIP(t *testing.T) {
+       for _, in := range [][]byte{nil, []byte("")} {
+               var out = IP{1, 2, 3, 4}
+               if err := out.UnmarshalText(in); err != nil || out != nil {
+                       t.Errorf("UnmarshalText(%v) = %v, %v; want nil, nil", in, out, err)
+               }
+       }
+       var ip IP
+       got, err := ip.MarshalText()
+       if err != nil {
+               t.Fatal(err)
+       }
+       if !reflect.DeepEqual(got, []byte("")) {
+               t.Errorf(`got %#v, want []byte("")`, got)
+       }
+}
+
 var ipStringTests = []struct {
        in  IP
        out string // see RFC 5952
@@ -53,23 +74,19 @@ var ipStringTests = []struct {
        {IP{0x20, 0x1, 0xd, 0xb8, 0, 0, 0, 0, 0, 0x1, 0, 0, 0, 0, 0, 0x1}, "2001:db8::1:0:0:1"},
        {IP{0x20, 0x1, 0xD, 0xB8, 0, 0, 0, 0, 0, 0xA, 0, 0xB, 0, 0xC, 0, 0xD}, "2001:db8::a:b:c:d"},
        {IPv4(192, 168, 0, 1), "192.168.0.1"},
-       {nil, "<nil>"},
+       {nil, ""},
 }
 
 func TestIPString(t *testing.T) {
        for _, tt := range ipStringTests {
-               if out := tt.in.String(); out != tt.out {
-                       t.Errorf("IP.String(%v) = %q, want %q", tt.in, out, tt.out)
-               }
                if tt.in != nil {
-                       if out, err := tt.in.MarshalText(); string(out) != tt.out || err != nil {
-                               t.Errorf("IP.MarshalText(%v) = %q, %v, want %q, nil", out, err, tt.out)
-                       }
-               } else {
-                       if _, err := tt.in.MarshalText(); err == nil {
-                               t.Errorf("IP.MarshalText(nil) succeeded, want failure")
+                       if out := tt.in.String(); out != tt.out {
+                               t.Errorf("IP.String(%v) = %q, want %q", tt.in, out, tt.out)
                        }
                }
+               if out, err := tt.in.MarshalText(); string(out) != tt.out || err != nil {
+                       t.Errorf("IP.MarshalText(%v) = %q, %v, want %q, nil", out, err, tt.out)
+               }
        }
 }