dht: We can now message nodes with no ID if there's nothing better

diff --git a/dht/dht.go b/dht/dht.go
index d688f770b9af79d25bd4ad91204fd20ba1a1c149..d1abce948e239d182a44933d1e674e86889f64bc 100644 (file)
--- a/dht/dht.go
+++ b/dht/dht.go
@@ -1104,8 +1104,33 @@ func (me bitCountDistance) IsZero() bool {
 }
 
 // Below are 2 versions of idDistance. Only one can be active.
+var maxDistance big.Int
 
+func init() {
+       var zero big.Int
+       maxDistance.SetBit(&zero, 160, 1)
+}
+
+// If we don't know the ID for a node, then its distance is more than the
+// furthest possible distance otherwise.
 func idDistance(a, b string) (ret bigIntDistance) {
+       if a == "" && b == "" {
+               return
+       }
+       if a == "" {
+               if len(b) != 20 {
+                       panic(b)
+               }
+               ret.Set(&maxDistance)
+               return
+       }
+       if b == "" {
+               if len(a) != 20 {
+                       panic(a)
+               }
+               ret.Set(&maxDistance)
+               return
+       }
        if len(a) != 20 {
                panic(a)
        }

diff --git a/dht/dht_test.go b/dht/dht_test.go
index 5b5b5d1d5fdbe055a9069c97feafc9ec5b6c60ba..137aa1366ee2f6e37ef0a4bba7afd119be323f86 100644 (file)
--- a/dht/dht_test.go
+++ b/dht/dht_test.go
@@ -52,6 +52,7 @@ var testIDs = []string{
        "\x03" + zeroID[1:18] + "\x55\xf0",
        "\x55" + zeroID[1:17] + "\xff\x55\x0f",
        "\x54" + zeroID[1:18] + "\x50\x0f",
+       "",
 }
 
 func TestDistances(t *testing.T) {
@@ -64,21 +65,38 @@ func TestDistances(t *testing.T) {
        if idDistance(testIDs[3], testIDs[2]).BitCount() != 4+8+8 {
                t.FailNow()
        }
+       for i := 0; i < 5; i++ {
+               dist := idDistance(testIDs[i], testIDs[5]).Int
+               if dist.Cmp(&maxDistance) != 0 {
+                       t.FailNow()
+               }
+       }
+}
+
+func TestMaxDistanceString(t *testing.T) {
+       if string(maxDistance.Bytes()) != "\x01"+zeroID {
+               t.FailNow()
+       }
 }
 
 func TestBadIdStrings(t *testing.T) {
        var a, b string
+       idDistance(a, b)
+       idDistance(a, zeroID)
+       idDistance(zeroID, b)
        recoverPanicOrDie(t, func() {
-               idDistance(a, b)
+               idDistance("when", a)
        })
        recoverPanicOrDie(t, func() {
-               idDistance(a, zeroID)
+               idDistance(a, "bad")
        })
        recoverPanicOrDie(t, func() {
-               idDistance(zeroID, b)
+               idDistance("meets", "evil")
        })
-       if !idDistance(zeroID, zeroID).IsZero() {
-               t.Fatal("identical IDs should have distance 0")
+       for _, id := range testIDs {
+               if !idDistance(id, id).IsZero() {
+                       t.Fatal("identical IDs should have distance 0")
+               }
        }
        a = "\x03" + zeroID[1:]
        b = zeroID