netipx: remove redundant CompareAddr, change ComparePrefix definition

Signed-off-by: Brad Fitzpatrick <[email protected]>

netipx.go

@@ -546,32 +546,24 @@ func appendRangePrefixes(dst []netip.Prefix, makePrefix prefixMaker, a, b uint12
 	return dst
 }
 
-// CompareAddr returns -1 if a.Less(b), 1 if b.Less(0), else it
-// returns 0.
-func CompareAddr(a, b netip.Addr) int {
-	if a.Less(b) {
-		return -1
-	}
-	if b.Less(a) {
-		return 1
-	}
-	return 0
-}
-
-// ComparePrefix  -1 if a.Addr().Less(b), 1 if
-// b.Addr().Less(0), else if a and b have the same address, it
-// compares their prefix bit length, returning -1, 0, or 1.
+// ComparePrefix is a compare function (returning -1, 0 or 1)
+// sorting prefixes first by address family (IPv4 before IPv6),
+// then by prefix length (smaller prefixes first), then by
+// address.
 func ComparePrefix(a, b netip.Prefix) int {
 	aa, ba := a.Addr(), b.Addr()
-	if aa == ba {
-		ab, bb := a.Bits(), b.Bits()
-		if ab < bb {
+	if al, bl := aa.BitLen(), ba.BitLen(); al != bl {
+		if al < bl {
 			return -1
 		}
-		if bb < ab {
-			return 1
+		return 1
+	}
+	ab, bb := a.Bits(), b.Bits()
+	if ab != bb {
+		if ab < bb {
+			return -1
 		}
-		return 0
+		return 1
 	}
-	return CompareAddr(a.Addr(), b.Addr())
+	return aa.Compare(ba)
 }

netipx_test.go

@@ -872,33 +872,23 @@ func TestNoAllocs(t *testing.T) {
 	})
 }
 
-func TestCompareAddr(t *testing.T) {
-	tests := []struct {
-		a, b string
-		want int
-	}{
-		{"1.1.1.1", "1.1.1.2", -1},
-		{"1.1.1.2", "1.1.1.1", 1},
-		{"1.1.1.1", "1.1.1.1", 0},
-		{"1.1.1.1", "1::1", -1},
-	}
-	for _, tt := range tests {
-		if got := CompareAddr(netip.MustParseAddr(tt.a), netip.MustParseAddr(tt.b)); got != tt.want {
-			t.Errorf("f(%q, %q) = %v; want %v", tt.a, tt.b, got, tt.want)
-		}
-	}
-}
-
 func TestComparePrefix(t *testing.T) {
 	tests := []struct {
 		a, b string
 		want int
 	}{
-		{"1.1.1.1/10", "1.1.1.2/10", -1},
-		{"1.1.1.2/10", "1.1.1.1/10", 1},
-		{"1.1.1.1/10", "1.1.1.1/10", 0},
-		{"1.1.1.1/9", "1.1.1.1/10", -1},
-		{"1.1.1.1/32", "1::1/128", -1},
+		// sort by address family
+		{"1.0.0.0/8", "1::/8", -1},
+		{"1::/8", "1.0.0.0/8", 1},
+
+		// then sort by bitlen
+		{"1.0.0.0/7", "1.0.0.0/8", -1},
+		{"1.0.0.0/8", "1.0.0.0/7", 1},
+		{"1.0.0.0/8", "1.0.0.0/8", 0},
+
+		// then sort by addr
+		{"1.0.0.0/8", "1.0.0.1/8", -1},
+		{"1.0.0.1/8", "1.0.0.0/8", 1},
 	}
 	for _, tt := range tests {
 		if got := ComparePrefix(netip.MustParsePrefix(tt.a), netip.MustParsePrefix(tt.b)); got != tt.want {