feat(ipconverter): add a tool to convert IPv4 to int and vice-versa

It's sometimes useful to store IPv4 addresses as an integer. This tool
helps with the conversion, and also does the reverse conversion.

```
% go run . int2ip 3232235521
3232235521      192.168.0.1
% go run . ip2int 192.168.0.1
192.168.0.1     3232235521
```

Change-Id: Ic1e44057bca3539b4c183d387c635f69f5bf3f36
Reviewed-on: https://cl.fcuny.net/c/world/+/441
Tested-by: CI
Reviewed-by: Franck Cuny <franck@fcuny.net>

1 files changed, 44 insertions, 0 deletions

diff --git a/tools/ipconverter/main_test.go b/tools/ipconverter/main_test.go
new file mode 100644
index 0000000..394dc28
--- /dev/null
+++ b/tools/ipconverter/main_test.go
@@ -0,0 +1,44 @@
+package main
+
+import (
+	"math/big"
+	"testing"
+)
+
+func TestIPtoInt(t *testing.T) {
+
+	tests := map[string]*big.Int{
+		"192.168.0.1": big.NewInt(3232235521),
+		"10.0.0.1":    big.NewInt(167772161),
+	}
+	for test := range tests {
+		r, err := IPtoInt(test)
+		if err != nil {
+			t.Errorf("failed to convert %s to an int: %s", test, err)
+		}
+		if r.Cmp(tests[test]) != 0 {
+			t.Errorf("convert %s to int, got %d expected %d", test, r, tests[test])
+		}
+	}
+
+	if _, err := IPtoInt("10"); err == nil {
+		t.Error("calling IPtoInt with invalid IP did not result in error")
+	}
+}
+
+
+func TestIPtoN(t *testing.T) {
+	tests := map[string]string{
+		"3232235521": "192.168.0.1",
+		"167772161": "10.0.0.1",
+	}
+	for test := range tests {
+		r, err := IPtoN(test)
+		if err != nil {
+			t.Errorf("failed to convert %s to an address: %s", test, err)
+		}
+		if r != tests[test] {
+			t.Errorf("convert %s to address, got %s expected %s", test, r, tests[test])
+		}
+	}
+}