middleware/httpproxy: Add (#439)

This PR adds a middleware that talks to dns.google.com over HTTPS,
meaning all your DNS traffic is encrypted when traversing your ISP and
the internet.

The `dns.google.com` address is re-resolved every 30 seconds.

middleware/httpproxy/setup_test.go

@@ -0,0 +1,68 @@
+package httpproxy
+
+import (
+	"io/ioutil"
+	"os"
+	"strings"
+	"testing"
+
+	"github.com/mholt/caddy"
+)
+
+func TestSetupChaos(t *testing.T) {
+	tests := []struct {
+		input              string
+		shouldErr          bool
+		expectedFrom       string // expected from.
+		expectedErrContent string // substring from the expected error. Empty for positive cases.
+	}{
+		// ok
+		{
+			`httpproxy . dns.google.com`, false, "", "",
+		},
+		{
+			`httpproxy . dns.google.com {
+				upstream 8.8.8.8:53
+			}`, false, "", "",
+		},
+		{
+			`httpproxy . dns.google.com {
+				upstream resolv.conf
+			}`, false, "", "",
+		},
+		// fail
+		{
+			`httpproxy`, true, "", "Wrong argument count or unexpected line ending after",
+		},
+		{
+			`httpproxy . wns.google.com`, true, "", "unknown http proxy",
+		},
+	}
+
+	// Write fake resolv.conf for test
+	err := ioutil.WriteFile("resolv.conf", []byte("nameserver 127.0.0.1\n"), 0600)
+	if err != nil {
+		t.Fatalf("Failed to write test resolv.conf")
+	}
+	defer os.Remove("resolv.conf")
+
+	for i, test := range tests {
+		c := caddy.NewTestController("dns", test.input)
+		_, err := httpproxyParse(c)
+
+		if test.shouldErr && err == nil {
+			t.Errorf("Test %d: Expected error but found %s for input %s", i, err, test.input)
+		}
+
+		if err != nil {
+			t.Logf("%q", err)
+			if !test.shouldErr {
+				t.Errorf("Test %d: Expected no error but found one for input %s. Error was: %v", i, test.input, err)
+			}
+
+			if !strings.Contains(err.Error(), test.expectedErrContent) {
+				t.Errorf("Test %d: Expected error to contain: %v, found error: %v, input: %s", i, test.expectedErrContent, err, test.input)
+			}
+		}
+	}
+}