internal/config: refactor option parsing

- authorize: build whitelist from policy's URLs instead of strings.
- internal/httputil: merged httputil and https package.
- internal/config: merged config and policy packages.
- internal/metrics: removed unused measure struct.
- proxy/clients: refactor Addr fields to be urls.
- proxy: remove unused extend deadline function.
- proxy: use handler middleware for reverse proxy leg.
- proxy: change the way websocket requests are made (route based).

General improvements
- omitted value from range in several cases where for loop could be simplified.
- added error checking to many tests.
- standardize url parsing.
- remove unnecessary return statements.

- proxy: add self-signed certificate support. #179
- proxy: add skip tls certificate verification. #179
- proxy: Refactor websocket support to be route based. #204

internal/cryptutil/encrypt.go

@@ -13,14 +13,32 @@ import (
 	"golang.org/x/crypto/chacha20poly1305"
 )
 
+const DefaultKeySize = 32
+
 // GenerateKey generates a random 32-byte key.
+//
 // Panics if source of randomness fails.
 func GenerateKey() []byte {
-	key := make([]byte, 32)
-	if _, err := rand.Read(key); err != nil {
+	return randomBytes(DefaultKeySize)
+}
+
+// GenerateRandomString returns base64 encoded securely generated random string
+// of a given set of bytes.
+//
+// Panics if source of randomness fails.
+func GenerateRandomString(c int) string {
+	return base64.StdEncoding.EncodeToString(randomBytes(c))
+}
+
+func randomBytes(c int) []byte {
+	if c < 0 {
+		c = DefaultKeySize
+	}
+	b := make([]byte, c)
+	if _, err := rand.Read(b); err != nil {
 		panic(err)
 	}
-	return key
+	return b
 }
 
 // Cipher provides methods to encrypt and decrypt values.