Add generate sign function

signature.go

@@ -0,0 +1,75 @@
+package vonage
+
+import (
+	"crypto/hmac"
+	"crypto/md5"
+	"crypto/sha1"
+	"crypto/sha256"
+	"crypto/sha512"
+	"fmt"
+	"hash"
+	"sort"
+	"strings"
+)
+
+type SignMethod string
+
+const (
+	MD5HASH    SignMethod = "md5hash"
+	MD5HMAC    SignMethod = "md5hmac"
+	SHA1HMAC   SignMethod = "sha1hmac"
+	SHA256HMAC SignMethod = "sha256hmac"
+	SHA512HMAC SignMethod = "sha512hmac"
+)
+
+// GenerateSign generates the signature based on https://developer.vonage.com/concepts/guides/signing-messages
+// Params needs to contain all body and query parameters
+func GenerateSign(method SignMethod, secret string, params map[string]interface{}) ([]byte, error) {
+	if params == nil {
+		params = map[string]interface{}{}
+	}
+
+	delete(params, "sig")
+
+	keys := []string{}
+
+	for k := range params {
+		keys = append(keys, k)
+	}
+
+	sort.Strings(keys)
+
+	queryToSign := ""
+
+	for _, k := range keys {
+		queryToSign += "&" + k + "=" +
+			strings.NewReplacer("&", "_", "=", "_").Replace(fmt.Sprintf("%v", params[k]))
+	}
+
+	var h hash.Hash
+
+	switch method {
+	case MD5HASH:
+		queryToSign += secret
+
+		result := md5.Sum([]byte(queryToSign))
+
+		return result[:], nil
+	case MD5HMAC:
+		h = hmac.New(md5.New, []byte(secret))
+	case SHA1HMAC:
+		h = hmac.New(sha1.New, []byte(secret))
+	case SHA256HMAC:
+		h = hmac.New(sha256.New, []byte(secret))
+	case SHA512HMAC:
+		h = hmac.New(sha512.New, []byte(secret))
+	default:
+		return nil, fmt.Errorf("invalid method: %s", method)
+	}
+	_, err := h.Write([]byte(queryToSign))
+	if err != nil {
+		return nil, err
+	}
+
+	return h.Sum(nil), nil
+}

signature_test.go

@@ -0,0 +1,97 @@
+package vonage
+
+import (
+	"bytes"
+	"encoding/hex"
+	"testing"
+)
+
+func TestGenerate(t *testing.T) {
+	cases := []struct {
+		name           string
+		method         SignMethod
+		params         map[string]interface{}
+		secret         string
+		expectedResult string
+		errorExpected  bool
+	}{
+		{
+			name:          "invalid method",
+			method:        "random method",
+			errorExpected: true,
+		},
+		{
+			name:           "empty params",
+			method:         MD5HASH,
+			params:         map[string]interface{}{},
+			secret:         "secret",
+			expectedResult: "5ebe2294ecd0e0f08eab7690d2a6ee69",
+		},
+		{
+			name:   "only sig param",
+			method: MD5HASH,
+			params: map[string]interface{}{
+				"sig": "signature",
+			},
+			secret:         "secret",
+			expectedResult: "5ebe2294ecd0e0f08eab7690d2a6ee69",
+		},
+		{
+			name:   "custom param",
+			method: MD5HASH,
+			params: map[string]interface{}{
+				"from": "NEXMO",
+			},
+			secret:         "secret",
+			expectedResult: "2cdd20a2a0f7270545a98b3ccb87ba51",
+		},
+		{
+			name:           "empty params but with md5 hmac",
+			method:         MD5HMAC,
+			params:         map[string]interface{}{},
+			secret:         "secret",
+			expectedResult: "5c8db03f04cec0f43bcb060023914190",
+		},
+		{
+			name:           "empty params but with sha1 hmac",
+			method:         SHA1HMAC,
+			params:         map[string]interface{}{},
+			secret:         "secret",
+			expectedResult: "25af6174a0fcecc4d346680a72b7ce644b9a88e8",
+		},
+		{
+			name:           "empty params but with sha256 hmac",
+			method:         SHA256HMAC,
+			params:         map[string]interface{}{},
+			secret:         "secret",
+			expectedResult: "f9e66e179b6747ae54108f82f8ade8b3c25d76fd30afde6c395822c530196169",
+		},
+		{
+			name:           "empty params but with sha512 hmac",
+			method:         SHA512HMAC,
+			params:         map[string]interface{}{},
+			secret:         "secret",
+			expectedResult: "b0e9650c5faf9cd8ae02276671545424104589b3656731ec193b25d01b07561c27637c2d4d68389d6cf5007a8632c26ec89ba80a01c77a6cdd389ec28db43901",
+		},
+	}
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			result, err := GenerateSign(tc.method, tc.secret, tc.params)
+			if tc.errorExpected {
+				if err == nil {
+					t.Error("expected error but got nil")
+				}
+			} else {
+				if err != nil {
+					t.Error("expected no error but got one")
+				}
+
+				h, _ := hex.DecodeString(tc.expectedResult)
+
+				if !bytes.Equal(result, h) {
+					t.Error("invalid sign generated")
+				}
+			}
+		})
+	}
+}