add auth package to hash requests

auth/auth.go

@@ -0,0 +1,57 @@
+package auth
+
+import (
+	"crypto/rand"
+	"crypto/sha1"
+	"encoding/hex"
+	"fmt"
+	"math/big"
+	"strconv"
+	"strings"
+	"time"
+)
+
+var (
+	saltChars      = "0123456789ABCDEFGHIJKLMNOPQRTSUVWXYZabcdefghijklmnopqrstuvwxyz"
+	baseUrl        = "https://api.nearlyfreespeech.net"
+	authHeaderName = "X-NFSN-Authentication"
+	maxSalt        big.Int
+)
+
+func init() {
+	maxSalt.SetInt64(int64(len(saltChars)))
+}
+
+func Salt() (string, error) {
+	salt := make([]string, 16)
+	for i := 0; i < 16; i++ {
+		rand_index, err := rand.Int(rand.Reader, &maxSalt)
+		if err != nil {
+			return "", err
+		}
+
+		salt[i] = string(saltChars[rand_index.Int64()])
+	}
+
+	return strings.Join(salt, ""), nil
+}
+
+func Timestamp() string {
+	return strconv.FormatInt(time.Now().Unix(), 10)
+}
+
+func ComputeHash(data string) string {
+	result := sha1.Sum([]byte(data))
+	return hex.EncodeToString(result[:])
+}
+
+func GetAuthHeader(login string, apiKey string, url string, body string) (string, error) {
+	timestamp := Timestamp()
+	salt, err := Salt()
+	if err != nil {
+		return "", err
+	}
+	bodyHash := ComputeHash(body)
+	hash := ComputeHash(fmt.Sprintf("%s;%s;%s;%s;%s;%s", login, timestamp, salt, apiKey, url, bodyHash))
+	return hash, nil
+}