add MapClaims helper methods

Gopkg.toml

@@ -1,6 +0,0 @@
-[[constraint]]
-  name = "github.com/dgrijalva/jwt-go"
-  version = "^3.1.0"
-[[constraint]]
-  name = "github.com/go-chi/chi"
-  version = "^3.0.0"

go.mod

@@ -0,0 +1,3 @@
+module github.com/go-chi/jwtauth
+
+require github.com/dgrijalva/jwt-go v3.2.0+incompatible

go.sum

@@ -0,0 +1,2 @@
+github.com/dgrijalva/jwt-go v3.2.0+incompatible h1:7qlOGliEKZXTDg6OTjfoBKDXWrumCAMpl/TFQ4/5kLM=
+github.com/dgrijalva/jwt-go v3.2.0+incompatible/go.mod h1:E3ru+11k8xSBh+hMPgOLZmtrrCbhqsmaPHjLKYnJCaQ=

jwtauth.go

@@ -131,7 +131,7 @@ func VerifyRequest(ja *JWTAuth, r *http.Request, findTokenFns ...func(r *http.Re
 	return token, nil
 }
 
-func (ja *JWTAuth) Encode(claims jwt.MapClaims) (t *jwt.Token, tokenString string, err error) {
+func (ja *JWTAuth) Encode(claims jwt.Claims) (t *jwt.Token, tokenString string, err error) {
 	t = jwt.New(ja.signer)
 	t.Claims = claims
 	tokenString, err = t.SignedString(ja.signKey)
@@ -218,6 +218,26 @@ func ExpireIn(tm time.Duration) int64 {
 	return EpochNow() + int64(tm.Seconds())
 }
 
+// Set issued at ("iat") to specified time in the claims
+func SetIssuedAt(claims jwt.MapClaims, tm time.Time) {
+	claims["iat"] = tm.UTC().Unix()
+}
+
+// Set issued at ("iat") to present time in the claims
+func SetIssuedNow(claims jwt.MapClaims) {
+	claims["iat"] = EpochNow()
+}
+
+// Set expiry ("exp") in the claims
+func SetExpiry(claims jwt.MapClaims, tm time.Time) {
+	claims["exp"] = tm.UTC().Unix()
+}
+
+// Set expiry ("exp") in the claims to some duration from the present time
+func SetExpiryIn(claims jwt.MapClaims, tm time.Duration) {
+	claims["exp"] = ExpireIn(tm)
+}
+
 // TokenFromCookie tries to retreive the token string from a cookie named
 // "jwt".
 func TokenFromCookie(r *http.Request) string {