henderjon/jwt

package jwt

import (
    "time"

    "github.com/google/uuid"
)

// Header is a typical JWT header
type Header struct {
    Type      string `json:"typ,omitempty"`
    Algorithm string `json:"alg,omitempty"` //  Algorithm
}

// NewHeader returns a basic header given the algorithm
func NewHeader(alg string) Header {
    return Header{
        Type:      "JWT",
        Algorithm: alg,
    }
}

// RegisteredClaims implements Claimer and represents the standard registered claims of a JWT
type RegisteredClaims struct {
    Audience       string `json:"aud,omitempty"` // (Audience) Claim
    Issuer         string `json:"iss,omitempty"` // (Issuer) Claim
    JWTID          string `json:"jti,omitempty"` // (JWT ID) Claim
    IssuedAt       int64  `json:"iat,omitempty"` // (Issued At) Claim
    ExpirationTime int64  `json:"exp,omitempty"` // (Expiration Time) Claim
    Subject        string `json:"sub,omitempty"` // (Subject) Claim
    NotBefore      int64  `json:"nbf,omitempty"` // (Not Before) Claim
}

// NewRegisteredClaims gives you a basic set of claims based on the given subject and expiration
func NewRegisteredClaims(exp time.Time) RegisteredClaims {
    return RegisteredClaims{
        ExpirationTime: exp.UTC().Unix(),
        JWTID:          uuid.New().String(),
    }
}

func (c *RegisteredClaims) TTL(t time.Duration) {
    c.ExpirationTime = time.Now().Add(t).UTC().Unix()
}

// NotActive checks to see if the claims' `nbf` field is less than the given time
func (c *RegisteredClaims) NotActive(t time.Time) bool {
    if c.NotBefore == 0 {
        return false
    }
    return c.NotBefore >= t.UTC().Unix()
}

// IsExpired checks to see if the claims' `exp` field is less than the given time
func (c *RegisteredClaims) IsExpired(t time.Time) bool {
    if c.ExpirationTime == 0 {
        return false
    }
    return c.ExpirationTime <= t.UTC().Unix()
}

// Valid implements Claimer and validates the current claim `NotActive` & `IsExpired` against time.Now()
func (c *RegisteredClaims) Valid() bool {
    t := time.Now().UTC()
    return !c.NotActive(t) && !c.IsExpired(t)
}