package token import ( "fmt" "net/http" "github.com/dgrijalva/jwt-go" ) type SecretFunc func(*Token) (string, error) const ( UserToken = "user" SessToken = "sess" HookToken = "hook" CsrfToken = "csrf" ) // Default algorithm used to sign JWT tokens. const SignerAlgo = "HS256" type Token struct { Kind string Text string } func Parse(raw string, fn SecretFunc) (*Token, error) { token := &Token{} parsed, err := jwt.Parse(raw, keyFunc(token, fn)) if err != nil { return nil, err } else if !parsed.Valid { return nil, jwt.ValidationError{} } return token, nil } func ParseRequest(r *http.Request, fn SecretFunc) (*Token, error) { var token = r.Header.Get("Authorization") // first we attempt to get the token from the // authorization header. if len(token) != 0 { token = r.Header.Get("Authorization") fmt.Sscanf(token, "Bearer %s", &token) return Parse(token, fn) } // then we attempt to get the token from the // access_token url query parameter token = r.FormValue("access_token") if len(token) != 0 { return Parse(token, fn) } // and finally we attemt to get the token from // the user session cookie cookie, err := r.Cookie("user_sess") if err != nil { return nil, err } return Parse(cookie.Value, fn) } func CheckCsrf(r *http.Request, fn SecretFunc) error { // get and options requests are always // enabled, without CSRF checks. switch r.Method { case "GET", "OPTIONS": return nil } // parse the raw CSRF token value and validate raw := r.Header.Get("X-CSRF-TOKEN") _, err := Parse(raw, fn) return err } func New(kind, text string) *Token { return &Token{Kind: kind, Text: text} } // Sign signs the token using the given secret hash // and returns the string value. func (t *Token) Sign(secret string) (string, error) { return t.SignExpires(secret, 0) } // Sign signs the token using the given secret hash // with an expiration date. func (t *Token) SignExpires(secret string, exp int64) (string, error) { token := jwt.New(jwt.SigningMethodHS256) token.Claims["type"] = t.Kind token.Claims["text"] = t.Text if exp > 0 { token.Claims["exp"] = float64(exp) } return token.SignedString([]byte(secret)) } func keyFunc(token *Token, fn SecretFunc) jwt.Keyfunc { return func(t *jwt.Token) (interface{}, error) { // validate the correct algorithm is being used if t.Method.Alg() != SignerAlgo { return nil, jwt.ErrSignatureInvalid } // extract the token kind and cast to // the expected type. kindv, ok := t.Claims["type"] if !ok { return nil, jwt.ValidationError{} } token.Kind, _ = kindv.(string) // extract the token value and cast to // exepected type. textv, ok := t.Claims["text"] if !ok { return nil, jwt.ValidationError{} } token.Text, _ = textv.(string) // invoke the callback function to retrieve // the secret key used to verify secret, err := fn(token) return []byte(secret), err } }