127 lines
3.8 KiB
Go
127 lines
3.8 KiB
Go
package jwt
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import (
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"encoding/base64"
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"encoding/json"
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"net/http"
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"strings"
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"time"
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)
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// TimeFunc provides the current time when parsing token to validate "exp" claim (expiration time).
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// You can override it to use another time value. This is useful for testing or if your
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// server uses a different time zone than your tokens.
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var TimeFunc = time.Now
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// Parse methods use this callback function to supply
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// the key for verification. The function receives the parsed,
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// but unverified Token. This allows you to use propries in the
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// Header of the token (such as `kid`) to identify which key to use.
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type Keyfunc func(*Token) (interface{}, error)
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// A JWT Token. Different fields will be used depending on whether you're
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// creating or parsing/verifying a token.
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type Token struct {
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Raw string // The raw token. Populated when you Parse a token
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Method SigningMethod // The signing method used or to be used
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Header map[string]interface{} // The first segment of the token
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Claims map[string]interface{} // The second segment of the token
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Signature string // The third segment of the token. Populated when you Parse a token
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Valid bool // Is the token valid? Populated when you Parse/Verify a token
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}
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// Create a new Token. Takes a signing method
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func New(method SigningMethod) *Token {
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return &Token{
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Header: map[string]interface{}{
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"typ": "JWT",
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"alg": method.Alg(),
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},
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Claims: make(map[string]interface{}),
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Method: method,
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}
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}
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// Get the complete, signed token
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func (t *Token) SignedString(key interface{}) (string, error) {
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var sig, sstr string
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var err error
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if sstr, err = t.SigningString(); err != nil {
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return "", err
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}
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if sig, err = t.Method.Sign(sstr, key); err != nil {
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return "", err
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}
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return strings.Join([]string{sstr, sig}, "."), nil
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}
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// Generate the signing string. This is the
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// most expensive part of the whole deal. Unless you
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// need this for something special, just go straight for
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// the SignedString.
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func (t *Token) SigningString() (string, error) {
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var err error
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parts := make([]string, 2)
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for i, _ := range parts {
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var source map[string]interface{}
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if i == 0 {
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source = t.Header
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} else {
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source = t.Claims
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}
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var jsonValue []byte
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if jsonValue, err = json.Marshal(source); err != nil {
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return "", err
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}
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parts[i] = EncodeSegment(jsonValue)
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}
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return strings.Join(parts, "."), nil
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}
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// Parse, validate, and return a token.
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// keyFunc will receive the parsed token and should return the key for validating.
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// If everything is kosher, err will be nil
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func Parse(tokenString string, keyFunc Keyfunc) (*Token, error) {
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return new(Parser).Parse(tokenString, keyFunc)
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}
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// Try to find the token in an http.Request.
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// This method will call ParseMultipartForm if there's no token in the header.
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// Currently, it looks in the Authorization header as well as
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// looking for an 'access_token' request parameter in req.Form.
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func ParseFromRequest(req *http.Request, keyFunc Keyfunc) (token *Token, err error) {
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// Look for an Authorization header
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if ah := req.Header.Get("Authorization"); ah != "" {
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// Should be a bearer token
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if len(ah) > 6 && strings.ToUpper(ah[0:7]) == "BEARER " {
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return Parse(ah[7:], keyFunc)
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}
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}
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// Look for "access_token" parameter
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req.ParseMultipartForm(10e6)
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if tokStr := req.Form.Get("access_token"); tokStr != "" {
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return Parse(tokStr, keyFunc)
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}
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return nil, ErrNoTokenInRequest
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}
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// Encode JWT specific base64url encoding with padding stripped
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func EncodeSegment(seg []byte) string {
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return strings.TrimRight(base64.URLEncoding.EncodeToString(seg), "=")
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}
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// Decode JWT specific base64url encoding with padding stripped
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func DecodeSegment(seg string) ([]byte, error) {
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if l := len(seg) % 4; l > 0 {
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seg += strings.Repeat("=", 4-l)
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}
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return base64.URLEncoding.DecodeString(seg)
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}
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