mirror of
https://github.com/go-gitea/gitea.git
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183 lines
5.8 KiB
Go
183 lines
5.8 KiB
Go
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// Copyright 2014 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package jws provides a partial implementation
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// of JSON Web Signature encoding and decoding.
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// It exists to support the golang.org/x/oauth2 package.
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//
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// See RFC 7515.
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//
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// Deprecated: this package is not intended for public use and might be
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// removed in the future. It exists for internal use only.
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// Please switch to another JWS package or copy this package into your own
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// source tree.
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package jws // import "golang.org/x/oauth2/jws"
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import (
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"bytes"
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"crypto"
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"crypto/rand"
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"crypto/rsa"
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"crypto/sha256"
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"encoding/base64"
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"encoding/json"
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"errors"
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"fmt"
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"strings"
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"time"
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)
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// ClaimSet contains information about the JWT signature including the
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// permissions being requested (scopes), the target of the token, the issuer,
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// the time the token was issued, and the lifetime of the token.
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type ClaimSet struct {
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Iss string `json:"iss"` // email address of the client_id of the application making the access token request
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Scope string `json:"scope,omitempty"` // space-delimited list of the permissions the application requests
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Aud string `json:"aud"` // descriptor of the intended target of the assertion (Optional).
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Exp int64 `json:"exp"` // the expiration time of the assertion (seconds since Unix epoch)
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Iat int64 `json:"iat"` // the time the assertion was issued (seconds since Unix epoch)
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Typ string `json:"typ,omitempty"` // token type (Optional).
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// Email for which the application is requesting delegated access (Optional).
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Sub string `json:"sub,omitempty"`
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// The old name of Sub. Client keeps setting Prn to be
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// complaint with legacy OAuth 2.0 providers. (Optional)
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Prn string `json:"prn,omitempty"`
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// See http://tools.ietf.org/html/draft-jones-json-web-token-10#section-4.3
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// This array is marshalled using custom code (see (c *ClaimSet) encode()).
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PrivateClaims map[string]interface{} `json:"-"`
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}
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func (c *ClaimSet) encode() (string, error) {
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// Reverting time back for machines whose time is not perfectly in sync.
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// If client machine's time is in the future according
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// to Google servers, an access token will not be issued.
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now := time.Now().Add(-10 * time.Second)
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if c.Iat == 0 {
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c.Iat = now.Unix()
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}
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if c.Exp == 0 {
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c.Exp = now.Add(time.Hour).Unix()
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}
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if c.Exp < c.Iat {
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return "", fmt.Errorf("jws: invalid Exp = %v; must be later than Iat = %v", c.Exp, c.Iat)
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}
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b, err := json.Marshal(c)
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if err != nil {
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return "", err
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}
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if len(c.PrivateClaims) == 0 {
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return base64.RawURLEncoding.EncodeToString(b), nil
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}
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// Marshal private claim set and then append it to b.
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prv, err := json.Marshal(c.PrivateClaims)
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if err != nil {
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return "", fmt.Errorf("jws: invalid map of private claims %v", c.PrivateClaims)
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}
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// Concatenate public and private claim JSON objects.
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if !bytes.HasSuffix(b, []byte{'}'}) {
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return "", fmt.Errorf("jws: invalid JSON %s", b)
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}
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if !bytes.HasPrefix(prv, []byte{'{'}) {
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return "", fmt.Errorf("jws: invalid JSON %s", prv)
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}
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b[len(b)-1] = ',' // Replace closing curly brace with a comma.
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b = append(b, prv[1:]...) // Append private claims.
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return base64.RawURLEncoding.EncodeToString(b), nil
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}
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// Header represents the header for the signed JWS payloads.
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type Header struct {
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// The algorithm used for signature.
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Algorithm string `json:"alg"`
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// Represents the token type.
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Typ string `json:"typ"`
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// The optional hint of which key is being used.
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KeyID string `json:"kid,omitempty"`
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}
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func (h *Header) encode() (string, error) {
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b, err := json.Marshal(h)
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if err != nil {
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return "", err
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}
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return base64.RawURLEncoding.EncodeToString(b), nil
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}
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// Decode decodes a claim set from a JWS payload.
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func Decode(payload string) (*ClaimSet, error) {
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// decode returned id token to get expiry
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s := strings.Split(payload, ".")
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if len(s) < 2 {
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// TODO(jbd): Provide more context about the error.
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return nil, errors.New("jws: invalid token received")
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}
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decoded, err := base64.RawURLEncoding.DecodeString(s[1])
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if err != nil {
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return nil, err
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}
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c := &ClaimSet{}
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err = json.NewDecoder(bytes.NewBuffer(decoded)).Decode(c)
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return c, err
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}
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// Signer returns a signature for the given data.
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type Signer func(data []byte) (sig []byte, err error)
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// EncodeWithSigner encodes a header and claim set with the provided signer.
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func EncodeWithSigner(header *Header, c *ClaimSet, sg Signer) (string, error) {
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head, err := header.encode()
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if err != nil {
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return "", err
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}
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cs, err := c.encode()
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if err != nil {
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return "", err
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}
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ss := fmt.Sprintf("%s.%s", head, cs)
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sig, err := sg([]byte(ss))
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if err != nil {
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return "", err
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}
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return fmt.Sprintf("%s.%s", ss, base64.RawURLEncoding.EncodeToString(sig)), nil
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}
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// Encode encodes a signed JWS with provided header and claim set.
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// This invokes EncodeWithSigner using crypto/rsa.SignPKCS1v15 with the given RSA private key.
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func Encode(header *Header, c *ClaimSet, key *rsa.PrivateKey) (string, error) {
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sg := func(data []byte) (sig []byte, err error) {
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h := sha256.New()
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h.Write(data)
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return rsa.SignPKCS1v15(rand.Reader, key, crypto.SHA256, h.Sum(nil))
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}
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return EncodeWithSigner(header, c, sg)
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}
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// Verify tests whether the provided JWT token's signature was produced by the private key
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// associated with the supplied public key.
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func Verify(token string, key *rsa.PublicKey) error {
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parts := strings.Split(token, ".")
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if len(parts) != 3 {
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return errors.New("jws: invalid token received, token must have 3 parts")
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}
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signedContent := parts[0] + "." + parts[1]
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signatureString, err := base64.RawURLEncoding.DecodeString(parts[2])
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if err != nil {
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return err
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}
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h := sha256.New()
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h.Write([]byte(signedContent))
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return rsa.VerifyPKCS1v15(key, crypto.SHA256, h.Sum(nil), []byte(signatureString))
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}
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