/
auth.go
200 lines (174 loc) · 4.53 KB
/
auth.go
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package http
import (
"context"
"crypto/sha256"
"fmt"
"net/url"
"strconv"
"strings"
"time"
"github.com/keys-pub/keys"
"github.com/keys-pub/keys/encoding"
"github.com/keys-pub/keys/tsutil"
"github.com/pkg/errors"
)
// Auth describes auth for an HTTP request.
type Auth struct {
KID keys.ID
Method string
URL *url.URL
Sig string
BytesToSign string
}
// Header is header value.
func (a Auth) Header() string {
return a.KID.String() + ":" + a.Sig
}
// NewAuth returns auth for an HTTP request.
// The url shouldn't have ? or &.
func NewAuth(method string, urs string, contentHash string, tm time.Time, key *keys.EdX25519Key) (*Auth, error) {
ur, err := authURL(urs, tm, keys.RandBytes(20))
if err != nil {
return nil, err
}
return newAuthWithURL(method, ur, contentHash, key)
}
// ContentHash returns base64 encoded sha256 hash.
func ContentHash(b []byte) string {
if len(b) == 0 {
return ""
}
h := sha256.Sum256(b)
return encoding.EncodeBase64(h[:])
}
func authURL(urs string, tm time.Time, nonce []byte) (*url.URL, error) {
if len(nonce) < 16 {
return nil, errors.Errorf("invalid nonce")
}
ur, err := url.Parse(urs)
if err != nil {
return nil, err
}
q := ur.Query()
ns := encoding.MustEncode(nonce, encoding.Base62)
q.Set("nonce", ns)
ts := tsutil.Millis(tm)
q.Set("ts", fmt.Sprintf("%d", ts))
ur.RawQuery = q.Encode()
return ur, nil
}
func newAuth(method string, urs string, contentHash string, tm time.Time, nonce []byte, key *keys.EdX25519Key) (*Auth, error) {
ur, err := authURL(urs, tm, nonce)
if err != nil {
return nil, err
}
return newAuthWithURL(method, ur, contentHash, key)
}
func newAuthWithURL(method string, ur *url.URL, contentHash string, key *keys.EdX25519Key) (*Auth, error) {
bytesToSign := method + "," + ur.String() + "," + contentHash
sb := key.SignDetached([]byte(bytesToSign))
sig := encoding.EncodeBase64(sb)
return &Auth{KID: key.ID(), Method: method, URL: ur, Sig: sig, BytesToSign: bytesToSign}, nil
}
// AuthRequest describes an auth request.
type AuthRequest struct {
Method string
URL string
ContentHash string
KID keys.ID
Auth string
Now time.Time
NonceCheck NonceCheck
}
// AuthResult is the result of an auth check.
type AuthResult struct {
KID keys.ID
URL *url.URL
Nonce string
Timestamp time.Time
}
// NonceCheck checks for nonce.
type NonceCheck func(ctx context.Context, nonce string) error
// Authorize checks request authorization.
// Nonce check should fail if there is a collision across different requests.
func Authorize(ctx context.Context, auth *AuthRequest) (*AuthResult, error) {
url, err := url.Parse(auth.URL)
if err != nil {
return nil, err
}
if url.String() != auth.URL {
return nil, errors.Errorf("invalid url parse")
}
// Parse nonce
nonce := url.Query().Get("nonce")
if nonce == "" {
return nil, errors.Errorf("nonce is missing")
}
nb, err := encoding.Decode(nonce, encoding.Base62)
if err != nil {
return nil, err
}
if len(nb) < 16 {
return nil, errors.Errorf("nonce is invalid length")
}
// Check timestamp
ts := url.Query().Get("ts")
if ts == "" {
return nil, errors.Errorf("timestamp (ts) is missing")
}
i, err := strconv.ParseInt(ts, 10, 64)
if err != nil {
return nil, err
}
tm := tsutil.ConvertMillis(i)
td := auth.Now.Sub(tm)
if td < 0 {
td = td * -1
}
if td > 30*time.Minute {
return nil, errors.Errorf("timestamp is invalid, diff %s", td)
}
fields := strings.Split(auth.Auth, ":")
if len(fields) != 2 {
return nil, errors.Errorf("too many fields")
}
hkid := fields[0]
hsig := fields[1]
akid, err := keys.ParseID(hkid)
if err != nil {
return nil, err
}
if auth.KID != "" && akid != auth.KID {
return nil, errors.Errorf("invalid kid")
}
spk, err := keys.StatementPublicKeyFromID(akid)
if err != nil {
return nil, errors.Errorf("not a valid sign public key")
}
sigBytes, err := encoding.Decode(hsig, encoding.Base64)
if err != nil {
return nil, err
}
bytesToSign := auth.Method + "," + url.String() + "," + auth.ContentHash
if err := spk.VerifyDetached(sigBytes, []byte(bytesToSign)); err != nil {
return nil, err
}
if auth.NonceCheck == nil {
return nil, errors.Errorf("no nonce check")
}
if err := auth.NonceCheck(ctx, nonce); err != nil {
return nil, err
}
return &AuthResult{
KID: akid,
URL: url,
Nonce: nonce,
Timestamp: tm,
}, nil
}
// if err := nonces.Set(ctx, nonce, "1"); err != nil {
// return nil, err
// }
// if err := nonces.Expire(ctx, nonce, time.Hour); err != nil {
// return nil, err
// }