Merge branch '6221-write-trash-list'

[arvados.git] / services / keepstore / perms.go

diff --git a/services/keepstore/perms.go b/services/keepstore/perms.go
index 143815576b33f077a89fead6e46efb795de20f9d..65160b1868913638e8315a266e0b3736ecfbe14c 100644 (file)
--- a/services/keepstore/perms.go
+++ b/services/keepstore/perms.go
@@ -80,23 +80,31 @@ func SignLocator(blob_locator string, api_token string, expiry time.Time) string
                "@" + timestamp_hex
 }
 
-// VerifySignature returns true if the signature on the signed_locator
-// can be verified using the given api_token.
-func VerifySignature(signed_locator string, api_token string) bool {
-       if re, err := regexp.Compile(`^([a-f0-9]{32}(\+[0-9]+)?).*\+A[[:xdigit:]]+@([[:xdigit:]]{8})`); err == nil {
-               if matches := re.FindStringSubmatch(signed_locator); matches != nil {
-                       blob_locator := matches[1]
-                       timestamp_hex := matches[3]
-                       if expire_ts, err := ParseHexTimestamp(timestamp_hex); err == nil {
-                               // Fail signatures with expired timestamps.
-                               if expire_ts.Before(time.Now()) {
-                                       return false
-                               }
-                               return signed_locator == SignLocator(blob_locator, api_token, expire_ts)
-                       }
-               }
+var signedLocatorRe = regexp.MustCompile(`^([[:xdigit:]]{32}).*\+A([[:xdigit:]]{40})@([[:xdigit:]]{8})`)
+
+// VerifySignature returns nil if the signature on the signed_locator
+// can be verified using the given api_token. Otherwise it returns
+// either ExpiredError (if the timestamp has expired, which is
+// something the client could have figured out independently) or
+// PermissionError.
+func VerifySignature(signed_locator string, api_token string) error {
+       matches := signedLocatorRe.FindStringSubmatch(signed_locator)
+       if matches == nil {
+               // Could not find a permission signature at all
+               return PermissionError
+       }
+       blob_hash := matches[1]
+       sig_hex := matches[2]
+       exp_hex := matches[3]
+       if exp_time, err := ParseHexTimestamp(exp_hex); err != nil {
+               return PermissionError
+       } else if exp_time.Before(time.Now()) {
+               return ExpiredError
+       }
+       if sig_hex != MakePermSignature(blob_hash, api_token, exp_hex) {
+               return PermissionError
        }
-       return false
+       return nil
 }
 
 func ParseHexTimestamp(timestamp_hex string) (ts time.Time, err error) {