Merge branch 'master' into 7241-azure-blob-volume

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

diff --git a/services/keepstore/perms.go b/services/keepstore/perms.go
index 1048f53130315525da0a80c1214207a9eb101cd5..5579238112b65ed0747ec33e82e582e580e74e6d 100644 (file)
--- a/services/keepstore/perms.go
+++ b/services/keepstore/perms.go
@@ -51,58 +51,66 @@ import (
 var PermissionSecret []byte
 
 // MakePermSignature returns a string representing the signed permission
-// hint for the blob identified by blob_hash, api_token and expiration timestamp.
-func MakePermSignature(blob_hash string, api_token string, expiry string) string {
+// hint for the blob identified by blobHash, apiToken and expiration timestamp.
+func MakePermSignature(blobHash string, apiToken string, expiry string) string {
        hmac := hmac.New(sha1.New, PermissionSecret)
-       hmac.Write([]byte(blob_hash))
+       hmac.Write([]byte(blobHash))
        hmac.Write([]byte("@"))
-       hmac.Write([]byte(api_token))
+       hmac.Write([]byte(apiToken))
        hmac.Write([]byte("@"))
        hmac.Write([]byte(expiry))
        digest := hmac.Sum(nil)
        return fmt.Sprintf("%x", digest)
 }
 
-// SignLocator takes a blob_locator, an api_token and an expiry time, and
+// SignLocator takes a blobLocator, an apiToken and an expiry time, and
 // returns a signed locator string.
-func SignLocator(blob_locator string, api_token string, expiry time.Time) string {
+func SignLocator(blobLocator string, apiToken string, expiry time.Time) string {
        // If no permission secret or API token is available,
        // return an unsigned locator.
-       if PermissionSecret == nil || api_token == "" {
-               return blob_locator
+       if PermissionSecret == nil || apiToken == "" {
+               return blobLocator
        }
        // Extract the hash from the blob locator, omitting any size hint that may be present.
-       blob_hash := strings.Split(blob_locator, "+")[0]
+       blobHash := strings.Split(blobLocator, "+")[0]
        // Return the signed locator string.
-       timestamp_hex := fmt.Sprintf("%08x", expiry.Unix())
-       return blob_locator +
-               "+A" + MakePermSignature(blob_hash, api_token, timestamp_hex) +
-               "@" + timestamp_hex
+       timestampHex := fmt.Sprintf("%08x", expiry.Unix())
+       return blobLocator +
+               "+A" + MakePermSignature(blobHash, apiToken, timestampHex) +
+               "@" + timestampHex
 }
 
 var signedLocatorRe = regexp.MustCompile(`^([[:xdigit:]]{32}).*\+A([[:xdigit:]]{40})@([[:xdigit:]]{8})`)
 
-// 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 {
-       matches := signedLocatorRe.FindStringSubmatch(signed_locator)
+// VerifySignature returns nil if the signature on the signedLocator
+// can be verified using the given apiToken. Otherwise it returns
+// either ExpiredError (if the timestamp has expired, which is
+// something the client could have figured out independently) or
+// PermissionError.
+func VerifySignature(signedLocator string, apiToken string) error {
+       matches := signedLocatorRe.FindStringSubmatch(signedLocator)
        if matches == nil {
                // Could not find a permission signature at all
-               return false
+               return PermissionError
        }
-       blob_hash := matches[1]
-       sig_hex := matches[2]
-       exp_hex := matches[3]
-       if exp_time, err := ParseHexTimestamp(exp_hex); err != nil || exp_time.Before(time.Now()) {
-               // Signature is expired, or timestamp is unparseable
-               return false
+       blobHash := matches[1]
+       sigHex := matches[2]
+       expHex := matches[3]
+       if expTime, err := ParseHexTimestamp(expHex); err != nil {
+               return PermissionError
+       } else if expTime.Before(time.Now()) {
+               return ExpiredError
        }
-       return sig_hex == MakePermSignature(blob_hash, api_token, exp_hex)
+       if sigHex != MakePermSignature(blobHash, apiToken, expHex) {
+               return PermissionError
+       }
+       return nil
 }
 
-func ParseHexTimestamp(timestamp_hex string) (ts time.Time, err error) {
-       if ts_int, e := strconv.ParseInt(timestamp_hex, 16, 0); e == nil {
-               ts = time.Unix(ts_int, 0)
+// ParseHexTimestamp parses timestamp
+func ParseHexTimestamp(timestampHex string) (ts time.Time, err error) {
+       if tsInt, e := strconv.ParseInt(timestampHex, 16, 0); e == nil {
+               ts = time.Unix(tsInt, 0)
        } else {
                err = e
        }