[tor-commits] [meek/webextension] Fix the overlong message checks.

[dcf at torproject.org]

commit de03366fbe1f23cbb21d41aec8f4913f189ecb8b
Author: David Fifield <david at bamsoftware.com>
Date:   Fri Feb 22 18:58:50 2019 -0700

    Fix the overlong message checks.
    
    It'll never exceed math.MaxUint32 if you convert it to uint32 first... I
    didn't notice what nonsense this was until I saw the commit email.
    
    len returns int, which is specified to be either 32 or 64 bits, so it
    will never be truncated when coverting to uint64.
    https://golang.org/ref/spec#Numeric_types
---
 webextension/native/main.go | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/webextension/native/main.go b/webextension/native/main.go
index 10a2b90..3f4ec3a 100644
--- a/webextension/native/main.go
+++ b/webextension/native/main.go
@@ -139,7 +139,7 @@ func writeResponseSpec(w io.Writer, spec *responseSpec) error {
 	}
 
 	length := len(encodedSpec)
-	if uint32(length) > math.MaxUint32 {
+	if uint64(length) > math.MaxUint32 {
 		return fmt.Errorf("response spec is too long to represent: %d", length)
 	}
 	err = binary.Write(w, binary.BigEndian, uint32(length))
@@ -178,7 +178,7 @@ func recvWebExtensionMessage(r io.Reader) ([]byte, error) {
 // https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/Native_messaging#App_side
 func sendWebExtensionMessage(w io.Writer, message []byte) error {
 	length := len(message)
-	if uint32(length) > math.MaxUint32 {
+	if uint64(length) > math.MaxUint32 {
 		return fmt.Errorf("WebExtension message is too long to represent: %d", length)
 	}
 	err := binary.Write(w, NativeEndian, uint32(length))