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lib/protocol: Hello message length is an int16

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It used to be an int32, but that's unnecessary and the spec now says
int16. Also relaxes the size requirement to that which fits in a signed
int16 instead of limiting to 1024 bytes, to allow for future growth.

As reported in
https://forum.syncthing.net/t/difference-between-documented-and-implemented-protocol/7798

GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/3406
This commit is contained in:
Jakob Borg 2016-07-17 21:41:20 +00:00
parent 3176629410
commit 7b7e35d339
2 changed files with 19 additions and 9 deletions
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24
lib/protocol/hello.go
View File

@ -56,16 +56,19 @@ func IsVersionMismatch(err error) bool {
}
func readHello(c io.Reader) (HelloResult, error) {
header := make([]byte, 8)
header := make([]byte, 4)
if _, err := io.ReadFull(c, header); err != nil {
return HelloResult{}, err
}
switch binary.BigEndian.Uint32(header[:4]) {
switch binary.BigEndian.Uint32(header) {
case HelloMessageMagic:
// This is a v0.14 Hello message in proto format
msgSize := binary.BigEndian.Uint32(header[4:])
if msgSize > 1024 {
if _, err := io.ReadFull(c, header[:2]); err != nil {
return HelloResult{}, err
}
msgSize := binary.BigEndian.Uint16(header[:2])
if msgSize > 32767 {
return HelloResult{}, fmt.Errorf("hello message too big")
}
buf := make([]byte, msgSize)
@ -86,7 +89,10 @@ func readHello(c io.Reader) (HelloResult, error) {
case Version13HelloMagic:
// This is a v0.13 Hello message in XDR format
msgSize := binary.BigEndian.Uint32(header[4:])
if _, err := io.ReadFull(c, header[:4]); err != nil {
return HelloResult{}, err
}
msgSize := binary.BigEndian.Uint32(header[:4])
if msgSize > 1024 {
return HelloResult{}, fmt.Errorf("hello message too big")
}
@ -120,10 +126,14 @@ func writeHello(c io.Writer, h HelloIntf) error {
if err != nil {
return err
}
if len(msg) > 32767 {
// The header length must be a positive signed int16
panic("bug: attempting to serialize too large hello message")
}
header := make([]byte, 8)
header := make([]byte, 6)
binary.BigEndian.PutUint32(header[:4], h.Magic())
binary.BigEndian.PutUint32(header[4:], uint32(len(msg)))
binary.BigEndian.PutUint16(header[4:], uint16(len(msg)))
_, err = c.Write(append(header, msg...))
return err

4
lib/protocol/hello_test.go
View File

@ -26,9 +26,9 @@ func TestVersion14Hello(t *testing.T) {
t.Fatal(err)
}
hdrBuf := make([]byte, 8)
hdrBuf := make([]byte, 6)
binary.BigEndian.PutUint32(hdrBuf, HelloMessageMagic)
binary.BigEndian.PutUint32(hdrBuf[4:], uint32(len(msgBuf)))
binary.BigEndian.PutUint16(hdrBuf[4:], uint16(len(msgBuf)))
outBuf := new(bytes.Buffer)
outBuf.Write(hdrBuf)