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

4
lib/protocol/hello_test.go
View File

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