// SetReadLimit sets the maximum size for a message read from the peer. If a
// message exceeds the limit, the connection sends a close message to the peer
// and returns ErrReadLimit to the application.
func (c *Conn) SetReadLimit(limit int64) {
c.readLimit = limit
}
What is the unit of limit? KB? MB ?
Based on the sources of gorilla/websocket, it's in bytes.
const readLimit = 512
message := make([]byte, readLimit+1)
.....
rc.SetReadLimit(readLimit)
Here is the full unit test:
func TestReadLimit(t *testing.T) {
const readLimit = 512
message := make([]byte, readLimit+1)
var b1, b2 bytes.Buffer
wc := newConn(&fakeNetConn{Writer: &b1}, false, 1024, readLimit-2, nil, nil, nil)
rc := newTestConn(&b1, &b2, true)
rc.SetReadLimit(readLimit)
// Send message at the limit with interleaved pong.
w, _ := wc.NextWriter(BinaryMessage)
w.Write(message[:readLimit-1])
wc.WriteControl(PongMessage, []byte("this is a pong"), time.Now().Add(10*time.Second))
w.Write(message[:1])
w.Close()
// Send message larger than the limit.
wc.WriteMessage(BinaryMessage, message[:readLimit+1])
op, _, err := rc.NextReader()
if op != BinaryMessage || err != nil {
t.Fatalf("1: NextReader() returned %d, %v", op, err)
}
op, r, err := rc.NextReader()
if op != BinaryMessage || err != nil {
t.Fatalf("2: NextReader() returned %d, %v", op, err)
}
_, err = io.Copy(ioutil.Discard, r)
if err != ErrReadLimit {
t.Fatalf("io.Copy() returned %v", err)
}
}
This does not seem to be well-documented indeed, but according to the corresponding test it is in bytes. I'd assume that to be a default unit anyway.
The relevant test code:
// Send message at the limit with interleaved pong.
w, _ := wc.NextWriter(BinaryMessage)
w.Write(message[:readLimit-1])
wc.WriteControl(PongMessage, []byte("this is a pong"), time.Now().Add(10*time.Second))
w.Write(message[:1])
w.Close()
// Send message larger than the limit.
wc.WriteMessage(BinaryMessage, message[:readLimit+1])
// ...
_, err = io.Copy(ioutil.Discard, r)
if err != ErrReadLimit {
t.Fatalf("io.Copy() returned %v", err)
}
