path: root/p2p/netutil/error_test.go

// Copyright 2016 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

package netutil

import (
    "net"
    "testing"
    "time"
)

// This test checks that isPacketTooBig correctly identifies
// errors that result from receiving a UDP packet larger
// than the supplied receive buffer.
func TestIsPacketTooBig(t *testing.T) {
    listener, err := net.ListenPacket("udp", "127.0.0.1:0")
    if err != nil {
        t.Fatal(err)
    }
    defer listener.Close()
    sender, err := net.Dial("udp", listener.LocalAddr().String())
    if err != nil {
        t.Fatal(err)
    }
    defer sender.Close()

    sendN := 1800
    recvN := 300
    for i := 0; i < 20; i++ {
        go func() {
            buf := make([]byte, sendN)
            for i := range buf {
                buf[i] = byte(i)
            }
            sender.Write(buf)
        }()

        buf := make([]byte, recvN)
        listener.SetDeadline(time.Now().Add(1 * time.Second))
        n, _, err := listener.ReadFrom(buf)
        if err != nil {
            if nerr, ok := err.(net.Error); ok && nerr.Timeout() {
                continue
            }
            if !isPacketTooBig(err) {
                t.Fatalf("unexpected read error: %v", err)
            }
            continue
        }
        if n != recvN {
            t.Fatalf("short read: %d, want %d", n, recvN)
        }
        for i := range buf {
            if buf[i] != byte(i) {
                t.Fatalf("error in pattern")
                break
            }
        }
    }
}