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package p2p
import (
"net"
"sync"
"time"
cmn "github.com/tendermint/tmlibs/common"
)
const (
// FuzzModeDrop is a mode in which we randomly drop reads/writes, connections or sleep
FuzzModeDrop = iota
// FuzzModeDelay is a mode in which we randomly sleep
FuzzModeDelay
)
// FuzzedConnection wraps any net.Conn and depending on the mode either delays
// reads/writes or randomly drops reads/writes/connections.
type FuzzedConnection struct {
conn net.Conn
mtx sync.Mutex
start <-chan time.Time
active bool
config *FuzzConnConfig
}
// FuzzConnConfig is a FuzzedConnection configuration.
type FuzzConnConfig struct {
Mode int
MaxDelay time.Duration
ProbDropRW float64
ProbDropConn float64
ProbSleep float64
}
// DefaultFuzzConnConfig returns the default config.
func DefaultFuzzConnConfig() *FuzzConnConfig {
return &FuzzConnConfig{
Mode: FuzzModeDrop,
MaxDelay: 3 * time.Second,
ProbDropRW: 0.2,
ProbDropConn: 0.00,
ProbSleep: 0.00,
}
}
// FuzzConn creates a new FuzzedConnection. Fuzzing starts immediately.
func FuzzConn(conn net.Conn) net.Conn {
return FuzzConnFromConfig(conn, DefaultFuzzConnConfig())
}
// FuzzConnFromConfig creates a new FuzzedConnection from a config. Fuzzing
// starts immediately.
func FuzzConnFromConfig(conn net.Conn, config *FuzzConnConfig) net.Conn {
return &FuzzedConnection{
conn: conn,
start: make(<-chan time.Time),
active: true,
config: config,
}
}
// FuzzConnAfter creates a new FuzzedConnection. Fuzzing starts when the
// duration elapses.
func FuzzConnAfter(conn net.Conn, d time.Duration) net.Conn {
return FuzzConnAfterFromConfig(conn, d, DefaultFuzzConnConfig())
}
// FuzzConnAfterFromConfig creates a new FuzzedConnection from a config.
// Fuzzing starts when the duration elapses.
func FuzzConnAfterFromConfig(conn net.Conn, d time.Duration, config *FuzzConnConfig) net.Conn {
return &FuzzedConnection{
conn: conn,
start: time.After(d),
active: false,
config: config,
}
}
// Config returns the connection's config.
func (fc *FuzzedConnection) Config() *FuzzConnConfig {
return fc.config
}
// Read implements net.Conn.
func (fc *FuzzedConnection) Read(data []byte) (n int, err error) {
if fc.fuzz() {
return 0, nil
}
return fc.conn.Read(data)
}
// Write implements net.Conn.
func (fc *FuzzedConnection) Write(data []byte) (n int, err error) {
if fc.fuzz() {
return 0, nil
}
return fc.conn.Write(data)
}
// Close implements net.Conn.
func (fc *FuzzedConnection) Close() error { return fc.conn.Close() }
// LocalAddr implements net.Conn.
func (fc *FuzzedConnection) LocalAddr() net.Addr { return fc.conn.LocalAddr() }
// RemoteAddr implements net.Conn.
func (fc *FuzzedConnection) RemoteAddr() net.Addr { return fc.conn.RemoteAddr() }
// SetDeadline implements net.Conn.
func (fc *FuzzedConnection) SetDeadline(t time.Time) error { return fc.conn.SetDeadline(t) }
// SetReadDeadline implements net.Conn.
func (fc *FuzzedConnection) SetReadDeadline(t time.Time) error {
return fc.conn.SetReadDeadline(t)
}
// SetWriteDeadline implements net.Conn.
func (fc *FuzzedConnection) SetWriteDeadline(t time.Time) error {
return fc.conn.SetWriteDeadline(t)
}
func (fc *FuzzedConnection) randomDuration() time.Duration {
maxDelayMillis := int(fc.config.MaxDelay.Nanoseconds() / 1000)
return time.Millisecond * time.Duration(cmn.RandInt()%maxDelayMillis) // nolint: gas
}
// implements the fuzz (delay, kill conn)
// and returns whether or not the read/write should be ignored
func (fc *FuzzedConnection) fuzz() bool {
if !fc.shouldFuzz() {
return false
}
switch fc.config.Mode {
case FuzzModeDrop:
// randomly drop the r/w, drop the conn, or sleep
r := cmn.RandFloat64()
if r <= fc.config.ProbDropRW {
return true
} else if r < fc.config.ProbDropRW+fc.config.ProbDropConn {
// XXX: can't this fail because machine precision?
// XXX: do we need an error?
fc.Close() // nolint: errcheck, gas
return true
} else if r < fc.config.ProbDropRW+fc.config.ProbDropConn+fc.config.ProbSleep {
time.Sleep(fc.randomDuration())
}
case FuzzModeDelay:
// sleep a bit
time.Sleep(fc.randomDuration())
}
return false
}
func (fc *FuzzedConnection) shouldFuzz() bool {
if fc.active {
return true
}
fc.mtx.Lock()
defer fc.mtx.Unlock()
select {
case <-fc.start:
fc.active = true
return true
default:
return false
}
}