mirrors/uquic
1
0
Fork 0
mirror of https://github.com/refraction-networking/uquic.git synced 2025-04-03 20:27:35 +03:00
Code Issues Projects Releases Packages Wiki Activity

use non-cryptographic random to generate skipped packet numbers

Browse source
This commit is contained in:
Marten Seemann 2020-11-26 13:11:53 +07:00
parent 325bc1694d
commit e8e6c7b47e
2 changed files with 38 additions and 64 deletions
Download patch file Download diff file Expand all files Collapse all files

21
internal/ackhandler/packet_number_generator.go
View file

@ -2,7 +2,8 @@ package ackhandler
import (
"crypto/rand"
"math"
"encoding/binary"
mrand "math/rand"
"github.com/lucas-clemente/quic-go/internal/protocol"
)
@ -11,6 +12,7 @@ import (
// it randomly skips a packet number every averagePeriod packets (on average).
// It is guaranteed to never skip two consecutive packet numbers.
type packetNumberGenerator struct {
rand *mrand.Rand
averagePeriod protocol.PacketNumber
next protocol.PacketNumber
@ -18,7 +20,10 @@ type packetNumberGenerator struct {
}
func newPacketNumberGenerator(initial, averagePeriod protocol.PacketNumber) *packetNumberGenerator {
b := make([]byte, 8)
rand.Read(b) // it's not the end of the world if we don't get perfect random here
g := &packetNumberGenerator{
rand: mrand.New(mrand.NewSource(int64(binary.LittleEndian.Uint64(b)))),
next: initial,
averagePeriod: averagePeriod,
}
@ -44,18 +49,6 @@ func (p *packetNumberGenerator) Pop() protocol.PacketNumber {
}
func (p *packetNumberGenerator) generateNewSkip() {
num := p.getRandomNumber()
skip := protocol.PacketNumber(num) * (p.averagePeriod - 1) / (math.MaxUint16 / 2)
// make sure that there are never two consecutive packet numbers that are skipped
p.nextToSkip = p.next + 2 + skip
}
// getRandomNumber() generates a cryptographically secure random number between 0 and MaxUint16 (= 65535)
// The expectation value is 65535/2
func (p *packetNumberGenerator) getRandomNumber() uint16 {
b := make([]byte, 2)
rand.Read(b) // ignore the error here
num := uint16(b[0])<<8 + uint16(b[1])
return num
p.nextToSkip = p.next + 2 + protocol.PacketNumber(p.rand.Int31n(int32(2*p.averagePeriod)))
}