forked from quic-go/quic-go
58 lines
1.6 KiB
Go
58 lines
1.6 KiB
Go
package handshake
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import (
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"bytes"
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"crypto/subtle"
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"errors"
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"net"
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"time"
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"github.com/lucas-clemente/quic-go/crypto"
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)
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// An STKGenerator generates STKs
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type STKGenerator struct {
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stkSource crypto.StkSource
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}
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// NewSTKGenerator initializes a new STKGenerator
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func NewSTKGenerator() (*STKGenerator, error) {
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stkSource, err := crypto.NewStkSource()
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if err != nil {
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return nil, err
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}
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return &STKGenerator{
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stkSource: stkSource,
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}, nil
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}
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// NewToken generates a new STK token for a given source address
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func (g *STKGenerator) NewToken(raddr net.Addr) ([]byte, error) {
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return g.stkSource.NewToken(encodeRemoteAddr(raddr))
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}
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// VerifyToken verifies an STK token
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func (g *STKGenerator) VerifyToken(raddr net.Addr, data []byte) (time.Time, error) {
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data, timestamp, err := g.stkSource.DecodeToken(data)
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if err != nil {
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return time.Time{}, err
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}
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if subtle.ConstantTimeCompare(encodeRemoteAddr(raddr), data) != 1 {
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return time.Time{}, errors.New("invalid source address in STK")
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}
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return timestamp, nil
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}
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// encodeRemoteAddr encodes a remote address such that it can be saved in the STK
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// it ensures that we're binary compatible with Google's implementation of STKs
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func encodeRemoteAddr(remoteAddr net.Addr) []byte {
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// if the address is a UDP address, just use the byte representation of the IP address
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// the length of an IP address is 4 bytes (for IPv4) or 16 bytes (for IPv6)
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if udpAddr, ok := remoteAddr.(*net.UDPAddr); ok {
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return udpAddr.IP
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}
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// if the address is not a UDP address, prepend 16 bytes
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// that way it can be distinguished from an IP address
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return append(bytes.Repeat([]byte{0}, 16), []byte(remoteAddr.String())...)
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}
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