144 lines
3.6 KiB
Go
144 lines
3.6 KiB
Go
// Copyright (c) 2013-2014 The btcsuite developers
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// Use of this source code is governed by an ISC
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// license that can be found in the LICENSE file.
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package main
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import (
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"encoding/binary"
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"errors"
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"net"
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)
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const (
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torSucceeded = 0x00
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torGeneralError = 0x01
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torNotAllowed = 0x02
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torNetUnreachable = 0x03
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torHostUnreachable = 0x04
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torConnectionRefused = 0x05
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torTTLExpired = 0x06
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torCmdNotSupported = 0x07
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torAddrNotSupported = 0x08
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)
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var (
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// ErrTorInvalidAddressResponse indicates an invalid address was
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// returned by the Tor DNS resolver.
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ErrTorInvalidAddressResponse = errors.New("invalid address response")
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// ErrTorInvalidProxyResponse indicates the Tor proxy returned a
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// response in an unexpected format.
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ErrTorInvalidProxyResponse = errors.New("invalid proxy response")
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// ErrTorUnrecognizedAuthMethod indicates the authentication method
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// provided is not recognized.
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ErrTorUnrecognizedAuthMethod = errors.New("invalid proxy authentication method")
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torStatusErrors = map[byte]error{
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torSucceeded: errors.New("tor succeeded"),
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torGeneralError: errors.New("tor general error"),
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torNotAllowed: errors.New("tor not allowed"),
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torNetUnreachable: errors.New("tor network is unreachable"),
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torHostUnreachable: errors.New("tor host is unreachable"),
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torConnectionRefused: errors.New("tor connection refused"),
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torTTLExpired: errors.New("tor TTL expired"),
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torCmdNotSupported: errors.New("tor command not supported"),
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torAddrNotSupported: errors.New("tor address type not supported"),
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}
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)
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// torLookupIP uses Tor to resolve DNS via the SOCKS extension they provide for
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// resolution over the Tor network. Tor itself doesn't support ipv6 so this
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// doesn't either.
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func torLookupIP(host, proxy string) ([]net.IP, error) {
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conn, err := net.Dial("tcp", proxy)
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if err != nil {
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return nil, err
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}
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defer conn.Close()
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buf := []byte{'\x05', '\x01', '\x00'}
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_, err = conn.Write(buf)
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if err != nil {
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return nil, err
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}
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buf = make([]byte, 2)
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_, err = conn.Read(buf)
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if err != nil {
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return nil, err
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}
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if buf[0] != '\x05' {
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return nil, ErrTorInvalidProxyResponse
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}
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if buf[1] != '\x00' {
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return nil, ErrTorUnrecognizedAuthMethod
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}
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buf = make([]byte, 7+len(host))
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buf[0] = 5 // protocol version
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buf[1] = '\xF0' // Tor Resolve
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buf[2] = 0 // reserved
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buf[3] = 3 // Tor Resolve
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buf[4] = byte(len(host))
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copy(buf[5:], host)
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buf[5+len(host)] = 0 // Port 0
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_, err = conn.Write(buf)
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if err != nil {
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return nil, err
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}
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buf = make([]byte, 4)
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_, err = conn.Read(buf)
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if err != nil {
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return nil, err
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}
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if buf[0] != 5 {
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return nil, ErrTorInvalidProxyResponse
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}
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if buf[1] != 0 {
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if int(buf[1]) > len(torStatusErrors) {
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err = ErrTorInvalidProxyResponse
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} else {
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err := torStatusErrors[buf[1]]
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if err == nil {
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err = ErrTorInvalidProxyResponse
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}
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}
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return nil, err
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}
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if buf[3] != 1 {
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err := torStatusErrors[torGeneralError]
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return nil, err
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}
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buf = make([]byte, 4)
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bytes, err := conn.Read(buf)
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if err != nil {
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return nil, err
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}
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if bytes != 4 {
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return nil, ErrTorInvalidAddressResponse
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}
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r := binary.BigEndian.Uint32(buf)
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addr := make([]net.IP, 1)
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addr[0] = net.IPv4(byte(r>>24), byte(r>>16), byte(r>>8), byte(r))
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return addr, nil
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}
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// dnsDiscover looks up the list of peers resolved by DNS for all hosts in
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// seeders. If proxy is not "" then it is used as a tor proxy for the
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// resolution.
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func dnsDiscover(seeder string) ([]net.IP, error) {
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peers, err := btcdLookup(seeder)
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if err != nil {
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return nil, err
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}
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return peers, nil
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}
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