Scott Baker | ed4efab | 2020-01-13 19:12:25 -0800 | [diff] [blame] | 1 | // Copyright 2018 The Go Authors. All rights reserved. |
| 2 | // Use of this source code is governed by a BSD-style |
| 3 | // license that can be found in the LICENSE file. |
| 4 | |
| 5 | package socks |
| 6 | |
| 7 | import ( |
| 8 | "context" |
| 9 | "errors" |
| 10 | "io" |
| 11 | "net" |
| 12 | "strconv" |
| 13 | "time" |
| 14 | ) |
| 15 | |
| 16 | var ( |
| 17 | noDeadline = time.Time{} |
| 18 | aLongTimeAgo = time.Unix(1, 0) |
| 19 | ) |
| 20 | |
| 21 | func (d *Dialer) connect(ctx context.Context, c net.Conn, address string) (_ net.Addr, ctxErr error) { |
| 22 | host, port, err := splitHostPort(address) |
| 23 | if err != nil { |
| 24 | return nil, err |
| 25 | } |
| 26 | if deadline, ok := ctx.Deadline(); ok && !deadline.IsZero() { |
| 27 | c.SetDeadline(deadline) |
| 28 | defer c.SetDeadline(noDeadline) |
| 29 | } |
| 30 | if ctx != context.Background() { |
| 31 | errCh := make(chan error, 1) |
| 32 | done := make(chan struct{}) |
| 33 | defer func() { |
| 34 | close(done) |
| 35 | if ctxErr == nil { |
| 36 | ctxErr = <-errCh |
| 37 | } |
| 38 | }() |
| 39 | go func() { |
| 40 | select { |
| 41 | case <-ctx.Done(): |
| 42 | c.SetDeadline(aLongTimeAgo) |
| 43 | errCh <- ctx.Err() |
| 44 | case <-done: |
| 45 | errCh <- nil |
| 46 | } |
| 47 | }() |
| 48 | } |
| 49 | |
| 50 | b := make([]byte, 0, 6+len(host)) // the size here is just an estimate |
| 51 | b = append(b, Version5) |
| 52 | if len(d.AuthMethods) == 0 || d.Authenticate == nil { |
| 53 | b = append(b, 1, byte(AuthMethodNotRequired)) |
| 54 | } else { |
| 55 | ams := d.AuthMethods |
| 56 | if len(ams) > 255 { |
| 57 | return nil, errors.New("too many authentication methods") |
| 58 | } |
| 59 | b = append(b, byte(len(ams))) |
| 60 | for _, am := range ams { |
| 61 | b = append(b, byte(am)) |
| 62 | } |
| 63 | } |
| 64 | if _, ctxErr = c.Write(b); ctxErr != nil { |
| 65 | return |
| 66 | } |
| 67 | |
| 68 | if _, ctxErr = io.ReadFull(c, b[:2]); ctxErr != nil { |
| 69 | return |
| 70 | } |
| 71 | if b[0] != Version5 { |
| 72 | return nil, errors.New("unexpected protocol version " + strconv.Itoa(int(b[0]))) |
| 73 | } |
| 74 | am := AuthMethod(b[1]) |
| 75 | if am == AuthMethodNoAcceptableMethods { |
| 76 | return nil, errors.New("no acceptable authentication methods") |
| 77 | } |
| 78 | if d.Authenticate != nil { |
| 79 | if ctxErr = d.Authenticate(ctx, c, am); ctxErr != nil { |
| 80 | return |
| 81 | } |
| 82 | } |
| 83 | |
| 84 | b = b[:0] |
| 85 | b = append(b, Version5, byte(d.cmd), 0) |
| 86 | if ip := net.ParseIP(host); ip != nil { |
| 87 | if ip4 := ip.To4(); ip4 != nil { |
| 88 | b = append(b, AddrTypeIPv4) |
| 89 | b = append(b, ip4...) |
| 90 | } else if ip6 := ip.To16(); ip6 != nil { |
| 91 | b = append(b, AddrTypeIPv6) |
| 92 | b = append(b, ip6...) |
| 93 | } else { |
| 94 | return nil, errors.New("unknown address type") |
| 95 | } |
| 96 | } else { |
| 97 | if len(host) > 255 { |
| 98 | return nil, errors.New("FQDN too long") |
| 99 | } |
| 100 | b = append(b, AddrTypeFQDN) |
| 101 | b = append(b, byte(len(host))) |
| 102 | b = append(b, host...) |
| 103 | } |
| 104 | b = append(b, byte(port>>8), byte(port)) |
| 105 | if _, ctxErr = c.Write(b); ctxErr != nil { |
| 106 | return |
| 107 | } |
| 108 | |
| 109 | if _, ctxErr = io.ReadFull(c, b[:4]); ctxErr != nil { |
| 110 | return |
| 111 | } |
| 112 | if b[0] != Version5 { |
| 113 | return nil, errors.New("unexpected protocol version " + strconv.Itoa(int(b[0]))) |
| 114 | } |
| 115 | if cmdErr := Reply(b[1]); cmdErr != StatusSucceeded { |
| 116 | return nil, errors.New("unknown error " + cmdErr.String()) |
| 117 | } |
| 118 | if b[2] != 0 { |
| 119 | return nil, errors.New("non-zero reserved field") |
| 120 | } |
| 121 | l := 2 |
| 122 | var a Addr |
| 123 | switch b[3] { |
| 124 | case AddrTypeIPv4: |
| 125 | l += net.IPv4len |
| 126 | a.IP = make(net.IP, net.IPv4len) |
| 127 | case AddrTypeIPv6: |
| 128 | l += net.IPv6len |
| 129 | a.IP = make(net.IP, net.IPv6len) |
| 130 | case AddrTypeFQDN: |
| 131 | if _, err := io.ReadFull(c, b[:1]); err != nil { |
| 132 | return nil, err |
| 133 | } |
| 134 | l += int(b[0]) |
| 135 | default: |
| 136 | return nil, errors.New("unknown address type " + strconv.Itoa(int(b[3]))) |
| 137 | } |
| 138 | if cap(b) < l { |
| 139 | b = make([]byte, l) |
| 140 | } else { |
| 141 | b = b[:l] |
| 142 | } |
| 143 | if _, ctxErr = io.ReadFull(c, b); ctxErr != nil { |
| 144 | return |
| 145 | } |
| 146 | if a.IP != nil { |
| 147 | copy(a.IP, b) |
| 148 | } else { |
| 149 | a.Name = string(b[:len(b)-2]) |
| 150 | } |
| 151 | a.Port = int(b[len(b)-2])<<8 | int(b[len(b)-1]) |
| 152 | return &a, nil |
| 153 | } |
| 154 | |
| 155 | func splitHostPort(address string) (string, int, error) { |
| 156 | host, port, err := net.SplitHostPort(address) |
| 157 | if err != nil { |
| 158 | return "", 0, err |
| 159 | } |
| 160 | portnum, err := strconv.Atoi(port) |
| 161 | if err != nil { |
| 162 | return "", 0, err |
| 163 | } |
| 164 | if 1 > portnum || portnum > 0xffff { |
| 165 | return "", 0, errors.New("port number out of range " + port) |
| 166 | } |
| 167 | return host, portnum, nil |
| 168 | } |