|
| 1 | +package hostagent |
| 2 | + |
| 3 | +import ( |
| 4 | + "context" |
| 5 | + "fmt" |
| 6 | + "net" |
| 7 | + "os" |
| 8 | + "path/filepath" |
| 9 | + "strconv" |
| 10 | + |
| 11 | + "github.com/lima-vm/sshocker/pkg/ssh" |
| 12 | + "github.com/norouter/norouter/pkg/agent/bicopy" |
| 13 | + "github.com/sirupsen/logrus" |
| 14 | +) |
| 15 | + |
| 16 | +// forwardTCP is not thread-safe |
| 17 | +func forwardTCP(ctx context.Context, l *logrus.Logger, sshConfig *ssh.SSHConfig, port int, local, remote string, cancel bool) error { |
| 18 | + localIPStr, localPortStr, err := net.SplitHostPort(local) |
| 19 | + if err != nil { |
| 20 | + return err |
| 21 | + } |
| 22 | + localIP := net.ParseIP(localIPStr) |
| 23 | + localPort, err := strconv.Atoi(localPortStr) |
| 24 | + if err != nil { |
| 25 | + return err |
| 26 | + } |
| 27 | + |
| 28 | + if !net.ParseIP("127.0.0.1").Equal(localIP) || localPort >= 1024 { |
| 29 | + return forwardSSH(ctx, sshConfig, port, local, remote, cancel) |
| 30 | + } |
| 31 | + |
| 32 | + // on macOS, listening on 127.0.0.1:80 requires root while 0.0.0.0:80 does not require root. |
| 33 | + // https://twitter.com/_AkihiroSuda_/status/1403403845842075648 |
| 34 | + // |
| 35 | + // We use "pseudoloopback" forwarder that listens on 0.0.0.0:80 but rejects connections from non-loopback src IP. |
| 36 | + l.Debugf("using pseudoloopback port forwarder for %q", local) |
| 37 | + |
| 38 | + if cancel { |
| 39 | + plf, ok := pseudoLoopbackForwarders[local] |
| 40 | + if ok { |
| 41 | + localUnix := plf.unixAddr.Name |
| 42 | + _ = plf.Close() |
| 43 | + delete(pseudoLoopbackForwarders, local) |
| 44 | + if err := forwardSSH(ctx, sshConfig, port, localUnix, remote, cancel); err != nil { |
| 45 | + return err |
| 46 | + } |
| 47 | + } else { |
| 48 | + l.Warnf("forwarding for %q seems already cancelled?", local) |
| 49 | + } |
| 50 | + return nil |
| 51 | + } |
| 52 | + |
| 53 | + localUnixDir, err := os.MkdirTemp("/tmp", fmt.Sprintf("lima-psl-%s-%d-", localIP, localPort)) |
| 54 | + if err != nil { |
| 55 | + return err |
| 56 | + } |
| 57 | + localUnix := filepath.Join(localUnixDir, "sock") |
| 58 | + l.Debugf("forwarding %q to %q", localUnix, remote) |
| 59 | + if err := forwardSSH(ctx, sshConfig, port, localUnix, remote, cancel); err != nil { |
| 60 | + if removeErr := os.RemoveAll(localUnixDir); removeErr != nil { |
| 61 | + l.WithError(removeErr).Warnf("failed to remove %q", removeErr) |
| 62 | + } |
| 63 | + return err |
| 64 | + } |
| 65 | + plf, err := newPseudoLoopbackForwarder(l, localPort, localUnix) |
| 66 | + if err != nil { |
| 67 | + if removeErr := os.RemoveAll(localUnixDir); removeErr != nil { |
| 68 | + l.WithError(removeErr).Warnf("failed to remove %q", removeErr) |
| 69 | + } |
| 70 | + if cancelErr := forwardSSH(ctx, sshConfig, port, localUnix, remote, true); cancelErr != nil { |
| 71 | + l.WithError(cancelErr).Warnf("failed to cancel forwarding %q to %q", localUnix, remote) |
| 72 | + } |
| 73 | + return err |
| 74 | + } |
| 75 | + plf.onClose = func() error { |
| 76 | + return os.RemoveAll(localUnixDir) |
| 77 | + } |
| 78 | + pseudoLoopbackForwarders[local] = plf |
| 79 | + go func() { |
| 80 | + if plfErr := plf.Serve(); plfErr != nil { |
| 81 | + l.WithError(plfErr).Warning("pseudoloopback forwarder crashed") |
| 82 | + } |
| 83 | + }() |
| 84 | + return nil |
| 85 | +} |
| 86 | + |
| 87 | +var pseudoLoopbackForwarders = make(map[string]*pseudoLoopbackForwarder) |
| 88 | + |
| 89 | +type pseudoLoopbackForwarder struct { |
| 90 | + l *logrus.Logger |
| 91 | + ln *net.TCPListener |
| 92 | + unixAddr *net.UnixAddr |
| 93 | + onClose func() error |
| 94 | +} |
| 95 | + |
| 96 | +func newPseudoLoopbackForwarder(l *logrus.Logger, localPort int, unixSock string) (*pseudoLoopbackForwarder, error) { |
| 97 | + unixAddr, err := net.ResolveUnixAddr("unix", unixSock) |
| 98 | + if err != nil { |
| 99 | + return nil, err |
| 100 | + } |
| 101 | + |
| 102 | + lnAddr, err := net.ResolveTCPAddr("tcp4", fmt.Sprintf("0.0.0.0:%d", localPort)) |
| 103 | + if err != nil { |
| 104 | + return nil, err |
| 105 | + } |
| 106 | + ln, err := net.ListenTCP("tcp4", lnAddr) |
| 107 | + if err != nil { |
| 108 | + return nil, err |
| 109 | + } |
| 110 | + |
| 111 | + plf := &pseudoLoopbackForwarder{ |
| 112 | + l: l, |
| 113 | + ln: ln, |
| 114 | + unixAddr: unixAddr, |
| 115 | + } |
| 116 | + |
| 117 | + return plf, nil |
| 118 | +} |
| 119 | + |
| 120 | +func (plf *pseudoLoopbackForwarder) Serve() error { |
| 121 | + defer plf.ln.Close() |
| 122 | + for { |
| 123 | + ac, err := plf.ln.AcceptTCP() |
| 124 | + if err != nil { |
| 125 | + return err |
| 126 | + } |
| 127 | + remoteAddr := ac.RemoteAddr().String() // ip:port |
| 128 | + remoteAddrIP, _, err := net.SplitHostPort(remoteAddr) |
| 129 | + if err != nil { |
| 130 | + plf.l.WithError(err).Debugf("pseudoloopback forwarder: rejecting non-loopback remoteAddr %q (unparsable)", remoteAddr) |
| 131 | + ac.Close() |
| 132 | + continue |
| 133 | + } |
| 134 | + if remoteAddrIP != "127.0.0.1" { |
| 135 | + plf.l.WithError(err).Debugf("pseudoloopback forwarder: rejecting non-loopback remoteAddr %q", remoteAddr) |
| 136 | + ac.Close() |
| 137 | + continue |
| 138 | + } |
| 139 | + go func(ac *net.TCPConn) { |
| 140 | + if fErr := plf.forward(ac); fErr != nil { |
| 141 | + plf.l.Error(fErr) |
| 142 | + } |
| 143 | + }(ac) |
| 144 | + } |
| 145 | +} |
| 146 | + |
| 147 | +func (plf *pseudoLoopbackForwarder) forward(ac *net.TCPConn) error { |
| 148 | + defer ac.Close() |
| 149 | + unixConn, err := net.DialUnix("unix", nil, plf.unixAddr) |
| 150 | + if err != nil { |
| 151 | + return err |
| 152 | + } |
| 153 | + defer unixConn.Close() |
| 154 | + bicopy.Bicopy(ac, unixConn, nil) |
| 155 | + return nil |
| 156 | +} |
| 157 | + |
| 158 | +func (plf *pseudoLoopbackForwarder) Close() error { |
| 159 | + _ = plf.ln.Close() |
| 160 | + return plf.onClose() |
| 161 | +} |
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