Implement ListenPorts using sockstat exec

Signed-off-by: Anders F Björklund <anders.f.bjorklund@gmail.com>

pkg/guestagent/guestagent_freebsd.go

@@ -6,6 +6,7 @@ import (
 	"time"
 
 	"github.com/lima-vm/lima/pkg/guestagent/api"
+	"github.com/lima-vm/lima/pkg/guestagent/sockstat"
 	"github.com/sirupsen/logrus"
 )
 
@@ -103,6 +104,26 @@ func (a *agent) Events(ctx context.Context, ch chan api.Event) {
 
 func (a *agent) LocalPorts(ctx context.Context) ([]api.IPPort, error) {
 	var res []api.IPPort
+	tcpParsed, err := sockstat.ParseOutput()
+	if err != nil {
+		return res, err
+	}
+
+	for _, f := range tcpParsed {
+		switch f.Kind {
+		case sockstat.TCP4, sockstat.TCP6:
+		default:
+			continue
+		}
+		if f.State == sockstat.Listen {
+			res = append(res,
+				api.IPPort{
+					IP:   f.IP,
+					Port: int(f.Port),
+				})
+		}
+	}
+
 	return res, nil
 }
 

pkg/guestagent/sockstat/sockstat.go

@@ -0,0 +1,121 @@
+package sockstat
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"net"
+	"strconv"
+	"strings"
+)
+
+type Kind = string
+
+const (
+	TCP4 Kind = "tcp4"
+	TCP6 Kind = "tcp6"
+	// TODO: "udp4", "udp6"
+)
+
+type State = string
+
+const (
+	Listen State = "listen"
+)
+
+type Entry struct {
+	Kind  Kind   `json:"kind"`
+	IP    net.IP `json:"ip"`
+	Port  uint16 `json:"port"`
+	State State  `json:"state"`
+}
+
+func Parse(r io.Reader, state State) ([]Entry, error) {
+	var entries []Entry
+	sc := bufio.NewScanner(r)
+
+	fieldNames := make(map[string]int)
+	for i := 0; sc.Scan(); i++ {
+		line := strings.TrimSpace(sc.Text())
+		if line == "" {
+			continue
+		}
+		fields := strings.Fields(line)
+		switch i {
+		case 0:
+			for j := 0; j < len(fields); j++ {
+				fieldNames[fields[j]] = j
+			}
+			if _, ok := fieldNames["PROTO"]; !ok {
+				return nil, fmt.Errorf("field \"PROTO\" not found")
+			}
+
+		default:
+			proto := fields[fieldNames["PROTO"]]
+			var kind Kind
+			switch proto {
+			case "tcp4":
+				kind = TCP4
+			case "tcp6":
+				kind = TCP6
+			default:
+				return entries, fmt.Errorf("unknown protocol: %s", proto)
+			}
+			localAddress := fields[fieldNames["PROTO"]+1]
+			ip, port, err := ParseAddress(localAddress, kind)
+			if err != nil {
+				return entries, err
+			}
+			ent := Entry{
+				Kind:  kind,
+				IP:    ip,
+				Port:  port,
+				State: state,
+			}
+			entries = append(entries, ent)
+		}
+	}
+
+	if err := sc.Err(); err != nil {
+		return entries, err
+	}
+	return entries, nil
+}
+
+/*
+Linux:
+USER     PROCESS              PID      PROTO  SOURCE ADDRESS            FOREIGN ADDRESS           STATE
+root     systemd              1        tcp6   :::22                     :::*                      LISTEN
+root     sshd                 1580     tcp6   :::22                     :::*                      LISTEN
+
+FreeBSD:
+USER     COMMAND    PID   FD  PROTO  LOCAL ADDRESS         FOREIGN ADDRESS
+root     sshd         831 3   tcp6   *:22                  *:*
+root     sshd         831 4   tcp4   *:22                  *:*
+*/
+
+func ParseAddress(s string, kind Kind) (net.IP, uint16, error) {
+	split := strings.SplitN(s, ":", 2)
+	if len(split) != 2 {
+		return nil, 0, fmt.Errorf("unparsable address %q", s)
+	}
+
+	host := split[0]
+	if host == "*" {
+		switch kind {
+		case TCP4:
+			host = "0.0.0.0"
+		case TCP6:
+			host = "::"
+		}
+	}
+	ip := net.ParseIP(host)
+
+	port64, err := strconv.ParseUint(split[1], 10, 16)
+	if err != nil {
+		return nil, 0, fmt.Errorf("unparsable address %q: unparsable port %q", s, split[1])
+	}
+	port := uint16(port64)
+
+	return ip, port, nil
+}

pkg/guestagent/sockstat/sockstat_freebsd.go

@@ -0,0 +1,18 @@
+package sockstat
+
+import (
+	"os/exec"
+)
+
+// ParseOutput parses sockstat(1)
+func ParseOutput() ([]Entry, error) {
+	var res []Entry
+
+	cmd := exec.Command("sockstat", "-l", "-L", "-P", "tcp")
+	_,err := cmd.Output()
+	if err != nil {
+		return nil, err
+	}
+
+	return res,nil
+}