Implement Connection support for OpenBSD

This retrieves open TCP/UDP connections by using netstat(1)
File descriptors and pids are not supported.

net/net_openbsd.go

@@ -4,13 +4,18 @@ package net
 
 import (
 	"errors"
+	"fmt"
 	"os/exec"
+	"regexp"
 	"strconv"
 	"strings"
+	"syscall"
 
 	"github.com/shirou/gopsutil/internal/common"
 )
 
+var portMatch = regexp.MustCompile(`(.*)\.(\d+)$`)
+
 func ParseNetstat(output string, mode string,
 	iocs map[string]IOCountersStat) error {
 	lines := strings.Split(output, "\n")
@@ -146,8 +151,138 @@ func ProtoCounters(protocols []string) ([]ProtoCountersStat, error) {
 	return nil, errors.New("NetProtoCounters not implemented for openbsd")
 }
 
+func parseNetstatLine(line string) (ConnectionStat, error) {
+	f := strings.Fields(line)
+	if len(f) < 5 {
+		return ConnectionStat{}, fmt.Errorf("wrong line,%s", line)
+	}
+
+	var netType, netFamily uint32
+	switch f[0] {
+	case "tcp":
+		netType = syscall.SOCK_STREAM
+		netFamily = syscall.AF_INET
+	case "udp":
+		netType = syscall.SOCK_DGRAM
+		netFamily = syscall.AF_INET
+	case "tcp6":
+		netType = syscall.SOCK_STREAM
+		netFamily = syscall.AF_INET6
+	case "udp6":
+		netType = syscall.SOCK_DGRAM
+		netFamily = syscall.AF_INET6
+	default:
+		return ConnectionStat{}, fmt.Errorf("unknown type, %s", f[0])
+	}
+
+	laddr, raddr, err := parseNetstatAddr(f[3], f[4], netFamily)
+	if err != nil {
+		return ConnectionStat{}, fmt.Errorf("failed to parse netaddr, %s %s", f[3], f[4])
+	}
+
+	n := ConnectionStat{
+		Fd:     uint32(0), // not supported
+		Family: uint32(netFamily),
+		Type:   uint32(netType),
+		Laddr:  laddr,
+		Raddr:  raddr,
+		Pid:    int32(0), // not supported
+	}
+	if len(f) == 6 {
+		n.Status = f[5]
+	}
+
+	return n, nil
+}
+
+func parseNetstatAddr(local string, remote string, family uint32) (laddr Addr, raddr Addr, err error) {
+	parse := func(l string) (Addr, error) {
+		matches := portMatch.FindStringSubmatch(l)
+		if matches == nil {
+			return Addr{}, fmt.Errorf("wrong addr, %s", l)
+		}
+		host := matches[1]
+		port := matches[2]
+		if host == "*" {
+			if family == syscall.AF_INET {
+				host = "0.0.0.0"
+			} else {
+				host = "::"
+			}
+		}
+		lport, err := strconv.Atoi(port)
+		if err != nil {
+			return Addr{}, err
+		}
+		return Addr{IP: host, Port: uint32(lport)}, nil
+	}
+
+	laddr, err = parse(local)
+	if remote != "*.*" { // remote addr exists
+		raddr, err = parse(remote)
+		if err != nil {
+			return laddr, raddr, err
+		}
+	}
+
+	return laddr, raddr, err
+}
+
 // Return a list of network connections opened.
-// Not Implemented for OpenBSD
 func Connections(kind string) ([]ConnectionStat, error) {
-	return nil, errors.New("Connections not implemented for openbsd")
+	var ret []ConnectionStat
+
+	args := []string{"-na"}
+	switch strings.ToLower(kind) {
+	default:
+		fallthrough
+	case "":
+		fallthrough
+	case "all":
+		fallthrough
+	case "inet":
+
+	case "inet4":
+		args = append(args, "-finet")
+	case "inet6":
+		args = append(args, "-finet6")
+	case "tcp":
+		args = append(args, "-ptcp")
+	case "tcp4":
+		args = append(args, "-ptcp", "-finet")
+	case "tcp6":
+		args = append(args, "-ptcp", "-finet6")
+	case "udp":
+		args = append(args, "-pudp")
+	case "udp4":
+		args = append(args, "-pudp", "-finet")
+	case "udp6":
+		args = append(args, "-pudp", "-finet6")
+	case "unix":
+		return ret, common.ErrNotImplementedError
+	}
+
+	netstat, err := exec.LookPath("/usr/bin/netstat")
+	if err != nil {
+		return nil, err
+	}
+	out, err := invoke.Command(netstat, args...)
+
+	if err != nil {
+		return nil, err
+	}
+	lines := strings.Split(string(out), "\n")
+	for _, line := range lines {
+		if !(strings.HasPrefix(line, "tcp") || strings.HasPrefix(line, "udp")) {
+			continue
+		}
+		n, err := parseNetstatLine(line)
+		if err != nil {
+			continue
+		}
+
+		ret = append(ret, n)
+	}
+
+	return ret, nil
 }