add UDP socket counts and rename to 'netstat'.

Closes #244

plugins/system/netstat.go

@@ -0,0 +1,66 @@
+package system
+
+import (
+	"fmt"
+	"syscall"
+
+	"github.com/influxdb/telegraf/plugins"
+)
+
+type NetStats struct {
+	ps PS
+}
+
+func (_ *NetStats) Description() string {
+	return "Read metrics about TCP status such as established, time wait etc and UDP sockets counts."
+}
+
+var tcpstatSampleConfig = ""
+
+func (_ *NetStats) SampleConfig() string {
+	return tcpstatSampleConfig
+}
+
+func (s *NetStats) Gather(acc plugins.Accumulator) error {
+	netconns, err := s.ps.NetConnections()
+	if err != nil {
+		return fmt.Errorf("error getting net connections info: %s", err)
+	}
+	counts := make(map[string]int)
+	counts["UDP"] = 0
+
+	// TODO: add family to tags or else
+	tags := map[string]string{}
+	for _, netcon := range netconns {
+		if netcon.Type == syscall.SOCK_DGRAM {
+			counts["UDP"] += 1
+			continue // UDP has no status
+		}
+		c, ok := counts[netcon.Status]
+		if !ok {
+			counts[netcon.Status] = 0
+		}
+		counts[netcon.Status] = c + 1
+	}
+	acc.Add("tcp_established", counts["ESTABLISHED"], tags)
+	acc.Add("tcp_syn_sent", counts["SYN_SENT"], tags)
+	acc.Add("tcp_syn_recv", counts["SYN_RECV"], tags)
+	acc.Add("tcp_fin_wait1", counts["FIN_WAIT1"], tags)
+	acc.Add("tcp_fin_wait2", counts["FIN_WAIT2"], tags)
+	acc.Add("tcp_time_wait", counts["TIME_WAIT"], tags)
+	acc.Add("tcp_close", counts["CLOSE"], tags)
+	acc.Add("tcp_close_wait", counts["CLOSE_WAIT"], tags)
+	acc.Add("tcp_last_ack", counts["LAST_ACK"], tags)
+	acc.Add("tcp_listen", counts["LISTEN"], tags)
+	acc.Add("tcp_closing", counts["CLOSING"], tags)
+	acc.Add("tcp_none", counts["NONE"], tags)
+	acc.Add("udp_socket", counts["UDP"], tags)
+
+	return nil
+}
+
+func init() {
+	plugins.Add("netstat", func() plugins.Plugin {
+		return &NetStats{ps: &systemPS{}}
+	})
+}