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ssm.go

+package main
+
+import (
+    //"encoding/binary"
+    "fmt"
+    "net"
+    "os"
+    "encoding/binary"
+    //"runtime"
+    "time"
+    "regexp"
+    "golang.org/x/net/ipv4"
+
+)
+
+func usage() {
+        fmt.Println("USAGE: ssm <source>%<group>:<port>\n")
+        os.Exit(0)
+}
+
+func main() {
+    arguments := os.Args
+    if len(arguments) < 2 {
+            usage()
+    }
+
+    /* Process the SSM group join argument */
+
+    ssmarg := arguments[1]
+    re := regexp.MustCompile("^(.*)%(.*):([0-9]+)$")
+
+    if re.MatchString(ssmarg) == false  {
+        usage()
+    }
+
+    ssm := re.FindAllStringSubmatch(ssmarg, -1)[0]
+    source := ssm[1]
+    group := ssm[2]
+    port := ssm[3]
+
+    var bindif string
+    allnets, _ := net.Interfaces()
+
+    if(len(allnets) == 0) {
+      fmt.Printf("Did not find any network interfaces\n")
+      return
+    } else if (len(allnets) == 1) {
+      // Only one interface available so use that.
+      bindif = allnets[0].Name
+    } else {
+      bindif = allnets[1].Name
+    }
+
+    if len(arguments) == 4 {
+      switch(arguments[2]) {
+        case "-i":
+            bindif = arguments[3]
+          default:
+                  fmt.Printf("INVALID ARG: %v\n", arguments[2])
+                  usage()
+        }
+
+    }
+
+    ssmif, err := net.InterfaceByName(bindif)
+    if err != nil {
+            fmt.Printf("Could not bind to interface '%v'\n", bindif)
+        return
+    }
+
+    c, err := net.ListenPacket("udp4", "0.0.0.0:" + port)
+
+    if err != nil {
+        fmt.Println(err)
+        return
+    }
+
+    fmt.Printf("Server listening on UDP port %v\nJoining multicast (S,G)=%v,%v w/iface %v\n", port, source, group, bindif)
+
+    defer c.Close()
+
+    p := ipv4.NewPacketConn(c)
+
+    ssmsource := net.UDPAddr{IP: net.ParseIP(source)}
+    ssmgroup := net.UDPAddr{IP: net.ParseIP(group)}
+
+    if err := p.JoinSourceSpecificGroup(ssmif, &ssmgroup, &ssmsource); err != nil {
+        // error handling
+           fmt.Println(err)
+        return
+    }
+
+    b := make([]byte, 1500)
+    var index int32
+    var last_index int32
+    index = 0
+    last_index = 0
+    first_packet := true
+    packet_count := 0
+    var stream_start time.Time
+
+
+    for {
+        n, _, _, err := p.ReadFrom(b)
+        if err != nil {
+                // error handling
+           fmt.Println(err)
+        return
+        }
+        if n != 0 {
+          packet_count++
+          index = int32(binary.BigEndian.Uint32(b[0:4]))
+          if index < 0 {
+                  // end of stream
+                  fmt.Printf("!EOS [i:%v]\n", index)
+                  first_packet = true
+                  packet_count = 0
+                  last_index = 0
+                  index = 0
+                  continue
+          }
+
+          if first_packet {
+                  fmt.Printf("S: %v", index)
+                  first_packet = false
+                  stream_start = time.Now()
+          } else if index == (last_index + 1){
+                  fmt.Printf("\033[32m!\033[0m")
+          } else if index < last_index {
+                  fmt.Printf("\033[34m<\033[0m")
+          } else if index > (last_index + 1) {
+                  fmt.Printf("\033[36m>\033[0m")
+          } else {
+                  fmt.Printf("\033[31m.\033[0m")
+          }
+          last_index = index
+
+          if time.Since(stream_start)/time.Second >= 5 {
+            fmt.Printf("[%vpps]", packet_count/5)
+            stream_start = time.Now()
+            packet_count = 0
+          }
+        } else {
+          break
+        }
+    }
+
+    if err := p.LeaveSourceSpecificGroup(ssmif, &ssmgroup, &ssmsource); err != nil {
+        // error handling
+           fmt.Println(err)
+        return
+    }
+}
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