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packetcapture-client.go
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packetcapture-client.go
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/*
* Copyright (C) 2022 IBM, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
package main
import (
"flag"
"fmt"
"net"
"os"
"time"
)
var (
PORT = flag.String("connect_port", "9990", "TCP port to connect to for packet stream")
HOST = flag.String("connect_host", "localhost", "Packet Capture Agent IP")
FILENAME = flag.String("outfile", "", "Create and write to Filename.pcap")
)
func check(e error) {
if e != nil {
panic(e)
}
}
func main() {
fmt.Println("Starting Packet Capture Client.")
fmt.Println("By default, the read packets are printed on stdout.")
fmt.Println("To write to a pcap file use flag '-outfile=[filename]'")
fmt.Println("This creates a file [filename] and writes packets to it.")
fmt.Println("To view captured packets 'tcpdump -r [filename]'.")
flag.Parse()
tcpServer, err := net.ResolveTCPAddr("tcp", *HOST+":"+*PORT)
if err != nil {
println("ResolveTCPAddr failed:", err.Error())
os.Exit(1)
}
conn, err := net.DialTCP("tcp", nil, tcpServer)
if err != nil {
println("Dial failed:", err.Error())
os.Exit(1)
}
var f *os.File
if *FILENAME != "" {
f, err = os.Create(*FILENAME)
if err != nil {
os.Exit(1)
}
defer f.Close()
for {
received := make([]byte, 65535)
n, err := conn.Read(received)
if err != nil {
println("Read data failed:", err.Error())
os.Exit(1)
}
_, err = f.Write(received[:n])
check(err)
dt := time.Now()
fmt.Println(dt.Format("01-02-2006 15:04:05.000000"), ": Received Packet of length ", n)
}
} else {
fmt.Println("into else")
for {
received := make([]byte, 65535)
n, err := conn.Read(received)
if err != nil {
println("Read data failed:", err.Error())
os.Exit(1)
}
fmt.Println(received[:n])
}
}
conn.Close()
}