123 lines
2.5 KiB
Go
123 lines
2.5 KiB
Go
package connection
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import (
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"context"
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"encoding/json"
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"net"
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"os/exec"
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"strconv"
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"strings"
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"sync"
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"time"
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omd "git.loafle.net/overflow/model/discovery"
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omm "git.loafle.net/overflow/model/meta"
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omu "git.loafle.net/overflow/model/util"
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"git.loafle.net/overflow_scanner/probe/discovery/session"
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"golang.org/x/sync/semaphore"
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)
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const (
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defaultUlimit = 1024
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)
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func Scan(discoverySession session.DiscoverySession, targetHost *omd.Host) error {
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if nil == targetHost || nil == discoverySession.DiscoverPort() || !discoverySession.DiscoverPort().IncludeTCP {
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return nil
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}
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dp := discoverySession.DiscoverPort()
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lock := semaphore.NewWeighted(Ulimit())
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var wg sync.WaitGroup
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stopChan := make(chan struct{})
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timeout := 500 * time.Millisecond
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ports := make(map[int]*omd.Port)
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Loop:
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for portNumber := dp.FirstScanRange; portNumber < dp.LastScanRange; portNumber++ {
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if nil != dp.ExcludePorts {
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for _, exPortNumber := range dp.ExcludePorts {
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if portNumber == exPortNumber {
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continue Loop
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}
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}
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}
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lock.Acquire(context.TODO(), 1)
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wg.Add(1)
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go func(port int) {
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defer func() {
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lock.Release(1)
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wg.Done()
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}()
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tryConnect(discoverySession, ports, targetHost, port, timeout, stopChan)
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}(portNumber)
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select {
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case <-time.After(time.Microsecond * 100):
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case <-discoverySession.StopChan():
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close(stopChan)
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return nil
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}
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}
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wg.Wait()
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return nil
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}
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func tryConnect(discoverySession session.DiscoverySession, ports map[int]*omd.Port, targetHost *omd.Host, port int, timeout time.Duration, stopChan <-chan struct{}) {
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addr := net.JoinHostPort(targetHost.Address, strconv.Itoa(port))
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conn, err := net.DialTimeout("tcp", addr, timeout)
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dp := discoverySession.DiscoverPort()
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if err != nil {
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if strings.Contains(err.Error(), "too many open files") {
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select {
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case <-stopChan:
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return
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default:
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}
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time.Sleep(timeout)
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tryConnect(discoverySession, ports, targetHost, port, timeout, stopChan)
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}
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return
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}
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conn.Close()
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if _, ok := ports[port]; ok || !dp.Contains(port) {
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return
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}
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p := &omd.Port{
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MetaPortType: omm.ToMetaPortType(omm.MetaPortTypeEnumTCP),
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PortNumber: json.Number(strconv.Itoa(port)),
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DiscoveredDate: omu.NowPtr(),
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}
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p.Host = targetHost
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ports[port] = p
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go discoverySession.AddPort("UDP Connection", p, nil)
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}
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func Ulimit() int64 {
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out, err := exec.Command("ulimit", "-n").Output()
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if nil != err {
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return defaultUlimit
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}
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s := strings.TrimSpace(string(out))
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i, err := strconv.ParseInt(s, 10, 64)
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if nil != err {
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return defaultUlimit
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}
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return i
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}
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