-
Notifications
You must be signed in to change notification settings - Fork 0
/
Copy pathmain.go
79 lines (73 loc) · 1.42 KB
/
main.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
package main
import (
"bufio"
"context"
"errors"
"flag"
"fmt"
"io"
"log"
"net"
"os"
"strings"
"sync"
"golang.org/x/sync/semaphore"
)
func main() {
flag.BoolVar(&hideError, "hideerror", false, "hide query ERROR")
flag.BoolVar(&hideNoEntry, "hidenoentry", false, "hide NOENTRY")
flag.Int64Var(&concurrency, "concurrency", 500, "concurrency of DNS query")
flag.Parse()
if concurrency < 0 {
log.Fatalf("concurrency should be positive: %d", concurrency)
}
err := masslookup(context.Background(), os.Stdout, os.Stdin)
if err != nil {
log.Fatal(err)
}
}
var (
hideError bool
hideNoEntry bool
concurrency int64
)
func masslookup(ctx context.Context, w io.Writer, r io.Reader) error {
br := bufio.NewReader(r)
var wg sync.WaitGroup
sem := semaphore.NewWeighted(concurrency)
for {
line, err := br.ReadString('\n')
if err != nil {
if errors.Is(err, io.EOF) {
break
}
return err
}
err = sem.Acquire(ctx, 1)
if err != nil {
return err
}
line = strings.TrimSpace(line)
wg.Add(1)
go func(q string) {
defer wg.Done()
defer sem.Release(1)
names, err := net.LookupAddr(q)
if err != nil {
if !hideError {
fmt.Fprintf(w, "%s\tERROR\t%s\n", q, err)
}
return
}
if len(names) == 0 {
if !hideNoEntry {
fmt.Fprintf(w, "%s\tNOENTRY\n", q)
}
return
}
fmt.Fprintf(w, "%s\tFOUND\t%s\n", q, strings.Join(names, " "))
}(line)
}
wg.Wait()
return nil
}