|
| 1 | +package main |
| 2 | + |
| 3 | +import ( |
| 4 | + "fmt" |
| 5 | + "net" |
| 6 | + "os" |
| 7 | + |
| 8 | + "neomantra/srv-plz/pkg/lookup" |
| 9 | + |
| 10 | + "github.com/spf13/pflag" |
| 11 | +) |
| 12 | + |
| 13 | +///////////////////////////////////////////////////////////////////////////////////// |
| 14 | + |
| 15 | +var usageFormatShort string = `usage: %s <options> [service1 [service2 [...]]]` |
| 16 | + |
| 17 | +var usageFormat string = `usage: %s <options> [service1 [service2 [...]]] |
| 18 | +
|
| 19 | +srv-plz resolves DNS SRV records and outputs the result. |
| 20 | +
|
| 21 | +The resolver is specified with "--dns <ip:port>" argument or by setting |
| 22 | +the SRV_DNS environment variable. The CLI argument takes precedent. |
| 23 | +
|
| 24 | +If no DNS resolver is specified, the system resolver is used. |
| 25 | +
|
| 26 | +` |
| 27 | + |
| 28 | +///////////////////////////////////////////////////////////////////////////////////// |
| 29 | + |
| 30 | +func main() { |
| 31 | + var dnsServer string |
| 32 | + var recurse bool |
| 33 | + var numLimit uint32 |
| 34 | + var showHelp bool |
| 35 | + |
| 36 | + pflag.StringVarP(&dnsServer, "dns", "d", "", "DNS resolver to use (must be in form IP:port)") |
| 37 | + pflag.BoolVarP(&recurse, "recurse", "r", false, "recurse with the same resolver") |
| 38 | + pflag.Uint32VarP(&numLimit, "limit", "l", 1, "only return N records") |
| 39 | + pflag.BoolVarP(&showHelp, "help", "h", false, "show help") |
| 40 | + pflag.Parse() |
| 41 | + |
| 42 | + if showHelp { |
| 43 | + fmt.Fprintf(os.Stdout, usageFormat, os.Args[0]) |
| 44 | + pflag.PrintDefaults() |
| 45 | + os.Exit(0) |
| 46 | + } |
| 47 | + |
| 48 | + // setup resolver |
| 49 | + if len(dnsServer) == 0 { |
| 50 | + // try from environment if not already set by CLI |
| 51 | + dnsServer = os.Getenv("SRV_DNS") |
| 52 | + } |
| 53 | + if len(dnsServer) != 0 { |
| 54 | + // check addr:port form is valid |
| 55 | + _, _, err := net.SplitHostPort(dnsServer) |
| 56 | + if err != nil { |
| 57 | + fmt.Fprintf(os.Stderr, "error: %v\n", err) |
| 58 | + os.Exit(1) |
| 59 | + } |
| 60 | + } |
| 61 | + |
| 62 | + // lookup the services |
| 63 | + services := pflag.Args() |
| 64 | + if len(services) == 0 { |
| 65 | + fmt.Fprintf(os.Stderr, usageFormatShort, os.Args[0]) |
| 66 | + fmt.Fprintf(os.Stderr, "\ntry %s --help\n", os.Args[0]) |
| 67 | + os.Exit(0) |
| 68 | + } |
| 69 | + for _, service := range services { |
| 70 | + if len(dnsServer) != 0 { |
| 71 | + records, err := lookup.LookupSRVCustom(service, dnsServer, recurse) |
| 72 | + if err != nil { |
| 73 | + fmt.Fprintf(os.Stderr, "%v\n", err) |
| 74 | + continue |
| 75 | + } |
| 76 | + for _, record := range records { |
| 77 | + fmt.Printf("%s:%d\n", record.Target, record.Port) |
| 78 | + } |
| 79 | + } else { |
| 80 | + records, err := lookup.LookupSRVSystem(service, recurse) |
| 81 | + if err != nil { |
| 82 | + fmt.Fprintf(os.Stderr, "%v\n", err) |
| 83 | + continue |
| 84 | + } |
| 85 | + for _, record := range records { |
| 86 | + fmt.Printf("%s:%d\n", record.Target, record.Port) |
| 87 | + } |
| 88 | + } |
| 89 | + } |
| 90 | +} |
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