Update ping binary to behave more like iputils ping

README.md

@@ -4,6 +4,8 @@
 
 Simple (ICMP) library patterned after net/http.
 
+Originally inspired by [sparrc/go-ping](https://github.com/sparrc/go-ping)
+
 
 ### Installation
 
@@ -50,7 +52,7 @@ System installed `ping` binaries generally have `setuid` attributes set, thus al
 setcap cap_net_raw=eip /path/to/your/application
 ```
 
-Since this library can utilize unprivileged raw sockets on Linux and Darwin (`udp4` or `udp6` as the network). On Linux, the system group of the user running the application must be allowed to create unprivileged ICMP sockets. [See man pages icmp(7) for `ping_group_range`](http://man7.org/linux/man-pages/man7/icmp.7.html).
+This library tries to initialize a privileged ICMP socket before falling back to unprivileged raw sockets on Linux and Darwin (`udp4` or `udp6` as the network). On Linux, the system group of the user running the application must be allowed to create unprivileged ICMP sockets if desired. [See man pages icmp(7) for `ping_group_range`](http://man7.org/linux/man-pages/man7/icmp.7.html).
 
 To allow a range of groups access to create unprivileged icmp sockets on linux (ipv4 or ipv6), run:
 

cmd/ping/README.md

@@ -0,0 +1,102 @@
+## ping
+
+Send ICMP ECHO_REQUEST to network hosts
+
+`ping` uses the ICMP protocol's mandatory ECHO_REQUEST datagram to elicit an ICMP ECHO_RESPONSE from a host or gateway. ECHO_REQUEST datagrams (pings) have an IP and ICMP header, followed by an arbitrary number of padbytes used to fill out the packet.
+
+`ping` works with both IPv4 and IPv6. Using only one of them explicitly can be enforced by specifying -4 or -6.
+
+
+#### Installation
+
+```sh
+go get github.com/glinton/ping/cmd/ping
+# to run:
+$GOPATH/bin/ping google.com
+```
+
+
+#### Usage
+```
+ping [-h] [-4] [-6] [-c count] [-i interval] [-I interface]
+     [-w deadline] [-W timeout] [-s packetsize] destination
+
+-4
+    Use IPv4 only.
+
+-6
+    Use IPv6 only.
+
+-c count
+    Stop after sending count ECHO_REQUEST packets. With deadline
+    option, ping waits for count ECHO_REPLY packets, until the timeout
+    expires.
+
+-h
+    Show help.
+
+-i interval
+    Wait interval seconds between sending each packet. The default is
+    to wait for one second between each packet normally. Interval values
+    less than 200 milliseconds (200ms) are not allowed.
+
+-I interface
+    interface is either an address, or an interface name. If interface
+    is an address, it sets source address to specified interface
+    address. If interface in an interface name, it sets source
+    interface to specified interface.
+
+-s packetsize
+    Specifies the number of data bytes to be sent. The default is 56,
+    which translates into 64 ICMP data bytes when combined with the 8
+    bytes of ICMP header data.
+
+-w deadline
+    Specify a timeout, in seconds, before ping exits regardless of how
+    many packets have been sent or received. In this case ping does not
+    stop after count packet are sent, it waits either for deadline
+    expire or until count probes are answered or for some error
+    notification from network.
+
+-W timeout
+    Time to wait for a response, in seconds. The option affects only
+    timeout in absence of any responses.
+```
+
+
+#### Examples
+
+```
+# ping google continuously
+ping google.com
+
+# ping google 5 times
+ping -c 5 google.com
+
+# ping google 5 times at 500ms intervals
+ping -c 5 -i .5 google.com
+
+# ping google for 10 seconds
+ping -w 10 google.com
+```
+
+
+#### Notes Regarding ICMP Socket Permissions
+
+System installed `ping` binaries generally have `setuid` attributes set, thus allowing them to utilize privileged ICMP sockets. This should work for applications built with this library as well, but a better approach would be to give the application the capability to create privileged ICMP sockets. To do so, run the following as the `root` user (not applicable to Windows).
+
+```
+setcap cap_net_raw=eip /gopath/bin/ping
+```
+
+If you desire to utilize unprivileged raw sockets on Linux, the system group of the user running ping must be allowed to create unprivileged ICMP sockets. [See man pages icmp(7) for `ping_group_range`](http://man7.org/linux/man-pages/man7/icmp.7.html).
+
+To allow a range of groups access to create unprivileged icmp sockets on linux (ipv4 or ipv6), run:
+
+```
+sudo sysctl -w net.ipv4.ping_group_range="GROUPID_START GROUPID_END"
+```
+
+If you plan to run your application as `root`, the aforementioned commmand is not necessary.
+
+On Windows, running a terminal as admin should not be necessary.

cmd/ping/ping.go → cmd/ping/main.go

@@ -7,8 +7,11 @@ import (
 	"fmt"
 	"math"
 	"net"
+	"os"
+	"os/signal"
 	"strings"
 	"sync"
+	"syscall"
 	"time"
 
 	"github.com/glinton/ping"
@@ -18,11 +21,11 @@ func main() {
 	ipv4 := flag.Bool("-4", false, "")
 	ipv6 := flag.Bool("-6", false, "")
 	count := flag.Int("c", 0, "")
-	interval := flag.Duration("i", time.Second, "")
+	interval := flag.Float64("i", 1, "")
 	iface := flag.String("I", "", "")
 	size := flag.Int("-s", 0, "")
-	deadline := flag.Duration("w", time.Millisecond*5000, "")
-	timeout := flag.Duration("W", time.Second, "")
+	deadline := flag.Float64("w", 0, "")
+	timeout := flag.Float64("W", 1, "")
 
 	flag.Usage = func() {
 		fmt.Print(usage)
@@ -52,12 +55,28 @@ func main() {
 		return
 	}
 
-	tick := time.NewTicker(*interval)
-	defer tick.Stop()
+	fmt.Printf("PING %s (%s) %d bytes of data.\n", destination, host.String(), len(data))
+
+	ctx := term(context.Background())
 
 	wg := &sync.WaitGroup{}
-	ctx, cancel := context.WithTimeout(context.Background(), *deadline)
-	defer cancel()
+	var cancel context.CancelFunc
+	if *deadline > 0 {
+		ctx, cancel = context.WithTimeout(ctx, time.Duration(*deadline*float64(time.Second)))
+		defer cancel()
+	}
+
+	if *timeout <= 0 {
+		*timeout = 2
+	}
+
+	if *interval < .2 {
+		fmt.Println("ping: cannot flood; minimal interval allowed for user is 200ms")
+		return
+	}
+
+	tick := time.NewTicker(time.Duration(*interval * float64(time.Second)))
+	defer tick.Stop()
 
 	chanLength := 100
 	if *count > 0 {
@@ -73,8 +92,6 @@ func main() {
 		name = strings.TrimSuffix(names[0], ".")
 	}
 
-	fmt.Printf("PING %s (%s) %d bytes of data.\n", destination, host.String(), len(data))
-
 	req := ping.Request{
 		Dst:  net.ParseIP(host.String()),
 		Src:  net.ParseIP(getAddr(*iface)),
@@ -85,7 +102,7 @@ func main() {
 		case <-ctx.Done():
 			goto finish
 		case <-tick.C:
-			ctx, cancel := context.WithTimeout(context.Background(), *timeout)
+			ctx, cancel := context.WithTimeout(context.Background(), time.Duration(*timeout*float64(time.Second)))
 			defer cancel()
 
 			packetsSent++
@@ -209,6 +226,25 @@ func getAddr(ipOrIface string) string {
 	return ""
 }
 
+// Handle signals in the fanciest way. Thanks to:
+// https://github.com/influxdata/influxdb/blob/v2.0.0-alpha.14/kit/signals/context.go
+func term(ctx context.Context) context.Context {
+	sigCh := make(chan os.Signal, 1)
+	signal.Notify(sigCh, os.Interrupt, syscall.SIGTERM)
+
+	ctx, cancel := context.WithCancel(ctx)
+	go func() {
+		defer cancel()
+		select {
+		case <-ctx.Done():
+			return
+		case <-sigCh:
+			return
+		}
+	}()
+	return ctx
+}
+
 var usage = `
 NAME
        ping - send ICMP ECHO_REQUEST to network hosts
@@ -220,8 +256,8 @@ SYNOPSIS
 DESCRIPTION
        ping uses the ICMP protocol's mandatory ECHO_REQUEST datagram to elicit
        an ICMP ECHO_RESPONSE from a host or gateway. ECHO_REQUEST datagrams
-       (pings) have an IP and ICMP header, followed by a struct timeval and
-       then an arbitrary number of padbytes used to fill out the packet.
+			 (pings) have an IP and ICMP header, followed by an arbitrary number
+			 of padbytes used to fill out the packet.
 
        ping works with both IPv4 and IPv6. Using only one of them explicitly
        can be enforced by specifying -4 or -6.
@@ -266,8 +302,7 @@ OPTIONS
 
        -W timeout
            Time to wait for a response, in seconds. The option affects only
-           timeout in absence of any responses, otherwise ping waits for two
-           seconds.
+           timeout in absence of any responses.
 
 EXAMPLES
        # ping google continuously
@@ -277,8 +312,8 @@ EXAMPLES
        ping -c 5 www.google.com
 
        # ping google 5 times at 500ms intervals
-       ping -c 5 -i 500ms www.google.com
+       ping -c 5 -i .5 www.google.com
 
        # ping google for 10 seconds
-       ping -w 10s www.google.com
+       ping -w 10 www.google.com
 `