net-ping - homepage

This module implements ICMP Echo (ping) support for Node.js.

This module is installed using node package manager (npm):

npm install net-ping

It is loaded using the require() function:

var ping = require ("net-ping");

A ping session can then be created to ping or trace route to many hosts:

var session = ping.createSession ();

session.pingHost (target, function (error, target) {
    if (error)
        console.log (target + ": " + error.toString ());
    else
        console.log (target + ": Alive");
});

Network Protocol Support

This module supports IPv4 using the ICMP, and IPv6 using the ICMPv6.

Error Handling

Each request exposed by this module requires one or more mandatory callback functions. Callback functions are typically provided an error argument.

All errors are sub-classes of the Error class. For timed out errors the error passed to the callback function will be an instance of the ping.RequestTimedOutError class, with the exposed message attribute set to Request timed out.

This makes it easy to determine if a host responded, a time out occurred, or whether an error response was received:

session.pingHost ("1.2.3.4", function (error, target) {
    if (error)
        if (error instanceof ping.RequestTimedOutError)
            console.log (target + ": Not alive");
        else
            console.log (target + ": " + error.toString ());
    else
        console.log (target + ": Alive");
});

In addition to the the ping.RequestTimedOutError class, the following errors are also exported by this module to wrap ICMP error responses:

• DestinationUnreachableError
• PacketTooBigError
• ParameterProblemError
• RedirectReceivedError
• SourceQuenchError
• TimeExceededError

These errors are typically reported by hosts other than the intended target. In all cases each class exposes a source attribute which will specify the host who reported the error (which could be the intended target). This will also be included in the errors message attribute, i.e.:

$ sudo node example/ping-ttl.js 1 192.168.2.10 192.168.2.20 192.168.2.30
192.168.2.10: Alive
192.168.2.20: TimeExceededError: Time exceeded (source=192.168.1.1)
192.168.2.30: Not alive

The Session class will emit an error event for any other error not directly associated with a request. This is typically an instance of the Error class with the errors message attribute specifying the reason.

Packet Size

By default ICMP echo request packets sent by this module are 16 bytes in size. Some implementations cannot cope with such small ICMP echo requests. For example, some implementations will return an ICMP echo reply, but will include an incorrect ICMP checksum.

This module exposes a packetSize option to the createSession() method which specifies how big ICMP echo request packets should be:

var session = ping.createSession ({packetSize: 64});

Round Trip Times

Some callbacks used by methods exposed by this module provide two instances of the JavaScript Date class specifying when the first ping was sent for a request, and when a request completed.

These parameters are typically named sent and rcvd, and are provided to help round trip time calculation.

A request can complete in one of two ways. In the first, a ping response is received and rcvd - sent will yield the round trip time for the request in milliseconds.

In the second, no ping response is received resulting in a request time out. In this case rcvd - sent will yield the total time spent waiting for each retry to timeout if any. For example, if the retries option to the createSession() method was specified as 2 and timeout as 2000 then rcvd - sent will yield more than 6000 milliseconds.

Although this module provides instances of the Date class to help round trip time calculation the dates and times represented in each instance should not be considered 100% accurate.

Environmental conditions can affect when a date and time is actually calculated, e.g. garbage collection introducing a delay or the receipt of many packets at once. There are also a number of functions through which received packets must pass, which can also introduce a slight variable delay.

Throughout development experience has shown that, in general the smaller the round trip time the less accurate it will be - but the information is still useful nonetheless.

Constants

The following sections describe constants exported and used by this module.

ping.NetworkProtocol

This object contains constants which can be used for the networkProtocol option to the createSession() function exposed by this module. This option specifies the IP protocol version to use when creating the raw socket.

The following constants are defined in this object:

• IPv4 - IPv4 protocol
• IPv6 - IPv6 protocol

Using This Module

The Session class is used to issue ping and trace route requests to many hosts. This module exports the createSession() function which is used to create instances of the Session class.

ping.createSession ([options])

The createSession() function instantiates and returns an instance of the Session class:

// Default options
var options = {
    networkProtocol: ping.NetworkProtocol.IPv4,
    packetSize: 16,
    retries: 1,
    sessionId: (process.pid % 65535),
    timeout: 2000,
    ttl: 128
};

var session = ping.createSession (options);

The optional options parameter is an object, and can contain the following items:

• networkProtocol - Either the constant ping.NetworkProtocol.IPv4 or the constant ping.NetworkProtocol.IPv6, defaults to the constant ping.NetworkProtocol.IPv4
• packetSize - How many bytes each ICMP echo request packet should be, defaults to 16, if the value specified is less that 12 then the value 12 will be used (8 bytes are required for the ICMP packet itself, then 4 bytes are required to encode a unique session ID in the request and response packets)
• retries - Number of times to re-send a ping requests, defaults to 1
• sessionId - A unique ID used to identify request and response packets sent by this instance of the Session class, valid numbers are in the range of 1 to 65535, defaults to the value of process.pid % 65535
• timeout - Number of milliseconds to wait for a response before re-trying or failing, defaults to 2000
• ttl - Value to use for the IP header time to live field, defaults to 128

After creating the ping Session object an underlying raw socket will be created. If the underlying raw socket cannot be opened an exception with be thrown. The error will be an instance of the Error class.

Seperate instances of the Session class must be created for IPv4 and IPv6.

session.on ("close", callback)

The close event is emitted by the session when the underlying raw socket is closed.

No arguments are passed to the callback.

The following example prints a message to the console when the underlying raw socket is closed:

session.on ("close", function () {
    console.log ("socket closed");
});

session.on ("error", callback)

The error event is emitted by the session when the underlying raw socket emits an error.

The following arguments will be passed to the callback function:

• error - An instance of the Error class, the exposed message attribute will contain a detailed error message.

The following example prints a message to the console when an error occurs with the underlying raw socket, the session is then closed:

session.on ("error", function (error) {
    console.log (error.toString ());
    session.close ();
});

session.close ()

The close() method closes the underlying raw socket, and cancels all outstanding requsts.

The calback function for each outstanding ping requests will be called. The error parameter will be an instance of the Error class, and the message attribute set to Socket forcibly closed.

The sessoin can be re-used simply by submitting more ping requests, a new raw socket will be created to serve the new ping requests. This is a way in which to clear outstanding requests.

The following example submits a ping request and prints the target which successfully responded first, and then closes the session which will clear the other outstanding ping requests.

var targets = ["1.1.1.1", "2.2.2.2", "3.3.3.3"];

for (var i = 0; i < targets.length; i++) {
    session.pingHost (targets[i], function (error, target) {
        if (! error) {
            console.log (target);
            session.close (); 
        }
    });
}

session.pingHost (target, callback)

The pingHost() method sends a ping request to a remote host.

The target parameter is the dotted quad formatted IP address of the target host for IPv4 sessions, or the compressed formatted IP address of the target host for IPv6 sessions.

The callback function is called once the ping requests is complete. The following arguments will be passed to the callback function:

• error - Instance of the Error class or a sub-class, or null if no error occurred
• target - The target parameter as specified in the request still be the target host and NOT the responding gateway
• sent - An instance of the Date class specifying when the first ping was sent for this request (refer to the Round Trip Time section for more information)
• rcvd - An instance of the Date class specifying when the request completed (refer to the Round Trip Time section for more information)

The following example sends a ping request to a remote host:

var target = "fe80::a00:27ff:fe2a:3427";

session.pingHost (target, function (error, target, sent, rcvd) {
    var ms = rcvd - sent;
    if (error)
        console.log (target + ": " + error.toString ());
    else
        console.log (target + ": Alive (ms=" + ms + ")");
});

session.traceRoute (target, ttl, feedCallback, doneCallback)

The traceRoute() method provides similar functionality to the trace route utility typically provided with most networked operating systems.

The target parameter is the dotted quad formatted IP address of the target host for IPv4 sessions, or the compressed formatted IP address of the target host for IPv6 sessions. The optional ttl parameter specifies the maximum number of hops used by the trace route and defaults to the ttl options parameter as defined by the createSession() method.

Some hosts do not respond to ping requests when the time to live is 0, that is they will not send back an time exceeded error response. Instead of stopping the trace route at the first time out this method will move on to the next hop, by increasing the time to live by 1. It will do this 2 times, meaning that a trace route will continue until the target host responds or at most 3 request time outs are experienced.

Each requst is subject to the retries and timeout option parameters to the createSession() method. That is, requests will be retried per hop as per these parameters.

This method will not call a single callback once the trace route is complete. Instead the feedCallback function will be called each time a ping response is received or a time out occurs. The following arguments will be passed to the feedCallback function:

• error - Instance of the Error class or a sub-class, or null if no error occurred
• target - The target parameter as specified in the request
• ttl - The time to live used in the request which triggered this respinse
• sent - An instance of the Date class specifying when the first ping was sent for this request (refer to the Round Trip Time section for more information)
• rcvd - An instance of the Date class specifying when the request completed (refer to the Round Trip Time section for more information)

Once a ping response has been received from the target, or more than three request timed out errors are experienced, the doneCallback function will be called. The following arguments will be passed to the doneCallback function:

• error - Instance of the Error class or a sub-class, or null if no error occurred
• target - The target parameter as specified in the request

Once the doneCallback function has been called the request is complete and the requestCallback function will no longer be called.

If the feedCallback function returns a true value when called the trace route will stop and the doneCallback will be called.

The following example initiates a trace route to a remote host:

function doneCb (error, target) {
    if (error)
        console.log (target + ": " + error.toString ());
    else
        console.log (target + ": Done");
}

function feedCb (error, target, ttl, sent, rcvd) {
    var ms = rcvd - sent;
    if (error) {
        if (error instanceof ping.TimeExceededError) {
            console.log (target + ": " + error.source + " (ttl="
                    + ttl + " ms=" + ms +")");
        } else {
            console.log (target + ": " + error.toString ()
                    + " (ttl=" + ttl + " ms=" + ms +")");
        }
    } else {
        console.log (target + ": " + target + " (ttl=" + ttl
                + " ms=" + ms +")");
    }
}

session.traceRoute ("192.168.10.10", 10, feedCb, doneCb);

Example Programs

Example programs are included under the modules example directory.

Bugs & Known Issues

None, yet!

Bug reports should be sent to [email protected].

Changes

Version 1.0.0 - 03/02/2013

• Initial release

Version 1.0.1 - 04/02/2013

• Minor corrections to the README.md
• Add note to README.md about error handling
• Timed out errors are now instances of the ping.RequestTimedOutError object

Version 1.0.2 - 11/02/2013

• The RequestTimedOutError class is not being exported

Version 1.1.0 - 13/02/2013

• Support IPv6

Version 1.1.1 - 15/02/2013

• The ping.Session.close() method was not undefining the sessions raw socket after closing
• Return self from the pingHost() method to chain method calls

Version 1.1.2 - 04/03/2013

• Use the raw.Socket.pauseRecv() and raw.Socket.resumeRecv() methods instead of closing a socket when there are no more outstanding requests

Version 1.1.3 - 07/03/2013

• Sessions were limited to sending 65535 ping requests

Version 1.1.4 - 09/04/2013

• Add the packetSize option to the createSession() method to specify how many bytes each ICMP echo request packet should be

Version 1.1.5 - 17/05/2013

• Incorrectly parsing ICMP error responses resulting in responses matching the wrong request
• Use a unique session ID per instance of the Session class to identify requests and responses sent by a session
• Added the (internal) _debugRequest() and _debugResponse() methods, and the _debug option to the createSession() method
• Added example programs ping-ttl.js and ping6-ttl.js
• Use MIT license instead of GPL

Version 1.1.6 - 17/05/2013

• Session IDs are now 2 bytes (previously 1 byte), and request IDs are also now 2 bytes (previously 3 bytes)
• Each ICMP error response now has an associated error class (e.g. the Time exceeded response maps onto the ping.TimeExceededError class)
• Call request callbacks with an error when there are no free request IDs because of too many outstanding requests

Version 1.1.7 - 19/05/2013

• Added the traceRoute() method
• Added the ttl option parameter to the createSession() method, and updated the example programs ping-ttl.js and ping6-ttl.js to use it
• Response callback for pingHost() now includes two instances of the Date class to specify when a request was sent and a response received

Version 1.1.8 - 01/07/2013

• Use raw.Socket.createChecksum() instead of automatic checksum generation

Version 1.1.9 - 01/07/2013

• Use raw.Socket.writeChecksum() instead of manually rendering checksums

Version 1.1.10 - 02/04/2014

• Echo requests sent by this module are processed like responses when sent to the 127.0.0.1 and ::1 addresses

Roadmap

Suggestions and requirements should be sent to [email protected].

License

Copyright (c) 2013 Stephen Vickers

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Author

Stephen Vickers [email protected]