Objective-C

WebSocket through SSH Tunnel

See more WebSocket Examples

This example shows how to establish a WebSocket connection through an SSH tunnel. The WebSocket protocol communications will be encapsulated within an SSH tunnel. Objective-C

#import <CkoSocket.h>
#import <NSString.h>
#import <CkoRest.h>
#import <CkoWebSocket.h>

BOOL success = NO;

// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

// --------------------------------------------------
// This example borrows the code from the REST through SSH Tunnel example.
// We first use the Chilkat Socket object to establish a connection to the WebSocket server through an SSH Tunnel.
// Next, the Rest object uses the Socket object for its connection.
// Finally, the WebSocket object uses the Rest object for its connection.  
// 
// Hopefully the flexibility of this architecture is easy to see.  All of the HTTP functionality of the Rest object,
// such as HTTP authentication, custom headers, etc. is available to the WebSocket.  Likewise, all of the advanced functionality
// of the Socket object is in turn available to the Rest object.  

// The high-level steps for accomplishing the task of running the WebSocket protocol through an SSH accomplished as follows:
// 1) Create the SSH tunnel using Chilkat Socket.
// 2) Open a port-forwarding channel (to the WebSocket server) within the tunnel.
// 2) Tell Rest to use the Socket object.
// 3) Tell WebSocket to use the Rest object.

CkoSocket *tunnel = [[CkoSocket alloc] init];

NSString *sshHostname = @"sftp.example.com";
int sshPort = 22;

// Connect to an SSH server and establish the SSH tunnel:
success = [tunnel SshOpenTunnel: sshHostname sshPort: [NSNumber numberWithInt: sshPort]];
if (success == NO) {
    NSLog(@"%@",tunnel.LastErrorText);
    return;
}

// Authenticate with the SSH server via a login/password
// or with a public key.
// This example demonstrates SSH password authentication.
success = [tunnel SshAuthenticatePw: @"mySshLogin" sshPassword: @"mySshPassword"];
if (success == NO) {
    NSLog(@"%@",tunnel.LastErrorText);
    return;
}

//  OK, the SSH tunnel is setup.  Now open a channel within the tunnel.

BOOL bTls = YES;
int port = 443;
int maxWaitMs = 5000;

// This returns a socket object that is a single channel within the SSH tunnel.
// The SSH channel is our logical port-forwarded connection through the SSH tunnel.
// Note: This example establishes a TLS connection to the target WebSocket server.
// (The TLS protocol will run on the logical channel within the SSH tunnel.)
// Your application can just as easily make a non-TLS connection by changing the arguments
// passed to SshNewChannel.
CkoSocket *channel = [[CkoSocket alloc] init];
success = [tunnel SshNewChannel: @"some-websocket-server.com" port: [NSNumber numberWithInt: port] ssl: bTls maxWaitMs: [NSNumber numberWithInt: maxWaitMs] channel: channel];
if (success == NO) {
    NSLog(@"%@",tunnel.LastErrorText);
    return;
}

// Create a REST object and tell it to use the SSH channel.
// This connection is a TLS running on an SSH channel through an SSH tunnel.
// In other words, TLS is wrapped within the SSH tunnel.
CkoRest *rest = [[CkoRest alloc] init];
success = [rest UseConnection: channel autoReconnect: NO];
if (success == NO) {
    NSLog(@"%@",rest.LastErrorText);
    return;
}

// Finally, tell our WebSocket object to use the Rest object..
CkoWebSocket *ws = [[CkoWebSocket alloc] init];

// Tell the WebSocket to use this connection.
success = [ws UseConnection: rest];
if (success == NO) {
    NSLog(@"%@",ws.LastErrorText);
    return;
}

// Add the standard WebSocket open handshake headers that will be needed.
// (This adds the required HTTP request headers to the rest object.)
[ws AddClientHeaders];

// Add any additional headers that might be desired.
// Two common WebSocketSpecific headers are "Sec-WebSocket-Protocol" and "Origin".
[rest AddHeader: @"Sec-WebSocket-Protocol" value: @"x-some-websocket-subprotocol"];
[rest AddHeader: @"Origin" value: @"http://some-websocket-server.com"];

// Do the open handshake.
NSString *responseBody = [rest FullRequestNoBody: @"GET" uriPath: @"/something"];
if (rest.LastMethodSuccess == NO) {
    NSLog(@"%@",rest.LastErrorText);
    return;
}

// If successful, the HTTP response status code should be 101,
// and the response body will be empty. (If it failed, we'll have a look
// at the response body..)
int statusCode = [rest.ResponseStatusCode intValue];
NSLog(@"%@%d",@"Response status code: ",statusCode);

if (statusCode != 101) {
    NSLog(@"%@",responseBody);
    NSLog(@"%@",@"-- Failed because of unexpected response status code.");
    return;
}

// We have the expected 101 response, so let's now validate the 
// contents of the response, such as the value sent by the server in the
// Sec-WebSocket-Accept header. 
success = [ws ValidateServerHandshake];
if (success == NO) {
    NSLog(@"%@",ws.LastErrorText);
    return;
}

NSLog(@"%@",@"WebSocket connection successful.");

// The application may now begin sending and receiving frames on the WebSocket connection.
// (At this point, we're done with the rest object...)