(Objective-C) TCP or TLS over Multiple Hop SSH to Remote Server

Demonstrates how to use the Chilkat Socket API to connect to a remote server (using TCP or TLS) tunneled through mulitple-hop SSH. The scheme looks like this:

Application => ServerSSH1 => ServerSSH2 => DestinationServer

The ConnectThroughSsh and UseSsh methods are added in Chilkat version 9.5.0.55 to accomplish this task.

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#import <CkoSsh.h>
#import <CkoSocket.h>
#import <NSString.h>

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

CkoSsh *ssh1 = [[CkoSsh alloc] init];

// Connect directly to the 1st SSH server.
BOOL success = [ssh1 Connect: @"serverssh1.com" port: [NSNumber numberWithInt: 22]];
if (success != YES) {
    NSLog(@"%@",ssh1.LastErrorText);
    return;
}

// Authenticate using login/password:
success = [ssh1 AuthenticatePw: @"ssh1Login" password: @"ssh1Password"];
if (success != YES) {
    NSLog(@"%@",ssh1.LastErrorText);
    return;
}

// Connect through the 1st SSH connection to reach a 2nd SSH server.
// Note: Any number of SSH connections may be simultaneously tunneled through a single
// existing SSH connection.
CkoSsh *ssh2 = [[CkoSsh alloc] init];
success = [ssh2 ConnectThroughSsh: ssh1 hostname: @"serverssh2.com" port: [NSNumber numberWithInt: 22]];
if (success != YES) {
    NSLog(@"%@",ssh2.LastErrorText);
    return;
}

// Authenticate with ssh2...
success = [ssh2 AuthenticatePw: @"ssh2Login" password: @"ssh2Password"];
if (success != YES) {
    NSLog(@"%@",ssh2.LastErrorText);
    return;
}

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

// Tell the socket object to connect to our destination server though the ssh2 tunnel (which itself is routed through ssh1).
// The connection looks like this:  ApplicationSocket(TLS) => ServerSSH1 => ServerSSH2 => DestinationServer
success = [socket UseSsh: ssh2];
if (success != YES) {
    NSLog(@"%@",socket.LastErrorText);
    return;
}

// Connect using TLS to www.chilkatsoft.com
// We could also tunnel a bare TCP connection by specifying port 80 with useTls = NO.
BOOL useTls = YES;
int maxWaitMillisec = 20000;
success = [socket Connect: @"www.chilkatsoft.com" port: [NSNumber numberWithInt: 443] ssl: useTls maxWaitMs: [NSNumber numberWithInt: maxWaitMillisec]];
if (success != YES) {
    NSLog(@"%@",socket.LastErrorText);
    return;
}

// Once the multiple hop SSH tunneled connection is setup,  the socket programming
// is identical to the normal case where we have a direct connection.

// Tell the socket object that all text is to be sent in the utf-8 encoding,
// and the text received is assumed to be utf-8.
socket.StringCharset = @"utf-8";

// Send an HTTP HEAD request:
success = [socket SendString: @"HEAD / HTTP/1.1\r\nHost: www.chilkatsoft.com\r\n\r\n"];
if (success != YES) {
    NSLog(@"%@",socket.LastErrorText);
    return;
}

// Wait a maximum of 4 seconds while no data is forthcoming:
socket.MaxReadIdleMs = [NSNumber numberWithInt:4000];

// Get the 1st response line, which should be "HTTP/1.1 200 OK"
NSString *responseStatusLine = [socket ReceiveToCRLF];
if (socket.LastMethodSuccess != YES) {
    NSLog(@"%@",socket.LastErrorText);
    return;
}

NSLog(@"%@%@",@"StatusLine: ",responseStatusLine);

// Now get the 1st line of the response header:
NSString *responseHeaderLine = [socket ReceiveToCRLF];
if (socket.LastMethodSuccess != YES) {
    NSLog(@"%@",socket.LastErrorText);
    return;
}

NSLog(@"%@%@",@"HeaderLine: ",responseHeaderLine);

// Now read the remainder of the response header by reading until a double CRLF is seen:
NSString *remainderOfHeader = [socket ReceiveUntilMatch: @"\r\n\r\n"];
if (socket.LastMethodSuccess != YES) {
    NSLog(@"%@",socket.LastErrorText);
    return;
}

NSLog(@"%@%@",@"Remainder: ",remainderOfHeader);

// Close the connection with the server.  This closes the tunnel through ssh2.
// Wait a max of 20 seconds (20000 millsec)
success = [socket Close: [NSNumber numberWithInt: 20000]];

// Close the connection with ssh2.  (This closes the the tunnel through ssh1.)
// The connection with ssh1 is still alive, and may be used for more connections.
[ssh2 Disconnect];

[ssh1 Disconnect];