(Objective-C) SSH -- Running Commands that Prompt for Additional Input, such as "su"

Demonstrates how to run a shell command via SSH where the shell command prompts for additional input from the client. This example demonstrates "su".

Chilkat Objective-C Library Downloads MAC OS X (Cocoa) Libs iOS Libs

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

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

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

// Hostname may be an IP address or hostname:
NSString *hostname = @"172.16.16.46";
int port = 22;

BOOL success = [ssh Connect: hostname port: [NSNumber numberWithInt: port]];
if (success != YES) {
    NSLog(@"%@",ssh.LastErrorText);
    return;
}

// If receiving output from a command stalls for more than 5 seconds, then stop waiting.
ssh.IdleTimeoutMs = [NSNumber numberWithInt:5000];

success = [ssh AuthenticatePw: @"myLogin" password: @"myPassword"];
if (success != YES) {
    NSLog(@"%@",ssh.LastErrorText);
    return;
}

// Open a session channel. 
int channelNum = [[ssh OpenSessionChannel] intValue];
if (channelNum < 0) {
    NSLog(@"%@",ssh.LastErrorText);
    return;
}

// Request a pseudo-terminal
NSString *termType = @"dumb";
int widthInChars = 120;
int heightInChars = 40;
int pixWidth = 0;
int pixHeight = 0;
success = [ssh SendReqPty: [NSNumber numberWithInt: channelNum] xTermEnvVar: termType widthInChars: [NSNumber numberWithInt: widthInChars] heightInRows: [NSNumber numberWithInt: heightInChars] pixWidth: [NSNumber numberWithInt: pixWidth] pixHeight: [NSNumber numberWithInt: pixHeight]];
if (success != YES) {
    NSLog(@"%@",ssh.LastErrorText);
    return;
}

// Start a shell on the channel:
success = [ssh SendReqShell: [NSNumber numberWithInt: channelNum]];
if (success != YES) {
    NSLog(@"%@",ssh.LastErrorText);
    return;
}

// Send the su command.
// (The SSH server I'm using for testing is a Linux Ubuntu
// system running OpenSSH.  It is important in this case to send a bare-LF
// and not a CRLF.)
NSString *cmd = @"su\n";
success = [ssh ChannelSendString: [NSNumber numberWithInt: channelNum] strData: cmd charset: @"ansi"];
if (success != YES) {
    NSLog(@"%@",ssh.LastErrorText);
    return;
}

// Read until we get the prompt for the password:
success = [ssh ChannelReceiveUntilMatch: [NSNumber numberWithInt: channelNum] matchPattern: @"Password:" charset: @"ansi" caseSensitive: YES];
if (success != YES) {
    NSLog(@"%@",ssh.LastErrorText);
    return;
}

// Display what we've received so far:
NSLog(@"%@",[ssh GetReceivedText: [NSNumber numberWithInt: channelNum] charset: @"ansi"]);

// Send the password. (This is the equivalent of typing at the shell prompt.)
// Again, make sure it uses a bare-LF and not a CRLF.
NSString *password = 0;
password = @"myPassword\n";
success = [ssh ChannelSendString: [NSNumber numberWithInt: channelNum] strData: password charset: @"ansi"];
if (success != YES) {
    NSLog(@"%@",ssh.LastErrorText);
    return;
}

// Read the response until we get the shell prompt (assuming it's successful)
// In my case, the shell prompt is: "chilkat@vivoMini64:~$ "
NSString *myShellPrompt = @"chilkat@vivoMini64:~$";
// It will be different in your case.
success = [ssh ChannelReceiveUntilMatch: [NSNumber numberWithInt: channelNum] matchPattern: myShellPrompt charset: @"ansi" caseSensitive: YES];
if (success != YES) {
    // Check the last-error information and the session log...
    NSLog(@"%@",ssh.LastErrorText);
    // Check to see what was received.  
    NSLog(@"%@",[ssh GetReceivedText: [NSNumber numberWithInt: channelNum] charset: @"ansi"]);
    return;
}

// Display what we've received so far.  This clears
// the internal receive buffer, which is important. 
// After we send the command, we'll be reading until
// the next command prompt.  If the command prompt
// is already in the internal receive buffer, we'll think we're
// already finished...
NSLog(@"%@",[ssh GetReceivedText: [NSNumber numberWithInt: channelNum] charset: @"ansi"]);

// Send a command.  In this case, we are sending the "ls" command:
cmd = @"ls\n";
success = [ssh ChannelSendString: [NSNumber numberWithInt: channelNum] strData: cmd charset: @"ansi"];
if (success != YES) {
    NSLog(@"%@",ssh.LastErrorText);
    return;
}

// Read until the next command prompt:
success = [ssh ChannelReceiveUntilMatch: [NSNumber numberWithInt: channelNum] matchPattern: myShellPrompt charset: @"ansi" caseSensitive: YES];
if (success != YES) {
    // Check the last-error information and the session log...
    NSLog(@"%@",ssh.LastErrorText);
    // Check to see what was received.  
    NSLog(@"%@",[ssh GetReceivedText: [NSNumber numberWithInt: channelNum] charset: @"ansi"]);
    return;
}

// Display the command output:
NSLog(@"%@",[ssh GetReceivedText: [NSNumber numberWithInt: channelNum] charset: @"ansi"]);

// You may continue sending additional commands.
// The technique is: send the command, read until the next command prompt,
// and then fetch/clear the internal receive buffer.

// We're done, so shut it down..

// Send an EOF.  This tells the server that no more data will 
// be sent on this channel.  The channel remains open, and
// the SSH client may still receive output on this channel.
success = [ssh ChannelSendEof: [NSNumber numberWithInt: channelNum]];
if (success != YES) {
    NSLog(@"%@",ssh.LastErrorText);
    return;
}

// Close the channel:
success = [ssh ChannelSendClose: [NSNumber numberWithInt: channelNum]];
if (success != YES) {
    NSLog(@"%@",ssh.LastErrorText);
    return;
}

// Disconnect
[ssh Disconnect];