C++

Check Whether an SSH Channel is Open

Demonstrates the Chilkat Ssh.ChannelIsOpen method, which reports whether a channel number identifies a channel Chilkat currently considers open for application I/O. The only argument is the channel number. This example checks the channel before and after sending CLOSE.

Background: Because one SSH connection can carry many channels with independent lifetimes, code that manages several needs a way to ask whether a given one is still usable. This returns false for invalid or nonexistent channel numbers, after a local Disconnect, once remote closure is processed, and immediately after ChannelSendClose — which marks the channel locally closed without waiting for the remote side.

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C++

#include <CkSsh.h>

void ChilkatSample(void)
    {
    bool success = false;

    //  Demonstrates the Ssh.ChannelIsOpen method, which reports whether a channel number identifies
    //  a channel Chilkat currently considers open for application I/O.  The only argument is the
    //  channel number.

    CkSsh ssh;

    int sshPort = 22;
    success = ssh.Connect("ssh.example.com",sshPort);
    if (success == false) {
        std::cout << ssh.lastErrorText() << "\r\n";
        return;
    }

    //  Normally you would not hard-code the password in source.  You should instead obtain it
    //  from an interactive prompt, environment variable, or a secrets vault.
    const char *password = "mySshPassword";

    success = ssh.AuthenticatePw("mySshLogin",password);
    if (success == false) {
        std::cout << ssh.lastErrorText() << "\r\n";
        return;
    }

    //  Open a session channel.  A negative return value indicates failure.
    int channelNum = ssh.OpenSessionChannel();
    if (channelNum < 0) {
        std::cout << ssh.lastErrorText() << "\r\n";
        return;
    }

    if (ssh.ChannelIsOpen(channelNum)) {
        std::cout << "The channel is open." << "\r\n";
    }
    else {
        std::cout << "The channel is not open." << "\r\n";
    }

    //  Send CLOSE, which immediately marks the channel locally closed.
    success = ssh.ChannelSendClose(channelNum);
    if (success == false) {
        std::cout << ssh.lastErrorText() << "\r\n";
        return;
    }

    if (ssh.ChannelIsOpen(channelNum)) {
        std::cout << "Still open." << "\r\n";
    }
    else {
        std::cout << "The channel is now closed." << "\r\n";
    }

    ssh.Disconnect();
    }