Unicode C

Multiple SendReqExec on the Same Connection

Demonstrates running a series of commands on one SSH connection using SendReqExec. Each exec request requires its own logical channel — this is not a separate SSH connection, just a new session channel on the existing one.

Background: An SSH session channel is single-use for an exec request: once the command runs and the server closes the channel, that channel cannot be reused. Opening a fresh channel per command is cheap, since the expensive work — the TCP connection, key exchange, and authentication — is done once and shared. This is why running ten commands over one connection is far faster than connecting ten times.

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Unicode C

#include <C_CkSshW.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkSshW ssh;
    const wchar_t *hostname;
    int port;
    const wchar_t *password;
    int channelNum;
    const wchar_t *cmdOutput;

    success = FALSE;

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

    //  Demonstrates running a series of commands on one SSH connection using SendReqExec.  Each exec
    //  request requires its own logical channel.  This is not a new SSH connection -- it is simply a
    //  new session channel on the existing one.

    ssh = CkSshW_Create();

    hostname = L"ssh.example.com";
    port = 22;
    success = CkSshW_Connect(ssh,hostname,port);
    if (success == FALSE) {
        wprintf(L"%s\n",CkSshW_lastErrorText(ssh));
        CkSshW_Dispose(ssh);
        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.
    password = L"mySshPassword";

    success = CkSshW_AuthenticatePw(ssh,L"mySshLogin",password);
    if (success == FALSE) {
        wprintf(L"%s\n",CkSshW_lastErrorText(ssh));
        CkSshW_Dispose(ssh);
        return;
    }

    //  IMPORTANT: Set a read timeout.  ReadTimeoutMs defaults to 0, which means no limit -- without
    //  it, this call waits forever if the server never sends channel close.
    CkSshW_putReadTimeoutMs(ssh,15000);

    //  ---- 1st command, on its own session channel ----
    channelNum = CkSshW_OpenSessionChannel(ssh);
    if (channelNum < 0) {
        wprintf(L"%s\n",CkSshW_lastErrorText(ssh));
        CkSshW_Dispose(ssh);
        return;
    }

    success = CkSshW_SendReqExec(ssh,channelNum,L"ls -al");
    if (success == FALSE) {
        wprintf(L"%s\n",CkSshW_lastErrorText(ssh));
        CkSshW_Dispose(ssh);
        return;
    }

    success = CkSshW_ChannelReceiveToClose(ssh,channelNum);
    if (success == FALSE) {
        wprintf(L"%s\n",CkSshW_lastErrorText(ssh));
        CkSshW_Dispose(ssh);
        return;
    }

    cmdOutput = CkSshW_getReceivedText(ssh,channelNum,L"utf-8");
    if (CkSshW_getLastMethodSuccess(ssh) == FALSE) {
        wprintf(L"%s\n",CkSshW_lastErrorText(ssh));
        CkSshW_Dispose(ssh);
        return;
    }

    wprintf(L"%s\n",cmdOutput);
    wprintf(L"----\n");

    //  ---- 2nd command, on a NEW session channel over the same connection ----
    channelNum = CkSshW_OpenSessionChannel(ssh);
    if (channelNum < 0) {
        wprintf(L"%s\n",CkSshW_lastErrorText(ssh));
        CkSshW_Dispose(ssh);
        return;
    }

    success = CkSshW_SendReqExec(ssh,channelNum,L"nslookup chilkatsoft.com");
    if (success == FALSE) {
        wprintf(L"%s\n",CkSshW_lastErrorText(ssh));
        CkSshW_Dispose(ssh);
        return;
    }

    success = CkSshW_ChannelReceiveToClose(ssh,channelNum);
    if (success == FALSE) {
        wprintf(L"%s\n",CkSshW_lastErrorText(ssh));
        CkSshW_Dispose(ssh);
        return;
    }

    cmdOutput = CkSshW_getReceivedText(ssh,channelNum,L"utf-8");
    if (CkSshW_getLastMethodSuccess(ssh) == FALSE) {
        wprintf(L"%s\n",CkSshW_lastErrorText(ssh));
        CkSshW_Dispose(ssh);
        return;
    }

    wprintf(L"%s\n",cmdOutput);

    CkSshW_Disconnect(ssh);


    CkSshW_Dispose(ssh);

    }