Send EOF on an SSH Channel

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Demonstrates the Chilkat Ssh.ChannelSendEof method, which sends an SSH EOF message on a channel. The only argument is the channel number. EOF closes only the client-to-server direction; the application may still receive stdout, stderr, exit status, EOF, and CLOSE from the server.

Background: Many remote commands read standard input until it ends — wc, sort, cat and friends. Sending EOF is the SSH equivalent of pressing Ctrl+D: it tells the remote process no more input is coming so it can finish and emit results. After sending EOF, do not send more data on that channel; a later send may return true even though nothing is delivered.

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#include <C_CkSsh.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkSsh ssh;
    int sshPort;
    const char *password;
    int channelNum;
    const char *output;

    success = FALSE;

    //  Demonstrates the Ssh.ChannelSendEof method, which sends an SSH EOF message on a channel.  The
    //  only argument is the channel number.  EOF closes only the client-to-server direction; output
    //  may still be received from the server.

    ssh = CkSsh_Create();

    sshPort = 22;
    success = CkSsh_Connect(ssh,"ssh.example.com",sshPort);
    if (success == FALSE) {
        printf("%s\n",CkSsh_lastErrorText(ssh));
        CkSsh_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 = "mySshPassword";

    success = CkSsh_AuthenticatePw(ssh,"mySshLogin",password);
    if (success == FALSE) {
        printf("%s\n",CkSsh_lastErrorText(ssh));
        CkSsh_Dispose(ssh);
        return;
    }

    channelNum = CkSsh_OpenSessionChannel(ssh);
    if (channelNum < 0) {
        printf("%s\n",CkSsh_lastErrorText(ssh));
        CkSsh_Dispose(ssh);
        return;
    }

    success = CkSsh_SendReqExec(ssh,channelNum,"wc -l");
    if (success == FALSE) {
        printf("%s\n",CkSsh_lastErrorText(ssh));
        CkSsh_Dispose(ssh);
        return;
    }

    //  Send input to the remote command.
    success = CkSsh_ChannelSendString(ssh,channelNum,"line one\nline two\nline three\n","utf-8");
    if (success == FALSE) {
        printf("%s\n",CkSsh_lastErrorText(ssh));
        CkSsh_Dispose(ssh);
        return;
    }

    //  Signal that no more input will be sent.  Do not send more data on this channel afterward.
    success = CkSsh_ChannelSendEof(ssh,channelNum);
    if (success == FALSE) {
        printf("%s\n",CkSsh_lastErrorText(ssh));
        CkSsh_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.
    CkSsh_putReadTimeoutMs(ssh,15000);

    //  Output can still be received after EOF is sent.
    success = CkSsh_ChannelReceiveToClose(ssh,channelNum);
    if (success == FALSE) {
        printf("%s\n",CkSsh_lastErrorText(ssh));
        CkSsh_Dispose(ssh);
        return;
    }

    output = CkSsh_getReceivedText(ssh,channelNum,"utf-8");
    if (CkSsh_getLastMethodSuccess(ssh) == FALSE) {
        printf("%s\n",CkSsh_lastErrorText(ssh));
        CkSsh_Dispose(ssh);
        return;
    }

    printf("%s\n",output);

    CkSsh_Disconnect(ssh);


    CkSsh_Dispose(ssh);

    }