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Enumerate Active SSH Channel Numbers

Demonstrates the Chilkat Ssh.GetChannelNumber method, which returns the channel number at a zero-based enumeration index in the active channel collection. The only argument is the index — an enumeration position, not itself a channel number. Valid indexes run from 0 through NumOpenChannels - 1, and out-of-range indexes return -1.

Background: One SSH connection can carry many simultaneous channels, and this method lets you walk the live set rather than tracking every channel number yourself. The index-versus-channel-number distinction is the key point: index 0 is simply the first channel in the collection and may well be channel number 3. As channels open and close the enumeration shifts, so treat an index as valid only for the moment you read it.

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const std = @import("std");
const chilkat = @import("chilkat");

pub fn main(init: std.process.Init) !void {
    const alloc = init.arena.allocator();

    // Demonstrates the Ssh.GetChannelNumber method, which returns the channel number at a
    // zero-based enumeration index in the active channel collection.  The only argument is the
    // index, which is an enumeration position and not itself a channel number.

    const ssh = try chilkat.Ssh.init();
    defer ssh.deinit();

    const ssh_port = 22;
    ssh.connect("ssh.example.com", ssh_port) catch {
        std.debug.print("{s}\n", .{try ssh.getLastErrorText(alloc)});
        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 password = "mySshPassword";

    ssh.authenticatePw("mySshLogin", password) catch {
        std.debug.print("{s}\n", .{try ssh.getLastErrorText(alloc)});
        return;
    };

    // Open a couple of channels so the collection has more than one entry.
    const channel_a = ssh.openSessionChannel();
    if (channel_a < 0) {
        std.debug.print("{s}\n", .{try ssh.getLastErrorText(alloc)});
        return;
    }

    const channel_b = ssh.openSessionChannel();
    if (channel_b < 0) {
        std.debug.print("{s}\n", .{try ssh.getLastErrorText(alloc)});
        return;
    }

    // Enumerate the active channels.  Valid indexes are 0 through NumOpenChannels - 1.
    const n = ssh.getNumOpenChannels();
    std.debug.print("Open channels: {d}\n", .{n});
    var i: i32 = 0;
    i = 0;
    while (i < n) : (i += 1) {
        const ch_num = ssh.getChannelNumber(i);
        std.debug.print("Index {d} is channel number {d}\n", .{ i, ch_num });
    }

    ssh.disconnect();
}