Zig

Receive a 4-byte Length Prefix from a Socket

Demonstrates Socket.ReceiveCount, which reads a four-byte length prefix as a signed 32-bit integer. A return value of -1 indicates failure.

Background. Reading the length prefix first tells the application exactly how many bytes to read for the message body, which is a reliable way to know when a full message has arrived.

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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();

    const socket = try chilkat.Socket.init();
    defer socket.deinit();

    // Connect to the server using TLS.
    const b_tls = true;
    const max_wait_ms = 5000;
    socket.connect("example.com", 5000, b_tls, max_wait_ms) catch {
        std.debug.print("{s}\n", .{try socket.getLastErrorText(alloc)});
        return;
    };

    // Read a four-byte length prefix as a signed 32-bit integer (network byte order by default).  A
    // return value of -1 indicates failure.
    const message_length = socket.receiveCount();
    if (message_length < 0) {
        std.debug.print("{s}\n", .{try socket.getLastErrorText(alloc)});
        return;
    }

    std.debug.print("The peer will send {d} bytes.\n", .{message_length});
}