Lua

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.

Chilkat Lua Downloads

Download Chilkat for Lua

Lua

local chilkat = require("chilkat")

local socket = chilkat.Socket.new()

-- Connect to the server using TLS.
local bTls = true
local maxWaitMs = 5000
local success = socket:connect("example.com", 5000, bTls, maxWaitMs)
if not success then
    print(socket.last_error_text)
    return
end

-- Read a four-byte length prefix as a signed 32-bit integer (network byte order by default).  A
-- return value of -1 indicates failure.
local messageLength = socket:receive_count()
if messageLength < 0 then
    print(socket.last_error_text)
    return
end

print("The peer will send " .. messageLength .. " bytes.")