echoclient

#!/usr/bin/env lua5.1
--[[
An example RPC-like echo client.
See ECHO.txt for usage.

echoclient host ctrl_port string1 string2....
   request one port
   connect to requested port
   send/receive each string in turn
   close echo port
   close control port
]]

require"socket"

local host = arg[1]
local ctrl_port = arg[2]

if #arg < 3 then
    print("Usage: " .. arg[0] .. " host ctrl_port string1 [string2 string3 ...]")
    os.exit(0)
end

function connect(host, port)
    local s = socket.tcp()
    assert(s:settimeout(5))
    assert(s:connect(host, port))
    print("Connected to:", host, port, "from", s:getsockname())
    return s
end

local function get_echo_port(ctrl_sock)
    print"Get port..."
    assert(ctrl_sock:send("GET\n"))
    local port = assert(ctrl_sock:receive())
    print("Got port:", port)
    return tonumber(port)
end

local function send_strings(host, port)
    print("Connect to echo port:", host, port)
    local s = connect(host, port)
    for i = 3, #arg do
        print(i, "Send:", arg[i])
        assert(s:send(arg[i].."\n"))
        local data, err = assert(s:receive())
        print(i, "Recv:", data)
    end
    return s
end

local function pause()
    os.execute"sleep 1" -- pause so conntrack -L can show the expectations
end

print("Connect to broker...")

local ctrl_sock = connect(host, ctrl_port)

echo_port = get_echo_port(ctrl_sock)

ctrl_sock:close()

echo_sock1 = send_strings(host, echo_port, "first")

pause()

echo_sock2 = send_strings(host, echo_port, "second")

echo_sock2:close()
echo_sock1:close()

--[[
print("Use echo port as long as we can...")

while send_strings(host, echo_port, "... as long as we can") do
    pause()
end
--]]