I want to build a radio server in Elixir, my current code using plug & cowboy (thank to #rozap) stream an audio file to a browser client
defmodule Plugtest do
import Plug.Conn
#chunk_size 128
#song_path "./song.mp3"
#content_type "audio/mpeg"
#status_code 200
def init(opts), do: opts
def call(conn, opts) do
conn = conn
|> send_chunked(#status_code)
|> put_resp_content_type(#content_type)
File.stream!(#song_path, [], #chunk_size)
|> Enum.into(conn)
end
end
IO.puts "streaming # http://localhost:4000"
Plug.Adapters.Cowboy.http Plugtest, []
I want this server to work and play the songs from a playlist
( for this test looping song.mp3 is fine )
and save the current chunk so each new user will listen from this chunk
and that will make all users hear from the same second, like a regular radio server, how can I make this happen ?
Related
I use Raspberry Pi Pico with ESP8266 WiFi module, and I am trying to write a TCP client. Rasp Pi Pico is able to send AT commands and receive responses and send data through UART. Also the TCP client is able to send data to the TCP server, which runs in my laptop. However the problem is that the client is not able to connect to the server after some point.
Let me first show the server-side code. In server, I am trying to receive data basically. ConnectionResetError was a problem for me so I wrote the following except block. I am not sure it is buggy or not, since I'm kind of a noob in this area.
import socket
HOST = ""
PORT = 8080
mysocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
mysocket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
mysocket.bind((HOST, PORT))
mysocket.listen(1)
while True:
print("Waiting...")
conn, addr = mysocket.accept()
print('[SERVER] - Connected from: %s' % str(addr))
while True:
try:
request = conn.recv(1024)
if not request:
break
conn.sendall(request.upper())
print('[SERVER] - Received Data: %s' % str(request))
except ConnectionResetError as cr_err:
break
conn.close()
print("[SERVER] - Disconnected")
Here is my client-side code. In client, I wrote two helper classes called ESP8266 and Sensor, in which I control the WiFi module and read analog value from a sensor. Pico first tries to start WiFi module, afterwards it tries to connect to TCP server and send data. After some point it does not connect to the TCP server, so it restart the WiFi module and reconnects.
class EndDevice:
def __init__(self, sensor_id):
self.__wifi_module = ESP8266(UART_PIN, BAUDRATE)
self.__sensor = Sensor(sensor_id, SENSOR_PIN)
def start(self):
self.__wifi_module.start()
self.__wifi_module.set_mode(STATION_MODE)
self.__wifi_module.join_access_point(AP_NAME, AP_PWD)
def reconnect(self):
self.__wifi_module.restart()
self.__wifi_module.set_mode(STATION_MODE)
self.__wifi_module.join_access_point(AP_NAME, AP_PWD)
def run(self):
retry_count = 0
while True:
if self.__wifi_module.start_connection("TCP", SERVER_HOST, SERVER_PORT):
self.__wifi_module.send_data(
str(self.__sensor.generate_package()))
self.__wifi_module.close_connection()
else:
retry_count += 1
if retry_count == MAX_RETRY:
break
if __name__ == "__main__":
pico = EndDevice("SM-0")
pico.start()
while True:
pico.run()
pico.reconnect()
Finally I will share some of the methods in classes ESP8266 and UARTHandler (which is used in ESP8266), so you can see if I do anything non-sense.
start_connection method in ESP8266 is as follows. In this method, I tried to send the corresponding AT command to connect to a TCP server. In the method self.__uart_handler.send_receive_cmd timeout duration is 2000ms, and other parameters are AT command, connection_type (TCP), server IP address and server port, in order.
def start_connection(self, conn_type, remote_ip, remote_port):
conn_type, remote_ip = "\"{}\"".format(conn_type), "\"{}\"".format(remote_ip)
response = self.__uart_handler.send_receive_cmd(2000, CONN_START, conn_type, remote_ip, str(remote_port))
if "OK" in response:
self.__log("Connected to {} at port {}.".format(remote_ip, remote_port))
return True
else:
self.__log("Failed to create a connection with {} at port {}.".format(remote_ip, remote_port))
return False
send_receive_cmd method in UARTHandler is as follows. In this method I use lots of helper methods as you can see, however they are just formatting and writing to UART or reading from UART. I also insert a timeout between UART-read and UART-write
def __generate_cmd(self, cmd, *args):
if len(args) != 0:
cmd += "="
for idx, each in enumerate(args):
cmd += str(each)
if idx != len(args)-1:
cmd += ","
cmd += "\r\n"
return cmd
def __send_cmd(self, cmd, *args):
sent_cmd = self.__generate_cmd(cmd, *args)
self.__uart.write(sent_cmd)
def __receive_response(self, cmd):
response = self.__uart.read()
try: return response.decode('utf-8')
except: return response
def send_receive_cmd(self, timeout, cmd, *args):
self.__send_cmd(cmd, *args)
utime.sleep_ms(timeout)
return self.__receive_response(self.__generate_cmd(cmd, *args))
Let me ask my question again. This codes are working properly in starting-restarting and sending data for (let me say) 3 connections. However, after some connect-disconnect later, TCP client is not able to make a connection with TCP server. Again after some failed connection attempt, WiFi module is restarted and TCP connection is made and working properly again.
I'm trying make authorization/authentication graphql subscriptions with elixir and absinthe using cookies and I used the follow link:
https://nts.strzibny.name/graphql-subscriptions-with-elixir-and-absinth/
I'm trying authenticate the user for subscribe the right topic but I don't have access to the cookies in the subscription connection. Why?
After I saw the follow link:
https://hexdocs.pm/absinthe_phoenix/Absinthe.Phoenix.Socket.html
And in my user_socket.ex I pass the user_id as query param, this works, but it's not secure at all... I can pass the id that I want ??!!
Can someone help me?
#moduledoc false
use Phoenix.Socket
use Absinthe.Phoenix.Socket,
schema: MyAppGraphQL.Schema
## Channels
# channel "room:*", MyAppWeb.RoomChannel
# Socket params are passed from the client and can
# be used to verify and authenticate a user. After
# verification, you can put default assigns into
# the socket that will be set for all channels, ie
#
# {:ok, assign(socket, :user_id, verified_user_id)}
#
# To deny connection, return `:error`.
#
# See `Phoenix.Token` documentation for examples in
# performing token verification on connect.
def connect(%{"user_id" => user_id}, socket) do
case current_user(user_id) do
nil ->
:error
current_user ->
socket =
Absinthe.Phoenix.Socket.put_options(socket,
context: %{
current_user: current_user
}
)
{:ok, socket}
end
end
def connect(_, _), do: :error
defp current_user(user_id), do: MyApp.Accounts.lookup_user_with_company(user_id)
# Socket id's are topics that allow you to identify all sockets for a given user:
#
# def id(socket), do: "user_socket:#{socket.assigns.user_id}"
#
# Would allow you to broadcast a "disconnect" event and terminate
# all active sockets and channels for a given user:
#
# MyAppWeb.Endpoint.broadcast("user_socket:#{user.id}", "disconnect", %{})
#
# Returning `nil` makes this socket anonymous.
def id(_socket), do: nil
end```
I'm trying to write a very basic webserver in Haskell. This is my code:
{-# LANGUAGE OverloadedStrings #-}
import Network (withSocketsDo, listenOn, PortID(..))
import Network.Socket (Socket, accept, close, setSocketOption, SocketOption(..))
import Network.Socket.ByteString (send, sendAll, recv)
import Control.Concurrent.Async (async)
import Control.Monad (forever)
import Data.ByteString.Char8 (unpack)
import Request
main = withSocketsDo $ do
sock <- listenOn $ PortNumber 3000
putStrLn "Listening on port 3000..."
forever $ do
(conn, _) <- accept sock
async $ handleAccept conn
handleAccept :: Socket -> IO ()
handleAccept sock = do
putStrLn $ "Connected!"
rawReq <- recv sock 4096
let req = parseRawRequest $ unpack rawReq -- returns Maybe Request
putStrLn $ show req
handleRequest sock req
handleRequest :: Socket -> Maybe Request -> IO ()
handleRequest sock Nothing = do
putStrLn "Closing..."
handleRequest sock req = do
sendAll sock "In handleRequest!" -- Doesn't appear until server is killed.
This is what I expected to happen:
Start server.
"Listening on port 3000..." is printed on server-side.
Do curl localhost:3000
"Connected!" is printed server-side.
The request is printed server-side.
"In handleRequest!" is printed.
What actually happens:
Start server.
"Listening on port 3000..." is printed on server-side.
Do curl localhost:3000
"Connected!" is printed server-side.
The request is printed server-side.
I wait patiently
I kill the server with CTRL+C
"In handleRequest!" prints client-side.
I suspect this has something to do with possible laziness in recv, although I use the value immediately afterwards (I parse the raw request into a Request type), so theoretically it should be evaluated.
If I put sendAll sock "Yadda yadda at the end of handleAccept, everything works fine. It's when I move this behaviour into a new function, handleRequest, that things go wonky.
Any thoughts? I'm new-ish to Haskell, so I'd appreciate any comments on the issue, or my code generally.
Cheers.
EDIT:
This is super weird! I "fixed" it, but I have no idea why this occurs.
This is the line that only appeared after I killed the server:
handleRequest sock req = do
sendAll sock "In handleRequest!" -- Doesn't appear until server is killed.
If I intentionally close the socket after sending, it works:
handleRequest sock req = do
sendAll sock "In handleRequest!" -- Now appears without killing the server
close sock
So it sends when the connection is closed. This is consistent with previous behaviour, since the connection automatically closes when the server is killed.
Now for the confusing bit. If I replace it with:
handleRequest sock req = do
sendAll sock "In handleRequest!\n" -- Works perfect
This works without closing the connection! It does what I expected, just by adding a newline. Why does this occur?
What on earth? Is it a printing problem with my terminal, not the code? (OSX iTerm2)
EDIT 2:
Was asked to provide the code for my Request module:
import Data.List (isInfixOf)
import Data.List.Split (splitOn)
data RequestType = GET | PUT
deriving Show
data Request =
Request {
reqType :: RequestType,
path :: String,
options :: [(String, String)]
} deriving Show
-- Turn a raw HTTP request into a request
-- object.
parseRawRequest :: String -> Maybe Request
parseRawRequest rawReq =
Request <$> parseRawRequestType rawReq
<*> parseRawRequestPath rawReq
<*> parseRawRequestOps rawReq
-- Turn an (entire) raw HTTP request into just
-- the request type.
parseRawRequestType :: String -> Maybe RequestType
parseRawRequestType rawReq =
case typ of
"GET" -> Just GET
"PUT" -> Just PUT
_ -> Nothing
where typ = (head . words . head . lines) rawReq
-- Turn an (entire) raw HTTP request into just
-- the path.
parseRawRequestPath :: String -> Maybe String
parseRawRequestPath = Just . (!! 1) . words . head . lines
-- Turn an (entire) raw HTTP request into just
-- a lookup table of their options.
parseRawRequestOps :: String -> Maybe [(String, String)]
parseRawRequestOps rawReq = Just [("One", "Two")] -- Test impl
I have one answer and one suggestion.
The suggestion is for you to turn off the naggle algorithm after accept:
setSocketOption conn NoDelay 1
The answer is that your sendAll is sending data but curl is not printing it. You can confirm this with netcat, for example. I commented out your Nothing case so that no matter what I typed in netcat I was sure to get the "In handleRequest!" message back:
server:
% ghc so.hs && ./so
Listening on port 3000...
Connected!
Nothing
client:
% nc localhost 3000
test ; My input, with a newline
In handleRequest! ; Printed out, no newline
Alternatively, you can use curl's -N option to disable buffering.
% curl -N localhost:3000
In handleRequest!
I met an error when running codes at the bottom. It's like a simple ftp.
I use python2.6.6 and CentOS release 6.8
In most linux server, it gets right results like this:(I'm very sorry that I have just sign up and couldn't )
Clinet:
[root#Test ftp]# python client.py
path:put|/home/aaa.txt
Server:
[root#Test ftp]# python server.py
connected...
pre_data:put|aaa.txt|4
cmd: put
file_name: aaa.txt
file_size: 4
upload successed.
But I get errors in some server(such as my own VM in my PC). I have done lots of tests(python2.6/python2.7, Centos6.5/Centos6.7) and found this error is not because them. Here is the error imformation:
[root#Lewis-VM ftp]# python server.py
connected...
pre_data:put|aaa.txt|7sdfsdf ###Here gets the wrong result, "sdfsdf" is the content of /home/aaa.txt and it shouldn't be sent here to 'file_size' and so it cause the "ValueError" below
cmd: put
file_name: aaa.txt
file_size: 7sdfsdf
----------------------------------------
Exception happened during processing of request from ('127.0.0.1', 10699)
Traceback (most recent call last):
File "/usr/lib64/python2.6/SocketServer.py", line 570, in process_request_thread
self.finish_request(request, client_address)
File "/usr/lib64/python2.6/SocketServer.py", line 332, in finish_request
self.RequestHandlerClass(request, client_address, self)
File "/usr/lib64/python2.6/SocketServer.py", line 627, in __init__
self.handle()
File "server.py", line 30, in handle
if int(file_size)>recv_size:
ValueError: invalid literal for int() with base 10: '7sdfsdf\n'
What's more, I found that if I insert a time.sleep(1) between sk.send(cmd+"|"+file_name+'|'+str(file_size)) and sk.send(data) in client.py, the error will disappear. I have said that I did tests in different system and python versions and the error is not because them. So I guess that is it because of some system configs? I have check about socket.send() and socket.recv() in python.org but fount nothing helpful. So could somebody help me to explain why this happend?
The code are here:
#!/usr/bin/env python
#coding:utf-8
################
#This is server#
################
import SocketServer
import os
class MyServer(SocketServer.BaseRequestHandler):
def handle(self):
base_path = '/home/ftp/file'
conn = self.request
print 'connected...'
while True:
#####receive pre_data: we should get data like 'put|/home/aaa|7'
pre_data = conn.recv(1024)
print 'pre_data:' + pre_data
cmd,file_name,file_size = pre_data.split('|')
print 'cmd: ' + cmd
print 'file_name: '+ file_name
print 'file_size: '+ file_size
recv_size = 0
file_dir = os.path.join(base_path,file_name)
f = file(file_dir,'wb')
Flag = True
####receive 1024bytes each time
while Flag:
if int(file_size)>recv_size:
data = conn.recv(1024)
recv_size+=len(data)
else:
recv_size = 0
Flag = False
continue
f.write(data)
print 'upload successed.'
f.close()
instance = SocketServer.ThreadingTCPServer(('127.0.0.1',9999),MyServer)
instance.serve_forever()
#!/usr/bin/env python
#coding:utf-8
################
#This is client#
################
import socket
import sys
import os
ip_port = ('127.0.0.1',9999)
sk = socket.socket()
sk.connect(ip_port)
while True:
input = raw_input('path:')
#####we should input like 'put|/home/aaa.txt'
cmd,path = input.split('|')
file_name = os.path.basename(path)
file_size=os.stat(path).st_size
sk.send(cmd+"|"+file_name+'|'+str(file_size))
send_size = 0
f= file(path,'rb')
Flag = True
#####read 1024 bytes and send it to server each time
while Flag:
if send_size + 1024 >file_size:
data = f.read(file_size-send_size)
Flag = False
else:
data = f.read(1024)
send_size+=1024
sk.send(data)
f.close()
sk.close()
The TCP is a stream of data. That is the problem. TCP do not need to keep message boundaries. So when a client calls something like
connection.send("0123456789")
connection.send("ABCDEFGHIJ")
then a naive server like
while True;
data = conn.recv(1024)
print data + "_"
may print any of:
0123456789_ABCDEFGHIJ_
0123456789ABCDEFGHIJ_
0_1_2_3_4_5_6_7_8_9_A_B_C_D_E_F_G_H_I_J_
The server has no chance to recognize how many sends client called because the TCP stack at client side just inserted data to a stream and the server must be able to process the data received in different number of buffers than the client used.
Your server must contain a logic to separate the header and the data. All of application protocols based on TCP use a mechanism to identify application level boundaries. For example HTTP separates headers and body by an empty line and it informs about the body length in a separate header.
Your program works correctly when server receives a header with the command, name and size in a separate buffer it it fails when client is fast enough and push the data into stream quickly and the server reads header and data in one chunk.
I am working with an asyncio.Protocol server where the purpose is for the client to call the server, but wait until the server has responded and data is returned before stopping the client loop.
Based on the asyncio doc Echo Client and Server here: https://docs.python.org/3/library/asyncio-protocol.html#protocol-example-tcp-echo-server-and-client , results of transport.write(...) are returned immediately when called.
Through experience, calling loop.run_until_complete(coroutine) fails with RuntimeError: Event loop is running.
Running asyncio.sleep(n) in the data_received() method of the server doesn't have any effect either.
yield from asyncio.sleep(n) and yield from asyncio.async(asyncio.sleep(n)) in data_received() both hang the server.
My question is, how do I get my client to wait for the server to write a response before giving back control?
I guess to never use transport/protocol pair directly.
asyncio has Streams API for high-level programming.
Client code can look like:
#asyncio.coroutine
def communicate():
reader, writer = yield from asyncio.open_connection(HOST, PORT)
writer.write(b'data')
yield from writer.drain()
answer = yield from reader.read()
# process answer, maybe send new data back to server and wait for answer again
writer.close()
You don't have to change the client code.
echo-client.py
#!/usr/bin/env python3.4
import asyncio
class EchoClient(asyncio.Protocol):
message = 'Client Echo'
def connection_made(self, transport):
transport.write(self.message.encode())
print('data sent: {}'.format(self.message))
def data_received(self, data):
print('data received: {}'.format(data.decode()))
def connection_lost(self, exc):
print('server closed the connection')
asyncio.get_event_loop().stop()
loop = asyncio.get_event_loop()
coro = loop.create_connection(EchoClient, '127.0.0.1', 8888)
loop.run_until_complete(coro)
loop.run_forever()
loop.close()
The trick is to place your code (including self.transport methods) into a coroutine and use the wait_for() method, with the yield from statement in front of the statements that require their values returned, or ones which take a while to complete:
echo-server.py
#!/usr/bin/env python3.4
import asyncio
class EchoServer(asyncio.Protocol):
def connection_made(self, transport):
peername = transport.get_extra_info('peername')
print('connection from {}'.format(peername))
self.transport = transport
def data_received(self, data):
print('data received: {}'.format(data.decode()))
fut = asyncio.async(self.sleeper())
result = asyncio.wait_for(fut, 60)
#asyncio.coroutine
def sleeper(self):
yield from asyncio.sleep(2)
self.transport.write("Hello World".encode())
self.transport.close()
loop = asyncio.get_event_loop()
coro = loop.create_server(EchoServer, '127.0.0.1', 8888)
server = loop.run_until_complete(coro)
print('serving on {}'.format(server.sockets[0].getsockname()))
try:
loop.run_forever()
except KeyboardInterrupt:
print("exit")
finally:
server.close()
loop.close()
Call echo-server.py and then echo-client.py, the client will wait 2 seconds as determined by asyncio.sleep, then stop.