I am fairly new to programming in general and I am using EventMachine on both the client and server side to open a websocket connection between them.
My issue is with the Client side, and when the connection is lost due to network connectivity issues.
def websocket_connection
EM.run do
begin
puts "Connecting"
ws = WebSocket::EventMachine::Client.connect(:uri => "Server Info")
puts "Success WS: #{ws}"
rescue
puts "I've been rescued"
puts "Rescue WS: #{ws}"
ws = nil
sleep 10
websocket_connection
end
ws.onopen do
puts "Connected!"
end
ws.onping do
put "Ping!"
end
ws.onmessage do |msg|
puts msg
end
ws.onclose do |code|
puts "Connection Closed!"
puts "Code: #{code}"
ws = nil
sleep 10
websocket_connection
end
end
end
This connects to the server just fine, but if I pull the network connection and plug it back in I am stuck in an infinite loop of it trying to reconnect with code 1002 (WebSocket protocol error.).
I have tried to call EM.reconnect(server, port, ws) on close, but it crashes and throws this error `connect_server': unable to resolve address: The requested name is valid, but no data of the requested type was found. Which makes sense because it can't contact DNS. Even if wrap the EM.reconnect in a begin rescue it just tries once and never tries again.
I have tried stopping EventMachine and close (EM.stop) but that gets stuck in an infinite loop trying to reconnect.
I am not really sure how to get this client to reconnect to the server after a network lose.
EDIT:
Updated the code above a little bit.
CMD Line:
Success WS: #WebSocket::EventMachine::Client:0x00000002909ac8
Pulled Ethernet Cable
Rescue WS:
Connected Ethernet Cable
Success WS: #WebSocket::EventMachine::Client:0x000000031c42a8
Success WS: #WebSocket::EventMachine::Client:0x000000031a3d50
Success WS: #WebSocket::EventMachine::Client:0x00000003198a90
CTRL + C
block in websocket_connection': undefined methodonopen' for nil:NilClass (NoMethodError)
So it looks like it thinks its connecting, I don't see any connections on the server side.
Well, I couldn't find a way to do a proper reconnect using EventMachine. It looks like weird things happen in EventMachine when you drop your network connection. I ended up relaunching the ruby app under a new Process then killing the current script, not the best way to do this but after a week of trying to get the reconnect working through EventMachine I have just given up. This code works below.
def websocket_restart
exec "ruby script"
exit 0
end
def websocket_connection
EM.run do
begin
puts "Connecting"
ws = WebSocket::EventMachine::Client.connect(:uri => "Server Info")
rescue
websocket_restart
end
ws.onopen do
puts "Connected!"
end
ws.onping do
put "Ping!"
end
ws.onmessage do |msg|
puts msg
end
ws.onclose do |code|
puts "Connection Closed!"
puts "Code: #{code}"
websocket_restart
end
end
end
Related
Intro
I have a client that makes numerous SSL connections to a 3rd party service. In certain cases, the 3rd party stops responding during the socket and ssl negotiation process. When this occurs, my current implementation "sits" for hours on end before timing out.
To combat this, I'm trying to implement the following process:
require 'socket'
require 'openssl'
# variables
host = '....'
port = ...
p12 = #OpenSSL::PKCS12 object
# set up socket
addr = Socket.getaddrinfo(host, nil)
sockaddr = Socket.pack_sockaddr_in(port, addr[0][3])
socket = Socket.new(Socket.const_get(addr[0][0]), Socket::SOCK_STREAM, 0)
socket.setsockopt(Socket::IPPROTO_TCP, Socket::TCP_NODELAY, 1)
begin
socket.connect_nonblock(sockaddr)
rescue IO::WaitWritable
if IO.select(nil, [socket], nil, timeout)
begin
socket.connect_nonblock(sockaddr)
rescue Errno::EISCONN
puts "socket connected"
rescue
puts "socket error"
socket.close
raise
end
else
socket.close
raise "Connection timeout"
end
end
# negotiate ssl
context = OpenSSL::SSL::SSLContext.new
context.cert = p12.certificate
context.key = p12.key
ssl_socket = OpenSSL::SSL::SSLSocket.new(socket, context)
ssl_socket.sync_close = true
puts "ssl connecting"
ssl_socket.connect_nonblock
puts "ssl connected"
# cleanup
ssl_socket.close
puts "socket closed"
ssl_socket.connect_nonblock will eventually be wrapped in a similar structure as socket.connect_nonblock is.
The Problem
The issue I'm running into is that ssl_socket.connect_nonblock raises the following when run:
`connect_nonblock': read would block (OpenSSL::SSL::SSLError)
Instead, I'd expect it to raise an IO::WaitWritable as socket.connect_nonblock does.
I've scoured the internet for information on this particular error but can't find anything of particular use. From what I gather, others have had success using this method, so I'm not sure what I'm missing. For the sake of completeness, I've found the same results with both ruby 2.2.0 and 1.9.3.
Any suggestions are greatly appreciated!
Have same problem, I tried below, it seems works right for my situation.
ssl_socket = OpenSSL::SSL::SSLSocket.new socket, context
ssl_socket.sync = true
begin
ssl_socket.connect_nonblock
rescue IO::WaitReadable
if IO.select([ssl_socket], nil, nil, timeout)
retry
else
# timeout
end
rescue IO::WaitWritable
if IO.select(nil, [ssl_socket], nil, timeout)
retry
else
# timeout
end
end
I am attempting to create a better port scanner by implementing more error handling, and I've run into a bit of trouble.
def pscan(host_name, port)
begin
sock = Socket.new(:INET, :STREAM)
raw = Socket.sockaddr_in(port, host_name)
if sock.connect(raw)
puts "Port #{port} is up!"
rescue (Errno::ECONNREFUSED)
false
rescue (Errno::ETIMEDOUT)
puts "Port #{port} timed out!"
end
end
def run
port = 1
begin
while port <= ARGV[1].to_i do
popen(ARGV[0], port)
port += 1
end
rescue (Errno::EHOSTUNREACH)
puts "No path to host"
rescue(Interrupt)
puts " Process interrupted"
end
end
run
The trouble is that for each port scanned, it will print "No path to host", instead of printing that once and then closing the socket. I'm clearly doing it wrong but everywhere online I find simple code closes a socket connection this way.
I think that you forgot to close the if statement. Also, use 'ensure' to close it.
Try this:
def pscan(host_name, port)
begin
sock = Socket.new(:INET, :STREAM)
raw = Socket.sockaddr_in(port, host_name)
if sock.connect(raw)
puts "Port #{port} is up!"
end
rescue (Errno::ECONNREFUSED)
false
rescue (Errno::ETIMEDOUT)
puts "Port #{port} timed out!"
rescue (Errno::EHOSTUNREACH)
puts "No path to host"
ensure
sock.close
end
end
Like you mentioned in your comments and your code changes, you would have to move the socket closing into the block that's calling your code rather than inside of that code itself, since the block of code will continuously call the method and the socket will never actually be closed.
You'll basically have to do what you posted in your code:
require 'socket'
def pscan(host_name, port)
begin
sock = Socket.new(:INET, :STREAM)
raw = Socket.sockaddr_in(port, host_name)
if sock.connect(raw)
puts "Port #{port} is up!"
end
rescue (Errno::ECONNREFUSED)
puts "Connection refused to port #{port}"
false
rescue (Errno::ETIMEDOUT)
puts "Port #{port} timed out!"
false
end
end
def run
puts "Attempting to scan host #{ARGV[0]}"
port = 1
begin
while port <= ARGV[1].to_i do
pscan(ARGV[0], port)
port += 1
end
rescue (Errno::EHOSTUNREACH)
puts "No path to host #{ARVG[0]}"
rescue(Interrupt)
puts "Process interrupted"
end
end
run
Some thoughts: you may not always get "No path to host" errors when running your code; when I tested it in my network, I never got a "No path to host" error but always got a "Port ... timed out!" error even when I tested it against known unreachable hosts such as 10.0.0.1. You'll have to be wary of that when you run your code in other networks as you might get different results.
I'm writing a ruby program that has 2 threads. One that listens on an incoming UDP connection and another that broadcasts on a websocket from which browsers on the client side read.I'm using the em-websocket gem. However, My UDP listener thread never gets called and it looks like the code stays within the websocket initialization code. I'm guessing because em-websocket is blocking, but I haven't been able to find any info online that suggests that. Is it an error on my side? I'm kinda new to ruby so I'm not able to figure out what I'm doing wrong.
require 'json'
require 'em-websocket'
require 'socket'
socket=nil
text="default"
$x=0
EventMachine.run do
EventMachine::WebSocket.start(:host => "0.0.0.0", :port => 8080) do |ws|
ws.onopen {
ws.send "Hello Client!"
socket=ws
$x=1
}
ws.onmessage { |msg| socket.send "Pong: #{msg}" }
ws.onclose { puts "WebSocket closed" }
end
end
def listen()
puts "listening..."
s = UDPSocket.new
s.bind(nil, 3000)
while 1<2 do
text, sender = s.recvfrom(1024)
puts text
if $x==1 then
socket.send text
end
end
end
t2=Thread.new{listen()}
t2.join
em-websocket is non-blocking, however UDPSocket#recv_from is. Might be better to just use EventMachine's open_datagram_socket instead.
Another thing to note: you should not expose socket as a "global" variable. Every time somebody connects the reference to the previously connected client will be lost. Maybe make some sort of repository for socket connections, or use an observer pattern to broadcast messages when something comes in. What I would do is have a dummy object act as an observer, and whenever a socket is connected/disconnect you register/unregister from the observer:
require 'observer'
class Dummy
include Observable
def receive_data data
changed true
notify_observers data
end
end
# ... later on ...
$broadcaster = Dummy.new
class UDPHandler < EventMachine::Connection
def receive_data data
$broadcaster.receive_data data
end
end
EventMachine.run do
EM.open_datagram_socket "0.0.0.0", 3000, UDPHandler
EM::WebSocket.start :host => "0.0.0.0", :port => 8080 do |ws|
ws.onopen do
$broadcaster.add_observer ws
end
ws.onclose do
$broadcaster.delete_observer ws
end
# ...
end
end
The whole point of EventMachine is to abstract away from the basic socket and threading structure, and handle all the asynchronous bits internally. It's best not to mix the classical libraries like UDPSocket or Thread with EventMachine stuff.
I wrote a TCP server using below code. This is to receive GPS location data via GSM network from a remote GPS sensor.
require 'socket'
server = TCPServer.open(2000) # Listen on port 2000
sockets = [server] # An array of sockets we'll monitor
log = STDOUT # Send log messages to standard out
while true
ready = select(sockets)
readable = ready[0]
readable.each do |socket|
if socket == server
client = server.accept
sockets << client
log.puts "Accepted connection from #{client.peeraddr[2]}"
while msg = client.gets
puts msg
end
else
input = socket.gets
if !input
log.puts "Client on #{socket.peeraddr[2]} disconnected"
sockets.delete(socket)
socket.close
next
end
input.chop!
if (input == "quit")
socket.puts("Bye");
log.puts "Closing connnection to #{socket.peeraddr[2]}"
sockets.delete(socket)
socket.close
else
socket.puts(input.reverse)
end
end
end
end
and then I wrote one using Eventmachine. Code as below:
require 'eventmachine'
module EchoServer
def post_init
puts "-- someone connected to the echo server!"
end
def receive_data data
puts data
end
def unbind
puts "-- someone disconnected from the echo server!"
end
end
EventMachine::run {
EventMachine::start_server "127.0.0.1", 2000, EchoServer
}
However, this eventmachine code will not receive nor display the data. Any part of the Eventmachine code that is wrong?
Thanks
I think your problem is that you are listening on localhost only, try this:
EM::run do
EM.start_server "0.0.0.0", 2000, EchoServer
end
I'm trying to build a websocket server where each client establish its own redis connections used for publish and subscribe.
When the redis server is running I can see the two new connections being established when a client connects to the websocket server and I can also publish data to the client, but when the client drops the connection to the websocket server I also want to disconnect from Redis . How can I do this?
Maybe I'm doing it wrong, but this is my code.
#require 'redis'
require 'em-websocket'
require 'em-hiredis'
require 'json'
CLIENTS = Hash.new
class PubSub
def initialize(client)
#socket = client.ws
# These clients can only be used for pub sub commands
#publisher = EM::Hiredis.connect #Later I will like to disconnect this
#subscriber = EM::Hiredis.connect #Later I will like to disconnect this
client.connections << #publisher << #subscriber
end
def subscribe(channel)
#channel = channel
#subscriber.subscribe(channel)
#subscriber.on(:message) { |chan, message|
#socket.send message
}
end
def publish(channel,msg)
#publisher.publish(channel, msg).errback { |e|
puts [:publisherror, e]
}
end
def unsubscribe()
#subscriber.unsubscribe(#channel)
end
end
class Client
attr_accessor :connections, :ws
def initialize(ws)
#connections = []
#ws = ws
end
end
EventMachine.run do
# Creates a websocket listener
EventMachine::WebSocket.start(:host => '0.0.0.0', :port => 8081) do |ws|
ws.onopen do
# I instantiated above
puts 'CLient connected. Creating socket'
#client = Client.new(ws)
CLIENTS[ws] = #client
end
ws.onclose do
# Upon the close of the connection I remove it from my list of running sockets
puts 'Client disconnected. Closing socket'
#client.connections.each do |con|
#do something to disconnect from redis
end
CLIENTS.delete ws
end
ws.onmessage { |msg|
puts "Received message: #{msg}"
result = JSON.parse(msg)
if result.has_key? 'channel'
ps = PubSub.new(#client)
ps.subscribe(result['channel'])
elsif result.has_key? 'publish'
ps = PubSub.new(ws)
ps.publish(result['publish']['channel'],result['publish']['msg']);
end
}
end
end
This version of em-hiredis supports close connection: https://github.com/whatupdave/em-hiredis
Here is how I would (and did many times) this:
instead of always opening and closing connections for each client you can keep 1 connection open per Thread/Fiber dependeing on what you are basing your concurrency on, that way if you are using a poll of Thread/Fibers once each one of them have its connections they will keep it and reuse them.
I did not worked much with websocket until now (I was waiting for a standard implementation) but I am sure you can apply that thinking to it too.
You can also do what rails/activerecord: keeo a pool of redis connection, each time you need to use a connection you request one, use it and realease it, it could look like this:
def handle_request(request)
#redis_pool.get_connection do |c|
# [...]
end
end
before yielding the block a connection is taken from the available ones and after it the connection is marked as free.
This was added to em-hiredis: https://github.com/mloughran/em-hiredis/pull/6