# Socket send functions only allow you to send strings? **URL:** \ **Category:** ruby-talk\ **Created:** [4 September 2007 22:53 UTC](https://rubytalk.org/t/socket-send-functions-only-allow-you-to-send-strings/40389 "2007-09-04T22:53:10Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![Ryan\_Parmeter](https://avatars.discourse-cdn.com/v4/letter/r/b19c9b/32.png) [@Ryan\_Parmeter](https://rubytalk.org/u/Ryan_Parmeter)\ **Post date:** [4 September 2007 22:53 UTC](https://rubytalk.org/t/socket-send-functions-only-allow-you-to-send-strings/40389/1 "2007-09-04T22:53:10Z")
I am writing a small TimeP (RFC 868) server to sync time with some networking equipment. The equipment that shall go nameless requires the use of UDP. As far as I can tell, my only option to write to a UDPSocket is to use the send method, which takes a string. I need to send a 32bit integer representing the date in a UDP packet and I'd love to use something like: myUDPsocket.send( Time.now.to\_i, 0, host, port) In my situation I can't change the receiving program to accept a string or I could do it that way. I can't convert the integer to a string either because that would blow my 32 bit requirement. Does anyone have any idea? ~Parkingmeter > **···** > > -- > Posted via [http://www.ruby-forum.com/](http://www.ruby-forum.com/). ---
**Author:** ![Patrick\_Hurley1](https://avatars.discourse-cdn.com/v4/letter/p/b77776/32.png) [@Patrick\_Hurley1](https://rubytalk.org/u/Patrick_Hurley1)\ **Post date:** [4 September 2007 22:59 UTC](https://rubytalk.org/t/socket-send-functions-only-allow-you-to-send-strings/40389/2 "2007-09-04T22:59:44Z")
Try ri Array#pack [number].pack('i') should do the trick. pth > **···** > > On 9/4/07, Ryan Parmeter \ wrote: > > > I am writing a small TimeP (RFC 868) server to sync time with some > > networking equipment. The equipment that shall go nameless requires the > > use of UDP. > > > > As far as I can tell, my only option to write to a UDPSocket is to use > > the send method, which takes a string. I need to send a 32bit integer > > representing the date in a UDP packet and I'd love to use something > > like: > > > > myUDPsocket.send( Time.now.to\_i, 0, host, port) > > > > In my situation I can't change the receiving program to accept a string > > or I could do it that way. I can't convert the integer to a string > > either because that would blow my 32 bit requirement. Does anyone have > > any idea? > > > > ~Parkingmeter > > -- > > Posted via [http://www.ruby-forum.com/\](http://www.ruby-forum.com/%5C). ---
**Author:** ![Joel\_VanderWerf1](https://avatars.discourse-cdn.com/v4/letter/j/94ad74/32.png) [@Joel\_VanderWerf1](https://rubytalk.org/u/Joel_VanderWerf1)\ **Post date:** [4 September 2007 23:05 UTC](https://rubytalk.org/t/socket-send-functions-only-allow-you-to-send-strings/40389/3 "2007-09-04T23:05:41Z")
Ryan Parmeter wrote: > I am writing a small TimeP (RFC 868) server to sync time with some > networking equipment. The equipment that shall go nameless requires the > use of UDP. > > As far as I can tell, my only option to write to a UDPSocket is to use > the send method, which takes a string. I need to send a 32bit integer > representing the date in a UDP packet and I'd love to use something > like: > > myUDPsocket.send( Time.now.to\_i, 0, host, port) > > In my situation I can't change the receiving program to accept a string > or I could do it that way. I can't convert the integer to a string > either because that would blow my 32 bit requirement. Does anyone have > any idea? Strings are just blobs of binary data, when they go through #send. The receiver doesn't know it started life as a ruby string. If you want structure, use #pack. You'll need to know what byte-order the client and server should use to communicate. Assuming big-endian: myUDPsocket.send([Time.now.to\_i].pack("N"), 0, host, port) > **···** > > -- >        vjoel : Joel VanderWerf : path berkeley edu : 510 665 3407 ---
**Author:** ![Kirk\_Haines](https://avatars.discourse-cdn.com/v4/letter/k/c6cbf5/32.png) [@Kirk\_Haines](https://rubytalk.org/u/Kirk_Haines)\ **Post date:** [4 September 2007 23:07 UTC](https://rubytalk.org/t/socket-send-functions-only-allow-you-to-send-strings/40389/4 "2007-09-04T23:07:37Z")
A string is just a sequence of bytes. It can be anything. In your case, you need to encode a decimal number as returned by Time.now.to\_i into 32 bits. myUDPsocket.send( [Time.now.to\_i].pack('i') ) That may be what you need. [http://ruby-doc.org/core/classes/Array.html#M002245](http://ruby-doc.org/core/classes/Array.html#M002245) For more information. Kirk Haines > **···** > > On Wed, 5 Sep 2007, Ryan Parmeter wrote: > > > As far as I can tell, my only option to write to a UDPSocket is to use > > the send method, which takes a string. I need to send a 32bit integer > > representing the date in a UDP packet and I'd love to use something > > like: > > > > myUDPsocket.send( Time.now.to\_i, 0, host, port) > > > > In my situation I can't change the receiving program to accept a string > > or I could do it that way. I can't convert the integer to a string > > either because that would blow my 32 bit requirement. Does anyone have > > any idea? ---
**Author:** ![See](https://avatars.discourse-cdn.com/v4/letter/s/c68b51/32.png) [@See](https://rubytalk.org/u/See)\ **Post date:** [5 September 2007 03:40 UTC](https://rubytalk.org/t/socket-send-functions-only-allow-you-to-send-strings/40389/5 "2007-09-05T03:40:54Z")
In article \<63fd7d04f963970925560990c6583e9d@ruby-forum.com\>, Ryan Parmeter \ writes: > I am writing a small TimeP (RFC 868) server to sync time with some > networking equipment. The equipment that shall go nameless requires the > use of UDP. > > As far as I can tell, my only option to write to a UDPSocket is to use > the send method, which takes a string. I need to send a 32bit integer > representing the date in a UDP packet and I'd love to use something > like: > > myUDPsocket.send( Time.now.to\_i, 0, host, port) > > In my situation I can't change the receiving program to accept a string > or I could do it that way. I can't convert the integer to a string > either because that would blow my 32 bit requirement. Does anyone have > any idea? > > ~Parkingmeter Here, I had this script lying about from one of my earlier experiments with Ruby sockets: - dmw ------ start of code ------- #! /usr/bin/env ruby # nettimesvr.rb - implement Time Server for RFC 868 PROGNAME = 'nettimesvr.rb' timeport = Socket.getservbyname('time', 'udp') # port 37 # timeport = 50037 # for testing RFC868\_POSIX\_ADJMENT = 2\_208\_988\_800 # diff between RFC 868 and POSIX POSIX\_EPOCH\_ADJMENT = Time.gm(1970, 'Jan', 1).to\_i require 'socket' def curnettime()         return Time.new.to\_i + (RFC868\_POSIX\_ADJMENT - POSIX\_EPOCH\_ADJMENT) end port = timeport begin         case ARGV.size         when 1: port = Integer(ARGV[0])         when 0: nil         else; abort "Usage: #{PROGNAME} [port]"         end rescue ArgumentError =\> badarg         abort "Argument conversion error: #{badarg}" end puts "Listening on port #{port}\n" UDPSocket.open { |sock|         sock.bind(Socket::INADDR\_ANY, port)         loop do                         # if we try to receive zero bytes, we get an error                 rmthost = sock.recvfrom(1) [1] # no body expected                 puts "Accepted request from #{rmthost [2]}"                 nettime = [curnettime()].pack('N')                 sock.send(nettime, 0, rmthost[2], rmthost[1])         end } ------ end of code ------- > **···** > > -- > . Douglas Wells . Connection Technologies . > . Internet: -sp9804- -at - contek.com- . ---
**Author:** ![Francis\_Cianfrocca](https://avatars.discourse-cdn.com/v4/letter/f/7bcc69/32.png) [@Francis\_Cianfrocca](https://rubytalk.org/u/Francis_Cianfrocca)\ **Post date:** [5 September 2007 00:46 UTC](https://rubytalk.org/t/socket-send-functions-only-allow-you-to-send-strings/40389/6 "2007-09-05T00:46:10Z")
Actually, to support RFC-868, you have to use the same epoch that NTP uses, rather than the Unix epoch. The current time in raw form would be Time.now.to\_i + 0x83aa7e80. Pack into 32 bits (taking care to keep the conversion unsigned), convert to network-order as necessary, write a four-byte UDP datagram, and away you go. > **···** > > On 9/4/07, khaines@enigo.com \ wrote: > > > On Wed, 5 Sep 2007, Ryan Parmeter wrote: > > > > \> As far as I can tell, my only option to write to a UDPSocket is to use > > \> the send method, which takes a string. I need to send a 32bit integer > > \> representing the date in a UDP packet and I'd love to use something > > \> like: > > \> > > \> myUDPsocket.send( Time.now.to\_i, 0, host, port) > > \> > > \> In my situation I can't change the receiving program to accept a string > > \> or I could do it that way. I can't convert the integer to a string > > \> either because that would blow my 32 bit requirement. Does anyone have > > \> any idea? > > > > A string is just a sequence of bytes. It can be anything. > > > > In your case, you need to encode a decimal number as returned by > > Time.now.to\_i into 32 bits. > > > > myUDPsocket.send( [Time.now.to\_i].pack('i') ) > > > > That may be what you need. > > > > [class Array - RDoc Documentation](http://ruby-doc.org/core/classes/Array.html#M002245) > > > > For more information. > > > > Kirk Haines