From: "Daniel P. Zepeda" <daniel@...>
Date: 2002-01-11T17:06:04+09:00
Subject: Re: Something ODD with UDPSocket - Five second wait?

Hello,

On Fri, 11 Jan 2002 07:13:11 +0900
"Ralph Mason" <ralph.mason@telogis.com> wrote:

> Here is an odd thing, so odd that I am sure it must be something I am doing
> wrong.
> 
> I am using UDP to debug a remote application.  So I think, couple of lines
> of ruby and I have my tracer. But I run into a problem, it takes about 5
> seconds from when I send the data (from C) for it to be printed by ruby.
> This does not happen if I send it from ruby - how odd.

I don't know enough about Ruby's UDPSocket internals, but "I get an X second wait"
man times flags a DNS lookup timeout or similar situation. Does UDPSocket try to
reverse-map addresses or something?


> 
> ----------------------------------------
> 
> require "socket"
> 
> sock = UDPSocket.open
> sock.bind("",2600)
> 
> while true
>   p sock.recvfrom(512)
> end
> 
> ----------------------------------------
> 
> So far so good, all works fine.
> 
> I test it with some more ruby, and the data is printed instantly
> 
> ----------------------------------------
> 
> require "socket"
> 
> UDPSocket.open.send("Test debug",0,'localhost',2600)
> 
> ----------------------------------------
> 
> Works fine.    So I start sending to it from C, and it takes 5 seconds for
> the data to appear!!
> 
> I cant figure this out.  Here is the C I am using to send to the ruby
> tracer.
> 
> ----------------------------------------
> int main(int argc, char* argv[])
> {
>  WSADATA wsaData;
>  WSAStartup( MAKEWORD( 1,1 ), &wsaData );
> 
>  const char*  buff="Testing 1..2..3";
> 
>  SOCKET s=socket(AF_INET,SOCK_DGRAM,0);
> 
>  sockaddr_in addr;
>  memset(&addr,0,sizeof(addr));
> 
>  addr.sin_family = AF_INET;
>  addr.sin_port=htons(2600);
>  addr.sin_addr.S_un.S_addr=inet_addr("192.168.1.1");
> 
>  sendto(s,(char*)buff,strlen(buff),0,(sockaddr *)&addr,sizeof(addr));
> 
>  return 0;
> }
> ----------------------------------------
> 
> So I think, perhaps it's somethign to do with my machine. and write the a C
> tracer program.  This one works as I expected the ruby app to work. (and
> also goes to show why I wanted to write it in ruby :-)
> 
> ----------------------------------------
> 
> int main(int argc, char* argv[])
> {
>  WSADATA wsaData;
>  WSAStartup( MAKEWORD( 1,1 ), &wsaData );
> 
>  SOCKET s=socket(AF_INET,SOCK_DGRAM,0);
> 
>  sockaddr_in addr;
>  memset(&addr,0,sizeof(addr));
> 
>  addr.sin_family = AF_INET;
>  addr.sin_port=htons(2600);
>  addr.sin_addr.S_un.S_addr=INADDR_ANY;
> 
>  if ( bind(s,(sockaddr*)&addr,sizeof(addr)) == 0 )
>   while(1)
>   {
>    char buff[512];  ;
> 
>    int i= recvfrom(s,buff,512,0,NULL,NULL);
> 
>    if ( i == SOCKET_ERROR  )
>    {
>     printf("Error in recvfrom %d\n",WSAGetLastError());
>     break;
>    }
> 
>    buff[i]=0;
>    printf("%s\n",buff);
>   }
>   else
>    puts("Failed to bind");
> 
>  return 0;
> }
> ----------------------------------------
> 
> Can anyone help with this?  Has anyone seen this problem before?
> 
> 
> Thanks
> Ralph
> 
> 
> 


-- 
Daniel P. Zepeda
daniel@zepeda-zone.net