topic Socket Client set timeout in Operating System - HP-UX

Socket Client set timeout

Alfonso_15 — Tue, 09 Mar 2004 16:04:24 GMT

Hi friends. I have an application Client in HP10.20. How I can put a timeout(example 5 seconds) in the connect(socket, addr, addrlen) sentence for return after this 5 seconds if can not connect to server during this time. Right now the sentence returns after 75 seconds, and is to late for my application takes other actions.
Thanks a lot for your help.

Re: Socket Client set timeout

Mark Grant — Wed, 10 Mar 2004 04:22:57 GMT

Not sure what language you are using here but generally, you want to set an "alarm" for 5 seconds before you do the "socket". "Perl" has an "alarm" function for this. If you trap "SIGALRM" you then have your timeour.

Re: Socket Client set timeout

Alfonso_15 — Wed, 10 Mar 2004 10:11:26 GMT

Hi. Thanks for the answer. I am using gcc. and the delay is in the sentence connect(socket, struct sock_addr, addrlen); This time out is not a property configurable for the socket? or maybe in the struct sock_addr? Thanks again.

Re: Socket Client set timeout

susan gregory_1 — Thu, 11 Mar 2004 11:51:27 GMT

I would guess that one of the ndd settings may be affecting your program's connect. I don't know of a way to get connect to time out like you can a select(). It sounds like something in your network protocol is set to timeout after 75 seconds (and it could be two or more parms, such as a "retransmission interval" multiplied by a "number of retransmission attempts" before giving up).
You may want to use ndd -get to see your settings and may want to very cautiously modified a few. You may want to call the HP RC for some advice on ndd as setting your timeout to 5 is going to affect more than just your program.

Re: Socket Client set timeout

Ken_109 — Thu, 18 Mar 2004 16:51:09 GMT

Alfonso,Here is my solution: TEST and RETEST at your own risk... :)#include /* global */static jmp_buf env;void alarm_handler (int sig){ longjmp (env, 1);}... In your subroutine setup socket stuff..varsetc... /* Set up signal handler */ signal (SIGALRM, alarm_handler) /* open up a connection to the local server port */ if (setjmp (env) == 0) { alarm (20); /* 20 Second timeout */ if ((clnt = connect(socket, addr, addrlen) <0) { alarm (0); fprintf (stderr, "Could not open socket on Host (%s) on port(%s) \n", skthost, port); return FAILURE; } alarm (0); } else { fprintf (stderr, "Timeout opening socket on Host (%s) on port(%s)\n", skthost, port); return FAILURE; }Now for what is going on here... The signal handler "alarm_handler" returns a 1 to the setjum(env) call. Setjmp saves the stack context, it returns 0 when returned directly and a 1 when returned from longjmp.If the alarm is triggered (ie alarm(20) after 20 seconds... then the signal handler is executed and longjmp is called. The context is reset and a 1 is returned dropping you into the else section.Good luck... Ken