writing xinetd service

[bentaylor]

Hello, any network programming gurus out there?

I am trying to make a service to receive a url over the network (then download the torrent file, and load it into my torrent program, but basics first....) Since I read up on the net that if I configure it as an xinetd service, then it can just use stdin and stdout for communicating over the socket.

I did this, however I am having trouble getting it to work.

The code thus far is as such:

#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>



int main(int argc, char *argv[])
{
        FILE* logfile = fopen("/home/torrent/loadfile.log", "w");
        fputs("starting\n", logfile);
        char* url = NULL;
        size_t linesize = 0;
        ssize_t urllen = getline(&url, &linesize, stdin);
        fputs("got url\n", logfile);
        if(urllen <= 0) {printf("no file specified\n");return 1;}
        printf("thanks!");
        return 0;
}

i.e. I am using getline to read data from stdin - this should read data from the socket, right?
Basically this is a "client sends data first" type affair.

HOWEVER - it doesn't appear to even be completing the second line - i.e. when I look at /home/torrent/loadfile.log it has been created (so therefore the call to fopen must have worked) - however it is empty, zero bytes - so therefore even the first fputs didn't work.
I thought it would be a permissions issue, but I have got the service running as root, as can be seen from my configuration in /etc/xinetd.d/loadfile:

service loadfile
{
        disable         = no
        id              = loadfile
#       type            = INTERNAL
        wait            = no
        socket_type     = stream
        user            = root
        group           = root
        server          = /usr/sbin/loadfile
        server_args     =
        port            = 12345
}

I commented out the 'internal' line as it didn't work with that - xinetd puts some message about it not recognizing the service into syslog if I have the internal flag on. I also find it only works to list it in /etc/services.

Any idea what could be the problem?

I don't understand why it's opening the log file but isn't even getting as far as writing to it - so I am stumped as to how to debug this now.

any help much appreciated.

[sharnois]

fopen uses buffered IO and you are not calling fclose. Using setvbuf with a type of _IOLBF sould send each line into the file...