Subversion Repositories planix.SVN

#include <stdlib.h>
#include <sys/types.h>
#include <unistd.h>
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <libnet.h>

#define NAMELEN 28

static int      nettrans(char*, char*, int na, char*, int);

/*
 *  announce a network service.
 */
int
announce(char *addr, char *dir)
{
        int ctl, n, m;
        char buf[3*NAMELEN];
        char buf2[3*NAMELEN];
        char netdir[2*NAMELEN];
        char naddr[3*NAMELEN];
        char *cp;

        /*
         *  translate the address
         */
        if(nettrans(addr, naddr, sizeof(naddr), netdir, sizeof(netdir)) < 0)
                return -1;

        /*
         * get a control channel
         */
        ctl = open(netdir, O_RDWR);
        if(ctl<0)
                return -1;
        cp = strrchr(netdir, '/');
        *cp = 0;

        /*
         *  find out which line we have
         */
        n = sprintf(buf, "%.*s/", 2*NAMELEN+1, netdir);
        m = read(ctl, &buf[n], sizeof(buf)-n-1);
        if(n<=0){
                close(ctl);
                return -1;
        }
        buf[n+m] = 0;

        /*
         *  make the call
         */
        n = sprintf(buf2, "announce %.*s", 2*NAMELEN, naddr);
        if(write(ctl, buf2, n)!=n){
                close(ctl);
                return -1;
        }

        /*
         *  return directory etc.
         */
        if(dir)
                strcpy(dir, buf);
        return ctl;
}

/*
 *  listen for an incoming call
 */
int
listen(char *dir, char *newdir)
{
        int ctl, n, m;
        char buf[3*NAMELEN];
        char *cp;

        /*
         *  open listen, wait for a call
         */
        sprintf(buf, "%.*s/listen", 2*NAMELEN+1, dir);
        ctl = open(buf, O_RDWR);
        if(ctl < 0)
                return -1;

        /*
         *  find out which line we have
         */
        strcpy(buf, dir);
        cp = strrchr(buf, '/');
        *++cp = 0;
        n = cp-buf;
        m = read(ctl, cp, sizeof(buf) - n - 1);
        if(n<=0){
                close(ctl);
                return -1;
        }
        buf[n+m] = 0;

        /*
         *  return directory etc.
         */
        if(newdir)
                strcpy(newdir, buf);
        return ctl;

}

/*
 *  accept a call, return an fd to the open data file
 */
int
accept(int ctl, char *dir)
{
        char buf[128];
        char *num;
        long n;

        num = strrchr(dir, '/');
        if(num == 0)
                num = dir;
        else
                num++;

        sprintf(buf, "accept %s", num);
        n = strlen(buf);
        write(ctl, buf, n); /* ignore return value, netowrk might not need accepts */

        sprintf(buf, "%s/data", dir);
        return open(buf, O_RDWR);
}

/*
 *  reject a call, tell device the reason for the rejection
 */
int
reject(int ctl, char *dir, char *cause)
{
        char buf[128];
        char *num;
        long n;

        num = strrchr(dir, '/');
        if(num == 0)
                num = dir;
        else
                num++;
        sprintf(buf, "reject %s %s", num, cause);
        n = strlen(buf);
        if(write(ctl, buf, n) != n)
                return -1;
        return 0;
}

/*
 *  perform the identity translation (in case we can't reach cs)
 */
static int
identtrans(char *addr, char *naddr, int na, char *file, int nf)
{
        char reply[4*NAMELEN];
        char *p;

        USED(nf);

        /* parse the network */
        strncpy(reply, addr, sizeof(reply));
        reply[sizeof(reply)-1] = 0;
        p = strchr(addr, '!');
        if(p)
                *p++ = 0;

        sprintf(file, "/net/%.*s/clone", na - sizeof("/net//clone"), reply);
        strncpy(naddr, p, na);
        naddr[na-1] = 0;

        return 1;
}

/*
 *  call up the connection server and get a translation
 */
static int
nettrans(char *addr, char *naddr, int na, char *file, int nf)
{
        int fd;
        char reply[4*NAMELEN];
        char *cp;
        long n;

        /*
         *  ask the connection server
         */
        fd = open("/net/cs", O_RDWR);
        if(fd < 0)
                return identtrans(addr, naddr, na, file, nf);
        if(write(fd, addr, strlen(addr)) < 0){
                close(fd);
                return -1;
        }
        lseek(fd, 0, 0);
        n = read(fd, reply, sizeof(reply)-1);
        close(fd);
        if(n <= 0)
                return -1;
        reply[n] = 0;

        /*
         *  parse the reply
         */
        cp = strchr(reply, ' ');
        if(cp == 0)
                return -1;
        *cp++ = 0;
        strncpy(naddr, cp, na);
        naddr[na-1] = 0;
        strncpy(file, reply, nf);
        file[nf-1] = 0;
        return 0;
}