Source Code 1992 March/Source_Code_CD-ROM_Walnut_Creek_March_1992.iso/usenet/altsrcs/3/3543/npipeclient.c

C/C++ Source or Header | 1991-06-26 | 5.1 KB | 209 lines

/* Public domain. */

#include <stdio.h>
#include <sys/types.h>
#include <sys/file.h>
#include <signal.h>
#include <fcntl.h>
#include "dupdup.h"
#include "malloc.h"
#include "errno.h"
#include "username.h"
#include "env.h"
#include "getopt.h"
#include "numfiles.h"

#ifndef F_LOCK
#define F_LOCK 1
#endif
#ifndef O_RDONLY
#define O_RDONLY 0
#endif
#ifndef O_WRONLY
#define O_WRONLY 1
#endif
#ifndef O_RDWR
#define O_RDWR 2
#endif

static int flagverbose = 1;

static char errbuf[500];
void die(n,s) int n; char *s;
{ if (flagverbose) fprintf(stderr,"npipeclient: fatal: %s\n",s); exit(n); }
void dies(n,s,t) int n; char *s; char *t;
{ if (flagverbose) fprintf(stderr,"npipeclient: fatal: %s%s\n",s,t); exit(n); }
void diep(n,s) int n; char *s;
{ if (flagverbose) sprintf(errbuf,"npipeclient: fatal: %s",s); perror(errbuf); exit(n); }
void warnp(s) char *s;
{ if (flagverbose) sprintf(errbuf,"npipeclient: warning: %s",s); perror(errbuf); }
void warnsp(s,t) char *s; char *t;
{ if (flagverbose) sprintf(errbuf,"npipeclient: warning: %s%s",s,t); perror(errbuf); }

main(argc,argv,envp)
int argc;
char *argv[];
char *envp[];
{
 int *d;
 int numfiles;
 int arguid;
 int uid;
 int i;
 static char npipelocal[200];
 static char npiperemote[300];
 int fdserv;
 int fdlock;
 int fds2c;
 int fdc2s;
 char fnlock[200];
 char fns2c[200];
 char fnc2s[200];
 char fnserv[200];
 int m;
 int n;
 int r;
 char buf[100];
 char *uname;
 int pid;
 int opt;

 pid = getpid();

 while ((opt = getopt(argc,argv,"qQ")) != EOF)
   switch(opt)
    {
     case 'q':
       flagverbose = 0; break;
     case 'Q':
       flagverbose = 1; break;
     case '?':
       break; /*XXX*/
     default:
       break; /*XXX*/
    }
 argc -= optind; argv += optind;

 if (argc < 3)
   die(1,"need at least three arguments");

 uid = getuid();
 if (username2uid(argv[0],&arguid) == -1)
   dies(2,"cannot figure out username ",argv[0]);
 /* XXX: any permission checks? */

 for (i = 0;argv[0][i];++i)
   if ((argv[0][i] == '/') || (argv[0][i] == ':') || (argv[0][i] == '.') || (argv[0][i] == '\n'))
     dies(4,"illegal characters in username ",argv[0]);

 for (i = 0;argv[1][i];++i)
   if ((argv[1][i] == '/') || (argv[1][i] == '.') || (argv[0][i] == '\n'))
     dies(5,"illegal characters in service ",argv[1]);

 close(6);
 close(7); /* XXX: these have implications that should be documented */

 signal(SIGPIPE,SIG_IGN);

 if (uid2username(uid,&uname) == -1) /* will never happen */
   die(2,"cannot figure out my own username");

 numfiles = NUMFILES;
 d = (int *) malloc(numfiles * sizeof(int));
 if (!d)
   die(6,"cannot malloc");
 for (i = 0;i < numfiles;++i)
   d[i] = -1;

 if (strlen(NPIPEDIR) + strlen(argv[0]) + strlen(argv[1]) + 1 > 90) /*XXX*/
   die(8,"server filenames too long");
 sprintf(fnserv,"%s/%ds%s",NPIPEDIR,arguid,argv[1]);
 sprintf(fnlock,"%s/%dl%s",NPIPEDIR,arguid,argv[1]);
 sprintf(fns2c,"%s/s2c.%d",NPIPEDIR,pid);
 sprintf(fnc2s,"%s/c2s.%d",NPIPEDIR,pid);
 sprintf(buf,"%d",pid);
 n = strlen(buf);
 if (n + strlen(uname) + 10 > sizeof(buf))
   die(8,"username too long");
 strcpy(buf + n + 1,uname);
 n += strlen(uname) + 2;

 if (env_init() == -1)
   die(11,"cannot init environment");
 if (env_put("PROTO=NPIPE") == -1)
   die(11,"out of memory putting PROTO into environment");
 sprintf(npipelocal,"NPIPELOCAL=%s",uname);
 if (env_put(npipelocal) == -1)
   die(11,"out of memory putting NPIPELOCAL into environment");
 sprintf(npiperemote,"NPIPEREMOTE=%s:%s",argv[0],argv[1]);
 if (env_put(npiperemote) == -1)
   die(11,"out of memory putting NPIPEREMOTE into environment");

 /* XXX: fork? not necessary here */

 /* Action! */

 fdlock = open(fnlock,O_RDWR,0);
 if (fdlock == -1)
   diep(1,"cannot open lock file");
 /* Here's the tricky bit: file locking. :-( */
 /* XXX: We assume that anyone with named pipes also has lockf(). */
 if (lockf(fdlock,F_LOCK,1) == -1)
   diep(1,"cannot wait for lock on lock file");

 fdserv = open(fnserv,O_WRONLY,0);
 if (fdserv == -1)
   diep(1,"cannot open server's named pipe");

 if (mknod(fns2c,010600,0) == -1)
   diep(1,"cannot create server-to-client pipe");
 if (mknod(fnc2s,010600,0) == -1)
  {
   unlink(fns2c);
   diep(1,"cannot create client-to-server pipe");
  }

 m = 0;
 r = 0;
 while ((m < n) && ((r = write(fdserv,buf + m,n - m)) > 0))
   m += r;
 if (r <= 0)
  {
   unlink(fnc2s);
   unlink(fns2c);
   die(1,"cannot write pid and username to server");
  }
 close(fdserv); /*XXX*/

 fds2c = open(fns2c,O_RDONLY,0); /* blocks */
 unlink(fns2c);
 if (fds2c == -1)
  {
   unlink(fnc2s);
   die(1,"cannot open server-to-client pipe");
  }
 fdc2s = open(fnc2s,O_WRONLY,0); /* blocks */
 unlink(fnc2s);
 if (fdc2s == -1)
   die(1,"cannot open client-to-server pipe");

 if (read(fds2c,buf,1) < 1)
   diep(1,"cannot read from server-to-client pipe");

 close(fdlock);

 /* Now put fds2c into descriptor 6 and fdc2s into descriptor 7. */
 /* XXX: should check that fdc2s and fds2c are small enough */
 d[fds2c] = 6;
 d[fdc2s] = 7;
 if (dupdup(d,numfiles) == -1)
   diep(10,"cannot dup connection to server");

 if (setreuid(uid,uid) == -1)
   diep(1,"cannot setreuid"); /* will never happen */
 signal(SIGPIPE,SIG_DFL);
 execvp(argv[2],argv + 2);
 warnsp("cannot exec ",argv[2]);
 exit(1);
}