usr.bin/rdist/rshrcmd.c

   1
   2 /*
   3  * This is an rcmd() replacement originally by
   4  * Chris Siebenmann <cks@utcc.utoronto.ca>.
   5  *
   6  * $FreeBSD: src/usr.bin/rdist/rshrcmd.c,v 1.6 1999/08/28 01:05:08 peter Exp $
   7  */
   8
   9 #include <sys/types.h>
  10 #include <sys/socket.h>
  11 #include <sys/wait.h>
  12
  13 #include <netdb.h>
  14 #include <signal.h>
  15
  16 #include "defs.h"
  17
  18 #if     !defined(DIRECT_RCMD)
  19
  20 static char *
  21 xbasename(char *s)
  22 {
  23         char *ret;
  24
  25         ret = strrchr(s, '/');
  26         if (ret && ret[1])
  27                 return (ret + 1);
  28         return s;
  29 }
  30
  31
  32 /*
  33  * This is a replacement rcmd() function that uses the rsh(1c)
  34  * program in place of a direct rcmd() function call so as to
  35  * avoid having to be root.
  36  */
  37 int
  38 rshrcmd(char **ahost, u_short port, char *luser, char *ruser, char *cmd, int *fd2p)
  39 {
  40         int             cpid, sp[2];
  41         struct hostent  *hp;
  42
  43         /* insure that we are indeed being used as we thought. */
  44         if (fd2p != NULL)
  45                 return -1;
  46         /* validate remote hostname. */
  47         hp = gethostbyname(*ahost);
  48         if (hp == NULL) {
  49                 error("%s: unknown host", *ahost);
  50                 return -1;
  51         }
  52
  53         /* get a socketpair we'll use for stdin and stdout. */
  54         if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) < 0) {
  55                 error("socketpair(AF_UNIX, SOCK_STREAM, 0) failed: %s.",
  56                       strerror(errno));
  57                 return -1;
  58         }
  59
  60         cpid = fork();
  61         if (cpid < 0) {
  62                 error("fork failed: %s.", strerror(errno));
  63                 return -1;      /* error. */
  64         }
  65         if (cpid == 0) {
  66                 /* child. we use sp[1] to be stdin/stdout, and close
  67                    sp[0]. */
  68                 close(sp[0]);
  69                 if (dup2(sp[1], 0) < 0 || dup2(0,1) < 0) {
  70                         error("dup2 failed: %s.", strerror(errno));
  71                         _exit(255);
  72                 }
  73                 /* fork again to lose parent. */
  74                 cpid = fork();
  75                 if (cpid < 0) {
  76                         error("fork to lose parent failed: %s.", strerror(errno));
  77                         _exit(255);
  78                 }
  79                 if (cpid > 0)
  80                         _exit(0);
  81                 /* in grandchild here. */
  82
  83                 /*
  84                  * If we are rdist'ing to "localhost" as the same user
  85                  * as we are, then avoid running remote shell for efficiency.
  86                  */
  87                 if (strcmp(*ahost, "localhost") == 0 &&
  88                     strcmp(luser, ruser) == 0) {
  89                         execlp(_PATH_BSHELL, xbasename(_PATH_BSHELL), "-c",
  90                                cmd, NULL);
  91                         error("execlp %s failed: %s.", _PATH_BSHELL, strerror(errno));
  92                 } else {
  93                         execlp(path_rsh, xbasename(path_rsh),
  94                                *ahost, "-l", ruser, cmd, NULL);
  95                         error("execlp %s failed: %s.", path_rsh,
  96                                 strerror(errno));
  97                 }
  98                 _exit(255);
  99         }
 100         if (cpid > 0) {
 101                 /* parent. close sp[1], return sp[0]. */
 102                 close(sp[1]);
 103                 /* reap child. */
 104                 wait(0);
 105                 return sp[0];
 106         }
 107         /*NOTREACHED*/
 108         return (-1);
 109 }
 110
 111 #endif  /* !DIRECT_RCMD */