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  * $DragonFly: src/usr.bin/rdist/rshrcmd.c,v 1.3 2004/07/24 19:45:10 eirikn Exp $
   8  */
   9
  10 #include <sys/types.h>
  11 #include <sys/socket.h>
  12 #include <sys/wait.h>
  13
  14 #include <netdb.h>
  15 #include <signal.h>
  16
  17 #include "defs.h"
  18
  19 #if     !defined(DIRECT_RCMD)
  20
  21 static char *
  22 xbasename(char *s)
  23 {
  24         char *ret;
  25
  26         ret = strrchr(s, '/');
  27         if (ret && ret[1])
  28                 return (ret + 1);
  29         return s;
  30 }
  31
  32
  33 /*
  34  * This is a replacement rcmd() function that uses the rsh(1c)
  35  * program in place of a direct rcmd() function call so as to
  36  * avoid having to be root.
  37  */
  38 int
  39 rshrcmd(char **ahost, u_short port, char *luser, char *ruser, char *cmd, int *fd2p)
  40 {
  41         int             cpid, sp[2];
  42         struct hostent  *hp;
  43
  44         /* insure that we are indeed being used as we thought. */
  45         if (fd2p != 0)
  46                 return -1;
  47         /* validate remote hostname. */
  48         hp = gethostbyname(*ahost);
  49         if (hp == 0) {
  50                 error("%s: unknown host", *ahost);
  51                 return -1;
  52         }
  53
  54         /* get a socketpair we'll use for stdin and stdout. */
  55         if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) < 0) {
  56                 error("socketpair(AF_UNIX, SOCK_STREAM, 0) failed: %s.",
  57                       strerror(errno));
  58                 return -1;
  59         }
  60
  61         cpid = fork();
  62         if (cpid < 0) {
  63                 error("fork failed: %s.", strerror(errno));
  64                 return -1;      /* error. */
  65         }
  66         if (cpid == 0) {
  67                 /* child. we use sp[1] to be stdin/stdout, and close
  68                    sp[0]. */
  69                 close(sp[0]);
  70                 if (dup2(sp[1], 0) < 0 || dup2(0,1) < 0) {
  71                         error("dup2 failed: %s.", strerror(errno));
  72                         _exit(255);
  73                 }
  74                 /* fork again to lose parent. */
  75                 cpid = fork();
  76                 if (cpid < 0) {
  77                         error("fork to lose parent failed: %s.", strerror(errno));
  78                         _exit(255);
  79                 }
  80                 if (cpid > 0)
  81                         _exit(0);
  82                 /* in grandchild here. */
  83
  84                 /*
  85                  * If we are rdist'ing to "localhost" as the same user
  86                  * as we are, then avoid running remote shell for efficiency.
  87                  */
  88                 if (strcmp(*ahost, "localhost") == 0 &&
  89                     strcmp(luser, ruser) == 0) {
  90                         execlp(_PATH_BSHELL, xbasename(_PATH_BSHELL), "-c",
  91                                cmd, NULL);
  92                         error("execlp %s failed: %s.", _PATH_BSHELL, strerror(errno));
  93                 } else {
  94                         execlp(path_rsh, xbasename(path_rsh),
  95                                *ahost, "-l", ruser, cmd, NULL);
  96                         error("execlp %s failed: %s.", path_rsh,
  97                                 strerror(errno));
  98                 }
  99                 _exit(255);
 100         }
 101         if (cpid > 0) {
 102                 /* parent. close sp[1], return sp[0]. */
 103                 close(sp[1]);
 104                 /* reap child. */
 105                 wait(0);
 106                 return sp[0];
 107         }
 108         /*NOTREACHED*/
 109         return (-1);
 110 }
 111
 112 #endif  /* !DIRECT_RCMD */