dissertation/usr.bin/rdist/common.c

/*	$OpenBSD: common.c,v 1.40 2019/06/28 13:35:03 deraadt Exp $	*/

/*
 * Copyright (c) 1983 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/stat.h>
#include <sys/time.h>
#include <sys/wait.h>

#include <errno.h>
#include <fcntl.h>
#include <grp.h>
#include <limits.h>
#include <paths.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "defs.h"

/*
 * Things common to both the client and server.
 */

/*
 * Variables common to both client and server
 */
char			host[HOST_NAME_MAX+1];	/* Name of this host */
uid_t			userid = (uid_t)-1;	/* User's UID */
gid_t			groupid = (gid_t)-1;	/* User's GID */
gid_t		        gidset[NGROUPS_MAX];	/* User's GID list */
int			gidsetlen = 0;		/* Number of GIDS in list */
char		       *homedir = NULL;		/* User's $HOME */
char		       *locuser = NULL;		/* Local User's name */
int			isserver = FALSE;	/* We're the server */
int     		amchild = 0;		/* This PID is a child */
int			do_fork = 1;		/* Fork child process */
char		       *currenthost = NULL;	/* Current client hostname */
char		       *progname = NULL;	/* Name of this program */
int			rem_r = -1;		/* Client file descriptor */
int			rem_w = -1;		/* Client file descriptor */
volatile sig_atomic_t 	contimedout = FALSE;	/* Connection timed out */
int			rtimeout = RTIMEOUT;	/* Response time out */
jmp_buf			finish_jmpbuf;		/* Finish() jmp buffer */
int			setjmp_ok = FALSE;	/* setjmp()/longjmp() status */
char		      **realargv;		/* Real main() argv */
int			realargc;		/* Real main() argc */
opt_t			options = 0;		/* Global install options */
char			defowner[64] = "bin";	/* Default owner */
char			defgroup[64] = "bin";	/* Default group */

static int sendcmdmsg(int, char *, size_t);
static ssize_t remread(int, u_char *, size_t);
static int remmore(void);

/* 
 * Front end to write() that handles partial write() requests.
 */
ssize_t
xwrite(int fd, void *buf, size_t len)
{
    	size_t nleft = len;
	ssize_t nwritten;
	char *ptr = buf;
         
	while (nleft > 0) {
	    	if ((nwritten = write(fd, ptr, nleft)) <= 0) {
			return nwritten;
	    	}
	    	nleft -= nwritten;
	    	ptr += nwritten;
	}

	return len;
}

/*
 * Do run-time initialization
 */
int
init(int argc, char **argv, char **envp)
{
	struct passwd *pw;
	int i;

	/*
	 * Save a copy of our argc and argv before setargs() overwrites them
	 */
	realargc = argc;
	realargv = xmalloc(sizeof(char *) * (argc+1));
	for (i = 0; i < argc; i++)
		realargv[i] = xstrdup(argv[i]);

	pw = getpwuid(userid = getuid());
	if (pw == NULL) {
		error("Your user id (%u) is not known to this system.",
		      getuid());
		return(-1);
	}

	debugmsg(DM_MISC, "UserID = %u pwname = '%s' home = '%s'\n",
		 userid, pw->pw_name, pw->pw_dir);
	homedir = xstrdup(pw->pw_dir);
	locuser = xstrdup(pw->pw_name);
	groupid = pw->pw_gid;
	gidsetlen = getgroups(NGROUPS_MAX, gidset);
	gethostname(host, sizeof(host));
#if 0
	if ((cp = strchr(host, '.')) != NULL)
	    	*cp = CNULL;
#endif

	/*
	 * If we're not root, disable paranoid ownership checks
	 * since normal users cannot chown() files.
	 */
	if (!isserver && userid != 0) {
		FLAG_ON(options, DO_NOCHKOWNER);
		FLAG_ON(options, DO_NOCHKGROUP);
	}

	return(0);
}

/*
 * Finish things up before ending.
 */
void
finish(void)
{
	debugmsg(DM_CALL, 
		 "finish() called: do_fork = %d amchild = %d isserver = %d",
		 do_fork, amchild, isserver);
	cleanup(0);

	/*
	 * There's no valid finish_jmpbuf for the rdist master parent.
	 */
	if (!do_fork || amchild || isserver) {

		if (!setjmp_ok) {
#ifdef DEBUG_SETJMP
			error("attemping longjmp() without target");
			abort();
#else
			exit(1);
#endif
		}

		longjmp(finish_jmpbuf, 1);
		/*NOTREACHED*/
		error("Unexpected failure of longjmp() in finish()");
		exit(2);
	} else
		exit(1);
}

/*
 * Handle lost connections
 */
void
lostconn(void)
{
	/* Prevent looping */
	(void) signal(SIGPIPE, SIG_IGN);

	rem_r = rem_w = -1;	/* Ensure we don't try to send to server */
	checkhostname();
	error("Lost connection to %s", 
	      (currenthost) ? currenthost : "(unknown)");

	finish();
}

/*
 * General signal handler
 */
void
sighandler(int sig)
{
	int save_errno = errno;

	/* XXX signal race */
	debugmsg(DM_CALL, "sighandler() received signal %d\n", sig);

	switch (sig) {
	case SIGALRM:
		contimedout = TRUE;
		/* XXX signal race */
		checkhostname();
		error("Response time out");
		finish();
		break;

	case SIGPIPE:
		/* XXX signal race */
		lostconn();
		break;

	case SIGFPE:
		debug = !debug;
		break;

	case SIGHUP:
	case SIGINT:
	case SIGQUIT:
	case SIGTERM:
		/* XXX signal race */
		finish();
		break;

	default:
		/* XXX signal race */
		fatalerr("No signal handler defined for signal %d.", sig);
	}
	errno = save_errno;
}

/*
 * Function to actually send the command char and message to the
 * remote host.
 */
static int
sendcmdmsg(int cmd, char *msg, size_t msgsize)
{
	int len;

	if (rem_w < 0)
		return(-1);

	/*
	 * All commands except C_NONE should have a newline
	 */
	if (cmd != C_NONE && !strchr(msg + 1, '\n'))
		(void) strlcat(msg + 1, "\n", msgsize - 1);

	if (cmd == C_NONE)
		len = strlen(msg);
	else {
		len = strlen(msg + 1) + 1;
		msg[0] = cmd;
	}

	debugmsg(DM_PROTO, ">>> Cmd = %c (\\%3.3o) Msg = \"%.*s\"",
		 cmd, cmd, 
		 (cmd == C_NONE) ? len-1 : len-2,
		 (cmd == C_NONE) ? msg : msg + 1);

	return(!(xwrite(rem_w, msg, len) == len));
}

/*
 * Send a command message to the remote host.
 * Called as sendcmd(char cmdchar, char *fmt, arg1, arg2, ...)
 * The fmt may be NULL, in which case there are no args.
 */
int
sendcmd(char cmd, const char *fmt, ...)
{
	static char buf[BUFSIZ];
	va_list args;

	va_start(args, fmt);
	if (fmt)
		(void) vsnprintf(buf + (cmd != C_NONE),
				 sizeof(buf) - (cmd != C_NONE), fmt, args);
	else
		buf[1] = CNULL;
	va_end(args);

	return(sendcmdmsg(cmd, buf, sizeof(buf)));
}

/*
 * Internal variables and routines for reading lines from the remote.
 */
static u_char rembuf[BUFSIZ];
static u_char *remptr;
static ssize_t remleft;

#define remc() (--remleft < 0 ? remmore() : *remptr++)

/*
 * Back end to remote read()
 */
static ssize_t 
remread(int fd, u_char *buf, size_t bufsiz)
{
	return(read(fd, (char *)buf, bufsiz));
}

static int
remmore(void)
{
	(void) signal(SIGALRM, sighandler);
	(void) alarm(rtimeout);

	remleft = remread(rem_r, rembuf, sizeof(rembuf));

	(void) alarm(0);

	if (remleft < 0)
		return (-2);	/* error */
	if (remleft == 0)
		return (-1);	/* EOF */
	remptr = rembuf;
	remleft--;
	return (*remptr++);
}
	
/*
 * Read an input line from the remote.  Return the number of bytes
 * stored (equivalent to strlen(p)).  If `cleanup' is set, EOF at
 * the beginning of a line is returned as EOF (-1); other EOFs, or
 * errors, call cleanup() or lostconn().  In other words, unless
 * the third argument is nonzero, this routine never returns failure.
 */
int
remline(u_char *buffer, int space, int doclean)
{
	int c, left = space;
	u_char *p = buffer;

	if (rem_r < 0) {
		error("Cannot read remote input: Remote descriptor not open.");
		return(-1);
	}

	while (left > 0) {
		if ((c = remc()) < -1) {	/* error */
			if (doclean) {
				finish();
				/*NOTREACHED*/
			}
			lostconn();
			/*NOTREACHED*/
		}
		if (c == -1) {			/* got EOF */
			if (doclean) {
				if (left == space)
					return (-1);/* signal proper EOF */
				finish();	/* improper EOF */
				/*NOTREACHED*/
			}
			lostconn();
			/*NOTREACHED*/
		}
		if (c == '\n') {
			*p = CNULL;

			if (debug) {
				static char mbuf[BUFSIZ];

				(void) snprintf(mbuf, sizeof(mbuf),
					"<<< Cmd = %c (\\%3.3o) Msg = \"%s\"", 
					       buffer[0], buffer[0], 
					       buffer + 1);

				debugmsg(DM_PROTO, "%s", mbuf);
			}

			return (space - left);
		}
		*p++ = c;
		left--;
	}

	/* this will probably blow the entire session */
	error("remote input line too long");
	p[-1] = CNULL;		/* truncate */
	return (space);
}

/*
 * Non-line-oriented remote read.
 */
ssize_t
readrem(char *p, ssize_t space)
{
	if (remleft <= 0) {
		/*
		 * Set remote time out alarm.
		 */
		(void) signal(SIGALRM, sighandler);
		(void) alarm(rtimeout);

		remleft = remread(rem_r, rembuf, sizeof(rembuf));

		(void) alarm(0);
		remptr = rembuf;
	}

	if (remleft <= 0)
		return (remleft);
	if (remleft < space)
		space = remleft;

	memcpy(p, remptr, space);

	remptr += space;
	remleft -= space;

	return (space);
}

/*
 * Get the user name for the uid.
 */
char *
getusername(uid_t uid, char *file, opt_t opts)
{
	static char buf[100];
	static uid_t lastuid = (uid_t)-1;
	const char *name;

	/*
	 * The value of opts may have changed so we always
	 * do the opts check.
	 */
  	if (IS_ON(opts, DO_NUMCHKOWNER)) { 
		(void) snprintf(buf, sizeof(buf), ":%u", uid);
		return(buf);
  	}

	/*
	 * Try to avoid passwd lookup.
	 */
	if (lastuid == uid && buf[0] != '\0' && buf[0] != ':')
		return(buf);

	lastuid = uid;

	if ((name = user_from_uid(uid, 1)) == NULL) {
		if (IS_ON(opts, DO_DEFOWNER) && !isserver) 
			(void) strlcpy(buf, defowner, sizeof(buf));
		else {
			message(MT_WARNING,
				"%s: No password entry for uid %u", file, uid);
			(void) snprintf(buf, sizeof(buf), ":%u", uid);
		}
	} else {
		(void) strlcpy(buf, name, sizeof(buf));
	}

	return(buf);
}

/*
 * Get the group name for the gid.
 */
char *
getgroupname(gid_t gid, char *file, opt_t opts)
{
	static char buf[100];
	static gid_t lastgid = (gid_t)-1;
	const char *name;

	/*
	 * The value of opts may have changed so we always
	 * do the opts check.
	 */
  	if (IS_ON(opts, DO_NUMCHKGROUP)) { 
		(void) snprintf(buf, sizeof(buf), ":%u", gid);
		return(buf);
  	}

	/*
	 * Try to avoid group lookup.
	 */
	if (lastgid == gid && buf[0] != '\0' && buf[0] != ':')
		return(buf);

	lastgid = gid;

	if ((name = group_from_gid(gid, 1)) == NULL) {
		if (IS_ON(opts, DO_DEFGROUP) && !isserver) 
			(void) strlcpy(buf, defgroup, sizeof(buf));
		else {
			message(MT_WARNING, "%s: No name for group %u",
				file, gid);
			(void) snprintf(buf, sizeof(buf), ":%u", gid);
		}
	} else
		(void) strlcpy(buf, name, sizeof(buf));

	return(buf);
}

/*
 * Read a response from the remote host.
 */
int
response(void)
{
	static u_char resp[BUFSIZ];
	u_char *s;
	int n;

	debugmsg(DM_CALL, "response() start\n");

	n = remline(s = resp, sizeof(resp), 0);

	n--;
	switch (*s++) {
        case C_ACK:
		debugmsg(DM_PROTO, "received ACK\n");
		return(0);
	case C_LOGMSG:
		if (n > 0) {
			message(MT_CHANGE, "%s", s);
			return(1);
		}
		debugmsg(DM_PROTO, "received EMPTY logmsg\n");
		return(0);
	case C_NOTEMSG:
		if (s)
			message(MT_NOTICE, "%s", s);
		return(response());

	default:
		s--;
		n++;
		/* fall into... */

	case C_ERRMSG:	/* Normal error message */
		if (s)
			message(MT_NERROR, "%s", s);
		return(-1);

	case C_FERRMSG:	/* Fatal error message */
		if (s)
			message(MT_FERROR, "%s", s);
		finish();
		return(-1);
	}
	/*NOTREACHED*/
}

/*
 * This should be in expand.c but the other routines call other modules
 * that we don't want to load in.
 *
 * Expand file names beginning with `~' into the
 * user's home directory path name. Return a pointer in buf to the
 * part corresponding to `file'.
 */
char *
exptilde(char *ebuf, char *file, size_t ebufsize)
{
	struct passwd *pw;
	char *pw_dir, *rest;
	static char lastuser[_PW_NAME_LEN + 1];
	static char lastdir[PATH_MAX];
	size_t len;

	if (*file != '~') {
notilde:
		(void) strlcpy(ebuf, file, ebufsize);
		return(ebuf);
	}
	pw_dir = homedir;
	if (*++file == CNULL) {
		rest = NULL;
	} else if (*file == '/') {
		rest = file;
	} else {
		rest = file;
		while (*rest && *rest != '/')
			rest++;
		if (*rest == '/')
			*rest = CNULL;
		else
			rest = NULL;
		if (strcmp(locuser, file) != 0) {
			if (strcmp(lastuser, file) != 0) {
				if ((pw = getpwnam(file)) == NULL) {
					error("%s: unknown user name", file);
					if (rest != NULL)
						*rest = '/';
					return(NULL);
				}
				strlcpy(lastuser, pw->pw_name, sizeof(lastuser));
				strlcpy(lastdir, pw->pw_dir, sizeof(lastdir));
			}
			pw_dir = lastdir;
		}
		if (rest != NULL)
			*rest = '/';
	}
	if ((len = strlcpy(ebuf, pw_dir, ebufsize)) >= ebufsize)
		goto notilde;
	pw_dir = ebuf + len;
	if (rest != NULL) {
		pw_dir++;
		if ((len = strlcat(ebuf, rest, ebufsize)) >= ebufsize)
			goto notilde;
	}
	return(pw_dir);
}



/*
 * Set access and modify times of a given file
 */
int
setfiletime(char *file, time_t atime, time_t mtime)
{
	struct timeval tv[2];

	if (atime != 0 && mtime != 0) {
		tv[0].tv_sec = atime;
		tv[1].tv_sec = mtime;
		tv[0].tv_usec = tv[1].tv_usec = 0;
		return (utimes(file, tv));
	} else	/* Set to current time */
		return (utimes(file, NULL));
}

/*
 * Get version info
 */
char *
getversion(void)
{
	static char buff[BUFSIZ];

	(void) snprintf(buff, sizeof(buff), 
	"Version %s.%d (%s) - Protocol Version %d, Release %s, Patch level %d",
		       DISTVERSION, PATCHLEVEL, DISTSTATUS,
		       VERSION, DISTVERSION, PATCHLEVEL);

	return(buff);
}

/*
 * Execute a shell command to handle special cases.
 * This is now common to both server and client
 */
void
runcommand(char *cmd)
{
	ssize_t nread;
	pid_t pid, wpid;
	char *cp, *s;
	char sbuf[BUFSIZ], buf[BUFSIZ];
	int fd[2], status;

	if (pipe(fd) == -1) {
		error("pipe of %s failed: %s", cmd, SYSERR);
		return;
	}

	if ((pid = fork()) == 0) {
		/*
		 * Return everything the shell commands print.
		 */
		(void) close(0);
		(void) close(1);
		(void) close(2);
		(void) open(_PATH_DEVNULL, O_RDONLY);
		(void) dup(fd[PIPE_WRITE]);
		(void) dup(fd[PIPE_WRITE]);
		(void) close(fd[PIPE_READ]);
		(void) close(fd[PIPE_WRITE]);
		(void) execl(_PATH_BSHELL, "sh", "-c", cmd, (char *)NULL);
		_exit(127);
	}
	(void) close(fd[PIPE_WRITE]);
	s = sbuf;
	*s++ = C_LOGMSG;
	while ((nread = read(fd[PIPE_READ], buf, sizeof(buf))) > 0) {
		cp = buf;
		do {
			*s++ = *cp++;
			if (cp[-1] != '\n') {
				if (s < (char *) &sbuf[sizeof(sbuf)-1])
					continue;
				*s++ = '\n';
			}
			/*
			 * Throw away blank lines.
			 */
			if (s == &sbuf[2]) {
				s--;
				continue;
			}
			if (isserver)
				(void) xwrite(rem_w, sbuf, s - sbuf);
			else {
				*s = CNULL;
				message(MT_INFO, "%s", sbuf+1);
			}
			s = &sbuf[1];
		} while (--nread);
	}
	if (s > (char *) &sbuf[1]) {
		*s++ = '\n';
		if (isserver)
			(void) xwrite(rem_w, sbuf, s - sbuf);
		else {
			*s = CNULL;
			message(MT_INFO, "%s", sbuf+1);
		}
	}
	while ((wpid = wait(&status)) != pid && wpid != -1)
		;
	if (wpid == -1)
		status = -1;
	(void) close(fd[PIPE_READ]);
	if (status)
		error("shell returned %d", status);
	else if (isserver)
		ack();
}

/*
 * Malloc with error checking
 */
void *
xmalloc(size_t amt)
{
	void *ptr;

	if ((ptr = malloc(amt)) == NULL)
		fatalerr("Cannot malloc %zu bytes of memory.", amt);

	return (ptr);
}

/*
 * realloc with error checking
 */
void *
xrealloc(void *baseptr, size_t amt)
{
	void *new;

	if ((new = realloc(baseptr, amt)) == NULL)
		fatalerr("Cannot realloc %zu bytes of memory.", amt);

	return (new);
}

/*
 * calloc with error checking
 */
void *
xcalloc(size_t num, size_t esize)
{
	void *ptr;

	if ((ptr = calloc(num, esize)) == NULL)
		fatalerr("Cannot calloc %zu * %zu = %zu bytes of memory.",
		      num, esize, num * esize);

	return (ptr);
}

/*
 * Strdup with error checking
 */
char *
xstrdup(const char *str)
{
	size_t len = strlen(str) + 1;
	char *nstr = xmalloc(len);

	return (memcpy(nstr, str, len));
}

/*
 * Private version of basename()
 */
char *
xbasename(char *path)
{
	char *cp;
 
	if ((cp = strrchr(path, '/')) != NULL)
		return(cp+1);
	else
		return(path);
}

/*
 * Take a colon (':') separated path to a file and
 * search until a component of that path is found and
 * return the found file name.
 */
char *
searchpath(char *path)
{
	char *file;
	char *space;
	int found;
	struct stat statbuf;

	for (found = 0; !found && (file = strsep(&path, ":")) != NULL; ) {
		if ((space = strchr(file, ' ')) != NULL)
			*space = CNULL;
		found = stat(file, &statbuf) == 0;
		if (space)
			*space = ' ';		/* Put back what we zapped */
	}
	return (file);
}