rcmd.c

Newlib 嵌入式 C库 标准实现代码

/*
 * Copyright (c) 1983, 1993, 1994
 *	The 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. 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.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)rcmd.c	8.3 (Berkeley) 3/26/94";
#endif /* LIBC_SCCS and not lint */
#include <sys/cdefs.h>
#include <sys/types.h>
#include <time.h>
#include <sys/select.h>

#include "namespace.h"
#include <sys/param.h>
#include <sys/socket.h>
#include <sys/stat.h>

#include <netinet/in.h>
#include <arpa/inet.h>

#include <signal.h>
#include <fcntl.h>
#include <netdb.h>
#include <stdlib.h>
#include <unistd.h>
#include <pwd.h>
#include <errno.h>
#include <stdio.h>
#include <ctype.h>
#include <string.h>
#ifdef YP
#include <rpc/rpc.h>
#include <rpcsvc/yp_prot.h>
#include <rpcsvc/ypclnt.h>
#endif
#include <arpa/nameser.h>
#include "un-namespace.h"

/* wrapper for KAME-special getnameinfo() */
#ifndef NI_WITHSCOPEID
#define NI_WITHSCOPEID	0
#endif

extern int innetgr( const char *, const char *, const char *, const char * );
extern int rcmdsh(char **ahost, int rport, const char *locuser, const char *remuser, const char *cmd, const char *rshprog);
int rresvport_af(int *alport, int family);

#define max(a, b)	((a > b) ? a : b)

int __ivaliduser(FILE *, u_int32_t, const char *, const char *);
int __ivaliduser_af(FILE *,const void *, const char *, const char *, int, int);
int __ivaliduser_sa(FILE *, const struct sockaddr *, socklen_t, const char *,
    const char *);
static int __icheckhost(const struct sockaddr *, socklen_t, const char *);

char paddr[NI_MAXHOST];

int
rcmd_af(ahost, rport, locuser, remuser, cmd, fd2p, af)
	char **ahost;
	u_short rport;
	const char *locuser, *remuser, *cmd;
	int *fd2p;
	int af;
{
	struct addrinfo hints, *res, *ai;
	struct sockaddr_storage from;
	fd_set reads;
	sigset_t oldmask, newmask;
	pid_t pid;
	int s, aport, lport, timo, error;
	char c, *p;
	int refused, nres;
	char num[8];
	static char canonnamebuf[MAXDNAME];	/* is it proper here? */

	/* call rcmdsh() with specified remote shell if appropriate. */
	if (!issetugid() && (p = getenv("RSH"))) {
		struct servent *sp = getservbyname("shell", "tcp");

		if (sp && sp->s_port == rport)
			return (rcmdsh(ahost, rport, locuser, remuser,
			    cmd, p));
	}

	/* use rsh(1) if non-root and remote port is shell. */
	if (geteuid()) {
		struct servent *sp = getservbyname("shell", "tcp");

		if (sp && sp->s_port == rport)
			return (rcmdsh(ahost, rport, locuser, remuser,
			    cmd, NULL));
	}

	pid = getpid();

	memset(&hints, 0, sizeof(hints));
	hints.ai_flags = AI_CANONNAME;
	hints.ai_family = af;
	hints.ai_socktype = SOCK_STREAM;
	hints.ai_protocol = 0;
	(void)snprintf(num, sizeof(num), "%d", ntohs(rport));
	error = getaddrinfo(*ahost, num, &hints, &res);
	if (error) {
		fprintf(stderr, "rcmd: getaddrinfo: %s\n",
			gai_strerror(error));
		if (error == EAI_SYSTEM)
			fprintf(stderr, "rcmd: getaddrinfo: %s\n",
				strerror(errno));
		return (-1);
	}

	if (res->ai_canonname
	 && strlen(res->ai_canonname) + 1 < sizeof(canonnamebuf)) {
		strncpy(canonnamebuf, res->ai_canonname, sizeof(canonnamebuf));
		*ahost = canonnamebuf;
	}
	nres = 0;
	for (ai = res; ai; ai = ai->ai_next)
		nres++;
	ai = res;
	refused = 0;
	sigemptyset(&newmask);
	sigaddset(&newmask, SIGURG);
	sigprocmask(SIG_BLOCK, (const sigset_t *)&newmask, &oldmask);
	for (timo = 1, lport = IPPORT_RESERVED - 1;;) {
		s = rresvport_af(&lport, ai->ai_family);
		if (s < 0) {
			if (errno != EAGAIN && ai->ai_next) {
				ai = ai->ai_next;
				continue;
			}
			if (errno == EAGAIN)
				(void)fprintf(stderr,
				    "rcmd: socket: All ports in use\n");
			else
				(void)fprintf(stderr, "rcmd: socket: %s\n",
				    strerror(errno));
			freeaddrinfo(res);
			sigprocmask(SIG_SETMASK, (const sigset_t *)&oldmask,
			    NULL);
			return (-1);
		}
		fcntl(s, F_SETOWN, pid);
		if (connect(s, ai->ai_addr, ai->ai_addrlen) >= 0)
			break;
		(void)close(s);
		if (errno == EADDRINUSE) {
			lport--;
			continue;
		}
		if (errno == ECONNREFUSED)
			refused = 1;
		if (ai->ai_next == NULL && (!refused || timo > 16)) {
			(void)fprintf(stderr, "%s: %s\n",
				      *ahost, strerror(errno));
			freeaddrinfo(res);
			sigprocmask(SIG_SETMASK, (const sigset_t *)&oldmask,
			    NULL);
			return (-1);
		}
		if (nres > 1) {
			int oerrno = errno;

			getnameinfo(ai->ai_addr, ai->ai_addrlen,
				    paddr, sizeof(paddr),
				    NULL, 0,
				    NI_NUMERICHOST|NI_WITHSCOPEID);
			(void)fprintf(stderr, "connect to address %s: ",
				      paddr);
			errno = oerrno;
			perror(0);
		}
		if ((ai = ai->ai_next) == NULL) {
			/* refused && timo <= 16 */
			struct timespec time_to_sleep, time_remaining;

			time_to_sleep.tv_sec = timo;
			time_to_sleep.tv_nsec = 0;
			(void)nanosleep(&time_to_sleep, &time_remaining);
			timo *= 2;
			ai = res;
			refused = 0;
		}
		if (nres > 1) {
			getnameinfo(ai->ai_addr, ai->ai_addrlen,
				    paddr, sizeof(paddr),
				    NULL, 0,
				    NI_NUMERICHOST|NI_WITHSCOPEID);
			fprintf(stderr, "Trying %s...\n", paddr);
		}
	}
	lport--;
	if (fd2p == 0) {
		write(s, "", 1);
		lport = 0;
	} else {
		char num[8];
		int s2 = rresvport_af(&lport, ai->ai_family), s3;
		int len = ai->ai_addrlen;
		int nfds;

		if (s2 < 0)
			goto bad;
		listen(s2, 1);
		(void)snprintf(num, sizeof(num), "%d", lport);
		if (write(s, num, strlen(num)+1) != strlen(num)+1) {
			(void)fprintf(stderr,
			    "rcmd: write (setting up stderr): %s\n",
			    strerror(errno));
			(void)close(s2);
			goto bad;
		}
		nfds = max(s, s2)+1;
		if(nfds > FD_SETSIZE) {
			fprintf(stderr, "rcmd: too many files\n");
			(void)close(s2);
			goto bad;
		}
again:
		FD_ZERO(&reads);
		FD_SET(s, &reads);
		FD_SET(s2, &reads);
		errno = 0;
		if (select(nfds, &reads, 0, 0, 0) < 1 || !FD_ISSET(s2, &reads)){
			if (errno != 0)
				(void)fprintf(stderr,
				    "rcmd: select (setting up stderr): %s\n",
				    strerror(errno));
			else
				(void)fprintf(stderr,
				"select: protocol failure in circuit setup\n");
			(void)close(s2);
			goto bad;
		}
		s3 = accept(s2, (struct sockaddr *)&from, &len);
		switch (from.ss_family) {
		case AF_INET:
			aport = ntohs(((struct sockaddr_in *)&from)->sin_port);
			break;
#ifdef INET6
		case AF_INET6:
			aport = ntohs(((struct sockaddr_in6 *)&from)->sin6_port);
			break;
#endif
		default:
			aport = 0;	/* error */
			break;
		}
		/*
		 * XXX careful for ftp bounce attacks. If discovered, shut them
		 * down and check for the real auxiliary channel to connect.
		 */
		if (aport == 20) {
			close(s3);
			goto again;
		}
		(void)close(s2);
		if (s3 < 0) {
			(void)fprintf(stderr,
			    "rcmd: accept: %s\n", strerror(errno));
			lport = 0;
			goto bad;
		}
		*fd2p = s3;
		if (aport >= IPPORT_RESERVED || aport < IPPORT_RESERVED / 2) {
			(void)fprintf(stderr,
			    "socket: protocol failure in circuit setup.\n");
			goto bad2;
		}
	}
	(void)write(s, locuser, strlen(locuser)+1);
	(void)write(s, remuser, strlen(remuser)+1);
	(void)write(s, cmd, strlen(cmd)+1);
	if (read(s, &c, 1) != 1) {
		(void)fprintf(stderr,
		    "rcmd: %s: %s\n", *ahost, strerror(errno));
		goto bad2;
	}
	if (c != 0) {
		while (read(s, &c, 1) == 1) {
			(void)write(STDERR_FILENO, &c, 1);
			if (c == '\n')
				break;
		}
		goto bad2;
	}
	sigprocmask(SIG_SETMASK, (const sigset_t *)&oldmask, NULL);
	freeaddrinfo(res);
	return (s);
bad2:
	if (lport)
		(void)close(*fd2p);
bad:
	(void)close(s);
	sigprocmask(SIG_SETMASK, (const sigset_t *)&oldmask, NULL);
	freeaddrinfo(res);
	return (-1);
}

int
rcmd(ahost, rport, locuser, remuser, cmd, fd2p)
	char **ahost;
	u_short rport;
	const char *locuser, *remuser, *cmd;
	int *fd2p;
{
	return rcmd_af(ahost, rport, locuser, remuser, cmd, fd2p, AF_INET);
}

int
rresvport(port)
	int *port;
{
	return rresvport_af(port, AF_INET);
}

int
rresvport_af(alport, family)
	int *alport, family;
{
	int s;
	struct sockaddr_storage ss;
	u_short *sport;

	memset(&ss, 0, sizeof(ss));
	ss.ss_family = family;
	switch (family) {
	case AF_INET:
		sport = &((struct sockaddr_in *)&ss)->sin_port;
		((struct sockaddr_in *)&ss)->sin_addr.s_addr = INADDR_ANY;
		break;
#ifdef INET6
	case AF_INET6:
		sport = &((struct sockaddr_in6 *)&ss)->sin6_port;
		((struct sockaddr_in6 *)&ss)->sin6_addr = in6addr_any;
		break;
#endif
	default:
		errno = EAFNOSUPPORT;
		return -1;
	}

	s = socket(ss.ss_family, SOCK_STREAM, 0);
	if (s < 0)
		return (-1);
#if 0 /* compat_exact_traditional_rresvport_semantics */
	sin.sin_port = htons((u_short)*alport);
	if (_bind(s, (struct sockaddr *)&sin, sizeof(sin)) >= 0)
		return (s);
	if (errno != EADDRINUSE) {
		(void)close(s);
		return (-1);
	}
#endif
	*sport = 0;
	if (bindresvport_sa(s, (struct sockaddr *)&ss) == -1) {
		(void)close(s);
		return (-1);
	}
	*alport = (int)ntohs(*sport);