ftpd.c

伯克利大学的一个ftp协议的实现源代码,包括客户端和服务器端.

/*
 * Copyright (c) 1985, 1988, 1990, 1992, 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.
 */

/* 
 * From: @(#)ftpd.c	8.4 (Berkeley) 4/16/94
 * From: NetBSD: ftpd.c,v 1.15 1995/06/03 22:46:47 mycroft Exp
 * From: OpenBSD: ftpd.c,v 1.26 1996/12/07 09:00:22 bitblt Exp
 * From: OpenBSD: ftpd.c,v 1.35 1997/05/01 14:45:37 deraadt Exp
 */
char ftpd_rcsid[] = 
  "$Id: ftpd.c,v 1.8 1997/06/09 01:04:59 dholland Exp $";

char copyright[] =
  "@(#) Copyright (c) 1985, 1988, 1990, 1992, 1993, 1994\n"
  "     The Regents of the University of California.  All rights reserved.\n";

/*
 * FTP server.
 */
#include <sys/param.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <sys/mman.h>

#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/tcp.h>

#define	FTP_NAMES
#include <arpa/ftp.h>
#include <arpa/inet.h>
#include <arpa/telnet.h>

#include <ctype.h>
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <glob.h>
#include <limits.h>
#include <netdb.h>
#include <pwd.h>
#include <setjmp.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <time.h>
#include <vis.h>
#include <unistd.h>
#include <utmp.h>
#ifndef __linux__
#include <err.h>
#else
#include <grp.h>       /* for initgroups() */
#include <sys/file.h>  /* for L_SET et al. */
typedef int64_t quad_t;
#endif

#ifndef MAP_FAILED
#define MAP_FAILED ((void *)-1)
#endif

#ifdef USE_SHADOW
#include <shadow.h>
#include "isexpired.h"
#endif

#include "pathnames.h"
#include "extern.h"

#if __STDC__
#include <stdarg.h>
#else
#include <varargs.h>
#endif

static char version[] = "Version 6.2/OpenBSD/Linux-0.10";

extern	off_t restart_point;
extern	char cbuf[];

struct	sockaddr_in server_addr;
struct	sockaddr_in ctrl_addr;
struct	sockaddr_in data_source;
struct	sockaddr_in data_dest;
struct	sockaddr_in his_addr;
struct	sockaddr_in pasv_addr;

int	daemon_mode = 0;
int	data;
jmp_buf	errcatch, urgcatch;
int	logged_in;
struct	passwd *pw;
#ifdef USE_SHADOW
struct	spwd *spw = NULL;
#endif
int	debug = 0;
int	timeout = 900;    /* timeout after 15 minutes of inactivity */
int	maxtimeout = 7200;/* don't allow idle time to be set beyond 2 hours */
int	logging;
int	high_data_ports = 0;
int	anon_only = 0;
int	multihome = 0;
int	guest;
int	stats;
int	statfd = -1;
int	dochroot;
int	type;
int	form;
int	stru;			/* avoid C keyword */
int	mode;
int	doutmp = 0;		/* update utmp file */
int	usedefault = 1;		/* for data transfers */
int	pdata = -1;		/* for passive mode */
sig_atomic_t transflag;
off_t	file_size;
off_t	byte_count;
#if !defined(CMASK) || CMASK == 0
#undef CMASK
#define CMASK 027
#endif
int	defumask = CMASK;		/* default umask value */
char	tmpline[7];
char	hostname[MAXHOSTNAMELEN];
char	remotehost[MAXHOSTNAMELEN];
char	dhostname[MAXHOSTNAMELEN];
char	*guestpw;
static char ttyline[20];
char	*tty = ttyline;		/* for klogin */
static struct utmp utmp;	/* for utmp */

#if defined(KERBEROS)
int	notickets = 1;
char	*krbtkfile_env = NULL;
#endif

char	*ident = NULL;


/*
 * Timeout intervals for retrying connections
 * to hosts that don't accept PORT cmds.  This
 * is a kludge, but given the problems with TCP...
 */
#define	SWAITMAX	90	/* wait at most 90 seconds */
#define	SWAITINT	5	/* interval between retries */

int	swaitmax = SWAITMAX;
int	swaitint = SWAITINT;

#ifdef HASSETPROCTITLE
char	proctitle[BUFSIZ];	/* initial part of title */
#endif /* HASSETPROCTITLE */

#define LOGCMD(cmd, file) \
	if (logging > 1) \
	    syslog(LOG_INFO,"%s %s%s", cmd, \
		*(file) == '/' ? "" : curdir(), file);
#define LOGCMD2(cmd, file1, file2) \
	 if (logging > 1) \
	    syslog(LOG_INFO,"%s %s%s %s%s", cmd, \
		*(file1) == '/' ? "" : curdir(), file1, \
		*(file2) == '/' ? "" : curdir(), file2);
#define LOGBYTES(cmd, file, cnt) \
	if (logging > 1) { \
		if (cnt == (off_t)-1) \
		    syslog(LOG_INFO,"%s %s%s", cmd, \
			*(file) == '/' ? "" : curdir(), file); \
		else \
		    syslog(LOG_INFO, "%s %s%s = %qd bytes", cmd, \
			*(file) == '/' ? "" : curdir(), file, (quad_t)(cnt)); \
	}

static void	 ack __P((const char *));
static void	 myoob __P((int));
static int	 checkuser __P((const char *, const char *));
static FILE	*dataconn __P((const char *, off_t, const char *));
static void	 dolog __P((struct sockaddr_in *));
static const char	*curdir __P((void));
static void	 end_login __P((void));
static FILE	*getdatasock __P((const char *));
static int	guniquefd __P((const char *, char **));
static void	 lostconn __P((int));
static void	 sigquit __P((int));
static int	 receive_data __P((FILE *, FILE *));
static void	 send_data __P((FILE *, FILE *, off_t, off_t, int));
static struct passwd *
		 sgetpwnam __P((const char *));
static char	*sgetsave __P((char *));
static void	 reapchild __P((int));

void	 logxfer __P((const char *, off_t, time_t));

#ifdef __linux__
static void warnx(const char *format, ...) 
{
	va_list ap;
	va_start(ap, format);
	fprintf(stderr, "ftpd: ");
	vfprintf(stderr, format, ap);
	fprintf(stderr, "\n");
	va_end(ap);
}
#endif /* __linux__ */

static const char *
curdir(void)
{
	static char path[MAXPATHLEN+1+1];	/* path + '/' + '\0' */

	if (getcwd(path, sizeof(path)-2) == NULL)
		return ("");
	if (path[1] != '\0')		/* special case for root dir. */
		strcat(path, "/");
	/* For guest account, skip / since it's chrooted */
	return (guest ? path+1 : path);
}

int
main(int argc, char *argv[], char **envp)
{
	int addrlen, ch, on = 1, tos;
	char *cp, line[LINE_MAX];
	FILE *fd;
	const char *argstr = "AdDhlMSt:T:u:Uv";
	struct hostent *hp;
	void (*sigreturn)(int);

	initsetproctitle(argc, argv, envp);

	tzset();	/* in case no timezone database in ~ftp */

	/* set this here so klogin can use it... */
	(void)snprintf(ttyline, sizeof(ttyline), "ftp%d", getpid());

	while ((ch = getopt(argc, argv, argstr)) != -1) {
		switch (ch) {
		case 'A':
			anon_only = 1;
			break;

		case 'd':
			debug = 1;
			break;

		case 'D':
			daemon_mode = 1;
			break;

		case 'h':
			high_data_ports = 1;
			break;

		case 'l':
			logging++;	/* > 1 == extra logging */
			break;

		case 'M':
			multihome = 1;
			break;

		case 'S':
			stats = 1;
			break;

		case 't':
			timeout = atoi(optarg);
			if (maxtimeout < timeout)
				maxtimeout = timeout;
			break;

		case 'T':
			maxtimeout = atoi(optarg);
			if (timeout > maxtimeout)
				timeout = maxtimeout;
			break;

		case 'u':
		    {
			long val = 0;

			val = strtol(optarg, &optarg, 8);
			if (*optarg != '\0' || val < 0)
				warnx("bad value for -u");
			else
				defumask = val;
			break;
		    }

		case 'U':
			doutmp = 1;
			break;

		case 'v':
			debug = 1;
			break;

		default:
			warnx("unknown flag -%c ignored", optopt);
			break;
		}
	}

	(void) freopen(_PATH_DEVNULL, "w", stderr);

	/*
	 * LOG_NDELAY sets up the logging connection immediately,
	 * necessary for anonymous ftp's that chroot and can't do it later.
	 */
#ifndef LOG_FTP
#define LOG_FTP LOG_DAEMON
#endif
	openlog("ftpd", LOG_PID | LOG_NDELAY, LOG_FTP);

	if (daemon_mode) {
		int ctl_sock, fd2;
		struct servent *sv;

		/*
		 * Detach from parent.
		 */
		if (daemon(1, 1) < 0) {
			syslog(LOG_ERR, "failed to become a daemon");
			exit(1);
		}
		(void) signal(SIGCHLD, reapchild);
		/*
		 * Get port number for ftp/tcp.
		 */
		sv = getservbyname("ftp", "tcp");
		if (sv == NULL) {
			syslog(LOG_ERR, "getservbyname for ftp failed");
			exit(1);
		}
		/*
		 * Open a socket, bind it to the FTP port, and start
		 * listening.
		 */
		ctl_sock = socket(AF_INET, SOCK_STREAM, 0);
		if (ctl_sock < 0) {
			syslog(LOG_ERR, "control socket: %m");
			exit(1);
		}
		if (setsockopt(ctl_sock, SOL_SOCKET, SO_REUSEADDR,
		    (char *)&on, sizeof(on)) < 0)
			syslog(LOG_ERR, "control setsockopt: %m");;
		server_addr.sin_family = AF_INET;
		server_addr.sin_addr.s_addr = INADDR_ANY;
		server_addr.sin_port = sv->s_port;
		if (bind(ctl_sock, (struct sockaddr *)&server_addr,
			 sizeof(server_addr))) {
			syslog(LOG_ERR, "control bind: %m");
			exit(1);
		}
		if (listen(ctl_sock, 32) < 0) {
			syslog(LOG_ERR, "control listen: %m");
			exit(1);
		}
		/*
		 * Loop forever accepting connection requests and forking off
		 * children to handle them.
		 */
		while (1) {
			addrlen = sizeof(his_addr);
			fd2 = accept(ctl_sock, (struct sockaddr *)&his_addr,
				    &addrlen);
			if (fork() == 0) {
				/* child */
				(void) dup2(fd2, 0);
				(void) dup2(fd2, 1);
				close(ctl_sock);
				break;
			}
			close(fd2);
		}
	} else {
		addrlen = sizeof(his_addr);
		if (getpeername(0, (struct sockaddr *)&his_addr,
			        &addrlen) < 0) {
			syslog(LOG_ERR, "getpeername (%s): %m", argv[0]);
			exit(1);
		}
	}

	(void) signal(SIGHUP, sigquit);
	(void) signal(SIGINT, sigquit);
	(void) signal(SIGQUIT, sigquit);
	(void) signal(SIGTERM, sigquit);
	(void) signal(SIGPIPE, lostconn);
	(void) signal(SIGCHLD, SIG_IGN);
	sigreturn = signal(SIGURG, myoob);
	if ((long)sigreturn < 0)
		syslog(LOG_ERR, "signal: %m");

	addrlen = sizeof(ctrl_addr);
	if (getsockname(0, (struct sockaddr *)&ctrl_addr, &addrlen) < 0) {
		syslog(LOG_ERR, "getsockname (%s): %m", argv[0]);
		exit(1);
	}
#ifdef IP_TOS
	tos = IPTOS_LOWDELAY;
	if (setsockopt(0, IPPROTO_IP, IP_TOS, (char *)&tos, sizeof(int)) < 0)
		syslog(LOG_WARNING, "setsockopt (IP_TOS): %m");
#endif
	data_source.sin_port = htons(ntohs(ctrl_addr.sin_port) - 1);

	/* Try to handle urgent data inline */
#ifdef SO_OOBINLINE
	if (setsockopt(0, SOL_SOCKET, SO_OOBINLINE, (char *)&on, sizeof(on)) < 0)
		syslog(LOG_ERR, "setsockopt: %m");
#endif

#ifdef	F_SETOWN
	if (fcntl(fileno(stdin), F_SETOWN, getpid()) == -1)
		syslog(LOG_ERR, "fcntl F_SETOWN: %m");
#endif
	dolog(&his_addr);
	/*
	 * Set up default state
	 */
	data = -1;
	type = TYPE_A;
	form = FORM_N;
	stru = STRU_F;
	mode = MODE_S;
	tmpline[0] = '\0';

	/* If logins are disabled, print out the message. */
	if ((fd = fopen(_PATH_NOLOGIN,"r")) != NULL) {
		while (fgets(line, sizeof(line), fd) != NULL) {
			if ((cp = strchr(line, '\n')) != NULL)
				*cp = '\0';
			lreply(530, "%s", line);
		}
		(void) fflush(stdout);
		(void) fclose(fd);
		reply(530, "System not available.");
		exit(0);
	}
	if ((fd = fopen(_PATH_FTPWELCOME, "r")) != NULL) {
		while (fgets(line, sizeof(line), fd) != NULL) {
			if ((cp = strchr(line, '\n')) != NULL)
				*cp = '\0';
			lreply(220, "%s", line);
		}
		(void) fflush(stdout);
		(void) fclose(fd);
		/* reply(220,) must follow */
	}
	(void) gethostname(hostname, sizeof(hostname));

	/* Make sure hostname is fully qualified. */
	hp = gethostbyname(hostname);
	if (hp != NULL)
		strcpy (hostname, hp->h_name);

	if (multihome) {
		hp = gethostbyaddr((char *) &ctrl_addr.sin_addr,
				   sizeof (struct in_addr), AF_INET);
		if (hp != NULL) {
			strcpy (dhostname, hp->h_name);
		} else {
			/* Default. */
			strcpy (dhostname, inet_ntoa(ctrl_addr.sin_addr));
		}
	}

	reply(220, "%s FTP server (%s) ready.",
	      (multihome ? dhostname : hostname), version);
	(void) setjmp(errcatch);
	for (;;)
		(void) yyparse();
	/* NOTREACHED */
}

/*
 * Signal handlers.
 */

static void
lostconn(int signo)
{
	(void)signo;

	if (debug)
		syslog(LOG_DEBUG, "lost connection");
	dologout(-1);
}

static void
sigquit(signo)
	int signo;
{
	syslog(LOG_ERR, "got signal %s", strsignal(signo));

	dologout(-1);
}

/*
 * Helper function for sgetpwnam().
 */
static char *
sgetsave(s)
	char *s;
{
	char *new = malloc((unsigned) strlen(s) + 1);

	if (new == NULL) {
		perror_reply(421, "Local resource failure: malloc");
		dologout(1);
		/* NOTREACHED */
	}
	(void) strcpy(new, s);