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.

	}
	(void) fclose(din);
	data = -1;
	pdata = -1;
done:
	LOGBYTES(*mode == 'w' ? "put" : "append", name, byte_count);
	(*closefunc)(fout);
}

static FILE *
getdatasock(mode)
	const char *mode;
{
	int on = 1, s, t, tries;
	sigset_t allsigs;

	if (data >= 0)
		return (fdopen(data, mode));
	sigfillset(&allsigs);
	sigprocmask (SIG_BLOCK, &allsigs, NULL);
	(void) seteuid((uid_t)0);
	s = socket(AF_INET, SOCK_STREAM, 0);
	if (s < 0)
		goto bad;
	if (setsockopt(s, SOL_SOCKET, SO_REUSEADDR,
	    (char *) &on, sizeof(on)) < 0)
		goto bad;
	/* anchor socket to avoid multi-homing problems */
#ifndef __linux__
	data_source.sin_len = sizeof(struct sockaddr_in);
#endif
	data_source.sin_family = AF_INET;
	data_source.sin_addr = ctrl_addr.sin_addr;
	for (tries = 1; ; tries++) {
		if (bind(s, (struct sockaddr *)&data_source,
		    sizeof(data_source)) >= 0)
			break;
		if (errno != EADDRINUSE || tries > 10)
			goto bad;
		sleep(tries);
	}
	(void) seteuid((uid_t)pw->pw_uid);
	sigfillset(&allsigs);
	sigprocmask (SIG_UNBLOCK, &allsigs, NULL);

#ifdef IP_TOS
	on = IPTOS_THROUGHPUT;
	if (setsockopt(s, IPPROTO_IP, IP_TOS, (char *)&on, sizeof(int)) < 0)
		syslog(LOG_WARNING, "setsockopt (IP_TOS): %m");
#endif
#ifdef TCP_NOPUSH
	/*
	 * Turn off push flag to keep sender TCP from sending short packets
	 * at the boundaries of each write().  Should probably do a SO_SNDBUF
	 * to set the send buffer size as well, but that may not be desirable
	 * in heavy-load situations.
	 */
	on = 1;
	if (setsockopt(s, IPPROTO_TCP, TCP_NOPUSH, (char *)&on, sizeof on) < 0)
		syslog(LOG_WARNING, "setsockopt (TCP_NOPUSH): %m");
#endif
#ifdef SO_SNDBUF
	on = 65536;
	if (setsockopt(s, SOL_SOCKET, SO_SNDBUF, (char *)&on, sizeof on) < 0)
		syslog(LOG_WARNING, "setsockopt (SO_SNDBUF): %m");
#endif

	return (fdopen(s, mode));
bad:
	/* Return the real value of errno (close may change it) */
	t = errno;
	(void) seteuid((uid_t)pw->pw_uid);
	sigfillset (&allsigs);
	sigprocmask (SIG_UNBLOCK, &allsigs, NULL);
	(void) close(s);
	errno = t;
	return (NULL);
}

static FILE *
dataconn(name, size, mode)
	const char *name;
	off_t size;
	const char *mode;
{
	char sizebuf[32];
	FILE *file;
	int retry = 0, tos;

	file_size = size;
	byte_count = 0;
	if (size != (off_t) -1) {
		(void) snprintf(sizebuf, sizeof(sizebuf), " (%qd bytes)", 
				(quad_t) size);
	} else
		sizebuf[0] = '\0';
	if (pdata >= 0) {
		struct sockaddr_in from;
		int s, fromlen = sizeof(from);

		signal (SIGALRM, toolong);
		(void) alarm ((unsigned) timeout);
		s = accept(pdata, (struct sockaddr *)&from, &fromlen);
		(void) alarm (0);
		if (s < 0) {
			reply(425, "Can't open data connection.");
			(void) close(pdata);
			pdata = -1;
			return (NULL);
		}
		if (ntohs(from.sin_port) < IPPORT_RESERVED) {
			perror_reply(425, "Can't build data connection");
			(void) close(pdata);
			(void) close(s);
			pdata = -1;
			return (NULL);
		}
		if (from.sin_addr.s_addr != his_addr.sin_addr.s_addr) {
			perror_reply(435, "Can't build data connection"); 
			(void) close(pdata);
			(void) close(s);
			pdata = -1;
			return (NULL);
		}
		(void) close(pdata);
		pdata = s;
#ifdef IP_TOS
		tos = IPTOS_THROUGHPUT;
		(void) setsockopt(s, IPPROTO_IP, IP_TOS, (char *)&tos,
		    sizeof(int));
#endif
		reply(150, "Opening %s mode data connection for '%s'%s.",
		     type == TYPE_A ? "ASCII" : "BINARY", name, sizebuf);
		return (fdopen(pdata, mode));
	}
	if (data >= 0) {
		reply(125, "Using existing data connection for '%s'%s.",
		    name, sizebuf);
		usedefault = 1;
		return (fdopen(data, mode));
	}
	if (usedefault)
		data_dest = his_addr;
	usedefault = 1;
	file = getdatasock(mode);
	if (file == NULL) {
		reply(425, "Can't create data socket (%s,%d): %s.",
		    inet_ntoa(data_source.sin_addr),
		    ntohs(data_source.sin_port), strerror(errno));
		return (NULL);
	}
	data = fileno(file);

	/*
	 * attempt to connect to reserved port on client machine;
	 * this looks like an attack
	 */
	if (ntohs(data_dest.sin_port) < IPPORT_RESERVED ||
	    ntohs(data_dest.sin_port) == 2049) {		/* XXX */
		perror_reply(425, "Can't build data connection");
		(void) fclose(file);
		data = -1;
		return NULL;
	}
	if (data_dest.sin_addr.s_addr != his_addr.sin_addr.s_addr) {
		perror_reply(435, "Can't build data connection");
		(void) fclose(file);
		data = -1;
		return NULL;
	}
	while (connect(data, (struct sockaddr *)&data_dest,
	    sizeof(data_dest)) < 0) {
		if (errno == EADDRINUSE && retry < swaitmax) {
			sleep((unsigned) swaitint);
			retry += swaitint;
			continue;
		}
		perror_reply(425, "Can't build data connection");
		(void) fclose(file);
		data = -1;
		return (NULL);
	}
	reply(150, "Opening %s mode data connection for '%s'%s.",
	     type == TYPE_A ? "ASCII" : "BINARY", name, sizebuf);
	return (file);
}

/*
 * Tranfer the contents of "instr" to "outstr" peer using the appropriate
 * encapsulation of the data subject to Mode, Structure, and Type.
 *
 * NB: Form isn't handled.
 */
static void
send_data(instr, outstr, blksize, filesize, isreg)
	FILE *instr, *outstr;
	off_t blksize;
	off_t filesize;
	int isreg;
{
	int c, cnt, filefd, netfd;
	char *buf, *bp;
	size_t len;

	transflag++;
	if (setjmp(urgcatch)) {
		transflag = 0;
		return;
	}
	switch (type) {

	case TYPE_A:
		while ((c = getc(instr)) != EOF) {
			byte_count++;
			if (c == '\n') {
				if (ferror(outstr))
					goto data_err;
				(void) putc('\r', outstr);
			}
			(void) putc(c, outstr);
		}
		fflush(outstr);
		transflag = 0;
		if (ferror(instr))
			goto file_err;
		if (ferror(outstr))
			goto data_err;
		reply(226, "Transfer complete.");
		return;

	case TYPE_I:
	case TYPE_L:
		/*
		 * isreg is only set if we are not doing restart and we
		 * are sending a regular file
		 */
		netfd = fileno(outstr);
		filefd = fileno(instr);

		if (isreg && filesize < (off_t)16 * 1024 * 1024) {
			buf = mmap(0, filesize, PROT_READ, MAP_SHARED, filefd,
				   (off_t)0);
			if (buf==MAP_FAILED || buf==NULL) {
				syslog(LOG_WARNING, "mmap(%lu): %m",
				       (unsigned long)filesize);
				goto oldway;
			}
			bp = buf;
			len = filesize;
			do {
				cnt = write(netfd, bp, len);
				len -= cnt;
				bp += cnt;
				if (cnt > 0) byte_count += cnt;
			} while(cnt > 0 && len > 0);

			transflag = 0;
			munmap(buf, (size_t)filesize);
			if (cnt < 0)
				goto data_err;
			reply(226, "Transfer complete.");
			return;
		}

oldway:
		if ((buf = malloc((u_int)blksize)) == NULL) {
			transflag = 0;
			perror_reply(451, "Local resource failure: malloc");
			return;
		}

		while ((cnt = read(filefd, buf, (u_int)blksize)) > 0 &&
		    write(netfd, buf, cnt) == cnt)
			byte_count += cnt;
		transflag = 0;
		(void)free(buf);
		if (cnt != 0) {
			if (cnt < 0)
				goto file_err;
			goto data_err;
		}
		reply(226, "Transfer complete.");
		return;
	default:
		transflag = 0;
		reply(550, "Unimplemented TYPE %d in send_data", type);
		return;
	}

data_err:
	transflag = 0;
	perror_reply(426, "Data connection");
	return;

file_err:
	transflag = 0;
	perror_reply(551, "Error on input file");
}

/*
 * Transfer data from peer to "outstr" using the appropriate encapulation of
 * the data subject to Mode, Structure, and Type.
 *
 * N.B.: Form isn't handled.
 */
static int
receive_data(instr, outstr)
	FILE *instr, *outstr;
{
	int c;
	int cnt;
	volatile int bare_lfs = 0;
	char buf[BUFSIZ];

	transflag++;
	if (setjmp(urgcatch)) {
		transflag = 0;
		return (-1);
	}
	switch (type) {

	case TYPE_I:
	case TYPE_L:
		while ((cnt = read(fileno(instr), buf, sizeof(buf))) > 0) {
			if (write(fileno(outstr), buf, cnt) != cnt)
				goto file_err;
			byte_count += cnt;
		}
		if (cnt < 0)
			goto data_err;
		transflag = 0;
		return (0);

	case TYPE_E:
		reply(553, "TYPE E not implemented.");
		transflag = 0;
		return (-1);

	case TYPE_A:
		while ((c = getc(instr)) != EOF) {
			byte_count++;
			if (c == '\n')
				bare_lfs++;
			while (c == '\r') {
				if (ferror(outstr))
					goto data_err;
				if ((c = getc(instr)) != '\n') {
					(void) putc ('\r', outstr);
					if (c == '\0' || c == EOF)
						goto contin2;
				}
			}
			(void) putc(c, outstr);
	contin2:	;
		}
		fflush(outstr);
		if (ferror(instr))
			goto data_err;
		if (ferror(outstr))
			goto file_err;
		transflag = 0;
		if (bare_lfs) {
			lreply(226,
		"WARNING! %d bare linefeeds received in ASCII mode",
			    bare_lfs);
		(void)printf("   File may not have transferred correctly.\r\n");
		}
		return (0);
	default:
		reply(550, "Unimplemented TYPE %d in receive_data", type);
		transflag = 0;
		return (-1);
	}

data_err:
	transflag = 0;
	perror_reply(426, "Data Connection");
	return (-1);

file_err:
	transflag = 0;
	perror_reply(452, "Error writing file");
	return (-1);
}

void
statfilecmd(filename)
	char *filename;
{
	FILE *fin;
	int c;
	char line[LINE_MAX];

	(void)snprintf(line, sizeof(line), "/bin/ls -lgA %s", filename);
	fin = ftpd_popen(line, "r");
	lreply(211, "status of %s:", filename);
	while ((c = getc(fin)) != EOF) {
		if (c == '\n') {
			if (ferror(stdout)){
				perror_reply(421, "control connection");
				(void) ftpd_pclose(fin);
				dologout(1);
				/* NOTREACHED */
			}
			if (ferror(fin)) {
				perror_reply(551, filename);
				(void) ftpd_pclose(fin);
				return;
			}
			(void) putc('\r', stdout);
		}
		(void) putc(c, stdout);
	}
	(void) ftpd_pclose(fin);
	reply(211, "End of Status");
}

void
statcmd()
{
	struct sockaddr_in *sn;
	u_char *a, *p;

	lreply(211, "%s FTP server status:", hostname, version);
	printf("     %s\r\n", version);
	printf("     Connected to %s", remotehost);
	if (!isdigit(remotehost[0]))
		printf(" (%s)", inet_ntoa(his_addr.sin_addr));
	printf("\r\n");
	if (logged_in) {
		if (guest)
			printf("     Logged in anonymously\r\n");
		else
			printf("     Logged in as %s\r\n", pw->pw_name);
	} else if (askpasswd)
		printf("     Waiting for password\r\n");
	else
		printf("     Waiting for user name\r\n");
	printf("     TYPE: %s", typenames[type]);
	if (type == TYPE_A || type == TYPE_E)
		printf(", FORM: %s", formnames[form]);
	if (type == TYPE_L)
#if CHAR_BIT == 8
		printf(" %d", CHAR_BIT);
#else
		printf(" %d", bytesize);	/* need definition! */
#endif
	printf("; STRUcture: %s; transfer MODE: %s\r\n",
	    strunames[stru], modenames[mode]);
	if (data != -1)
		printf("     Data connection open\r\n");
	else if (pdata != -1) {
		printf("     in Passive mode");
		sn = &pasv_addr;
		goto printaddr;
	} else if (usedefault == 0) {
		printf("     PORT");
		sn = &data_dest;
printaddr:
		a = (u_char *) &sn->sin_addr;
		p = (u_char *) &sn->sin_port;
#define UC(b) (((int) b) & 0xff)
		printf(" (%d,%d,%d,%d,%d,%d)\r\n", UC(a[0]),
			UC(a[1]), UC(a[2]), UC(a[3]), UC(p[0]), UC(p[1]));
#undef UC
	} else
		printf("     No data connection\r\n");
	reply(211, "End of status");
}

void
fatal(s)
	const char *s;
{

	reply(451, "Error in server: %s\n", s);
	reply(221, "Closing connection due to server error.");
	dologout(0);
	/* NOTREACHED */
}

void
#if __STDC__
reply(int n, const char *fmt, ...)
#else
reply(n, fmt, va_alist)
	int n;
	char *fmt;
        va_dcl
#endif
{
	va_list ap;
#if __STDC__
	va_start(ap, fmt);
#else
	va_start(ap);
#endif
	(void)printf("%d ", n);
	(void)vprintf(fmt, ap);
	(void)printf("\r\n");
	(void)fflush(stdout);
	if (debug) {
		syslog(LOG_DEBUG, "<--- %d ", n);
		vsyslog(LOG_DEBUG, fmt, ap);
	}
}

void
#if __STDC__
lreply(int n, const char *fmt, ...)
#else
lreply(n, fmt, va_alist)
	int n;
	char *fmt;
        va_dcl
#endif
{
	va_list ap;
#if __STDC__
	va_start(ap, fmt);
#else
	va_start(ap);
#endif
	(void)printf("%d- ", n);
	(void)vprintf(fmt, ap);
	(void)printf("\r\n");
	(void)fflush(stdout);
	if (debug) {
		syslog(LOG_DEBUG, "<--- %d- ", n);
		vsyslog(LOG_DEBUG, fmt, ap);
	}
}

static void
ack(s)
	const char *s;
{

	reply(250, "%s command successful.", s);
}

void
nack(s)
	const char *s;
{

	reply(502, "%s command not implemented.", s);