ftpd.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

/*
 *  chdir
 */
int
cwdcmd(char *dir)
{
	char *rp;
	char buf[Maxpath];

	/* shell cd semantics */
	if(dir == 0 || *dir == 0){
		if(isnone)
			rp = "/";
		else {
			snprint(buf, sizeof buf, "/usr/%s", user);
			rp = buf;
		}
		if(accessok(rp) == 0)
			rp = nil;
	} else
		rp = abspath(dir);

	if(rp == nil)
		return reply("550 Permission denied");

	if(chdir(rp) < 0)
		return reply("550 Cwd failed: %r");
	strcpy(curdir, rp);
	return reply("250 directory changed to %s", curdir);
}

/*
 *  chdir ..
 */
int
cdupcmd(char *dp)
{
	USED(dp);
	return cwdcmd("..");
}

int
quitcmd(char *arg)
{
	USED(arg);
	reply("200 Bye");
	if(pid)
		postnote(PNPROC, pid, "kill");
	return -1;
}

int
typecmd(char *arg)
{
	int c;
	char *x;

	x = arg;
	if(arg == 0)
		return reply("501 Type command needs arguments");

	while(c = *arg++){
		switch(tolower(c)){
		case 'a':
			type = Tascii;
			break;
		case 'i':
		case 'l':
			type = Timage;
			break;
		case '8':
		case ' ':
		case 'n':
		case 't':
		case 'c':
			break;
		default:
			return reply("501 Unimplemented type %s", x);
		}
	}
	return reply("200 Type %s", type==Tascii ? "Ascii" : "Image");
}

int
modecmd(char *arg)
{
	if(arg == 0)
		return reply("501 Mode command needs arguments");
	while(*arg){
		switch(tolower(*arg)){
		case 's':
			mode = Mstream;
			break;
		default:
			return reply("501 Unimplemented mode %c", *arg);
		}
		arg++;
	}
	return reply("200 Stream mode");
}

int
structcmd(char *arg)
{
	if(arg == 0)
		return reply("501 Struct command needs arguments");
	for(; *arg; arg++){
		switch(tolower(*arg)){
		case 'f':
			structure = Sfile;
			break;
		default:
			return reply("501 Unimplemented structure %c", *arg);
		}
	}
	return reply("200 File structure");
}

int
portcmd(char *arg)
{
	char *field[7];
	int n;

	if(arg == 0)
		return reply("501 Port command needs arguments");
	n = getfields(arg, field, 7, 0, ", ");
	if(n != 6)
		return reply("501 Incorrect port specification");
	snprint(data, sizeof data, "tcp!%.3s.%.3s.%.3s.%.3s!%d", field[0], field[1], field[2],
		field[3], atoi(field[4])*256 + atoi(field[5]));
	return reply("200 Data port is %s", data);
}

int
mountnet(void)
{
	int rv;

	rv = 0;

	if(bind("#/", "/", MAFTER) < 0){
		logit("can't bind #/ to /: %r");
		return reply("500 can't bind #/ to /: %r");
	}

	if(bind(nci->spec, "/net", MBEFORE) < 0){
		logit("can't bind %s to /net: %r", nci->spec);
		rv = reply("500 can't bind %s to /net: %r", nci->spec);
		unmount("#/", "/");
	}

	return rv;
}

void
unmountnet(void)
{
	unmount(0, "/net");
	unmount("#/", "/");
}

int
pasvcmd(char *arg)
{
	NetConnInfo *nnci;
	Passive *p;

	USED(arg);
	p = &passive;

	if(p->inuse){
		close(p->afd);
		p->inuse = 0;
	}

	if(mountnet() < 0)
		return 0;

	p->afd = announce("tcp!*!0", passive.adir);
	if(p->afd < 0){
		unmountnet();
		return reply("500 No free ports");
	}
	nnci = getnetconninfo(p->adir, -1);
	unmountnet();

	/* parse the local address */
	if(debug)
		logit("local sys is %s", nci->lsys);
	parseip(p->ipaddr, nci->lsys);
	if(ipcmp(p->ipaddr, v4prefix) == 0 || ipcmp(p->ipaddr, IPnoaddr) == 0)
		parseip(p->ipaddr, nci->lsys);
	p->port = atoi(nnci->lserv);

	freenetconninfo(nnci);
	p->inuse = 1;

	return reply("227 Entering Passive Mode (%d,%d,%d,%d,%d,%d)",
		p->ipaddr[IPv4off+0], p->ipaddr[IPv4off+1], p->ipaddr[IPv4off+2], p->ipaddr[IPv4off+3],
		p->port>>8, p->port&0xff);
}

enum
{
	Narg=32,
};
int Cflag, rflag, tflag, Rflag;
int maxnamelen;
int col;

char*
mode2asc(int m)
{
	static char asc[12];
	char *p;

	strcpy(asc, "----------");
	if(DMDIR & m)
		asc[0] = 'd';
	if(DMAPPEND & m)
		asc[0] = 'a';
	else if(DMEXCL & m)
		asc[3] = 'l';

	for(p = asc+1; p < asc + 10; p += 3, m<<=3){
		if(m & 0400)
			p[0] = 'r';
		if(m & 0200)
			p[1] = 'w';
		if(m & 0100)
			p[2] = 'x';
	}
	return asc;
}
void
listfile(Biobufhdr *b, char *name, int lflag, char *dname)
{
	char ts[32];
	int n, links, pad;
	long now;
	char *x;
	Dir *d;

	x = abspath(name);
	if(x == nil)
		return;
	d = dirstat(x);
	if(d == nil)
		return;
	if(isnone){
		if(strncmp(x, "/incoming/", sizeof("/incoming/")-1) != 0)
			d->mode &= ~0222;
		d->uid = "none";
		d->gid = "none";
	}

	strcpy(ts, ctime(d->mtime));
	ts[16] = 0;
	now = time(0);
	if(now - d->mtime > 6*30*24*60*60)
		memmove(ts+11, ts+23, 5);
	if(lflag){
		/* Unix style long listing */
		if(DMDIR&d->mode){
			links = 2;
			d->length = 512;
		} else
			links = 1;
		
		Bprint(b, "%s %3d %-8s %-8s %7lld %s ",
			mode2asc(d->mode), links,
			d->uid, d->gid, d->length, ts+4);
	}
	if(Cflag && maxnamelen < 40){
		n = strlen(name);
		pad = ((col+maxnamelen)/(maxnamelen+1))*(maxnamelen+1);
		if(pad+maxnamelen+1 < 60){
			Bprint(b, "%*s", pad-col+n, name);
			col = pad+n;
		}
		else{
			Bprint(b, "\r\n%s", name);
			col = n;
		}
	}
	else{
		if(dname)
			Bprint(b, "%s/", dname);
		Bprint(b, "%s\r\n", name);
	}
	free(d);
}
int
dircomp(void *va, void *vb)
{
	int rv;
	Dir *a, *b;

	a = va;
	b = vb;

	if(tflag)
		rv = b->mtime - a->mtime;
	else
		rv = strcmp(a->name, b->name);
	return (rflag?-1:1)*rv;
}
void
listdir(char *name, Biobufhdr *b, int lflag, int *printname, Globlist *gl)
{
	Dir *p;
	int fd, n, i, l;
	char *dname;
	uvlong total;

	col = 0;

	fd = open(name, OREAD);
	if(fd < 0){
		Bprint(b, "can't read %s: %r\r\n", name);
		return;
	}
	dname = 0;
	if(*printname){
		if(Rflag || lflag)
			Bprint(b, "\r\n%s:\r\n", name);
		else
			dname = name;
	}
	n = dirreadall(fd, &p);
	close(fd);
	if(Cflag){
		for(i = 0; i < n; i++){
			l = strlen(p[i].name);
			if(l > maxnamelen)
				maxnamelen = l;
		}
	}

	/* Unix style total line */
	if(lflag){
		total = 0;
		for(i = 0; i < n; i++){
			if(p[i].qid.type & QTDIR)
				total += 512;
			else
				total += p[i].length;
		}
		Bprint(b, "total %ulld\r\n", total/512);
	}
	
	qsort(p, n, sizeof(Dir), dircomp);
	for(i = 0; i < n; i++){
		if(Rflag && (p[i].qid.type & QTDIR)){
			*printname = 1;
			globadd(gl, name, p[i].name);
		}
		listfile(b, p[i].name, lflag, dname);
	}
	free(p);
}
void
list(char *arg, int lflag)
{
	Dir *d;
	Globlist *gl;
	Glob *g;
	int dfd, printname;
	int i, n, argc;
	char *alist[Narg];
	char **argv;
	Biobufhdr bh;
	uchar buf[512];
	char *p, *s;

	if(arg == 0)
		arg = "";

	if(debug)
		logit("ls %s (. = %s)", arg, curdir);

	/* process arguments, understand /bin/ls -l option */
	argv = alist;
	argv[0] = "/bin/ls";
	argc = getfields(arg, argv+1, Narg-2, 1, " \t") + 1;
	argv[argc] = 0;
	rflag = 0;
	tflag = 0;
	Rflag = 0;
	Cflag = 0;
	col = 0;
	ARGBEGIN{
	case 'l':
		lflag++;
		break;
	case 'R':
		Rflag++;
		break;
	case 'C':
		Cflag++;
		break;
	case 'r':
		rflag++;
		break;
	case 't':
		tflag++;
		break;
	}ARGEND;
	if(Cflag)
		lflag = 0;

	dfd = dialdata();
	if(dfd < 0){
		reply("425 Error opening data connection:%r");
		return;
	}
	reply("150 Opened data connection (%s)", data);

	Binits(&bh, dfd, OWRITE, buf, sizeof(buf));
	if(argc == 0){
		argc = 1;
		argv = alist;
		argv[0] = ".";
	}

	for(i = 0; i < argc; i++){
		chdir(curdir);
		gl = glob(argv[i]);
		if(gl == nil)
			continue;
		
		printname = gl->first != nil && gl->first->next != nil;
		maxnamelen = 8;

		if(Cflag)
			for(g = gl->first; g; g = g->next)
				if(g->glob && (n = strlen(s_to_c(g->glob))) > maxnamelen)
					maxnamelen = n;
		while(s = globiter(gl)){
			if(debug)
				logit("glob %s", s);
			p = abspath(s);
			if(p == nil){
				free(s);
				continue;
			}
			d = dirstat(p);
			if(d == nil){
				free(s);
				continue;
			}
			if(d->qid.type & QTDIR)
				listdir(s, &bh, lflag, &printname, gl);
			else
				listfile(&bh, s, lflag, 0);
			free(s);
			free(d);
		}
		globlistfree(gl);
	}
	if(Cflag)
		Bprint(&bh, "\r\n");
	Bflush(&bh);
	close(dfd);

	reply("226 Transfer complete (list %s)", arg);
}
int
namelistcmd(char *arg)
{
	return asproc(list, arg, 0);
}
int
listcmd(char *arg)
{
	return asproc(list, arg, 1);
}

/*
 *  return the size of the file
 */
int
sizecmd(char *arg)
{
	Dir *d;
	int rv;

	if(arg == 0)
		return reply("501 Size command requires pathname");
	arg = abspath(arg);
	d = dirstat(arg);
	if(d == nil)
		return reply("501 %r accessing %s", arg);
	rv = reply("213 %lld", d->length);
	free(d);
	return rv;
}

/*
 *  return the modify time of the file
 */
int
mdtmcmd(char *arg)
{
	Dir *d;
	Tm *t;
	int rv;

	if(arg == 0)
		return reply("501 Mdtm command requires pathname");
	if(arg == 0)
		return reply("550 Permission denied");
	d = dirstat(arg);
	if(d == nil)
		return reply("501 %r accessing %s", arg);
	t = gmtime(d->mtime);
	rv = reply("213 %4.4d%2.2d%2.2d%2.2d%2.2d%2.2d",
			t->year+1900, t->mon+1, t->mday,
			t->hour, t->min, t->sec);
	free(d);
	return rv;
}

/*
 *  set an offset to start reading a file from
 *  only lasts for one command
 */
int
restartcmd(char *arg)
{
	if(arg == 0)
		return reply("501 Restart command requires offset");
	offset = atoll(arg);
	if(offset < 0){
		offset = 0;
		return reply("501 Bad offset");
	}

	return reply("350 Restarting at %lld. Send STORE or RETRIEVE", offset);
}

/*
 *  send a file to the user
 */
int
crlfwrite(int fd, char *p, int n)
{
	char *ep, *np;
	char buf[2*Nbuf];

	for(np = buf, ep = p + n; p < ep; p++){
		if(*p == '\n')
			*np++ = '\r';
		*np++ = *p;
	}
	if(write(fd, buf, np - buf) == np - buf)
		return n;
	else
		return -1;
}
void
retrievedir(char *arg)
{
	int n;
	char *p;
	String *file;

	if(type != Timage){
		reply("550 This file requires type binary/image");
		return;
	}

	file = s_copy(arg);
	p = strrchr(s_to_c(file), '/');
	if(p != s_to_c(file)){
		*p++ = 0;
		chdir(s_to_c(file));
	} else {
		chdir("/");
		p = s_to_c(file)+1;
	}

	n = transfer("/bin/tar", "c", p, 0, 1);
	if(n < 0)
		logit("get %s failed", arg);
	else
		logit("get %s OK %d", arg, n);
	s_free(file);
}
void
retrieve(char *arg, int arg2)
{
	int dfd, fd, n, i, bytes;
	Dir *d;
	char buf[Nbuf];
	char *p, *ep;

	USED(arg2);

	p = strchr(arg, '\r');
	if(p){
		logit("cr in file name", arg);
		*p = 0;
	}

	fd = open(arg, OREAD);
	if(fd == -1){
		n = strlen(arg);
		if(n > 4 && strcmp(arg+n-4, ".tar") == 0){