hget.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

			tm.year--;
	}

	strcpy(tm.zone, "GMT");
	/* convert to epoch seconds */
	u->mtime = tm2sec(&tm);
}

void
hhclen(char *p, URL*, Range *r)
{
	r->end = atoi(p);
}

void
hhcrange(char *p, URL*, Range *r)
{
	char *x;
	vlong l;

	l = 0;
	x = strchr(p, '/');
	if(x)
		l = atoll(x+1);
	if(l == 0) {
		x = strchr(p, '-');
		if(x)
			l = atoll(x+1);
	}
	if(l)
		r->end = l;
}

void
hhuri(char *p, URL *u, Range*)
{
	if(*p != '<')
		return;
	u->redirect = strdup(p+1);
	p = strchr(u->redirect, '>');
	if(p != nil)
		*p = 0;
}

void
hhlocation(char *p, URL *u, Range*)
{
	u->redirect = strdup(p);
}

void
hhauth(char *p, URL *u, Range*)
{
	char *f[4];
	UserPasswd *up;
	char *s, cred[64];

	if (cistrncmp(p, "basic ", 6) != 0)
		sysfatal("only Basic authentication supported");

	if (gettokens(p, f, nelem(f), "\"") < 2)
		sysfatal("garbled auth data");

	if ((up = auth_getuserpasswd(auth_getkey, "proto=pass service=http server=%q realm=%q",
	    	u->host, f[1])) == nil)
			sysfatal("cannot authenticate");

	s = smprint("%s:%s", up->user, up->passwd);
	if(enc64(cred, sizeof(cred), (uchar *)s, strlen(s)) == -1)
		sysfatal("enc64");
  		free(s);

	assert(u->cred = strdup(cred));
}

enum
{
	/* ftp return codes */
	Extra=		1,
	Success=	2,
	Incomplete=	3,
	TempFail=	4,
	PermFail=	5,

	Nnetdir=	64,	/* max length of network directory paths */
	Ndialstr=	64,		/* max length of dial strings */
};

int ftpcmd(int, char*, ...);
int ftprcode(int, char*, int);
int hello(int);
int logon(int);
int xfertype(int, char*);
int passive(int, URL*);
int active(int, URL*);
int ftpxfer(int, Out*, Range*);
int terminateftp(int, int);
int getaddrport(char*, uchar*, uchar*);
int ftprestart(int, Out*, URL*, Range*, long);

int
doftp(URL *u, URL *px, Range *r, Out *out, long mtime)
{
	int pid, ctl, data, rv;
	Waitmsg *w;
	char msg[64];
	char conndir[NETPATHLEN];
	char *p;

	/* untested, proxy doesn't work with ftp (I think) */
	if(px->host == nil){
		ctl = dial(netmkaddr(u->host, tcpdir, u->port), 0, conndir, 0);
	} else {
		ctl = dial(netmkaddr(px->host, tcpdir, px->port), 0, conndir, 0);
	}

	if(ctl < 0)
		return Error;
	if(net == nil){
		p = strrchr(conndir, '/');
		*p = 0;
		snprint(tcpdir, sizeof(tcpdir), conndir);
	}

	initibuf();

	rv = hello(ctl);
	if(rv < 0)
		return terminateftp(ctl, rv);

	rv = logon(ctl);
	if(rv < 0)
		return terminateftp(ctl, rv);

	rv = xfertype(ctl, "I");
	if(rv < 0)
		return terminateftp(ctl, rv);

	/* if file is up to date and the right size, stop */
	if(ftprestart(ctl, out, u, r, mtime) > 0){
		close(ctl);
		return Eof;
	}
		
	/* first try passive mode, then active */
	data = passive(ctl, u);
	if(data < 0){
		data = active(ctl, u);
		if(data < 0)
			return Error;
	}

	/* fork */
	switch(pid = rfork(RFPROC|RFFDG|RFMEM)){
	case -1:
		close(data);
		return terminateftp(ctl, Error);
	case 0:
		ftpxfer(data, out, r);
		close(data);
		_exits(0);
	default:
		close(data);
		break;
	}

	/* wait for reply message */
	rv = ftprcode(ctl, msg, sizeof(msg));
	close(ctl);

	/* wait for process to terminate */
	w = nil;
	for(;;){
		free(w);
		w = wait();
		if(w == nil)
			return Error;
		if(w->pid == pid){
			if(w->msg[0] == 0){
				free(w);
				break;
			}
			werrstr("xfer: %s", w->msg);
			free(w);
			return Error;
		}
	}

	switch(rv){
	case Success:
		return Eof;
	case TempFail:
		return Server;
	default:
		return Error;
	}
}

int
ftpcmd(int ctl, char *fmt, ...)
{
	va_list arg;
	char buf[2*1024], *s;

	va_start(arg, fmt);
	s = vseprint(buf, buf + (sizeof(buf)-4) / sizeof(*buf), fmt, arg);
	va_end(arg);
	if(debug)
		fprint(2, "%d -> %s\n", ctl, buf);
	*s++ = '\r';
	*s++ = '\n';
	if(write(ctl, buf, s - buf) != s - buf)
		return -1;
	return 0;
}

int
ftprcode(int ctl, char *msg, int len)
{
	int rv;
	int i;
	char *p;

	len--;	/* room for terminating null */
	for(;;){
		*msg = 0;
		i = readline(ctl, msg, len);
		if(i < 0)
			break;
		if(debug)
			fprint(2, "%d <- %s\n", ctl, msg);

		/* stop if not a continuation */
		rv = strtol(msg, &p, 10);
		if(rv >= 100 && rv < 600 && p==msg+3 && *p == ' ')
			return rv/100;
	}
	*msg = 0;

	return -1;
}

int
hello(int ctl)
{
	char msg[1024];

	/* wait for hello from other side */
	if(ftprcode(ctl, msg, sizeof(msg)) != Success){
		werrstr("HELLO: %s", msg);
		return Server;
	}
	return 0;
}

int
getdec(char *p, int n)
{
	int x = 0;
	int i;

	for(i = 0; i < n; i++)
		x = x*10 + (*p++ - '0');
	return x;
}

int
ftprestart(int ctl, Out *out, URL *u, Range *r, long mtime)
{
	Tm tm;
	char msg[1024];
	long x, rmtime;

	ftpcmd(ctl, "MDTM %s", u->page);
	if(ftprcode(ctl, msg, sizeof(msg)) != Success){
		r->start = 0;
		return 0;		/* need to do something */
	}

	/* decode modification time */
	if(strlen(msg) < 4 + 4 + 2 + 2 + 2 + 2 + 2){
		r->start = 0;
		return 0;		/* need to do something */
	}
	memset(&tm, 0, sizeof(tm));
	tm.year = getdec(msg+4, 4) - 1900;
	tm.mon = getdec(msg+4+4, 2) - 1;
	tm.mday = getdec(msg+4+4+2, 2);
	tm.hour = getdec(msg+4+4+2+2, 2);
	tm.min = getdec(msg+4+4+2+2+2, 2);
	tm.sec = getdec(msg+4+4+2+2+2+2, 2);
	strcpy(tm.zone, "GMT");
	rmtime = tm2sec(&tm);
	if(rmtime > mtime)
		r->start = 0;

	/* get size */
	ftpcmd(ctl, "SIZE %s", u->page);
	if(ftprcode(ctl, msg, sizeof(msg)) == Success){
		x = atol(msg+4);
		if(r->start == x)
			return 1;	/* we're up to date */
		r->end = x;
	}

	/* seek to restart point */
	if(r->start > 0){
		ftpcmd(ctl, "REST %lud", r->start);
		if(ftprcode(ctl, msg, sizeof(msg)) == Incomplete){
			setoffset(out, r->start);
		}else
			r->start = 0;
	}

	return 0;	/* need to do something */
}

int
logon(int ctl)
{
	char msg[1024];

	/* login anonymous */
	ftpcmd(ctl, "USER anonymous");
	switch(ftprcode(ctl, msg, sizeof(msg))){
	case Success:
		return 0;
	case Incomplete:
		break;	/* need password */
	default:
		werrstr("USER: %s", msg);
		return Server;
	}

	/* send user id as password */
	sprint(msg, "[e-mail]", getuser());
	ftpcmd(ctl, "PASS %s", msg);
	if(ftprcode(ctl, msg, sizeof(msg)) != Success){
		werrstr("PASS: %s", msg);
		return Server;
	}

	return 0;
}

int
xfertype(int ctl, char *t)
{
	char msg[1024];

	ftpcmd(ctl, "TYPE %s", t);
	if(ftprcode(ctl, msg, sizeof(msg)) != Success){
		werrstr("TYPE %s: %s", t, msg);
		return Server;
	}

	return 0;
}

int
passive(int ctl, URL *u)
{
	char msg[1024];
	char ipaddr[32];
	char *f[6];
	char *p;
	int fd;
	int port;
	char aport[12];

	ftpcmd(ctl, "PASV");
	if(ftprcode(ctl, msg, sizeof(msg)) != Success)
		return Error;

	/* get address and port number from reply, this is AI */
	p = strchr(msg, '(');
	if(p == nil){
		for(p = msg+3; *p; p++)
			if(isdigit(*p))
				break;
	} else
		p++;
	if(getfields(p, f, 6, 0, ",)") < 6){
		werrstr("ftp protocol botch");
		return Server;
	}
	snprint(ipaddr, sizeof(ipaddr), "%s.%s.%s.%s",
		f[0], f[1], f[2], f[3]);
	port = ((atoi(f[4])&0xff)<<8) + (atoi(f[5])&0xff);
	sprint(aport, "%d", port);

	/* open data connection */
	fd = dial(netmkaddr(ipaddr, tcpdir, aport), 0, 0, 0);
	if(fd < 0){
		werrstr("passive mode failed: %r");
		return Error;
	}

	/* tell remote to send a file */
	ftpcmd(ctl, "RETR %s", u->page);
	if(ftprcode(ctl, msg, sizeof(msg)) != Extra){
		werrstr("RETR %s: %s", u->page, msg);
		return Error;
	}
	return fd;
}

int
active(int ctl, URL *u)
{
	char msg[1024];
	char dir[40], ldir[40];
	uchar ipaddr[4];
	uchar port[2];
	int lcfd, dfd, afd;

	/* announce a port for the call back */
	snprint(msg, sizeof(msg), "%s!*!0", tcpdir);
	afd = announce(msg, dir);
	if(afd < 0)
		return Error;

	/* get a local address/port of the annoucement */
	if(getaddrport(dir, ipaddr, port) < 0){
		close(afd);
		return Error;
	}

	/* tell remote side address and port*/
	ftpcmd(ctl, "PORT %d,%d,%d,%d,%d,%d", ipaddr[0], ipaddr[1], ipaddr[2],
		ipaddr[3], port[0], port[1]);
	if(ftprcode(ctl, msg, sizeof(msg)) != Success){
		close(afd);
		werrstr("active: %s", msg);
		return Error;
	}

	/* tell remote to send a file */
	ftpcmd(ctl, "RETR %s", u->page);
	if(ftprcode(ctl, msg, sizeof(msg)) != Extra){
		close(afd);
		werrstr("RETR: %s", msg);
		return Server;
	}

	/* wait for a connection */
	lcfd = listen(dir, ldir);
	if(lcfd < 0){
		close(afd);
		return Error;
	}
	dfd = accept(lcfd, ldir);
	if(dfd < 0){
		close(afd);
		close(lcfd);
		return Error;
	}
	close(afd);
	close(lcfd);
	
	return dfd;
}

int
ftpxfer(int in, Out *out, Range *r)
{
	char buf[1024];
	long vtime;
	int i, n;

	vtime = 0;
	for(n = 0;;n += i){
		i = read(in, buf, sizeof(buf));
		if(i == 0)
			break;
		if(i < 0)
			return Error;
		if(output(out, buf, i) != i)
			return Error;
		r->start += i;
		if(verbose && (vtime != time(0) || r->start == r->end)) {
			vtime = time(0);
			fprint(2, "%ld %ld\n", r->start, r->end);
		}
	}
	return n;
}

int
terminateftp(int ctl, int rv)
{
	close(ctl);
	return rv;
}

/*
 * case insensitive strcmp (why aren't these in libc?)
 */
int
cistrncmp(char *a, char *b, int n)
{
	while(n-- > 0){
		if(tolower(*a++) != tolower(*b++))
			return -1;
	}
	return 0;
}

int
cistrcmp(char *a, char *b)
{
	while(*a || *b)
		if(tolower(*a++) != tolower(*b++))
			return -1;

	return 0;
}

/*
 *  buffered io
 */
struct
{
	char *rp;
	char *wp;
	char buf[4*1024];
} b;

void
initibuf(void)
{
	b.rp = b.wp = b.buf;
}

/*
 *  read a possibly buffered line, strip off trailing while
 */
int
readline(int fd, char *buf, int len)
{
	int n;
	char *p;
	int eof = 0;

	len--;

	for(p = buf;;){
		if(b.rp >= b.wp){
			n = read(fd, b.wp, sizeof(b.buf)/2);
			if(n < 0)
				return -1;
			if(n == 0){
				eof = 1;
				break;
			}
			b.wp += n;
		}
		n = *b.rp++;
		if(len > 0){
			*p++ = n;
			len--;
		}
		if(n == '\n')
			break;
	}

	/* drop trailing white */
	for(;;){
		if(p <= buf)
			break;
		n = *(p-1);
		if(n != ' ' && n != '\t' && n != '\r' && n != '\n')
			break;
		p--;
	}
	*p = 0;

	if(eof && p == buf)
		return -1;

	return p-buf;
}

void
unreadline(char *line)
{
	int i, n;

	i = strlen(line);
	n = b.wp-b.rp;
	memmove(&b.buf[i+1], b.rp, n);
	memmove(b.buf, line, i);
	b.buf[i] = '\n';
	b.rp = b.buf;
	b.wp = b.rp + i + 1 + n;
}

int
readibuf(int fd, char *buf, int len)
{
	int n;

	n = b.wp-b.rp;
	if(n > 0){
		if(n > len)
			n = len;
		memmove(buf, b.rp, n);
		b.rp += n;
		return n;
	}
	return read(fd, buf, len);
}

int
dfprint(int fd, char *fmt, ...)
{
	char buf[4*1024];
	va_list arg;

	va_start(arg, fmt);
	vseprint(buf, buf+sizeof(buf), fmt, arg);
	va_end(arg);
	if(debug)
		fprint(2, "%d -> %s", fd, buf);
	return fprint(fd, "%s", buf);
}

int
getaddrport(char *dir, uchar *ipaddr, uchar *port)
{
	char buf[256];
	int fd, i;
	char *p;

	snprint(buf, sizeof(buf), "%s/local", dir);
	fd = open(buf, OREAD);
	if(fd < 0)
		return -1;
	i = read(fd, buf, sizeof(buf)-1);
	close(fd);
	if(i <= 0)
		return -1;
	buf[i] = 0;
	p = strchr(buf, '!');
	if(p != nil)
		*p++ = 0;
	v4parseip(ipaddr, buf);
	i = atoi(p);
	port[0] = i>>8;
	port[1] = i;
	return 0;
}

void
md5free(DigestState *state)
{
	uchar x[MD5dlen];
	md5(nil, 0, x, state);
}

DigestState*
md5dup(DigestState *state)
{
	char *p;

	p = md5pickle(state);
	if(p == nil)
		sysfatal("md5pickle: %r");
	state = md5unpickle(p);
	if(state == nil)
		sysfatal("md5unpickle: %r");
	free(p);
	return state;
}

void
setoffset(Out *out, int offset)
{
	md5free(out->curr);
	if(offset == 0)
		out->curr = md5(nil, 0, nil, nil);
	else
		out->curr = nil;
	out->offset = offset;
	out->written = offset;
	if(ofile != nil)
		if(seek(out->fd, offset, 0) != offset)
			sysfatal("seek: %r");
}

/*
 * write some output, discarding it (but keeping track)
 * if we've already written it. if we've gone backwards,
 * verify that everything previously written matches
 * that which would have been written from the current
 * output.
 */
int
output(Out *out, char *buf, int nb)
{
	int n, d;
	uchar m0[MD5dlen], m1[MD5dlen];

	n = nb;
	d = out->written - out->offset;
	assert(d >= 0);
	if(d > 0){
		if(n < d){
			if(out->curr != nil)
				md5((uchar*)buf, n, nil, out->curr);
			out->offset += n;
			return n;
		}
		if(out->curr != nil){
			md5((uchar*)buf, d, m0, out->curr);
			out->curr = nil;
			md5(nil, 0, m1, md5dup(out->hiwat));
			if(memcmp(m0, m1, MD5dlen) != 0){
				fprint(2, "integrity check failure at offset %d\n", out->written);
				return -1;
			}
		}
		buf += d;
		n -= d;
		out->offset += d;
	}
	if(n > 0){
		out->hiwat = md5((uchar*)buf, n, nil, out->hiwat);
		n = write(out->fd, buf, n);
		if(n > 0){
			out->offset += n;
			out->written += n;
		}
	}
	return n + d;
}