xref: /plan9/sys/src/cmd/webfs/cookies.c (revision 2c23bbf7b5b71c88de0d92a1b1ea4a1a9e240601)

#include <u.h>
#include <libc.h>
#include <bio.h>
#include <ndb.h>
#include <fcall.h>
#include <thread.h>
#include <9p.h>
#include <ctype.h>
#include "dat.h"
#include "fns.h"

int cookiedebug;

typedef struct Cookie Cookie;
typedef struct Jar Jar;

struct Cookie
{
	/* external info */
	char*	name;
	char*	value;
	char*	dom;		/* starts with . */
	char*	path;
	char*	version;
	char*	comment;		/* optional, may be nil */

	uint		expire;		/* time of expiration: ~0 means when webcookies dies */
	int		secure;
	int		explicitdom;	/* dom was explicitly set */
	int		explicitpath;	/* path was explicitly set */
	int		netscapestyle;

	/* internal info */
	int		deleted;
	int		mark;
	int		ondisk;
};

struct Jar
{
	Cookie	*c;
	int		nc;
	int		mc;

	Qid		qid;
	int		dirty;
	char		*file;
	char		*lockfile;
};

struct {
	char *s;
	int	offset;
	int	ishttp;
} stab[] = {
	"domain",		offsetof(Cookie, dom),		1,
	"path",		offsetof(Cookie, path),		1,
	"name",		offsetof(Cookie, name),		0,
	"value",		offsetof(Cookie, value),		0,
	"comment",	offsetof(Cookie, comment),	1,
	"version",		offsetof(Cookie, version),		1,
};

struct {
	char *s;
	int	offset;
} itab[] = {
	"expire",			offsetof(Cookie, expire),
	"secure",			offsetof(Cookie, secure),
	"explicitdomain",	offsetof(Cookie, explicitdom),
	"explicitpath",		offsetof(Cookie, explicitpath),
	"netscapestyle",	offsetof(Cookie, netscapestyle),
};

#pragma varargck type "J"	Jar*
#pragma varargck type "K"	Cookie*

/* HTTP format */
static int
jarfmt(Fmt *fp)
{
	int i;
	Jar *jar;

	jar = va_arg(fp->args, Jar*);

	if(jar == nil || jar->nc == 0)
		return 0;

	fmtstrcpy(fp, "Cookie: ");
	if(jar->c[0].version)
		fmtprint(fp, "$Version=%s; ", jar->c[0].version);
	for(i=0; i<jar->nc; i++)
		fmtprint(fp, "%s%s=%s", i ? "; ": "", jar->c[i].name, jar->c[i].value);
	fmtstrcpy(fp, "\r\n");
	return 0;
}

/* individual cookie */
static int
cookiefmt(Fmt *fp)
{
	int j, k, first;
	char *t;
	Cookie *c;

	c = va_arg(fp->args, Cookie*);

	first = 1;
	for(j=0; j<nelem(stab); j++){
		t = *(char**)((uintptr)c+stab[j].offset);
		if(t == nil)
			continue;
		if(first)
			first = 0;
		else
			fmtstrcpy(fp, " ");
		fmtprint(fp, "%s=%q", stab[j].s, t);
	}
	for(j=0; j<nelem(itab); j++){
		k = *(int*)((uintptr)c+itab[j].offset);
		if(k == 0)
			continue;
		if(first)
			first = 0;
		else
			fmtstrcpy(fp, " ");
		fmtprint(fp, "%s=%ud", itab[j].s, k);
	}
	return 0;
}

/*
 * sort cookies:
 *	- alpha by name
 *	- alpha by domain
 *	- longer paths first, then alpha by path (RFC2109 4.3.4)
 */
static int
cookiecmp(Cookie *a, Cookie *b)
{
	int i;

	if((i = strcmp(a->name, b->name)) != 0)
		return i;
	if((i = cistrcmp(a->dom, b->dom)) != 0)
		return i;
	if((i = strlen(b->path) - strlen(a->path)) != 0)
		return i;
	if((i = strcmp(a->path, b->path)) != 0)
		return i;
	return 0;
}

static int
exactcookiecmp(Cookie *a, Cookie *b)
{
	int i;

	if((i = cookiecmp(a, b)) != 0)
		return i;
	if((i = strcmp(a->value, b->value)) != 0)
		return i;
	if(a->version || b->version){
		if(!a->version)
			return -1;
		if(!b->version)
			return 1;
		if((i = strcmp(a->version, b->version)) != 0)
			return i;
	}
	if(a->comment || b->comment){
		if(!a->comment)
			return -1;
		if(!b->comment)
			return 1;
		if((i = strcmp(a->comment, b->comment)) != 0)
			return i;
	}
	if((i = b->expire - a->expire) != 0)
		return i;
	if((i = b->secure - a->secure) != 0)
		return i;
	if((i = b->explicitdom - a->explicitdom) != 0)
		return i;
	if((i = b->explicitpath - a->explicitpath) != 0)
		return i;
	if((i = b->netscapestyle - a->netscapestyle) != 0)
		return i;

	return 0;
}

static void
freecookie(Cookie *c)
{
	int i;

	for(i=0; i<nelem(stab); i++)
		free(*(char**)((uintptr)c+stab[i].offset));
}

static void
copycookie(Cookie *c)
{
	int i;
	char **ps;

	for(i=0; i<nelem(stab); i++){
		ps = (char**)((uintptr)c+stab[i].offset);
		if(*ps)
			*ps = estrdup9p(*ps);
	}
}

static void
delcookie(Jar *j, Cookie *c)
{
	int i;

	j->dirty = 1;
	i = c - j->c;
	if(i < 0 || i >= j->nc)
		abort();
	c->deleted = 1;
}

static void
addcookie(Jar *j, Cookie *c)
{
	int i;

	if(!c->name || !c->value || !c->path || !c->dom){
		fprint(2, "not adding incomplete cookie\n");
		return;
	}

	if(cookiedebug)
		fprint(2, "add %K\n", c);

	for(i=0; i<j->nc; i++)
		if(cookiecmp(&j->c[i], c) == 0){
			if(cookiedebug)
				fprint(2, "cookie %K matches %K\n", &j->c[i], c);
			if(exactcookiecmp(&j->c[i], c) == 0){
				if(cookiedebug)
					fprint(2, "\texactly\n");
				j->c[i].mark = 0;
				return;
			}
			delcookie(j, &j->c[i]);
		}

	j->dirty = 1;
	if(j->nc == j->mc){
		j->mc += 16;
		j->c = erealloc9p(j->c, j->mc*sizeof(Cookie));
	}
	j->c[j->nc] = *c;
	copycookie(&j->c[j->nc]);
	j->nc++;
}

static void
purgejar(Jar *j)
{
	int i;

	for(i=j->nc-1; i>=0; i--){
		if(!j->c[i].deleted)
			continue;
		freecookie(&j->c[i]);
		--j->nc;
		j->c[i] = j->c[j->nc];
	}
}

static void
addtojar(Jar *jar, char *line, int ondisk)
{
	Cookie c;
	int i, j, nf, *pint;
	char *f[20], *attr, *val, **pstr;

	memset(&c, 0, sizeof c);
	c.expire = ~0;
	c.ondisk = ondisk;
	nf = tokenize(line, f, nelem(f));
	for(i=0; i<nf; i++){
		attr = f[i];
		if((val = strchr(attr, '=')) != nil)
			*val++ = '\0';
		else
			val = "";
		/* string attributes */
		for(j=0; j<nelem(stab); j++){
			if(strcmp(stab[j].s, attr) == 0){
				pstr = (char**)((uintptr)&c+stab[j].offset);
				*pstr = val;
			}
		}
		/* integer attributes */
		for(j=0; j<nelem(itab); j++){
			if(strcmp(itab[j].s, attr) == 0){
				pint = (int*)((uintptr)&c+itab[j].offset);
				if(val[0]=='\0')
					*pint = 1;
				else
					*pint = strtoul(val, 0, 0);
			}
		}
	}
	if(c.name==nil || c.value==nil || c.dom==nil || c.path==nil){
		if(cookiedebug)
			fprint(2, "ignoring fractional cookie %K\n", &c);
		return;
	}
	addcookie(jar, &c);
}

static Jar*
newjar(void)
{
	Jar *jar;

	jar = emalloc9p(sizeof(Jar));
	return jar;
}

static int
expirejar(Jar *jar, int exiting)
{
	int i, n;
	uint now;

	now = time(0);
	n = 0;
	for(i=0; i<jar->nc; i++){
		if(jar->c[i].expire < now || (exiting && jar->c[i].expire==~0)){
			delcookie(jar, &jar->c[i]);
			n++;
		}
	}
	return n;
}

static void
dumpjar(Jar *jar, char *desc)
{
	int i;
	Biobuf *b;
	char *s;

	print("%s\n", desc);
	print("\tin memory:\n");

	for(i=0; i<jar->nc; i++)
		print("\t%K%s%s%s\n", &jar->c[i],
			jar->c[i].ondisk ? " ondisk" : "",
			jar->c[i].deleted ? " deleted" : "",
			jar->c[i].mark ? " mark" : "");
	print("\n\ton disk:\n");
	if((b = Bopen(jar->file, OREAD)) == nil){
		print("\tno file\n");
	}else{
		while((s = Brdstr(b, '\n', 1)) != nil){
			print("\t%s\n", s);
			free(s);
		}
		Bterm(b);
	}
	print("\n");
}

static int
syncjar(Jar *jar)
{
	int i, fd;
	char *line;
	Dir *d;
	Biobuf *b;
	Qid q;

	if(jar->file==nil)
		return 0;

	memset(&q, 0, sizeof q);
	if((d = dirstat(jar->file)) != nil){
		q = d->qid;
		if(d->qid.path != jar->qid.path || d->qid.vers != jar->qid.vers)
			jar->dirty = 1;
		free(d);
	}

	if(jar->dirty == 0)
		return 0;

	fd = -1;
	for(i=0; i<50; i++){
		if((fd = create(jar->lockfile, OWRITE, DMEXCL|0666)) < 0){
			sleep(100);
			continue;
		}
		break;
	}
	if(fd < 0){
		if(cookiedebug)
			fprint(2, "open %s: %r", jar->lockfile);
		werrstr("cannot acquire jar lock: %r");
		return -1;
	}

	for(i=0; i<jar->nc; i++)	/* mark is cleared by addcookie */
		jar->c[i].mark = jar->c[i].ondisk;

	if((b = Bopen(jar->file, OREAD)) == nil){
		if(cookiedebug)
			fprint(2, "Bopen %s: %r", jar->file);
		werrstr("cannot read cookie file %s: %r", jar->file);
		close(fd);
		return -1;
	}
	for(; (line = Brdstr(b, '\n', 1)) != nil; free(line)){
		if(*line == '#')
			continue;
		addtojar(jar, line, 1);
	}
	Bterm(b);

	for(i=0; i<jar->nc; i++)
		if(jar->c[i].mark && jar->c[i].expire != ~0)
			delcookie(jar, &jar->c[i]);

	purgejar(jar);

	b = Bopen(jar->file, OWRITE);
	if(b == nil){
		if(cookiedebug)
			fprint(2, "Bopen write %s: %r", jar->file);
		close(fd);
		return -1;
	}
	Bprint(b, "# webcookies cookie jar\n");
	Bprint(b, "# comments and non-standard fields will be lost\n");
	for(i=0; i<jar->nc; i++){
		if(jar->c[i].expire == ~0)
			continue;
		Bprint(b, "%K\n", &jar->c[i]);
		jar->c[i].ondisk = 1;
	}
	Bterm(b);

	jar->dirty = 0;
	close(fd);
	if((d = dirstat(jar->file)) != nil){
		jar->qid = d->qid;
		free(d);
	}
	return 0;
}

static Jar*
readjar(char *file)
{
	char *lock, *p;
	Jar *jar;

	jar = newjar();
	lock = emalloc9p(strlen(file)+10);
	strcpy(lock, file);
	if((p = strrchr(lock, '/')) != nil)
		p++;
	else
		p = lock;
	memmove(p+2, p, strlen(p)+1);
	p[0] = 'L';
	p[1] = '.';
	jar->lockfile = lock;
	jar->file = file;
	jar->dirty = 1;

	if(syncjar(jar) < 0){
		free(jar->file);
		free(jar->lockfile);
		free(jar);
		return nil;
	}
	return jar;
}

static void
closejar(Jar *jar)
{
	int i;

	if(jar == nil)
		return;
	expirejar(jar, 0);
	if(syncjar(jar) < 0)
		fprint(2, "warning: cannot rewrite cookie jar: %r\n");

	for(i=0; i<jar->nc; i++)
		freecookie(&jar->c[i]);

	free(jar->file);
	free(jar);
}

/*
 * Domain name matching is per RFC2109, section 2:
 *
 * Hosts names can be specified either as an IP address or a FQHN
 * string.  Sometimes we compare one host name with another.  Host A's
 * name domain-matches host B's if
 *
 * * both host names are IP addresses and their host name strings match
 *   exactly; or
 *
 * * both host names are FQDN strings and their host name strings match
 *   exactly; or
 *
 * * A is a FQDN string and has the form NB, where N is a non-empty name
 *   string, B has the form .B', and B' is a FQDN string.  (So, x.y.com
 *   domain-matches .y.com but not y.com.)
 *
 * Note that domain-match is not a commutative operation: a.b.c.com
 * domain-matches .c.com, but not the reverse.
 *
 * (This does not verify that IP addresses and FQDN's are well-formed.)
 */
static int
isdomainmatch(char *name, char *pattern)
{
	int lname, lpattern;

	if(cistrcmp(name, pattern)==0)
		return 1;

	if(strcmp(ipattr(name), "dom")==0 && pattern[0]=='.'){
		lname = strlen(name);
		lpattern = strlen(pattern);
		/* e.g., name: www.google.com && pattern: .google.com */
		if(lname >= lpattern && cistrcmp(name+lname-lpattern, pattern)==0)
			return 1;
		/* e.g., name: google.com && pattern: .google.com */
		if(lpattern > lname &&
		    cistrcmp(pattern+lpattern-lname, name) == 0)
			return 1;
	}
	return 0;
}

/*
 * RFC2109 4.3.4:
 *	- domain must match
 *	- path in cookie must be a prefix of request path
 *	- cookie must not have expired
 */
static int
iscookiematch(Cookie *c, char *dom, char *path, uint now)
{
	return isdomainmatch(dom, c->dom)
		&& strncmp(c->path, path, strlen(c->path))==0
		&& (c->expire == 0 || c->expire >= now);
}

/*
 * Produce a subjar of matching cookies.
 * Secure cookies are only included if secure is set.
 */
static Jar*
cookiesearch(Jar *jar, char *dom, char *path, int issecure)
{
	int i;
	Jar *j;
	uint now;

	if(cookiedebug)
		fprint(2, "cookiesearch %s %s %d\n", dom, path, issecure);
	now = time(0);
	j = newjar();
	for(i=0; i<jar->nc; i++){
		if(cookiedebug)
			fprint(2, "\ttry %s %s %d %s\n", jar->c[i].dom,
				jar->c[i].path, jar->c[i].secure,
				jar->c[i].name);
		if((issecure || !jar->c[i].secure) &&
		    iscookiematch(&jar->c[i], dom, path, now)){
			if(cookiedebug)
				fprint(2, "\tmatched\n");
			addcookie(j, &jar->c[i]);
		}
	}
	if(j->nc == 0){
		closejar(j);
		werrstr("no cookies found");
		return nil;
	}
	qsort(j->c, j->nc, sizeof(j->c[0]), (int(*)(void*, void*))cookiecmp);
	return j;
}

/*
 * RFC2109 4.3.2 security checks
 */
static char*
isbadcookie(Cookie *c, char *dom, char *path)
{
	int lcdom, ldom;

	if(strncmp(c->path, path, strlen(c->path)) != 0)
		return "cookie path is not a prefix of the request path";

	/*
	 * fgb says omitting this test is necessary to get some sites to work,
	 * but it seems dubious.
	 */
	if(c->explicitdom && c->dom[0] != '.')
		return "cookie domain doesn't start with dot";

	lcdom = strlen(c->dom);
	if(memchr(c->dom+1, '.', lcdom-1-1) == nil)
		return "cookie domain doesn't have embedded dots";

	if(!isdomainmatch(dom, c->dom))
		return "request host does not match cookie domain";

	ldom = strlen(dom);
	if(strcmp(ipattr(dom), "dom")==0 && lcdom > ldom &&
	    memchr(dom, '.', lcdom - ldom) != nil)
		return "request host contains dots before cookie domain";

	return 0;
}

/*
 * Sunday, 25-Jan-2002 12:24:36 GMT
 * Sunday, 25 Jan 2002 12:24:36 GMT
 * Sun, 25 Jan 02 12:24:36 GMT
 */
static int
isleap(int year)
{
	return year%4==0 && (year%100!=0 || year%400==0);
}

static uint
strtotime(char *s)
{
	char *os;
	int i;
	Tm tm;

	static int mday[2][12] = {
		31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31,
		31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31,
	};
	static char *wday[] = {
		"Sunday", "Monday", "Tuesday", "Wednesday",
		"Thursday", "Friday", "Saturday",
	};
	static char *mon[] = {
		"Jan", "Feb", "Mar", "Apr", "May", "Jun",
		"Jul", "Aug", "Sep", "Oct", "Nov", "Dec",
	};

	os = s;
	/* Sunday, */
	for(i=0; i<nelem(wday); i++){
		if(cistrncmp(s, wday[i], strlen(wday[i])) == 0){
			s += strlen(wday[i]);
			break;
		}
		if(cistrncmp(s, wday[i], 3) == 0){
			s += 3;
			break;
		}
	}
	if(i==nelem(wday)){
		if(cookiedebug)
			fprint(2, "bad wday (%s)\n", os);
		return -1;
	}
	if(*s++ != ',' || *s++ != ' '){
		if(cookiedebug)
			fprint(2, "bad wday separator (%s)\n", os);
		return -1;
	}

	/* 25- */
	if(!isdigit(s[0]) || !isdigit(s[1]) || (s[2]!='-' && s[2]!=' ')){
		if(cookiedebug)
			fprint(2, "bad day of month (%s)\n", os);
		return -1;
	}
	tm.mday = strtol(s, 0, 10);
	s += 3;

	/* Jan- */
	for(i=0; i<nelem(mon); i++)
		if(cistrncmp(s, mon[i], 3) == 0){
			tm.mon = i;
			s += 3;
			break;
		}
	if(i==nelem(mon)){
		if(cookiedebug)
			fprint(2, "bad month (%s)\n", os);
		return -1;
	}
	if(s[0] != '-' && s[0] != ' '){
		if(cookiedebug)
			fprint(2, "bad month separator (%s)\n", os);
		return -1;
	}
	s++;

	/* 2002 */
	if(!isdigit(s[0]) || !isdigit(s[1])){
		if(cookiedebug)
			fprint(2, "bad year (%s)\n", os);
		return -1;
	}
	tm.year = strtol(s, 0, 10);
	s += 2;
	if(isdigit(s[0]) && isdigit(s[1]))
		s += 2;
	else{
		if(tm.year <= 68)
			tm.year += 2000;
		else
			tm.year += 1900;
	}
	if(tm.mday==0 || tm.mday > mday[isleap(tm.year)][tm.mon]){
		if(cookiedebug)
			fprint(2, "invalid day of month (%s)\n", os);
		return -1;
	}
	tm.year -= 1900;
	if(*s++ != ' '){
		if(cookiedebug)
			fprint(2, "bad year separator (%s)\n", os);
		return -1;
	}

	if(!isdigit(s[0]) || !isdigit(s[1]) || s[2]!=':'
	|| !isdigit(s[3]) || !isdigit(s[4]) || s[5]!=':'
	|| !isdigit(s[6]) || !isdigit(s[7]) || s[8]!=' '){
		if(cookiedebug)
			fprint(2, "bad time (%s)\n", os);
		return -1;
	}

	tm.hour = atoi(s);
	tm.min = atoi(s+3);
	tm.sec = atoi(s+6);
	if(tm.hour >= 24 || tm.min >= 60 || tm.sec >= 60){
		if(cookiedebug)
			fprint(2, "invalid time (%s)\n", os);
		return -1;
	}
	s += 9;

	if(cistrcmp(s, "GMT") != 0){
		if(cookiedebug)
			fprint(2, "time zone not GMT (%s)\n", os);
		return -1;
	}
	strcpy(tm.zone, "GMT");
	tm.yday = 0;
	return tm2sec(&tm);
}

/*
 * skip linear whitespace.  we're a bit more lenient than RFC2616 2.2.
 */
static char*
skipspace(char *s)
{
	while(*s=='\r' || *s=='\n' || *s==' ' || *s=='\t')
		s++;
	return s;
}

/*
 * Try to identify old netscape headers.
 * The old headers:
 *	- didn't allow spaces around the '='
 *	- used an 'Expires' attribute
 *	- had no 'Version' attribute
 *	- had no quotes
 *	- allowed whitespace in values
 *	- apparently separated attr/value pairs with ';' exclusively
 */
static int
isnetscape(char *hdr)
{
	char *s;

	for(s=hdr; (s=strchr(s, '=')) != nil; s++){
		if(isspace(s[1]) || (s > hdr && isspace(s[-1])))
			return 0;
		if(s[1]=='"')
			return 0;
	}
	if(cistrstr(hdr, "version="))
		return 0;
	return 1;
}

/*
 * Parse HTTP response headers, adding cookies to jar.
 * Overwrites the headers.  May overwrite path.
 */
static char* parsecookie(Cookie*, char*, char**, int, char*, char*);
static int
parsehttp(Jar *jar, char *hdr, char *dom, char *path)
{
	static char setcookie[] = "Set-Cookie:";
	char *e, *p, *nextp;
	Cookie c;
	int isns, n;

	isns = isnetscape(hdr);
	n = 0;
	for(p=hdr; p; p=nextp){
		p = skipspace(p);
		if(*p == '\0')
			break;
		nextp = strchr(p, '\n');
		if(nextp != nil)
			*nextp++ = '\0';
		if(cistrncmp(p, setcookie, strlen(setcookie)) != 0)
			continue;
		if(cookiedebug)
			fprint(2, "%s\n", p);
		p = skipspace(p+strlen(setcookie));
		for(; *p; p=skipspace(p)){
			if((e = parsecookie(&c, p, &p, isns, dom, path)) != nil){
				if(cookiedebug)
					fprint(2, "parse cookie: %s\n", e);
				break;
			}
			if((e = isbadcookie(&c, dom, path)) != nil){
				if(cookiedebug)
					fprint(2, "reject cookie; %s\n", e);
				continue;
			}
			addcookie(jar, &c);
			n++;
		}
	}
	return n;
}

static char*
skipquoted(char *s)
{
	/*
	 * Sec 2.2 of RFC2616 defines a "quoted-string" as:
	 *
	 *  quoted-string  = ( <"> *(qdtext | quoted-pair ) <"> )
	 *  qdtext         = <any TEXT except <">>
	 *  quoted-pair    = "\" CHAR
	 *
	 * TEXT is any octet except CTLs, but including LWS;
	 * LWS is [CR LF] 1*(SP | HT);
	 * CHARs are ASCII octets 0-127;  (NOTE: we reject 0's)
	 * CTLs are octets 0-31 and 127;
	 */
	if(*s != '"')
		return s;

	for(s++; 32 <= *s && *s < 127 && *s != '"'; s++)
		if(*s == '\\' && *(s+1) != '\0')
			s++;
	return s;
}

static char*
skiptoken(char *s)
{
	/*
	 * Sec 2.2 of RFC2616 defines a "token" as
 	 *  1*<any CHAR except CTLs or separators>;
	 * CHARs are ASCII octets 0-127;
	 * CTLs are octets 0-31 and 127;
	 * separators are "()<>@,;:\/[]?={}", double-quote, SP (32), and HT (9)
	 */
	while(32 <= *s && *s < 127 && strchr("()<>@,;:[]?={}\" \t\\", *s)==nil)
		s++;

	return s;
}

static char*
skipvalue(char *s, int isns)
{
	char *t;

	/*
	 * An RFC2109 value is an HTTP token or an HTTP quoted string.
	 * Netscape servers ignore the spec and rely on semicolons, apparently.
	 */
	if(isns){
		if((t = strchr(s, ';')) == nil)
			t = s+strlen(s);
		return t;
	}
	if(*s == '"')
		return skipquoted(s);
	return skiptoken(s);
}

/*
 * RMID=80b186bb64c03c65fab767f8; expires=Monday, 10-Feb-2003 04:44:39 GMT;
 *	path=/; domain=.nytimes.com
 */
static char*
parsecookie(Cookie *c, char *p, char **e, int isns, char *dom, char *path)
{
	int i, done;
	char *t, *u, *attr, *val;

	c->expire = ~0;
	memset(c, 0, sizeof *c);

	/* NAME=VALUE */
	t = skiptoken(p);
	c->name = p;
	p = skipspace(t);
	if(*p != '='){
	Badname:
		return "malformed cookie: no NAME=VALUE";
	}
	*t = '\0';
	p = skipspace(p+1);
	t = skipvalue(p, isns);
	if(*t)
		*t++ = '\0';
	c->value = p;
	p = skipspace(t);
	if(c->name[0]=='\0' || c->value[0]=='\0')
		goto Badname;

	done = 0;
	for(; *p && !done; p=skipspace(p)){
		attr = p;
		t = skiptoken(p);
		u = skipspace(t);
		switch(*u){
		case '\0':
			*t = '\0';
			val = p = u;
			break;
		case ';':
			*t = '\0';
			val = "";
			p = u+1;
			break;
		case '=':
			*t = '\0';
			val = skipspace(u+1);
			p = skipvalue(val, isns);
			if(*p==',')
				done = 1;
			if(*p)
				*p++ = '\0';
			break;
		case ',':
			if(!isns){
				val = "";
				p = u;
				*p++ = '\0';
				done = 1;
				break;
			}
		default:
			if(cookiedebug)
				fprint(2, "syntax: %s\n", p);
			return "syntax error";
		}
		for(i=0; i<nelem(stab); i++)
			if(stab[i].ishttp && cistrcmp(stab[i].s, attr)==0)
				*(char**)((uintptr)c+stab[i].offset) = val;
		if(cistrcmp(attr, "expires") == 0){
			if(!isns)
				return "non-netscape cookie has Expires tag";
			if(!val[0])
				return "bad expires tag";
			c->expire = strtotime(val);
			if(c->expire == ~0)
				return "cannot parse netscape expires tag";
		}
		if(cistrcmp(attr, "max-age") == 0)
			c->expire = time(0)+atoi(val);
		if(cistrcmp(attr, "secure") == 0)
			c->secure = 1;
	}

	if(c->dom)
		c->explicitdom = 1;
	else
		c->dom = dom;
	if(c->path)
		c->explicitpath = 1;
	else{
		c->path = path;
		if((t = strchr(c->path, '?')) != 0)
			*t = '\0';
		if((t = strrchr(c->path, '/')) != 0)
			*t = '\0';
	}
	c->netscapestyle = isns;
	*e = p;

	return nil;
}

Jar *jar;

typedef struct Aux Aux;
struct Aux
{
	char *dom;
	char *path;
	char *inhttp;
	char *outhttp;
	char *ctext;
	int rdoff;
};
enum
{
	AuxBuf = 4096,
	MaxCtext = 16*1024*1024,
};

void
cookieopen(Req *r)
{
	char *s, *es;
	int i, sz;
	Aux *a;

	syncjar(jar);
	a = emalloc9p(sizeof(Aux));
	r->fid->aux = a;
	if(r->ifcall.mode&OTRUNC){
		a->ctext = emalloc9p(1);
		a->ctext[0] = '\0';
	}else{
		sz = 256*jar->nc+1024;	/* BUG should do better */
		a->ctext = emalloc9p(sz);
		a->ctext[0] = '\0';
		s = a->ctext;
		es = s+sz;
		for(i=0; i<jar->nc; i++)
			s = seprint(s, es, "%K\n", &jar->c[i]);
	}
	respond(r, nil);
}

void
cookieread(Req *r)
{
	Aux *a;

	a = r->fid->aux;
	readstr(r, a->ctext);
	respond(r, nil);
}

void
cookiewrite(Req *r)
{
	Aux *a;
	int sz;

	a = r->fid->aux;
	sz = r->ifcall.count+r->ifcall.offset;
	if(sz > strlen(a->ctext)){
		if(sz >= MaxCtext){
			respond(r, "cookie file too large");
			return;
		}
		a->ctext = erealloc9p(a->ctext, sz+1);
		a->ctext[sz] = '\0';
	}
	memmove(a->ctext+r->ifcall.offset, r->ifcall.data, r->ifcall.count);
	r->ofcall.count = r->ifcall.count;
	respond(r, nil);
}

void
cookieclunk(Fid *fid)
{
	char *p, *nextp;
	Aux *a;
	int i;

	a = fid->aux;
	if(a == nil)
		return;
	for(i=0; i<jar->nc; i++)
		jar->c[i].mark = 1;
	for(p=a->ctext; *p; p=nextp){
		if((nextp = strchr(p, '\n')) != nil)
			*nextp++ = '\0';
		else
			nextp = "";
		addtojar(jar, p, 0);
	}
	for(i=0; i<jar->nc; i++)
		if(jar->c[i].mark)
			delcookie(jar, &jar->c[i]);
	syncjar(jar);
	free(a->dom);
	free(a->path);
	free(a->inhttp);
	free(a->outhttp);
	free(a->ctext);
	free(a);
}

void
closecookies(void)
{
	closejar(jar);
}

void
initcookies(char *file)
{
	char *home;

	fmtinstall('J', jarfmt);
	fmtinstall('K', cookiefmt);

	if(file == nil){
		home = getenv("home");
		if(home == nil)
			sysfatal("no cookie file specified and no $home");
		file = emalloc9p(strlen(home)+30);
		strcpy(file, home);
		strcat(file, "/lib/webcookies");
	}
	jar = readjar(file);
	if(jar == nil)
		sysfatal("readjar: %r");
}

void
httpsetcookie(char *hdr, char *dom, char *path)
{
	if(path == nil)
		path = "/";

	parsehttp(jar, hdr, dom, path);
	syncjar(jar);
}

char*
httpcookies(char *dom, char *path, int issecure)
{
	char buf[1024];
	Jar *j;

	syncjar(jar);
	j = cookiesearch(jar, dom, path, issecure);
	snprint(buf, sizeof buf, "%J", j);
	closejar(j);
	return estrdup(buf);
}