src/pkg/net/http/cookiejar/jar.go - go - Git at Google

 // Copyright 2012 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.

 // Package cookiejar implements an in-memory RFC 6265-compliant http.CookieJar.
 package cookiejar

 import (
 	"errors"
 	"fmt"
 	"net"
 	"net/http"
 	"net/url"
 	"sort"
 	"strings"
 	"sync"
 	"time"
 )

 // PublicSuffixList provides the public suffix of a domain. For example:
 //      - the public suffix of "example.com" is "com",
 //      - the public suffix of "foo1.foo2.foo3.co.uk" is "co.uk", and
 //      - the public suffix of "bar.pvt.k12.ma.us" is "pvt.k12.ma.us".
 //
 // Implementations of PublicSuffixList must be safe for concurrent use by
 // multiple goroutines.
 //
 // An implementation that always returns "" is valid and may be useful for
 // testing but it is not secure: it means that the HTTP server for foo.com can
 // set a cookie for bar.com.
 //
 // A public suffix list implementation is in the package
 // code.google.com/p/go.net/publicsuffix.
 type PublicSuffixList interface {
 	// PublicSuffix returns the public suffix of domain.
 	//
 	// TODO: specify which of the caller and callee is responsible for IP
 	// addresses, for leading and trailing dots, for case sensitivity, and
 	// for IDN/Punycode.
 	PublicSuffix(domain string) string

 	// String returns a description of the source of this public suffix
 	// list. The description will typically contain something like a time
 	// stamp or version number.
 	String() string
 }

 // Options are the options for creating a new Jar.
 type Options struct {
 	// PublicSuffixList is the public suffix list that determines whether
 	// an HTTP server can set a cookie for a domain.
 	//
 	// A nil value is valid and may be useful for testing but it is not
 	// secure: it means that the HTTP server for foo.co.uk can set a cookie
 	// for bar.co.uk.
 	PublicSuffixList PublicSuffixList
 }

 // Jar implements the http.CookieJar interface from the net/http package.
 type Jar struct {
 	psList PublicSuffixList

 	// mu locks the remaining fields.
 	mu sync.Mutex

 	// entries is a set of entries, keyed by their eTLD+1 and subkeyed by
 	// their name/domain/path.
 	entries map[string]map[string]entry

 	// nextSeqNum is the next sequence number assigned to a new cookie
 	// created SetCookies.
 	nextSeqNum uint64
 }

 // New returns a new cookie jar. A nil *Options is equivalent to a zero
 // Options.
 func New(o *Options) (*Jar, error) {
 	jar := &Jar{
 		entries: make(map[string]map[string]entry),
 	}
 	if o != nil {
 		jar.psList = o.PublicSuffixList
 	}
 	return jar, nil
 }

 // entry is the internal representation of a cookie.
 //
 // This struct type is not used outside of this package per se, but the exported
 // fields are those of RFC 6265.
 type entry struct {
 	Name       string
 	Value      string
 	Domain     string
 	Path       string
 	Secure     bool
 	HttpOnly   bool
 	Persistent bool
 	HostOnly   bool
 	Expires    time.Time
 	Creation   time.Time
 	LastAccess time.Time

 	// seqNum is a sequence number so that Cookies returns cookies in a
 	// deterministic order, even for cookies that have equal Path length and
 	// equal Creation time. This simplifies testing.
 	seqNum uint64
 }

 // Id returns the domain;path;name triple of e as an id.
 func (e *entry) id() string {
 	return fmt.Sprintf("%s;%s;%s", e.Domain, e.Path, e.Name)
 }

 // shouldSend determines whether e's cookie qualifies to be included in a
 // request to host/path. It is the caller's responsibility to check if the
 // cookie is expired.
 func (e *entry) shouldSend(https bool, host, path string) bool {
 	return e.domainMatch(host) && e.pathMatch(path) && (https || !e.Secure)
 }

 // domainMatch implements "domain-match" of RFC 6265 section 5.1.3.
 func (e *entry) domainMatch(host string) bool {
 	if e.Domain == host {
 		return true
 	}
 	return !e.HostOnly && hasDotSuffix(host, e.Domain)
 }

 // pathMatch implements "path-match" according to RFC 6265 section 5.1.4.
 func (e *entry) pathMatch(requestPath string) bool {
 	if requestPath == e.Path {
 		return true
 	}
 	if strings.HasPrefix(requestPath, e.Path) {
 		if e.Path[len(e.Path)-1] == '/' {
 			return true // The "/any/" matches "/any/path" case.
 		} else if requestPath[len(e.Path)] == '/' {
 			return true // The "/any" matches "/any/path" case.
 		}
 	}
 	return false
 }

 // hasDotSuffix reports whether s ends in "."+suffix.
 func hasDotSuffix(s, suffix string) bool {
 	return len(s) > len(suffix) && s[len(s)-len(suffix)-1] == '.' && s[len(s)-len(suffix):] == suffix
 }

 // byPathLength is a []entry sort.Interface that sorts according to RFC 6265
 // section 5.4 point 2: by longest path and then by earliest creation time.
 type byPathLength []entry

 func (s byPathLength) Len() int { return len(s) }

 func (s byPathLength) Less(i, j int) bool {
 	if len(s[i].Path) != len(s[j].Path) {
 		return len(s[i].Path) > len(s[j].Path)
 	}
 	if !s[i].Creation.Equal(s[j].Creation) {
 		return s[i].Creation.Before(s[j].Creation)
 	}
 	return s[i].seqNum < s[j].seqNum
 }

 func (s byPathLength) Swap(i, j int) { s[i], s[j] = s[j], s[i] }

 // Cookies implements the Cookies method of the http.CookieJar interface.
 //
 // It returns an empty slice if the URL's scheme is not HTTP or HTTPS.
 func (j *Jar) Cookies(u *url.URL) (cookies []*http.Cookie) {
 	return j.cookies(u, time.Now())
 }

 // cookies is like Cookies but takes the current time as a parameter.
 func (j *Jar) cookies(u *url.URL, now time.Time) (cookies []*http.Cookie) {
 	if u.Scheme != "http" && u.Scheme != "https" {
 		return cookies
 	}
 	host, err := canonicalHost(u.Host)
 	if err != nil {
 		return cookies
 	}
 	key := jarKey(host, j.psList)

 	j.mu.Lock()
 	defer j.mu.Unlock()

 	submap := j.entries[key]
 	if submap == nil {
 		return cookies
 	}

 	https := u.Scheme == "https"
 	path := u.Path
 	if path == "" {
 		path = "/"
 	}

 	modified := false
 	var selected []entry
 	for id, e := range submap {
 		if e.Persistent && !e.Expires.After(now) {
 			delete(submap, id)
 			modified = true
 			continue
 		}
 		if !e.shouldSend(https, host, path) {
 			continue
 		}
 		e.LastAccess = now
 		submap[id] = e
 		selected = append(selected, e)
 		modified = true
 	}
 	if modified {
 		if len(submap) == 0 {
 			delete(j.entries, key)
 		} else {
 			j.entries[key] = submap
 		}
 	}

 	sort.Sort(byPathLength(selected))
 	for _, e := range selected {
 		cookies = append(cookies, &http.Cookie{Name: e.Name, Value: e.Value})
 	}

 	return cookies
 }

 // SetCookies implements the SetCookies method of the http.CookieJar interface.
 //
 // It does nothing if the URL's scheme is not HTTP or HTTPS.
 func (j *Jar) SetCookies(u *url.URL, cookies []*http.Cookie) {
 	j.setCookies(u, cookies, time.Now())
 }

 // setCookies is like SetCookies but takes the current time as parameter.
 func (j *Jar) setCookies(u *url.URL, cookies []*http.Cookie, now time.Time) {
 	if len(cookies) == 0 {
 		return
 	}
 	if u.Scheme != "http" && u.Scheme != "https" {
 		return
 	}
 	host, err := canonicalHost(u.Host)
 	if err != nil {
 		return
 	}
 	key := jarKey(host, j.psList)
 	defPath := defaultPath(u.Path)

 	j.mu.Lock()
 	defer j.mu.Unlock()

 	submap := j.entries[key]

 	modified := false
 	for _, cookie := range cookies {
 		e, remove, err := j.newEntry(cookie, now, defPath, host)
 		if err != nil {
 			continue
 		}
 		id := e.id()
 		if remove {
 			if submap != nil {
 				if _, ok := submap[id]; ok {
 					delete(submap, id)
 					modified = true
 				}
 			}
 			continue
 		}
 		if submap == nil {
 			submap = make(map[string]entry)
 		}

 		if old, ok := submap[id]; ok {
 			e.Creation = old.Creation
 			e.seqNum = old.seqNum
 		} else {
 			e.Creation = now
 			e.seqNum = j.nextSeqNum
 			j.nextSeqNum++
 		}
 		e.LastAccess = now
 		submap[id] = e
 		modified = true
 	}

 	if modified {
 		if len(submap) == 0 {
 			delete(j.entries, key)
 		} else {
 			j.entries[key] = submap
 		}
 	}
 }

 // canonicalHost strips port from host if present and returns the canonicalized
 // host name.
 func canonicalHost(host string) (string, error) {
 	var err error
 	host = strings.ToLower(host)
 	if hasPort(host) {
 		host, _, err = net.SplitHostPort(host)
 		if err != nil {
 			return "", err
 		}
 	}
 	if strings.HasSuffix(host, ".") {
 		// Strip trailing dot from fully qualified domain names.
 		host = host[:len(host)-1]
 	}
 	return toASCII(host)
 }

 // hasPort reports whether host contains a port number. host may be a host
 // name, an IPv4 or an IPv6 address.
 func hasPort(host string) bool {
 	colons := strings.Count(host, ":")
 	if colons == 0 {
 		return false
 	}
 	if colons == 1 {
 		return true
 	}
 	return host[0] == '[' && strings.Contains(host, "]:")
 }

 // jarKey returns the key to use for a jar.
 func jarKey(host string, psl PublicSuffixList) string {
 	if isIP(host) {
 		return host
 	}

 	var i int
 	if psl == nil {
 		i = strings.LastIndex(host, ".")
 		if i == -1 {
 			return host
 		}
 	} else {
 		suffix := psl.PublicSuffix(host)
 		if suffix == host {
 			return host
 		}
 		i = len(host) - len(suffix)
 		if i <= 0 || host[i-1] != '.' {
 			// The provided public suffix list psl is broken.
 			// Storing cookies under host is a safe stopgap.
 			return host
 		}
 	}
 	prevDot := strings.LastIndex(host[:i-1], ".")
 	return host[prevDot+1:]
 }

 // isIP reports whether host is an IP address.
 func isIP(host string) bool {
 	return net.ParseIP(host) != nil
 }

 // defaultPath returns the directory part of an URL's path according to
 // RFC 6265 section 5.1.4.
 func defaultPath(path string) string {
 	if len(path) == 0 || path[0] != '/' {
 		return "/" // Path is empty or malformed.
 	}

 	i := strings.LastIndex(path, "/") // Path starts with "/", so i != -1.
 	if i == 0 {
 		return "/" // Path has the form "/abc".
 	}
 	return path[:i] // Path is either of form "/abc/xyz" or "/abc/xyz/".
 }

 // newEntry creates an entry from a http.Cookie c. now is the current time and
 // is compared to c.Expires to determine deletion of c. defPath and host are the
 // default-path and the canonical host name of the URL c was received from.
 //
 // remove records whether the jar should delete this cookie, as it has already
 // expired with respect to now. In this case, e may be incomplete, but it will
 // be valid to call e.id (which depends on e's Name, Domain and Path).
 //
 // A malformed c.Domain will result in an error.
 func (j *Jar) newEntry(c *http.Cookie, now time.Time, defPath, host string) (e entry, remove bool, err error) {
 	e.Name = c.Name

 	if c.Path == "" || c.Path[0] != '/' {
 		e.Path = defPath
 	} else {
 		e.Path = c.Path
 	}

 	e.Domain, e.HostOnly, err = j.domainAndType(host, c.Domain)
 	if err != nil {
 		return e, false, err
 	}

 	// MaxAge takes precedence over Expires.
 	if c.MaxAge < 0 {
 		return e, true, nil
 	} else if c.MaxAge > 0 {
 		e.Expires = now.Add(time.Duration(c.MaxAge) * time.Second)
 		e.Persistent = true
 	} else {
 		if c.Expires.IsZero() {
 			e.Expires = endOfTime
 			e.Persistent = false
 		} else {
 			if !c.Expires.After(now) {
 				return e, true, nil
 			}
 			e.Expires = c.Expires
 			e.Persistent = true
 		}
 	}

 	e.Value = c.Value
 	e.Secure = c.Secure
 	e.HttpOnly = c.HttpOnly

 	return e, false, nil
 }

 var (
 	errIllegalDomain   = errors.New("cookiejar: illegal cookie domain attribute")
 	errMalformedDomain = errors.New("cookiejar: malformed cookie domain attribute")
 	errNoHostname      = errors.New("cookiejar: no host name available (IP only)")
 )

 // endOfTime is the time when session (non-persistent) cookies expire.
 // This instant is representable in most date/time formats (not just
 // Go's time.Time) and should be far enough in the future.
 var endOfTime = time.Date(9999, 12, 31, 23, 59, 59, 0, time.UTC)

 // domainAndType determines the cookie's domain and hostOnly attribute.
 func (j *Jar) domainAndType(host, domain string) (string, bool, error) {
 	if domain == "" {
 		// No domain attribute in the SetCookie header indicates a
 		// host cookie.
 		return host, true, nil
 	}

 	if isIP(host) {
 		// According to RFC 6265 domain-matching includes not being
 		// an IP address.
 		// TODO: This might be relaxed as in common browsers.
 		return "", false, errNoHostname
 	}

 	// From here on: If the cookie is valid, it is a domain cookie (with
 	// the one exception of a public suffix below).
 	// See RFC 6265 section 5.2.3.
 	if domain[0] == '.' {
 		domain = domain[1:]
 	}

 	if len(domain) == 0 || domain[0] == '.' {
 		// Received either "Domain=." or "Domain=..some.thing",
 		// both are illegal.
 		return "", false, errMalformedDomain
 	}
 	domain = strings.ToLower(domain)

 	if domain[len(domain)-1] == '.' {
 		// We received stuff like "Domain=www.example.com.".
 		// Browsers do handle such stuff (actually differently) but
 		// RFC 6265 seems to be clear here (e.g. section 4.1.2.3) in
 		// requiring a reject.  4.1.2.3 is not normative, but
 		// "Domain Matching" (5.1.3) and "Canonicalized Host Names"
 		// (5.1.2) are.
 		return "", false, errMalformedDomain
 	}

 	// See RFC 6265 section 5.3 #5.
 	if j.psList != nil {
 		if ps := j.psList.PublicSuffix(domain); ps != "" && !hasDotSuffix(domain, ps) {
 			if host == domain {
 				// This is the one exception in which a cookie
 				// with a domain attribute is a host cookie.
 				return host, true, nil
 			}
 			return "", false, errIllegalDomain
 		}
 	}

 	// The domain must domain-match host: www.mycompany.com cannot
 	// set cookies for .ourcompetitors.com.
 	if host != domain && !hasDotSuffix(host, domain) {
 		return "", false, errIllegalDomain
 	}

 	return domain, false, nil
 }
	// Copyright 2012 The Go Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style
	// license that can be found in the LICENSE file.

	// Package cookiejar implements an in-memory RFC 6265-compliant http.CookieJar.
	package cookiejar

	import (
	"errors"
	"fmt"
	"net"
	"net/http"
	"net/url"
	"sort"
	"strings"
	"sync"
	"time"
	)

	// PublicSuffixList provides the public suffix of a domain. For example:
	// - the public suffix of "example.com" is "com",
	// - the public suffix of "foo1.foo2.foo3.co.uk" is "co.uk", and
	// - the public suffix of "bar.pvt.k12.ma.us" is "pvt.k12.ma.us".
	//
	// Implementations of PublicSuffixList must be safe for concurrent use by
	// multiple goroutines.
	//
	// An implementation that always returns "" is valid and may be useful for
	// testing but it is not secure: it means that the HTTP server for foo.com can
	// set a cookie for bar.com.
	//
	// A public suffix list implementation is in the package
	// code.google.com/p/go.net/publicsuffix.
	type PublicSuffixList interface {
	// PublicSuffix returns the public suffix of domain.
	//
	// TODO: specify which of the caller and callee is responsible for IP
	// addresses, for leading and trailing dots, for case sensitivity, and
	// for IDN/Punycode.
	PublicSuffix(domain string) string

	// String returns a description of the source of this public suffix
	// list. The description will typically contain something like a time
	// stamp or version number.
	String() string
	}

	// Options are the options for creating a new Jar.
	type Options struct {
	// PublicSuffixList is the public suffix list that determines whether
	// an HTTP server can set a cookie for a domain.
	//
	// A nil value is valid and may be useful for testing but it is not
	// secure: it means that the HTTP server for foo.co.uk can set a cookie
	// for bar.co.uk.
	PublicSuffixList PublicSuffixList
	}

	// Jar implements the http.CookieJar interface from the net/http package.
	type Jar struct {
	psList PublicSuffixList

	// mu locks the remaining fields.
	mu sync.Mutex

	// entries is a set of entries, keyed by their eTLD+1 and subkeyed by
	// their name/domain/path.
	entries map[string]map[string]entry

	// nextSeqNum is the next sequence number assigned to a new cookie
	// created SetCookies.
	nextSeqNum uint64
	}

	// New returns a new cookie jar. A nil *Options is equivalent to a zero
	// Options.
	func New(o Options) (Jar, error) {
	jar := &Jar{
	entries: make(map[string]map[string]entry),
	}
	if o != nil {
	jar.psList = o.PublicSuffixList
	}
	return jar, nil
	}

	// entry is the internal representation of a cookie.
	//
	// This struct type is not used outside of this package per se, but the exported
	// fields are those of RFC 6265.
	type entry struct {
	Name string
	Value string
	Domain string
	Path string
	Secure bool
	HttpOnly bool
	Persistent bool
	HostOnly bool
	Expires time.Time
	Creation time.Time
	LastAccess time.Time

	// seqNum is a sequence number so that Cookies returns cookies in a
	// deterministic order, even for cookies that have equal Path length and
	// equal Creation time. This simplifies testing.
	seqNum uint64
	}

	// Id returns the domain;path;name triple of e as an id.
	func (e *entry) id() string {
	return fmt.Sprintf("%s;%s;%s", e.Domain, e.Path, e.Name)
	}

	// shouldSend determines whether e's cookie qualifies to be included in a
	// request to host/path. It is the caller's responsibility to check if the
	// cookie is expired.
	func (e *entry) shouldSend(https bool, host, path string) bool {
	return e.domainMatch(host) && e.pathMatch(path) && (https \|\| !e.Secure)
	}

	// domainMatch implements "domain-match" of RFC 6265 section 5.1.3.
	func (e *entry) domainMatch(host string) bool {
	if e.Domain == host {
	return true
	}
	return !e.HostOnly && hasDotSuffix(host, e.Domain)
	}

	// pathMatch implements "path-match" according to RFC 6265 section 5.1.4.
	func (e *entry) pathMatch(requestPath string) bool {
	if requestPath == e.Path {
	return true
	}
	if strings.HasPrefix(requestPath, e.Path) {
	if e.Path[len(e.Path)-1] == '/' {
	return true // The "/any/" matches "/any/path" case.
	} else if requestPath[len(e.Path)] == '/' {
	return true // The "/any" matches "/any/path" case.
	}
	}
	return false
	}

	// hasDotSuffix reports whether s ends in "."+suffix.
	func hasDotSuffix(s, suffix string) bool {
	return len(s) > len(suffix) && s[len(s)-len(suffix)-1] == '.' && s[len(s)-len(suffix):] == suffix
	}

	// byPathLength is a []entry sort.Interface that sorts according to RFC 6265
	// section 5.4 point 2: by longest path and then by earliest creation time.
	type byPathLength []entry

	func (s byPathLength) Len() int { return len(s) }

	func (s byPathLength) Less(i, j int) bool {
	if len(s[i].Path) != len(s[j].Path) {
	return len(s[i].Path) > len(s[j].Path)
	}
	if !s[i].Creation.Equal(s[j].Creation) {
	return s[i].Creation.Before(s[j].Creation)
	}
	return s[i].seqNum < s[j].seqNum
	}

	func (s byPathLength) Swap(i, j int) { s[i], s[j] = s[j], s[i] }

	// Cookies implements the Cookies method of the http.CookieJar interface.
	//
	// It returns an empty slice if the URL's scheme is not HTTP or HTTPS.
	func (j Jar) Cookies(u url.URL) (cookies []*http.Cookie) {
	return j.cookies(u, time.Now())
	}

	// cookies is like Cookies but takes the current time as a parameter.
	func (j Jar) cookies(u url.URL, now time.Time) (cookies []*http.Cookie) {
	if u.Scheme != "http" && u.Scheme != "https" {
	return cookies
	}
	host, err := canonicalHost(u.Host)
	if err != nil {
	return cookies
	}
	key := jarKey(host, j.psList)

	j.mu.Lock()
	defer j.mu.Unlock()

	submap := j.entries[key]
	if submap == nil {
	return cookies
	}

	https := u.Scheme == "https"
	path := u.Path
	if path == "" {
	path = "/"
	}

	modified := false
	var selected []entry
	for id, e := range submap {
	if e.Persistent && !e.Expires.After(now) {
	delete(submap, id)
	modified = true
	continue
	}
	if !e.shouldSend(https, host, path) {
	continue
	}
	e.LastAccess = now
	submap[id] = e
	selected = append(selected, e)
	modified = true
	}
	if modified {
	if len(submap) == 0 {
	delete(j.entries, key)
	} else {
	j.entries[key] = submap
	}
	}

	sort.Sort(byPathLength(selected))
	for _, e := range selected {
	cookies = append(cookies, &http.Cookie{Name: e.Name, Value: e.Value})
	}

	return cookies
	}

	// SetCookies implements the SetCookies method of the http.CookieJar interface.
	//
	// It does nothing if the URL's scheme is not HTTP or HTTPS.
	func (j Jar) SetCookies(u url.URL, cookies []*http.Cookie) {
	j.setCookies(u, cookies, time.Now())
	}

	// setCookies is like SetCookies but takes the current time as parameter.
	func (j Jar) setCookies(u url.URL, cookies []*http.Cookie, now time.Time) {
	if len(cookies) == 0 {
	return
	}
	if u.Scheme != "http" && u.Scheme != "https" {
	return
	}
	host, err := canonicalHost(u.Host)
	if err != nil {
	return
	}
	key := jarKey(host, j.psList)
	defPath := defaultPath(u.Path)

	j.mu.Lock()
	defer j.mu.Unlock()

	submap := j.entries[key]

	modified := false
	for _, cookie := range cookies {
	e, remove, err := j.newEntry(cookie, now, defPath, host)
	if err != nil {
	continue
	}
	id := e.id()
	if remove {
	if submap != nil {
	if _, ok := submap[id]; ok {
	delete(submap, id)
	modified = true
	}
	}
	continue
	}
	if submap == nil {
	submap = make(map[string]entry)
	}

	if old, ok := submap[id]; ok {
	e.Creation = old.Creation
	e.seqNum = old.seqNum
	} else {
	e.Creation = now
	e.seqNum = j.nextSeqNum
	j.nextSeqNum++
	}
	e.LastAccess = now
	submap[id] = e
	modified = true
	}

	if modified {
	if len(submap) == 0 {
	delete(j.entries, key)
	} else {
	j.entries[key] = submap
	}
	}
	}

	// canonicalHost strips port from host if present and returns the canonicalized
	// host name.
	func canonicalHost(host string) (string, error) {
	var err error
	host = strings.ToLower(host)
	if hasPort(host) {
	host, _, err = net.SplitHostPort(host)
	if err != nil {
	return "", err
	}
	}
	if strings.HasSuffix(host, ".") {
	// Strip trailing dot from fully qualified domain names.
	host = host[:len(host)-1]
	}
	return toASCII(host)
	}

	// hasPort reports whether host contains a port number. host may be a host
	// name, an IPv4 or an IPv6 address.
	func hasPort(host string) bool {
	colons := strings.Count(host, ":")
	if colons == 0 {
	return false
	}
	if colons == 1 {
	return true
	}
	return host[0] == '[' && strings.Contains(host, "]:")
	}

	// jarKey returns the key to use for a jar.
	func jarKey(host string, psl PublicSuffixList) string {
	if isIP(host) {
	return host
	}

	var i int
	if psl == nil {
	i = strings.LastIndex(host, ".")
	if i == -1 {
	return host
	}
	} else {
	suffix := psl.PublicSuffix(host)
	if suffix == host {
	return host
	}
	i = len(host) - len(suffix)
	if i <= 0 \|\| host[i-1] != '.' {
	// The provided public suffix list psl is broken.
	// Storing cookies under host is a safe stopgap.
	return host
	}
	}
	prevDot := strings.LastIndex(host[:i-1], ".")
	return host[prevDot+1:]
	}

	// isIP reports whether host is an IP address.
	func isIP(host string) bool {
	return net.ParseIP(host) != nil
	}

	// defaultPath returns the directory part of an URL's path according to
	// RFC 6265 section 5.1.4.
	func defaultPath(path string) string {
	if len(path) == 0 \|\| path[0] != '/' {
	return "/" // Path is empty or malformed.
	}

	i := strings.LastIndex(path, "/") // Path starts with "/", so i != -1.
	if i == 0 {
	return "/" // Path has the form "/abc".
	}
	return path[:i] // Path is either of form "/abc/xyz" or "/abc/xyz/".
	}

	// newEntry creates an entry from a http.Cookie c. now is the current time and
	// is compared to c.Expires to determine deletion of c. defPath and host are the
	// default-path and the canonical host name of the URL c was received from.
	//
	// remove records whether the jar should delete this cookie, as it has already
	// expired with respect to now. In this case, e may be incomplete, but it will
	// be valid to call e.id (which depends on e's Name, Domain and Path).
	//
	// A malformed c.Domain will result in an error.
	func (j Jar) newEntry(c http.Cookie, now time.Time, defPath, host string) (e entry, remove bool, err error) {
	e.Name = c.Name

	if c.Path == "" \|\| c.Path[0] != '/' {
	e.Path = defPath
	} else {
	e.Path = c.Path
	}

	e.Domain, e.HostOnly, err = j.domainAndType(host, c.Domain)
	if err != nil {
	return e, false, err
	}

	// MaxAge takes precedence over Expires.
	if c.MaxAge < 0 {
	return e, true, nil
	} else if c.MaxAge > 0 {
	e.Expires = now.Add(time.Duration(c.MaxAge) * time.Second)
	e.Persistent = true
	} else {
	if c.Expires.IsZero() {
	e.Expires = endOfTime
	e.Persistent = false
	} else {
	if !c.Expires.After(now) {
	return e, true, nil
	}
	e.Expires = c.Expires
	e.Persistent = true
	}
	}

	e.Value = c.Value
	e.Secure = c.Secure
	e.HttpOnly = c.HttpOnly

	return e, false, nil
	}

	var (
	errIllegalDomain = errors.New("cookiejar: illegal cookie domain attribute")
	errMalformedDomain = errors.New("cookiejar: malformed cookie domain attribute")
	errNoHostname = errors.New("cookiejar: no host name available (IP only)")
	)

	// endOfTime is the time when session (non-persistent) cookies expire.
	// This instant is representable in most date/time formats (not just
	// Go's time.Time) and should be far enough in the future.
	var endOfTime = time.Date(9999, 12, 31, 23, 59, 59, 0, time.UTC)

	// domainAndType determines the cookie's domain and hostOnly attribute.
	func (j *Jar) domainAndType(host, domain string) (string, bool, error) {
	if domain == "" {
	// No domain attribute in the SetCookie header indicates a
	// host cookie.
	return host, true, nil
	}

	if isIP(host) {
	// According to RFC 6265 domain-matching includes not being
	// an IP address.
	// TODO: This might be relaxed as in common browsers.
	return "", false, errNoHostname
	}

	// From here on: If the cookie is valid, it is a domain cookie (with
	// the one exception of a public suffix below).
	// See RFC 6265 section 5.2.3.
	if domain[0] == '.' {
	domain = domain[1:]
	}

	if len(domain) == 0 \|\| domain[0] == '.' {
	// Received either "Domain=." or "Domain=..some.thing",
	// both are illegal.
	return "", false, errMalformedDomain
	}
	domain = strings.ToLower(domain)

	if domain[len(domain)-1] == '.' {
	// We received stuff like "Domain=www.example.com.".
	// Browsers do handle such stuff (actually differently) but
	// RFC 6265 seems to be clear here (e.g. section 4.1.2.3) in
	// requiring a reject. 4.1.2.3 is not normative, but
	// "Domain Matching" (5.1.3) and "Canonicalized Host Names"
	// (5.1.2) are.
	return "", false, errMalformedDomain
	}

	// See RFC 6265 section 5.3 #5.
	if j.psList != nil {
	if ps := j.psList.PublicSuffix(domain); ps != "" && !hasDotSuffix(domain, ps) {
	if host == domain {
	// This is the one exception in which a cookie
	// with a domain attribute is a host cookie.
	return host, true, nil
	}
	return "", false, errIllegalDomain
	}
	}

	// The domain must domain-match host: www.mycompany.com cannot
	// set cookies for .ourcompetitors.com.
	if host != domain && !hasDotSuffix(host, domain) {
	return "", false, errIllegalDomain
	}

	return domain, false, nil
	}