mox/imapserver/parse.go
Mechiel Lukkien 7f1b7198a8
add condstore & qresync imap extensions
for conditional storing and quick resynchronisation (not sure if mail clients are actually using it that).

each message now has a "modseq". it is increased for each change. with
condstore, imap clients can request changes since a certain modseq. that
already allows quickly finding changes since a previous connection. condstore
also allows storing (e.g. setting new message flags) only when the modseq of a
message hasn't changed.

qresync should make it fast for clients to get a full list of changed messages
for a mailbox, including removals.

we now also keep basic metadata of messages that have been removed (expunged).
just enough (uid, modseq) to tell client that the messages have been removed.
this does mean we have to be careful when querying messages from the database.
we must now often filter the expunged messages out.

we also keep "createseq", the modseq when a message was created. this will be
useful for the jmap implementation.
2023-07-24 21:25:50 +02:00

945 lines
20 KiB
Go

package imapserver
import (
"errors"
"fmt"
"net/textproto"
"strconv"
"strings"
"time"
"github.com/mjl-/mox/mlog"
)
var (
listWildcards = "%*"
char = charRange('\x01', '\x7f')
ctl = charRange('\x01', '\x19')
quotedSpecials = `"\`
respSpecials = "]"
atomChar = charRemove(char, "(){ "+ctl+listWildcards+quotedSpecials+respSpecials)
astringChar = atomChar + respSpecials
)
func charRange(first, last rune) string {
r := ""
c := first
r += string(c)
for c < last {
c++
r += string(c)
}
return r
}
func charRemove(s, remove string) string {
r := ""
next:
for _, c := range s {
for _, x := range remove {
if c == x {
continue next
}
}
r += string(c)
}
return r
}
type parser struct {
// Orig is the line in original casing, and upper in upper casing. We often match
// against upper for easy case insensitive handling as IMAP requires, but sometimes
// return from orig to keep the original case.
orig string
upper string
o int // Current offset in parsing.
contexts []string // What we're parsing, for error messages.
conn *conn
}
// toUpper upper cases bytes that are a-z. strings.ToUpper does too much. and
// would replace invalid bytes with unicode replacement characters, which would
// break our requirement that offsets into the original and upper case strings
// point to the same character.
func toUpper(s string) string {
r := []byte(s)
for i, c := range r {
if c >= 'a' && c <= 'z' {
r[i] = c - 0x20
}
}
return string(r)
}
func newParser(s string, conn *conn) *parser {
return &parser{s, toUpper(s), 0, nil, conn}
}
func (p *parser) xerrorf(format string, args ...any) {
var err error
errmsg := fmt.Sprintf(format, args...)
remaining := fmt.Sprintf("remaining %q", p.orig[p.o:])
if len(p.contexts) > 0 {
remaining += ", context " + strings.Join(p.contexts, ",")
}
remaining = " (" + remaining + ")"
if p.conn.account != nil {
errmsg += remaining
err = errors.New(errmsg)
} else {
err = errors.New(errmsg + remaining)
}
panic(syntaxError{"", "", errmsg, err})
}
func (p *parser) context(s string) func() {
p.contexts = append(p.contexts, s)
return func() {
p.contexts = p.contexts[:len(p.contexts)-1]
}
}
func (p *parser) empty() bool {
return p.o == len(p.upper)
}
func (p *parser) xempty() {
if !p.empty() {
p.xerrorf("leftover data")
}
}
func (p *parser) hasPrefix(s string) bool {
return strings.HasPrefix(p.upper[p.o:], s)
}
func (p *parser) take(s string) bool {
if !p.hasPrefix(s) {
return false
}
p.o += len(s)
return true
}
func (p *parser) xtake(s string) {
if !p.take(s) {
p.xerrorf("expected %s", s)
}
}
func (p *parser) xnonempty() {
if p.empty() {
p.xerrorf("unexpected end")
}
}
func (p *parser) xtakeall() string {
r := p.orig[p.o:]
p.o = len(p.orig)
return r
}
func (p *parser) xtake1n(n int, what string) string {
if n == 0 {
p.xerrorf("expected chars from %s", what)
}
return p.xtaken(n)
}
func (p *parser) xtakechars(s string, what string) string {
p.xnonempty()
for i, c := range p.orig[p.o:] {
if !contains(s, c) {
return p.xtake1n(i, what)
}
}
return p.xtakeall()
}
func (p *parser) xtaken(n int) string {
if p.o+n > len(p.orig) {
p.xerrorf("not enough data")
}
r := p.orig[p.o : p.o+n]
p.o += n
return r
}
func (p *parser) space() bool {
return p.take(" ")
}
func (p *parser) xspace() {
if !p.space() {
p.xerrorf("expected space")
}
}
func (p *parser) digits() string {
var n int
for _, c := range p.upper[p.o:] {
if c < '0' || c > '9' {
break
}
n++
}
if n == 0 {
return ""
}
s := p.upper[p.o : p.o+n]
p.o += n
return s
}
func (p *parser) nznumber() (uint32, bool) {
o := p.o
for o < len(p.upper) && p.upper[o] >= '0' && p.upper[o] <= '9' {
o++
}
if o == p.o {
return 0, false
}
if n, err := strconv.ParseUint(p.upper[p.o:o], 10, 32); err != nil {
return 0, false
} else if n == 0 {
return 0, false
} else {
p.o = o
return uint32(n), true
}
}
func (p *parser) xnznumber() uint32 {
n, ok := p.nznumber()
if !ok {
p.xerrorf("expected non-zero number")
}
return n
}
func (p *parser) number() (uint32, bool) {
o := p.o
for o < len(p.upper) && p.upper[o] >= '0' && p.upper[o] <= '9' {
o++
}
if o == p.o {
return 0, false
}
n, err := strconv.ParseUint(p.upper[p.o:o], 10, 32)
if err != nil {
return 0, false
}
p.o = o
return uint32(n), true
}
func (p *parser) xnumber() uint32 {
n, ok := p.number()
if !ok {
p.xerrorf("expected number")
}
return n
}
func (p *parser) xnumber64() int64 {
s := p.digits()
if s == "" {
p.xerrorf("expected number64")
}
v, err := strconv.ParseInt(s, 10, 63) // ../rfc/9051:6794 ../rfc/7162:297
if err != nil {
p.xerrorf("parsing number64 %q: %v", s, err)
}
return v
}
func (p *parser) xnznumber64() int64 {
v := p.xnumber64()
if v == 0 {
p.xerrorf("expected non-zero number64")
}
return v
}
// l should be a list of uppercase words, the first match is returned
func (p *parser) takelist(l ...string) (string, bool) {
for _, w := range l {
if p.take(w) {
return w, true
}
}
return "", false
}
func (p *parser) xtakelist(l ...string) string {
w, ok := p.takelist(l...)
if !ok {
p.xerrorf("expected one of %s", strings.Join(l, ","))
}
return w
}
func (p *parser) xstring() (r string) {
if p.take(`"`) {
esc := false
r := ""
for i, c := range p.orig[p.o:] {
if c == '\\' {
esc = true
} else if c == '\x00' || c == '\r' || c == '\n' {
p.xerrorf("invalid nul, cr or lf in string")
} else if esc {
if c == '\\' || c == '"' {
r += string(c)
esc = false
} else {
p.xerrorf("invalid escape char %c", c)
}
} else if c == '"' {
p.o += i + 1
return r
} else {
r += string(c)
}
}
p.xerrorf("missing closing dquote in string")
}
size, sync := p.xliteralSize(100*1024, false)
s := p.conn.xreadliteral(size, sync)
line := p.conn.readline(false)
p.orig, p.upper, p.o = line, toUpper(line), 0
return s
}
func (p *parser) xnil() {
p.xtake("NIL")
}
// Returns NIL as empty string.
func (p *parser) xnilString() string {
if p.take("NIL") {
return ""
}
return p.xstring()
}
func (p *parser) xastring() string {
if p.hasPrefix(`"`) || p.hasPrefix("{") || p.hasPrefix("~{") {
return p.xstring()
}
return p.xtakechars(astringChar, "astring")
}
func contains(s string, c rune) bool {
for _, x := range s {
if x == c {
return true
}
}
return false
}
func (p *parser) xtag() string {
p.xnonempty()
for i, c := range p.orig[p.o:] {
if c == '+' || !contains(astringChar, c) {
return p.xtake1n(i, "tag")
}
}
return p.xtakeall()
}
func (p *parser) xcommand() string {
for i, c := range p.upper[p.o:] {
if !(c >= 'A' && c <= 'Z' || c == ' ' && p.upper[p.o:p.o+i] == "UID") {
return p.xtake1n(i, "command")
}
}
return p.xtakeall()
}
func (p *parser) remainder() string {
return p.orig[p.o:]
}
// ../rfc/9051:6565
func (p *parser) xflag() string {
w, _ := p.takelist(`\`, "$")
s := w + p.xatom()
if s[0] == '\\' {
switch strings.ToLower(s) {
case `\answered`, `\flagged`, `\deleted`, `\seen`, `\draft`:
default:
p.xerrorf("unknown system flag %s", s)
}
}
return s
}
func (p *parser) xflagList() (l []string) {
p.xtake("(")
if !p.hasPrefix(")") {
l = append(l, p.xflag())
}
for !p.take(")") {
p.xspace()
l = append(l, p.xflag())
}
return
}
func (p *parser) xatom() string {
return p.xtakechars(atomChar, "atom")
}
func (p *parser) xmailbox() string {
s := p.xastring()
// UTF-7 is deprecated in IMAP4rev2. IMAP4rev1 does not fully forbid
// UTF-8 returned in mailbox names. We'll do our best by attempting to
// decode utf-7. But if that doesn't work, we'll just use the original
// string.
// ../rfc/3501:964
if !p.conn.enabled[capIMAP4rev2] {
ns, err := utf7decode(s)
if err != nil {
p.conn.log.Infox("decoding utf7 or mailbox name", err, mlog.Field("name", s))
} else {
s = ns
}
}
return s
}
// ../rfc/9051:6605
func (p *parser) xlistMailbox() string {
if p.hasPrefix(`"`) || p.hasPrefix("{") {
return p.xstring()
}
return p.xtakechars(atomChar+listWildcards+respSpecials, "list-char")
}
// ../rfc/9051:6707 ../rfc/9051:6848 ../rfc/5258:1095 ../rfc/5258:1169 ../rfc/5258:1196
func (p *parser) xmboxOrPat() ([]string, bool) {
if !p.take("(") {
return []string{p.xlistMailbox()}, false
}
l := []string{p.xlistMailbox()}
for !p.take(")") {
p.xspace()
l = append(l, p.xlistMailbox())
}
return l, true
}
// ../rfc/9051:7056, RECENT ../rfc/3501:5047, APPENDLIMIT ../rfc/7889:252, HIGHESTMODSEQ ../rfc/7162:2452
func (p *parser) xstatusAtt() string {
w := p.xtakelist("MESSAGES", "UIDNEXT", "UIDVALIDITY", "UNSEEN", "DELETED", "SIZE", "RECENT", "APPENDLIMIT", "HIGHESTMODSEQ")
if w == "HIGHESTMODSEQ" {
// HIGHESTMODSEQ is a CONDSTORE-enabling parameter. ../rfc/7162:375
p.conn.enabled[capCondstore] = true
}
return w
}
// ../rfc/9051:7133 ../rfc/9051:7034
func (p *parser) xnumSet0(allowStar, allowSearch bool) (r numSet) {
defer p.context("numSet")()
if allowSearch && p.take("$") {
return numSet{searchResult: true}
}
r.ranges = append(r.ranges, p.xnumRange0(allowStar))
for p.take(",") {
r.ranges = append(r.ranges, p.xnumRange0(allowStar))
}
return r
}
func (p *parser) xnumSet() (r numSet) {
return p.xnumSet0(true, true)
}
// parse numRange, which can be just a setNumber.
func (p *parser) xnumRange0(allowStar bool) (r numRange) {
if allowStar && p.take("*") {
r.first.star = true
} else {
r.first.number = p.xnznumber()
}
if p.take(":") {
r.last = &setNumber{}
if allowStar && p.take("*") {
r.last.star = true
} else {
r.last.number = p.xnznumber()
}
}
return
}
// ../rfc/9051:6989 ../rfc/3501:4977
func (p *parser) xsectionMsgtext() (r *sectionMsgtext) {
defer p.context("sectionMsgtext")()
msgtextWords := []string{"HEADER.FIELDS.NOT", "HEADER.FIELDS", "HEADER", "TEXT"}
w := p.xtakelist(msgtextWords...)
r = &sectionMsgtext{s: w}
if strings.HasPrefix(w, "HEADER.FIELDS") {
p.xspace()
p.xtake("(")
r.headers = append(r.headers, textproto.CanonicalMIMEHeaderKey(p.xastring()))
for {
if p.take(")") {
break
}
p.xspace()
r.headers = append(r.headers, textproto.CanonicalMIMEHeaderKey(p.xastring()))
}
}
return
}
// ../rfc/9051:6999 ../rfc/3501:4991
func (p *parser) xsectionSpec() (r *sectionSpec) {
defer p.context("parseSectionSpec")()
n, ok := p.nznumber()
if !ok {
return &sectionSpec{msgtext: p.xsectionMsgtext()}
}
defer p.context("part...")()
pt := &sectionPart{}
pt.part = append(pt.part, n)
for {
if !p.take(".") {
break
}
if n, ok := p.nznumber(); ok {
pt.part = append(pt.part, n)
continue
}
if p.take("MIME") {
pt.text = &sectionText{mime: true}
break
}
pt.text = &sectionText{msgtext: p.xsectionMsgtext()}
break
}
return &sectionSpec{part: pt}
}
// ../rfc/9051:6985 ../rfc/3501:4975
func (p *parser) xsection() *sectionSpec {
defer p.context("parseSection")()
p.xtake("[")
if p.take("]") {
return &sectionSpec{}
}
r := p.xsectionSpec()
p.xtake("]")
return r
}
// ../rfc/9051:6841
func (p *parser) xpartial() *partial {
p.xtake("<")
offset := p.xnumber()
p.xtake(".")
count := p.xnznumber()
p.xtake(">")
return &partial{offset, count}
}
// ../rfc/9051:6987
func (p *parser) xsectionBinary() (r []uint32) {
p.xtake("[")
if p.take("]") {
return nil
}
r = append(r, p.xnznumber())
for {
if !p.take(".") {
break
}
r = append(r, p.xnznumber())
}
p.xtake("]")
return r
}
var fetchAttWords = []string{
"ENVELOPE", "FLAGS", "INTERNALDATE", "RFC822.SIZE", "BODYSTRUCTURE", "UID", "BODY.PEEK", "BODY", "BINARY.PEEK", "BINARY.SIZE", "BINARY",
"RFC822.HEADER", "RFC822.TEXT", "RFC822", // older IMAP
"MODSEQ", // CONDSTORE extension.
}
// ../rfc/9051:6557 ../rfc/3501:4751 ../rfc/7162:2483
func (p *parser) xfetchAtt(isUID bool) (r fetchAtt) {
defer p.context("fetchAtt")()
f := p.xtakelist(fetchAttWords...)
r.peek = strings.HasSuffix(f, ".PEEK")
r.field = strings.TrimSuffix(f, ".PEEK")
switch r.field {
case "BODY":
if p.hasPrefix("[") {
r.section = p.xsection()
if p.hasPrefix("<") {
r.partial = p.xpartial()
}
}
case "BINARY":
r.sectionBinary = p.xsectionBinary()
if p.hasPrefix("<") {
r.partial = p.xpartial()
}
case "BINARY.SIZE":
r.sectionBinary = p.xsectionBinary()
case "MODSEQ":
// The RFC text mentions MODSEQ is only for FETCH, not UID FETCH, but the ABNF adds
// the attribute to the shared syntax, so UID FETCH also implements it.
// ../rfc/7162:905
// The wording about when to respond with a MODSEQ attribute could be more clear. ../rfc/7162:923 ../rfc/7162:388
// MODSEQ attribute is a CONDSTORE-enabling parameter. ../rfc/7162:377
p.conn.xensureCondstore(nil)
}
return
}
// ../rfc/9051:6553 ../rfc/3501:4748
func (p *parser) xfetchAtts(isUID bool) []fetchAtt {
defer p.context("fetchAtts")()
fields := func(l ...string) []fetchAtt {
r := make([]fetchAtt, len(l))
for i, s := range l {
r[i] = fetchAtt{field: s}
}
return r
}
if w, ok := p.takelist("ALL", "FAST", "FULL"); ok {
switch w {
case "ALL":
return fields("FLAGS", "INTERNALDATE", "RFC822.SIZE", "ENVELOPE")
case "FAST":
return fields("FLAGS", "INTERNALDATE", "RFC822.SIZE")
case "FULL":
return fields("FLAGS", "INTERNALDATE", "RFC822.SIZE", "ENVELOPE", "BODY")
}
panic("missing case")
}
if !p.hasPrefix("(") {
return []fetchAtt{p.xfetchAtt(isUID)}
}
l := []fetchAtt{}
p.xtake("(")
for {
l = append(l, p.xfetchAtt(isUID))
if !p.take(" ") {
break
}
}
p.xtake(")")
return l
}
func xint(p *parser, s string) int {
v, err := strconv.ParseInt(s, 10, 32)
if err != nil {
p.xerrorf("bad int %q: %v", s, err)
}
return int(v)
}
func (p *parser) digit() (string, bool) {
if p.empty() {
return "", false
}
c := p.orig[p.o]
if c < '0' || c > '9' {
return "", false
}
s := p.orig[p.o : p.o+1]
p.o++
return s, true
}
func (p *parser) xdigit() string {
s, ok := p.digit()
if !ok {
p.xerrorf("expected digit")
}
return s
}
// ../rfc/9051:6492 ../rfc/3501:4695
func (p *parser) xdateDayFixed() int {
if p.take(" ") {
return xint(p, p.xdigit())
}
return xint(p, p.xdigit()+p.xdigit())
}
var months = []string{"jan", "feb", "mar", "apr", "may", "jun", "jul", "aug", "sep", "oct", "nov", "dec"}
// ../rfc/9051:6495 ../rfc/3501:4698
func (p *parser) xdateMonth() time.Month {
s := strings.ToLower(p.xtaken(3))
for i, m := range months {
if m == s {
return time.Month(1 + i)
}
}
p.xerrorf("unknown month %q", s)
return 0
}
// ../rfc/9051:7120 ../rfc/3501:5067
func (p *parser) xtime() (int, int, int) {
h := xint(p, p.xtaken(2))
p.xtake(":")
m := xint(p, p.xtaken(2))
p.xtake(":")
s := xint(p, p.xtaken(2))
return h, m, s
}
// ../rfc/9051:7159 ../rfc/3501:5083
func (p *parser) xzone() (string, int) {
sign := p.xtakelist("+", "-")
s := p.xtaken(4)
v := xint(p, s)
seconds := (v/100)*3600 + (v%100)*60
if sign[0] == '-' {
seconds = -seconds
}
return sign + s, seconds
}
// ../rfc/9051:6502 ../rfc/3501:4713
func (p *parser) xdateTime() time.Time {
// DQUOTE date-day-fixed "-" date-month "-" date-year SP time SP zone DQUOTE
p.xtake(`"`)
day := p.xdateDayFixed()
p.xtake("-")
month := p.xdateMonth()
p.xtake("-")
year := xint(p, p.xtaken(4))
p.xspace()
hours, minutes, seconds := p.xtime()
p.xspace()
name, zoneSeconds := p.xzone()
p.xtake(`"`)
loc := time.FixedZone(name, zoneSeconds)
return time.Date(year, month, day, hours, minutes, seconds, 0, loc)
}
// ../rfc/9051:6655 ../rfc/7888:330 ../rfc/3501:4801
func (p *parser) xliteralSize(maxSize int64, lit8 bool) (size int64, sync bool) {
// todo: enforce that we get non-binary when ~ isn't present?
if lit8 {
p.take("~")
}
p.xtake("{")
size = p.xnumber64()
if maxSize > 0 && size > maxSize {
// ../rfc/7888:249
line := fmt.Sprintf("* BYE [ALERT] Max literal size %d is larger than allowed %d in this context", size, maxSize)
err := errors.New("literal too big")
panic(syntaxError{line, "TOOBIG", err.Error(), err})
}
sync = !p.take("+")
p.xtake("}")
p.xempty()
return size, sync
}
var searchKeyWords = []string{
"ALL", "ANSWERED", "BCC",
"BEFORE", "BODY",
"CC", "DELETED", "FLAGGED",
"FROM", "KEYWORD",
"NEW", "OLD", "ON", "RECENT", "SEEN",
"SINCE", "SUBJECT",
"TEXT", "TO",
"UNANSWERED", "UNDELETED", "UNFLAGGED",
"UNKEYWORD", "UNSEEN",
"DRAFT", "HEADER",
"LARGER", "NOT",
"OR",
"SENTBEFORE", "SENTON",
"SENTSINCE", "SMALLER",
"UID", "UNDRAFT",
"MODSEQ", // CONDSTORE extension.
}
// ../rfc/9051:6923 ../rfc/3501:4957, MODSEQ ../rfc/7162:2492
// differences: rfc 9051 removes NEW, OLD, RECENT and makes SMALLER and LARGER number64 instead of number.
func (p *parser) xsearchKey() *searchKey {
if p.take("(") {
sk := p.xsearchKey()
l := []searchKey{*sk}
for !p.take(")") {
p.xspace()
l = append(l, *p.xsearchKey())
}
return &searchKey{searchKeys: l}
}
w, ok := p.takelist(searchKeyWords...)
if !ok {
seqs := p.xnumSet()
return &searchKey{seqSet: &seqs}
}
sk := &searchKey{op: w}
switch sk.op {
case "ALL":
case "ANSWERED":
case "BCC":
p.xspace()
sk.astring = p.xastring()
case "BEFORE":
p.xspace()
sk.date = p.xdate()
case "BODY":
p.xspace()
sk.astring = p.xastring()
case "CC":
p.xspace()
sk.astring = p.xastring()
case "DELETED":
case "FLAGGED":
case "FROM":
p.xspace()
sk.astring = p.xastring()
case "KEYWORD":
p.xspace()
sk.atom = p.xatom()
case "NEW":
case "OLD":
case "ON":
p.xspace()
sk.date = p.xdate()
case "RECENT":
case "SEEN":
case "SINCE":
p.xspace()
sk.date = p.xdate()
case "SUBJECT":
p.xspace()
sk.astring = p.xastring()
case "TEXT":
p.xspace()
sk.astring = p.xastring()
case "TO":
p.xspace()
sk.astring = p.xastring()
case "UNANSWERED":
case "UNDELETED":
case "UNFLAGGED":
case "UNKEYWORD":
p.xspace()
sk.atom = p.xatom()
case "UNSEEN":
case "DRAFT":
case "HEADER":
p.xspace()
sk.headerField = p.xastring()
p.xspace()
sk.astring = p.xastring()
case "LARGER":
p.xspace()
sk.number = p.xnumber64()
case "NOT":
p.xspace()
sk.searchKey = p.xsearchKey()
case "OR":
p.xspace()
sk.searchKey = p.xsearchKey()
p.xspace()
sk.searchKey2 = p.xsearchKey()
case "SENTBEFORE":
p.xspace()
sk.date = p.xdate()
case "SENTON":
p.xspace()
sk.date = p.xdate()
case "SENTSINCE":
p.xspace()
sk.date = p.xdate()
case "SMALLER":
p.xspace()
sk.number = p.xnumber64()
case "UID":
p.xspace()
sk.uidSet = p.xnumSet()
case "UNDRAFT":
case "MODSEQ":
// ../rfc/7162:1045 ../rfc/7162:2499
p.xspace()
if p.take(`"`) {
// We don't do anything with this field, so parse and ignore.
p.xtake(`/FLAGS/`)
if p.take(`\`) {
p.xtake(`\`) // ../rfc/7162:1072
}
p.xatom()
p.xtake(`"`)
p.xspace()
p.xtakelist("PRIV", "SHARED", "ALL")
p.xspace()
}
v := p.xnumber64()
sk.clientModseq = &v
// MODSEQ is a CONDSTORE-enabling parameter. ../rfc/7162:377
p.conn.enabled[capCondstore] = true
default:
p.xerrorf("missing case for op %q", sk.op)
}
return sk
}
// hasModseq returns whether there is a modseq filter anywhere in the searchkey.
func (sk searchKey) hasModseq() bool {
if sk.clientModseq != nil {
return true
}
for _, e := range sk.searchKeys {
if e.hasModseq() {
return true
}
}
if sk.searchKey != nil && sk.searchKey.hasModseq() {
return true
}
if sk.searchKey2 != nil && sk.searchKey2.hasModseq() {
return true
}
return false
}
// ../rfc/9051:6489 ../rfc/3501:4692
func (p *parser) xdateDay() int {
d := p.xdigit()
if s, ok := p.digit(); ok {
d += s
}
return xint(p, d)
}
// ../rfc/9051:6487 ../rfc/3501:4690
func (p *parser) xdate() time.Time {
dquote := p.take(`"`)
day := p.xdateDay()
p.xtake("-")
mon := p.xdateMonth()
p.xtake("-")
year := xint(p, p.xtaken(4))
if dquote {
p.take(`"`)
}
return time.Date(year, mon, day, 0, 0, 0, 0, time.UTC)
}