133 lines
3.4 KiB
Go
133 lines
3.4 KiB
Go
/*
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Maddy Mail Server - Composable all-in-one email server.
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Copyright © 2019-2020 Max Mazurov <fox.cpp@disroot.org>, Maddy Mail Server contributors
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>.
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*/
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package address
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import (
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"errors"
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"strings"
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)
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// Split splits a email address (as defined by RFC 5321 as a forward-path
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// token) into local part (mailbox) and domain.
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//
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// Note that definition of the forward-path token includes the special
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// postmaster address without the domain part. Split will return domain == ""
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// in this case.
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//
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// Split does almost no sanity checks on the input and is intentionally naive.
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// If this is a concern, ValidMailbox and ValidDomain should be used on the
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// output.
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func Split(addr string) (mailbox, domain string, err error) {
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if strings.EqualFold(addr, "postmaster") {
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return addr, "", nil
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}
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indx := strings.LastIndexByte(addr, '@')
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if indx == -1 {
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return "", "", errors.New("address: missing at-sign")
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}
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mailbox = addr[:indx]
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domain = addr[indx+1:]
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if mailbox == "" {
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return "", "", errors.New("address: empty local-part")
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}
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if domain == "" {
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return "", "", errors.New("address: empty domain")
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}
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return
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}
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// UnquoteMbox undoes escaping and quoting of the local-part. That is, for
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// local-part `"test\" @ test"` it will return `test" @test`.
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func UnquoteMbox(mbox string) (string, error) {
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var (
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quoted bool
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escaped bool
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terminatedQuote bool
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mailboxB strings.Builder
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)
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for _, ch := range mbox {
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if terminatedQuote {
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return "", errors.New("address: closing quote should be right before at-sign")
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}
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switch ch {
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case '"':
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if !escaped {
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quoted = !quoted
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if !quoted {
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terminatedQuote = true
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}
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continue
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}
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case '\\':
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if !escaped {
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if !quoted {
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return "", errors.New("address: escapes are allowed only in quoted strings")
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}
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escaped = true
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continue
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}
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case '@':
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if !quoted {
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return "", errors.New("address: extra at-sign in non-quoted local-part")
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}
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}
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escaped = false
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mailboxB.WriteRune(ch)
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}
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if mailboxB.Len() == 0 {
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return "", errors.New("address: empty local part")
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}
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return mailboxB.String(), nil
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}
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// "specials" from RFC5322 grammar with dot removed (it is defined in grammar separately, for some reason)
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var mboxSpecial = map[rune]struct{}{
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'(': {}, ')': {}, '<': {}, '>': {},
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'[': {}, ']': {}, ':': {}, ';': {},
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'@': {}, '\\': {}, ',': {},
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'"': {}, ' ': {},
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}
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func QuoteMbox(mbox string) string {
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var mailboxEsc strings.Builder
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mailboxEsc.Grow(len(mbox))
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quoted := false
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for _, ch := range mbox {
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if _, ok := mboxSpecial[ch]; ok {
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if ch == '\\' || ch == '"' {
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mailboxEsc.WriteRune('\\')
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}
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mailboxEsc.WriteRune(ch)
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quoted = true
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} else {
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mailboxEsc.WriteRune(ch)
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}
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}
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if quoted {
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return `"` + mailboxEsc.String() + `"`
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}
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return mbox
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}
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