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130 lines
3 KiB
Go
130 lines
3 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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"strings"
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)
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/*
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Rules for validation are subset of rules listed here:
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https://emailregex.com/email-validation-summary/
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*/
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// Valid checks whether ths string is valid as a email address as defined by
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// RFC 5321.
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func Valid(addr string) bool {
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if len(addr) > 320 { // RFC 3696 says it's 320, not 255.
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return false
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}
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mbox, domain, err := Split(addr)
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if err != nil {
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return false
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}
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// The only case where this can be true is "postmaster".
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// So allow it.
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if domain == "" {
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return true
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}
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return ValidMailboxName(mbox) && ValidDomain(domain)
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}
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var validGraphic = map[rune]bool{
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'!': true, '#': true,
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'$': true, '%': true,
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'&': true, '\'': true,
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'*': true, '+': true,
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'-': true, '/': true,
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'=': true, '?': true,
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'^': true, '_': true,
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'`': true, '{': true,
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'|': true, '}': true,
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'~': true,
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}
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// ValidMailboxName checks whether the specified string is a valid mailbox-name
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// element of e-mail address (left part of it, before at-sign).
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func ValidMailboxName(mbox string) bool {
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if strings.HasPrefix(mbox, `"`) {
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raw, err := UnquoteMbox(mbox)
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if err != nil {
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return false
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}
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// Inside quotes, any ASCII graphic and space is allowed.
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// Additionally, RFC 6531 extends that to allow any Unicode (UTF-8).
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for _, ch := range raw {
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if ch < ' ' || ch == 0x7F /* DEL */ {
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// ASCII control characters.
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return false
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}
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}
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return true
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}
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// Without quotes, limited set of ASCII graphics is allowed + ASCII
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// alphanumeric characters.
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// RFC 6531 extends that to allow any Unicode (UTF-8).
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for _, ch := range mbox {
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if validGraphic[ch] {
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continue
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}
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if ch >= '0' && ch <= '9' {
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continue
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}
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if ch >= 'A' && ch <= 'Z' {
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continue
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}
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if ch >= 'a' && ch <= 'z' {
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continue
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}
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if ch > 0x7F { // Unicode
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continue
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}
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return false
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}
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return true
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}
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// ValidDomain checks whether the specified string is a valid DNS domain.
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func ValidDomain(domain string) bool {
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if len(domain) > 255 {
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return false
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}
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if strings.HasPrefix(domain, ".") || strings.HasSuffix(domain, ".") {
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return false
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}
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if strings.Contains(domain, "..") {
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return false
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}
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labels := strings.Split(domain, ".")
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for _, label := range labels {
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if len(label) > 64 {
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return false
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}
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}
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return true
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}
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