root
138 lines
5.5 KiB
Go
138 lines
5.5 KiB
Go
// Copyright 2026 The Gitea Authors. All rights reserved.
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// SPDX-License-Identifier: MIT
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package incoming
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import (
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"regexp"
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"strings"
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"sync"
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"gitea.dev/modules/util"
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)
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const (
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yearToken = `\b\d{4}\b` // 4-digit year
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timeToken = `\b\d{1,2}[:.]\d{2}\b` // HH:MM or HH.MM
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// "wrote" verbs ending an attribution line; CJK ones are matched without a
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// preceding word-separator since those scripts don't space their words
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wroteVerbs = `wrote|writes|schrieb|skrev|napisał|escreveu|escribió|написал|пише|a écrit`
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cjkWroteVerbs = `写道|寫道|書きました|작성`
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// device names anchoring CJK mobile signatures, so prose isn't mistaken for one
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cjkDevice = `iphone|ipad|ipod|android|galaxy|手机|手機|平板`
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)
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// forwarded-mail header fields across the common mail clients/locales. headerFromFields
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// (the "From"-equivalents) must begin a block; headerFields is the full set allowed to
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// follow. Matched as a prefix by headerLine, so adding a locale is a one-line change.
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var (
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headerFromFields = []string{
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"from", "fra", "de", "von", "da", "van", "från", "expéditeur",
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"发件人", "寄件者", "差出人", "보낸사람",
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}
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headerFields = append([]string{
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"to", "cc", "bcc", "sent", "date", "subject", "reply-to",
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"til", "emne", "an", "betreff", "gesendet", "para", "assunto", "asunto",
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"risposta", "inviato", "oggetto", "destinataire", "objet", "répondre à",
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"aan", "onderwerp", "beantwoorden", "skickat", "till", "ämne",
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"收件人", "主题", "主旨", "主題", "收件者", "抄送", "日期", "宛先", "件名", "받는사람", "제목",
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}, headerFromFields...)
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)
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// patterns are compiled on first use so the incoming-mail feature adds nothing to startup.
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var patterns = sync.OnceValue(func() (ret struct {
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signature, attribution, separator *regexp.Regexp
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},
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) {
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// "-- " delimiter and common mobile footers with frequent localizations. The CJK
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// forms require a device name so ordinary prose like "发自我的内心" or "会議から送信"
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// is not mistaken for a signature.
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ret.signature = regexp.MustCompile(`(?i)^(--|__|—` +
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`|sent (from|via|with) .+|get outlook for .+` +
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`|envoyé depuis mon .+|sendt fra min .+|von meinem .+|verzonden (met|vanaf) .+` +
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`|(發|发)自我的.*(` + cjkDevice + `).*` +
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`|.*(` + cjkDevice + `).*(から送信|에서 보냄|傳送|发送))$`)
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// attribution introducing quoted history: a line ending in a "wrote:" verb
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// (Latin/Cyrillic or CJK), a "Name <email> wrote" line, a lead word directly
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// followed by a day number or weekday plus a year and a time, or an ISO-date-led
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// line. The date phrasing, trailing colon and the email before the verb guard
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// against prose (so "On the 2024 roadmap … at 10:00" is not an attribution).
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ret.attribution = regexp.MustCompile(`(?i)^>*\s*(` +
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`.*[\s">'](` + wroteVerbs + `)\s*[:：]` +
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`|.*(` + cjkWroteVerbs + `)\s*[:：]` +
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`|.*<\S+@\S+>\s+(` + wroteVerbs + `)\b.*` +
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`|(on|at|le|am|el|em|den|il|op|dnia|w dniu)\b[\s,]*(\d|(?:mon|tue|wed|thu|fri|sat|sun)\b).*` + yearToken + `.*` + timeToken + `.*` +
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`|\d{4}-\d{2}-\d{2}\b.*` + timeToken + `.*` +
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`)$`)
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// a dash/underscore rule line, or text fenced by dashes such as
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// "-------- Original Message --------" or "-----Mensaje original-----"
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ret.separator = regexp.MustCompile(`(?i)^\s*\*?\s*([-_]{5,}|-{2,}.+-{2,}|original message|forwarded message)\s*\*?\s*$`)
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return ret
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})
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// extractReply returns the user-written part of a plain-text email body, dropping
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// quoted history, the reply attribution, signatures and forwarded headers. It is a
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// slim, dependency-free reimplementation based on github.com/dimiro1/reply (MIT),
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// covering the common mail-client formats and languages; bottom posting and
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// forwarded bodies are not handled.
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func extractReply(text string) string {
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p := patterns()
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lines := strings.Split(util.NormalizeStringEOL(text), "\n")
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// cut at the first line that begins quoted history, a signature or a header block
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for i := range lines {
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trimmed := strings.TrimSpace(lines[i])
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if p.signature.MatchString(trimmed) || p.attribution.MatchString(trimmed) ||
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p.separator.MatchString(trimmed) || headerBlock(trimmed, lines[i+1:]) {
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lines = lines[:i]
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break
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}
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}
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// drop the trailing block of quoted/blank lines, unless the whole body is quoted
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end := len(lines)
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for end > 0 {
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// "ᐧ" is the trailing marker some mobile clients (Mailbox) append
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if t := strings.TrimSpace(lines[end-1]); t != "" && t != "ᐧ" && !strings.HasPrefix(t, ">") {
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break
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}
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end--
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}
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if end > 0 {
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lines = lines[:end]
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}
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return strings.TrimSpace(strings.Join(lines, "\n"))
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}
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// headerBlock reports whether a forwarded-mail header block starts here: the
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// (already-trimmed) first line is a "From" field and the next non-blank line is
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// another field, so a lone "Subject:" sentence is not a boundary.
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func headerBlock(first string, rest []string) bool {
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if !headerLine(first, headerFromFields) {
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return false
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}
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for _, next := range rest {
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if t := strings.TrimSpace(next); t != "" {
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return headerLine(t, headerFields)
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}
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}
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return false
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}
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// headerLine reports whether the already-trimmed line is a "Field:" header for one
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// of fields. An ASCII colon must be followed by a space so prose like "To:do this"
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// is ignored; the CJK fullwidth colon "：" needs no space.
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func headerLine(line string, fields []string) bool {
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lower := strings.ToLower(line)
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for _, field := range fields {
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if rest, ok := strings.CutPrefix(lower, field); ok &&
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(strings.HasPrefix(rest, ": ") || strings.HasPrefix(rest, "：")) {
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return true
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}
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}
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return false
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}
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