mirror of
https://github.com/ProtonMail/proton-bridge.git
synced 2025-12-10 12:46:46 +00:00
105 lines
2.4 KiB
Go
105 lines
2.4 KiB
Go
// Copyright (c) 2021 Proton Technologies AG
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//
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// This file is part of ProtonMail Bridge.
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//
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// ProtonMail Bridge 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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//
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// ProtonMail Bridge 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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//
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// You should have received a copy of the GNU General Public License
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// along with ProtonMail Bridge. If not, see <https://www.gnu.org/licenses/>.
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package imap
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import (
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"bufio"
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"bytes"
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"io"
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"strings"
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"github.com/emersion/go-imap"
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"github.com/pkg/errors"
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)
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func filterHeader(header []byte, section *imap.BodySectionName) []byte {
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// Empty section.Fields means BODY[HEADER] was requested so we should return the full header.
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if len(section.Fields) == 0 {
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return header
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}
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fieldMap := make(map[string]struct{})
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for _, field := range section.Fields {
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fieldMap[strings.ToLower(field)] = struct{}{}
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}
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return filterHeaderLines(header, func(field string) bool {
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_, ok := fieldMap[strings.ToLower(field)]
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if section.NotFields {
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ok = !ok
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}
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return ok
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})
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}
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func filterHeaderLines(header []byte, wantField func(string) bool) []byte {
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var res []byte
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for _, line := range headerLines(header) {
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if len(bytes.TrimSpace(line)) == 0 {
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res = append(res, line...)
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} else {
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split := bytes.SplitN(line, []byte(": "), 2)
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if len(split) != 2 {
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continue
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}
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if wantField(string(bytes.ToLower(split[0]))) {
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res = append(res, line...)
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}
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}
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}
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return res
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}
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// NOTE: This sucks because we trim and split stuff here already, only to do it again when we use this function!
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func headerLines(header []byte) [][]byte {
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var lines [][]byte
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r := bufio.NewReader(bytes.NewReader(header))
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for {
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b, err := r.ReadBytes('\n')
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if err != nil {
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if err != io.EOF {
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panic(errors.Wrap(err, "failed to read header line"))
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}
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break
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}
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switch {
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case len(bytes.TrimSpace(b)) == 0:
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lines = append(lines, b)
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case len(bytes.SplitN(b, []byte(": "), 2)) != 2:
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lines[len(lines)-1] = append(lines[len(lines)-1], b...)
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default:
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lines = append(lines, b)
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}
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}
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return lines
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}
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