aboutsummaryrefslogtreecommitdiff
path: root/worker/lib/parse.go
blob: c3a43ca5136298eb1bc6431f93ce3903142f7b6a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
package lib

import (
	"bytes"
	"encoding/base64"
	"fmt"
	"io"
	"mime/quotedprintable"
	"strings"

	"git.sr.ht/~sircmpwn/aerc/models"
	"github.com/emersion/go-message"
	_ "github.com/emersion/go-message/charset"
	"github.com/emersion/go-message/mail"
)

func FetchEntityPartReader(e *message.Entity, index []int) (io.Reader, error) {
	if len(index) < 1 {
		return nil, fmt.Errorf("no part to read")
	}
	if mpr := e.MultipartReader(); mpr != nil {
		idx := 0
		for {
			idx++
			part, err := mpr.NextPart()
			if err != nil {
				return nil, err
			}
			if idx == index[0] {
				rest := index[1:]
				if len(rest) < 1 {
					return fetchEntityReader(part)
				}
				return FetchEntityPartReader(part, index[1:])
			}
		}
	}
	if index[0] != 1 {
		return nil, fmt.Errorf("cannont return non-first part of non-multipart")
	}
	return fetchEntityReader(e)
}

// fetchEntityReader makes an io.Reader for the given entity. Since the
// go-message package decodes the body for us, and the UI expects to deal with
// a reader whose bytes are encoded with the part's encoding, we are in the
// interesting position of needing to re-encode the reader before sending it
// off to the UI layer.
//
// TODO: probably change the UI to expect an already-decoded reader and decode
// in the IMAP worker.
func fetchEntityReader(e *message.Entity) (io.Reader, error) {
	enc := e.Header.Get("content-transfer-encoding")
	var buf bytes.Buffer

	// base64
	if strings.EqualFold(enc, "base64") {
		wc := base64.NewEncoder(base64.StdEncoding, &buf)
		defer wc.Close()
		if _, err := io.Copy(wc, e.Body); err != nil {
			return nil, fmt.Errorf("could not base64 encode: %v", err)
		}
		return &buf, nil
	}

	// quoted-printable
	if strings.EqualFold(enc, "quoted-printable") {
		wc := quotedprintable.NewWriter(&buf)
		defer wc.Close()
		if _, err := io.Copy(wc, e.Body); err != nil {
			return nil, fmt.Errorf("could not quoted-printable encode: %v", err)
		}
		return &buf, nil
	}

	// other general encoding
	if _, err := io.Copy(&buf, e.Body); err != nil {
		return nil, err
	}

	return &buf, nil
}

// split a MIME type into its major and minor parts
func splitMIME(m string) (string, string) {
	parts := strings.Split(m, "/")
	if len(parts) != 2 {
		return parts[0], ""
	}
	return parts[0], parts[1]
}

func parseEntityStructure(e *message.Entity) (*models.BodyStructure, error) {
	var body models.BodyStructure
	contentType, ctParams, err := e.Header.ContentType()
	if err != nil {
		return nil, fmt.Errorf("could not parse content type: %v", err)
	}
	mimeType, mimeSubType := splitMIME(contentType)
	body.MIMEType = mimeType
	body.MIMESubType = mimeSubType
	body.Params = ctParams
	body.Description = e.Header.Get("content-description")
	body.Encoding = e.Header.Get("content-transfer-encoding")
	if cd := e.Header.Get("content-disposition"); cd != "" {
		contentDisposition, cdParams, err := e.Header.ContentDisposition()
		if err != nil {
			return nil, fmt.Errorf("could not parse content disposition: %v", err)
		}
		body.Disposition = contentDisposition
		body.DispositionParams = cdParams
	}
	body.Parts = []*models.BodyStructure{}
	if mpr := e.MultipartReader(); mpr != nil {
		for {
			part, err := mpr.NextPart()
			if err == io.EOF {
				return &body, nil
			} else if err != nil {
				return nil, err
			}
			ps, err := parseEntityStructure(part)
			if err != nil {
				return nil, fmt.Errorf("could not parse child entity structure: %v", err)
			}
			body.Parts = append(body.Parts, ps)
		}
	}
	return &body, nil
}

func parseEnvelope(h *mail.Header) (*models.Envelope, error) {
	date, err := h.Date()
	if err != nil {
		return nil, fmt.Errorf("could not parse date header: %v", err)
	}
	from, err := parseAddressList(h, "from")
	if err != nil {
		return nil, fmt.Errorf("could not read from address: %v", err)
	}
	to, err := parseAddressList(h, "to")
	if err != nil {
		return nil, fmt.Errorf("could not read to address: %v", err)
	}
	cc, err := parseAddressList(h, "cc")
	if err != nil {
		return nil, fmt.Errorf("could not read cc address: %v", err)
	}
	bcc, err := parseAddressList(h, "bcc")
	if err != nil {
		return nil, fmt.Errorf("could not read bcc address: %v", err)
	}
	replyTo, err := parseAddressList(h, "reply-to")
	if err != nil {
		return nil, fmt.Errorf("could not read reply-to address: %v", err)
	}
	subj, err := h.Subject()
	if err != nil {
		return nil, fmt.Errorf("could not read subject: %v", err)
	}
	msgID, err := h.Text("message-id")
	if err != nil {
		return nil, fmt.Errorf("could not read message id: %v", err)
	}
	return &models.Envelope{
		Date:      date,
		Subject:   subj,
		MessageId: msgID,
		From:      from,
		ReplyTo:   replyTo,
		To:        to,
		Cc:        cc,
		Bcc:       bcc,
	}, nil
}

func parseAddressList(h *mail.Header, key string) ([]*models.Address, error) {
	var converted []*models.Address
	addrs, err := h.AddressList(key)
	if err != nil {
		if hdr, err := h.Text(key); err != nil && strings.Contains(hdr, "@") {
			return []*models.Address{&models.Address{
				Name: hdr,
			}}, nil
		}
		return nil, err
	}
	for _, addr := range addrs {
		parts := strings.Split(addr.Address, "@")
		var mbox, host string
		if len(parts) > 1 {
			mbox = strings.Join(parts[0:len(parts)-1], "@")
			host = parts[len(parts)-1]
		} else {
			mbox = addr.Address
		}
		converted = append(converted, &models.Address{
			Name:    addr.Name,
			Mailbox: mbox,
			Host:    host,
		})
	}
	return converted, nil
}

// RawMessage is an interface that describes a raw message
type RawMessage interface {
	NewReader() (io.Reader, error)
	ModelFlags() ([]models.Flag, error)
	UID() uint32
}

// MessageInfo populates a models.MessageInfo struct for the message.
// based on the reader returned by NewReader
func MessageInfo(raw RawMessage) (*models.MessageInfo, error) {
	r, err := raw.NewReader()
	if err != nil {
		return nil, err
	}
	msg, err := message.Read(r)
	if err != nil {
		return nil, fmt.Errorf("could not read message: %v", err)
	}
	bs, err := parseEntityStructure(msg)
	if err != nil {
		return nil, fmt.Errorf("could not get structure: %v", err)
	}
	env, err := parseEnvelope(&mail.Header{msg.Header})
	if err != nil {
		return nil, fmt.Errorf("could not get envelope: %v", err)
	}
	flags, err := raw.ModelFlags()
	if err != nil {
		return nil, err
	}
	return &models.MessageInfo{
		BodyStructure: bs,
		Envelope:      env,
		Flags:         flags,
		InternalDate:  env.Date,
		RFC822Headers: &mail.Header{msg.Header},
		Size:          0,
		Uid:           raw.UID(),
	}, nil
}