459 lines
12 KiB
Go
459 lines
12 KiB
Go
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package parsemail
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import (
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"bytes"
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"encoding/base64"
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"fmt"
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"io"
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"io/ioutil"
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"mime"
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"mime/multipart"
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"net/mail"
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"strings"
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"time"
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)
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const contentTypeMultipartMixed = "multipart/mixed"
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const contentTypeMultipartAlternative = "multipart/alternative"
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const contentTypeMultipartRelated = "multipart/related"
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const contentTypeTextHtml = "text/html"
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const contentTypeTextPlain = "text/plain"
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// Parse an email message read from io.Reader into parsemail.Email struct
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func Parse(r io.Reader) (email Email, err error) {
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msg, err := mail.ReadMessage(r)
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if err != nil {
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return
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}
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email, err = createEmailFromHeader(msg.Header)
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if err != nil {
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return
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}
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contentType, params, err := parseContentType(msg.Header.Get("Content-Type"))
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if err != nil {
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return
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}
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switch contentType {
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case contentTypeMultipartMixed:
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email.TextBody, email.HTMLBody, email.Attachments, email.EmbeddedFiles, err = parseMultipartMixed(msg.Body, params["boundary"])
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case contentTypeMultipartAlternative:
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email.TextBody, email.HTMLBody, email.EmbeddedFiles, err = parseMultipartAlternative(msg.Body, params["boundary"])
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case contentTypeTextPlain:
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message, _ := ioutil.ReadAll(msg.Body)
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email.TextBody = strings.TrimSuffix(string(message[:]), "\n")
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case contentTypeTextHtml:
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message, _ := ioutil.ReadAll(msg.Body)
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email.HTMLBody = strings.TrimSuffix(string(message[:]), "\n")
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default:
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err = fmt.Errorf("Unknown top level mime type: %s", contentType)
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}
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return
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}
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func createEmailFromHeader(header mail.Header) (email Email, err error) {
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hp := headerParser{header: &header}
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email.Subject = decodeMimeSentence(header.Get("Subject"))
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email.From = hp.parseAddressList(header.Get("From"))
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email.Sender = hp.parseAddress(header.Get("Sender"))
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email.ReplyTo = hp.parseAddressList(header.Get("Reply-To"))
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email.To = hp.parseAddressList(header.Get("To"))
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email.Cc = hp.parseAddressList(header.Get("Cc"))
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email.Bcc = hp.parseAddressList(header.Get("Bcc"))
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email.Date = hp.parseTime(header.Get("Date"))
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email.ResentFrom = hp.parseAddressList(header.Get("Resent-From"))
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email.ResentSender = hp.parseAddress(header.Get("Resent-Sender"))
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email.ResentTo = hp.parseAddressList(header.Get("Resent-To"))
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email.ResentCc = hp.parseAddressList(header.Get("Resent-Cc"))
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email.ResentBcc = hp.parseAddressList(header.Get("Resent-Bcc"))
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email.ResentMessageID = hp.parseMessageId(header.Get("Resent-Message-ID"))
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email.MessageID = hp.parseMessageId(header.Get("Message-ID"))
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email.InReplyTo = hp.parseMessageIdList(header.Get("In-Reply-To"))
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email.References = hp.parseMessageIdList(header.Get("References"))
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email.ResentDate = hp.parseTime(header.Get("Resent-Date"))
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if hp.err != nil {
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err = hp.err
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return
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}
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//decode whole header for easier access to extra fields
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//todo: should we decode? aren't only standard fields mime encoded?
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email.Header, err = decodeHeaderMime(header)
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if err != nil {
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return
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}
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return
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}
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func parseContentType(contentTypeHeader string) (contentType string, params map[string]string, err error) {
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if contentTypeHeader == "" {
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contentType = contentTypeTextPlain
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return
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}
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return mime.ParseMediaType(contentTypeHeader)
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}
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func parseMultipartRelated(msg io.Reader, boundary string) (textBody, htmlBody string, embeddedFiles []EmbeddedFile, err error) {
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pmr := multipart.NewReader(msg, boundary)
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for {
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part, err := pmr.NextPart()
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if err == io.EOF {
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break
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} else if err != nil {
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return textBody, htmlBody, embeddedFiles, err
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}
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contentType, params, err := mime.ParseMediaType(part.Header.Get("Content-Type"))
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if err != nil {
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return textBody, htmlBody, embeddedFiles, err
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}
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switch contentType {
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case contentTypeTextPlain:
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ppContent, err := ioutil.ReadAll(part)
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if err != nil {
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return textBody, htmlBody, embeddedFiles, err
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}
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textBody += strings.TrimSuffix(string(ppContent[:]), "\n")
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case contentTypeTextHtml:
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ppContent, err := ioutil.ReadAll(part)
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if err != nil {
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return textBody, htmlBody, embeddedFiles, err
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}
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htmlBody += strings.TrimSuffix(string(ppContent[:]), "\n")
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case contentTypeMultipartAlternative:
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tb, hb, ef, err := parseMultipartAlternative(part, params["boundary"])
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if err != nil {
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return textBody, htmlBody, embeddedFiles, err
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}
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htmlBody += hb
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textBody += tb
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embeddedFiles = append(embeddedFiles, ef...)
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default:
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if isEmbeddedFile(part) {
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ef, err := decodeEmbeddedFile(part)
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if err != nil {
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return textBody, htmlBody, embeddedFiles, err
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}
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embeddedFiles = append(embeddedFiles, ef)
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} else {
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return textBody, htmlBody, embeddedFiles, fmt.Errorf("Can't process multipart/related inner mime type: %s", contentType)
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}
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}
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}
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return textBody, htmlBody, embeddedFiles, err
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}
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func parseMultipartAlternative(msg io.Reader, boundary string) (textBody, htmlBody string, embeddedFiles []EmbeddedFile, err error) {
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pmr := multipart.NewReader(msg, boundary)
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for {
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part, err := pmr.NextPart()
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if err == io.EOF {
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break
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} else if err != nil {
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return textBody, htmlBody, embeddedFiles, err
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}
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contentType, params, err := mime.ParseMediaType(part.Header.Get("Content-Type"))
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if err != nil {
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return textBody, htmlBody, embeddedFiles, err
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}
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switch contentType {
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case contentTypeTextPlain:
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ppContent, err := ioutil.ReadAll(part)
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if err != nil {
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return textBody, htmlBody, embeddedFiles, err
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}
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textBody += strings.TrimSuffix(string(ppContent[:]), "\n")
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case contentTypeTextHtml:
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ppContent, err := ioutil.ReadAll(part)
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if err != nil {
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return textBody, htmlBody, embeddedFiles, err
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}
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htmlBody += strings.TrimSuffix(string(ppContent[:]), "\n")
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case contentTypeMultipartRelated:
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tb, hb, ef, err := parseMultipartRelated(part, params["boundary"])
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if err != nil {
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return textBody, htmlBody, embeddedFiles, err
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}
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htmlBody += hb
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textBody += tb
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embeddedFiles = append(embeddedFiles, ef...)
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default:
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if isEmbeddedFile(part) {
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ef, err := decodeEmbeddedFile(part)
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if err != nil {
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return textBody, htmlBody, embeddedFiles, err
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}
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embeddedFiles = append(embeddedFiles, ef)
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} else {
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return textBody, htmlBody, embeddedFiles, fmt.Errorf("Can't process multipart/alternative inner mime type: %s", contentType)
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}
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}
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}
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return textBody, htmlBody, embeddedFiles, err
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}
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func parseMultipartMixed(msg io.Reader, boundary string) (textBody, htmlBody string, attachments []Attachment, embeddedFiles []EmbeddedFile, err error) {
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mr := multipart.NewReader(msg, boundary)
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for {
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part, err := mr.NextPart()
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if err == io.EOF {
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break
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} else if err != nil {
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return textBody, htmlBody, attachments, embeddedFiles, err
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}
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contentType, params, err := mime.ParseMediaType(part.Header.Get("Content-Type"))
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if err != nil {
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return textBody, htmlBody, attachments, embeddedFiles, err
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}
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if contentType == contentTypeMultipartAlternative {
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textBody, htmlBody, embeddedFiles, err = parseMultipartAlternative(part, params["boundary"])
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if err != nil {
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return textBody, htmlBody, attachments, embeddedFiles, err
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}
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} else if contentType == contentTypeMultipartRelated {
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textBody, htmlBody, embeddedFiles, err = parseMultipartRelated(part, params["boundary"])
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if err != nil {
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return textBody, htmlBody, attachments, embeddedFiles, err
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}
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} else if isAttachment(part) {
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at, err := decodeAttachment(part)
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if err != nil {
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return textBody, htmlBody, attachments, embeddedFiles, err
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}
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attachments = append(attachments, at)
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} else {
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return textBody, htmlBody, attachments, embeddedFiles, fmt.Errorf("Unknown multipart/mixed nested mime type: %s", contentType)
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}
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}
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return textBody, htmlBody, attachments, embeddedFiles, err
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}
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func decodeMimeSentence(s string) string {
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result := []string{}
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ss := strings.Split(s, " ")
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for _, word := range ss {
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dec := new(mime.WordDecoder)
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w, err := dec.Decode(word)
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if err != nil {
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if len(result) == 0 {
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w = word
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} else {
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w = " " + word
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}
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}
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result = append(result, w)
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}
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return strings.Join(result, "")
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}
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func decodeHeaderMime(header mail.Header) (mail.Header, error) {
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parsedHeader := map[string][]string{}
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for headerName, headerData := range header {
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parsedHeaderData := []string{}
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for _, headerValue := range headerData {
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parsedHeaderData = append(parsedHeaderData, decodeMimeSentence(headerValue))
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}
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parsedHeader[headerName] = parsedHeaderData
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}
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return mail.Header(parsedHeader), nil
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}
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func decodePartData(part *multipart.Part) (io.Reader, error) {
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encoding := part.Header.Get("Content-Transfer-Encoding")
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if strings.EqualFold(encoding, "base64") {
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dr := base64.NewDecoder(base64.StdEncoding, part)
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dd, err := ioutil.ReadAll(dr)
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if err != nil {
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return nil, err
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}
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return bytes.NewReader(dd), nil
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}
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return nil, fmt.Errorf("Unknown encoding: %s", encoding)
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}
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func isEmbeddedFile(part *multipart.Part) bool {
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return part.Header.Get("Content-Transfer-Encoding") != ""
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}
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func decodeEmbeddedFile(part *multipart.Part) (ef EmbeddedFile, err error) {
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cid := decodeMimeSentence(part.Header.Get("Content-Id"))
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decoded, err := decodePartData(part)
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if err != nil {
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return
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}
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ef.CID = strings.Trim(cid, "<>")
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ef.Data = decoded
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ef.ContentType = part.Header.Get("Content-Type")
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return
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}
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func isAttachment(part *multipart.Part) bool {
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return part.FileName() != ""
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}
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func decodeAttachment(part *multipart.Part) (at Attachment, err error) {
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filename := decodeMimeSentence(part.FileName())
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decoded, err := decodePartData(part)
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if err != nil {
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return
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}
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at.Filename = filename
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at.Data = decoded
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at.ContentType = strings.Split(part.Header.Get("Content-Type"), ";")[0]
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return
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}
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type headerParser struct {
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header *mail.Header
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err error
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}
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func (hp headerParser) parseAddress(s string) (ma *mail.Address) {
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if hp.err != nil {
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return nil
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}
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if strings.Trim(s, " \n") != "" {
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ma, hp.err = mail.ParseAddress(s)
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return ma
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}
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return nil
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}
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func (hp headerParser) parseAddressList(s string) (ma []*mail.Address) {
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if hp.err != nil {
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return
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}
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if strings.Trim(s, " \n") != "" {
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ma, hp.err = mail.ParseAddressList(s)
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return
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}
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return
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}
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func (hp headerParser) parseTime(s string) (t time.Time) {
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if hp.err != nil || s == "" {
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return
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}
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t, hp.err = time.Parse(time.RFC1123Z, s)
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if hp.err == nil {
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return t
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}
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t, hp.err = time.Parse("Mon, 2 Jan 2006 15:04:05 -0700", s)
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return
|
||
|
|
}
|
||
|
|
|
||
|
|
func (hp headerParser) parseMessageId(s string) string {
|
||
|
|
if hp.err != nil {
|
||
|
|
return ""
|
||
|
|
}
|
||
|
|
|
||
|
|
return strings.Trim(s, "<> ")
|
||
|
|
}
|
||
|
|
|
||
|
|
func (hp headerParser) parseMessageIdList(s string) (result []string) {
|
||
|
|
if hp.err != nil {
|
||
|
|
return
|
||
|
|
}
|
||
|
|
|
||
|
|
for _, p := range strings.Split(s, " ") {
|
||
|
|
if strings.Trim(p, " \n") != "" {
|
||
|
|
result = append(result, hp.parseMessageId(p))
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
return
|
||
|
|
}
|
||
|
|
|
||
|
|
// Attachment with filename, content type and data (as a io.Reader)
|
||
|
|
type Attachment struct {
|
||
|
|
Filename string
|
||
|
|
ContentType string
|
||
|
|
Data io.Reader
|
||
|
|
}
|
||
|
|
|
||
|
|
// EmbeddedFile with content id, content type and data (as a io.Reader)
|
||
|
|
type EmbeddedFile struct {
|
||
|
|
CID string
|
||
|
|
ContentType string
|
||
|
|
Data io.Reader
|
||
|
|
}
|
||
|
|
|
||
|
|
// Email with fields for all the headers defined in RFC5322 with it's attachments and
|
||
|
|
type Email struct {
|
||
|
|
Header mail.Header
|
||
|
|
|
||
|
|
Subject string
|
||
|
|
Sender *mail.Address
|
||
|
|
From []*mail.Address
|
||
|
|
ReplyTo []*mail.Address
|
||
|
|
To []*mail.Address
|
||
|
|
Cc []*mail.Address
|
||
|
|
Bcc []*mail.Address
|
||
|
|
Date time.Time
|
||
|
|
MessageID string
|
||
|
|
InReplyTo []string
|
||
|
|
References []string
|
||
|
|
|
||
|
|
ResentFrom []*mail.Address
|
||
|
|
ResentSender *mail.Address
|
||
|
|
ResentTo []*mail.Address
|
||
|
|
ResentDate time.Time
|
||
|
|
ResentCc []*mail.Address
|
||
|
|
ResentBcc []*mail.Address
|
||
|
|
ResentMessageID string
|
||
|
|
|
||
|
|
HTMLBody string
|
||
|
|
TextBody string
|
||
|
|
|
||
|
|
Attachments []Attachment
|
||
|
|
EmbeddedFiles []EmbeddedFile
|
||
|
|
}
|