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Example of parsing a mime email message with Go (original: https://play.golang.org/p/v0QslNl5he)
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package main | |
import ( | |
"bytes" | |
"fmt" | |
"io" | |
"io/ioutil" | |
"log" | |
"mime" | |
"mime/multipart" | |
"net/mail" | |
"strings" | |
) | |
const myMessage = `Content-Type: multipart/alternative; | |
boundary="===============5769616449556512256==" | |
MIME-Version: 1.0 | |
To: test@test.com | |
From: test@gmail.com | |
Cc: | |
Subject: =?utf-8?b?0J/RgNC40LLQtdGC?= | |
Date: Mon, 30 Jun 2014 18:29:38 -0000 | |
--===============5769616449556512256== | |
Content-Type: text/plain; charset="utf-8" | |
MIME-Version: 1.0 | |
Content-Transfer-Encoding: base64 | |
X-Data: =?utf-8?b?AxfhfujropadladnggnfjgwsaiubvnmkadiuhterqHJSFfuAjkfhrqpeorLA?= | |
=?utf-8?b?kFnjNfhgt7Fjd9dfkliodQ==?= | |
0K3RgtC+INC80L7RkSDRgdC+0L7QsdGJ0LXQvdC40LUu | |
--===============5769616449556512256== | |
Content-Type: text/html; charset="utf-8" | |
MIME-Version: 1.0 | |
Content-Transfer-Encoding: base64 | |
0K3RgtC+INC80L7RkSDRgdC+0L7QsdGJ0LXQvdC40LUu | |
--===============5769616449556512256==--` | |
func main() { | |
msg, err := mail.ReadMessage(bytes.NewBufferString(myMessage)) | |
if err != nil { | |
log.Fatal("Cannot parse myMessage.") | |
} | |
to, _ := (&mail.AddressParser{}).ParseList(msg.Header.Get("To")) | |
fmt.Println("To", to) | |
mediaType, params, err := mime.ParseMediaType(msg.Header.Get("Content-Type")) | |
if err != nil { | |
log.Fatal(err) | |
} | |
if strings.HasPrefix(mediaType, "multipart/") { | |
mr := multipart.NewReader(msg.Body, params["boundary"]) | |
for { | |
p, err := mr.NextPart() | |
if err == io.EOF { | |
return | |
} | |
if err != nil { | |
log.Fatal(err) | |
} | |
// decode any Q-encoded values | |
for name, values := range p.Header { | |
for idx, val := range values { | |
fmt.Printf("%d: %s: %s\n", idx, name, decodeRFC2047(val)) | |
} | |
} | |
slurp, err := ioutil.ReadAll(p) | |
if err != nil { | |
log.Fatal(err) | |
} | |
fmt.Printf("Content-type: %s\n%s\n", p.Header.Get("Content-Type"), slurp) | |
} | |
} | |
} | |
// decodeRFC2047 ... | |
func decodeRFC2047(s string) string { | |
// GO 1.5 does not decode headers, but this may change in future releases... | |
decoded, err := (&mime.WordDecoder{}).DecodeHeader(s) | |
if err != nil || len(decoded) == 0 { | |
return s | |
} | |
return decoded | |
} |
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package main | |
import ( | |
"bufio" | |
"bytes" | |
"encoding/base64" | |
"errors" | |
"fmt" | |
"io" | |
"log" | |
"mime" | |
"mime/multipart" | |
"mime/quotedprintable" | |
"net/mail" | |
"strings" | |
) | |
// In this more complex version we are searching for the "text/plain" part. | |
const myMessage = `Content-Type: multipart/alternative; | |
boundary="===============5769616449556512256==" | |
MIME-Version: 1.0 | |
To: test@test.com | |
From: test@gmail.com | |
Cc: | |
Subject: =?utf-8?b?0J/RgNC40LLQtdGC?= | |
Date: Mon, 30 Jun 2014 18:29:38 -0000 | |
--===============5769616449556512256== | |
Content-Type: text/plain; charset="utf-8" | |
MIME-Version: 1.0 | |
Content-Transfer-Encoding: base64 | |
X-Data: =?utf-8?b?AxfhfujropadladnggnfjgwsaiubvnmkadiuhterqHJSFfuAjkfhrqpeorLA?= | |
=?utf-8?b?kFnjNfhgt7Fjd9dfkliodQ==?= | |
0K3RgtC+INC80L7RkSDRgdC+0L7QsdGJ0LXQvdC40LUu | |
--===============5769616449556512256== | |
Content-Type: text/html; charset="utf-8" | |
MIME-Version: 1.0 | |
Content-Transfer-Encoding: base64 | |
0K3RgtC+INC80L7RkSDRgdC+0L7QsdGJ0LXQvdC40LUu | |
--===============5769616449556512256==--` | |
func main() { | |
// msg, err := mail.ReadMessage(bytes.NewBufferString(myMessage)) | |
// if err != nil { | |
// log.Fatal("Cannot parse myMessage.") | |
// } | |
msg, err := ParseMessage(bytes.NewBufferString(myMessage)) | |
if err != nil { | |
log.Fatal(err) | |
} | |
// _ = msg | |
fmt.Println(msg) | |
// to, _ := (&mail.AddressParser{}).ParseList(msg.Header.Get("To")) | |
// fmt.Println("To", to) | |
// | |
// mediaType, params, err := mime.ParseMediaType(msg.Header.Get("Content-Type")) | |
// if err != nil { | |
// log.Fatal(err) | |
// } | |
// if strings.HasPrefix(mediaType, "multipart/") { | |
// mr := multipart.NewReader(msg.Body, params["boundary"]) | |
// for { | |
// p, err := mr.NextPart() | |
// if err == io.EOF { | |
// return | |
// } | |
// if err != nil { | |
// log.Fatal(err) | |
// } | |
// | |
// // decode any Q-encoded values | |
// for name, values := range p.Header { | |
// for idx, val := range values { | |
// fmt.Printf("%d: %s: %s\n", idx, name, decodeRFC2047(val)) | |
// } | |
// } | |
// | |
// slurp, err := ioutil.ReadAll(p) | |
// if err != nil { | |
// log.Fatal(err) | |
// } | |
// fmt.Printf("Content-type: %s\n%s\n", p.Header.Get("Content-Type"), slurp) | |
// } | |
// } | |
} | |
// ParseMessage parses and returns a Message from an io.Reader | |
// containing the raw text of an email message. | |
// (If the raw email is a string or []byte, use strings.NewReader() | |
// or bytes.NewReader() to create a reader.) | |
// Any "quoted-printable" or "base64" encoded bodies will be decoded. | |
func ParseMessage(r io.Reader) (io.Reader, error) { | |
msg, err := mail.ReadMessage(bufioReader(r)) | |
if err != nil { | |
return nil, err | |
} | |
// mediaType, params, err := mime.ParseMediaType(msg.Header.Get("Content-Type")) | |
// if err != nil { | |
// log.Fatal(err) | |
// } | |
// fmt.Println("ParseMessage mediatype:", mediaType, params) | |
// decode any Q-encoded values | |
for _, values := range msg.Header { | |
for idx, val := range values { | |
values[idx] = decodeRFC2047(val) | |
} | |
} | |
return parseMessageWithHeader(msg) | |
} | |
// parseMessageWithHeader parses and returns a Message from an already filled | |
// Header, and an io.Reader containing the raw text of the body/payload. | |
// (If the raw body is a string or []byte, use strings.NewReader() | |
// or bytes.NewReader() to create a reader.) | |
// Any "quoted-printable" or "base64" encoded bodies will be decoded. | |
func parseMessageWithHeader(msg *mail.Message) (io.Reader, error) { | |
// fmt.Println("parseMessageWithHeader", msg.Header) | |
bufferedReader := contentReader(msg.Header, msg.Body) | |
var err error | |
var mediaType string | |
var mediaTypeParams map[string]string | |
if contentType := msg.Header.Get("Content-Type"); len(contentType) > 0 { | |
mediaType, mediaTypeParams, err = mime.ParseMediaType(contentType) | |
fmt.Println("parseMessageWithHeader", mediaType) | |
if err != nil { | |
return nil, err | |
} | |
} // Lack of contentType is not a problem | |
// Can only have one of the following: Parts, SubMessage, or Body | |
if strings.HasPrefix(mediaType, "multipart") { | |
boundary := mediaTypeParams["boundary"] | |
parts, err := readParts(bufferedReader, boundary) | |
if err == nil { | |
if parts != nil { | |
return parts, nil | |
} | |
} | |
} else if strings.HasPrefix(mediaType, "message") { | |
return ParseMessage(bufferedReader) | |
} | |
if mediaType == "text/plain" { | |
return bufferedReader, nil | |
} | |
return nil, nil | |
} | |
// readParts parses out the parts of a multipart body, including the preamble and epilogue. | |
func readParts(bodyReader io.Reader, boundary string) (io.Reader, error) { | |
multipartReader := multipart.NewReader(bodyReader, boundary) | |
for part, partErr := multipartReader.NextPart(); partErr != io.EOF; part, partErr = multipartReader.NextPart() { | |
if partErr != nil && partErr != io.EOF { | |
return nil, partErr | |
} | |
fmt.Println("readParts", part.Header.Get("Content-Type")) | |
m, err := mail.ReadMessage(part) // fails to keep headers | |
if err != nil { | |
return nil, err | |
} | |
newEmailPart, msgErr := parseMessageWithHeader(m) | |
// part.Close() | |
if msgErr != nil { | |
return nil, msgErr | |
} | |
if newEmailPart != nil { | |
return newEmailPart, nil | |
} | |
} | |
return nil, errors.New("not found") | |
} | |
// contentReader ... | |
func contentReader(headers mail.Header, bodyReader io.Reader) *bufio.Reader { | |
if headers.Get("Content-Transfer-Encoding") == "quoted-printable" { | |
// headers.Del("Content-Transfer-Encoding") | |
return bufioReader(quotedprintable.NewReader(bodyReader)) | |
} | |
if headers.Get("Content-Transfer-Encoding") == "base64" { | |
// headers.Del("Content-Transfer-Encoding") | |
return bufioReader(base64.NewDecoder(base64.StdEncoding, bodyReader)) | |
} | |
return bufioReader(bodyReader) | |
} | |
// bufioReader ... | |
func bufioReader(r io.Reader) *bufio.Reader { | |
if bufferedReader, ok := r.(*bufio.Reader); ok { | |
return bufferedReader | |
} | |
return bufio.NewReader(r) | |
} | |
// decodeRFC2047 ... | |
func decodeRFC2047(s string) string { | |
// GO 1.5 does not decode headers, but this may change in future releases... | |
decoded, err := (&mime.WordDecoder{}).DecodeHeader(s) | |
if err != nil || len(decoded) == 0 { | |
return s | |
} | |
return decoded | |
} |
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This isn't a simple task as in addition to plain mime, emails also have base64, binary, and quoted-printable headers and bodies along with different character encodings.