Started work on MIME parser

I'm hoping to mostly rely on the official mime and mime/multipart packages, but Inbucket is still going to have to decided what to do with the various parts it reads.
2025-12-17 09:37:02 +00:00 · 2012-10-14 23:11:39 -07:00
parent da8e0bc508
commit 46b123606b
3 changed files with 163 additions and 0 deletions
--- a/app/inbucket/mime.go
+++ b/app/inbucket/mime.go
@@ -0,0 +1,81 @@
+package inbucket
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"mime"
+	"mime/multipart"
+	"net/mail"
+)
+
+const MIME_BUF_BYTES = 1024
+
+type MIMEMessage struct {
+	text string
+	html string
+}
+
+func ParseMIMEMessage(mailMsg *mail.Message) (*MIMEMessage, error) {
+	mimeMsg := new(MIMEMessage)
+
+	// Parse top-level multipart
+	ctype := mailMsg.Header.Get("Content-Type")
+	mediatype, params, err := mime.ParseMediaType(ctype)
+	if err != nil {
+		return nil, err
+	}
+	switch mediatype {
+	case "multipart/alternative":
+		// Good
+	default:
+		return nil, fmt.Errorf("Unknown mediatype: %v", mediatype)
+	}
+	boundary := params["boundary"]
+	if boundary == "" {
+		return nil, fmt.Errorf("Unable to locate boundary param in Content-Type header")
+	}
+
+	// Buffer used by Part.Read to hand us chunks of data
+	readBytes := make([]byte, MIME_BUF_BYTES)
+
+	// Loop over MIME parts
+	mr := multipart.NewReader(mailMsg.Body, boundary)
+	for {
+		part, err := mr.NextPart()
+		if err != nil {
+			if err == io.EOF {
+				// This is a clean end-of-message signal
+				break
+			}
+			return nil, err
+		}
+		mediatype, params, err = mime.ParseMediaType(part.Header.Get("Content-Type"))
+		if err != nil {
+			return nil, err
+		}
+		if mediatype == "text/plain" && mimeMsg.text == "" {
+			// First text section, we'll have that, but first we have to deal with
+			// the odd way Part lets us read data.
+			var buf bytes.Buffer
+			for {
+				n, err := part.Read(readBytes)
+				if err != nil {
+					if err == io.EOF {
+						// Clean end of part signal
+						break
+					}
+					return nil, err
+				}
+				// Extra data in readBytes is not cleared, so we must respect
+				// the value returned in 'n'
+				buf.Write(readBytes[:n])
+			}
+
+			mimeMsg.text = buf.String()
+			fmt.Printf("text: '%v'\n", mimeMsg.text)
+		}
+	}
+
+	return mimeMsg, nil
+}
--- a/app/inbucket/mime_test.go
+++ b/app/inbucket/mime_test.go
@@ -0,0 +1,28 @@
+package inbucket
+
+import (
+	"bufio"
+	"net/mail"
+	"os"
+	"testing"
+)
+
+func TestSomething(t *testing.T) {
+	// Open test email for parsing
+	raw, err := os.Open("../../test-data/html-mime-attach.raw")
+	if err != nil {
+		t.Fatalf("Failed to open test data: %v", err)
+	}
+
+	// Parse email into a mail.Message object like we do
+	reader := bufio.NewReader(raw)
+	msg, err := mail.ReadMessage(reader)
+	if err != nil {
+		t.Fatalf("Failed to read message: %v", err)
+	}
+
+	_, err = ParseMIMEMessage(msg)
+	if err != nil {
+		t.Fatalf("Failed to parse mime: %v", err)
+	}
+}
--- a/test-data/html-mime-attach.raw
+++ b/test-data/html-mime-attach.raw
@@ -0,0 +1,54 @@
+From: James Hillyerd <james@makita.skynet>
+Content-Type: multipart/alternative; boundary="Apple-Mail=_E091454E-BCFA-43B4-99C0-678AEC9868D6"
+Subject: MIME test 1
+Date: Sat, 13 Oct 2012 15:33:07 -0700
+Message-Id: <4E2E5A48-1A2C-4450-8663-D41B451DA93E@makita.skynet>
+To: greg@nobody.com
+Mime-Version: 1.0 (Apple Message framework v1283)
+X-Mailer: Apple Mail (2.1283)
+
+
+--Apple-Mail=_E091454E-BCFA-43B4-99C0-678AEC9868D6
+Content-Transfer-Encoding: 7bit
+Content-Type: text/plain;
+	charset=us-ascii
+
+Test of HTML section
+--Apple-Mail=_E091454E-BCFA-43B4-99C0-678AEC9868D6
+Content-Type: multipart/related;
+	type="text/html";
+	boundary="Apple-Mail=_D2ABE25A-F0FE-404E-94EE-D98BD23448D5"
+
+
+--Apple-Mail=_D2ABE25A-F0FE-404E-94EE-D98BD23448D5
+Content-Transfer-Encoding: 7bit
+Content-Type: text/html;
+	charset=us-ascii
+
+<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><font class="Apple-style-span" face="'Comic Sans MS'">Test of HTML section</font><img height="16" width="16" apple-width="yes" apple-height="yes" id="4579722f-d53d-45d0-88bc-f8209a2ca569" src="cid:8B8481A2-25CA-4886-9B5A-8EB9115DD064@skynet"></body></html>
+--Apple-Mail=_D2ABE25A-F0FE-404E-94EE-D98BD23448D5
+Content-Transfer-Encoding: base64
+Content-Disposition: inline;
+	filename=favicon.png
+Content-Type: image/png;
+	x-unix-mode=0644;
+	name="favicon.png"
+Content-Id: <8B8481A2-25CA-4886-9B5A-8EB9115DD064@skynet>
+
+iVBORw0KGgoAAAANSUhEUgAAABAAAAAQCAYAAAAf8/9hAAAAGXRFWHRTb2Z0d2FyZQBBZG9iZSBJ
+bWFnZVJlYWR5ccllPAAAAlFJREFUeNqUU8tOFEEUPVVdNV3dPe8xYRBnjGhmBgKjKzCIiQvBoIaN
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+yELl/aE1/83cp40Pt5mxqCKrE4Ck+mVWKKcI5tA8BLEhRBKJLjez6a7MLq7XZtp+yyOawwCBtkiB
+VZDKzRk4NN7NQBMYPHiZDFhXY+p9ff7F961vVcnl4R5I2ykJ5XFN7Ab7Gc61VoipNBKF+PDyztu5
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+pdw5WFoEwKWqWHacaWOjQXWGcifKo6vj5RGS6zykI587XeUIQDqJSmAp+lE4qt19W5P9o8+Lma5D
+cjsC8JiT607lMVkdqQ0Vyh3lHhmh52tfNy78ajXv0rgYzv8nfwswANuk+7sD/Q0aAAAAAElFTkSu
+QmCC
+
+--Apple-Mail=_D2ABE25A-F0FE-404E-94EE-D98BD23448D5--
+
+--Apple-Mail=_E091454E-BCFA-43B4-99C0-678AEC9868D6--