From 955f7683af104b98ec67ef259f0cbe4c8f2a52ed Mon Sep 17 00:00:00 2001
From: Koni Marti <koni.marti@gmail.com>
Date: Thu, 2 Jun 2022 14:43:34 +0200
Subject: [PATCH] parse: fix content-type parsing error

If an error occurs when parsing the content-type, check if the
content-type is quoted; if so, remove quotes. If this is not the case,
then return a text/plain content-type as a sane fallback option, so that
the message can be at least viewed in plaintext.

Fixes: https://todo.sr.ht/~rjarry/aerc/44
Signed-off-by: Koni Marti <koni.marti@gmail.com>
Acked-by: Robin Jarry <robin@jarry.cc>
---
 worker/lib/parse.go                           | 27 ++++++++++-
 worker/lib/parse_test.go                      | 25 +++++++++++
 .../testdata/message/valid/quoted-mime-type   | 45 +++++++++++++++++++
 3 files changed, 96 insertions(+), 1 deletion(-)
 create mode 100644 worker/lib/testdata/message/valid/quoted-mime-type

diff --git a/worker/lib/parse.go b/worker/lib/parse.go
index 5d95046..bdd927f 100644
--- a/worker/lib/parse.go
+++ b/worker/lib/parse.go
@@ -64,12 +64,37 @@ func splitMIME(m string) (string, string) {
 	return parts[0], parts[1]
 }
 
+func fixContentType(h message.Header) (string, map[string]string) {
+	ct, rest := h.Get("Content-Type"), ""
+	if i := strings.Index(ct, ";"); i > 0 {
+		ct, rest = ct[:i], ct[i:]
+	}
+
+	// check if there are quotes around the content type
+	if strings.Contains(ct, "\"") {
+		header := strings.ReplaceAll(ct, "\"", "")
+		if rest != "" {
+			header += rest
+		}
+		h.Set("Content-Type", header)
+		if contenttype, params, err := h.ContentType(); err == nil {
+			return contenttype, params
+		}
+	}
+
+	// if all else fails, return text/plain
+	return "text/plain", nil
+}
+
 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)
+		// try to fix the error; if all measures fail, then return a
+		// text/plain content type to display at least plaintext
+		contentType, ctParams = fixContentType(e.Header)
 	}
+
 	mimeType, mimeSubType := splitMIME(contentType)
 	body.MIMEType = mimeType
 	body.MIMESubType = mimeSubType
diff --git a/worker/lib/parse_test.go b/worker/lib/parse_test.go
index 1219098..7e5bb36 100644
--- a/worker/lib/parse_test.go
+++ b/worker/lib/parse_test.go
@@ -10,6 +10,31 @@ import (
 	"git.sr.ht/~rjarry/aerc/models"
 )
 
+func TestMessageInfoParser(t *testing.T) {
+	rootDir := "testdata/message/valid"
+	msgFiles, err := ioutil.ReadDir(rootDir)
+	die(err)
+
+	for _, fi := range msgFiles {
+		if fi.IsDir() {
+			continue
+		}
+
+		p := fi.Name()
+		t.Run(p, func(t *testing.T) {
+			m := newMockRawMessageFromPath(filepath.Join(rootDir, p))
+			mi, err := MessageInfo(m)
+			if err != nil {
+				t.Fatal("Failed to create MessageInfo with:", err)
+			}
+
+			if perr := mi.Error; perr != nil {
+				t.Fatal("Expected no parsing error, but got:", mi.Error)
+			}
+		})
+	}
+}
+
 func TestMessageInfoHandledError(t *testing.T) {
 	rootDir := "testdata/message/invalid"
 	msgFiles, err := ioutil.ReadDir(rootDir)
diff --git a/worker/lib/testdata/message/valid/quoted-mime-type b/worker/lib/testdata/message/valid/quoted-mime-type
new file mode 100644
index 0000000..d9af28a
--- /dev/null
+++ b/worker/lib/testdata/message/valid/quoted-mime-type
@@ -0,0 +1,45 @@
+Subject: Your ECOLINES tickets
+X-PHP-Originating-Script: 33:functions.inc.php
+From: ECOLINES <ecolines@ecolines.lv>
+Content-Type: multipart/mixed;
+ boundary="PHP-mixed-ba319678ca12656cfb8cd46e736ce09d"
+Message-Id: <E1nvIQS-0004tm-Bc@legacy.ecolines.net>
+Date: Sun, 29 May 2022 15:53:44 +0300
+
+--PHP-mixed-ba319678ca12656cfb8cd46e736ce09d
+Content-Type: multipart/alternative; boundary="PHP-alt-ba319678ca12656cfb8cd46e736ce09d"
+
+--PHP-alt-ba319678ca12656cfb8cd46e736ce09d
+Content-Type: text/plain; charset="UTF-8"
+Content-Transfer-Encoding: 7bit
+
+Your tickets are attached to this message. Also You can print out Your tickets from our website www.ecolines.net<b
+r />
+…
+
+--PHP-alt-ba319678ca12656cfb8cd46e736ce09d
+Content-Type: text/html; charset="UTF-8"
+Content-Transfer-Encoding: 7bit
+
+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
+…
+
+--PHP-alt-ba319678ca12656cfb8cd46e736ce09d--
+
+--PHP-mixed-ba319678ca12656cfb8cd46e736ce09d
+Content-Type: "application/pdf"; name="17634428.pdf"
+Content-Disposition: attachment; filename="17634428.pdf"
+Content-Transfer-Encoding: base64
+
+JVBERi0xLjQKMSAwIG9iago8PAovVGl0bGUgKP7/AFkAbwB1AHIAIAB0AGkAYwBrAGUAdCkKL0Ny
+…
+
+--PHP-mixed-ba319678ca12656cfb8cd46e736ce09d
+Content-Type: "application/pdf"; name="invoice-6385490.pdf"
+Content-Disposition: attachment; filename="invoice-6385490.pdf"
+Content-Transfer-Encoding: base64
+
+JVBERi0xLjQKMSAwIG9iago8PAovVGl0bGUgKP7/AEkAbgB2AG8AaQBjAGUpCi9DcmVhdG9yICj+
+…
+
+--PHP-mixed-ba319678ca12656cfb8cd46e736ce09d--