From 5b52110399e991fa03480bfeb529e1fd0749fcc3 Mon Sep 17 00:00:00 2001
From: Leah Neukirchen <leah@vuxu.org>
Date: Sun, 9 May 2021 16:23:18 +0200
Subject: mmime: do not duplicate Content* headers

Do not add additional Content-Type and Content-Transfer-Encoding headers
when using mmime on input already containing them.

Do not reencode the message if Content-Transfer-Encoding is set.

Based on a patch by Felix Van der Jeugt and duncaen.
---
 mmime.c        | 28 +++++++++++++++++++++-------
 t/1000-mmime.t | 49 ++++++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 69 insertions(+), 8 deletions(-)

diff --git a/mmime.c b/mmime.c
index 4f06826..5c18171 100644
--- a/mmime.c
+++ b/mmime.c
@@ -387,6 +387,8 @@ gen_build()
 	int inheader = 1;
 	int intext = 0;
 	int ret = 0;
+	char *contenttype = 0;
+	char *contenttransferenc = 0;
 
 	while (1) {
 		ssize_t read = getdelim(&line, &linelen, '\n', stdin);
@@ -401,16 +403,24 @@ gen_build()
 				inheader = 0;
 				printf("MIME-Version: 1.0\n");
 				if (rflag) {
-					printf("Content-Type: text/plain; charset=UTF-8\n");
-					printf("Content-Transfer-Encoding: quoted-printable\n\n");
-
+					printf("Content-Type:%s", contenttype ? contenttype : " text/plain; charset=UTF-8\n");
+					printf("Content-Transfer-Encoding:%s", contenttransferenc ? contenttransferenc : " quoted-printable\n");
+					printf("\n");
 				} else {
 					printf("Content-Type: %s; boundary=\"%s\"\n", tflag, sep);
 					printf("\n");
 					printf("This is a multipart message in MIME format.\n");
 				}
 			} else {
-				print_header(line);
+				if (strncasecmp(line, "Content-Type:", 13) == 0) {
+					free(contenttype);
+					contenttype = strdup(line+13);
+				} else if (strncasecmp(line, "Content-Transfer-Encoding:", 26) == 0) {
+					free(contenttransferenc);
+					contenttransferenc = strdup(line+26);
+				} else {
+					print_header(line);
+				}
 			}
 			continue;
 		}
@@ -435,14 +445,18 @@ gen_build()
 
 		if (!rflag && !intext) {
 			printf("\n--%s\n", sep);
-			printf("Content-Type: text/plain; charset=UTF-8\n");
+			printf("Content-Type:%s", contenttype ? contenttype : " text/plain; charset=UTF-8\n");
 			printf("Content-Disposition: inline\n");
-			printf("Content-Transfer-Encoding: quoted-printable\n\n");
+			printf("Content-Transfer-Encoding:%s", contenttransferenc ? contenttransferenc : " quoted-printable\n");
+			printf("\n");
 
 			intext = 1;
 		}
 
-		gen_qp((uint8_t *)line, strlen(line), 78, 0);
+		if (contenttransferenc)
+			printf("%s", line);
+		else
+			gen_qp((uint8_t *)line, strlen(line), 78, 0);
 	}
 	if (!rflag && !inheader)
 		printf("\n--%s--\n", sep);
diff --git a/t/1000-mmime.t b/t/1000-mmime.t
index b0b0dc5..47ca63b 100755
--- a/t/1000-mmime.t
+++ b/t/1000-mmime.t
@@ -1,7 +1,7 @@
 #!/bin/sh -e
 cd ${0%/*}
 . ./lib.sh
-plan 8
+plan 12
 
 cat <<EOF >tmp
 References: <aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa@a> <bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb@b> <ccccccccccccccccccccccccccccccc@c>
@@ -42,3 +42,50 @@ Subject: inclusion test with other disposition
 EOF
 
 check 'include works, overriding filename' 'mmime <tmp2 | grep Disposition | grep inline'
+
+
+cat <<EOF >tmp2
+Subject: message with content-type
+Content-Type: text/plain; format=flowed
+
+This message has format-flowed.
+EOF
+
+check 'content-type is respected if found in input' 'mmime -r <tmp2 |grep format=flowed'
+
+cat <<EOF >tmp2
+Subject: message with content-transfer-encoding
+Content-Transfer-Encoding: quoted-printable
+
+This message has already encoded. f=C3=B6=C3=B6.
+EOF
+
+
+check 'content-transfer-encoding is respected if found in input' 'mmime -r <tmp2 |grep f=C3=B6=C3=B6'
+
+cat <<EOF >tmp2
+Subject: message with content-type
+Content-Type: text/plain; format=flowed
+
+This message has format-flowed.
+
+#message/rfc822 $PWD/tmp
+
+This part too.
+EOF
+
+
+check 'content-type is respected if found in input, for multipart/mixed' 'mmime <tmp2 |grep format=flowed'
+
+cat <<EOF >tmp2
+Subject: message with content-transfer-encoding
+Content-Transfer-Encoding: Quoted-Printable
+
+This message has already encoded. f=C3=B6=C3=B6.
+
+#message/rfc822 $PWD/tmp
+
+This part too.
+EOF
+
+check 'content-transfer-encoding is respected if found in input, for multipart/mixed' 'mmime <tmp2 |grep f=C3=B6=C3=B6'
-- 
cgit 1.4.1