From ffabbf91237cb3b11f0dcb03334fe8f1e688d3e3 Mon Sep 17 00:00:00 2001
From: markus schnalke <meillo@marmaro.de>
Date: Wed, 24 Sep 2014 16:38:06 +0200
Subject: [PATCH] mhbuild: Transfer-encode MIME parts of type application
 always with base64 Application files likely contain NUL
 bytes. scan_content(), however, uses stdio to check the
 files to attach. NUL bytes break these checks. Instead of
 improving the checks to allow e.g. application/x-tex files
 to be sent using 7bit or QP encoding, it was chosen to take
 the easy way and send application files base64-encoded.

This solves a bug when attaching tar files. (tar files begin with a
header mostly filled with NUL bytes). Thanks to <philipp@bureaucracy.de>
for discovering and reporting the bug.
---
 uip/mhbuild.c |   46 +++++++++++-----------------------------------
 1 file changed, 11 insertions(+), 35 deletions(-)

diff --git a/uip/mhbuild.c b/uip/mhbuild.c
index 1b2afa5..fde4a1d 100644
--- a/uip/mhbuild.c
+++ b/uip/mhbuild.c
@@ -1239,10 +1239,10 @@ static int
 scan_content(CT ct)
 {
 	int len;
-	int check8bit = 0, contains8bit = 0;  /* check if contains 8bit data */
-	int checklinelen = 0, linelen = 0;  /* check for long lines */
-	int checkboundary = 0, boundaryclash = 0; /* check if clashes with multipart boundary   */
-	int checklinespace = 0, linespace = 0;  /* check if any line ends with space */
+	int check8bit = 0, contains8bit = 0;
+	int checklinelen = 0, linelen = 0;
+	int checkboundary = 0, boundaryclash = 0;
+	int checklinespace = 0, linespace = 0;  /* trailing whitespace */
 	unsigned char *cp = NULL, buffer[BUFSIZ];
 	struct text *t = NULL;
 	FILE *in = NULL;
@@ -1297,13 +1297,6 @@ scan_content(CT ct)
 		}
 		break;
 
-	case CT_APPLICATION:
-		check8bit = 1;
-		checklinelen = 1;
-		checklinespace = 1;
-		checkboundary = 1;
-		break;
-
 	case CT_MESSAGE:
 		check8bit = 0;
 		checklinelen = 0;
@@ -1311,13 +1304,10 @@ scan_content(CT ct)
 		checkboundary = 1;
 		break;
 
+	case CT_APPLICATION:
 	case CT_AUDIO:
 	case CT_IMAGE:
 	case CT_VIDEO:
-		/*
-		** Don't check anything for these types,
-		** since we are forcing use of base64.
-		*/
 		check8bit = 0;
 		checklinelen = 0;
 		checklinespace = 0;
@@ -1334,9 +1324,6 @@ scan_content(CT ct)
 		len = strlen(prefix);
 
 		while (fgets(buffer, sizeof(buffer) - 1, in)) {
-			/*
-			** Check for 8bit data.
-			*/
 			if (check8bit) {
 				for (cp = buffer; *cp; cp++) {
 					if (!isascii(*cp)) {
@@ -1347,17 +1334,11 @@ scan_content(CT ct)
 				}
 			}
 
-			/*
-			** Check line length.
-			*/
 			if (checklinelen && (strlen(buffer) > CPERLIN + 1)) {
 				linelen = 1;
 				checklinelen = 0;  /* no need to keep checking */
 			}
 
-			/*
-			** Check if line ends with a space.
-			*/
 			if (checklinespace &&
 					(cp = buffer + strlen(buffer) - 2) >
 					buffer && isspace(*cp)) {
@@ -1426,24 +1407,19 @@ scan_content(CT ct)
 			ct->c_encoding = CE_7BIT;
 		break;
 
-	case CT_APPLICATION:
-		/* For application type, use base64, except when postscript */
-		if (contains8bit || linelen || linespace)
-			ct->c_encoding = (ct->c_subtype ==
-					APPLICATION_POSTSCRIPT) ?
-					CE_QUOTED : CE_BASE64;
-		else
-			ct->c_encoding = CE_7BIT;
-		break;
-
 	case CT_MESSAGE:
 		ct->c_encoding = CE_7BIT;
 		break;
 
+	case CT_APPLICATION:
 	case CT_AUDIO:
 	case CT_IMAGE:
 	case CT_VIDEO:
-		/* For audio, image, and video contents, just use base64 */
+		/*
+		** Forcing use of base64, because these types likely
+		** contain binary data and NUL bytes. Don't care about
+		** files that would be clean.
+		*/
 		ct->c_encoding = CE_BASE64;
 		break;
 	}
-- 
1.7.10.4