Index: apps/app_voicemail.c
===================================================================
--- apps/app_voicemail.c	(revision 376198)
+++ apps/app_voicemail.c	(working copy)
@@ -4484,34 +4484,49 @@
  */
 static const char *ast_str_encode_mime(struct ast_str **end, ssize_t maxlen, const char *start, size_t preamble, size_t postamble)
 {
-	struct ast_str *tmp = ast_str_alloca(80);
+	struct ast_str *buffer = ast_str_alloca(80);
 	int first_section = 1;
+	char qhead[80];
+	char qtail[] = "?=";
+	snprintf(qhead, sizeof(qhead), "=?%s?Q?", charset);
 
 	ast_str_reset(*end);
-	ast_str_set(&tmp, -1, "=?%s?Q?", charset);
+	ast_str_set(&buffer, -1, "%s", qhead);
+
+	/* Lots of nice info in:
+	 * http://tools.ietf.org/html/rfc5322#section-3.2.2 and
+	 * http://tools.ietf.org/html/rfc5322#section-2.2.3 */
 	for (; *start; start++) {
-		int need_encoding = 0;
-		if (*start < 33 || *start > 126 || strchr("()<>@,:;/\"[]?.=_", *start)) {
-			need_encoding = 1;
+		int need_encoding = (*start < 32 || *start > 126 || strchr("()<>@,:;/\"[]?.=_", *start));
+		int left_on_line = 76 - ast_str_strlen(buffer);
+		if (first_section) {
+			left_on_line -= preamble;
 		}
-		if ((first_section && need_encoding && preamble + ast_str_strlen(tmp) > 70) ||
-			(first_section && !need_encoding && preamble + ast_str_strlen(tmp) > 72) ||
-			(!first_section && need_encoding && ast_str_strlen(tmp) > 70) ||
-			(!first_section && !need_encoding && ast_str_strlen(tmp) > 72)) {
-			/* Start new line */
-			ast_str_append(end, maxlen, "%s%s?=", first_section ? "" : " ", ast_str_buffer(tmp));
-			ast_str_set(&tmp, -1, "=?%s?Q?", charset);
+		/* We break early on space, because:
+		 * (a) If we get multibyte input, we might break it in the middle
+		 *     of a character. If we're dealing with UTF-8, breaking on any
+		 *     byte < 127 is fine. If you're dealing with some other
+		 *     multibyte encoding, you're out of luck.
+		 * (b) According to RFC, the space used for folding should be
+		 *     included back into the unfolded element. Unfortunately the
+		 *     implementations vary. We add the trailing space in the
+		 *     q-encoded bit too. Two spaces is better than none.
+		 */
+		if (*start == ' ' || (need_encoding && left_on_line < 6) || (!need_encoding && left_on_line < 4)) {
+			/* Start new line (mark it as such by a space) */
+			ast_str_append(end, maxlen, "%s%s%s%s", first_section ? "" : " ", ast_str_buffer(buffer), *start == ' ' ? "_" : "", qtail);
+			ast_str_set(&buffer, -1, "%s", qhead);
 			first_section = 0;
 		}
-		if (need_encoding && *start == ' ') {
-			ast_str_append(&tmp, -1, "_");
-		} else if (need_encoding) {
-			ast_str_append(&tmp, -1, "=%hhX", *start);
-		} else {
-			ast_str_append(&tmp, -1, "%c", *start);
+		if (*start != ' ') {
+			if (need_encoding) {
+				ast_str_append(&buffer, -1, "=%hhX", *start);
+			} else {
+				ast_str_append(&buffer, -1, "%c", *start);
+			}
 		}
 	}
-	ast_str_append(end, maxlen, "%s%s?=%s", first_section ? "" : " ", ast_str_buffer(tmp), ast_str_strlen(tmp) + postamble > 74 ? " " : "");
+	ast_str_append(end, maxlen, "%s%s%s%s", first_section ? "" : " ", ast_str_buffer(buffer), qtail, ast_str_strlen(buffer) + postamble > 74 ? " " : "");
 	return ast_str_buffer(*end);
 }
 
@@ -4598,6 +4613,8 @@
 					fprintf(p, "%s %s" ENDL, first_line ? "From:" : "", ast_str_buffer(str2));
 					first_line = 0;
 					/* Substring is smaller, so this will never grow */
+					/* But we're assuming that the internal strcpy will work
+					 * with overlapping mem! FIXME */
 					ast_str_set(&str2, 0, "%s", ptr + 1);
 				}
 				fprintf(p, "%s %s <%s>" ENDL, first_line ? "From:" : "", ast_str_buffer(str2), who);
@@ -13093,6 +13110,64 @@
 	return res;
 }
 
+AST_TEST_DEFINE(test_q_encoding)
+{
+	int res = AST_TEST_FAIL;
+	char old_charset[32];
+	
+	switch (cmd) {
+	case TEST_INIT:
+		info->name = "q_encoding";
+		info->category = "/apps/app_voicemail/";
+		info->summary = "Test Q-encoding";
+		info->description =
+			"ASTERISK-20167";
+		return AST_TEST_NOT_RUN;
+	case TEST_EXECUTE:
+		break;
+	}
+
+	/* Switch to UTF-8 */
+	ast_copy_string(old_charset, charset, sizeof(old_charset));
+	ast_copy_string(charset, "UTF-8", sizeof(charset));
+	
+	/* Break out of the loop on failure */
+	do {
+		struct ast_str *output = ast_str_alloca(1024);
+		const char *input;
+		const char *expected;
+		const char *ret;
+
+		/* This breaks often, but it's better than breaking mid-utf-8 */
+		input = "Сообщение от \"anonymous\" <anonymous> в Monday, July 23, 2012 at 11:45:46 PM";
+		expected = "=?UTF-8?Q?=D0=A1=D0=BE=D0=BE=D0=B1=D1=89=D0=B5=D0=BD=D0=B8=D0=B5_?= "
+			   "=?UTF-8?Q?=D0=BE=D1=82_?= =?UTF-8?Q?=22anonymous=22_?= "
+			   "=?UTF-8?Q?=3Canonymous=3E_?= =?UTF-8?Q?=D0=B2_?= =?UTF-8?Q?Monday=2C_?= "
+			   "=?UTF-8?Q?July_?= =?UTF-8?Q?23=2C_?= =?UTF-8?Q?2012_?= =?UTF-8?Q?at_?= "
+			   "=?UTF-8?Q?11=3A45=3A46_?= =?UTF-8?Q?PM?=";
+		ret = ast_str_encode_mime(&output, 0, input, 0, 0);
+		if (strcmp(ret, expected)) {
+			ast_test_status_update(test, "Failed, expected:\n  \"\"\"%s\"\"\"\ngot:\n  \"\"\"%s\"\"\"\n", expected, ret);
+			break;
+		}
+
+		/* This breaks on 76 chars, but unfortunately mid-utf-8 */
+		input = "€€€€€€€€";
+		expected = "=?UTF-8?Q?=E2=82=AC=E2=82=AC=E2=82=AC=E2=82=AC=E2=82=AC=E2=82=AC=E2=82?= "
+			   "=?UTF-8?Q?=AC=E2=82=AC?="; /* <-- this break mid utf-8 is not cool, but it is the current implementation */
+		ret = ast_str_encode_mime(&output, 0, input, 2, 0); /* <-- preamble 2 to break mid-utf8 */
+		if (strcmp(ret, expected)) {
+			ast_test_status_update(test, "Failed, expected:\n  \"\"\"%s\"\"\"\ngot:\n  \"\"\"%s\"\"\"\n", expected, ret);
+			break;
+		}
+
+		res = AST_TEST_PASS;
+	} while(0);
+		
+	ast_copy_string(charset, old_charset, sizeof(charset));
+	return res;
+}
+	
 #endif /* defined(TEST_FRAMEWORK) */
 
 static int reload(void)
@@ -13118,6 +13193,7 @@
 	res |= AST_TEST_UNREGISTER(test_voicemail_vmuser);
 	res |= AST_TEST_UNREGISTER(test_voicemail_notify_endl);
 	res |= AST_TEST_UNREGISTER(test_voicemail_load_config);
+	res |= AST_TEST_UNREGISTER(test_q_encoding);
 #endif
 	ast_cli_unregister_multiple(cli_voicemail, ARRAY_LEN(cli_voicemail));
 	ast_uninstall_vm_functions();
@@ -13168,6 +13244,7 @@
 	res |= AST_TEST_REGISTER(test_voicemail_vmuser);
 	res |= AST_TEST_REGISTER(test_voicemail_notify_endl);
 	res |= AST_TEST_REGISTER(test_voicemail_load_config);
+	res |= AST_TEST_REGISTER(test_q_encoding);
 #endif
 
 	if (res)