lib-mail: istream-header-filter HEADER_FILTER_ADD_MISSING_EOH fixes

When using HEADER_FILTER_CRLF_PRESERVE, add CR to the EOH if the previous
header line ended with CRLF.

When header ends to a header without newline, add two newlines so we can get
the actual EOH added.

src/lib-mail/istream-header-filter.c

@@ -38,6 +38,8 @@ struct header_filter_istream {
 	unsigned int add_missing_eoh:1;
 	unsigned int end_body_with_lf:1;
 	unsigned int last_lf_added:1;
+	unsigned int last_orig_crlf:1;
+	unsigned int last_added_newline:1;
 	unsigned int eoh_not_matched:1;
 	unsigned int prev_matched:1;
 };
@@ -133,6 +135,8 @@ static void add_eol(struct header_filter_istream *mstream, bool orig_crlf)
 		buffer_append(mstream->hdr_buf, "\r\n", 2);
 	else
 		buffer_append_c(mstream->hdr_buf, '\n');
+	mstream->last_orig_crlf = orig_crlf;
+	mstream->last_added_newline = TRUE;
 }
 
 static ssize_t hdr_stream_update_pos(struct header_filter_istream *mstream)
@@ -284,6 +288,11 @@ static ssize_t read_header(struct header_filter_istream *mstream)
 		if (mstream->hdr_buf->used >= mstream->istream.max_buffer_size)
 			break;
 	}
+	if (mstream->hdr_buf->used > 0) {
+		const unsigned char *data = mstream->hdr_buf->data;
+		mstream->last_added_newline =
+			data[mstream->hdr_buf->used-1] == '\n';
+	}
 
 	if (hdr_ret < 0) {
 		if (mstream->istream.parent->stream_errno != 0) {
@@ -295,7 +304,9 @@ static ssize_t read_header(struct header_filter_istream *mstream)
 		}
 		if (!mstream->seen_eoh && mstream->add_missing_eoh) {
 			mstream->seen_eoh = TRUE;
-			add_eol(mstream, FALSE);
+			if (!mstream->last_added_newline)
+				add_eol(mstream, mstream->last_orig_crlf);
+			add_eol(mstream, mstream->last_orig_crlf);
 		}
 	}
 

src/lib-mail/test-istream-header-filter.c

@@ -349,6 +349,42 @@ static void test_istream_end_body_with_lf(void)
 	test_end();
 }
 
+static void test_istream_add_missing_eoh(void)
+{
+	struct {
+		const char *input;
+		const char *output;
+		unsigned int extra;
+	} tests[] = {
+		{ "From: foo", "From: foo\n\n", 1 },
+		{ "From: foo\n", "From: foo\n\n", 1 },
+		{ "From: foo\n\n", "From: foo\n\n", 1 },
+		{ "From: foo\n\nbar", "From: foo\n\nbar", 0 },
+		{ "From: foo\r\n", "From: foo\r\n\r\n", 1 },
+		{ "From: foo\r\n\r\n", "From: foo\r\n\r\n", 0 },
+		{ "From: foo\r\n\r\nbar", "From: foo\r\n\r\nbar", 0 }
+	};
+	struct istream *istream, *filter;
+	unsigned int i;
+
+	test_begin("i_stream_create_header_filter(add_missing_eoh)");
+	for (i = 0; i < N_ELEMENTS(tests); i++) {
+		istream = test_istream_create(tests[i].input);
+		filter = i_stream_create_header_filter(istream,
+					       HEADER_FILTER_EXCLUDE |
+					       HEADER_FILTER_CRLF_PRESERVE |
+					       HEADER_FILTER_ADD_MISSING_EOH,
+					       NULL, 0,
+					       *null_header_filter_callback, (void *)NULL);
+		test_istream_run(istream, filter,
+				 strlen(tests[i].input) + tests[i].extra,
+				 tests[i].output);
+		i_stream_unref(&filter);
+		i_stream_unref(&istream);
+	}
+	test_end();
+}
+
 static void ATTR_NULL(3)
 strip_eoh_callback(struct header_filter_istream *input ATTR_UNUSED,
 		   struct message_header_line *hdr,
@@ -383,6 +419,7 @@ int main(void)
 		test_istream_filter_large_buffer,
 		test_istream_callbacks,
 		test_istream_edit,
+		test_istream_add_missing_eoh,
 		test_istream_end_body_with_lf,
 		test_istream_strip_eoh,
 		NULL