Merge pull request ReFirmLabs#776 from ReFirmLabs/dlink_tlv_no_checksum

Support dlink_tlv firmware that do not include the header checksum

src/signatures/dlink_tlv.rs

@@ -36,8 +36,8 @@ pub fn dlink_tlv_parser(
         if let Some(payload_data) = file_data.get(data_start..data_end) {
             let payload_md5 = format!("{:x}", md5::compute(payload_data));
 
-            // Make sure the MD5 hashes match
-            if payload_md5 == tlv_header.data_checksum {
+            // If the MD5 checksum exists, make sure it matches
+            if tlv_header.data_checksum.is_empty() || payload_md5 == tlv_header.data_checksum {
                 result.size = tlv_header.header_size + tlv_header.data_size;
                 result.description = format!(
                     "{}, model name: {}, board ID: {}, header size: {} bytes, data size: {} bytes",

src/structures/dlink_tlv.rs

@@ -43,11 +43,8 @@ pub fn parse_dlink_tlv_header(tlv_data: &[u8]) -> Result<DlinkTLVHeader, Structu
         header.data_checksum =
             get_cstring(&header_data[MD5_HASH_OFFSET..MD5_HASH_OFFSET + MAX_STRING_LENGTH]);
 
-        // Make sure we got the expected strings OK
-        if !header.model_name.is_empty()
-            && !header.board_id.is_empty()
-            && !header.data_checksum.is_empty()
-        {
+        // Make sure we got the expected strings OK (checksum is not always included)
+        if !header.model_name.is_empty() && !header.board_id.is_empty() {
             // Parse the type and length values that describe the data the follows the header
             if let Ok(data_tlv) =
                 common::parse(&header_data[DATA_TLV_OFFSET..], &tlv_structure, "little")