From 7adaeacd0b2ca50f89e7a9fb3ad82821dd0dfc2b Mon Sep 17 00:00:00 2001
From: Alexander Leisentritt <alexander@leisentritt.eu>
Date: Sat, 2 Nov 2019 18:55:10 +0100
Subject: [PATCH] refactored xiaomi ble data parsing (#823)

---
 esphome/components/xiaomi_ble/xiaomi_ble.cpp | 48 +++++++++++++++-----
 1 file changed, 36 insertions(+), 12 deletions(-)

diff --git a/esphome/components/xiaomi_ble/xiaomi_ble.cpp b/esphome/components/xiaomi_ble/xiaomi_ble.cpp
index 1172f6ee0a..e6884e5ea6 100644
--- a/esphome/components/xiaomi_ble/xiaomi_ble.cpp
+++ b/esphome/components/xiaomi_ble/xiaomi_ble.cpp
@@ -91,17 +91,6 @@ optional<XiaomiParseResult> parse_xiaomi(const esp32_ble_tracker::ESPBTDevice &d
     return {};
   }
 
-  uint8_t raw_offset = is_lywsdcgq || is_cgg1 ? 11 : 12;
-
-  const uint8_t raw_type = raw[raw_offset];
-  const uint8_t data_length = raw[raw_offset + 2];
-  const uint8_t *data = &raw[raw_offset + 3];
-  const uint8_t expected_length = data_length + raw_offset + 3;
-  const uint8_t actual_length = device.get_service_data().size();
-  if (expected_length != actual_length) {
-    // ESP_LOGV(TAG, "Xiaomi %s data length mismatch (%u != %d)", type, expected_length, actual_length);
-    return {};
-  }
   XiaomiParseResult result;
   result.type = XiaomiParseResult::TYPE_HHCCJCY01;
   if (is_lywsdcgq) {
@@ -111,7 +100,42 @@ optional<XiaomiParseResult> parse_xiaomi(const esp32_ble_tracker::ESPBTDevice &d
   } else if (is_cgg1) {
     result.type = XiaomiParseResult::TYPE_CGG1;
   }
-  bool success = parse_xiaomi_data_byte(raw_type, data, data_length, result);
+
+  uint8_t raw_offset = is_lywsdcgq || is_cgg1 ? 11 : 12;
+
+  // Data point specs
+  // Byte 0: type
+  // Byte 1: fixed 0x10
+  // Byte 2: length
+  // Byte 3..3+len-1: data point value
+
+  const uint8_t *raw_data = &raw[raw_offset];
+  uint8_t data_offset = 0;
+  uint8_t data_length = device.get_service_data().size() - raw_offset;
+  bool success = false;
+
+  while (true) {
+    if (data_length < 4)
+      // at least 4 bytes required
+      // type, fixed 0x10, length, 1 byte value
+      break;
+
+    const uint8_t datapoint_type = raw_data[data_offset + 0];
+    const uint8_t datapoint_length = raw_data[data_offset + 2];
+
+    if (data_length < 3 + datapoint_length)
+      // 3 fixed bytes plus value length
+      break;
+
+    const uint8_t *datapoint_data = &raw_data[data_offset + 3];
+
+    if (parse_xiaomi_data_byte(datapoint_type, datapoint_data, datapoint_length, result))
+      success = true;
+
+    data_length -= data_offset + 3 + datapoint_length;
+    data_offset += 3 + datapoint_length;
+  }
+
   if (!success)
     return {};
   return result;