att_db: add att db version as first byte, report error if version differs (also works for older db without version byte)

src/ble/att_db.c

@@ -200,6 +200,12 @@ static int att_copy_value(att_iterator_t *it, uint16_t offset, uint8_t * buffer,
 }
 
 void att_set_db(uint8_t const * db){
+    // validate db version
+    if (db == NULL) return;
+    if (*db++ != ATT_DB_VERSION){
+        log_error("ATT DB version differs, please regenerate .h from .gatt file or update att_db_util.c");
+        return;
+    }
     att_db = db;
 }
 

src/ble/att_db_util.c

@@ -52,7 +52,7 @@
 #ifdef MAX_ATT_DB_SIZE
 static uint8_t att_db_storage[MAX_ATT_DB_SIZE];
 #else
-#error Neither HAVE_MALLOC] nor MAX_ATT_DB_SIZE is defined. 
+#error Neither HAVE_MALLOC nor MAX_ATT_DB_SIZE is defined. 
 #endif
 #endif
 
@@ -75,7 +75,9 @@ void att_db_util_init(void){
 	att_db = att_db_storage;
 	att_db_max_size = sizeof(att_db_storage);
 #endif
-	att_db_size = 0;
+	// store att version
+	att_db[0] = ATT_DB_VERSION;
+	att_db_size = 1;
 	att_db_next_handle = 1;
 	att_db_util_set_end_tag();
 }

src/btstack_defines.h

@@ -301,6 +301,7 @@ typedef uint8_t sm_key_t[16];
 
 // ..
 // Internal properties reuse some GATT Characteristic Properties fields
+#define ATT_DB_VERSION                                     0x01
 
 // EVENTS
 

tool/compile_gatt.py

@@ -17,9 +17,10 @@ import sys
 
 header = '''
 // {0} generated from {1} for BTstack
+// att db format version 1
 
-// binary representation
-// attribute size in bytes (16), flags(16), handle (16), uuid (16/128), value(...)
+// binary attribute representation:
+// - size in bytes (16), flags(16), handle (16), uuid (16/128), value(...)
 
 #include <stdint.h>
 
@@ -825,7 +826,12 @@ def parse(fname_in, fin, fname_out, fout):
     
     fout.write(header.format(fname_out, fname_in))
     fout.write('{\n')
-    
+    write_indent(fout)
+    fout.write('// ATT DB Version\n')
+    write_indent(fout)
+    fout.write('1,\n')
+    fout.write("\n")
+ 
     parseLines(fname_in, fin, fout)
 
     serviceDefinitionComplete(fout)