merkle_sync: fix _get_level_hashes — range query instead of exact mismatch (prefix encoding bug)

tools/chatgui/transport/merkle_sync.c

@@ -165,15 +165,31 @@ static int _get_level_hashes(struct merkle_sync* ms, const char* ns,
     memset(hashes, 0, sizeof(uint8_t) * MT_BUCKETS * MT_HASH_SIZE);
     *bitmap = 0;
     if (level >= MT_MAX_LEVEL) return 0;
-    int next_shift = 63 - ((int)level + 1) * 5;
 
-    for (int i = 0; i < MT_BUCKETS; i++) {
-        uint64_t child_prefix = prefix | ((uint64_t)i << (next_shift > 0 ? next_shift : 0));
-        const uint8_t* h = merkle_sync_get_hash(ms->inst, ns, (uint8_t)(level + 1), child_prefix);
-        int empty = 1;
-        for (int j = 0; j < MT_HASH_SIZE; j++) { if (h[j] != 0) { empty = 0; break; } }
-        if (!empty) { *bitmap |= (1u << i); memcpy(hashes[i], h, MT_HASH_SIZE); }
+    sqlite3* db = _db(ms->inst); if (!db) return -1;
+    int parent_shift = 63 - (int)level * 5; if (parent_shift < 0) parent_shift = 0;
+    int next_shift = 63 - ((int)level + 1) * 5; if (next_shift < 0) next_shift = 0;
+    uint64_t range_end = prefix | ((1ULL << parent_shift) - 1);
+
+    sqlite3_stmt* stmt = NULL;
+    if (sqlite3_prepare_v2(db,
+            "SELECT prefix64, hash FROM merkle_tree_hash"
+            " WHERE namespace=? AND level=? AND prefix64>=? AND prefix64<=?"
+            " ORDER BY prefix64", -1, &stmt, NULL) != SQLITE_OK || !stmt)
+        return -1;
+    sqlite3_bind_text(stmt, 1, ns, -1, SQLITE_STATIC);
+    sqlite3_bind_int(stmt, 2, (int)(level + 1));
+    sqlite3_bind_int64(stmt, 3, (sqlite3_int64)prefix);
+    sqlite3_bind_int64(stmt, 4, (sqlite3_int64)range_end);
+    while (sqlite3_step(stmt) == SQLITE_ROW) {
+        sqlite3_int64 row_pfx = sqlite3_column_int64(stmt, 0);
+        const void* h = sqlite3_column_blob(stmt, 1);
+        if (!h || sqlite3_column_bytes(stmt, 1) < MT_HASH_SIZE) continue;
+        int bucket = (int)(((uint64_t)row_pfx >> next_shift) & 0x1F);
+        *bitmap |= (1u << bucket);
+        memcpy(hashes[bucket], h, MT_HASH_SIZE);
     }
+    sqlite3_finalize(stmt);
     return 0;
 }