Add basic solidity db contract

solidity/contracts/AltheaDB.sol

@@ -0,0 +1,52 @@
+//SPDX-License-Identifier: Apache-2.0
+pragma solidity 0.8.21; // Force solidity compliance
+
+contract AltheaDB {
+    // Identity struct
+    struct Identity {
+        string mesh_ip;
+        string wg_key;
+        address eth_addr;
+    }
+
+    // Mappings to regsitered clients
+    Identity[] private registered_users;
+    mapping(string => Identity) private wg_key_to_reg_users_map;
+    mapping(string => Identity) private mesh_ip_to_reg_users_map;
+    mapping(address => Identity) private eth_addr_to_reg_users_map;
+
+    // Add a new registered user
+    function add_registered_user(Identity memory entry) public {
+        registered_users.push(entry);
+        wg_key_to_reg_users_map[entry.wg_key] = entry;
+        mesh_ip_to_reg_users_map[entry.mesh_ip] = entry;
+        eth_addr_to_reg_users_map[entry.eth_addr] = entry;
+    }
+
+    // Get all registered users
+    function get_all_registered_users()
+        public
+        view
+        returns (Identity[] memory)
+    {
+        return registered_users;
+    }
+
+    function get_registered_client_with_wg_key(
+        string memory wg_key
+    ) public view returns (Identity memory) {
+        return wg_key_to_reg_users_map[wg_key];
+    }
+
+    function get_registered_client_with_mesh_ip(
+        string memory mesh_ip
+    ) public view returns (Identity memory) {
+        return mesh_ip_to_reg_users_map[mesh_ip];
+    }
+
+    function get_registered_client_with_eth_addr(
+        address eth_addr
+    ) public view returns (Identity memory) {
+        return eth_addr_to_reg_users_map[eth_addr];
+    }
+}