diff --git a/include/db/records.h b/include/db/records.h
index 49cf682..99060ed 100644
--- a/include/db/records.h
+++ b/include/db/records.h
@@ -25,6 +25,8 @@ extern "C"
     int all_records_of(int problems_id, char** result);
 
     int records_count();
+    
+    int have_ac(const char* user_id, int problem_id);
 
 #ifdef __cplusplus
 }
diff --git a/include/server/config.h b/include/server/config.h
index 94d2151..b89f7c1 100644
--- a/include/server/config.h
+++ b/include/server/config.h
@@ -1,8 +1,6 @@
 #ifndef SERVER_CONFIG_H
 #define SERVER_CONFIG_H
 
-#include <stdbool.h>
-
 typedef struct
 {
     int server_port;
@@ -12,7 +10,7 @@ typedef struct
 void config_ctor(config_t* this);
 void config_dtor(config_t* this);
 
-bool config_read(config_t* this, const char* filename);
+int config_read(config_t* this, const char* filename);
 
 int print_config();
 
diff --git a/include/server/response.h b/include/server/response.h
index 2428e89..b20ba9e 100644
--- a/include/server/response.h
+++ b/include/server/response.h
@@ -58,6 +58,7 @@ void res_all_records(mg_connection* conn, const char* records);
 void res_all_records_by(mg_connection* conn, const char* records);
 void res_all_records_of(mg_connection* conn, const char* records);
 void res_records_count(mg_connection* conn, int count);
+void res_have_ac(mg_connection* conn, int status);
 
 void res_add_set(mg_connection* conn, int id);
 void res_get_set(mg_connection* conn, const char* set);
diff --git a/include/server/study.h b/include/server/study.h
index d2547db..e7bc2b6 100644
--- a/include/server/study.h
+++ b/include/server/study.h
@@ -5,6 +5,7 @@
 
 int problems_handler(mg_connection* conn, void* cbdata);
 int records_handler(mg_connection* conn, void* cbdata);
+int sets_handler(mg_connection* conn, void* cbdata);
 
 extern char* secret;
 
diff --git a/src/db/records.cpp b/src/db/records.cpp
index 257766c..afb0201 100644
--- a/src/db/records.cpp
+++ b/src/db/records.cpp
@@ -2,18 +2,20 @@
 
 #include <chrono>
 #include <print>
-
+#include <unordered_map>
+#include <unordered_set>
 
 #include <leveldb/db.h>
 
 #include <nlohmann/json.hpp>
 
-
 using leveldb_ptr = leveldb::DB*;
 
 auto records_db     = leveldb_ptr{nullptr};
 auto records_count_ = 0;
 
+auto records = std::unordered_map<std::string, std::unordered_set<int>>{};
+
 extern "C"
 {
     int open_records_db()
@@ -29,8 +31,21 @@ extern "C"
             return 0;
         }
 
+        auto user_id_buf    = std::string{};
+        auto problem_id_buf = 0;
+        auto status_buf     = std::string{};
+
         auto it = records_db->NewIterator(leveldb::ReadOptions());
         for (it->SeekToFirst(); it->Valid(); it->Next()) {
+            auto json = nlohmann::json::parse(it->value().ToString());
+            // std::println(stderr, "{}", json.dump());
+            json["data"]["status"].get_to(status_buf);
+            if (status_buf == "ac") {
+                // std::println(stderr, "{}", json.dump());
+                json["user_id"].get_to(user_id_buf);
+                json["problem"].get_to(problem_id_buf);
+                records[user_id_buf].emplace(problem_id_buf);
+            }
             records_count_++;
         }
 
@@ -163,4 +178,9 @@ extern "C"
     {
         return records_count_;
     }
+
+    int have_ac(const char* user_id, int problem_id)
+    {
+        return records[user_id].contains(problem_id);
+    }
 }
\ No newline at end of file
diff --git a/src/main.c b/src/main.c
index e101db6..626bc2f 100644
--- a/src/main.c
+++ b/src/main.c
@@ -1,12 +1,14 @@
+#include "db/problems.h"
+#include "db/records.h"
+#include "db/sets.h"
 #include "server/auth.h"
 #include "server/config.h"
+#include "server/study.h"
 #include "server/types.h"
 
-#include "jwt/jwt.h"
+#include "hash/hash.h"
 
 #include "db/auth.h"
-#include "db/db.h"
-
 
 #include <civetweb.h>
 
@@ -15,127 +17,162 @@
 #include <stdlib.h>
 #include <string.h>
 
-leveldb_t* db = NULL;
-
 void signal_handler(int signal)
 {
-    fprintf(stderr, "Signal %d received, cleaning up...\n", signal);
-    close_db(db);
-    exit(1);
+    printf("Recieved signal %d.\n", signal);
+    exit(0);
+}
+
+void cleanup(void)
+{
+    if (admin_session) free(admin_session);
+    if (secret) free(secret);
+    close_sets_db();
+    close_records_db();
+    close_problems_db();
+    close_user_db();
+    printf("Cleanup.\n");
+}
+
+int reset_admin_password()
+{
+    char* random_password = kqm_random_password(16);
+    printf("Admin password is `%s`, "
+           "this password will not be showed again, "
+           "please save it well by yourself.\n",
+           random_password);
+
+    int flag = set_admin_password(random_password);
+
+    if (!flag) {
+        printf("cannot set admin password hash\n");
+    }
+    free(random_password);
+    return flag;
+}
+
+int init_admin_password()
+{
+    int result;
+    int flag = has_admin_password(&result);
+    if (flag) {
+        if (!result) {
+            flag = reset_admin_password();
+        }
+    } else {
+        printf("cannot check admin password hash\n");
+    }
+    return flag;
+}
+
+int init_db()
+{
+    if (!open_user_db()) {
+        fprintf(stderr, "cannot open user database\n");
+        return 1;
+    }
+    if (!open_problems_db()) {
+        fprintf(stderr, "cannot open problems database");
+        return 1;
+    }
+    if (!open_records_db()) {
+        fprintf(stderr, "cannot open records database\n");
+        return 1;
+    }
+    if (!open_sets_db()) {
+        fprintf(stderr, "cannot open problems set database\n");
+        return 1;
+    }
+
 }
 
 int main(int argc, char** argv)
 {
-    open_user_db();
+    /*
+    这一部分在 4.1.1。
+    */
+    if (atexit(cleanup)) {
+        printf("cannot register cleanup function\n");
+        return 1;
+    }
 
-    // while (1) {
-    //     printf("> ");
-    //     char op[16];
-    //     scanf("%15s", op);
-    //     if (strcmp(op, "exit") == 0) break;
-    //     if (strcmp(op, "login") == 0) {
-    //         char user_id[64];
-    //         char password[64];
-    //         scanf("%63s %63s", user_id, password);
-    //         int result;
-    //         int flag  = login(user_id, password, &result);
-    //         if (!flag) {
-    //             printf("Failed to login\n");
-    //         } else {
-    //             printf("Result: %s\n", result ? "login success" : "login failed");
-    //         }
-    //     }else if(strcmp(op, "logout") == 0){
-    //         char user_id[64];
-    //         scanf("%63s", user_id);
-    //         int flag = logout(user_id);
-    //         if (!flag) {
-    //             printf("Failed to logout\n");
-    //         } else {
-    //             printf("Logout success\n");
-    //         }
-    //     } else if (strcmp(op, "register") == 0) {
-    //         char user_id[64];
-    //         char password[64];
-    //         scanf("%63s %63s", user_id, password);
-    //         int result;
-    //         int flag = check_user_exists(user_id, &result);
-    //         if(!flag){
-    //             printf("Failed to check user existence\n");
-    //             continue;
-    //         }else if (result) {
-    //             printf("User already exists\n");
-    //             continue;
-    //         }
-    //         flag = set_user_password(user_id, password);
-    //         if (!flag) {
-    //             printf("Failed to register\n");
-    //         } else {
-    //             printf("Registration success\n");
-    //         }
-    //     } else if (strcmp(op, "check") == 0) {
-    //         char user_id[64];
-    //         scanf("%63s", user_id);
-    //         int result;
-    //         int flag = check_user_exists(user_id, &result);
-    //         if (!flag) {
-    //             printf("Failed to check user existence\n");
-    //         } else {
-    //             printf("Result: %s\n", result ? "user exists" : "user does not exist");
-    //         }
-    //     }
-    // }
+    int flag = 0;
 
-    // getchar();
+    flag |= SIG_ERR == signal(SIGINT, signal_handler);
+    flag |= SIG_ERR == signal(SIGTERM, signal_handler);
+    flag |= SIG_ERR == signal(SIGABRT, signal_handler);
+    flag |= SIG_ERR == signal(SIGSEGV, signal_handler);
 
-    // char* jwt = create_token("Hello", "world");
-    // printf("JWT: %s\n", jwt);
-    // int flag = verify_token(jwt, "world");
-    // printf("Flag: %d\n", flag);
-    // char* id = get_payload(jwt);
-    // printf("ID: %s\n", id);
-    // free(id);
-    // free(jwt);
+    if (flag) {
+        printf("cannot register signal handler\n");
+        return 1;
+    }
 
-    // if (!(db = open_db("db/main"))) return 1;
+    if (!init_db()) {
+        return 1;
+    }
 
-    // signal(SIGINT, signal_handler);
-    // signal(SIGTERM, signal_handler);
-    // signal(SIGSEGV, signal_handler);
+    if (!init_admin_password()) {
+        fprintf(stderr, "cannot init admin password hash\n");
+        return 1;
+    }
+
+    if (argc > 1) {
+        if (!strcmp(argv[1], "repasswd")) {
+            int flag = reset_admin_password();
+            if (!flag) {
+                fprintf(stderr, "cannot reset admin password\n");
+            }
+            return !flag;
+        }
+    }
 
     config_t config;
-    int stat = config_read(&config, "configs/config.json");
-    if (!stat) {
-        printf("config_read() returned %d\n", stat);
+    flag = config_read(&config, "configs/config.json");
+    if (!flag) {
+        fprintf(stderr, "cannot read config file\n");
         config_dtor(&config);
         return 1;
     }
     if (config.server_port > 65535 || config.server_port <= 0) {
-        printf("Invalid server_port: %d\n", config.server_port);
+        printf("invalid server_port: %d\n", config.server_port);
         config_dtor(&config);
         return 1;
     }
-    secret = config.secret;
+    secret        = config.secret;
+    config.secret = NULL;
+    config_dtor(&config);
 
     char server_port_str[6];
     snprintf(server_port_str, sizeof(server_port_str), "%d", config.server_port);
 
-    const char* options[] =
-        {"document_root", "./www", "listening_ports", server_port_str, "error_log_file", "logs/civetweb.log", NULL};
+    const char* options[] = {"document_root",
+                             "./www",
+                             "listening_ports",
+                             server_port_str,
+                             "error_log_file",
+                             "logs/civetweb.log",
+                             NULL};
     mg_callbacks callbacks;
     mg_context* ctx;
 
     memset(&callbacks, 0, sizeof(callbacks));
     ctx = mg_start(&callbacks, NULL, options);
 
-    mg_set_request_handler(ctx, "/api/auth/login", login_handler, NULL);
-    mg_set_request_handler(ctx, "/api/auth/register", register_handler, NULL);
-    mg_set_request_handler(ctx, "/api/auth/delete", delete_handler, NULL);
+    mg_set_request_handler(ctx, "/api/auth/login", user_login_handler, NULL);
+    mg_set_request_handler(ctx, "/api/auth/register", user_register_handler, NULL);
+    mg_set_request_handler(ctx, "/api/auth/delete", user_delete_handler, NULL);
+    mg_set_request_handler(ctx, "/api/auth/repasswd", user_repasswd_handler, NULL);
+    mg_set_request_handler(ctx, "/api/auth/logout", user_logout_handler, NULL);
+    mg_set_request_handler(ctx, "/api/auth/permission", user_permission_handler, NULL);
+    mg_set_request_handler(ctx, "/api/auth/admin", admin_handler, NULL);
+
+    mg_set_request_handler(ctx, "/api/study/problems", problems_handler, NULL);
+    mg_set_request_handler(ctx, "/api/study/records", records_handler, NULL);
+    mg_set_request_handler(ctx, "/api/study/sets", sets_handler, NULL);
+
 
     printf("Server started on port(s) %s\n", mg_get_option(ctx, "listening_ports"));
     getchar();
     mg_stop(ctx);
-
-    close_user_db();
-    // close_db(db);
-    return 0;
 }
diff --git a/src/server/auth/logout.c b/src/server/auth/logout.c
index bb5345e..8531c80 100644
--- a/src/server/auth/logout.c
+++ b/src/server/auth/logout.c
@@ -14,36 +14,6 @@
 #include <stdlib.h>
 #include <string.h>
 
-// typedef struct
-// {
-//     char* token;
-//     char* user_id;
-// } logout_form_t;
-
-// static void logout_form_dtor(logout_form_t* form)
-// {
-//     if (form->token) free(form->token);
-//     if (form->user_id) free(form->user_id);
-// }
-
-// static int field_found(const char* key, const char* filename, char* path, size_t pathlen, void* user_data)
-// {
-//     return MG_FORM_FIELD_HANDLE_GET;
-// }
-
-// static int field_get(const char* key, const char* value, size_t valuelen, void* user_data)
-// {
-//     logout_form_t* form = (logout_form_t*)user_data;
-//     if (strcmp(key, "token") == 0) {
-//         form->token = kqm_strndup(value, valuelen);
-//     } else if (strcmp(key, "user_id") == 0) {
-//         form->user_id = kqm_strndup(value, valuelen);
-//     }
-//     if (form->token && form->user_id) {
-//         return MG_FORM_FIELD_HANDLE_ABORT;
-//     }
-//     return MG_FORM_FIELD_HANDLE_GET;
-// }
 
 int user_logout_handler(mg_connection* conn, void* cbdata)
 {
@@ -61,62 +31,5 @@ int user_logout_handler(mg_connection* conn, void* cbdata)
 
     res_logout(conn);
 
-    // logout_form_t form = {NULL, NULL};
-
-    // mg_form_data_handler logout_callback = {
-    //     .field_found = field_found,
-    //     .field_get   = field_get,
-    //     .field_store = NULL,
-    //     .user_data   = &form,
-    // };
-
-    // mg_handle_form_request(conn, &logout_callback);
-
-    // if (!form.token) {
-    //     res_need_token(conn);
-    //     logout_form_dtor(&form);
-    //     return 1;
-    // }
-    // if (!verify_token(form.token, secret)) {
-    //     res_auth_fail(conn);
-    //     logout_form_dtor(&form);
-    //     return 1;
-    // }
-
-    // char* user_id = get_payload(form.token);
-
-    // if (form.user_id && strcmp(user_id, form.user_id)) {
-    //     int perm1;
-    //     int flag = get_user_permission(user_id, &perm1);
-    //     if (!flag) {
-    //         res_check_permission_fail(conn);
-    //     }
-
-    //     int perm2;
-    //     flag = get_user_permission(form.user_id, &perm2);
-    //     if (!flag) {
-    //         res_check_permission_fail(conn);
-    //     }
-
-    //     if (perm1 < perm2) {
-    //         int flag = logout_user(form.user_id);
-    //         if (!flag) {
-    //             res_logout_fail(conn);
-    //         } else {
-    //             res_logout(conn);
-    //         }
-    //     } else {
-    //         res_permission_denied(conn);
-    //     }
-    // } else {
-    //     int flag = logout_user(user_id);
-    //     if (!flag) {
-    //         res_logout_account_fail(conn);
-    //     } else {
-    //         res_logout_account(conn);
-    //     }
-    // }
-    // free(user_id);
-    // logout_form_dtor(&form);
     return 1;
 }
diff --git a/src/server/config.c b/src/server/config.c
index e806af4..75839f9 100644
--- a/src/server/config.c
+++ b/src/server/config.c
@@ -43,17 +43,17 @@ void config_dtor(config_t* this)
     if (this->secret) free(this->secret);
 }
 
-bool config_read(config_t* this, const char* filename)
+int config_read(config_t* this, const char* filename)
 {
     char* json_data = read_file(filename);
     if (json_data == NULL) {
-        return false;
+        return 0;
     }
 
     cJSON* root = cJSON_Parse(json_data);
     if (root == NULL) {
         free(json_data);
-        return false;
+        return 0;
     }
 
     cJSON* server_port = cJSON_GetObjectItem(root, "server_port");
@@ -73,5 +73,5 @@ bool config_read(config_t* this, const char* filename)
     cJSON_Delete(root);
     free(json_data);
 
-    return true;
+    return 1;
 }
diff --git a/src/server/response.c b/src/server/response.c
index b0120af..3289665 100644
--- a/src/server/response.c
+++ b/src/server/response.c
@@ -396,6 +396,16 @@ void res_records_count(mg_connection* conn, int count)
               count);
 }
 
+void res_have_ac(mg_connection* conn, int status)
+{
+    mg_printf(conn,
+              "HTTP/1.1 200 OK\r\n"
+              "Content-Type: application/json\r\n"
+              "Access-Control-Allow-Origin: *\r\n\r\n"
+              "{\"success\":\"success to check if have ac\", \"result\":%s}",
+              status ? "true" : "false");
+}
+
 void res_add_set(mg_connection* conn, int id)
 {
     mg_printf(conn,
diff --git a/src/server/study/records.c b/src/server/study/records.c
index 4a90e37..5b0431e 100644
--- a/src/server/study/records.c
+++ b/src/server/study/records.c
@@ -139,6 +139,21 @@ static void impl_count(mg_connection* conn)
     res_records_count(conn, count);
 }
 
+static void impl_have(mg_connection* conn, record_form_t* form)
+{
+    if (!form->user_id) {
+        res_need_xxx(conn, "user id");
+        return;
+    }
+    if (!form->has_problem_id) {
+        res_need_xxx(conn, "problem id");
+        return;
+    }
+
+    int status = have_ac(form->user_id, form->problem_id);
+    res_have_ac(conn, status);
+}
+
 int records_handler(mg_connection* conn, void* cbdata)
 {
     const mg_request_info* post_body = mg_get_request_info(conn);
@@ -176,6 +191,8 @@ int records_handler(mg_connection* conn, void* cbdata)
             impl_of(conn, &form);
         } else if (!strcmp(form.action, "count")) {
             impl_count(conn);
+        } else if (!strcmp(form.action, "have")) {
+            impl_have(conn, &form);
         } else {
             res_bad_action(conn);
         }
diff --git a/src/server/study/sets.c b/src/server/study/sets.c
index fbb2ae5..557a04a 100644
--- a/src/server/study/sets.c
+++ b/src/server/study/sets.c
@@ -229,11 +229,7 @@ int sets_handler(mg_connection* conn, void* cbdata)
                     impl_delete(conn, &form);
                 }
             } else if (!strcmp(form.action, "query")) {
-                if (result == 2) {
-                    res_permission_denied(conn);
-                } else {
-                    impl_query(conn, &form);
-                }
+                impl_query(conn, &form);
             } else if (!strcmp(form.action, "modify")) {
                 if (result == 2) {
                     res_permission_denied(conn);