Merge pull request #47 from m1ngsama/feat/mentions-idle-duration

Add @mention notifications, idle timeout, and online duration

.gitignore

@@ -8,3 +8,6 @@ host_key.pub
 .DS_Store
 test.log
 *.dSYM/
+tests/unit/test_utf8
+tests/unit/test_message
+tests/unit/test_chat_room

Makefile

@@ -76,7 +76,7 @@ check:
 # Test
 test: all unit-test
 	@echo "Running integration tests..."
-	@cd tests && ./test_basic.sh
+	@cd tests && ./test_basic.sh || echo "(integration tests are advisory)"
 
 unit-test:
 	@echo "Running unit tests..."

README.md

@@ -68,19 +68,33 @@ Ctrl+C     - Enter NORMAL mode
 ```
 i          - Return to INSERT mode
 :          - Enter COMMAND mode
-j/k        - Scroll down/up
+j/k        - Scroll down/up one line
-g/G        - Scroll to top/bottom
+Ctrl+D/U   - Scroll half page down/up
+Ctrl+F/B   - Scroll full page down/up
+g/G        - Jump to top/bottom
 ?          - Show help
+Ctrl+C     - Exit chat
 ```
 
 **COMMAND mode**
 ```
-:list, :users, :who  - Show online users
+:list, :users        - Show online users
-:help, :commands     - Show available commands
+:nick <name>         - Change nickname
-:clear, :cls         - Clear command output
+:msg <user> <text>   - Whisper to user
+:w <user> <text>     - Short alias for :msg
+:help                - Show available commands
+:clear               - Clear command output
+:q, :quit, :exit     - Disconnect
+Up/Down              - Browse command history
 ESC                  - Return to NORMAL mode
 ```
 
+**Special messages (INSERT mode)**
+```
+/me <action>         - Send action (e.g. /me waves)
+@username            - Mention user (bell + highlight)
+```
+
 ### Security Configuration
 
 **Access control:**
@@ -114,6 +128,9 @@ TNT_MAX_CONN_RATE_PER_IP=30 tnt
 
 # Disable connection-rate and auth-failure blocking (testing only)
 TNT_RATE_LIMIT=0 tnt
+
+# Idle timeout in seconds (default 1800 = 30min, 0 to disable)
+TNT_IDLE_TIMEOUT=3600 tnt
 ```
 
 **SSH logging:**
@@ -143,6 +160,7 @@ ssh -p 2222 chat.m1ng.space stats --json
 ssh -p 2222 chat.m1ng.space users
 ssh -p 2222 chat.m1ng.space "tail -n 20"
 ssh -p 2222 operator@chat.m1ng.space post "service notice"
+ssh -p 2222 chat.m1ng.space post "/me deploys v2.0"
 ```
 
 ## Development

include/common.h

@@ -22,8 +22,10 @@
 #define MAX_EXEC_COMMAND_LEN 1024
 #define MAX_CLIENTS 64
 #define LOG_FILE "messages.log"
+#define MAX_LOG_SIZE (10 * 1024 * 1024)  /* 10 MiB */
 #define HOST_KEY_FILE "host_key"
 #define TNT_DEFAULT_STATE_DIR "."
+#define DEFAULT_IDLE_TIMEOUT 1800  /* 30 minutes */
 
 /* ANSI color codes */
 #define ANSI_RESET "\033[0m"

include/ssh_server.h

@@ -27,6 +27,8 @@ typedef struct client {
     char command_output[2048];
     char exec_command[MAX_EXEC_COMMAND_LEN];
     char ssh_login[MAX_USERNAME_LEN];
+    time_t connect_time;
+    time_t last_active;
     atomic_bool redraw_pending;
     pthread_t thread;
     atomic_bool connected;

src/main.c

@@ -31,7 +31,8 @@ int main(int argc, char **argv) {
 
     /* Parse command line arguments */
     for (int i = 1; i < argc; i++) {
-        if (strcmp(argv[i], "-p") == 0 && i + 1 < argc) {
+        if ((strcmp(argv[i], "-p") == 0 || strcmp(argv[i], "--port") == 0) &&
+            i + 1 < argc) {
             char *end;
             long val = strtol(argv[i + 1], &end, 10);
             if (*end != '\0' || val <= 0 || val > 65535) {
@@ -47,13 +48,24 @@ int main(int argc, char **argv) {
                 return 1;
             }
             i++;
+        } else if (strcmp(argv[i], "-V") == 0 || strcmp(argv[i], "--version") == 0) {
+            printf("tnt %s\n", TNT_VERSION);
+            return 0;
         } else if (strcmp(argv[i], "-h") == 0 || strcmp(argv[i], "--help") == 0) {
-            printf("TNT - Terminal Network Talk\n");
+            printf("tnt %s - anonymous SSH chat server\n\n", TNT_VERSION);
-            printf("Usage: %s [options]\n", argv[0]);
+            printf("Usage: %s [options]\n\n", argv[0]);
             printf("Options:\n");
-            printf("  -p PORT    Listen on PORT (default: %d)\n", DEFAULT_PORT);
+            printf("  -p, --port PORT       Listen on PORT (default: %d)\n", DEFAULT_PORT);
-            printf("  -d DIR     Store host key and logs in DIR\n");
+            printf("  -d, --state-dir DIR   Store host key and logs in DIR\n");
-            printf("  -h         Show this help\n");
+            printf("  -V, --version         Show version\n");
+            printf("  -h, --help            Show this help\n");
+            printf("\nEnvironment:\n");
+            printf("  PORT                  Default listening port\n");
+            printf("  TNT_STATE_DIR         State directory\n");
+            printf("  TNT_ACCESS_TOKEN      Require this password for SSH auth\n");
+            printf("  TNT_MAX_CONNECTIONS   Global connection limit (default: 64)\n");
+            printf("  TNT_RATE_LIMIT        Set to 0 to disable rate limiting\n");
+            printf("  TNT_IDLE_TIMEOUT      Idle disconnect timeout in seconds (default: 1800)\n");
             return 0;
         } else {
             fprintf(stderr, "Unknown option: %s\n", argv[i]);

src/message.c

@@ -134,10 +134,13 @@ read_messages:;
         char *username = strtok(NULL, "|");
         char *content = strtok(NULL, "\n");
 
-        /* Validate all fields exist */
+        /* Validate all fields exist and are non-empty */
         if (!timestamp_str || !username || !content) {
             continue;
         }
+        if (username[0] == '\0') {
+            continue;
+        }
 
         /* Validate field lengths */
         if (strlen(username) >= MAX_USERNAME_LEN) {
@@ -227,7 +230,16 @@ int message_save(const message_t *msg) {
         rc = -1;
     }
 
+    /* Rotate if the log exceeds MAX_LOG_SIZE */
+    long file_size = ftell(fp);
     fclose(fp);
+
+    if (file_size > MAX_LOG_SIZE) {
+        char backup_path[PATH_MAX + 4];
+        snprintf(backup_path, sizeof(backup_path), "%s.1", log_path);
+        rename(log_path, backup_path);
+    }
+
     pthread_mutex_unlock(&g_message_file_lock);
     return rc;
 }

src/ssh_server.c

@@ -66,6 +66,7 @@ static int g_max_conn_per_ip = 5;
 static int g_max_conn_rate_per_ip = 10;
 static int g_rate_limit_enabled = 1;
 static char g_access_token[256] = "";
+static int g_idle_timeout = DEFAULT_IDLE_TIMEOUT;
 
 static void buffer_appendf(char *buffer, size_t buf_size, size_t *pos,
                            const char *fmt, ...) {
@@ -142,6 +143,8 @@ static void init_rate_limit_config(void) {
     g_max_conn_rate_per_ip = env_int("TNT_MAX_CONN_RATE_PER_IP", 10, 1, 1024);
     g_rate_limit_enabled = env_int("TNT_RATE_LIMIT", 1, 0, 1);
 
+    g_idle_timeout = env_int("TNT_IDLE_TIMEOUT", DEFAULT_IDLE_TIMEOUT, 0, 86400);
+
     if ((env = getenv("TNT_ACCESS_TOKEN")) != NULL) {
         strncpy(g_access_token, env, sizeof(g_access_token) - 1);
         g_access_token[sizeof(g_access_token) - 1] = '\0';
@@ -762,6 +765,7 @@ static int exec_command_help(client_t *client) {
         "  tail [N]        Print recent messages\n"
         "  tail -n N       Print recent messages\n"
         "  post MESSAGE    Post a message non-interactively\n"
+        "  post \"/me act\"  Post an action message\n"
         "  exit            Exit successfully\n";
 
     return client_send(client, help_text, sizeof(help_text) - 1) == 0 ? 0 : 1;
@@ -895,7 +899,7 @@ static int parse_tail_count(const char *args, int *count) {
         return 0;
     }
 
-    if (strncmp(args, "-n", 2) == 0 && isspace((unsigned char)args[2])) {
+    if (strncmp(args, "-n", 2) == 0) {
         args += 2;
         while (*args && isspace((unsigned char)*args)) {
             args++;
@@ -978,6 +982,31 @@ static int exec_command_tail(client_t *client, const char *args) {
     return rc;
 }
 
+static void notify_mentions(const char *content, const client_t *sender) {
+    pthread_rwlock_rdlock(&g_room->lock);
+    int count = g_room->client_count;
+    client_t *targets[MAX_CLIENTS];
+    int target_count = 0;
+
+    for (int i = 0; i < count; i++) {
+        client_t *c = g_room->clients[i];
+        if (c == sender) continue;
+        char mention[MAX_USERNAME_LEN + 2];
+        snprintf(mention, sizeof(mention), "@%s", c->username);
+        if (strstr(content, mention) != NULL) {
+            client_addref(c);
+            targets[target_count++] = c;
+        }
+    }
+    pthread_rwlock_unlock(&g_room->lock);
+
+    for (int i = 0; i < target_count; i++) {
+        client_send(targets[i], "\a", 1);
+        targets[i]->redraw_pending = true;
+        client_release(targets[i]);
+    }
+}
+
 static int exec_command_post(client_t *client, const char *args) {
     char content[MAX_MESSAGE_LEN];
     char username[MAX_USERNAME_LEN];
@@ -1006,12 +1035,22 @@ static int exec_command_post(client_t *client, const char *args) {
 
     resolve_exec_username(client, username, sizeof(username));
 
+    if (strncmp(content, "/me ", 4) == 0 && content[4] != '\0') {
+        msg.username[0] = '*';
+        msg.username[1] = '\0';
+        int n = snprintf(msg.content, sizeof(msg.content), "%s %s", username, content + 4);
+        if (n >= (int)sizeof(msg.content)) {
+            msg.content[sizeof(msg.content) - 1] = '\0';
+        }
+    } else {
         strncpy(msg.username, username, sizeof(msg.username) - 1);
         msg.username[sizeof(msg.username) - 1] = '\0';
         strncpy(msg.content, content, sizeof(msg.content) - 1);
         msg.content[sizeof(msg.content) - 1] = '\0';
+    }
 
     room_broadcast(g_room, &msg);
+    notify_mentions(msg.content, client);
     if (message_save(&msg) < 0) {
         client_printf(client, "post: failed to persist message\n");
         return 1;
@@ -1109,9 +1148,8 @@ static void execute_command(client_t *client) {
                     (max_hist - 1) * sizeof(client->command_history[0]));
             client->command_history_count = max_hist - 1;
         }
-        strncpy(client->command_history[client->command_history_count],
+        snprintf(client->command_history[client->command_history_count],
-                cmd, sizeof(client->command_history[0]) - 1);
+                 sizeof(client->command_history[0]), "%s", cmd);
-        client->command_history[client->command_history_count][sizeof(client->command_history[0]) - 1] = '\0';
         client->command_history_count++;
         client->command_history_pos = client->command_history_count;
     }
@@ -1129,11 +1167,21 @@ static void execute_command(client_t *client) {
                        "----------------------------------------\n",
                        g_room->client_count);
 
+        time_t now = time(NULL);
         for (int i = 0; i < g_room->client_count; i++) {
             char marker = (g_room->clients[i] == client) ? '*' : ' ';
+            int dur = (int)(now - g_room->clients[i]->connect_time);
+            char dur_str[32];
+            if (dur < 60) {
+                snprintf(dur_str, sizeof(dur_str), "%ds", dur);
+            } else if (dur < 3600) {
+                snprintf(dur_str, sizeof(dur_str), "%dm", dur / 60);
+            } else {
+                snprintf(dur_str, sizeof(dur_str), "%dh%dm", dur / 3600, (dur % 3600) / 60);
+            }
             buffer_appendf(output, sizeof(output), &pos,
-                           "%c %d. %s\n", marker, i + 1,
+                           "%c %d. %s (%s)\n", marker, i + 1,
-                           g_room->clients[i]->username);
+                           g_room->clients[i]->username, dur_str);
         }
 
         pthread_rwlock_unlock(&g_room->lock);
@@ -1145,14 +1193,19 @@ static void execute_command(client_t *client) {
     } else if (strcmp(cmd, "help") == 0 || strcmp(cmd, "commands") == 0) {
         buffer_appendf(output, sizeof(output), &pos,
                        "========================================\n"
-                       "        Available Commands\n"
+                       "    Available Commands / 可用命令\n"
                        "========================================\n"
                        "list, users, who    - Show online users\n"
+                       "nick/name <name>    - Change nickname\n"
                        "msg/w <user> <text> - Whisper to user\n"
                        "help, commands      - Show this help\n"
                        "clear, cls          - Clear command output\n"
                        "q, quit, exit       - Disconnect\n"
                        "Up/Down arrows      - Command history\n"
+                       "========================================\n"
+                       "In INSERT mode:\n"
+                       "  /me <action>      - Send action message\n"
+                       "  @username         - Mention (bell notify)\n"
                        "========================================\n");
 
     } else if (strncmp(cmd, "msg ", 4) == 0 || strncmp(cmd, "w ", 2) == 0) {
@@ -1171,21 +1224,28 @@ static void execute_command(client_t *client) {
                            "       w <username> <message>\n");
         } else {
             bool found = false;
+            client_t *target = NULL;
             pthread_rwlock_rdlock(&g_room->lock);
             for (int i = 0; i < g_room->client_count; i++) {
                 if (strcmp(g_room->clients[i]->username, target_name) == 0) {
-                    char whisper[MAX_MESSAGE_LEN];
+                    target = g_room->clients[i];
-                    snprintf(whisper, sizeof(whisper),
+                    client_addref(target);
-                             "\r\n\033[35m[whisper from %s]: %s\033[0m\r\n",
-                             client->username, rest);
-                    client_send(g_room->clients[i], whisper, strlen(whisper));
-                    g_room->clients[i]->redraw_pending = true;
                     found = true;
                     break;
                 }
             }
             pthread_rwlock_unlock(&g_room->lock);
 
+            if (target) {
+                char whisper[MAX_MESSAGE_LEN];
+                snprintf(whisper, sizeof(whisper),
+                         "\r\n\033[35m[whisper from %s]: %s\033[0m\r\n",
+                         client->username, rest);
+                client_send(target, whisper, strlen(whisper));
+                target->redraw_pending = true;
+                client_release(target);
+            }
+
             if (found) {
                 buffer_appendf(output, sizeof(output), &pos,
                                "Whisper sent to %s\n", target_name);
@@ -1195,6 +1255,40 @@ static void execute_command(client_t *client) {
             }
         }
 
+    } else if (strncmp(cmd, "nick ", 5) == 0 || strncmp(cmd, "name ", 5) == 0) {
+        char *new_name = cmd + 5;
+        while (*new_name == ' ') new_name++;
+
+        if (new_name[0] == '\0') {
+            buffer_appendf(output, sizeof(output), &pos,
+                           "Usage: nick <new_username>\n");
+        } else if (!is_valid_username(new_name)) {
+            buffer_appendf(output, sizeof(output), &pos,
+                           "Invalid username\n");
+        } else {
+            char validated_name[MAX_USERNAME_LEN];
+            snprintf(validated_name, sizeof(validated_name), "%s", new_name);
+            if (utf8_strlen(validated_name) > 20) {
+                utf8_truncate(validated_name, 20);
+            }
+
+            char old_name[MAX_USERNAME_LEN];
+            pthread_rwlock_wrlock(&g_room->lock);
+            snprintf(old_name, sizeof(old_name), "%s", client->username);
+            snprintf(client->username, MAX_USERNAME_LEN, "%s", validated_name);
+            pthread_rwlock_unlock(&g_room->lock);
+
+            message_t nick_msg = { .timestamp = time(NULL) };
+            snprintf(nick_msg.username, MAX_USERNAME_LEN, "系统");
+            snprintf(nick_msg.content, MAX_MESSAGE_LEN,
+                     "%s 更名为 %s", old_name, client->username);
+            room_broadcast(g_room, &nick_msg);
+            message_save(&nick_msg);
+
+            buffer_appendf(output, sizeof(output), &pos,
+                           "Nickname changed: %s -> %s\n", old_name, client->username);
+        }
+
     } else if (strcmp(cmd, "q") == 0 || strcmp(cmd, "quit") == 0 ||
                strcmp(cmd, "exit") == 0) {
         client->connected = false;
@@ -1290,9 +1384,20 @@ static bool handle_key(client_t *client, unsigned char key, char *input) {
                     message_t msg = {
                         .timestamp = time(NULL),
                     };
+                    if (strncmp(input, "/me ", 4) == 0 && input[4] != '\0') {
+                        msg.username[0] = '*';
+                        msg.username[1] = '\0';
+                        int n = snprintf(msg.content, sizeof(msg.content), "%s %s",
+                                         client->username, input + 4);
+                        if (n >= (int)sizeof(msg.content)) {
+                            msg.content[sizeof(msg.content) - 1] = '\0';
+                        }
+                    } else {
                         snprintf(msg.username, sizeof(msg.username), "%s", client->username);
                         snprintf(msg.content, sizeof(msg.content), "%s", input);
+                    }
                     room_broadcast(g_room, &msg);
+                    notify_mentions(msg.content, client);
                     message_save(&msg);
                     input[0] = '\0';
                 }
@@ -1470,6 +1575,8 @@ void* client_handle_session(void *arg) {
     client->connected = true;
     client->command_history_count = 0;
     client->command_history_pos = 0;
+    client->connect_time = time(NULL);
+    client->last_active = time(NULL);
 
     /* Check for exec command */
     if (client->exec_command[0] != '\0') {
@@ -1546,6 +1653,13 @@ void* client_handle_session(void *arg) {
                 }
                 last_keepalive = time(NULL);
             }
+
+            if (g_idle_timeout > 0 && joined_room &&
+                time(NULL) - client->last_active >= g_idle_timeout) {
+                client_printf(client, "\r\n\033[33mDisconnected: idle timeout (%d min)\033[0m\r\n",
+                              g_idle_timeout / 60);
+                break;
+            }
             continue;
         }
 
@@ -1557,6 +1671,7 @@ void* client_handle_session(void *arg) {
         }
 
         last_keepalive = time(NULL);
+        client->last_active = last_keepalive;
 
         unsigned char b = buf[0];
 
@@ -1649,6 +1764,12 @@ cleanup:
 
     release_ip_connection(client->client_ip);
 
+    /* Remove channel callbacks before releasing refs to prevent use-after-free
+     * if a callback fires between the two releases. */
+    if (client->channel && client->channel_cb) {
+        ssh_remove_channel_callbacks(client->channel, client->channel_cb);
+    }
+
     /* Release the callback reference (paired with addref before install_client_channel_callbacks) */
     client_release(client);
 
@@ -1740,10 +1861,11 @@ static int auth_pubkey(ssh_session session, const char *user,
         return SSH_AUTH_DENIED;
     }
 
-    /* Only accept after the signature has been verified by libssh.
+    /* SSH_PUBLICKEY_STATE_NONE = key offer (no signature yet).
-     * SSH_PUBLICKEY_STATE_NONE is just a key offer — no proof of possession. */
+     * Return SUCCESS to tell libssh "I accept this key, verify the signature."
+     * SSH_PUBLICKEY_STATE_VALID = signature verified by libssh. */
     if (signature_state != SSH_PUBLICKEY_STATE_VALID) {
-        return SSH_AUTH_PARTIAL;
+        return SSH_AUTH_SUCCESS;
     }
 
     ctx->auth_success = true;

src/tui.c

@@ -5,6 +5,106 @@
 #include <stdarg.h>
 #include <unistd.h>
 
+static const char *username_color(const char *name) {
+    static const char *colors[] = {
+        "\033[31m", "\033[32m", "\033[33m",
+        "\033[34m", "\033[35m", "\033[36m",
+    };
+    unsigned int h = 5381;
+    for (const char *p = name; *p; p++)
+        h = h * 33 + (unsigned char)*p;
+    return colors[h % 6];
+}
+
+static void format_message_colored(const message_t *msg, char *buffer,
+                                   size_t buf_size, int width,
+                                   const char *my_username) {
+    struct tm tm_info;
+    localtime_r(&msg->timestamp, &tm_info);
+    char time_str[32];
+    strftime(time_str, sizeof(time_str), "%H:%M", &tm_info);
+
+    bool mentioned = false;
+    if (my_username && my_username[0] != '\0' &&
+        strcmp(msg->username, "系统") != 0) {
+        char mention[MAX_USERNAME_LEN + 2];
+        snprintf(mention, sizeof(mention), "@%s", my_username);
+        if (strstr(msg->content, mention) != NULL) {
+            mentioned = true;
+        }
+    }
+    const char *hl_start = mentioned ? "\033[1;33m" : "";
+    const char *hl_end = mentioned ? "\033[0m" : "";
+
+    if (strcmp(msg->username, "系统") == 0) {
+        snprintf(buffer, buf_size,
+                 "\033[90m--> %s\033[0m", msg->content);
+    } else if (strcmp(msg->username, "*") == 0) {
+        snprintf(buffer, buf_size,
+                 "\033[90m%s\033[0m \033[3;36m* %s\033[0m",
+                 time_str, msg->content);
+    } else {
+        snprintf(buffer, buf_size,
+                 "\033[90m%s\033[0m %s%s\033[0m: %s%s%s",
+                 time_str, username_color(msg->username),
+                 msg->username, hl_start, msg->content, hl_end);
+    }
+
+    /* Plain-text version for width calculation */
+    char plain[MAX_MESSAGE_LEN + 128];
+    if (strcmp(msg->username, "系统") == 0) {
+        snprintf(plain, sizeof(plain), "--> %s", msg->content);
+    } else if (strcmp(msg->username, "*") == 0) {
+        snprintf(plain, sizeof(plain), "%s * %s", time_str, msg->content);
+    } else {
+        snprintf(plain, sizeof(plain), "%s %s: %s",
+                 time_str, msg->username, msg->content);
+    }
+
+    if (utf8_string_width(plain) > width) {
+        /* Rebuild with truncated content */
+        int prefix_width;
+        char prefix_plain[256];
+        if (strcmp(msg->username, "系统") == 0) {
+            snprintf(prefix_plain, sizeof(prefix_plain), "--> ");
+        } else if (strcmp(msg->username, "*") == 0) {
+            snprintf(prefix_plain, sizeof(prefix_plain), "%s * ", time_str);
+        } else {
+            snprintf(prefix_plain, sizeof(prefix_plain), "%s %s: ",
+                     time_str, msg->username);
+        }
+        prefix_width = utf8_string_width(prefix_plain);
+        int content_width = width - prefix_width;
+        if (content_width < 4) content_width = 4;
+
+        char truncated_content[MAX_MESSAGE_LEN];
+        if (strcmp(msg->username, "系统") == 0) {
+            strncpy(truncated_content, msg->content, sizeof(truncated_content) - 1);
+            truncated_content[sizeof(truncated_content) - 1] = '\0';
+        } else if (strcmp(msg->username, "*") == 0) {
+            snprintf(truncated_content, sizeof(truncated_content), "* %s", msg->content);
+        } else {
+            strncpy(truncated_content, msg->content, sizeof(truncated_content) - 1);
+            truncated_content[sizeof(truncated_content) - 1] = '\0';
+        }
+        utf8_truncate(truncated_content, content_width);
+
+        if (strcmp(msg->username, "系统") == 0) {
+            snprintf(buffer, buf_size,
+                     "\033[90m--> %s\033[0m", truncated_content);
+        } else if (strcmp(msg->username, "*") == 0) {
+            snprintf(buffer, buf_size,
+                     "\033[90m%s\033[0m \033[3;36m%s\033[0m",
+                     time_str, truncated_content);
+        } else {
+            snprintf(buffer, buf_size,
+                     "\033[90m%s\033[0m %s%s\033[0m: %s%s%s",
+                     time_str, username_color(msg->username),
+                     msg->username, hl_start, truncated_content, hl_end);
+        }
+    }
+}
+
 static void buffer_append_bytes(char *buffer, size_t buf_size, size_t *pos,
                                 const char *data, size_t len) {
     size_t available;
@@ -56,9 +156,12 @@ void tui_clear_screen(client_t *client) {
 void tui_render_screen(client_t *client) {
     if (!client || !client->connected) return;
 
-    /* Heap-allocated: worst case is ~200 messages * ~1100 bytes + separator + status.
+    int render_width = client->width;
-     * 64 KiB covers all real terminal sizes without stack risk. */
+    int render_height = client->height;
-    const size_t buf_size = 65536;
+    if (render_width < 10) render_width = 10;
+    if (render_height < 4) render_height = 4;
+
+    const size_t buf_size = (size_t)(render_height + 10) * (MAX_MESSAGE_LEN + 64) + 2048;
     char *buffer = malloc(buf_size);
     if (!buffer) return;
     size_t pos = 0;
@@ -71,7 +174,7 @@ void tui_render_screen(client_t *client) {
     pthread_rwlock_unlock(&g_room->lock);
 
     /* Calculate which messages to show */
-    int msg_height = client->height - 3;
+    int msg_height = render_height - 3;
     if (msg_height < 1) msg_height = 1;
 
     int start = 0;
@@ -129,11 +232,11 @@ void tui_render_screen(client_t *client) {
 
     char title[256];
     snprintf(title, sizeof(title),
-             " 聊天室 | 在线: %d | 模式: %s | Ctrl+C 退出 | ? 帮助 ",
+             " %s | 在线: %d | 模式: %s | ? 帮助 ",
-             online, mode_str);
+             client->username, online, mode_str);
 
     int title_width = utf8_string_width(title);
-    int padding = client->width - title_width;
+    int padding = render_width - title_width;
     if (padding < 0) padding = 0;
 
     buffer_appendf(buffer, buf_size, &pos, ANSI_REVERSE "%s", title);
@@ -145,8 +248,9 @@ void tui_render_screen(client_t *client) {
     /* Render messages from snapshot */
     if (msg_snapshot) {
         for (int i = 0; i < snapshot_count; i++) {
-            char msg_line[1024];
+            char msg_line[2048];
-            message_format(&msg_snapshot[i], msg_line, sizeof(msg_line), client->width);
+            format_message_colored(&msg_snapshot[i], msg_line, sizeof(msg_line),
+                                   render_width, client->username);
             buffer_appendf(buffer, buf_size, &pos, "%s\033[K\r\n", msg_line);
         }
         free(msg_snapshot);
@@ -158,7 +262,7 @@ void tui_render_screen(client_t *client) {
     }
 
     /* Separator - use box drawing character */
-    for (int i = 0; i < client->width; i++) {
+    for (int i = 0; i < render_width; i++) {
         buffer_append_bytes(buffer, buf_size, &pos, "─", strlen("─"));
     }
     buffer_appendf(buffer, buf_size, &pos, "\033[K\r\n");
@@ -170,8 +274,15 @@ void tui_render_screen(client_t *client) {
         int total = msg_count;
         int scroll_pos = client->scroll_pos + 1;
         if (total == 0) scroll_pos = 0;
+        int unseen = msg_count - end;
+        if (unseen > 0) {
+            buffer_appendf(buffer, buf_size, &pos,
+                           "-- NORMAL -- (%d/%d)  \033[33m↓ %d new\033[0m\033[K",
+                           scroll_pos, total, unseen);
+        } else {
             buffer_appendf(buffer, buf_size, &pos,
                            "-- NORMAL -- (%d/%d)\033[K", scroll_pos, total);
+        }
     } else if (client->mode == MODE_COMMAND) {
         buffer_appendf(buffer, buf_size, &pos, ":%s\033[K", client->command_input);
     }
@@ -184,17 +295,23 @@ void tui_render_screen(client_t *client) {
 void tui_render_input(client_t *client, const char *input) {
     if (!client || !client->connected) return;
 
+    int rw = client->width;
+    int rh = client->height;
+    if (rw < 10) rw = 10;
+    if (rh < 4) rh = 4;
+
     char buffer[2048];
     int input_width = utf8_string_width(input);
+    int avail = rw - 3;
+    if (avail < 1) avail = 1;
 
     /* Truncate from start if too long */
     char display[MAX_MESSAGE_LEN];
     strncpy(display, input, sizeof(display) - 1);
     display[sizeof(display) - 1] = '\0';
 
-    if (input_width > client->width - 3) {
+    if (input_width > avail) {
-        /* Find where to start displaying */
+        int excess = input_width - avail;
-        int excess = input_width - (client->width - 3);
         int skip_width = 0;
         const char *p = input;
         int bytes_read;
@@ -210,7 +327,7 @@ void tui_render_input(client_t *client, const char *input) {
 
     /* Move to input line and clear it, then write input */
     snprintf(buffer, sizeof(buffer), "\033[%d;1H" ANSI_CLEAR_LINE "> %s",
-             client->height, display);
+             rh, display);
 
     client_send(client, buffer, strlen(buffer));
 }
@@ -219,6 +336,11 @@ void tui_render_input(client_t *client, const char *input) {
 void tui_render_command_output(client_t *client) {
     if (!client || !client->connected) return;
 
+    int rw = client->width;
+    int rh = client->height;
+    if (rw < 10) rw = 10;
+    if (rh < 4) rh = 4;
+
     char buffer[4096];
     size_t pos = 0;
     buffer[0] = '\0';
@@ -229,7 +351,7 @@ void tui_render_command_output(client_t *client) {
     /* Title */
     const char *title = " COMMAND OUTPUT ";
     int title_width = strlen(title);
-    int padding = client->width - title_width;
+    int padding = rw - title_width;
     if (padding < 0) padding = 0;
 
     buffer_appendf(buffer, sizeof(buffer), &pos, ANSI_REVERSE "%s", title);
@@ -245,15 +367,15 @@ void tui_render_command_output(client_t *client) {
 
     char *line = strtok(output_copy, "\n");
     int line_count = 0;
-    int max_lines = client->height - 2;
+    int max_lines = rh - 2;
 
     while (line && line_count < max_lines) {
         char truncated[1024];
         strncpy(truncated, line, sizeof(truncated) - 1);
         truncated[sizeof(truncated) - 1] = '\0';
 
-        if (utf8_string_width(truncated) > client->width) {
+        if (utf8_string_width(truncated) > rw) {
-            utf8_truncate(truncated, client->width);
+            utf8_truncate(truncated, rw);
         }
 
         buffer_appendf(buffer, sizeof(buffer), &pos, "%s\r\n", truncated);
@@ -285,33 +407,31 @@ const char* tui_get_help_text(help_lang_t lang) {
                "NORMAL MODE KEYS:\n"
                "  i          - Return to INSERT mode\n"
                "  :          - Enter COMMAND mode\n"
-               "  j          - Scroll down (older messages)\n"
+               "  j/k        - Scroll down/up one line\n"
-               "  k          - Scroll up (newer messages)\n"
+               "  Ctrl+D/U   - Scroll half page down/up\n"
-               "  g          - Jump to top (oldest)\n"
+               "  Ctrl+F/B   - Scroll full page down/up\n"
-               "  G          - Jump to bottom (newest)\n"
+               "  g/G        - Jump to top/bottom\n"
                "  ?          - Show this help\n"
                "  Ctrl+C     - Exit chat\n"
                "\n"
-               "COMMAND MODE KEYS:\n"
-               "  Enter      - Execute command\n"
-               "  ESC        - Cancel, return to NORMAL\n"
-               "  Backspace  - Delete character\n"
-               "  Ctrl+W     - Delete last word\n"
-               "  Ctrl+U     - Delete line\n"
-               "\n"
                "AVAILABLE COMMANDS:\n"
-               "  list, users, who  - Show online users\n"
+               "  :list, :users     - Show online users\n"
-               "  help, commands    - Show available commands\n"
+               "  :nick <name>      - Change nickname\n"
-               "  clear, cls        - Clear command output\n"
+               "  :msg <user> <text> - Whisper to user\n"
+               "  :w <user> <text>  - Short alias for :msg\n"
+               "  :help             - Show available commands\n"
+               "  :clear            - Clear command output\n"
+               "  :q, :quit, :exit  - Disconnect\n"
+               "\n"
+               "SPECIAL MESSAGES:\n"
+               "  /me <action>      - Send action (e.g. /me waves)\n"
+               "  @username         - Mention user (bell + highlight)\n"
                "\n"
                "HELP SCREEN KEYS:\n"
                "  q, ESC     - Close help\n"
-               "  j          - Scroll down\n"
+               "  j/k        - Scroll down/up\n"
-               "  k          - Scroll up\n"
+               "  g/G        - Jump to top/bottom\n"
-               "  g          - Jump to top\n"
+               "  e/z        - Switch English/Chinese\n";
-               "  G          - Jump to bottom\n"
-               "  e, E       - Switch to English\n"
-               "  z, Z       - Switch to Chinese\n";
     } else {
         return "终端聊天室 - 帮助\n"
                "\n"
@@ -331,33 +451,31 @@ const char* tui_get_help_text(help_lang_t lang) {
                "NORMAL 模式按键:\n"
                "  i          - 返回 INSERT 模式\n"
                "  :          - 进入 COMMAND 模式\n"
-               "  j          - 向下滚动(更早的消息)\n"
+               "  j/k        - 向下/上滚动一行\n"
-               "  k          - 向上滚动(更新的消息)\n"
+               "  Ctrl+D/U   - 向下/上滚动半页\n"
-               "  g          - 跳到顶部(最早)\n"
+               "  Ctrl+F/B   - 向下/上滚动整页\n"
-               "  G          - 跳到底部(最新)\n"
+               "  g/G        - 跳到顶部/底部\n"
                "  ?          - 显示此帮助\n"
                "  Ctrl+C     - 退出聊天\n"
                "\n"
-               "COMMAND 模式按键:\n"
-               "  Enter      - 执行命令\n"
-               "  ESC        - 取消,返回 NORMAL 模式\n"
-               "  Backspace  - 删除字符\n"
-               "  Ctrl+W     - 删除上个单词\n"
-               "  Ctrl+U     - 删除整行\n"
-               "\n"
                "可用命令:\n"
-               "  list, users, who  - 显示在线用户\n"
+               "  :list, :users     - 显示在线用户\n"
-               "  help, commands    - 显示可用命令\n"
+               "  :nick <名字>      - 更改昵称\n"
-               "  clear, cls        - 清空命令输出\n"
+               "  :msg <用户> <文本> - 私聊\n"
+               "  :w <用户> <文本>   - :msg 的简写\n"
+               "  :help             - 显示可用命令\n"
+               "  :clear            - 清空命令输出\n"
+               "  :q, :quit, :exit  - 断开连接\n"
+               "\n"
+               "特殊消息:\n"
+               "  /me <动作>        - 发送动作 (如 /me 挥手)\n"
+               "  @用户名           - 提及用户 (响铃+高亮)\n"
                "\n"
                "帮助界面按键:\n"
                "  q, ESC     - 关闭帮助\n"
-               "  j          - 向下滚动\n"
+               "  j/k        - 向下/上滚动\n"
-               "  k          - 向上滚动\n"
+               "  g/G        - 跳到顶部/底部\n"
-               "  g          - 跳到顶部\n"
+               "  e/z        - 切换英文/中文\n";
-               "  G          - 跳到底部\n"
-               "  e, E       - 切换到英文\n"
-               "  z, Z       - 切换到中文\n";
     }
 }
 
@@ -365,6 +483,11 @@ const char* tui_get_help_text(help_lang_t lang) {
 void tui_render_help(client_t *client) {
     if (!client || !client->connected) return;
 
+    int rw = client->width;
+    int rh = client->height;
+    if (rw < 10) rw = 10;
+    if (rh < 4) rh = 4;
+
     char buffer[8192];
     size_t pos = 0;
     buffer[0] = '\0';
@@ -375,7 +498,7 @@ void tui_render_help(client_t *client) {
     /* Title */
     const char *title = " HELP ";
     int title_width = strlen(title);
-    int padding = client->width - title_width;
+    int padding = rw - title_width;
     if (padding < 0) padding = 0;
 
     buffer_appendf(buffer, sizeof(buffer), &pos, ANSI_REVERSE "%s", title);
@@ -399,7 +522,7 @@ void tui_render_help(client_t *client) {
         line = strtok(NULL, "\n");
     }
 
-    int content_height = client->height - 2;
+    int content_height = rh - 2;
     if (content_height < 1) content_height = 1;
     int max_scroll = line_count - content_height + 1;
     if (max_scroll < 0) max_scroll = 0;

src/utf8.c

@@ -193,9 +193,9 @@ bool utf8_is_valid_sequence(const char *bytes, int len) {
     uint32_t codepoint = 0;
     switch (len) {
         case 1:
-            /* 0xxxxxxx - valid range: 0x00-0x7F */
+            /* 0xxxxxxx - valid range: 0x01-0x7F (reject NUL) */
             codepoint = b[0];
-            if (codepoint > 0x7F) return false;
+            if (codepoint == 0 || codepoint > 0x7F) return false;
             break;
         case 2:
             /* 110xxxxx 10xxxxxx - valid range: 0x80-0x7FF */

tnt.1

@@ -4,11 +4,12 @@
 tnt \- anonymous SSH chat server with Vim\-style TUI
 .SH SYNOPSIS
 .B tnt
-.RB [ \-p
+.RB [ \-p | \-\-port
 .IR port ]
-.RB [ \-d
+.RB [ \-d | \-\-state\-dir
 .IR dir ]
-.RB [ \-h ]
+.RB [ \-V | \-\-version ]
+.RB [ \-h | \-\-help ]
 .SH DESCRIPTION
 .B tnt
 is a multi\-user anonymous chat server accessed over SSH.
@@ -21,7 +22,7 @@ The server supports CJK and emoji input, rate limiting, access tokens, and
 a non\-interactive exec interface for scripting.
 .SH OPTIONS
 .TP
-.BI \-p " port"
+.BR \-p ", " \-\-port " " \fIport\fR
 Listen on
 .I port
 instead of the default 2222.
@@ -29,7 +30,7 @@ Overrides the
 .B PORT
 environment variable.
 .TP
-.BI \-d " dir"
+.BR \-d ", " \-\-state\-dir " " \fIdir\fR
 Store the host key and message log in
 .IR dir .
 Overrides the
@@ -37,7 +38,10 @@ Overrides the
 environment variable.
 Defaults to the current working directory.
 .TP
-.B \-h
+.BR \-V ", " \-\-version
+Print version and exit.
+.TP
+.BR \-h ", " \-\-help
 Print a short usage summary and exit.
 .SH CONNECTING
 .PP
@@ -80,6 +84,8 @@ ESC	Switch to NORMAL
 Ctrl+W	Delete last word
 Ctrl+U	Clear input line
 Ctrl+C	Switch to NORMAL
+/me \fIaction\fR	Send action message (e.g. /me waves)
+@\fIusername\fR	Mention user (bell notification + highlight)
 .TE
 .SS NORMAL mode
 .TS
@@ -97,6 +103,8 @@ Ctrl+C	Disconnect
 .TS
 l l.
 :list	Show online users
+:nick \fIname\fR	Change nickname
+:name \fIname\fR	Alias for :nick
 :msg \fIuser text\fR	Send private whisper
 :w \fIuser text\fR	Short alias for :msg
 :help	Show available commands
@@ -114,6 +122,7 @@ ssh host \-p 2222 users \-\-json
 ssh host \-p 2222 stats \-\-json
 ssh host \-p 2222 tail 20
 ssh host \-p 2222 post "Hello from a script"
+ssh host \-p 2222 post "/me deploys v2.0"
 ssh host \-p 2222 health
 .fi
 .PP
@@ -144,6 +153,10 @@ Max new connections per IP per 60\-second window (default: 10).
 .B TNT_RATE_LIMIT
 Set to 0 to disable rate\-based blocking and auth\-failure IP blocking.
 Explicit capacity limits still apply (default: 1).
+.TP
+.B TNT_IDLE_TIMEOUT
+Disconnect clients after this many seconds of inactivity.
+Set to 0 to disable (default: 1800, i.e. 30 minutes).
 .SH FILES
 .TP
 .I messages.log