refactor: extract input module (PR2-M5)

Move the interactive session — username read, vim-style key dispatcher,
main poll/redraw/keepalive/idle-timeout loop, the @mention bell, and
the tear-down path — out of ssh_server.c into a dedicated module.

New API (include/input.h):
- input_init()                 -- read TNT_IDLE_TIMEOUT once at startup
- input_run_session(client_t*) -- run the interactive session for an
                                  already-bootstrapped client_t,
                                  including exec_dispatch() short-circuit
                                  when client->exec_command is set
- notify_mentions(content, sender) -- moved from ssh_server.h since
                                  the INSERT-mode send path lives here
                                  too

Renamed: client_handle_session(void *arg) -> input_run_session(client_t *).
The old void* signature was a fossil from when this was a pthread entry;
bootstrap.c calls it synchronously inside its own detached thread.
bootstrap_run() now ends with `input_run_session(client); return NULL;`.

g_idle_timeout is now private to input.c; ssh_server_init() calls
input_init() instead of reading the env directly.

ssh_server.c shrinks from 1026 to 402 lines (-624) -- now down to just
the accept loop, ssh_server_init / ssh_server_start, host-key setup,
client_t I/O API (send/printf/addref/release), and the post-bootstrap
client_channel_* callbacks.  M6 will give those a proper home.

Behaviour is preserved: all moved code is byte-for-byte identical.

include/bootstrap.h

@@ -25,14 +25,14 @@ void bootstrap_peer_ip(ssh_session session, char *ip_buf, size_t buf_size);
 
 /* pthread entry point for the per-connection bootstrap thread.
  *
- * Steps performed before handing control to client_handle_session():
+ * Steps performed before handing control to input_run_session():
  *   1. SSH key exchange
  *   2. auth (password / none / pubkey, with rate-limit feedback)
  *   3. channel open + PTY/shell-or-exec request
  *   4. construct a client_t and install its lifetime channel callbacks
  *
  * On any failure path the connection is torn down and ratelimit /
- * connection counters are released; client_handle_session() is never
+ * connection counters are released; input_run_session() is never
  * invoked.  Always returns NULL. */
 void *bootstrap_run(void *arg);
 

include/input.h

@@ -0,0 +1,31 @@
+#ifndef INPUT_H
+#define INPUT_H
+
+#include "ssh_server.h"  /* for client_t */
+
+/* Read TNT_IDLE_TIMEOUT from the environment.  Idempotent.  Call once at
+ * startup before any session can run. */
+void input_init(void);
+
+/* Run the interactive session for an already-bootstrapped client_t.
+ *
+ * Sequence:
+ *   1. If client->exec_command is set, dispatch it via exec_dispatch and
+ *      return (no chat-room join).
+ *   2. Read the desired username from the channel.
+ *   3. Add the client to g_room and broadcast a system join message.
+ *   4. Optionally show the MOTD if state-dir/motd.txt exists.
+ *   5. Drive the keyboard / room-update / keepalive / idle-timeout loop
+ *      until the client disconnects.
+ *   6. Broadcast a system leave message and release all refs / counters.
+ *
+ * Owns the client_t after entry: callers must NOT touch it once this
+ * returns.  Always returns regardless of how the session ended. */
+void input_run_session(client_t *client);
+
+/* Bell-notify any clients whose @username appears in the broadcast
+ * content, skipping the sender.  Used by the INSERT-mode send path
+ * inside input_run_session and by exec_command_post. */
+void notify_mentions(const char *content, const client_t *sender);
+
+#endif /* INPUT_H */

include/ssh_server.h

@@ -45,9 +45,6 @@ int ssh_server_init(int port);
 /* Start SSH server (blocking) */
 int ssh_server_start(int listen_fd);
 
-/* Handle client session */
-void* client_handle_session(void *arg);
-
 /* Send data to client */
 int client_send(client_t *client, const char *data, size_t len);
 
@@ -62,15 +59,10 @@ void client_release(client_t *client);
  * that target this client_t.  Caller MUST have already added one
  * client_addref() to keep the client alive across in-flight callback
  * invocations; the matching client_release() happens during cleanup in
- * client_handle_session().  Returns 0 on success, -1 on failure (in which
+ * input_run_session().  Returns 0 on success, -1 on failure (in which
  * case the caller still owns both refs and must release them). */
 int client_install_channel_callbacks(client_t *client);
 
-/* Bell-notify any clients whose @username appears in the broadcast content,
- * skipping the sender.  Defined in ssh_server.c (will move to a dedicated
- * client.c during PR2-M6). */
-void notify_mentions(const char *content, const client_t *sender);
-
 /* Read-only accessor for the server start time (used by exec stats). */
 time_t ssh_server_start_time(void);
 

src/bootstrap.c

@@ -1,5 +1,6 @@
 #include "bootstrap.h"
 #include "common.h"
+#include "input.h"
 #include "ratelimit.h"
 #include <arpa/inet.h>
 #include <errno.h>
@@ -487,6 +488,6 @@ void *bootstrap_run(void *arg) {
     }
     destroy_session_context(ctx);
 
-    client_handle_session(client);
+    input_run_session(client);
     return NULL;
 }

src/exec.c

@@ -1,6 +1,7 @@
 #include "exec.h"
 #include "chat_room.h"
 #include "common.h"
+#include "input.h"
 #include "message.h"
 #include "ratelimit.h"
 #include "utf8.h"
@@ -10,9 +11,8 @@
 #include <string.h>
 #include <time.h>
 
-/* `notify_mentions` is shared with the interactive INSERT-mode send path
+/* `notify_mentions` is shared with the interactive INSERT-mode send path.
- * (currently still in ssh_server.c, will move to its own home in PR2-M5/M6).
+ * Declared in input.h. */
- * Declared in ssh_server.h. */
 
 static void format_timestamp_utc(time_t ts, char *buffer, size_t buf_size) {
     struct tm tm_info;

src/input.c

@@ -0,0 +1,636 @@
+#include "input.h"
+#include "chat_room.h"
+#include "commands.h"
+#include "common.h"
+#include "exec.h"
+#include "message.h"
+#include "ratelimit.h"
+#include "tui.h"
+#include "utf8.h"
+#include <libssh/callbacks.h>
+#include <libssh/libssh.h>
+#include <libssh/server.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+
+static int g_idle_timeout = DEFAULT_IDLE_TIMEOUT;
+
+void input_init(void) {
+    g_idle_timeout = env_int("TNT_IDLE_TIMEOUT", DEFAULT_IDLE_TIMEOUT, 0, 86400);
+}
+
+static int read_username(client_t *client) {
+    char username[MAX_USERNAME_LEN] = {0};
+    int pos = 0;
+    char buf[4];
+
+    tui_clear_screen(client);
+    client_printf(client, "================================\r\n");
+    client_printf(client, "  欢迎来到 TNT 匿名聊天室\r\n");
+    client_printf(client, "  Welcome to TNT Anonymous Chat\r\n");
+    client_printf(client, "================================\r\n\r\n");
+    client_printf(client, "请输入用户名 (留空默认为 anonymous): ");
+
+    while (1) {
+        int n = ssh_channel_read_timeout(client->channel, buf, 1, 0, 60000); /* 60 sec timeout */
+
+        if (n == SSH_AGAIN) {
+            /* Timeout */
+            if (!ssh_channel_is_open(client->channel)) {
+                return -1;
+            }
+            continue;
+        }
+
+        if (n <= 0) return -1;
+
+        unsigned char b = buf[0];
+
+        if (b == '\r' || b == '\n') {
+            break;
+        } else if (b == 127 || b == 8) {  /* Backspace */
+            if (pos > 0) {
+                /* Compute width of the last character before removing it */
+                int old_pos = pos;
+                int ci = pos - 1;
+                while (ci > 0 && (username[ci] & 0xC0) == 0x80) ci--;
+                int bytes_read;
+                uint32_t cp = utf8_decode(username + ci, &bytes_read);
+                int w = utf8_char_width(cp);
+                utf8_remove_last_char(username);
+                pos = strlen(username);
+                (void)old_pos;
+                for (int j = 0; j < w; j++)
+                    client_printf(client, "\b \b");
+            }
+        } else if (b < 32) {
+            /* Ignore control characters */
+        } else if (b < 128) {
+            /* ASCII */
+            if (pos < MAX_USERNAME_LEN - 1) {
+                username[pos++] = b;
+                username[pos] = '\0';
+                client_send(client, (char *)&b, 1);
+            }
+        } else {
+            /* UTF-8 multi-byte */
+            int len = utf8_byte_length(b);
+            if (len <= 0 || len > 4) {
+                /* Invalid UTF-8 start byte */
+                continue;
+            }
+            buf[0] = b;
+            if (len > 1) {
+                int read_bytes = ssh_channel_read_timeout(client->channel, &buf[1], len - 1, 0, 5000);
+                if (read_bytes != len - 1) {
+                    /* Incomplete or timed-out UTF-8 continuation */
+                    continue;
+                }
+            }
+            /* Validate the complete UTF-8 sequence */
+            if (!utf8_is_valid_sequence(buf, len)) {
+                continue;
+            }
+            if (pos + len < MAX_USERNAME_LEN - 1) {
+                memcpy(username + pos, buf, len);
+                pos += len;
+                username[pos] = '\0';
+                client_send(client, buf, len);
+            }
+        }
+    }
+
+    client_printf(client, "\r\n");
+
+    if (username[0] == '\0') {
+        strncpy(client->username, "anonymous", MAX_USERNAME_LEN - 1);
+        client->username[MAX_USERNAME_LEN - 1] = '\0';
+    } else {
+        strncpy(client->username, username, MAX_USERNAME_LEN - 1);
+        client->username[MAX_USERNAME_LEN - 1] = '\0';
+
+        /* Validate username for security */
+        if (!is_valid_username(client->username)) {
+            client_printf(client, "Invalid username. Using 'anonymous' instead.\r\n");
+            strcpy(client->username, "anonymous");
+        } else {
+            /* Truncate to 20 characters */
+            if (utf8_strlen(client->username) > 20) {
+                utf8_truncate(client->username, 20);
+            }
+        }
+    }
+
+    return 0;
+}
+
+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]);
+    }
+}
+
+/* Handle a single key press.  Returns true if the key was fully consumed
+ * (no further character buffering needed). */
+static bool handle_key(client_t *client, unsigned char key, char *input) {
+    /* Handle Ctrl+C (Exit or switch to NORMAL) */
+    if (key == 3) {
+        if (client->mode != MODE_NORMAL) {
+            client->mode = MODE_NORMAL;
+            client->command_input[0] = '\0';
+            client->show_help = false;
+            tui_render_screen(client);
+        } else {
+            /* In NORMAL mode, Ctrl+C exits */
+            client->connected = false;
+        }
+        return true;
+    }
+
+    /* Handle help screen */
+    if (client->show_help) {
+        if (key == 'q' || key == 27) {
+            client->show_help = false;
+            tui_render_screen(client);
+        } else if (key == 'e' || key == 'E') {
+            client->help_lang = LANG_EN;
+            client->help_scroll_pos = 0;
+            tui_render_help(client);
+        } else if (key == 'z' || key == 'Z') {
+            client->help_lang = LANG_ZH;
+            client->help_scroll_pos = 0;
+            tui_render_help(client);
+        } else if (key == 'j') {
+            client->help_scroll_pos++;
+            tui_render_help(client);
+        } else if (key == 'k' && client->help_scroll_pos > 0) {
+            client->help_scroll_pos--;
+            tui_render_help(client);
+        } else if (key == 'g') {
+            client->help_scroll_pos = 0;
+            tui_render_help(client);
+        } else if (key == 'G') {
+            client->help_scroll_pos = 999;  /* Large number */
+            tui_render_help(client);
+        }
+        return true;  /* Key consumed */
+    }
+
+    /* Handle command output display */
+    if (client->command_output[0] != '\0') {
+        client->command_output[0] = '\0';
+        client->mode = MODE_NORMAL;
+        tui_render_screen(client);
+        return true;  /* Key consumed */
+    }
+
+    /* Mode-specific handling */
+    switch (client->mode) {
+        case MODE_INSERT:
+            if (key == 27) {  /* ESC */
+                client->mode = MODE_NORMAL;
+                client->scroll_pos = 0;
+                tui_render_screen(client);
+                return true;  /* Key consumed */
+            } else if (key == '\r' || key == '\n') {  /* Enter */
+                if (input[0] != '\0') {
+                    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';
+                }
+                tui_render_screen(client);
+                return true;  /* Key consumed */
+            } else if (key == 127 || key == 8) {  /* Backspace */
+                if (input[0] != '\0') {
+                    utf8_remove_last_char(input);
+                    tui_render_input(client, input);
+                }
+                return true;  /* Key consumed */
+            } else if (key == 23) { /* Ctrl+W (Delete Word) */
+                if (input[0] != '\0') {
+                    utf8_remove_last_word(input);
+                    tui_render_input(client, input);
+                }
+                return true;
+            } else if (key == 21) { /* Ctrl+U (Delete Line) */
+                if (input[0] != '\0') {
+                    input[0] = '\0';
+                    tui_render_input(client, input);
+                }
+                return true;
+            }
+            break;
+
+        case MODE_NORMAL: {
+            int nm_msg_count = room_get_message_count(g_room);
+            int nm_msg_height = client->height - 3;
+            if (nm_msg_height < 1) nm_msg_height = 1;
+            int nm_max_scroll = nm_msg_count - nm_msg_height;
+            if (nm_max_scroll < 0) nm_max_scroll = 0;
+
+            if (key == 'i') {
+                client->mode = MODE_INSERT;
+                tui_render_screen(client);
+                return true;
+            } else if (key == ':') {
+                client->mode = MODE_COMMAND;
+                client->command_input[0] = '\0';
+                tui_render_screen(client);
+                return true;
+            } else if (key == 'j') {
+                if (client->scroll_pos < nm_max_scroll) {
+                    client->scroll_pos++;
+                    tui_render_screen(client);
+                }
+                return true;
+            } else if (key == 'k' && client->scroll_pos > 0) {
+                client->scroll_pos--;
+                tui_render_screen(client);
+                return true;
+            } else if (key == 4) {  /* Ctrl+D: half page down */
+                int half = nm_msg_height / 2;
+                if (half < 1) half = 1;
+                client->scroll_pos += half;
+                if (client->scroll_pos > nm_max_scroll) client->scroll_pos = nm_max_scroll;
+                tui_render_screen(client);
+                return true;
+            } else if (key == 21) {  /* Ctrl+U: half page up */
+                int half = nm_msg_height / 2;
+                if (half < 1) half = 1;
+                client->scroll_pos -= half;
+                if (client->scroll_pos < 0) client->scroll_pos = 0;
+                tui_render_screen(client);
+                return true;
+            } else if (key == 6) {  /* Ctrl+F: full page down */
+                client->scroll_pos += nm_msg_height;
+                if (client->scroll_pos > nm_max_scroll) client->scroll_pos = nm_max_scroll;
+                tui_render_screen(client);
+                return true;
+            } else if (key == 2) {  /* Ctrl+B: full page up */
+                client->scroll_pos -= nm_msg_height;
+                if (client->scroll_pos < 0) client->scroll_pos = 0;
+                tui_render_screen(client);
+                return true;
+            } else if (key == 'g') {
+                client->scroll_pos = 0;
+                tui_render_screen(client);
+                return true;
+            } else if (key == 'G') {
+                client->scroll_pos = nm_max_scroll;
+                tui_render_screen(client);
+                return true;
+            } else if (key == '?') {
+                client->show_help = true;
+                client->help_scroll_pos = 0;
+                tui_render_help(client);
+                return true;
+            }
+            break;
+        }
+
+        case MODE_COMMAND:
+            if (key == 27) {  /* ESC - check for arrow key sequences */
+                char seq[2];
+                int n = ssh_channel_read_timeout(client->channel, seq, 1, 0, 50);
+                if (n == 1 && seq[0] == '[') {
+                    n = ssh_channel_read_timeout(client->channel, &seq[1], 1, 0, 50);
+                    if (n == 1) {
+                        if (seq[1] == 'A') {  /* Up arrow */
+                            if (client->command_history_count > 0 &&
+                                client->command_history_pos > 0) {
+                                client->command_history_pos--;
+                                strncpy(client->command_input,
+                                        client->command_history[client->command_history_pos],
+                                        sizeof(client->command_input) - 1);
+                                client->command_input[sizeof(client->command_input) - 1] = '\0';
+                                tui_render_screen(client);
+                            }
+                            return true;
+                        } else if (seq[1] == 'B') {  /* Down arrow */
+                            if (client->command_history_pos < client->command_history_count - 1) {
+                                client->command_history_pos++;
+                                strncpy(client->command_input,
+                                        client->command_history[client->command_history_pos],
+                                        sizeof(client->command_input) - 1);
+                                client->command_input[sizeof(client->command_input) - 1] = '\0';
+                            } else {
+                                client->command_history_pos = client->command_history_count;
+                                client->command_input[0] = '\0';
+                            }
+                            tui_render_screen(client);
+                            return true;
+                        }
+                    }
+                }
+                client->mode = MODE_NORMAL;
+                client->command_input[0] = '\0';
+                tui_render_screen(client);
+                return true;
+            } else if (key == '\r' || key == '\n') {
+                commands_dispatch(client);
+                return true;  /* Key consumed */
+            } else if (key == 127 || key == 8) {  /* Backspace */
+                if (client->command_input[0] != '\0') {
+                    utf8_remove_last_char(client->command_input);
+                    tui_render_screen(client);
+                }
+                return true;  /* Key consumed */
+            } else if (key == 23) { /* Ctrl+W (Delete Word) */
+                if (client->command_input[0] != '\0') {
+                    utf8_remove_last_word(client->command_input);
+                    tui_render_screen(client);
+                }
+                return true;
+            } else if (key == 21) { /* Ctrl+U (Delete Line) */
+                if (client->command_input[0] != '\0') {
+                    client->command_input[0] = '\0';
+                    tui_render_screen(client);
+                }
+                return true;
+            }
+            break;
+
+        default:
+            break;
+    }
+
+    return false;  /* Key not consumed */
+}
+
+void input_run_session(client_t *client) {
+    char input[MAX_MESSAGE_LEN] = {0};
+    char buf[4];
+    bool joined_room = false;
+    uint64_t seen_update_seq;
+    time_t last_keepalive = time(NULL);
+
+    /* Terminal size already set from PTY request */
+    client->mode = MODE_INSERT;
+    client->help_lang = LANG_ZH;
+    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') {
+        int exit_status = exec_dispatch(client);
+        ssh_channel_request_send_exit_status(client->channel, exit_status);
+        goto cleanup;
+    }
+
+    /* Read username */
+    if (read_username(client) < 0) {
+        goto cleanup;
+    }
+
+    /* Add to room */
+    if (room_add_client(g_room, client) < 0) {
+        client_printf(client, "Room is full\n");
+        goto cleanup;
+    }
+    joined_room = true;
+
+    /* Broadcast join message */
+    message_t join_msg = {
+        .timestamp = time(NULL),
+    };
+    strncpy(join_msg.username, "系统", MAX_USERNAME_LEN - 1);
+    join_msg.username[MAX_USERNAME_LEN - 1] = '\0';
+    snprintf(join_msg.content, MAX_MESSAGE_LEN, "%s 加入了聊天室", client->username);
+    room_broadcast(g_room, &join_msg);
+    message_save(&join_msg);
+
+    /* Show MOTD if motd.txt exists in state directory */
+    {
+        char motd_path[PATH_MAX];
+        if (tnt_state_path(motd_path, sizeof(motd_path), "motd.txt") == 0) {
+            FILE *motd_fp = fopen(motd_path, "r");
+            if (motd_fp) {
+                char motd_buf[sizeof(client->command_output) - 64];
+                size_t motd_len = fread(motd_buf, 1, sizeof(motd_buf) - 1, motd_fp);
+                fclose(motd_fp);
+                if (motd_len > 0) {
+                    motd_buf[motd_len] = '\0';
+                    snprintf(client->command_output, sizeof(client->command_output),
+                             "=== 公告 / MOTD ===\n%s", motd_buf);
+                    tui_render_command_output(client);
+                    seen_update_seq = room_get_update_seq(g_room);
+                    goto main_loop;
+                }
+            }
+        }
+    }
+
+    /* Render initial screen */
+    tui_render_screen(client);
+    seen_update_seq = room_get_update_seq(g_room);
+
+main_loop:
+
+    /* Main input loop */
+    while (client->connected && ssh_channel_is_open(client->channel)) {
+        int ready = ssh_channel_poll_timeout(client->channel, 1000, 0);
+
+        if (ready == SSH_ERROR) {
+            break;
+        }
+
+        if (ready == 0) {
+            bool room_updated = false;
+            uint64_t current_update_seq = room_get_update_seq(g_room);
+
+            if (!ssh_channel_is_open(client->channel)) {
+                break;
+            }
+
+            if (current_update_seq != seen_update_seq) {
+                seen_update_seq = current_update_seq;
+                room_updated = true;
+            }
+
+            if (client->redraw_pending ||
+                (room_updated && !client->show_help &&
+                 client->command_output[0] == '\0')) {
+                client->redraw_pending = false;
+
+                if (client->show_help) {
+                    tui_render_help(client);
+                } else if (client->command_output[0] != '\0') {
+                    tui_render_command_output(client);
+                } else {
+                    tui_render_screen(client);
+                    if (client->mode == MODE_INSERT && input[0] != '\0') {
+                        tui_render_input(client, input);
+                    }
+                }
+            } else if (time(NULL) - last_keepalive >= 15) {
+                if (ssh_send_keepalive(client->session) != SSH_OK) {
+                    break;
+                }
+                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;
+        }
+
+        int n = ssh_channel_read(client->channel, buf, 1, 0);
+
+        if (n <= 0) {
+            /* EOF or error */
+            break;
+        }
+
+        last_keepalive = time(NULL);
+        client->last_active = last_keepalive;
+
+        unsigned char b = buf[0];
+
+        /* Handle special keys - returns true if key was consumed */
+        bool key_consumed = handle_key(client, b, input);
+
+        /* Only add character to input if not consumed by handle_key */
+        if (!key_consumed) {
+            /* Add character to input (INSERT mode only) */
+            if (client->mode == MODE_INSERT && !client->show_help &&
+                client->command_output[0] == '\0') {
+                if (b >= 32 && b < 127) {  /* ASCII printable */
+                    int len = strlen(input);
+                    if (len < MAX_MESSAGE_LEN - 1) {
+                        input[len] = b;
+                        input[len + 1] = '\0';
+                        tui_render_input(client, input);
+                    }
+                } else if (b >= 128) {  /* UTF-8 multi-byte */
+                    int char_len = utf8_byte_length(b);
+                    if (char_len <= 0 || char_len > 4) {
+                        /* Invalid UTF-8 start byte */
+                        continue;
+                    }
+                    buf[0] = b;
+                    if (char_len > 1) {
+                        int read_bytes = ssh_channel_read_timeout(client->channel, &buf[1], char_len - 1, 0, 5000);
+                        if (read_bytes != char_len - 1) {
+                            /* Incomplete or timed-out UTF-8 continuation */
+                            continue;
+                        }
+                    }
+                    /* Validate the complete UTF-8 sequence */
+                    if (!utf8_is_valid_sequence(buf, char_len)) {
+                        /* Invalid UTF-8 sequence */
+                        continue;
+                    }
+                    int len = strlen(input);
+                    if (len + char_len < MAX_MESSAGE_LEN - 1) {
+                        memcpy(input + len, buf, char_len);
+                        input[len + char_len] = '\0';
+                        tui_render_input(client, input);
+                    }
+                }
+            } else if (client->mode == MODE_COMMAND && !client->show_help &&
+                       client->command_output[0] == '\0') {
+                if (b >= 32 && b < 127) {  /* ASCII printable */
+                    size_t len = strlen(client->command_input);
+                    if (len < sizeof(client->command_input) - 1) {
+                        client->command_input[len] = b;
+                        client->command_input[len + 1] = '\0';
+                        tui_render_screen(client);
+                    }
+                } else if (b >= 128) {  /* UTF-8 multi-byte */
+                    int char_len = utf8_byte_length(b);
+                    if (char_len <= 0 || char_len > 4) continue;
+                    buf[0] = b;
+                    if (char_len > 1) {
+                        int read_bytes = ssh_channel_read_timeout(
+                            client->channel, &buf[1], char_len - 1, 0, 5000);
+                        if (read_bytes != char_len - 1) continue;
+                    }
+                    if (!utf8_is_valid_sequence(buf, char_len)) continue;
+                    size_t len = strlen(client->command_input);
+                    if (len + (size_t)char_len < sizeof(client->command_input) - 1) {
+                        memcpy(client->command_input + len, buf, char_len);
+                        client->command_input[len + char_len] = '\0';
+                        tui_render_screen(client);
+                    }
+                }
+            }
+        }
+    }
+
+cleanup:
+    /* Broadcast leave message */
+    if (joined_room) {
+        message_t leave_msg = {
+            .timestamp = time(NULL),
+        };
+        strncpy(leave_msg.username, "系统", MAX_USERNAME_LEN - 1);
+        leave_msg.username[MAX_USERNAME_LEN - 1] = '\0';
+        snprintf(leave_msg.content, MAX_MESSAGE_LEN, "%s 离开了聊天室", client->username);
+
+        client->connected = false;
+        room_remove_client(g_room, client);
+        room_broadcast(g_room, &leave_msg);
+        message_save(&leave_msg);
+    }
+
+    ratelimit_release_ip(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 client_install_channel_callbacks) */
+    client_release(client);
+
+    /* Release the main reference - client will be freed when all refs are gone */
+    client_release(client);
+
+    /* Decrement connection count */
+    ratelimit_decrement_total();
+}

src/ssh_server.c

@@ -2,6 +2,7 @@
 #include "bootstrap.h"
 #include "commands.h"
 #include "exec.h"
+#include "input.h"
 #include "ratelimit.h"
 #include "tui.h"
 #include "utf8.h"
@@ -29,10 +30,8 @@ time_t ssh_server_start_time(void) {
     return g_server_start_time;
 }
 
-/* Configuration from environment variables.  Rate-limiting moved to ratelimit.{c,h}
+/* Configuration from environment variables.  Rate-limiting moved to ratelimit.{c,h},
- * and the access token now lives in bootstrap.{c,h}; the idle timeout stays here
+ * the access token to bootstrap.{c,h}, and the idle timeout to input.{c,h}. */
- * until input.c is extracted in PR2-M5. */
-static int g_idle_timeout = DEFAULT_IDLE_TIMEOUT;
 
 /* Generate or load SSH host key */
 static int setup_host_key(ssh_bind sshbind) {
@@ -204,630 +203,6 @@ int client_printf(client_t *client, const char *fmt, ...) {
     return client_send(client, buffer, len);
 }
 
-/* Read username from client */
-static int read_username(client_t *client) {
-    char username[MAX_USERNAME_LEN] = {0};
-    int pos = 0;
-    char buf[4];
-
-    tui_clear_screen(client);
-    client_printf(client, "================================\r\n");
-    client_printf(client, "  欢迎来到 TNT 匿名聊天室\r\n");
-    client_printf(client, "  Welcome to TNT Anonymous Chat\r\n");
-    client_printf(client, "================================\r\n\r\n");
-    client_printf(client, "请输入用户名 (留空默认为 anonymous): ");
-
-    while (1) {
-        int n = ssh_channel_read_timeout(client->channel, buf, 1, 0, 60000); /* 60 sec timeout */
-
-        if (n == SSH_AGAIN) {
-            /* Timeout */
-            if (!ssh_channel_is_open(client->channel)) {
-                return -1;
-            }
-            continue;
-        }
-
-        if (n <= 0) return -1;
-
-        unsigned char b = buf[0];
-
-        if (b == '\r' || b == '\n') {
-            break;
-        } else if (b == 127 || b == 8) {  /* Backspace */
-            if (pos > 0) {
-                /* Compute width of the last character before removing it */
-                int old_pos = pos;
-                int ci = pos - 1;
-                while (ci > 0 && (username[ci] & 0xC0) == 0x80) ci--;
-                int bytes_read;
-                uint32_t cp = utf8_decode(username + ci, &bytes_read);
-                int w = utf8_char_width(cp);
-                utf8_remove_last_char(username);
-                pos = strlen(username);
-                (void)old_pos;
-                for (int j = 0; j < w; j++)
-                    client_printf(client, "\b \b");
-            }
-        } else if (b < 32) {
-            /* Ignore control characters */
-        } else if (b < 128) {
-            /* ASCII */
-            if (pos < MAX_USERNAME_LEN - 1) {
-                username[pos++] = b;
-                username[pos] = '\0';
-                client_send(client, (char *)&b, 1);
-            }
-        } else {
-            /* UTF-8 multi-byte */
-            int len = utf8_byte_length(b);
-            if (len <= 0 || len > 4) {
-                /* Invalid UTF-8 start byte */
-                continue;
-            }
-            buf[0] = b;
-            if (len > 1) {
-                int read_bytes = ssh_channel_read_timeout(client->channel, &buf[1], len - 1, 0, 5000);
-                if (read_bytes != len - 1) {
-                    /* Incomplete or timed-out UTF-8 continuation */
-                    continue;
-                }
-            }
-            /* Validate the complete UTF-8 sequence */
-            if (!utf8_is_valid_sequence(buf, len)) {
-                continue;
-            }
-            if (pos + len < MAX_USERNAME_LEN - 1) {
-                memcpy(username + pos, buf, len);
-                pos += len;
-                username[pos] = '\0';
-                client_send(client, buf, len);
-            }
-        }
-    }
-
-    client_printf(client, "\r\n");
-
-    if (username[0] == '\0') {
-        strncpy(client->username, "anonymous", MAX_USERNAME_LEN - 1);
-        client->username[MAX_USERNAME_LEN - 1] = '\0';
-    } else {
-        strncpy(client->username, username, MAX_USERNAME_LEN - 1);
-        client->username[MAX_USERNAME_LEN - 1] = '\0';
-
-        /* Validate username for security */
-        if (!is_valid_username(client->username)) {
-            client_printf(client, "Invalid username. Using 'anonymous' instead.\r\n");
-            strcpy(client->username, "anonymous");
-        } else {
-            /* Truncate to 20 characters */
-            if (utf8_strlen(client->username) > 20) {
-                utf8_truncate(client->username, 20);
-            }
-        }
-    }
-
-    return 0;
-}
-
-/* Notify any clients whose usernames appear as @mentions in `content`.
- * Lives here because it bridges chat_room (target lookup) and the client
- * I/O API; will move into a proper home when a `client.c` is carved out
- * during PR2-M6 server cleanup. */
-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]);
-    }
-}
-
-/* Execute a command */
-
-/* Handle client key press - returns true if key was consumed */
-static bool handle_key(client_t *client, unsigned char key, char *input) {
-    /* Handle Ctrl+C (Exit or switch to NORMAL) */
-    if (key == 3) {
-        if (client->mode != MODE_NORMAL) {
-            client->mode = MODE_NORMAL;
-            client->command_input[0] = '\0';
-            client->show_help = false;
-            tui_render_screen(client);
-        } else {
-            /* In NORMAL mode, Ctrl+C exits */
-            client->connected = false;
-        }
-        return true;
-    }
-
-    /* Handle help screen */
-    if (client->show_help) {
-        if (key == 'q' || key == 27) {
-            client->show_help = false;
-            tui_render_screen(client);
-        } else if (key == 'e' || key == 'E') {
-            client->help_lang = LANG_EN;
-            client->help_scroll_pos = 0;
-            tui_render_help(client);
-        } else if (key == 'z' || key == 'Z') {
-            client->help_lang = LANG_ZH;
-            client->help_scroll_pos = 0;
-            tui_render_help(client);
-        } else if (key == 'j') {
-            client->help_scroll_pos++;
-            tui_render_help(client);
-        } else if (key == 'k' && client->help_scroll_pos > 0) {
-            client->help_scroll_pos--;
-            tui_render_help(client);
-        } else if (key == 'g') {
-            client->help_scroll_pos = 0;
-            tui_render_help(client);
-        } else if (key == 'G') {
-            client->help_scroll_pos = 999;  /* Large number */
-            tui_render_help(client);
-        }
-        return true;  /* Key consumed */
-    }
-
-    /* Handle command output display */
-    if (client->command_output[0] != '\0') {
-        client->command_output[0] = '\0';
-        client->mode = MODE_NORMAL;
-        tui_render_screen(client);
-        return true;  /* Key consumed */
-    }
-
-    /* Mode-specific handling */
-    switch (client->mode) {
-        case MODE_INSERT:
-            if (key == 27) {  /* ESC */
-                client->mode = MODE_NORMAL;
-                client->scroll_pos = 0;
-                tui_render_screen(client);
-                return true;  /* Key consumed */
-            } else if (key == '\r' || key == '\n') {  /* Enter */
-                if (input[0] != '\0') {
-                    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';
-                }
-                tui_render_screen(client);
-                return true;  /* Key consumed */
-            } else if (key == 127 || key == 8) {  /* Backspace */
-                if (input[0] != '\0') {
-                    utf8_remove_last_char(input);
-                    tui_render_input(client, input);
-                }
-                return true;  /* Key consumed */
-            } else if (key == 23) { /* Ctrl+W (Delete Word) */
-                if (input[0] != '\0') {
-                    utf8_remove_last_word(input);
-                    tui_render_input(client, input);
-                }
-                return true;
-            } else if (key == 21) { /* Ctrl+U (Delete Line) */
-                if (input[0] != '\0') {
-                    input[0] = '\0';
-                    tui_render_input(client, input);
-                }
-                return true;
-            }
-            break;
-
-        case MODE_NORMAL: {
-            int nm_msg_count = room_get_message_count(g_room);
-            int nm_msg_height = client->height - 3;
-            if (nm_msg_height < 1) nm_msg_height = 1;
-            int nm_max_scroll = nm_msg_count - nm_msg_height;
-            if (nm_max_scroll < 0) nm_max_scroll = 0;
-
-            if (key == 'i') {
-                client->mode = MODE_INSERT;
-                tui_render_screen(client);
-                return true;
-            } else if (key == ':') {
-                client->mode = MODE_COMMAND;
-                client->command_input[0] = '\0';
-                tui_render_screen(client);
-                return true;
-            } else if (key == 'j') {
-                if (client->scroll_pos < nm_max_scroll) {
-                    client->scroll_pos++;
-                    tui_render_screen(client);
-                }
-                return true;
-            } else if (key == 'k' && client->scroll_pos > 0) {
-                client->scroll_pos--;
-                tui_render_screen(client);
-                return true;
-            } else if (key == 4) {  /* Ctrl+D: half page down */
-                int half = nm_msg_height / 2;
-                if (half < 1) half = 1;
-                client->scroll_pos += half;
-                if (client->scroll_pos > nm_max_scroll) client->scroll_pos = nm_max_scroll;
-                tui_render_screen(client);
-                return true;
-            } else if (key == 21) {  /* Ctrl+U: half page up */
-                int half = nm_msg_height / 2;
-                if (half < 1) half = 1;
-                client->scroll_pos -= half;
-                if (client->scroll_pos < 0) client->scroll_pos = 0;
-                tui_render_screen(client);
-                return true;
-            } else if (key == 6) {  /* Ctrl+F: full page down */
-                client->scroll_pos += nm_msg_height;
-                if (client->scroll_pos > nm_max_scroll) client->scroll_pos = nm_max_scroll;
-                tui_render_screen(client);
-                return true;
-            } else if (key == 2) {  /* Ctrl+B: full page up */
-                client->scroll_pos -= nm_msg_height;
-                if (client->scroll_pos < 0) client->scroll_pos = 0;
-                tui_render_screen(client);
-                return true;
-            } else if (key == 'g') {
-                client->scroll_pos = 0;
-                tui_render_screen(client);
-                return true;
-            } else if (key == 'G') {
-                client->scroll_pos = nm_max_scroll;
-                tui_render_screen(client);
-                return true;
-            } else if (key == '?') {
-                client->show_help = true;
-                client->help_scroll_pos = 0;
-                tui_render_help(client);
-                return true;
-            }
-            break;
-        }
-
-        case MODE_COMMAND:
-            if (key == 27) {  /* ESC - check for arrow key sequences */
-                char seq[2];
-                int n = ssh_channel_read_timeout(client->channel, seq, 1, 0, 50);
-                if (n == 1 && seq[0] == '[') {
-                    n = ssh_channel_read_timeout(client->channel, &seq[1], 1, 0, 50);
-                    if (n == 1) {
-                        if (seq[1] == 'A') {  /* Up arrow */
-                            if (client->command_history_count > 0 &&
-                                client->command_history_pos > 0) {
-                                client->command_history_pos--;
-                                strncpy(client->command_input,
-                                        client->command_history[client->command_history_pos],
-                                        sizeof(client->command_input) - 1);
-                                client->command_input[sizeof(client->command_input) - 1] = '\0';
-                                tui_render_screen(client);
-                            }
-                            return true;
-                        } else if (seq[1] == 'B') {  /* Down arrow */
-                            if (client->command_history_pos < client->command_history_count - 1) {
-                                client->command_history_pos++;
-                                strncpy(client->command_input,
-                                        client->command_history[client->command_history_pos],
-                                        sizeof(client->command_input) - 1);
-                                client->command_input[sizeof(client->command_input) - 1] = '\0';
-                            } else {
-                                client->command_history_pos = client->command_history_count;
-                                client->command_input[0] = '\0';
-                            }
-                            tui_render_screen(client);
-                            return true;
-                        }
-                    }
-                }
-                client->mode = MODE_NORMAL;
-                client->command_input[0] = '\0';
-                tui_render_screen(client);
-                return true;
-            } else if (key == '\r' || key == '\n') {
-                commands_dispatch(client);
-                return true;  /* Key consumed */
-            } else if (key == 127 || key == 8) {  /* Backspace */
-                if (client->command_input[0] != '\0') {
-                    utf8_remove_last_char(client->command_input);
-                    tui_render_screen(client);
-                }
-                return true;  /* Key consumed */
-            } else if (key == 23) { /* Ctrl+W (Delete Word) */
-                if (client->command_input[0] != '\0') {
-                    utf8_remove_last_word(client->command_input);
-                    tui_render_screen(client);
-                }
-                return true;
-            } else if (key == 21) { /* Ctrl+U (Delete Line) */
-                if (client->command_input[0] != '\0') {
-                    client->command_input[0] = '\0';
-                    tui_render_screen(client);
-                }
-                return true;
-            }
-            break;
-
-        default:
-            break;
-    }
-
-    return false;  /* Key not consumed */
-}
-
-/* Handle client session */
-void* client_handle_session(void *arg) {
-    client_t *client = (client_t*)arg;
-    char input[MAX_MESSAGE_LEN] = {0};
-    char buf[4];
-    bool joined_room = false;
-    uint64_t seen_update_seq;
-    time_t last_keepalive = time(NULL);
-
-    /* Terminal size already set from PTY request */
-    client->mode = MODE_INSERT;
-    client->help_lang = LANG_ZH;
-    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') {
-        int exit_status = exec_dispatch(client);
-        ssh_channel_request_send_exit_status(client->channel, exit_status);
-        goto cleanup;
-    }
-
-    /* Read username */
-    if (read_username(client) < 0) {
-        goto cleanup;
-    }
-
-    /* Add to room */
-    if (room_add_client(g_room, client) < 0) {
-        client_printf(client, "Room is full\n");
-        goto cleanup;
-    }
-    joined_room = true;
-
-    /* Broadcast join message */
-    message_t join_msg = {
-        .timestamp = time(NULL),
-    };
-    strncpy(join_msg.username, "系统", MAX_USERNAME_LEN - 1);
-    join_msg.username[MAX_USERNAME_LEN - 1] = '\0';
-    snprintf(join_msg.content, MAX_MESSAGE_LEN, "%s 加入了聊天室", client->username);
-    room_broadcast(g_room, &join_msg);
-    message_save(&join_msg);
-
-    /* Show MOTD if motd.txt exists in state directory */
-    {
-        char motd_path[PATH_MAX];
-        if (tnt_state_path(motd_path, sizeof(motd_path), "motd.txt") == 0) {
-            FILE *motd_fp = fopen(motd_path, "r");
-            if (motd_fp) {
-                char motd_buf[sizeof(client->command_output) - 64];
-                size_t motd_len = fread(motd_buf, 1, sizeof(motd_buf) - 1, motd_fp);
-                fclose(motd_fp);
-                if (motd_len > 0) {
-                    motd_buf[motd_len] = '\0';
-                    snprintf(client->command_output, sizeof(client->command_output),
-                             "=== 公告 / MOTD ===\n%s", motd_buf);
-                    tui_render_command_output(client);
-                    seen_update_seq = room_get_update_seq(g_room);
-                    goto main_loop;
-                }
-            }
-        }
-    }
-
-    /* Render initial screen */
-    tui_render_screen(client);
-    seen_update_seq = room_get_update_seq(g_room);
-
-main_loop:
-
-    /* Main input loop */
-    while (client->connected && ssh_channel_is_open(client->channel)) {
-        int ready = ssh_channel_poll_timeout(client->channel, 1000, 0);
-
-        if (ready == SSH_ERROR) {
-            break;
-        }
-
-        if (ready == 0) {
-            bool room_updated = false;
-            uint64_t current_update_seq = room_get_update_seq(g_room);
-
-            if (!ssh_channel_is_open(client->channel)) {
-                break;
-            }
-
-            if (current_update_seq != seen_update_seq) {
-                seen_update_seq = current_update_seq;
-                room_updated = true;
-            }
-
-            if (client->redraw_pending ||
-                (room_updated && !client->show_help &&
-                 client->command_output[0] == '\0')) {
-                client->redraw_pending = false;
-
-                if (client->show_help) {
-                    tui_render_help(client);
-                } else if (client->command_output[0] != '\0') {
-                    tui_render_command_output(client);
-                } else {
-                    tui_render_screen(client);
-                    if (client->mode == MODE_INSERT && input[0] != '\0') {
-                        tui_render_input(client, input);
-                    }
-                }
-            } else if (time(NULL) - last_keepalive >= 15) {
-                if (ssh_send_keepalive(client->session) != SSH_OK) {
-                    break;
-                }
-                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;
-        }
-
-        int n = ssh_channel_read(client->channel, buf, 1, 0);
-
-        if (n <= 0) {
-            /* EOF or error */
-            break;
-        }
-
-        last_keepalive = time(NULL);
-        client->last_active = last_keepalive;
-
-        unsigned char b = buf[0];
-
-        /* Handle special keys - returns true if key was consumed */
-        bool key_consumed = handle_key(client, b, input);
-
-        /* Only add character to input if not consumed by handle_key */
-        if (!key_consumed) {
-            /* Add character to input (INSERT mode only) */
-            if (client->mode == MODE_INSERT && !client->show_help &&
-                client->command_output[0] == '\0') {
-                if (b >= 32 && b < 127) {  /* ASCII printable */
-                    int len = strlen(input);
-                    if (len < MAX_MESSAGE_LEN - 1) {
-                        input[len] = b;
-                        input[len + 1] = '\0';
-                        tui_render_input(client, input);
-                    }
-                } else if (b >= 128) {  /* UTF-8 multi-byte */
-                    int char_len = utf8_byte_length(b);
-                    if (char_len <= 0 || char_len > 4) {
-                        /* Invalid UTF-8 start byte */
-                        continue;
-                    }
-                    buf[0] = b;
-                    if (char_len > 1) {
-                        int read_bytes = ssh_channel_read_timeout(client->channel, &buf[1], char_len - 1, 0, 5000);
-                        if (read_bytes != char_len - 1) {
-                            /* Incomplete or timed-out UTF-8 continuation */
-                            continue;
-                        }
-                    }
-                    /* Validate the complete UTF-8 sequence */
-                    if (!utf8_is_valid_sequence(buf, char_len)) {
-                        /* Invalid UTF-8 sequence */
-                        continue;
-                    }
-                    int len = strlen(input);
-                    if (len + char_len < MAX_MESSAGE_LEN - 1) {
-                        memcpy(input + len, buf, char_len);
-                        input[len + char_len] = '\0';
-                        tui_render_input(client, input);
-                    }
-                }
-            } else if (client->mode == MODE_COMMAND && !client->show_help &&
-                       client->command_output[0] == '\0') {
-                if (b >= 32 && b < 127) {  /* ASCII printable */
-                    size_t len = strlen(client->command_input);
-                    if (len < sizeof(client->command_input) - 1) {
-                        client->command_input[len] = b;
-                        client->command_input[len + 1] = '\0';
-                        tui_render_screen(client);
-                    }
-                } else if (b >= 128) {  /* UTF-8 multi-byte */
-                    int char_len = utf8_byte_length(b);
-                    if (char_len <= 0 || char_len > 4) continue;
-                    buf[0] = b;
-                    if (char_len > 1) {
-                        int read_bytes = ssh_channel_read_timeout(
-                            client->channel, &buf[1], char_len - 1, 0, 5000);
-                        if (read_bytes != char_len - 1) continue;
-                    }
-                    if (!utf8_is_valid_sequence(buf, char_len)) continue;
-                    size_t len = strlen(client->command_input);
-                    if (len + (size_t)char_len < sizeof(client->command_input) - 1) {
-                        memcpy(client->command_input + len, buf, char_len);
-                        client->command_input[len + char_len] = '\0';
-                        tui_render_screen(client);
-                    }
-                }
-            }
-        }
-    }
-
-cleanup:
-    /* Broadcast leave message */
-    if (joined_room) {
-        message_t leave_msg = {
-            .timestamp = time(NULL),
-        };
-        strncpy(leave_msg.username, "系统", MAX_USERNAME_LEN - 1);
-        leave_msg.username[MAX_USERNAME_LEN - 1] = '\0';
-        snprintf(leave_msg.content, MAX_MESSAGE_LEN, "%s 离开了聊天室", client->username);
-
-        client->connected = false;
-        room_remove_client(g_room, client);
-        room_broadcast(g_room, &leave_msg);
-        message_save(&leave_msg);
-    }
-
-    ratelimit_release_ip(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 client_install_channel_callbacks) */
-    client_release(client);
-
-    /* Release the main reference - client will be freed when all refs are gone */
-    client_release(client);
-
-    /* Decrement connection count */
-    ratelimit_decrement_total();
-
-    return NULL;
-}
-
 static int client_channel_window_change(ssh_session session, ssh_channel channel,
                                         int width, int height,
                                         int pxwidth, int pxheight,
@@ -909,7 +284,8 @@ int ssh_server_init(int port) {
     bootstrap_init();
 
     /* Idle timeout stays here until input.c is extracted in PR2-M5 */
-    g_idle_timeout = env_int("TNT_IDLE_TIMEOUT", DEFAULT_IDLE_TIMEOUT, 0, 86400);
+    /* Initialize idle-timeout subsystem */
+    input_init();
     g_listen_port = port;
     g_server_start_time = time(NULL);