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fix: CJK backspace display, UTF-8 in command mode, auth timeout

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- Fix backspace in read_username to erase correct display width for
  CJK/wide characters (was erasing only 1 column for 2-column chars)
- Add UTF-8 multi-byte input support in COMMAND mode (was silently
  dropping non-ASCII bytes, breaking CJK command arguments)
- Reduce SSH auth timeout from 30s to 10s to limit connection-slot
  exhaustion from slow/malicious handshakes
This commit is contained in:
m1ngsama 2026-04-19 16:19:43 +08:00
parent 0de13a6314
commit 9607d8c2f2
1 changed files with 27 additions and 2 deletions
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29
src/ssh_server.c
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@ -584,9 +584,18 @@ static int read_username(client_t *client) {
break; break;
} else if (b == 127 || b == 8) { /* Backspace */ } else if (b == 127 || b == 8) { /* Backspace */
if (pos > 0) { 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); utf8_remove_last_char(username);
pos = strlen(username); pos = strlen(username);
client_printf(client, "\b \b"); (void)old_pos;
for (int j = 0; j < w; j++)
client_printf(client, "\b \b");
} }
} else if (b < 32) { } else if (b < 32) {
/* Ignore control characters */ /* Ignore control characters */
@ -1478,6 +1487,22 @@ void* client_handle_session(void *arg) {
client->command_input[len + 1] = '\0'; client->command_input[len + 1] = '\0';
tui_render_screen(client); 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);
}
} }
} }
} }
@ -1911,7 +1936,7 @@ static void *bootstrap_client_session(void *arg) {
break; break;
} }
if (time(NULL) - start_time > 30) { if (time(NULL) - start_time > 10) {
timed_out = true; timed_out = true;
} }
} }