fedserv/echoIRCd
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mode: cap mode changes per MODE command (modes=, default 20) and advertise it as the MODES= ISUPPORT token — an uncapped modestring like MODE #c +bbbb… dispatched a handler per letter, each fanning out to the whole channel and every S2S link (amplification DoS); matches InspIRCd's MODES limit

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This commit is contained in:
Jean Chevronnet 2026-08-19 00:40:58 +00:00
parent 11cec9fc36
commit c72b966e0a
2 changed files with 11 additions and 1 deletions
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9
src/coremods/core_mode.rs
View file

@ -119,11 +119,20 @@ pub fn apply_mode(s: &mut Server, uid: Uid, params: &[String]) -> CmdResult {
let mut echoed: Vec<String> = Vec::new();
// (sign, letter, displayed-param) per applied change — for hidemode filtering
let mut changes: Vec<(char, char, Option<String>)> = Vec::new();
// Cap mode changes per command (advertised as MODES=, default 20 like InspIRCd):
// otherwise `MODE #c +bbbb…` in one line dispatches hundreds of handlers, each
// fanning out to the whole channel and every link — a cheap amplification flood.
let max_modes = s.conf_num("modes", 20usize).max(1);
let mut processed = 0usize;
for c in modestring.chars() {
if c == '+' || c == '-' {
sign = c;
continue;
}
if processed >= max_modes {
break;
}
processed += 1;
let adding = sign == '+';
let Some(handler) = chan_mode(c) else {
s.numeric(

3
src/server.rs
View file

@ -771,12 +771,13 @@ impl Server {
let chathist = crate::modules::chathistory::limit(self);
let maxnick = self.conf_num("maxnick", 30usize);
let maxchan = self.conf_num("maxchannel", 50usize);
let maxmodes = self.conf_num("modes", 20usize).max(1);
// operprefix/ojoin add the server oper prefix `y` above owner; sigils are
// config-overridable (see modules::customprefix)
let include_oper = self.conf_bool("operprefix", false) || self.conf_bool("ojoin", false);
let prefix = crate::modules::customprefix::isupport(include_oper);
let mut tokens: Vec<String> = format!(
"CHANTYPES=# PREFIX={prefix} CHANMODES=beIgXw,k,lfjFLHBJdK,ACDGMNOPQRSTUcimnprstuz EXTBAN=,aGbcgjmnrsy ACCOUNTEXTBAN=a BOT=B WATCH={maxwatch} MONITOR={maxmon} SILENCE={maxsil} CALLERID=g WHOX CHATHISTORY={chathist} MSGREFTYPES=timestamp,msgid UTF8ONLY CASEMAPPING=ascii NICKLEN={maxnick} CHANNELLEN={maxchan} NETWORK={}",
"CHANTYPES=# PREFIX={prefix} CHANMODES=beIgXw,k,lfjFLHBJdK,ACDGMNOPQRSTUcimnprstuz EXTBAN=,aGbcgjmnrsy ACCOUNTEXTBAN=a BOT=B WATCH={maxwatch} MONITOR={maxmon} SILENCE={maxsil} CALLERID=g WHOX CHATHISTORY={chathist} MSGREFTYPES=timestamp,msgid UTF8ONLY CASEMAPPING=ascii NICKLEN={maxnick} CHANNELLEN={maxchan} MODES={maxmodes} NETWORK={}",
self.network
)
.split(' ')