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feat: add support for packetLoss on localhost #99

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finger563 wants to merge 5 commits into from
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feat: add support for packetLoss on localhost #99

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20267aa
feat: Add support for `packetLoss` on localhost
finger563 Aug 6, 2025
4d2f08d
Merge branch 'main' into main
soulgalore Mar 23, 2026
ee7e656
Merge branch 'main' into main
soulgalore Mar 23, 2026
09b0544
Merge branch 'main' into main
soulgalore Mar 23, 2026
2329bd6
Merge branch 'main' into main
soulgalore Mar 23, 2026
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2 changes: 1 addition & 1 deletion bin/index.js
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Original file line number Diff line number Diff line change
Expand Up @@ -150,7 +150,7 @@
try {
await start(options);
if (options.localhost) {
console.log(`Started throttler on localhost RTT:${options.rtt}ms `);
console.log(`Started throttler on localhost RTT:${options.rtt}ms PL:${options.packetLoss}%`);

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GitHub Actions / build (22.x) 

Replace ``Started·throttler·on·localhost·RTT:${options.rtt}ms·PL:${options.packetLoss}%`` with `⏎············`Started·throttler·on·localhost·RTT:${options.rtt}ms·PL:${options.packetLoss}%`⏎··········`
} else {
let message = 'Started throttler:';
if (typeof options.down !== 'undefined') {
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4 changes: 2 additions & 2 deletions lib/index.js
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Original file line number Diff line number Diff line change
Expand Up @@ -32,7 +32,7 @@ export async function start(options = {}) {
switch (platform()) {
case 'darwin': {
if (options.localhost) {
return startPfctlLocalhost(options.rtt);
return startPfctlLocalhost(options.rtt, options.packetLoss);
}
return startPfctl(
options.up,
Expand All @@ -44,7 +44,7 @@ export async function start(options = {}) {

case 'linux': {
return options.localhost
? startTcLocalhost(options.rtt)
? startTcLocalhost(options.rtt, options.packetLoss)
: startTc(options.up, options.down, options.rtt, options.packetLoss);
}

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13 changes: 8 additions & 5 deletions lib/localHostPfctl.js
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Original file line number Diff line number Diff line change
@@ -1,23 +1,26 @@
import sudo from './sudo.js';
import shell from './shell.js';

export async function start(rtt) {
export async function start(rtt, packetLoss=0) {

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Replace `=` with `·=·`
const halfWayRTT = rtt / 2;

await stop();

await sudo('dnctl', '-q', 'flush');
await sudo('dnctl', '-q', 'pipe', 'flush');

await sudo(
const parameters = [

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Replace `⏎····'dnctl',⏎····'pipe',⏎····1,⏎····'config',⏎····'delay',⏎····`${halfWayRTT}ms`⏎··` with `'dnctl',·'pipe',·1,·'config',·'delay',·`${halfWayRTT}ms``
'dnctl',
'pipe',
1,
'config',
'delay',
`${halfWayRTT}ms`,
'noerror'
);
`${halfWayRTT}ms`
];
if (packetLoss > 0) {
parameters.push('plr', packetLoss / 100, 'noerror');
}
await sudo.apply(this, parameters);

await shell(
'echo "dummynet out from any to 127.0.0.1 pipe 1" | sudo pfctl -f -'
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12 changes: 9 additions & 3 deletions lib/localHostTc.js
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Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
import sudo from './sudo.js';

export async function start(delay) {
export async function start(delay, packetLoss=0) {

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Replace `=` with `·=·`
const halfWayDelay = delay / 2;

try {
Expand All @@ -9,7 +9,7 @@
// ignore
}

await sudo(
const parameters = [
'tc',
'qdisc',
'add',
Expand All @@ -21,7 +21,13 @@
'netem',
'delay',
`${halfWayDelay}ms`
);
];

if (packetLoss) {
parameters.push('loss', `${packetLoss}%`);
}

await sudo.apply(this, parameters);
}
export async function stop() {
await sudo('tc', 'qdisc', 'del', 'dev', 'lo', 'root');
Expand Down
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