/**
* Auto-discovery utility for finding ExpoSnap servers on the local network
*/
interface DiscoveryResult {
ip: string;
port: number;
service: string;
version: string;
}
/**
* Gets common IP ranges to scan based on device's network
*/
function getIPRangesToScan(): string[] {
// Common private network ranges
return [
'192.168.1', // Most home routers
'192.168.0', // Alternative home router config
'10.0.0', // Corporate networks, some routers
'172.16.0', // Less common but possible
'192.168.2', // Some ISP router configs
];
}
/**
* Tests a single IP address for ExpoSnap server
*/
async function testIP(
ip: string,
port: number,
timeoutMs: number = 1000
): Promise<DiscoveryResult | null> {
const controller = new AbortController();
const timeoutId = setTimeout(() => controller.abort(), timeoutMs);
try {
const response = await fetch(`http://${ip}:${port}/ping`, {
method: 'GET',
signal: controller.signal,
headers: {
Accept: 'application/json',
},
});
if (response.ok) {
const data = await response.json();
if (data.service === 'exposnap') {
return {
ip,
port: data.port || port,
service: data.service,
version: data.version || 'unknown',
};
}
}
return null;
} catch {
return null;
} finally {
clearTimeout(timeoutId);
}
}
/**
* Scans a single IP range for ExpoSnap servers
*/
async function scanIPRange(
baseIP: string,
port: number = 3333
): Promise<DiscoveryResult | null> {
const promises: Promise<DiscoveryResult | null>[] = [];
// Scan common host IPs first (routers, common static IPs)
const priorityIPs = [100, 101, 102, 1, 2, 10, 20, 50];
for (const hostNum of priorityIPs) {
const ip = `${baseIP}.${hostNum}`;
promises.push(testIP(ip, port, 800));
}
// Check priority IPs first
const priorityResults = await Promise.all(promises);
const found = priorityResults.find(result => result !== null);
if (found) {
return found;
}
// If not found in priority IPs, scan the full range (but skip already checked)
const fullScanPromises: Promise<DiscoveryResult | null>[] = [];
for (let i = 1; i <= 254; i++) {
if (!priorityIPs.includes(i)) {
const ip = `${baseIP}.${i}`;
fullScanPromises.push(testIP(ip, port, 500));
}
}
const fullResults = await Promise.all(fullScanPromises);
return fullResults.find(result => result !== null) || null;
}
export async function discoverServer(
port: number = 3333
): Promise<DiscoveryResult | null> {
const ranges = getIPRangesToScan();
// try each ip range with the specified port
for (const range of ranges) {
try {
const result = await scanIPRange(range, port);
if (result) {
return result;
}
} catch {
// continue to next range
continue;
}
}
return null;
}
/**
* Helper to get server URL from discovery result
*/
export function getServerURL(result: DiscoveryResult): string {
return `http://${result.ip}:${result.port}`;
}
