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Copy pathdns_server.cc
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53 lines (42 loc) · 1.56 KB
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/* -*-mode:c++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
#include <random>
#include <thread>
#include <chrono>
#include <string>
#include "child_process.hh"
#include "system_runner.hh"
#include "util.hh"
#include "exception.hh"
#include "socket.hh"
#include "config.h"
using namespace std;
ChildProcess start_dnsmasq( const vector< string > & extra_arguments )
{
vector< string > args = { DNSMASQ, "--keep-in-foreground", "--no-resolv",
"--no-hosts", "-i", "lo", "--bind-interfaces",
"-C", "/dev/null" };
args.insert( args.end(), extra_arguments.begin(), extra_arguments.end() );
ChildProcess dnsmasq( "dnsmasq", [&] () { return ezexec( args ); }, false, SIGTERM );
/* busy-wait for dnsmasq to start answering DNS queries */
Socket server( UDP );
server.connect( Address( "0", "domain" ) );
unsigned int attempts = 0;
while ( true ) {
if ( ++attempts >= 20 ) {
throw Exception( "dnsmasq", "did not start after " + to_string( attempts ) + " attempts" );
}
try {
/* write will throw an exception if the prior UDP datagram got a bad ICMP reply */
server.write( "x" );
this_thread::sleep_for( chrono::milliseconds( 10 ) );
server.write( "x" );
break;
} catch ( const Exception & e ) {
if ( e.attempt() != "write" ) {
throw;
}
this_thread::sleep_for( chrono::milliseconds( 10 ) );
}
}
return dnsmasq;
}