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Copy pathinterfaces.cc
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119 lines (92 loc) · 3.34 KB
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/* -*-mode:c++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
#include <sstream>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/types.h>
#include <ifaddrs.h>
#include "interfaces.hh"
#include "exception.hh"
#include "file_descriptor.hh"
#include "util.hh"
using namespace std;
Interfaces::Interfaces()
: addresses_in_use()
{
/* add the ones getifaddrs can find */
{
ifaddrs *interface_addresses;
SystemCall( "getifaddrs", getifaddrs( &interface_addresses ) );
for ( ifaddrs *ifa = interface_addresses; ifa; ifa = ifa->ifa_next ) {
if ( ifa->ifa_addr and ifa->ifa_addr->sa_family == AF_INET ) {
addresses_in_use.emplace_back( *ifa->ifa_addr );
}
}
freeifaddrs( interface_addresses );
}
/* Now also add route destinations. */
/* Unfortunately getifaddrs does not see the destination address of a
veth interface, so read this from /proc. We could also use rtnetlink. */
FileDescriptor routes( SystemCall( "open /proc/net/route",
open( "/proc/net/route", O_RDONLY ) ) );
/* read routes */
string all_routes;
while ( true ) {
string new_chunk = routes.read();
if ( new_chunk.empty() ) { break; }
all_routes += new_chunk;
}
istringstream all_routes_stream;
all_routes_stream.str( all_routes );
/* read header row */
string header_line; getline( all_routes_stream, header_line );
if ( header_line.find( "Iface" ) != 0 ) {
throw Exception( "/proc/net/route", "unknown format" );
}
for ( string line; getline( all_routes_stream, line ); ) {
/* parse the line */
auto dest_start = line.find( "\t" );
auto dest_end = line.find( "\t", dest_start + 1 );
if ( dest_start == string::npos or dest_end == string::npos ) {
61AB
throw Exception( "/proc/net/route line", "unknown format" );
}
dest_start += 1;
size_t len = dest_end - dest_start;
if ( len != 8 ) {
throw Exception( "/proc/net/route destination address", "unknown format" );
}
string dest_address = line.substr( dest_start, len );
sockaddr_in ip;
zero( ip );
ip.sin_family = AF_INET;
ip.sin_addr.s_addr = myatoi( dest_address, 16 );
addresses_in_use.emplace_back( ip );
}
}
bool Interfaces::address_in_use( const Address & addr ) const
{
for ( const auto & x : addresses_in_use ) {
if ( addr == x ) {
return true;
}
}
return false;
}
pair< Address, uint16_t > Interfaces::first_unassigned_address( uint16_t last_octet ) const
{
while ( last_octet <= 255 ) {
Address candidate = Address::cgnat( last_octet );
if ( !address_in_use( candidate ) ) {
return make_pair( candidate, last_octet );
}
last_octet++;
}
throw Exception( "Interfaces", "could not find free interface address" );
}
std::pair< Address, Address > two_unassigned_addresses( void )
{
static Interfaces interface_list_on_program_startup;
auto 1 );
auto two = interface_list_on_program_startup.first_unassigned_address( one.second + 1 );
return make_pair( one.first, two.first );
}