hide-eid/pass-1/util.c

#include "util.h"
#include "rlocs.h"

#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

#include <errno.h>
#include <sys/socket.h>
#include <linux/if.h>
#include <linux/if_tun.h>
#include <sys/ioctl.h>

#include <arpa/inet.h>
#include <netinet/ip.h>

void* xmalloc( size_t bytes )
{
    void* result = malloc( bytes );
    
    if ( bytes > 0 && result == NULL ) {
        warn( "Couldn't allocate memory, exiting!" );
        exit(2);
        
    }
    
    memset( result, 0, bytes );
    return result;
}

int create_tun( const char* name )
{
    int fd, err;
    struct ifreq ifr;

   if ( ( fd = open( "/dev/net/tun", O_RDWR ) ) < 0 ) {
        warn( "Error %s opening tun to create %s", strerror(errno), name );
        return -1;
    }
    
    memset( &ifr, 0, sizeof( struct ifreq ) );
    
    ifr.ifr_flags = IFF_TUN | IFF_NO_PI | IFF_UP;
    strncpy( ifr.ifr_name, name, IFNAMSIZ );
    
    if ( (err = ioctl( fd, TUNSETIFF, (void*) &ifr ) ) < 0 ) {
        warn( "Error creating tun device %s: %s", name, strerror(errno) );
        close( fd );
        return -1;
    }
    
    return fd;
}

int link_set_up( char *link_name, int state )
{
    int fd = socket( PF_INET, SOCK_DGRAM, IPPROTO_IP );
    struct ifreq ifr;


    memset( &ifr, 0, sizeof( struct ifreq ) );
    strncpy( ifr.ifr_name, link_name, IFNAMSIZ );
    
    if ( ioctl( fd, SIOCGIFFLAGS, (void*)&ifr ) < 0 ) {
        warn( "Failed to read interface flags for %s: %s", link_name, strerror(errno) );
        return 0;
    }
    
    if ( state ) {
        ifr.ifr_flags |= IFF_UP;
    } else {
        ifr.ifr_flags = ( ifr.ifr_flags & ~IFF_UP );
    }
    
    if ( ioctl( fd, SIOCSIFFLAGS, (void*)&ifr ) < 0 ) {
        warn( "Failed to set link state for interface %s to %i: %s", link_name, state, strerror(errno) );
        return 0;
    }

    return 1;

}


int session_setup( struct session *session, char *config_file, char *listen_if, char *output_if  )
{
    memset( &session, 0, sizeof( struct session ) );
    session->listen_if = -1;
    session->output_if = -1;

    session->rlocs = rlocs_new( config_file );
    
    if ( session->rlocs == NULL ) {
        warn( "Failed to get config from %s", config_file );
        return 0;
    }

    rlocs_debug_output( session->rlocs );
    
    // TODO: We can scale the tun architecture by using multiqueue and having
    // a bunch of workers, rather than this noddy scheme. If we don't jump 
    // directly to something saner, anyway...

    session->listen_if = create_tun( listen_if );
    if ( session->listen_if == -1 ) {
        warn( "Error opening %s for listening", listen_if );
        rlocs_free( session->rlocs );
        return 0;
    }
    link_set_up( listen_if, 1 );
    
    
    if ( strcmp( listen_if, output_if ) == 0 ) {
        session->same_if = 1;
        session->output_if = session->listen_if;
    } else {
        session->same_if = 0;
        session->output_if = create_tun( output_if );

        if ( session->output_if == -1 ) {
            warn( "Error opening %s for outputting", output_if );
            rlocs_free( session->rlocs );
            close( session->listen_if );
            return 0;
        }
        link_set_up( output_if, 1 );
    }
    
    return 1;
}

void session_teardown( struct session *session )
{
    rlocs_free( session->rlocs );
    if ( session->listen_if >= 0 ) {
        close( session->listen_if );
    }

    if ( session->output_if >= 0 && !session->same_if ) {
        close( session->output_if );
    }
}