#include "util.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>

#ifndef IFF_MULTI_QUEUE
#define IFF_MULTI_QUEUE 0x0100
#endif

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

int tun_has_multiqueue( int tun_fd )
{
    int features;

    if ( ioctl( tun_fd, TUNGETFEATURES, &features ) < 0) {
        warn("Kernel doesn't support TUNGETFEATURES, assuming no multiqueue");
        features = 0;
    }

    return features & IFF_MULTI_QUEUE;
}

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

    if ( ( fd = open( "/dev/net/tun", O_RDWR ) ) < 0 ) {
        warn( "Error %s (%i) opening tun to create %s", strerror(errno), errno, name );
        return -1;
    }
    
    memset( &ifr, 0, sizeof( struct ifreq ) );
    
    ifr.ifr_flags = IFF_TUN | IFF_NO_PI;
    
    if ( multi ) {
        if ( !tun_has_multiqueue( fd ) ) {
            warn( "multiqueue requested but kernel doesn't support it" );
            close( fd );
            return -1;
        }

        debug( "Creating multi-queue device" );
        ifr.ifr_flags |= IFF_MULTI_QUEUE;
    }


    strncpy( ifr.ifr_name, name, IFNAMSIZ );
    
    while ( (err = ioctl( fd, TUNSETIFF, (void*) &ifr ) ) < 0 ) {
        if ( errno != EBUSY ) {
            warn( "Error creating tun device %s: %s (%i)", name, strerror(errno), 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 *ifname, int multi  )
{
    memset( session, 0, sizeof( struct session ) );

    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 );
    
    session->fd = create_tun( ifname, multi );
    if ( session->fd == -1 ) {
        warn( "Error opening %s for listening", ifname );
        rlocs_free( session->rlocs );
        return 0;
    }
    link_set_up( ifname, 1 );

    return 1;
}

int session_upgrade_rlocs( struct session *session, int argc, char** args )
{
    int i, num_rlocs = argc / 2;
    
    if ( argc%2 != 0 ) {
        warn( "Odd number of arguments. Format: [<rlc> <filename>]n" );
        return 0;
    }
    
    for ( i = 0 ; i < num_rlocs ; i++ ) {
        char *rloc_str = args[i*2];
        char *filename = args[(i*2)+1];
        struct rloc *rloc;
        
        if ( strchr( rloc_str, ':' ) == NULL ) { /* IPv4 */
            struct in_addr ip;
            if ( inet_pton( AF_INET, rloc_str, &ip ) != 1 ) {
                warn( "Couldn't parse %s as an IPv4 address", rloc_str );
                return 0;
            }
            rloc = rloc_find_by_address( session->rlocs, &ip, NULL );
        } else { /* IPv6 */
            struct in6_addr ip6;
            if ( inet_pton( AF_INET6, rloc_str, &ip6 ) != 1 ) {
                warn( "Couldn't parse %s as an IPv6 address", rloc_str );
                return 0;
            }
            rloc = rloc_find_by_address( session->rlocs, NULL, &ip6 );            
        }
        
        if (rloc == NULL ) {
            warn( "Couldn't find rloc for %s", rloc_str );
            return 0;
        }
        
        if ( !rlocs_add_private_key( session->rlocs, rloc, filename ) ) {
            warn( "Couldn't upgrade rloc %s with %s", rloc_str, filename );
            return 0;
        }

        info( "Upgraded RLOC %s with private key %s", rloc_str, filename );
    }
    
    return 1;
}


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


// TODO: we can speed this one up, if necessary, by re-using the context.
// TODO: some error-checking
int sha256sum( unsigned char *src, size_t src_len, unsigned char dst[SHA256_DIGEST_LENGTH] )
{
    unsigned int size = SHA256_DIGEST_LENGTH;
    EVP_MD_CTX *ctx = EVP_MD_CTX_create();
    EVP_DigestInit_ex( ctx, EVP_sha256(), NULL );

    
    EVP_DigestUpdate( ctx, src, src_len );
    EVP_DigestFinal_ex( ctx, &dst[0], &size );
    EVP_MD_CTX_destroy( ctx );
    

    return size == SHA256_DIGEST_LENGTH;
}