/** @file netlink-u2k.c
 *
 * @author marco corvi <marco_corvi@geocities.com>
 * @date feb 2005
 *
 * @brief test program for user to kernel netlink communication
 */
#include <stdio.h>
#include <string.h>

#include <sys/types.h>   // socket, getpid, bind
#include <sys/socket.h>  // socket, bind
#include <unistd.h>      // getpid
#include <asm/types.h>
#include <linux/netlink.h>

// this value is not used in knetlink.c
#define KNETLINK 17

#define PAYLOAD_SIZE 1024

int main( int argc, char ** argv )
{
  int sock;
  int i, j;
  unsigned char payload[PAYLOAD_SIZE]; // payload
  unsigned char rpayload[PAYLOAD_SIZE]; // payload
  struct msghdr msg;       // message-header
  struct sockaddr_nl addr; // my netlink address
  struct sockaddr_nl peer; // peer address
  struct nlmsghdr nlh;     // netlink message header
  struct iovec iov[2];     // iovec array

  sock = socket( AF_NETLINK, SOCK_DGRAM, KNETLINK /* NETLINK_ARPD */ );
  if ( sock < 0 ) {
    perror("Socket error");
    exit(1);
  }

  memset( &addr, 0, sizeof(addr) );
  addr.nl_family = AF_NETLINK;
  addr.nl_pad = 0;
  addr.nl_pid = getpid();
  addr.nl_groups = 0;

  { //**************** sender *****************************
    printf("Sender: my pid %d\n", getpid() );
    memset( &peer, 0, sizeof(peer) );
    peer.nl_family = AF_NETLINK;
    peer.nl_pad = 0;
    peer.nl_pid = 0;      // peer is the kernel
    peer.nl_groups = 0;   // unicast
    printf("        server pid %d\n", peer.nl_pid);

    nlh.nlmsg_len   = sizeof(nlh) + PAYLOAD_SIZE;
    nlh.nlmsg_type  = 5;
    nlh.nlmsg_flags = 0;
    nlh.nlmsg_seq   = 1;
    nlh.nlmsg_pid   = getpid();
  
    iov[0].iov_base = (void *)&nlh;
    iov[0].iov_len  = sizeof(nlh);
    iov[1].iov_base = (void *)payload;
    iov[1].iov_len  = PAYLOAD_SIZE;

    for (i=0; i<PAYLOAD_SIZE; ++i) payload[i] = i % 0xff;

    msg.msg_name    = (void *)&(peer);
    msg.msg_namelen = sizeof(peer);
    msg.msg_iov     = iov;
    msg.msg_iovlen  = 2;
    msg.msg_control = NULL;
    msg.msg_controllen = 0;
    msg.msg_flags = 0; // flags are not used by sendmsg

    if ( sendmsg( sock, &msg, 0 ) < 0 ) {
      perror("Sendmsg error");
      exit(1);
    }

    // receive the kernel reply
    // memset( rpayload, 0, PAYLOAD_SIZE );
    // memset( &nlh, 0, sizeof(nlh) );

    iov[0].iov_base = (void *)&nlh;
    iov[0].iov_len  = sizeof(nlh);
    iov[1].iov_base = (void *)rpayload;
    iov[1].iov_len  = PAYLOAD_SIZE;

    memset( &msg, 0, sizeof(msg) ); 
    msg.msg_name    = (void *)&peer;
    msg.msg_namelen = sizeof(peer);
    msg.msg_iov     = iov;
    msg.msg_iovlen  = 2;
   
    if ( recvmsg( sock, &msg, 0 ) < 0 ) {
      perror("Recvmsg error");
      exit(1);
    }
    printf("recv iov %d %p\n", msg.msg_iovlen, (void *)&(msg.msg_iov) );
    printf("  peer:len %d, family %d, pid %d\n",
      msg.msg_namelen, peer.nl_family, peer.nl_pid );
    printf("  iov size [0] %d [1] %d\n", iov[0].iov_len, iov[1].iov_len);
    printf("  nl: len %d, type %d, flags %d, seq %d, pid %d\n",
      nlh.nlmsg_len, nlh.nlmsg_type, nlh.nlmsg_flags,
      nlh.nlmsg_seq, nlh.nlmsg_pid );

    for ( i=0; i<PAYLOAD_SIZE; ++i)
      if ( rpayload[i] !=  0xff - (i % 0xff) ) break;
    if (i == PAYLOAD_SIZE) {
      printf("payload is ok \n");
    } else {
      printf("payload is broken at %d \n", i );
      for ( j=0; j<i+5 && j<PAYLOAD_SIZE; ++j )
       printf("%02x ", rpayload[j] );
    }
    

  }
  close(sock);
  return 0;
}