#include <netinet/in.h>
#include <errno.h>
#include <stdlib.h>
#include <unistd.h>
#include <netdb.h>
#include <string.h>
#include <stdio.h>

typedef unsigned int uint32;

/** Call as:  $0 src-ip src-dev dest-ip */


int createUdpSocket(uint32 sip, uint32 sp, const char* bind_dev) {
   int s = socket(AF_INET, SOCK_DGRAM, 0);   
   int r; //retval
   struct sockaddr_in my_ip_addr;

   if (s < 0) {
      perror("socket");
      return s;
   }

   memset(&my_ip_addr, '\0', sizeof(my_ip_addr));
   
   my_ip_addr.sin_family = AF_INET;
   my_ip_addr.sin_addr.s_addr = htonl(sip);
   my_ip_addr.sin_port = htons(sp);
   
   r = bind(s, (struct sockaddr*)(&my_ip_addr), sizeof(my_ip_addr));
   if (r < 0) {
      perror("bind");
      return r;
   }
   
   if (bind_dev) {
      // Bind to specific device.
      if (setsockopt(s, SOL_SOCKET, SO_BINDTODEVICE,
                     bind_dev, strlen(bind_dev) + 1)) {
         perror("BINDTODEVICE");
      }
   }//if 

   return s;
}

int toIpString(const char* ip, uint32* retval) {
   struct hostent *hp;
   *retval = 0;

   if (strcmp(ip, "0.0.0.0") == 0) {
      return 0;
   }

   if (ip[0] == 0) {
      return 0;
   }

   // It seems it can't resolve IP addresses, or tries too hard to find a name,
   // or something.  Need to check for a.b.c.d
   *retval = inet_addr(ip);
   if (*retval != INADDR_NONE) {
      *retval = ntohl(*retval);
      return 0;
   }

   // Otherwise, try to resolve it below.
   hp = gethostbyname(ip);
   if (hp == NULL) {
      return -1;
   }//if
   else {
      *retval = ntohl(*((unsigned int*)(hp->h_addr_list[0])));
      if (*retval != 0) {
         return 0;
      }
      else {
         return -1;
      }
   }
   return -1;
}

/** Call as:  $0 src-ip src-dev dest-ip */
int main(int argc, char** argv) {
   uint32 sip;
   uint32 dip;
   int s;
   int i;
   int z = 0;
   char buf[16];
   struct sockaddr_in dest_addr;

   if (argc < 3) {
      printf("usage: bind_test src-ip src-dev dest-ip\n");
      exit(2);
   }
   
   toIpString(argv[1], &sip);
   toIpString(argv[3], &dip);

   s = createUdpSocket(sip, 9, argv[2]);
   if (s < 0) {
      printf("ERROR: couldn't create udp socket.\n");
      exit(1);
   }

   // set up the destination address
   memset(&dest_addr, '\0', sizeof(dest_addr));
   dest_addr.sin_family = AF_INET;
   
   dest_addr.sin_addr.s_addr = htonl(dip);
   dest_addr.sin_port = htons(9);
   
   for (i = 0; i<5; i++) {
      int r = sendto(s, "sending text, bound", strlen("sending text, bound"),
                     0, (struct sockaddr*)(&dest_addr), sizeof(dest_addr));
      if (r < 0) {
         perror("sendto");
      }
   }

   /* unbind and send 5 more, use old API for pre-patched kernels. */
   if (setsockopt(s, SOL_SOCKET, SO_BINDTODEVICE,
                  &z, sizeof(z))) {
      perror("BINDTODEVICE");
   }//if 

   for (i = 0; i<5; i++) {
      int r = sendto(s, "sending text, un-bound", strlen("sending text, un-bound"),
                     0, (struct sockaddr*)(&dest_addr), sizeof(dest_addr));
      if (r < 0) {
         perror("sendto");
      }
   }
   
   /* unbind the right way */
   memset(&buf, 0, sizeof(buf));
   if (setsockopt(s, SOL_SOCKET, SO_BINDTODEVICE,
                  buf, sizeof(buf))) {
      perror("UN-BINDTODEVICE-2");
   }//if 

   for (i = 0; i<5; i++) {
      int r = sendto(s, "sending text, un-bound-2", strlen("sending text, un-bound-2"),
                     0, (struct sockaddr*)(&dest_addr), sizeof(dest_addr));
      if (r < 0) {
         perror("sendto");
      }
   }

   /* Unbind in the post-patch way (length of zero) */
   if (setsockopt(s, SOL_SOCKET, SO_BINDTODEVICE,
                  "", 0)) {
      perror("UN-BINDTODEVICE-3");
   }//if


   close(s);
   exit(0);
}//main