#include <sys/types.h>
#include <stdio.h>
#include <sys/sysctl.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include "memory.h"

struct sockaddr_in serveraddr;
socklen_t serveraddrlen;
int serverport;
struct sockaddr_in dupaddr;
socklen_t dupaddrlen;
struct sockaddr_in dup2addr;
socklen_t dup2addrlen;
struct sockaddr_in autoaddr;
socklen_t autoaddrlen;
int serversock;
int dupsock;
int dup2sock;
int autosock;

void
bindserver(void)
{
  int bindres;
  int gsnres;
  char *serveraddrstr;

  memset(&serveraddr, '\0', sizeof(serveraddr));
#ifdef __FreeBSD__
  serveraddr.sin_len = sizeof(serveraddr);
#endif
  serveraddr.sin_family = AF_INET;
  serveraddr.sin_port = 0;
  serveraddr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
  serveraddrlen = sizeof(serveraddr);
  serversock = socket(PF_INET, SOCK_STREAM, 0);
  if (serversock < 0) {
    perror("server socket");
    exit(1);
  }
  bindres = bind(serversock, (struct sockaddr *) &serveraddr, serveraddrlen);
  if (bindres != 0) {
    perror("server bind");
    exit(1);
  }
  memset(&serveraddr, '\0', sizeof(serveraddr));
  serveraddrlen = sizeof(serveraddr);
  gsnres = getsockname(serversock, (struct sockaddr *) &serveraddr, &serveraddrlen);
  if (gsnres != 0) {
    perror("server getsockname");
    exit(1);
  }
  serverport = ntohs(serveraddr.sin_port);
  serveraddrstr = inet_ntoa(serveraddr.sin_addr);
  printf("serversock addr is %s:%d\n",
	 serveraddrstr,
	 serverport);
  
}

void
binddup(void)
{
  int bindres;
  int gsnres;
  int ssores;
  int dupport;
  int on;
  socklen_t onlen;
  char *dupaddrstr;
  int listenres;

  memcpy(&dupaddr, &serveraddr, sizeof(dupaddr));
  dupaddrlen = sizeof(dupaddr);
  dupsock = socket(PF_INET, SOCK_STREAM, 0);
  if (dupsock < 0) {
    perror("dup socket");
    exit(1);
  }
  on = 1;
  onlen = sizeof(on);
  ssores = setsockopt(dupsock, SOL_SOCKET, SO_REUSEADDR, &on, onlen);
  if (ssores != 0) {
    perror("dup setsockopt");
    exit(1);
  }   
  bindres = bind(dupsock, (struct sockaddr *) &dupaddr, dupaddrlen);
  if (bindres != 0) {
    perror("dup bind");
    printf("This error was expected, tried to bind to used addr/port\n");
    close(dupsock);
    dupsock = -1;
    return;
  }
  printf("BUG: binding duplicate socket to server addr/port succeeded\n");
  memset(&dupaddr, '\0', sizeof(dupaddr));
  dupaddrlen = sizeof(dupaddr);
  gsnres = getsockname(dupsock, (struct sockaddr *) &dupaddr, &dupaddrlen);
  if (gsnres != 0) {
    perror("dup getsockname");
    exit(1);
  }
  dupport = ntohs(dupaddr.sin_port);
  if (dupport == serverport) {
    dupaddrstr = inet_ntoa(dupaddr.sin_addr);
    printf("dupsock addr is %s:%d\n",
	   dupaddrstr,
	   dupport);
    printf("bug triggered, "
	   "address/port number conflict on sockets without SO_REUSEPORT\n");
    listenres = listen(dupsock, 10);
    if (listenres == 0)
      printf("listen() succeeded after "
	     "explicitly overlapping addr/port bind\n");
    else
      perror("listen dupsock");
    exit(1);
  }
  close(dupsock);
  dupsock = -1;
}


void
binddup2(void)
{
  int bindres;
  int gsnres;
  int ssores;
  int dup2port;
  int on;
  socklen_t onlen;
  char *dup2addrstr;
  int listenres;

  memset(&dup2addr, '\0', sizeof(dup2addr));
#ifdef __FreeBSD__
  dup2addr.sin_len = sizeof(dup2addr);
#endif
  dup2addr.sin_family = AF_INET;
  dup2addr.sin_port = htons(serverport);
  dup2addr.sin_addr.s_addr = htonl(INADDR_ANY);
  dup2addrlen = sizeof(dup2addr);
  dup2sock = socket(PF_INET, SOCK_STREAM, 0);
  if (dup2sock < 0) {
    perror("dup2 socket");
    exit(1);
  }
  on = 1;
  onlen = sizeof(on);
  ssores = setsockopt(dup2sock, SOL_SOCKET, SO_REUSEADDR, &on, onlen);
  if (ssores != 0) {
    perror("dup2 setsockopt");
    exit(1);
  }   
  bindres = bind(dup2sock, (struct sockaddr *) &dup2addr, dup2addrlen);
  if (bindres != 0) {
    perror("dup2 bind");
    printf("This error was expected, "
	   "tried to bind to used port without SO_REUSEPORT\n");
    close(dup2sock);
    dup2sock = -1;
    return;
  }
  printf("BUG: binding duplicate socket to server port succeeded\n");
  memset(&dup2addr, '\0', sizeof(dup2addr));
  dup2addrlen = sizeof(dup2addr);
  gsnres = getsockname(dup2sock, (struct sockaddr *) &dup2addr, &dup2addrlen);
  if (gsnres != 0) {
    perror("dup2 getsockname");
    exit(1);
  }
  dup2port = ntohs(dup2addr.sin_port);
  if (dup2port == serverport) {
    dup2addrstr = inet_ntoa(dup2addr.sin_addr);
    printf("dup2sock addr is %s:%d\n",
	   dup2addrstr,
	   dup2port);
    printf("overlapping explicit bind to same port number "
	   "succeeded without SO_REUSEPORT\n");
    listenres = listen(dup2sock, 10);
    if (listenres == 0)
      printf("listen succeeded after explicitly overlapping port bind\n");
    else
      perror("listen dup2sock");
  }
  close(dup2sock);
  dup2sock = -1;
}


void
bindloop(int iters)
{
  int bindres;
  int gsnres;
  int ssores;
  int autoport;
  int on;
  socklen_t onlen;
  char *autoaddrstr;
  int listenres;

  for (;;) {
    if (iters == 0)
      break;
    iters--;
    memset(&autoaddr, '\0', sizeof(autoaddr));
#ifdef __FreeBSD__
    autoaddr.sin_len = sizeof(autoaddr);
#endif
    autoaddr.sin_family = AF_INET;
    autoaddr.sin_port = 0;
    autoaddr.sin_addr.s_addr = htonl(INADDR_ANY);
    autoaddrlen = sizeof(autoaddr);
    autosock = socket(PF_INET, SOCK_STREAM, 0);
    if (autosock < 0) {
      perror("auto socket");
      exit(1);
    }
    on = 1;
    onlen = sizeof(on);
    ssores = setsockopt(autosock, SOL_SOCKET, SO_REUSEADDR, &on, onlen);
    if (ssores != 0) {
      perror("auto setsockopt");
      exit(1);
    }   
    bindres = bind(autosock, (struct sockaddr *) &autoaddr, autoaddrlen);
    if (bindres != 0) {
      perror("auto bind");
      exit(1);
    }
    memset(&autoaddr, '\0', sizeof(autoaddr));
    autoaddrlen = sizeof(autoaddr);
    gsnres = getsockname(autosock, (struct sockaddr *) &autoaddr, &autoaddrlen);
    if (gsnres != 0) {
      perror("auto getsockname");
      exit(1);
    }
    autoport = ntohs(autoaddr.sin_port);
    if (autoport == serverport) {
      autoaddrstr = inet_ntoa(autoaddr.sin_addr);
      printf("autosock addr is %s:%d\n",
	     autoaddrstr,
	     autoport);
      printf("bug triggered, "
	     "port number conflict on sockets without SO_REUSEPORT\n");
      listenres = listen(autosock, 10);
      if (listenres == 0)
	printf("listen succeded after implicitly overlapping port bind\n");
      else
	perror("listen autosock");
      exit(1);
    }
    close(autosock);
    autosock = -1;
  }
}


int
main(int argc, char **argv)
{
  int iters = 16 * 1024 * 1024; 
  bindserver();
  listen(serversock, 10);
  binddup();
  binddup2();
  bindloop(iters);
  printf("bug not triggered after %d iterations\n", iters);
  return 0;
}