#include <sys/types.h>
#include <sys/socket.h>
#include <sys/sendfile.h>
#include <stdio.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <fcntl.h>

#ifndef _MAX_SIZE_
#define _MAX_SIZE_ 80
#endif /* _MAX_SIZE_ */

#ifndef _SERVER_PORT_
#define _SERVER_PORT_ 9734
#endif /* _SERVER_PORT_ */

int err_num = 0;

/* destination address */
struct sockaddr_in dest_addr;

void send_usrname_credentials(char *usrname, int sock_fd);

void send_password_credentials(char *password, int sock_fd);

/* send file to the server */
void deliver_mail(const char *filename, int sock_fd);

/* sendfile */
ssize_t do_sendfile(int sock_fd, int input_fd, off_t offset, size_t count);

int main(int argc, char **argv)
{
      if (argc != 2)
      {
         (void)fprintf(stderr, "Usage: %s <username>\n", argv[0]);

         exit(EXIT_FAILURE);
      }

   /* username */
   char *username = argv[1];

   /* password */
   char *password = NULL;

   int err_num;

   /* socket fd */
   int socket_fd;

   int length;

   int string_len;

   int result;

   /* create the socket for the client */
   socket_fd = socket(AF_INET, SOCK_STREAM, 0);

      /* checking for "socket" errors */
      if (socket_fd < 0)
      {
         err_num = errno;

         (void)fprintf(stdout, "\"socket\" error: %s\n", strerror(err_num));

         exit(EXIT_FAILURE);
      }

   /* Initialize the socket address structure */
   memset(&dest_addr, 0, sizeof(dest_addr));
   dest_addr.sin_family = AF_INET;
   dest_addr.sin_addr.s_addr = htonl(INADDR_ANY);
   dest_addr.sin_port = htons(_SERVER_PORT_);
   length = sizeof(dest_addr);

   /* connect the socket to the server's socket */
   result = connect(socket_fd, (struct sockaddr *)&dest_addr, length);

      /* checking for "connect" errors */
      if (result < 0)
      {
         err_num = errno;

         (void)fprintf(stderr, "\"connect\" error: %s\n", strerror(err_num));

         close(socket_fd);

         exit(EXIT_FAILURE);
      }

   (void)fprintf(stdout, "Connect completed\n");

   deliver_mail("mail", socket_fd);

   /* send the username to the server
   send_usrname_credentials(username, socket_fd);

   (void)fprintf(stdout, "Utente: %s\n", username);
   */

   return 0;
}

/* send the username to the server */
void send_usrname_credentials(char *usrname, int sock_fd)
{
   struct msghdr username_cred;

   struct iovec iov;

   username_cred.msg_name = &dest_addr;
   username_cred.msg_namelen = sizeof(dest_addr);
   username_cred.msg_iov = &iov;
   username_cred.msg_iovlen = 1;
   username_cred.msg_iov->iov_base = usrname;
   username_cred.msg_iov->iov_len = (strlen(usrname) + 1);
   username_cred.msg_control = 0;
   username_cred.msg_controllen = 0;
   username_cred.msg_flags = 0;

   sendmsg(sock_fd, &username_cred, 0);
}

/* send the password to the server */
void send_password_credentials(char *password, int sock_fd)
{
   struct msghdr password_cred;

   struct iovec iov;

   password_cred.msg_name = &dest_addr;
   password_cred.msg_namelen = sizeof(dest_addr);
   password_cred.msg_iov = &iov;
   password_cred.msg_iovlen = 1;
   password_cred.msg_iov->iov_base = password;
   password_cred.msg_iov->iov_len = (strlen(password) + 1);
   password_cred.msg_control = 0;
   password_cred.msg_controllen = 0;
   password_cred.msg_flags = 0;

   sendmsg(sock_fd, &password_cred, 0);
}

/* send file to the server */
void deliver_mail(const char *filename, int sock_fd)
{
   /* file descriptor for file to send */
   int file_descriptor;

   /* argument to fstat */
   struct stat stat_buf;

   /* file offset */
   off_t offset = 0;

   int ret_val;

   size_t total_bytes_sent = 0;

   /* open the file to be sent */
   file_descriptor = open(filename, O_RDONLY);

      /* checking for "open" errors */
      if (file_descriptor < 0)
      { exit(EXIT_FAILURE); }

   /* get the size of the file to be sent */
   fstat(file_descriptor, &stat_buf);

   offset = 0;

   /* sendfile */
   total_bytes_sent = do_sendfile(sock_fd, file_descriptor, offset, stat_buf.st_size);

   (void)fprintf(stdout, "Total bytes sent: %d\n", total_bytes_sent);

   close(file_descriptor);
}

/* sendfile */
ssize_t do_sendfile(int sock_fd, int input_fd, off_t offset, size_t count)
{
   ssize_t bytes_sent;

   size_t total_bytes_sent = 0;

      while (total_bytes_sent < count)
      {
            if ((bytes_sent = sendfile(sock_fd, input_fd, &offset, (count - total_bytes_sent))) <= 0)
            {
                  if (errno == EINTR || errno == EAGAIN)
                  { continue; }

               err_num = errno;

               (void)fprintf(stderr, "\"sendfile\" error:%s\n", strerror(err_num));

               return (-1);
            }

         total_bytes_sent += bytes_sent;
      }

   return (total_bytes_sent);
}