create a comunication using getaddrinfo functions and a port

i have this program :

Code:

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#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdlib.h>


int main(void)
{
  int fd, n, addrlen;
  struct sockaddr_in addr;
  struct hostent *h;
  struct in_addr *a;
  char buffer[128];


  fd=socket(AF_INET,SOCK_DGRAM,0);
  if(fd == -1) exit(1);

  if((h=gethostbyname("tejo.ist.utl.pt"))==NULL)exit(1);

  a=(struct in_addr*)h->h_addr_list[0];
  printf("(struct in_addr*)h->h_addr_list[0] = %d \n", a->s_addr);

  memset((void*)&addr,(int)'\0',sizeof(addr));
  addr.sin_family=AF_INET;
  addr.sin_addr= *a;
  addr.sin_port= htons(8001);

  n=sendto(fd,"lll!\n",7,0,(struct sockaddr*)&addr,sizeof(addr));
    if(n==-1) exit(1);

  addrlen=sizeof(addr);
  n=recvfrom(fd,buffer,128,0,(struct sockaddr*)&addr,&addrlen);
    if(n==-1)exit(1);

  write(1,"echo: ",6);
  write(1,buffer,n);

  h=gethostbyaddr(&addr.sin_addr,sizeof(addr.sin_addr),AF_INET);
  if(h==NULL)
  printf("sent by 1 [%s:%hu]\n",inet_ntoa(addr.sin_addr),ntohs(addr.sin_port));
  else printf("2 sent by 2 [%s:%hu]\n",h->h_name,ntohs(addr.sin_port));

  close(fd);
  exit(0);
}

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i want to get rid of the functions gethostbyname() and gethostbyaddr()
so i have tried the following:

Code:

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Code:

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#define _POSIX_C_SOURCE 1
#define  _XOPEN_SOURCE


#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdlib.h> 



int main() 
{
 char *hostname = "tejo.ist.utl.pt";
 struct addrinfo hints, *res;
 struct in_addr addr;
 int err;
 char *gg;

 int fd, n, addrlen;
  struct sockaddr_in addr2;
  struct hostent *h;
  struct in_addr *a;
  char buffer[128];

  fd=socket(AF_INET,SOCK_DGRAM,0);
  if(fd == -1) exit(1);



 memset(&hints, 0, sizeof(hints));
 hints.ai_socktype = SOCK_STREAM;
 hints.ai_family = AF_INET;
 hints.ai_flags=AI_CANONNAME;

 if ((err = getaddrinfo(hostname, NULL, &hints, &res)) != 0)
 {
  printf("error %d\n", err);
  return 1;
 }

 addr.s_addr = ((struct sockaddr_in *)(res->ai_addr))->sin_addr.s_addr;
 printf("official host name: %s\n",res->ai_canonname);
 printf("ip address : %s (%08lX)\n", inet_ntoa(addr), (long unsigned int)ntohl(addr.s_addr));

 freeaddrinfo(res);

 return 0;
}

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but i dont know how to get arround at first with the gethostbyname() and after that i also dont know how to get arround the gethostbyaddr().
so can smb help me? i thank you in advance for the help