CLIENT   ///////////////


#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <string.h>
 
int main() {
  int c,l;
  struct sockaddr_in server,server2;
uint16_t n,r,suma;
 
  c = socket(AF_INET, SOCK_DGRAM, 0);
  if (c < 0) {
    printf("Eroare la crearea socketului client\n");
    return 1;
  }
  
  memset(&server, 0, sizeof(server));
  server.sin_port = htons(1234);
  server.sin_family = AF_INET;
  server.sin_addr.s_addr = inet_addr("127.0.0.1");

scanf("%hu",&n);
n=htons(n);  
  sendto(c, &n, sizeof(n), 0, (struct sockaddr *) &server, sizeof(server));
  l = sizeof(server2);
  memset(&server2, 0, sizeof(server2));
  recvfrom(c, &r, sizeof(r), MSG_WAITALL, (struct sockaddr *) &server2, &l);
  r=ntohs(r);
printf("r=%hu\n",r);
do{
scanf("%hu",&n);
n=htons(n);  
  sendto(c, &n, sizeof(n), 0, (struct sockaddr *) &server2, sizeof(server2));
}while(n!=0);
recvfrom(c, &suma, sizeof(suma), MSG_WAITALL, (struct sockaddr *) &server2, &l);
  suma=ntohs(suma);
printf("suma=%hu\n",suma);
  close(c);
}





SERVER /////////////////////////



#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <string.h>
 
void deservire_client(int s,struct sockaddr_in client,uint16_t n)
{
uint16_t suma=n;
int s2,l;
  s2 = socket(AF_INET, SOCK_DGRAM, 0);
printf("suma=%hu\n",n);
uint16_t r;
struct sockaddr_in server2;
  
do{r=rand()%65536;
  memset(&server2, 0, sizeof(server2));
  server2.sin_port = htons(r);
  server2.sin_family = AF_INET;
  server2.sin_addr.s_addr = INADDR_ANY;
}while (bind(s2, (struct sockaddr *) &server2, sizeof(server2)) < 0);
printf("r=%hu\n",r);
r=htons(r);  
  sendto(s2, &r, sizeof(r), 0, (struct sockaddr *) &client, sizeof(client));

do{
 l = sizeof(client);
  memset(&client, 0, sizeof(client));
 recvfrom(s2, &n, sizeof(n), MSG_WAITALL, (struct sockaddr *) &client, &l);
n=ntohs(n);
suma=suma+n;
printf("suma=%hu\n",suma);
}while(n!=0);
suma=htons(suma);
 sendto(s2, &suma, sizeof(suma), 0, (struct sockaddr *) &client, sizeof(client));
close(s2);
}


int main() {
  int s;
  struct sockaddr_in server, client;
  int l;
  uint16_t n; 
  s = socket(AF_INET, SOCK_DGRAM, 0);
  if (s < 0) {
    printf("Eroare la crearea socketului server\n");
    return 1;
  }
  
  memset(&server, 0, sizeof(server));
  server.sin_port = htons(1234);
  server.sin_family = AF_INET;
  server.sin_addr.s_addr = INADDR_ANY;
  
  if (bind(s, (struct sockaddr *) &server, sizeof(server)) < 0) {
    printf("Eroare la bind\n");
    return 1;
  }
 while(1){
  l = sizeof(client);
  memset(&client, 0, sizeof(client));
  
  recvfrom(s, &n, sizeof(n), MSG_WAITALL, (struct sockaddr *) &client, &l);
n=ntohs(n);
printf("n=%hu\n",n);

if(fork()==0)
{
deservire_client(s,client,n);
}
}
 
  close(s);
}