[RESOLVED] udp client server. Client doesn't recieve acknowledgement from server

Hello,

gcc programing on linux

I am developed a small client server application using udp sockets.

The client sends to the server and the server can receive and display the message. However,
when the server sends a message back to the server. The server sends it, but the client always,
display the message that the client itself sent.

I am running the client and server on the same computer but different ports.

I was thinking that I might have to bind the port and ip address on the client. However, when I did this
the result was the same.

Many thanks,

client

Code:

---

#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <arpa/inet.h>
 
const size_t SERVER_PORT = 5001;
int main()
{
int socket_id = socket(AF_INET, SOCK_DGRAM, 0);
 
if(socket_id == -1)
{
printf("=== Error creating socket\n");
 
return 0;
}
 
printf("=== socket_id: %d\n", socket_id);
 
struct sockaddr_in server_addr;
memset(&server_addr, 0, sizeof(struct sockaddr_in));
 
server_addr.sin_family = AF_INET;
server_addr.sin_addr.s_addr = inet_addr("10.10.10.104");
server_addr.sin_port = htons(SERVER_PORT);

static char buffer[100] = "This is a message from the client";
size_t data_sent = 0;
data_sent = sendto(socket_id, buffer, sizeof(buffer), 0,(struct sockaddr*)&server_addr, sizeof(server_addr));
 
if(data_sent == -1)
{
printf("=== Failed to send data ===\n");
return 0;
}
printf("=== data sent: %d\n", data_sent);
 
/* Wait for a response from the server */
printf("=== Waiting acknowledgment from Server ===\n");
size_t server_size = sizeof(server_addr);
int bytes_received = 0;
/* clear xml buffer */
buffer[100] = {0};
bytes_received = recvfrom(socket_id, buffer, sizeof(buffer), 0, (struct sockaddr*) &server_addr, &server_size);
 
if(bytes_received == -1)
{
printf("=== Failed to receive bytes: %d\n", bytes_received);
return 0;
}
printf("=== Received bytes: %d\n", bytes_received);
printf("=== Received message:\n%s\n", buffer);
 
/* clean up */
close(socket_id);
 
return 0;
}

---

server

Code:

---

#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <arpa/inet.h>
 
const size_t CLIENT_PORT = 4001;
const size_t SERVER_PORT = 5001;
 
int main()
{
int socket_id = socket(AF_INET, SOCK_DGRAM, 0);
 
if(socket_id == -1)
{
printf("=== Error creating sockets\n");
return 0;
}
 
struct sockaddr_in client_addr;
memset(&client_addr, 0, sizeof(struct sockaddr_in));
struct sockaddr_in server_addr;
memset(&server_addr, 0, sizeof(struct sockaddr_in));
 
client_addr.sin_family = AF_INET;
client_addr.sin_addr.s_addr = inet_addr("127.0.0.1");
client_addr.sin_port = htons(CLIENT_PORT);
 
server_addr.sin_family = AF_INET;
server_addr.sin_addr.s_addr = htonl(INADDR_ANY);
server_addr.sin_port = htons(SERVER_PORT);
 
int bind_id = 0;
bind_id = bind(socket_id, (struct sockaddr*) &server_addr, sizeof(server_addr));
 
if(bind_id == -1)
{
printf("=== Failed to bind ===\n");
 
return 0;
}
int bytes_received = 0;
char buffer[1024];
size_t client_addr_size = sizeof(client_addr);
do
{
printf("=== Server running waiting for data ===\n");
 
/* Clean buffer */
memset(xml_buffer, 0, sizeof(buffer));
 
bytes_received = recvfrom(socket_id, buffer, sizeof(buffer), 0,
(struct sockaddr*) &client_addr, &client_addr_size);
 
if(bytes_received == -1)
{
printf("=== Failed to receive bytes from client ===\n");
 
return 0;
}
printf("=== Number of bytes received: %d\n", bytes_received);
printf("=== Received message:\n%s\n", buffer);
 
/* Send acknowledgment message back to client after a successfull receive */
size_t data_sent = 0;
char send_buffer[100] = "acknowledgement from the server."
data_sent = sendto(socket_id, send_buffer, sizeof(send_buffer), 0, (struct sockaddr*) &client_addr, sizeof(client_addr));
if(data_sent == -1)
{
printf("=== Failed to send data ===\n");
return 0;
}
 
printf("=== Data sent: %d\n", data_sent);
}
while(1);
 
/* clean up */
close(socket_id);
 
printf("=== End of Program ===\n");
 
return 0;
}

---