Sending binary data between client and server - c

Question

I am implementing a simple server-client inter-process communication by sending data in binary format from the client to the server. The program is simple: it sends an unsigned number from 1 to 5, once at a time, in binary format. The server reads in the these binary data and converts it back to an unsigned int. However, when I tried to read in on the server size, my binary data was changing. How can I make the reading protocol to read in the data in a format that I sent. I appreciate all helps that I can get! Thank you.
Here is my implementation of the server:
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <unistd.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <limits.h>
#include <netdb.h>
#define BUFFER_SIZE 10
int main(int argc, char *argv[])
{
int serv_sock, ret, data_socket;
socklen_t client_sock;
struct sockaddr_in serv_addr;
struct sockaddr_in client_addr;
// char buffer[BUFFER_SIZE];
uint32_t buffer = 0;
FILE *fp;
char hostname[HOST_NAME_MAX];
char ipaddr[INET_ADDRSTRLEN];
char port[6];
serv_sock = socket(AF_INET, SOCK_STREAM, 0);
if (serv_sock == -1)
{
perror("socket");
exit(1);
}
memset(&serv_addr, 0, sizeof(serv_addr));
serv_addr.sin_family = AF_INET;
serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
serv_addr.sin_port = htons(35000);
ret = bind(serv_sock, (const struct sockaddr *)&serv_addr, sizeof(serv_addr)); // bind socket to server address
if (ret == -1)
{
printf("bind error: %s\n", strerror(errno));
exit(1);
}
listen(serv_sock, 20);
// get hostname
gethostname(hostname, HOST_NAME_MAX);
// get ip address
getnameinfo((struct sockaddr *)&serv_addr, sizeof(serv_addr), ipaddr, INET_ADDRSTRLEN, port, 6, NI_NUMERICHOST | NI_NUMERICSERV);
// get port number
printf("Server %s is running on %s : %s\n", hostname, ipaddr, port);
while (1)
{
data_socket = accept(serv_sock, (struct sockaddr *)&client_addr, &client_sock);
// print client host name and ip address
getnameinfo((struct sockaddr *)&client_addr, sizeof(client_addr), hostname, HOST_NAME_MAX, port, 6, NI_NUMERICHOST | NI_NUMERICSERV);
printf("Client %s is connected to %s : %s\n", hostname, ipaddr, port);
if (data_socket == -1)
{
printf("accept error: %s\n", strerror(errno));
exit(1);
}
while (1){
int n = read(data_socket, &buffer, sizeof(uint32_t));
if (n == -1)
{
printf("read error: %s\n", strerror(errno));
exit(1);
}
if (n == 0)
{
break;
}
uint32_t temp = ntohl(buffer);
printf("%d\n", temp);
}
close(data_socket);
// if (!strncmp(buffer, "418", sizeof(buffer)))
// {
// break;
// }
}
close(serv_sock);
return 0;
}
Client implimentation:
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <unistd.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <inttypes.h>
int main(int argc, char *argv[])
{
struct sockaddr_in addr;
int ret, data_socket, i;
unsigned int num_arr[5] = {1, 2, 3, 4, 5};
char send_str[100];
data_socket = socket(AF_INET, SOCK_STREAM, 0);
if (data_socket == -1)
{
perror("socket");
exit(1);
}
memset(&addr, 0, sizeof(addr));
addr.sin_family = AF_INET;
addr.sin_addr.s_addr = inet_addr("127.0.0.1");
addr.sin_port = htons(35000);
ret = connect(data_socket, (const struct sockaddr *)&addr, sizeof(addr));
if (ret == -1)
{
printf("connect error: %s\n", strerror(errno));
exit(1);
}
for (i = 0; i < 5; i++)
{
// sprintf(send_str, "%d\n", num_arr[i]);
// now send data as binary data
uint32_t num = htonl(num_arr[i]);
printf("%d\n", num);
printf("%d\n", ntohl(num));
write(data_socket, &num, sizeof(num));
write(data_socket, "\n", 1);
}
uint32_t delimiter = htonl(-1);
write(data_socket, &delimiter, sizeof(uint32_t));
if (argc == 2)
{
if (strncmp(argv[1], "quit", 4) == 0)
{
printf("User quits\n");
ret = write(data_socket, "418\n", 4);
}
else
{
printf("Wrong Argument\n");
}
}
close(data_socket);
return 0;
}