How to send Struct ?

[sunit]

hi,
i need to send "struct" from server to client and client should receive it.
i am not able to write the code from sending and receiving the strucutre.

My main task is : i need to generate random numbers and send it through structure to client
Program of server

#include<stdio.h>
#include<stdlib.h>
#include<sys/socket.h>
#include<sys/types.h>
#include<netinet/in.h>
#include<error.h>
#include<strings.h>
#include<unistd.h>
#include<arpa/inet.h>
#include <time.h>

#define ERROR	-1
#define MAX_CLIENTS	2
#define MAX_DATA	1024


main(int argc, char **argv)
{
	struct packet
	{
		int node;
		int temp;
		int humidity;
	};
	struct packet p1; 
	
	struct sockaddr_in server;
	struct sockaddr_in client;
	int sock;
	int new;
	int sockaddr_len = sizeof(struct sockaddr_in);
	int data_len;
	char data[MAX_DATA];



	
int i;
int a,b,c;
char d[100],e[100],f[100];
time_t t;
srand((unsigned) time(&t));

	
	
	if((sock = socket(AF_INET, SOCK_STREAM, 0)) == ERROR)
	{
		perror("server socket: ");
		exit(-1);
	}
		
	server.sin_family = AF_INET;
	server.sin_port = htons(atoi(argv[1]));
	server.sin_addr.s_addr = INADDR_ANY;
	bzero(&server.sin_zero, 8);
			
	if((bind(sock, (struct sockaddr *)&server, sockaddr_len))== ERROR)
	{
		perror("bind : ");
		exit(-1);
	}
	
	if((listen(sock, MAX_CLIENTS)) == ERROR)
	{
		perror("listen");
		exit(-1);
	}
	
	while(1) // Better signal handling required
	{
		if((new = accept(sock, (struct sockaddr *)&client, &sockaddr_len))== ERROR)
		{
			perror("accept");
			exit(-1);
		}
		
		printf("New Client connected from port no %d and IP %s\n",
		 ntohs(client.sin_port), inet_ntoa(client.sin_addr));

		data_len = 1;
				
		while(data_len)
		{
			data_len = recv(new, data, MAX_DATA, 0);
			data_len= 5;
							
a=rand()%10 ;
printf("a is %d\n",a);
sprintf(d,"%d",a);
printf("\n char no. is  %s",d);


b=rand()%100;
printf("\n b is %d\n",b);
sprintf(e,"%d",b);
printf("\n char no. is  %s",e);

c=rand()%100;
printf("\n c is %d\n",c);
sprintf(f,"%d",c);
printf("\n char no. is  %s",f);
  
p1.node=a;
p1.temp=b;
p1.humidity=c;  

printf("node_id=%u ",p1.node);
printf("temp=%u ",p1.temp);
printf("himid=%u ",p1.humidity);
  
// WriteBuffer (&p1,sizeof(p1));
 //send(new,&p1,sizeof(p1),0) ;

n=recvfrom(socket_fd,buffer,sizeof(mypdu),0,
				(struct sockaddr *)&client,&sockaddr_len);

printf("\n over");





				//send(new, data,data_len, 0);
			
				//printf("\n Sent mesg: %s", data);
				
				
		
			 
		}

		printf("Client disconnected\n");
		
		close(new);
		
	}

	close(sock);

	}

Program of client

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

#define ERROR	-1
#define BUFFER	1024


main(int argc, char **argv)
{
	struct sockaddr_in remote_server;
	int sock;
	char input[BUFFER];
	char output[BUFFER];
	int len;
	
	
	if((sock = socket(AF_INET, SOCK_STREAM, 0)) == ERROR)
	{
		perror("socket");
		exit(-1);
	}
		
	remote_server.sin_family = AF_INET;
	remote_server.sin_port = htons(atoi(argv[2]));
	remote_server.sin_addr.s_addr = inet_addr(argv[1]);
	bzero(&remote_server.sin_zero, 8);
	
	if((connect(sock, (struct sockaddr *)&remote_server, sizeof(struct sockaddr_in))) == ERROR)
	{
		perror("connect");
		exit(-1);
	}
	
	while(1)
	{
		
		fgets(input, BUFFER, stdin);
		send(sock, input, strlen(input), 0);
	

		len = recv(sock, output, BUFFER, 0);
		output[len] = '\0';
		printf("%s\n", output);
	}
	
	close(sock);
	
	
}

Please help me !!

regards

sunit

[MK27]

hi,
i need to send "struct" from server to client and client should receive it.
i am not able to write the code from sending and receiving the strucutre.

To send a struct, cast it as (char*) on the send side, gather all the data into a char buffer on the other side, and cast that back into a struct.

[sunit]

hi,
can u please explain me in details as i m new to client server programming

sunit

[sean]

A struct is basically a series of bytes, just like a string. Only, it's easier to send a string through the network, isn't it? So by casting it as (char *) you can start to treat it more like a series of bytes, send it, and your server can recieve that series of byte and convert it back into your struct. It's called serialization.

If you're unfamiliar with casting, pointers or any of that stuff - you should learn that before moving on - it's rather fundamental for any programming, not just client-server stuff.