net.c

#include <stdlib.h>                    
#include <stdio.h>                     
#include <sys/types.h>                 
#include <sys/socket.h>                
#include <arpa/inet.h>                 
#include <string.h>                    
#include <errno.h>                     
#include <unistd.h>                    

#define panic(EXPR, MSG) \             
    if (EXPR) { \                      
        fprintf(stderr, "%s:%d: %s: %s\n", __FILE__, __LINE__, #EXPR, MSG); \  
\                                      
        if (errno != 0) { \            
            fprintf(stderr, "errno: %s", strerror(errno)); \                   
        } \                            
\                                      
        abort(); \                     
    }                                  

int main() {                           
    struct sockaddr_in server;         
    server.sin_family = AF_INET;       
    server.sin_addr.s_addr = INADDR_ANY;                                       
    server.sin_port = htons(8080);     

    int fd = socket(AF_INET, SOCK_STREAM, 0);                                  
    panic(fd == -1, "unable to open socket");                                  

    panic(bind(fd, (struct sockaddr *)&server, sizeof(server)), "failed to bind");                                                                            
    panic(listen(fd, 128), "failed to setup socket to listen");                
    panic(setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &(int){ 1 }, sizeof(int)) == 1, "failed to set option")                                                    

    while (1) {                        
        struct sockaddr_in client;     
        socklen_t client_len = sizeof(client);                                 
        int cfd = accept(fd, (struct sockaddr *)&client, &client_len);         

        char buffer[2000];             
        bzero(buffer, sizeof(buffer)); 

        ssize_t read_size;             

        while((read_size = recv(cfd, buffer, 2000 , 0)) > 0) {                 
            while (read_size > 0) {    
                ssize_t sent = send(cfd, buffer, read_size, 0);                
                panic(sent < 0, "could not send data");                        
                read_size -= sent;     
            }                          
        }                              

        panic(read_size < 0, "failed to read");                                
    }                                  

close_fd:                              
    close(fd);                         
}