COUNTERMEASURES - Hacking: The Art of Exploitation - page 325

tinywebd.c
#include <sys/stat.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <time.h>
#include <signal.h>
#include "hacking.h"
#include "hacking-network.h"
#define PORT 80 // The port users will be connecting to
#define WEBROOT "./webroot" // The webserver's root directory
#define LOGFILE "/var/log/tinywebd.log" // Log filename
int logfd, sockfd; // Global log and socket file descriptors
void handle_connection(int, struct sockaddr_in *, int);
int get_file_size(int); // Returns the file size of open file descriptor
void timestamp(int); // Writes a timestamp to the open file descriptor
// This function is called when the process is killed.
void handle_shutdown(int signal) {
timestamp(logfd);
write(logfd, "Shutting down.\n", 16);
close(logfd);
close(sockfd);
exit(0);
}
int main(void) {
int new_sockfd, yes=1;
struct sockaddr_in host_addr, client_addr; // My address information
socklen_t sin_size;
logfd = open(LOGFILE, O_WRONLY|O_CREAT|O_APPEND, S_IRUSR|S_IWUSR);
if(logfd == -1)
fatal("opening log file");
if ((sockfd = socket(PF_INET, SOCK_STREAM, 0)) == -1)
fatal("in socket");
if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(int)) == -1)
fatal("setting socket option SO_REUSEADDR");
printf("Starting tiny web daemon.\n");
if(daemon(1, 0) == -1) // Fork to a background daemon process.
fatal("forking to daemon process");
signal(SIGTERM, handle_shutdown); // Call handle_shutdown when killed.
signal(SIGINT, handle_shutdown); // Call handle_shutdown when interrupted.
timestamp(logfd);