138 lines
3.4 KiB
C
138 lines
3.4 KiB
C
/*
|
|
** server.c -- a stream socket server demo
|
|
*/
|
|
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <unistd.h>
|
|
#include <errno.h>
|
|
#include <string.h>
|
|
#include <sys/types.h>
|
|
#include <sys/socket.h>
|
|
#include <netinet/in.h>
|
|
#include <netdb.h>
|
|
#include <arpa/inet.h>
|
|
#include <sys/wait.h>
|
|
#include <signal.h>
|
|
|
|
#define PORT "3490" // the port users will be connecting to
|
|
|
|
#define BACKLOG 10 // how many pending connections queue will hold
|
|
|
|
void sigchld_handler(int s)
|
|
{
|
|
(void)s; // quiet unused variable warning
|
|
|
|
// waitpid() might overwrite errno, so we save and restore it:
|
|
int saved_errno = errno;
|
|
|
|
while(waitpid(-1, NULL, WNOHANG) > 0);
|
|
|
|
errno = saved_errno;
|
|
}
|
|
|
|
|
|
// get sockaddr, IPv4 or IPv6:
|
|
void *get_in_addr(struct sockaddr *sa)
|
|
{
|
|
if (sa->sa_family == AF_INET) {
|
|
return &(((struct sockaddr_in*)sa)->sin_addr);
|
|
}
|
|
|
|
return &(((struct sockaddr_in6*)sa)->sin6_addr);
|
|
}
|
|
|
|
int main(void)
|
|
{
|
|
// listen on sock_fd, new connection on new_fd
|
|
int sockfd, new_fd;
|
|
struct addrinfo hints, *servinfo, *p;
|
|
struct sockaddr_storage their_addr; // connector's address info
|
|
socklen_t sin_size;
|
|
struct sigaction sa;
|
|
int yes=1;
|
|
char s[INET6_ADDRSTRLEN];
|
|
int rv;
|
|
|
|
memset(&hints, 0, sizeof hints);
|
|
hints.ai_family = AF_INET;
|
|
hints.ai_socktype = SOCK_STREAM;
|
|
hints.ai_flags = AI_PASSIVE; // use my IP
|
|
|
|
if ((rv = getaddrinfo(NULL, PORT, &hints, &servinfo)) != 0) {
|
|
fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));
|
|
return 1;
|
|
}
|
|
|
|
// loop through all the results and bind to the first we can
|
|
for(p = servinfo; p != NULL; p = p->ai_next) {
|
|
if ((sockfd = socket(p->ai_family, p->ai_socktype,
|
|
p->ai_protocol)) == -1) {
|
|
perror("server: socket");
|
|
continue;
|
|
}
|
|
|
|
if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &yes,
|
|
sizeof(int)) == -1) {
|
|
perror("setsockopt");
|
|
exit(1);
|
|
}
|
|
|
|
if (bind(sockfd, p->ai_addr, p->ai_addrlen) == -1) {
|
|
close(sockfd);
|
|
perror("server: bind");
|
|
continue;
|
|
}
|
|
|
|
break;
|
|
}
|
|
|
|
freeaddrinfo(servinfo); // all done with this structure
|
|
|
|
if (p == NULL) {
|
|
fprintf(stderr, "server: failed to bind\n");
|
|
exit(1);
|
|
}
|
|
|
|
if (listen(sockfd, BACKLOG) == -1) {
|
|
perror("listen");
|
|
exit(1);
|
|
}
|
|
|
|
sa.sa_handler = sigchld_handler; // reap all dead processes
|
|
sigemptyset(&sa.sa_mask);
|
|
sa.sa_flags = SA_RESTART;
|
|
if (sigaction(SIGCHLD, &sa, NULL) == -1) {
|
|
perror("sigaction");
|
|
exit(1);
|
|
}
|
|
|
|
printf("server: waiting for connections...\n");
|
|
|
|
while(1) { // main accept() loop
|
|
sin_size = sizeof their_addr;
|
|
new_fd = accept(sockfd, (struct sockaddr *)&their_addr,
|
|
&sin_size);
|
|
if (new_fd == -1) {
|
|
perror("accept");
|
|
continue;
|
|
}
|
|
|
|
inet_ntop(their_addr.ss_family,
|
|
get_in_addr((struct sockaddr *)&their_addr),
|
|
s, sizeof s);
|
|
printf("server: got connection from %s\n", s);
|
|
|
|
if (!fork()) { // this is the child process
|
|
close(sockfd); // child doesn't need the listener
|
|
if (send(new_fd, "Hello, world!", 13, 0) == -1)
|
|
perror("send");
|
|
close(new_fd);
|
|
exit(0);
|
|
}
|
|
close(new_fd); // parent doesn't need this
|
|
}
|
|
|
|
return 0;
|
|
}
|