121 lines
2.6 KiB
C
121 lines
2.6 KiB
C
/* blackhole.c - eats incoming messages, does nothing, just for testing
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* @BAKE cc -O2 -std=gnu89 -Wall -Wextra -Wpedantic $@ -o $*
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* Basically ripped from <https://beej.us/guide/bgnet/html//index.html#what-is-a-socket>
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <errno.h>
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#include <string.h>
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <netinet/in.h>
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#include <netdb.h>
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#include <arpa/inet.h>
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#include <sys/wait.h>
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#include <signal.h>
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#define PORT "91991"
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#define BACKLOG 1
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void sigchld_handler(int s) {
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int saved_errno = errno;
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(void)s;
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while(waitpid(-1, NULL, WNOHANG) > 0);
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errno = saved_errno;
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}
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void *get_in_addr(struct sockaddr *sa) {
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if (sa->sa_family == AF_INET) {
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return &(((struct sockaddr_in*)sa)->sin_addr);
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}
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return &(((struct sockaddr_in6*)sa)->sin6_addr);
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}
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int main (void) {
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int sockfd, connfd, rv, yes = 1;
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struct addrinfo hints, *servinfo, *p;
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struct sockaddr_storage their_addr;
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char s[INET6_ADDRSTRLEN];
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socklen_t sin_size;
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struct sigaction sa;
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memset(&hints, 0, sizeof hints);
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hints.ai_family = AF_UNSPEC;
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hints.ai_socktype = SOCK_STREAM;
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hints.ai_flags = AI_PASSIVE;
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if ((rv = getaddrinfo(NULL, PORT, &hints, &servinfo)) != 0) {
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fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));
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return 1;
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}
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for(p = servinfo; p != NULL; p = p->ai_next) {
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if ((sockfd = socket(p->ai_family, p->ai_socktype,
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p->ai_protocol)) == -1) {
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perror("server: socket");
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continue;
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}
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if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &yes,
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sizeof(int)) == -1) {
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perror("setsockopt");
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exit(1);
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}
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if (bind(sockfd, p->ai_addr, p->ai_addrlen) == -1) {
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close(sockfd);
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perror("server: bind");
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continue;
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}
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break;
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}
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freeaddrinfo(servinfo);
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if (p == NULL) {
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fprintf(stderr, "server: failed to bind\n");
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exit(1);
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}
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if (listen(sockfd, BACKLOG) == -1) {
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perror("listen");
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exit(1);
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}
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sa.sa_handler = sigchld_handler;
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sigemptyset(&sa.sa_mask);
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sa.sa_flags = SA_RESTART;
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if (sigaction(SIGCHLD, &sa, NULL) == -1) {
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perror("sigaction");
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exit(1);
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}
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printf("server: waiting for connections...\n");
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while (1) {
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sin_size = sizeof their_addr;
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connfd = accept(sockfd, (struct sockaddr *)&their_addr, &sin_size);
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if (connfd == -1) {
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perror("accept");
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continue;
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}
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inet_ntop(their_addr.ss_family, get_in_addr((struct sockaddr *)&their_addr), s, sizeof s);
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printf("server: got connection from %s\n", s);
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if (!fork()) {
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close(sockfd);
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while (1) { sleep(5); }
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close(connfd);
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exit(0);
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}
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close(connfd);
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}
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close(sockfd);
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sockfd = -1;
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return 0;
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}
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