124 lines
2.5 KiB
C
124 lines
2.5 KiB
C
#include <stdio.h>
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#include <string.h>
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#include <stdlib.h>
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <netdb.h>
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#include <arpa/inet.h>
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#include <netinet/in.h>
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#include <unistd.h>
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int cleanup(int sockfd)
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{
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if (close(sockfd) != 0) {
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perror("listen");
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return -1;
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}
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return 0;
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}
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int prepaddr(char *host, char *port, struct addrinfo **ainfo)
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{
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struct addrinfo hints; // hints to what we want
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memset(&hints, 0, sizeof hints);
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hints.ai_family = AF_UNSPEC; // AF_INET or AF_INET6 to force version
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hints.ai_socktype = SOCK_STREAM;
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hints.ai_flags = AI_PASSIVE;
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int status;
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if ((status = getaddrinfo(host, port, &hints, ainfo)) != 0) {
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fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(status));
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return -1;
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}
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return 0;
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}
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void printaddr(struct addrinfo *ainfo)
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{
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char ipstr[INET6_ADDRSTRLEN]; // will hold the IP adress, humanreadable
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void *addr;
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char *ipver;
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if (ainfo->ai_family == AF_INET) { // IPv4
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struct sockaddr_in *ipv4 = (struct sockaddr_in *) ainfo->ai_addr;
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addr = &(ipv4->sin_addr);
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ipver = "IPv4";
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} else { // IPv6
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struct sockaddr_in6 *ipv6 = (struct sockaddr_in6 *) ainfo->ai_addr;
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addr = &(ipv6->sin6_addr);
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ipver = "IPv6";
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}
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inet_ntop(ainfo->ai_family, addr, ipstr, sizeof ipstr);
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printf("Listening on %s: %s\n", ipver, ipstr);
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}
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int prepsocket(struct addrinfo *ainfo)
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{
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int sockfd = socket(ainfo->ai_family, ainfo->ai_socktype, ainfo->ai_protocol);
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if (sockfd == -1) {
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perror("socket");
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return -1;
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}
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if (bind(sockfd, ainfo->ai_addr, ainfo->ai_addrlen) != 0) {
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perror("bind");
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cleanup(sockfd);
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return -1;
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}
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int yes = 1;
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if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof yes) == -1) {
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perror("setsockopt");
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cleanup(sockfd);
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return -1;
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}
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if (listen(sockfd, 5) != 0) {
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perror("listen");
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cleanup(sockfd);
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return -1;
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}
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return sockfd;
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}
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int main(int argc, char *argv[])
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{
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if (argc != 3) {
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fprintf(stderr,"usage: netcalc hostname port\n");
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return 1;
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}
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struct addrinfo *ainfo;
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if (prepaddr(argv[1], argv[2], &ainfo) != 0) {
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fprintf(stderr, "server: failed to obtain adress.");
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return 1;
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}
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printaddr(ainfo);
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int sockfd;
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if ((sockfd = prepsocket(ainfo)) == -1) {
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return 1;
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}
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while (1) {
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struct sockaddr_storage c_addr;
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socklen_t sin_size = sizeof c_addr;
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int c_fd = accept(sockfd, (struct sockaddr *)&c_addr, &sin_size);
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if (c_fd == -1) {
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perror("accept");
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continue; // we do not care
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}
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if (send(c_fd, "Hello world!\n", 14, 0) == -1) {
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perror("send");
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}
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close(c_fd);
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}
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cleanup(sockfd);
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freeaddrinfo(ainfo); // free the linked list
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return 0;
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}
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