dnswire/examples/receiver.c

#include <dnswire/reader.h>

#include <stdio.h>
#include <errno.h>
#include <arpa/inet.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <sys/un.h>

#include "print_dnstap.c"

int main(int argc, const char* argv[])
{
    if (argc < 2) {
        fprintf(stderr, "usage: receiver [ <IP> <port> | <unix socket path> ]\n");
        return 1;
    }

    /*
     * We first initialize the reader and check that it can allocate the
     * buffers it needs.
     */

    struct dnswire_reader reader;

    if (dnswire_reader_init(&reader) != dnswire_ok) {
        fprintf(stderr, "Unable to initialize dnswire reader\n");
        return 1;
    }

    /*
     * Allow bidirectional communication over the TCP or UNIX socket.
     */
    if (dnswire_reader_allow_bidirectional(&reader, true) != dnswire_ok) {
        fprintf(stderr, "Unable to set dnswire reader to bidirectional mode\n");
        return 1;
    }

    int sockfd;

    if (argc == 2) {
        /*
         * We setup a unix socket at the given path on command line.
         */

        struct sockaddr_un path;

        memset(&path, 0, sizeof(struct sockaddr_un));
        path.sun_family = AF_UNIX;
        strncpy(path.sun_path, argv[1], sizeof(path.sun_path) - 1);

        sockfd = socket(AF_UNIX, SOCK_STREAM, 0);
        if (sockfd == -1) {
            fprintf(stderr, "socket() failed: %s\n", strerror(errno));
            return 1;
        }
        printf("socket\n");

        if (bind(sockfd, (struct sockaddr*)&path, sizeof(struct sockaddr_un))) {
            fprintf(stderr, "bind() failed: %s\n", strerror(errno));
            close(sockfd);
            return 1;
        }
        printf("bind\n");
    } else {
        /*
         * We setup and listen on the IP and port given on command line.
         */

        struct sockaddr_storage addr_store;
        struct sockaddr_in*     addr = (struct sockaddr_in*)&addr_store;
        socklen_t               addrlen;

        if (strchr(argv[1], ':')) {
            addr->sin_family = AF_INET6;
            addrlen          = sizeof(struct sockaddr_in6);
        } else {
            addr->sin_family = AF_INET;
            addrlen          = sizeof(struct sockaddr_in);
        }

        if (inet_pton(addr->sin_family, argv[1], &addr->sin_addr) != 1) {
            fprintf(stderr, "inet_pton(%s) failed: %s\n", argv[1], strerror(errno));
            return 1;
        }

        addr->sin_port = ntohs(atoi(argv[2]));

        sockfd = socket(addr->sin_family, SOCK_STREAM, IPPROTO_TCP);
        if (sockfd == -1) {
            fprintf(stderr, "socket() failed: %s\n", strerror(errno));
            return 1;
        }
        printf("socket\n");

        if (bind(sockfd, (struct sockaddr*)addr, addrlen)) {
            fprintf(stderr, "bind() failed: %s\n", strerror(errno));
            close(sockfd);
            return 1;
        }
        printf("bind\n");
    }

    if (listen(sockfd, 1)) {
        fprintf(stderr, "listen() failed: %s\n", strerror(errno));
        close(sockfd);
        return 1;
    }
    printf("listen\n");

    int clifd = accept(sockfd, 0, 0);
    if (clifd < 0) {
        fprintf(stderr, "accept() failed: %s\n", strerror(errno));
        close(sockfd);
        return 1;
    }
    printf("accept\n");

    /*
     * We have accepted connection from the sender!
     *
     * We now loop until we have a DNSTAP message, the stream was stopped
     * or we got an error.
     */

    int done = 0;

    printf("receiving...\n");
    while (!done) {
        switch (dnswire_reader_read(&reader, clifd)) {
        case dnswire_have_dnstap:
            /*
             * We received a DNSTAP message, let's print it.
             */
            print_dnstap(dnswire_reader_dnstap(reader));
            break;
        case dnswire_again:
        case dnswire_need_more:
            /*
             * This indicates that we need to call the reader again as it
             * will only do one pass in a non-blocking fasion.
             */
            break;
        case dnswire_endofdata:
            /*
             * The stream was stopped from the sender side, we're done!
             */
            printf("stopped\n");
            done = 1;
            break;
        default:
            fprintf(stderr, "dnswire_reader_read() error\n");
            done = 1;
        }
    }

    dnswire_reader_destroy(reader);

    /*
     * Time to exit, let's shutdown and close the sockets.
     */

    shutdown(clifd, SHUT_RDWR);
    close(clifd);
    close(sockfd);

    return 0;
}