Add some additional comments to the demos

[thirdparty/openssl.git] / demos / guide / quic-multi-stream.c

/*
 *  Copyright 2023 The OpenSSL Project Authors. All Rights Reserved.
 *
 *  Licensed under the Apache License 2.0 (the "License").  You may not use
 *  this file except in compliance with the License.  You can obtain a copy
 *  in the file LICENSE in the source distribution or at
 *  https://www.openssl.org/source/license.html
 */

/*
 * NB: Changes to this file should also be reflected in
 * doc/man7/ossl-guide-quic-multi-stream.pod
 */

#include <string.h>

/* Include the appropriate header file for SOCK_DGRAM */
#ifdef _WIN32 /* Windows */
# include <winsock2.h>
#else /* Linux/Unix */
# include <sys/socket.h>
#endif

#include <openssl/bio.h>
#include <openssl/ssl.h>
#include <openssl/err.h>

/* Helper function to create a BIO connected to the server */
static BIO *create_socket_bio(const char *hostname, const char *port,
                              BIO_ADDR **peer_addr)
{
    int sock = -1;
    BIO_ADDRINFO *res;
    const BIO_ADDRINFO *ai = NULL;
    BIO *bio;

    /*
     * Lookup IP address info for the server.
     */
    if (!BIO_lookup_ex(hostname, port, BIO_LOOKUP_CLIENT, 0, SOCK_DGRAM, 0,
                       &res))
        return NULL;

    /*
     * Loop through all the possible addresses for the server and find one
     * we can connect to.
     */
    for (ai = res; ai != NULL; ai = BIO_ADDRINFO_next(ai)) {
        /*
         * Create a TCP socket. We could equally use non-OpenSSL calls such
         * as "socket" here for this and the subsequent connect and close
         * functions. But for portability reasons and also so that we get
         * errors on the OpenSSL stack in the event of a failure we use
         * OpenSSL's versions of these functions.
         */
        sock = BIO_socket(BIO_ADDRINFO_family(ai), SOCK_DGRAM, 0, 0);
        if (sock == -1)
            continue;

        /* Connect the socket to the server's address */
        if (!BIO_connect(sock, BIO_ADDRINFO_address(ai), 0)) {
            BIO_closesocket(sock);
            sock = -1;
            continue;
        }

        /* Set to nonblocking mode */
        if (!BIO_socket_nbio(sock, 1)) {
            sock = -1;
            continue;
        }

        break;
    }

    if (sock != -1) {
        *peer_addr = BIO_ADDR_dup(BIO_ADDRINFO_address(ai));
        if (*peer_addr == NULL) {
            BIO_closesocket(sock);
            return NULL;
        }
    }


    /* Free the address information resources we allocated earlier */
    BIO_ADDRINFO_free(res);

    /* If sock is -1 then we've been unable to connect to the server */
    if (sock == -1)
        return NULL;

    /* Create a BIO to wrap the socket*/
    bio = BIO_new(BIO_s_datagram());
    if (bio == NULL)
        BIO_closesocket(sock);

    /*
     * Associate the newly created BIO with the underlying socket. By
     * passing BIO_CLOSE here the socket will be automatically closed when
     * the BIO is freed. Alternatively you can use BIO_NOCLOSE, in which
     * case you must close the socket explicitly when it is no longer
     * needed.
     */
    BIO_set_fd(bio, sock, BIO_CLOSE);

    return bio;
}

/* Server hostname and port details. Must be in quotes */
#ifndef HOSTNAME
# define HOSTNAME "www.example.com"
#endif
#ifndef PORT
# define PORT     "443"
#endif

/*
 * Simple application to send basic HTTP/1.0 requests to a server and print the
 * response on the screen. Note that HTTP/1.0 over QUIC is not a real protocol
 * and will not be supported by real world servers. This is for demonstration
 * purposes only.
 */
int main(void)
{
    SSL_CTX *ctx = NULL;
    SSL *ssl = NULL;
    SSL *stream1 = NULL, *stream2 = NULL, *stream3 = NULL;
    BIO *bio = NULL;
    int res = EXIT_FAILURE;
    int ret;
    unsigned char alpn[] = { 8, 'h', 't', 't', 'p', '/', '1', '.', '0' };
    const char *request1 =
        "GET /request1.html HTTP/1.0\r\nConnection: close\r\nHost: "HOSTNAME"\r\n\r\n";
    const char *request2 =
        "GET /request2.html HTTP/1.0\r\nConnection: close\r\nHost: "HOSTNAME"\r\n\r\n";
    size_t written, readbytes;
    char buf[160];
    BIO_ADDR *peer_addr = NULL;

    /*
     * Create an SSL_CTX which we can use to create SSL objects from. We
     * want an SSL_CTX for creating clients so we use
     * OSSL_QUIC_client_method() here.
     */
    ctx = SSL_CTX_new(OSSL_QUIC_client_method());
    if (ctx == NULL) {
        printf("Failed to create the SSL_CTX\n");
        goto end;
    }

    /*
     * Configure the client to abort the handshake if certificate
     * verification fails. Virtually all clients should do this unless you
     * really know what you are doing.
     */
    SSL_CTX_set_verify(ctx, SSL_VERIFY_PEER, NULL);

    /* Use the default trusted certificate store */
    if (!SSL_CTX_set_default_verify_paths(ctx)) {
        printf("Failed to set the default trusted certificate store\n");
        goto end;
    }

    /* Create an SSL object to represent the TLS connection */
    ssl = SSL_new(ctx);
    if (ssl == NULL) {
        printf("Failed to create the SSL object\n");
        goto end;
    }

    /*
     * We will use multiple streams so we will disable the default stream mode.
     * This is not a requirement for using multiple streams but is recommended.
     */
    if (!SSL_set_default_stream_mode(ssl, SSL_DEFAULT_STREAM_MODE_NONE)) {
        printf("Failed to disable the default stream mode\n");
        goto end;
    }

    /*
     * Create the underlying transport socket/BIO and associate it with the
     * connection.
     */
    bio = create_socket_bio(HOSTNAME, PORT, &peer_addr);
    if (bio == NULL) {
        printf("Failed to crete the BIO\n");
        goto end;
    }
    SSL_set_bio(ssl, bio, bio);

    /*
     * Tell the server during the handshake which hostname we are attempting
     * to connect to in case the server supports multiple hosts.
     */
    if (!SSL_set_tlsext_host_name(ssl, HOSTNAME)) {
        printf("Failed to set the SNI hostname\n");
        goto end;
    }

    /*
     * Ensure we check during certificate verification that the server has
     * supplied a certificate for the hostname that we were expecting.
     * Virtually all clients should do this unless you really know what you
     * are doing.
     */
    if (!SSL_set1_host(ssl, HOSTNAME)) {
        printf("Failed to set the certificate verification hostname");
        goto end;
    }

    /* SSL_set_alpn_protos returns 0 for success! */
    if (SSL_set_alpn_protos(ssl, alpn, sizeof(alpn)) != 0) {
        printf("Failed to set the ALPN for the connection\n");
        goto end;
    }

    /* Set the IP address of the remote peer */
    if (!SSL_set_initial_peer_addr(ssl, peer_addr)) {
        printf("Failed to set the initial peer address\n");
        goto end;
    }

    /* Connect to the server and perform the TLS handshake */
    if ((ret = SSL_connect(ssl)) < 1) {
        /*
         * If the failure is due to a verification error we can get more
         * information about it from SSL_get_verify_result().
         */
        if (SSL_get_verify_result(ssl) != X509_V_OK)
            printf("Verify error: %s\n",
                X509_verify_cert_error_string(SSL_get_verify_result(ssl)));
        goto end;
    }

    /*
     * We create two new client initiated streams. The first will be
     * bi-directional, and the second will be uni-directional.
     */
    stream1 = SSL_new_stream(ssl, 0);
    stream2 = SSL_new_stream(ssl, SSL_STREAM_FLAG_UNI);
    if (stream1 == NULL || stream2 == NULL) {
        printf("Failed to create streams\n");
        goto end;
    }

    /* Write an HTTP GET request on each of our streams to the peer */
    if (!SSL_write_ex(stream1, request1, strlen(request1), &written)) {
        printf("Failed to write HTTP request on stream 1\n");
        goto end;
    }

    if (!SSL_write_ex(stream2, request2, strlen(request2), &written)) {
        printf("Failed to write HTTP request on stream 2\n");
        goto end;
    }

    /*
     * In this demo we read all the data from one stream before reading all the
     * data from the next stream for simplicity. In practice there is no need to
     * do this. We can interleave IO on the different streams if we wish, or
     * manage the streams entirely separately on different threads.
     */

    printf("Stream 1 data:\n");
    /*
     * Get up to sizeof(buf) bytes of the response from stream 1 (which is a
     * bidirectional stream). We keep reading until the server closes the
     * connection.
     */
    while (SSL_read_ex(stream1, buf, sizeof(buf), &readbytes)) {
        /*
        * OpenSSL does not guarantee that the returned data is a string or
        * that it is NUL terminated so we use fwrite() to write the exact
        * number of bytes that we read. The data could be non-printable or
        * have NUL characters in the middle of it. For this simple example
        * we're going to print it to stdout anyway.
        */
        fwrite(buf, 1, readbytes, stdout);
    }
    /* In case the response didn't finish with a newline we add one now */
    printf("\n");

    /*
     * Check whether we finished the while loop above normally or as the
     * result of an error. The 0 argument to SSL_get_error() is the return
     * code we received from the SSL_read_ex() call. It must be 0 in order
     * to get here. Normal completion is indicated by SSL_ERROR_ZERO_RETURN. In
     * QUIC terms this means that the peer has sent FIN on the stream to
     * indicate that no further data will be sent.
     */
    if (SSL_get_error(stream1, 0) != SSL_ERROR_ZERO_RETURN) {
        /*
         * Some error occurred other than a graceful close down by the
         * peer.
         */
        printf ("Failed reading remaining data from stream 1\n");
        goto end;
    }

    /*
     * In our hypothetical HTTP/1.0 over QUIC protocol that we are using we
     * assume that the server will respond with a server initiated stream
     * containing the data requested in our uni-directional stream. This doesn't
     * really make sense to do in a real protocol, but its just for
     * demonstration purposes.
     *
     * We're using blocking mode so this will block until a stream becomes
     * available. We could override this behaviour if we wanted to by setting
     * the SSL_ACCEPT_STREAM_NO_BLOCK flag in the second argument below.
     */
    stream3 = SSL_accept_stream(ssl, 0);
    if (stream3 == NULL) {
        printf("Failed to accept a new stream\n");
        goto end;
    }

    printf("Stream 3 data:\n");
    /*
     * Read the data from stream 3 like we did for stream 1 above. Note that
     * stream 2 was uni-directional so there is no data to be read from that
     * one.
     */
    while (SSL_read_ex(stream3, buf, sizeof(buf), &readbytes))
        fwrite(buf, 1, readbytes, stdout);
    printf("\n");

    /* Check for errors on the stream */
    if (SSL_get_error(stream3, 0) != SSL_ERROR_ZERO_RETURN) {
        printf ("Failed reading remaining data from stream 3\n");
        goto end;
    }

    /*
     * Repeatedly call SSL_shutdown() until the connection is fully
     * closed.
     */
    do {
        ret = SSL_shutdown(ssl);
        if (ret < 0) {
            printf("Error shutting down: %d\n", ret);
            goto end;
        }
    } while (ret != 1);

    /* Success! */
    res = EXIT_SUCCESS;
 end:
    /*
     * If something bad happened then we will dump the contents of the
     * OpenSSL error stack to stderr. There might be some useful diagnostic
     * information there.
     */
    if (res == EXIT_FAILURE)
        ERR_print_errors_fp(stderr);

    /*
     * Free the resources we allocated. We do not free the BIO object here
     * because ownership of it was immediately transferred to the SSL object
     * via SSL_set_bio(). The BIO will be freed when we free the SSL object.
     */
    SSL_free(ssl);
    SSL_free(stream1);
    SSL_free(stream2);
    SSL_free(stream3);
    SSL_CTX_free(ctx);
    BIO_ADDR_free(peer_addr);
    return res;
}