450 lines
11 KiB
C
450 lines
11 KiB
C
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#include <sys/poll.h>
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#include <openssl/ssl.h>
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/*
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* Demo 2: Client — Managed Connection — Nonblocking
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* ==============================================================
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*
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* This is an example of (part of) an application which uses libssl in an
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* asynchronous, nonblocking fashion. The functions show all interactions with
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* libssl the application makes, and would hypothetically be linked into a
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* larger application.
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*
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* In this example, libssl still makes syscalls directly using an fd, which is
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* configured in nonblocking mode. As such, the application can still be
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* abstracted from the details of what that fd is (is it a TCP socket? is it a
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* UDP socket?); this code passes the application an fd and the application
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* simply calls back into this code when poll()/etc. indicates it is ready.
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*/
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typedef struct app_conn_st {
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SSL *ssl;
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BIO *ssl_bio;
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int rx_need_tx, tx_need_rx;
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} APP_CONN;
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/*
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* The application is initializing and wants an SSL_CTX which it will use for
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* some number of outgoing connections, which it creates in subsequent calls to
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* new_conn. The application may also call this function multiple times to
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* create multiple SSL_CTX.
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*/
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SSL_CTX *create_ssl_ctx(void)
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{
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SSL_CTX *ctx;
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#ifdef USE_QUIC
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ctx = SSL_CTX_new(OSSL_QUIC_client_method());
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#else
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ctx = SSL_CTX_new(TLS_client_method());
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#endif
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if (ctx == NULL)
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return NULL;
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/* Enable trust chain verification. */
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SSL_CTX_set_verify(ctx, SSL_VERIFY_PEER, NULL);
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/* Load default root CA store. */
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if (SSL_CTX_set_default_verify_paths(ctx) == 0) {
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SSL_CTX_free(ctx);
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return NULL;
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}
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return ctx;
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}
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/*
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* The application wants to create a new outgoing connection using a given
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* SSL_CTX.
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*
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* hostname is a string like "openssl.org:443" or "[::1]:443".
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*/
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APP_CONN *new_conn(SSL_CTX *ctx, const char *hostname)
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{
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APP_CONN *conn;
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BIO *out, *buf;
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SSL *ssl = NULL;
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const char *bare_hostname;
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#ifdef USE_QUIC
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static const unsigned char alpn[] = {5, 'd', 'u', 'm', 'm', 'y'};
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#endif
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conn = calloc(1, sizeof(APP_CONN));
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if (conn == NULL)
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return NULL;
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out = BIO_new_ssl_connect(ctx);
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if (out == NULL) {
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free(conn);
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return NULL;
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}
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if (BIO_get_ssl(out, &ssl) == 0) {
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BIO_free_all(out);
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free(conn);
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return NULL;
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}
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/*
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* NOTE: QUIC cannot operate with a buffering BIO between the QUIC SSL
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* object in the network. In this case, the call to BIO_push() is not
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* supported by the QUIC SSL object and will be ignored, thus this code
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* works without removing this line. However, the buffering BIO is not
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* actually used as a result and should be removed when adapting code to use
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* QUIC.
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*
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* Setting a buffer as the underlying BIO on the QUIC SSL object using
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* SSL_set_bio() will not work, though BIO_s_dgram_pair is available for
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* buffering the input and output to the QUIC SSL object on the network side
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* if desired.
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*/
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buf = BIO_new(BIO_f_buffer());
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if (buf == NULL) {
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BIO_free_all(out);
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free(conn);
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return NULL;
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}
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BIO_push(out, buf);
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if (BIO_set_conn_hostname(out, hostname) == 0) {
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BIO_free_all(out);
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free(conn);
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return NULL;
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}
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/* Returns the parsed hostname extracted from the hostname:port string. */
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bare_hostname = BIO_get_conn_hostname(out);
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if (bare_hostname == NULL) {
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BIO_free_all(out);
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free(conn);
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return NULL;
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}
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/* Tell the SSL object the hostname to check certificates against. */
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if (SSL_set1_host(ssl, bare_hostname) <= 0) {
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BIO_free_all(out);
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free(conn);
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return NULL;
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}
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#ifdef USE_QUIC
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/* Configure ALPN, which is required for QUIC. */
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if (SSL_set_alpn_protos(ssl, alpn, sizeof(alpn))) {
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/* Note: SSL_set_alpn_protos returns 1 for failure. */
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BIO_free_all(out);
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return NULL;
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}
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#endif
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/* Make the BIO nonblocking. */
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BIO_set_nbio(out, 1);
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conn->ssl_bio = out;
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return conn;
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}
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/*
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* Non-blocking transmission.
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*
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* Returns -1 on error. Returns -2 if the function would block (corresponds to
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* EWOULDBLOCK).
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*/
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int tx(APP_CONN *conn, const void *buf, int buf_len)
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{
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int l;
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conn->tx_need_rx = 0;
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l = BIO_write(conn->ssl_bio, buf, buf_len);
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if (l <= 0) {
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if (BIO_should_retry(conn->ssl_bio)) {
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conn->tx_need_rx = BIO_should_read(conn->ssl_bio);
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return -2;
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} else {
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return -1;
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}
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}
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return l;
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}
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/*
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* Non-blocking reception.
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*
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* Returns -1 on error. Returns -2 if the function would block (corresponds to
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* EWOULDBLOCK).
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*/
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int rx(APP_CONN *conn, void *buf, int buf_len)
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{
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int l;
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conn->rx_need_tx = 0;
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l = BIO_read(conn->ssl_bio, buf, buf_len);
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if (l <= 0) {
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if (BIO_should_retry(conn->ssl_bio)) {
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conn->rx_need_tx = BIO_should_write(conn->ssl_bio);
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return -2;
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} else {
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return -1;
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}
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}
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return l;
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}
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/*
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* The application wants to know a fd it can poll on to determine when the
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* SSL state machine needs to be pumped.
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*/
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int get_conn_fd(APP_CONN *conn)
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{
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#ifdef USE_QUIC
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BIO_POLL_DESCRIPTOR d;
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if (!BIO_get_rpoll_descriptor(conn->ssl_bio, &d))
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return -1;
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return d.value.fd;
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#else
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return BIO_get_fd(conn->ssl_bio, NULL);
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#endif
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}
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/*
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* These functions returns zero or more of:
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*
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* POLLIN: The SSL state machine is interested in socket readability events.
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*
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* POLLOUT: The SSL state machine is interested in socket writeability events.
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*
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* POLLERR: The SSL state machine is interested in socket error events.
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*
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* get_conn_pending_tx returns events which may cause SSL_write to make
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* progress and get_conn_pending_rx returns events which may cause SSL_read
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* to make progress.
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*/
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int get_conn_pending_tx(APP_CONN *conn)
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{
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#ifdef USE_QUIC
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return (SSL_net_read_desired(conn->ssl) ? POLLIN : 0)
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| (SSL_net_write_desired(conn->ssl) ? POLLOUT : 0)
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| POLLERR;
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#else
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return (conn->tx_need_rx ? POLLIN : 0) | POLLOUT | POLLERR;
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#endif
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}
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int get_conn_pending_rx(APP_CONN *conn)
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{
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#ifdef USE_QUIC
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return get_conn_pending_tx(conn);
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#else
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return (conn->rx_need_tx ? POLLOUT : 0) | POLLIN | POLLERR;
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#endif
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}
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#ifdef USE_QUIC
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/*
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* Returns the number of milliseconds after which some call to libssl must be
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* made. Any call (BIO_read/BIO_write/BIO_pump) will do. Returns -1 if
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* there is no need for such a call. This may change after the next call
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* to libssl.
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*/
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static inline int timeval_to_ms(const struct timeval *t);
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int get_conn_pump_timeout(APP_CONN *conn)
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{
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struct timeval tv;
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int is_infinite;
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if (!SSL_get_event_timeout(conn->ssl, &tv, &is_infinite))
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return -1;
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return is_infinite ? -1 : timeval_to_ms(&tv);
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}
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/*
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* Called to advance internals of libssl state machines without having to
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* perform an application-level read/write.
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*/
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void pump(APP_CONN *conn)
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{
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SSL_handle_events(conn->ssl);
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}
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#endif
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/*
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* The application wants to close the connection and free bookkeeping
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* structures.
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*/
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void teardown(APP_CONN *conn)
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{
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BIO_free_all(conn->ssl_bio);
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free(conn);
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}
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/*
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* The application is shutting down and wants to free a previously
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* created SSL_CTX.
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*/
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void teardown_ctx(SSL_CTX *ctx)
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{
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SSL_CTX_free(ctx);
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}
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/*
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* ============================================================================
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* Example driver for the above code. This is just to demonstrate that the code
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* works and is not intended to be representative of a real application.
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*/
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#include <sys/time.h>
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static inline void ms_to_timeval(struct timeval *t, int ms)
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{
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t->tv_sec = ms < 0 ? -1 : ms/1000;
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t->tv_usec = ms < 0 ? 0 : (ms%1000)*1000;
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}
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static inline int timeval_to_ms(const struct timeval *t)
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{
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return t->tv_sec*1000 + t->tv_usec/1000;
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}
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int main(int argc, char **argv)
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{
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static char tx_msg[384], host_port[300];
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const char *tx_p = tx_msg;
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char rx_buf[2048];
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int res = 1, l, tx_len;
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#ifdef USE_QUIC
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struct timeval timeout;
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#else
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int timeout = 2000 /* ms */;
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#endif
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APP_CONN *conn = NULL;
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SSL_CTX *ctx = NULL;
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#ifdef USE_QUIC
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ms_to_timeval(&timeout, 2000);
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#endif
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if (argc < 3) {
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fprintf(stderr, "usage: %s host port\n", argv[0]);
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goto fail;
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}
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snprintf(host_port, sizeof(host_port), "%s:%s", argv[1], argv[2]);
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tx_len = snprintf(tx_msg, sizeof(tx_msg),
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"GET / HTTP/1.0\r\nHost: %s\r\n\r\n", argv[1]);
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ctx = create_ssl_ctx();
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if (ctx == NULL) {
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fprintf(stderr, "cannot create SSL context\n");
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goto fail;
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}
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conn = new_conn(ctx, host_port);
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if (conn == NULL) {
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fprintf(stderr, "cannot establish connection\n");
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goto fail;
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}
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/* TX */
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while (tx_len != 0) {
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l = tx(conn, tx_p, tx_len);
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if (l > 0) {
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tx_p += l;
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tx_len -= l;
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} else if (l == -1) {
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fprintf(stderr, "tx error\n");
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} else if (l == -2) {
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#ifdef USE_QUIC
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struct timeval start, now, deadline, t;
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#endif
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struct pollfd pfd = {0};
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#ifdef USE_QUIC
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ms_to_timeval(&t, get_conn_pump_timeout(conn));
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if (t.tv_sec < 0 || timercmp(&t, &timeout, >))
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t = timeout;
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gettimeofday(&start, NULL);
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timeradd(&start, &timeout, &deadline);
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#endif
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pfd.fd = get_conn_fd(conn);
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pfd.events = get_conn_pending_tx(conn);
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#ifdef USE_QUIC
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if (poll(&pfd, 1, timeval_to_ms(&t)) == 0)
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#else
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if (poll(&pfd, 1, timeout) == 0)
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#endif
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{
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#ifdef USE_QUIC
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pump(conn);
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gettimeofday(&now, NULL);
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if (timercmp(&now, &deadline, >=))
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#endif
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{
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fprintf(stderr, "tx timeout\n");
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goto fail;
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|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
/* RX */
|
||
|
|
for (;;) {
|
||
|
|
l = rx(conn, rx_buf, sizeof(rx_buf));
|
||
|
|
if (l > 0) {
|
||
|
|
fwrite(rx_buf, 1, l, stdout);
|
||
|
|
} else if (l == -1) {
|
||
|
|
break;
|
||
|
|
} else if (l == -2) {
|
||
|
|
#ifdef USE_QUIC
|
||
|
|
struct timeval start, now, deadline, t;
|
||
|
|
#endif
|
||
|
|
struct pollfd pfd = {0};
|
||
|
|
|
||
|
|
#ifdef USE_QUIC
|
||
|
|
ms_to_timeval(&t, get_conn_pump_timeout(conn));
|
||
|
|
if (t.tv_sec < 0 || timercmp(&t, &timeout, >))
|
||
|
|
t = timeout;
|
||
|
|
|
||
|
|
gettimeofday(&start, NULL);
|
||
|
|
timeradd(&start, &timeout, &deadline);
|
||
|
|
#endif
|
||
|
|
|
||
|
|
pfd.fd = get_conn_fd(conn);
|
||
|
|
pfd.events = get_conn_pending_rx(conn);
|
||
|
|
#ifdef USE_QUIC
|
||
|
|
if (poll(&pfd, 1, timeval_to_ms(&t)) == 0)
|
||
|
|
#else
|
||
|
|
if (poll(&pfd, 1, timeout) == 0)
|
||
|
|
#endif
|
||
|
|
{
|
||
|
|
#ifdef USE_QUIC
|
||
|
|
pump(conn);
|
||
|
|
|
||
|
|
gettimeofday(&now, NULL);
|
||
|
|
if (timercmp(&now, &deadline, >=))
|
||
|
|
#endif
|
||
|
|
{
|
||
|
|
fprintf(stderr, "rx timeout\n");
|
||
|
|
goto fail;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
res = 0;
|
||
|
|
fail:
|
||
|
|
if (conn != NULL)
|
||
|
|
teardown(conn);
|
||
|
|
if (ctx != NULL)
|
||
|
|
teardown_ctx(ctx);
|
||
|
|
return res;
|
||
|
|
}
|