QUIC: Add HTTP/3 demo using nghttp3

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Tim Hudson <tjh@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/22369)

4 files changed, 855 insertions, 0 deletions

diff --git a/demos/http3/Makefile b/demos/http3/Makefile
new file mode 100644
index 0000000000..89bac3743e
--- /dev/null
+++ b/demos/http3/Makefile
@@ -0,0 +1,14 @@
+CFLAGS = -I../../include -g -Wall
+LDFLAGS = -L../..
+LDLIBS = -lcrypto -lssl -lnghttp3
+
+all: ossl-nghttp3-demo
+
+clean:
+	$(RM) -f ossl-nghttp3-demo *.o
+
+ossl-nghttp3-demo: ossl-nghttp3-demo.o ossl-nghttp3.o
+	$(CC) $(CFLAGS) -o "$@" $^ $(LDFLAGS) $(LDLIBS)
+
+%.o: %.c
+	$(CC) $(CFLAGS) -c -o "$@" "$<"
diff --git a/demos/http3/ossl-nghttp3-demo.c b/demos/http3/ossl-nghttp3-demo.c
new file mode 100644
index 0000000000..53acf31e40
--- /dev/null
+++ b/demos/http3/ossl-nghttp3-demo.c
@@ -0,0 +1,142 @@
+#include "ossl-nghttp3.h"
+#include <openssl/err.h>
+
+static int done;
+
+static void make_nv(nghttp3_nv *nv, const char *name, const char *value)
+{
+    nv->name        = (uint8_t *)name;
+    nv->value       = (uint8_t *)value;
+    nv->namelen     = strlen(name);
+    nv->valuelen    = strlen(value);
+    nv->flags       = NGHTTP3_NV_FLAG_NONE;
+}
+
+static int on_recv_header(nghttp3_conn *h3conn, int64_t stream_id,
+                          int32_t token,
+                          nghttp3_rcbuf *name, nghttp3_rcbuf *value,
+                          uint8_t flags,
+                          void *conn_user_data,
+                          void *stream_user_data)
+{
+    nghttp3_vec vname, vvalue;
+
+    /* Received a single HTTP header. */
+    vname   = nghttp3_rcbuf_get_buf(name);
+    vvalue  = nghttp3_rcbuf_get_buf(value);
+
+    fwrite(vname.base, vname.len, 1, stderr);
+    fprintf(stderr, ": ");
+    fwrite(vvalue.base, vvalue.len, 1, stderr);
+    fprintf(stderr, "\n");
+
+    return 0;
+}
+
+static int on_end_headers(nghttp3_conn *h3conn, int64_t stream_id,
+                          int fin,
+                          void *conn_user_data, void *stream_user_data)
+{
+    fprintf(stderr, "\n");
+    return 0;
+}
+
+static int on_recv_data(nghttp3_conn *h3conn, int64_t stream_id,
+                        const uint8_t *data, size_t datalen,
+                        void *conn_user_data, void *stream_user_data)
+{
+    ssize_t wr;
+
+    /* HTTP response body data - write it to stdout. */
+    while (datalen > 0) {
+        wr = fwrite(data, 1, datalen, stdout);
+        if (wr < 0)
+            return 1;
+
+        data    += wr;
+        datalen -= wr;
+    }
+
+    return 0;
+}
+
+static int on_end_stream(nghttp3_conn *h3conn, int64_t stream_id,
+                         void *conn_user_data, void *stream_user_data)
+{
+    /* HTTP transaction is done - set done flag so that we stop looping. */
+    done = 1;
+    return 0;
+}
+
+int main(int argc, char **argv)
+{
+    int ret = 1;
+    SSL_CTX *ctx = NULL;
+    H3_CONN *conn = NULL;
+    nghttp3_nv nva[16];
+    nghttp3_callbacks callbacks = {0};
+    size_t num_nv = 0;
+    const char *addr;
+
+    /* Check arguments. */
+    if (argc < 2) {
+        fprintf(stderr, "usage: %s <host:port>\n", argv[0]);
+        goto err;
+    }
+
+    addr = argv[1];
+
+    /* Setup SSL_CTX. */
+    if ((ctx = SSL_CTX_new(OSSL_QUIC_client_method())) == NULL)
+        goto err;
+
+    SSL_CTX_set_verify(ctx, SSL_VERIFY_PEER, NULL);
+
+    if (SSL_CTX_set_default_verify_paths(ctx) == 0)
+        goto err;
+
+    /* Setup callbacks. */
+    callbacks.recv_header   = on_recv_header;
+    callbacks.end_headers   = on_end_headers;
+    callbacks.recv_data     = on_recv_data;
+    callbacks.end_stream    = on_end_stream;
+
+    /* Create connection. */
+    if ((conn = H3_CONN_new_for_addr(ctx, addr, &callbacks,
+                                     NULL, NULL)) == NULL) {
+        ERR_raise_data(ERR_LIB_USER, ERR_R_OPERATION_FAIL,
+                       "cannot create HTTP/3 connection");
+        goto err;
+    }
+
+    /* Build HTTP headers. */
+    make_nv(&nva[num_nv++], ":method", "GET");
+    make_nv(&nva[num_nv++], ":scheme", "https");
+    make_nv(&nva[num_nv++], ":authority", addr);
+    make_nv(&nva[num_nv++], ":path", "/");
+    make_nv(&nva[num_nv++], "user-agent", "OpenSSL-Demo/nghttp3");
+
+    /* Submit request. */
+    if (!H3_CONN_submit_request(conn, nva, num_nv, NULL, NULL)) {
+        ERR_raise_data(ERR_LIB_USER, ERR_R_OPERATION_FAIL,
+                       "cannot submit HTTP/3 request");
+        goto err;
+    }
+
+    /* Wait for request to complete. */
+    while (!done)
+        if (!H3_CONN_handle_events(conn)) {
+            ERR_raise_data(ERR_LIB_USER, ERR_R_OPERATION_FAIL,
+                           "cannot handle events");
+            goto err;
+        }
+
+    ret = 0;
+err:
+    if (ret != 0)
+        ERR_print_errors_fp(stderr);
+
+    H3_CONN_free(conn);
+    SSL_CTX_free(ctx);
+    return ret;
+}
diff --git a/demos/http3/ossl-nghttp3.c b/demos/http3/ossl-nghttp3.c
new file mode 100644
index 0000000000..97bf8baec3
--- /dev/null
+++ b/demos/http3/ossl-nghttp3.c
@@ -0,0 +1,603 @@
+#include "ossl-nghttp3.h"
+#include <openssl/err.h>
+#include <assert.h>
+
+#define ARRAY_LEN(x) (sizeof(x)/sizeof((x)[0]))
+
+enum {
+    H3_STREAM_TYPE_CTRL_SEND,
+    H3_STREAM_TYPE_QPACK_ENC_SEND,
+    H3_STREAM_TYPE_QPACK_DEC_SEND,
+    H3_STREAM_TYPE_REQ,
+};
+
+#define BUF_SIZE    4096
+
+struct h3_stream_st {
+    uint64_t            id;             /* QUIC stream ID */
+    SSL                 *s;             /* QUIC stream SSL object */
+    int                 done_recv_fin;  /* Received FIN */
+    void                *user_data;
+
+    uint8_t             buf[BUF_SIZE];
+    size_t              buf_cur, buf_total;
+};
+
+DEFINE_LHASH_OF_EX(H3_STREAM);
+
+static void h3_stream_free(H3_STREAM *s)
+{
+    if (s == NULL)
+        return;
+
+    SSL_free(s->s);
+    OPENSSL_free(s);
+}
+
+static unsigned long h3_stream_hash(const H3_STREAM *s)
+{
+    return (unsigned long)s->id;
+}
+
+static int h3_stream_eq(const H3_STREAM *a, const H3_STREAM *b)
+{
+    if (a->id < b->id) return -1;
+    if (a->id > b->id) return 1;
+    return 0;
+}
+
+void *H3_STREAM_get_user_data(const H3_STREAM *s)
+{
+    return s->user_data;
+}
+
+struct h3_conn_st {
+    SSL                 *qconn;         /* QUIC connection SSL object */
+    BIO                 *qconn_bio;     /* BIO wrapping QCSO */
+    nghttp3_conn        *h3conn;        /* HTTP/3 connection object */
+    LHASH_OF(H3_STREAM) *streams;       /* map of stream IDs to H3_STREAMs */
+    void                *user_data;     /* opaque user data pointer */
+
+    int                 pump_res;
+    size_t              consumed_app_data;
+
+    /* Forwarding callbacks */
+    nghttp3_recv_data           recv_data_cb;
+    nghttp3_stream_close        stream_close_cb;
+    nghttp3_stop_sending        stop_sending_cb;
+    nghttp3_reset_stream        reset_stream_cb;
+    nghttp3_deferred_consume    deferred_consume_cb;
+};
+
+void H3_CONN_free(H3_CONN *conn)
+{
+    if (conn == NULL)
+        return;
+
+    lh_H3_STREAM_doall(conn->streams, h3_stream_free);
+
+    nghttp3_conn_del(conn->h3conn);
+    BIO_free_all(conn->qconn_bio);
+    lh_H3_STREAM_free(conn->streams);
+    OPENSSL_free(conn);
+}
+
+static H3_STREAM *h3_conn_create_stream(H3_CONN *conn, int type)
+{
+    H3_STREAM *s;
+    uint64_t flags = SSL_STREAM_FLAG_ADVANCE;
+
+    if ((s = OPENSSL_zalloc(sizeof(H3_STREAM))) == NULL)
+        return NULL;
+
+    if (type != H3_STREAM_TYPE_REQ)
+        flags |= SSL_STREAM_FLAG_UNI;
+
+    if ((s->s = SSL_new_stream(conn->qconn, flags)) == NULL) {
+        ERR_raise_data(ERR_LIB_USER, ERR_R_INTERNAL_ERROR,
+                       "could not create QUIC stream object");
+        goto err;
+    }
+
+    s->id   = SSL_get_stream_id(s->s);
+    lh_H3_STREAM_insert(conn->streams, s);
+    return s;
+
+err:
+    OPENSSL_free(s);
+    return NULL;
+}
+
+static H3_STREAM *h3_conn_accept_stream(H3_CONN *conn, SSL *qstream)
+{
+    H3_STREAM *s;
+
+    if ((s = OPENSSL_zalloc(sizeof(H3_STREAM))) == NULL)
+        return NULL;
+
+    s->id   = SSL_get_stream_id(qstream);
+    s->s    = qstream;
+    lh_H3_STREAM_insert(conn->streams, s);
+    return s;
+}
+
+static void h3_conn_remove_stream(H3_CONN *conn, H3_STREAM *s)
+{
+    if (s == NULL)
+        return;
+
+    lh_H3_STREAM_delete(conn->streams, s);
+    h3_stream_free(s);
+}
+
+static int h3_conn_recv_data(nghttp3_conn *h3conn, int64_t stream_id,
+                             const uint8_t *data, size_t datalen,
+                             void *conn_user_data, void *stream_user_data)
+{
+    H3_CONN *conn = conn_user_data;
+
+    conn->consumed_app_data += datalen;
+    if (conn->recv_data_cb == NULL)
+        return 0;
+
+    return conn->recv_data_cb(h3conn, stream_id, data, datalen,
+                              conn_user_data, stream_user_data);
+}
+
+static int h3_conn_stream_close(nghttp3_conn *h3conn, int64_t stream_id,
+                                uint64_t app_error_code,
+                                void *conn_user_data, void *stream_user_data)
+{
+    int ret = 0;
+    H3_CONN *conn = conn_user_data;
+    H3_STREAM *stream = stream_user_data;
+
+    if (conn->stream_close_cb != NULL)
+        ret = conn->stream_close_cb(h3conn, stream_id, app_error_code,
+                                    conn_user_data, stream_user_data);
+
+    h3_conn_remove_stream(conn, stream);
+    return ret;
+}
+
+static int h3_conn_stop_sending(nghttp3_conn *h3conn, int64_t stream_id,
+                                uint64_t app_error_code,
+                                void *conn_user_data, void *stream_user_data)
+{
+    int ret = 0;
+    H3_CONN *conn = conn_user_data;
+    H3_STREAM *stream = stream_user_data;
+
+    if (conn->stop_sending_cb != NULL)
+        ret = conn->stop_sending_cb(h3conn, stream_id, app_error_code,
+                                    conn_user_data, stream_user_data);
+
+    SSL_free(stream->s);
+    stream->s = NULL;
+    return ret;
+}
+
+static int h3_conn_reset_stream(nghttp3_conn *h3conn, int64_t stream_id,
+                                uint64_t app_error_code,
+                                void *conn_user_data, void *stream_user_data)
+{
+    int ret = 0;
+    H3_CONN *conn = conn_user_data;
+    H3_STREAM *stream = stream_user_data;
+    SSL_STREAM_RESET_ARGS args = {0};
+
+    if (conn->reset_stream_cb != NULL)
+        ret = conn->reset_stream_cb(h3conn, stream_id, app_error_code,
+                                   conn_user_data, stream_user_data);
+
+    if (stream->s != NULL) {
+        args.quic_error_code = app_error_code;
+
+        if (!SSL_stream_reset(stream->s, &args, sizeof(args)))
+            return 1;
+    }
+
+    return ret;
+}
+
+static int h3_conn_deferred_consume(nghttp3_conn *h3conn, int64_t stream_id,
+                                    size_t consumed,
+                                    void *conn_user_data, void *stream_user_data)
+{
+    int ret = 0;
+    H3_CONN *conn = conn_user_data;
+
+    if (conn->deferred_consume_cb != NULL)
+        ret = conn->deferred_consume_cb(h3conn, stream_id, consumed,
+                                        conn_user_data, stream_user_data);
+
+    conn->consumed_app_data += consumed;
+    return ret;
+}
+
+H3_CONN *H3_CONN_new_for_conn(BIO *qconn_bio,
+                              const nghttp3_callbacks *callbacks,
+                              const nghttp3_settings *settings,
+                              void *user_data)
+{
+    int ec;
+    H3_CONN *conn;
+    H3_STREAM *s_ctl_send = NULL, *s_qpenc_send = NULL, *s_qpdec_send = NULL;
+    nghttp3_settings dsettings = {0};
+    nghttp3_callbacks intl_callbacks = {0};
+    static const unsigned char alpn[] = {2, 'h', '3'};
+
+    if (qconn_bio == NULL) {
+        ERR_raise_data(ERR_LIB_USER, ERR_R_PASSED_NULL_PARAMETER,
+                       "QUIC connection BIO must be provided");
+        return NULL;
+    }
+
+    if ((conn = OPENSSL_zalloc(sizeof(H3_CONN))) == NULL)
+        return NULL;
+
+    conn->qconn_bio = qconn_bio;
+    conn->user_data = user_data;
+
+    if (BIO_get_ssl(qconn_bio, &conn->qconn) == 0) {
+        ERR_raise_data(ERR_LIB_USER, ERR_R_PASSED_INVALID_ARGUMENT,
+                       "BIO must be an SSL BIO");
+        goto err;
+    }
+
+    if ((conn->streams = lh_H3_STREAM_new(h3_stream_hash, h3_stream_eq)) == NULL)
+        goto err;
+
+    if (SSL_in_before(conn->qconn))
+        if (SSL_set_alpn_protos(conn->qconn, alpn, sizeof(alpn))) {
+            /* SSL_set_alpn_protos returns 1 on failure */
+            ERR_raise_data(ERR_LIB_USER, ERR_R_INTERNAL_ERROR,
+                           "failed to configure ALPN");
+            goto err;
+        }
+
+    BIO_set_nbio(conn->qconn_bio, 1);
+
+    if (!SSL_set_default_stream_mode(conn->qconn, SSL_DEFAULT_STREAM_MODE_NONE)) {
+        ERR_raise_data(ERR_LIB_USER, ERR_R_INTERNAL_ERROR,
+                       "failed to configure default stream mode");
+        goto err;
+    }
+
+    if ((s_ctl_send = h3_conn_create_stream(conn, H3_STREAM_TYPE_CTRL_SEND)) == NULL)
+        goto err;
+
+    if ((s_qpenc_send = h3_conn_create_stream(conn, H3_STREAM_TYPE_QPACK_ENC_SEND)) == NULL)
+        goto err;
+
+    if ((s_qpdec_send = h3_conn_create_stream(conn, H3_STREAM_TYPE_QPACK_DEC_SEND)) == NULL)
+        goto err;
+
+    if (settings == NULL) {
+        nghttp3_settings_default(&dsettings);
+        settings = &dsettings;
+    }
+
+    if (callbacks != NULL)
+        intl_callbacks = *callbacks;
+
+    conn->recv_data_cb          = intl_callbacks.recv_data;
+    conn->stream_close_cb       = intl_callbacks.stream_close;
+    conn->stop_sending_cb       = intl_callbacks.stop_sending;
+    conn->reset_stream_cb       = intl_callbacks.reset_stream;
+    conn->deferred_consume_cb   = intl_callbacks.deferred_consume;
+
+    intl_callbacks.recv_data        = h3_conn_recv_data;
+    intl_callbacks.stream_close     = h3_conn_stream_close;
+    intl_callbacks.stop_sending     = h3_conn_stop_sending;
+    intl_callbacks.reset_stream     = h3_conn_reset_stream;
+    intl_callbacks.deferred_consume = h3_conn_deferred_consume;
+
+    ec = nghttp3_conn_client_new(&conn->h3conn, &intl_callbacks, settings,
+                                 NULL, conn);
+    if (ec < 0) {
+        ERR_raise_data(ERR_LIB_USER, ERR_R_INTERNAL_ERROR,
+                       "cannot create nghttp3 connection: %s (%d)",
+                       nghttp3_strerror(ec), ec);
+        goto err;
+    }
+
+    ec = nghttp3_conn_bind_control_stream(conn->h3conn, s_ctl_send->id);
+    if (ec < 0) {
+        ERR_raise_data(ERR_LIB_USER, ERR_R_INTERNAL_ERROR,
+                       "cannot bind nghttp3 control stream: %s (%d)",
+                       nghttp3_strerror(ec), ec);
+        goto err;
+    }
+
+    ec = nghttp3_conn_bind_qpack_streams(conn->h3conn,
+                                         s_qpenc_send->id,
+                                         s_qpdec_send->id);
+    if (ec < 0) {
+        ERR_raise_data(ERR_LIB_USER, ERR_R_INTERNAL_ERROR,
+                       "cannot bind nghttp3 QPACK streams: %s (%d)",
+                       nghttp3_strerror(ec), ec);
+        goto err;
+    }
+
+    return conn;
+
+err:
+    nghttp3_conn_del(conn->h3conn);
+    h3_stream_free(s_ctl_send);
+    h3_stream_free(s_qpenc_send);
+    h3_stream_free(s_qpdec_send);
+    lh_H3_STREAM_free(conn->streams);
+    OPENSSL_free(conn);
+    return NULL;
+}
+
+H3_CONN *H3_CONN_new_for_addr(SSL_CTX *ctx, const char *addr,
+                              const nghttp3_callbacks *callbacks,
+                              const nghttp3_settings *settings,
+                              void *user_data)
+{
+    BIO *qconn_bio = NULL;
+    SSL *qconn = NULL;
+    H3_CONN *conn = NULL;
+    const char *bare_hostname;
+
+    /* QUIC connection setup */
+    if ((qconn_bio = BIO_new_ssl_connect(ctx)) == NULL)
+        goto err;
+
+    if (BIO_set_conn_hostname(qconn_bio, addr) == 0)
+        goto err;
+
+    bare_hostname = BIO_get_conn_hostname(qconn_bio);
+    if (bare_hostname == NULL)
+        goto err;
+
+    if (BIO_get_ssl(qconn_bio, &qconn) == 0)
+        goto err;
+
+    if (SSL_set1_host(qconn, bare_hostname) <= 0)
+        goto err;
+
+    conn = H3_CONN_new_for_conn(qconn_bio, callbacks, settings, user_data);
+    if (conn == NULL)
+        goto err;
+
+    return conn;
+
+err:
+    BIO_free_all(qconn_bio);
+    return NULL;
+}
+
+int H3_CONN_connect(H3_CONN *conn)
+{
+    return SSL_connect(H3_CONN_get0_connection(conn));
+}
+
+void *H3_CONN_get_user_data(const H3_CONN *conn)
+{
+    return conn->user_data;
+}
+
+SSL *H3_CONN_get0_connection(const H3_CONN *conn)
+{
+    return conn->qconn;
+}
+
+/* Pumps received data to the HTTP/3 stack for a single stream. */
+static void h3_conn_pump_stream(H3_STREAM *s, void *conn_)
+{
+    int ec;
+    H3_CONN *conn = conn_;
+    size_t num_bytes, consumed;
+    uint64_t aec;
+
+    if (!conn->pump_res)
+        return;
+
+    for (;;) {
+        if (s->s == NULL
+            || SSL_get_stream_read_state(s->s) == SSL_STREAM_STATE_WRONG_DIR
+            || s->done_recv_fin)
+            break;
+
+        /*
+         * Pump data from OpenSSL QUIC to the HTTP/3 stack by calling SSL_peek
+         * to get received data and passing it to nghttp3 using
+         * nghttp3_conn_read_stream. Note that this function is confusingly
+         * named and inputs data to the HTTP/3 stack.
+         */
+        if (s->buf_cur == s->buf_total) {
+            /* Need more data. */
+            ec = SSL_read_ex(s->s, s->buf, sizeof(s->buf), &num_bytes);
+            if (ec <= 0) {
+                num_bytes = 0;
+                if (SSL_get_error(s->s, ec) == SSL_ERROR_ZERO_RETURN) {
+                    /* Stream concluded normally. Pass FIN to HTTP/3 stack. */
+                    ec = nghttp3_conn_read_stream(conn->h3conn, s->id, NULL, 0,
+                                                  /*fin=*/1);
+                    if (ec < 0) {
+                        ERR_raise_data(ERR_LIB_USER, ERR_R_INTERNAL_ERROR,
+                                       "cannot pass FIN to nghttp3: %s (%d)",
+                                       nghttp3_strerror(ec), ec);
+                        goto err;
+                    }
+
+                    s->done_recv_fin = 1;
+                } else if (SSL_get_stream_read_state(s->s)
+                            == SSL_STREAM_STATE_RESET_REMOTE) {
+                    /* Stream was reset by peer. */
+                    if (!SSL_get_stream_read_error_code(s->s, &aec))
+                        goto err;
+
+                    ec = nghttp3_conn_close_stream(conn->h3conn, s->id, aec);
+                    if (ec < 0) {
+                        ERR_raise_data(ERR_LIB_USER, ERR_R_INTERNAL_ERROR,
+                                       "cannot mark stream as reset: %s (%d)",
+                                       nghttp3_strerror(ec), ec);
+                        goto err;
+                    }
+
+                    s->done_recv_fin = 1;
+                } else {
+                    /* Other error. */
+                    goto err;
+                }
+            }
+
+            s->buf_cur      = 0;
+            s->buf_total    = num_bytes;
+        }
+
+        if (s->buf_cur == s->buf_total)
+            break;
+
+        assert(conn->consumed_app_data == 0);
+        ec = nghttp3_conn_read_stream(conn->h3conn, s->id, s->buf + s->buf_cur,
+                                      s->buf_total - s->buf_cur, /*fin=*/0);
+        if (ec < 0) {
+            ERR_raise_data(ERR_LIB_USER, ERR_R_INTERNAL_ERROR,
+                           "nghttp3 failed to process incoming data: %s (%d)",
+                           nghttp3_strerror(ec), ec);
+            goto err;
+        }
+
+        consumed = ec + conn->consumed_app_data;
+        assert(consumed <= s->buf_total - s->buf_cur);
+        s->buf_cur += consumed;
+        conn->consumed_app_data = 0;
+    }
+
+    return;
+err:
+    conn->pump_res = 0;
+}
+
+int H3_CONN_handle_events(H3_CONN *conn)
+{
+    int ec, fin;
+    size_t i, num_vecs, written, total_written, total_len;
+    int64_t stream_id;
+    nghttp3_vec vecs[8] = {0};
+    H3_STREAM key, *s;
+    SSL *snew;
+
+    if (conn == NULL)
+        return 0;
+
+    /* Check for new incoming streams */
+    for (;;) {
+        if ((snew = SSL_accept_stream(conn->qconn, SSL_ACCEPT_STREAM_NO_BLOCK)) == NULL)
+            break;
+
+        if (h3_conn_accept_stream(conn, snew) == NULL) {
+            SSL_free(snew);
+            return 0;
+        }
+    }
+
+    /* Pump outgoing data from HTTP/3 engine to QUIC. */
+    for (;;) {
+        /* Get a number of send vectors from the HTTP/3 engine. */
+        ec = nghttp3_conn_writev_stream(conn->h3conn, &stream_id, &fin,
+                                        vecs, ARRAY_LEN(vecs));
+        if (ec < 0)
+            return 0;
+        if (ec == 0)
+            break;
+
+        /* For each of the vectors returned, pass it to OpenSSL QUIC. */
+        key.id = stream_id;
+        if ((s = lh_H3_STREAM_retrieve(conn->streams, &key)) == NULL) {
+            ERR_raise_data(ERR_LIB_USER, ERR_R_INTERNAL_ERROR,
+                           "no stream for ID %zd", stream_id);
+            return 0;
+        }
+
+        num_vecs = ec;
+        total_len = nghttp3_vec_len(vecs, num_vecs);
+        total_written = 0;
+        for (i = 0; i < num_vecs; ++i) {
+            if (vecs[i].len == 0)
+                continue;
+
+            if (s->s == NULL) {
+                written = vecs[i].len;
+            } else if (!SSL_write_ex(s->s, vecs[i].base, vecs[i].len, &written)) {
+                if (SSL_get_error(s->s, 0) == SSL_ERROR_WANT_WRITE) {
+                    written = 0;
+                    nghttp3_conn_block_stream(conn->h3conn, stream_id);
+                } else {
+                    ERR_raise_data(ERR_LIB_USER, ERR_R_INTERNAL_ERROR,
+                                   "writing HTTP/3 data to network failed");
+                    return 0;
+                }
+            } else {
+                nghttp3_conn_unblock_stream(conn->h3conn, stream_id);
+            }
+
+            total_written += written;
+            if (written > 0) {
+                ec = nghttp3_conn_add_write_offset(conn->h3conn, stream_id, written);
+                if (ec < 0)
+                    return 0;
+
+                ec = nghttp3_conn_add_ack_offset(conn->h3conn, stream_id, written);
+                if (ec < 0)
+                    return 0;
+            }
+        }
+
+        if (fin && total_written == total_len) {
+            SSL_stream_conclude(s->s, 0);
+            if (total_len == 0) {
+                ec = nghttp3_conn_add_write_offset(conn->h3conn, stream_id, 0);
+                if (ec < 0)
+                    return 0;
+            }
+        }
+    }
+
+    /* Pump incoming data from QUIC to HTTP/3 engine. */
+    conn->pump_res = 1;
+    lh_H3_STREAM_doall_arg(conn->streams, h3_conn_pump_stream, conn);
+    if (!conn->pump_res)
+        return 0;
+
+    return 1;
+}
+
+int H3_CONN_submit_request(H3_CONN *conn, const nghttp3_nv *nva, size_t nvlen,
+                           const nghttp3_data_reader *dr,
+                           void *user_data)
+{
+    int ec;
+    H3_STREAM *s_req = NULL;
+
+    if (conn == NULL) {
+        ERR_raise_data(ERR_LIB_USER, ERR_R_PASSED_NULL_PARAMETER,
+                       "connection must be specified");
+        return 0;
+    }
+
+    if ((s_req = h3_conn_create_stream(conn, H3_STREAM_TYPE_REQ)) == NULL)
+        goto err;
+
+    s_req->user_data = user_data;
+
+    ec = nghttp3_conn_submit_request(conn->h3conn, s_req->id, nva, nvlen,
+                                     dr, s_req);
+    if (ec < 0) {
+        ERR_raise_data(ERR_LIB_USER, ERR_R_INTERNAL_ERROR,
+                       "cannot submit HTTP/3 request: %s (%d)",
+                       nghttp3_strerror(ec), ec);
+        goto err;
+    }
+
+    return 1;
+
+err:
+    h3_conn_remove_stream(conn, s_req);
+    return 0;
+}
diff --git a/demos/http3/ossl-nghttp3.h b/demos/http3/ossl-nghttp3.h
new file mode 100644
index 0000000000..5013354947
--- /dev/null
+++ b/demos/http3/ossl-nghttp3.h
@@ -0,0 +1,96 @@
+#ifndef OSSL_NGHTTP3_H
+# define OSSL_NGHTTP3_H
+
+# include <openssl/bio.h>
+# include <openssl/ssl.h>
+# include <nghttp3/nghttp3.h>
+
+/*
+ * ossl-nghttp3: Demo binding of nghttp3 to OpenSSL QUIC
+ * =====================================================
+ *
+ * This is a simple library which provides an example binding of the nghttp3
+ * HTTP/3 library to OpenSSL's QUIC API.
+ */
+
+/* Represents an HTTP/3 connection to a server. */
+typedef struct h3_conn_st H3_CONN;
+
+/* Represents an HTTP/3 request, control or QPACK stream. */
+typedef struct h3_stream_st H3_STREAM;
+
+/*
+ * Creates a HTTP/3 connection using the given QUIC client connection BIO. The
+ * BIO must be able to provide an SSL object pointer using BIO_get_ssl. Takes
+ * ownership of the reference. If the QUIC connection SSL object has not already
+ * been connected, HTTP/3 ALPN is set automatically. If it has already been
+ * connected, HTTP/3 ALPN ("h3") must have been configured and no streams must
+ * have been created yet.
+ *
+ * If settings is NULL, use default settings only. Settings unsupported by
+ * this QUIC binding are ignored.
+ *
+ * user_data is an application-provided opaque value which can be retrieved
+ * using H3_CONN_get_user_data. Note that the user data value passed to the
+ * callback functions specified in callbacks is a pointer to the H3_CONN, not
+ * user_data.
+ *
+ * Returns NULL on failure.
+ */
+H3_CONN *H3_CONN_new_for_conn(BIO *qconn_bio,
+                              const nghttp3_callbacks *callbacks,
+                              const nghttp3_settings *settings,
+                              void *user_data);
+
+/*
+ * Works identically to H3_CONN_new_for_conn except that it manages the creation
+ * of a QUIC connection SSL object automatically using an address string. addr
+ * should be a string such as "www.example.com:443". The created underlying QUIC
+ * connection SSL object is owned by the H3_CONN and can be subsequently
+ * retrieved using H3_CONN_get0_connection.
+ *
+ * Returns NULL on failure. ctx must be a SSL_CTX using a QUIC client
+ * SSL_METHOD.
+ */
+H3_CONN *H3_CONN_new_for_addr(SSL_CTX *ctx, const char *addr,
+                              const nghttp3_callbacks *callbacks,
+                              const nghttp3_settings *settings,
+                              void *user_data);
+
+/* Equivalent to SSL_connect(H3_CONN_get0_connection(conn)). */
+int H3_CONN_connect(H3_CONN *conn);
+
+/*
+ * Free the H3_CONN and any underlying QUIC connection SSL object and associated
+ * streams.
+ */
+void H3_CONN_free(H3_CONN *conn);
+
+/* Returns the user data value which was specified in H3_CONN_new_for_conn. */
+void *H3_CONN_get_user_data(const H3_CONN *conn);
+
+/* Returns the underlying QUIC connection SSL object. */
+SSL *H3_CONN_get0_connection(const H3_CONN *conn);
+
+/*
+ * Handle any pending events on a given HTTP/3 connection. Returns 0 on error.
+ */
+int H3_CONN_handle_events(H3_CONN *conn);
+
+/*
+ * Submits a new HTTP/3 request on the given connection. Returns 0 on error.
+ *
+ * This works analogously to nghttp3_conn_submit_request(). The stream user data
+ * pointer passed to the callbacks is a H3_STREAM object pointer; to retrieve
+ * the stream user data pointer passed to this function, use
+ * H3_STREAM_get_user_data.
+ */
+int H3_CONN_submit_request(H3_CONN *conn,
+                           const nghttp3_nv *hdr, size_t hdrlen,
+                           const nghttp3_data_reader *dr,
+                           void *stream_user_data);
+
+/* Returns the user data value which was specified in H3_CONN_submit_request. */
+void *H3_STREAM_get_user_data(const H3_STREAM *stream);
+
+#endif