curl/lib/http2.c

/***************************************************************************
 *                                  _   _ ____  _
 *  Project                     ___| | | |  _ \| |
 *                             / __| | | | |_) | |
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) 1998 - 2015, Daniel Stenberg, <daniel@haxx.se>, et al.
 *
 * This software is licensed as described in the file COPYING, which
 * you should have received as part of this distribution. The terms
 * are also available at http://curl.haxx.se/docs/copyright.html.
 *
 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
 * copies of the Software, and permit persons to whom the Software is
 * furnished to do so, under the terms of the COPYING file.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 ***************************************************************************/

#include "curl_setup.h"

#ifdef USE_NGHTTP2
#include "curl_printf.h"
#include <nghttp2/nghttp2.h>
#include "urldata.h"
#include "http2.h"
#include "http.h"
#include "sendf.h"
#include "curl_base64.h"
#include "rawstr.h"
#include "multiif.h"
#include "conncache.h"

/* The last #include files should be: */
#include "curl_memory.h"
#include "memdebug.h"

#define MIN(x,y) ((x)<(y)?(x):(y))

#if (NGHTTP2_VERSION_NUM < 0x000600)
#error too old nghttp2 version, upgrade!
#endif

static int http2_perform_getsock(const struct connectdata *conn,
                                 curl_socket_t *sock, /* points to
                                                         numsocks
                                                         number of
                                                         sockets */
                                 int numsocks)
{
  const struct http_conn *c = &conn->proto.httpc;
  int bitmap = GETSOCK_BLANK;
  (void)numsocks;

  /* TODO We should check underlying socket state if it is SSL socket
     because of renegotiation. */
  sock[0] = conn->sock[FIRSTSOCKET];

  if(nghttp2_session_want_read(c->h2))
    bitmap |= GETSOCK_READSOCK(FIRSTSOCKET);

  if(nghttp2_session_want_write(c->h2))
    bitmap |= GETSOCK_WRITESOCK(FIRSTSOCKET);

  return bitmap;
}

static int http2_getsock(struct connectdata *conn,
                         curl_socket_t *sock, /* points to numsocks
                                                 number of sockets */
                         int numsocks)
{
  return http2_perform_getsock(conn, sock, numsocks);
}

static CURLcode http2_disconnect(struct connectdata *conn,
                                 bool dead_connection)
{
  struct http_conn *c = &conn->proto.httpc;
  (void)dead_connection;

  DEBUGF(infof(conn->data, "HTTP/2 DISCONNECT starts now\n"));

  nghttp2_session_del(c->h2);
  Curl_safefree(c->inbuf);
  Curl_hash_clean(&c->streamsh);

  DEBUGF(infof(conn->data, "HTTP/2 DISCONNECT done\n"));

  return CURLE_OK;
}

/* called from Curl_http_setup_conn */
void Curl_http2_setup_conn(struct connectdata *conn)
{
  conn->proto.httpc.settings.max_concurrent_streams =
    DEFAULT_MAX_CONCURRENT_STREAMS;
}

/*
 * HTTP2 handler interface. This isn't added to the general list of protocols
 * but will be used at run-time when the protocol is dynamically switched from
 * HTTP to HTTP2.
 */
const struct Curl_handler Curl_handler_http2 = {
  "HTTP2",                              /* scheme */
  ZERO_NULL,                            /* setup_connection */
  Curl_http,                            /* do_it */
  Curl_http_done,                       /* done */
  ZERO_NULL,                            /* do_more */
  ZERO_NULL,                            /* connect_it */
  ZERO_NULL,                            /* connecting */
  ZERO_NULL,                            /* doing */
  http2_getsock,                        /* proto_getsock */
  http2_getsock,                        /* doing_getsock */
  ZERO_NULL,                            /* domore_getsock */
  http2_perform_getsock,                /* perform_getsock */
  http2_disconnect,                     /* disconnect */
  ZERO_NULL,                            /* readwrite */
  PORT_HTTP,                            /* defport */
  CURLPROTO_HTTP,                       /* protocol */
  PROTOPT_NONE                          /* flags */
};

const struct Curl_handler Curl_handler_http2_ssl = {
  "HTTP2",                              /* scheme */
  ZERO_NULL,                            /* setup_connection */
  Curl_http,                            /* do_it */
  Curl_http_done,                       /* done */
  ZERO_NULL,                            /* do_more */
  ZERO_NULL,                            /* connect_it */
  ZERO_NULL,                            /* connecting */
  ZERO_NULL,                            /* doing */
  http2_getsock,                        /* proto_getsock */
  http2_getsock,                        /* doing_getsock */
  ZERO_NULL,                            /* domore_getsock */
  http2_perform_getsock,                /* perform_getsock */
  http2_disconnect,                     /* disconnect */
  ZERO_NULL,                            /* readwrite */
  PORT_HTTP,                            /* defport */
  CURLPROTO_HTTPS,                      /* protocol */
  PROTOPT_SSL                           /* flags */
};

/*
 * Store nghttp2 version info in this buffer, Prefix with a space.  Return
 * total length written.
 */
int Curl_http2_ver(char *p, size_t len)
{
  nghttp2_info *h2 = nghttp2_version(0);
  return snprintf(p, len, " nghttp2/%s", h2->version_str);
}

/*
 * The implementation of nghttp2_send_callback type. Here we write |data| with
 * size |length| to the network and return the number of bytes actually
 * written. See the documentation of nghttp2_send_callback for the details.
 */
static ssize_t send_callback(nghttp2_session *h2,
                             const uint8_t *data, size_t length, int flags,
                             void *userp)
{
  struct connectdata *conn = (struct connectdata *)userp;
  struct http_conn *c = &conn->proto.httpc;
  ssize_t written;
  CURLcode result = CURLE_OK;

  (void)h2;
  (void)flags;

  written = ((Curl_send*)c->send_underlying)(conn, FIRSTSOCKET,
                                             data, length, &result);

  if(result == CURLE_AGAIN) {
    return NGHTTP2_ERR_WOULDBLOCK;
  }

  if(written == -1) {
    failf(conn->data, "Failed sending HTTP2 data");
    return NGHTTP2_ERR_CALLBACK_FAILURE;
  }

  if(!written)
    return NGHTTP2_ERR_WOULDBLOCK;

  return written;
}

static int on_frame_recv(nghttp2_session *session, const nghttp2_frame *frame,
                         void *userp)
{
  struct connectdata *conn = (struct connectdata *)userp;
  struct http_conn *httpc = &conn->proto.httpc;
  struct SessionHandle *data_s = NULL;
  struct HTTP *stream = NULL;
  int rv;
  size_t left, ncopy;
  int32_t stream_id = frame->hd.stream_id;

  (void)session;
  (void)frame;
  DEBUGF(infof(conn->data, "on_frame_recv() header %x stream %x\n",
               frame->hd.type, stream_id));

  if(stream_id) {
    /* get the stream from the hash based on Stream ID, stream ID zero is for
       connection-oriented stuff */
    data_s = Curl_hash_pick(&httpc->streamsh, &stream_id,
                            sizeof(stream_id));
    if(!data_s) {
      /* Receiving a Stream ID not in the hash should not happen, this is an
         internal error more than anything else! */
      failf(conn->data, "Received frame on Stream ID: %x not in stream hash!",
            stream_id);
      return NGHTTP2_ERR_CALLBACK_FAILURE;
    }
    stream = data_s->req.protop;
  }

  switch(frame->hd.type) {
  case NGHTTP2_DATA:
    /* If body started on this stream, then receiving DATA is illegal. */
    if(!stream->bodystarted) {
      rv = nghttp2_submit_rst_stream(session, NGHTTP2_FLAG_NONE,
                                     stream_id, NGHTTP2_PROTOCOL_ERROR);

      if(nghttp2_is_fatal(rv)) {
        return NGHTTP2_ERR_CALLBACK_FAILURE;
      }
    }
    break;
  case NGHTTP2_HEADERS:
    if(frame->headers.cat == NGHTTP2_HCAT_REQUEST)
      break;

    if(stream->bodystarted) {
      /* Only valid HEADERS after body started is trailer header,
         which is not fully supported in this code.  If HEADERS is not
         trailer, then it is a PROTOCOL_ERROR. */
      if((frame->hd.flags & NGHTTP2_FLAG_END_STREAM) == 0) {
        rv = nghttp2_submit_rst_stream(session, NGHTTP2_FLAG_NONE,
                                       stream_id, NGHTTP2_PROTOCOL_ERROR);

        if(nghttp2_is_fatal(rv)) {
          return NGHTTP2_ERR_CALLBACK_FAILURE;
        }
      }
      break;
    }

    if(stream->status_code == -1) {
      /* No :status header field means PROTOCOL_ERROR. */
      rv = nghttp2_submit_rst_stream(session, NGHTTP2_FLAG_NONE,
                                     stream_id, NGHTTP2_PROTOCOL_ERROR);

      if(nghttp2_is_fatal(rv)) {
        return NGHTTP2_ERR_CALLBACK_FAILURE;
      }

      break;
    }

    /* Only final status code signals the end of header */
    if(stream->status_code / 100 != 1)
      stream->bodystarted = TRUE;

    stream->status_code = -1;

    Curl_add_buffer(stream->header_recvbuf, "\r\n", 2);

    left = stream->header_recvbuf->size_used - stream->nread_header_recvbuf;
    ncopy = MIN(stream->len, left);

    memcpy(&stream->mem[stream->memlen],
           stream->header_recvbuf->buffer + stream->nread_header_recvbuf,
           ncopy);
    stream->nread_header_recvbuf += ncopy;

    DEBUGF(infof(data_s, "Store %zu bytes headers from stream %x at %p\n",
                 ncopy, stream_id, stream->mem));

    stream->len -= ncopy;
    stream->memlen += ncopy;

    data_s->state.drain++;
    Curl_expire(data_s, 1);
    break;
  case NGHTTP2_PUSH_PROMISE:
    DEBUGF(infof(data_s, "Got PUSH_PROMISE, RST_STREAM it!\n"));
    rv = nghttp2_submit_rst_stream(session, NGHTTP2_FLAG_NONE,
                                   frame->push_promise.promised_stream_id,
                                   NGHTTP2_CANCEL);
    if(nghttp2_is_fatal(rv)) {
      return rv;
    }
    break;
  case NGHTTP2_SETTINGS:
  {
    uint32_t max_conn = httpc->settings.max_concurrent_streams;
    DEBUGF(infof(conn->data, "Got SETTINGS for stream %x!\n", stream_id));
    httpc->settings.max_concurrent_streams =
      nghttp2_session_get_remote_settings(
        session, NGHTTP2_SETTINGS_MAX_CONCURRENT_STREAMS);
    httpc->settings.enable_push =
      nghttp2_session_get_remote_settings(
        session, NGHTTP2_SETTINGS_ENABLE_PUSH);
    DEBUGF(infof(conn->data, "MAX_CONCURRENT_STREAMS == %d\n",
                 httpc->settings.max_concurrent_streams));
    DEBUGF(infof(conn->data, "ENABLE_PUSH == %s\n",
                 httpc->settings.enable_push?"TRUE":"false"));
    if(max_conn != httpc->settings.max_concurrent_streams) {
      /* only signal change if the value actually changed */
      infof(conn->data,
            "Connection state changed (MAX_CONCURRENT_STREAMS updated)!\n");
      Curl_multi_connchanged(conn->data->multi);
    }
  }
  break;
  default:
    DEBUGF(infof(conn->data, "Got frame type %x for stream %x!\n",
                 frame->hd.type, stream_id));
    break;
  }
  return 0;
}

static int on_invalid_frame_recv(nghttp2_session *session,
                                 const nghttp2_frame *frame,
                                 uint32_t error_code, void *userp)
{
  struct connectdata *conn = (struct connectdata *)userp;
  (void)session;
  (void)frame;
  DEBUGF(infof(conn->data,
               "on_invalid_frame_recv() was called, error_code = %d\n",
               error_code));
  return 0;
}

static int on_data_chunk_recv(nghttp2_session *session, uint8_t flags,
                              int32_t stream_id,
                              const uint8_t *data, size_t len, void *userp)
{
  struct connectdata *conn = (struct connectdata *)userp;
  struct HTTP *stream;
  struct SessionHandle *data_s;
  size_t nread;
  (void)session;
  (void)flags;
  (void)data;
  DEBUGF(infof(conn->data, "on_data_chunk_recv() "
               "len = %u, stream %x\n", len, stream_id));

  DEBUGASSERT(stream_id); /* should never be a zero stream ID here */

  /* get the stream from the hash based on Stream ID */
  data_s = Curl_hash_pick(&conn->proto.httpc.streamsh, &stream_id,
                          sizeof(stream_id));
  if(!data_s) {
    /* Receiving a Stream ID not in the hash should not happen, this is an
       internal error more than anything else! */
    failf(conn->data, "Received frame on Stream ID: %x not in stream hash!",
          stream_id);
    return NGHTTP2_ERR_CALLBACK_FAILURE;
  }
  stream = data_s->req.protop;

  nread = MIN(stream->len, len);
  memcpy(&stream->mem[stream->memlen], data, nread);

  stream->len -= nread;
  stream->memlen += nread;

  data_s->state.drain++;
  Curl_expire(data_s, 1); /* TODO: fix so that this can be set to 0 for
                             immediately? */

  DEBUGF(infof(data_s, "%zu data received for stream %x "
               "(%zu left in buffer %p, total %zu)\n",
               nread, stream_id,
               stream->len, stream->mem,
               stream->memlen));

  if(nread < len) {
    stream->pausedata = data + nread;
    stream->pauselen = len - nread;
    DEBUGF(infof(data_s, "NGHTTP2_ERR_PAUSE - %zu bytes out of buffer"
                 ", stream %x\n",
                 len - nread, stream_id));
    conn->proto.httpc.pause_stream_id = stream_id;
    return NGHTTP2_ERR_PAUSE;
  }
  return 0;
}

static int before_frame_send(nghttp2_session *session,
                             const nghttp2_frame *frame,
                             void *userp)
{
  struct connectdata *conn = (struct connectdata *)userp;
  (void)session;
  (void)frame;
  DEBUGF(infof(conn->data, "before_frame_send() was called\n"));
  return 0;
}
static int on_frame_send(nghttp2_session *session,
                         const nghttp2_frame *frame,
                         void *userp)
{
  struct connectdata *conn = (struct connectdata *)userp;
  (void)session;
  (void)frame;
  DEBUGF(infof(conn->data, "on_frame_send() was called\n"));
  return 0;
}
static int on_frame_not_send(nghttp2_session *session,
                             const nghttp2_frame *frame,
                             int lib_error_code, void *userp)
{
  struct connectdata *conn = (struct connectdata *)userp;
  (void)session;
  (void)frame;
  DEBUGF(infof(conn->data,
               "on_frame_not_send() was called, lib_error_code = %d\n",
               lib_error_code));
  return 0;
}
static int on_stream_close(nghttp2_session *session, int32_t stream_id,
                           uint32_t error_code, void *userp)
{
  struct connectdata *conn = (struct connectdata *)userp;
  struct SessionHandle *data_s;
  struct HTTP *stream;
  (void)session;
  (void)stream_id;
  DEBUGF(infof(conn->data, "on_stream_close(), error_code = %d, stream %x\n",
               error_code, stream_id));

  if(stream_id) {
    /* get the stream from the hash based on Stream ID, stream ID zero is for
       connection-oriented stuff */
    data_s = Curl_hash_pick(&conn->proto.httpc.streamsh, &stream_id,
                            sizeof(stream_id));
    if(!data_s) {
      /* Receiving a Stream ID not in the hash should not happen, this is an
         internal error more than anything else! */
      failf(conn->data, "Received frame on Stream ID: %x not in stream hash!",
            stream_id);
      return NGHTTP2_ERR_CALLBACK_FAILURE;
    }
    stream = data_s->req.protop;

    stream->error_code = error_code;
    stream->closed = TRUE;

    /* remove the entry from the hash as the stream is now gone */
    Curl_hash_delete(&conn->proto.httpc.streamsh,
                     &stream_id, sizeof(stream_id));
    DEBUGF(infof(conn->data, "Removed stream %x hash!\n", stream_id));
  }
  return 0;
}

static int on_begin_headers(nghttp2_session *session,
                            const nghttp2_frame *frame, void *userp)
{
  struct connectdata *conn = (struct connectdata *)userp;
  (void)session;
  (void)frame;
  DEBUGF(infof(conn->data, "on_begin_headers() was called\n"));
  return 0;
}

/* Decode HTTP status code.  Returns -1 if no valid status code was
   decoded. */
static int decode_status_code(const uint8_t *value, size_t len)
{
  int i;
  int res;

  if(len != 3) {
    return -1;
  }

  res = 0;

  for(i = 0; i < 3; ++i) {
    char c = value[i];

    if(c < '0' || c > '9') {
      return -1;
    }

    res *= 10;
    res += c - '0';
  }

  return res;
}

static const char STATUS[] = ":status";

/* frame->hd.type is either NGHTTP2_HEADERS or NGHTTP2_PUSH_PROMISE */
static int on_header(nghttp2_session *session, const nghttp2_frame *frame,
                     const uint8_t *name, size_t namelen,
                     const uint8_t *value, size_t valuelen,
                     uint8_t flags,
                     void *userp)
{
  struct connectdata *conn = (struct connectdata *)userp;
  struct HTTP *stream;
  struct SessionHandle *data_s;
  int rv;
  int goodname;
  int goodheader;
  int32_t stream_id = frame->hd.stream_id;

  (void)session;
  (void)frame;
  (void)flags;

  /* Ignore PUSH_PROMISE for now */
  if(frame->hd.type != NGHTTP2_HEADERS) {
    return 0;
  }

  DEBUGASSERT(stream_id); /* should never be a zero stream ID here */

  /* get the stream from the hash based on Stream ID */
  data_s = Curl_hash_pick(&conn->proto.httpc.streamsh, &stream_id,
                          sizeof(stream_id));
  if(!data_s) {
    /* Receiving a Stream ID not in the hash should not happen, this is an
       internal error more than anything else! */
    failf(conn->data, "Received frame on Stream ID: %x not in stream hash!",
          stream_id);
    return NGHTTP2_ERR_CALLBACK_FAILURE;
  }
  stream = data_s->req.protop;

  if(stream->bodystarted)
    /* Ignore trailer or HEADERS not mapped to HTTP semantics.  The
       consequence is handled in on_frame_recv(). */
    return 0;

  goodname = nghttp2_check_header_name(name, namelen);
  goodheader = nghttp2_check_header_value(value, valuelen);

  if(!goodname || !goodheader) {

    infof(data_s, "Detected bad incoming header %s%s, reset stream!\n",
          goodname?"":"name",
          goodheader?"":"value");

    rv = nghttp2_submit_rst_stream(session, NGHTTP2_FLAG_NONE,
                                   stream_id, NGHTTP2_PROTOCOL_ERROR);

    if(nghttp2_is_fatal(rv)) {
      return NGHTTP2_ERR_CALLBACK_FAILURE;
    }

    return NGHTTP2_ERR_TEMPORAL_CALLBACK_FAILURE;
  }

  if(namelen == sizeof(":status") - 1 &&
     memcmp(STATUS, name, namelen) == 0) {

    /* :status must appear exactly once. */
    if(stream->status_code != -1 ||
       (stream->status_code = decode_status_code(value, valuelen)) == -1) {

      rv = nghttp2_submit_rst_stream(session, NGHTTP2_FLAG_NONE,
                                     stream_id, NGHTTP2_PROTOCOL_ERROR);
      if(nghttp2_is_fatal(rv)) {
        return NGHTTP2_ERR_CALLBACK_FAILURE;
      }

      return NGHTTP2_ERR_TEMPORAL_CALLBACK_FAILURE;
    }

    Curl_add_buffer(stream->header_recvbuf, "HTTP/2.0 ", 9);
    Curl_add_buffer(stream->header_recvbuf, value, valuelen);
    Curl_add_buffer(stream->header_recvbuf, "\r\n", 2);
    data_s->state.drain++;
    Curl_expire(data_s, 1);

    DEBUGF(infof(data_s, "h2 status: HTTP/2 %03d\n",
                 stream->status_code));
    return 0;
  }
  else {
    /* Here we are sure that namelen > 0 because of
       nghttp2_check_header_name().  Pseudo header other than :status
       is illegal. */
    if(stream->status_code == -1 || name[0] == ':') {
      rv = nghttp2_submit_rst_stream(session, NGHTTP2_FLAG_NONE,
                                     stream_id, NGHTTP2_PROTOCOL_ERROR);
      if(nghttp2_is_fatal(rv)) {
        return NGHTTP2_ERR_CALLBACK_FAILURE;
      }

      return NGHTTP2_ERR_TEMPORAL_CALLBACK_FAILURE;
    }

    /* convert to a HTTP1-style header */
    Curl_add_buffer(stream->header_recvbuf, name, namelen);
    Curl_add_buffer(stream->header_recvbuf, ":", 1);
    Curl_add_buffer(stream->header_recvbuf, value, valuelen);
    Curl_add_buffer(stream->header_recvbuf, "\r\n", 2);
    data_s->state.drain++;
    Curl_expire(data_s, 1);

    DEBUGF(infof(data_s, "h2 header: %.*s: %.*s\n",
                 namelen, name, valuelen, value));
  }

  return 0; /* 0 is successful */
}

static ssize_t data_source_read_callback(nghttp2_session *session,
                                         int32_t stream_id,
                                         uint8_t *buf, size_t length,
                                         uint32_t *data_flags,
                                         nghttp2_data_source *source,
                                         void *userp)
{
  struct connectdata *conn = (struct connectdata *)userp;
  struct http_conn *c = &conn->proto.httpc;
  size_t nread;
  (void)session;
  (void)stream_id;
  (void)source;

  nread = MIN(c->upload_len, length);
  if(nread > 0) {
    memcpy(buf, c->upload_mem, nread);
    c->upload_mem += nread;
    c->upload_len -= nread;
    c->upload_left -= nread;
  }

  if(c->upload_left == 0)
    *data_flags = 1;
  else if(nread == 0)
    return NGHTTP2_ERR_DEFERRED;

  return nread;
}

/*
 * The HTTP2 settings we send in the Upgrade request
 */
static nghttp2_settings_entry settings[] = {
  { NGHTTP2_SETTINGS_MAX_CONCURRENT_STREAMS, 100 },
  { NGHTTP2_SETTINGS_INITIAL_WINDOW_SIZE, NGHTTP2_INITIAL_WINDOW_SIZE },
};

#define H2_BUFSIZE 32768

static void freestreamentry(void *freethis)
{
  (void)freethis;
}

/*
 * Initialize nghttp2 for a Curl connection
 */
CURLcode Curl_http2_init(struct connectdata *conn)
{
  if(!conn->proto.httpc.h2) {
    int rc;
    nghttp2_session_callbacks *callbacks;

    conn->proto.httpc.inbuf = malloc(H2_BUFSIZE);
    if(conn->proto.httpc.inbuf == NULL)
      return CURLE_OUT_OF_MEMORY;

    rc = nghttp2_session_callbacks_new(&callbacks);

    if(rc) {
      failf(conn->data, "Couldn't initialize nghttp2 callbacks!");
      return CURLE_OUT_OF_MEMORY; /* most likely at least */
    }

    /* nghttp2_send_callback */
    nghttp2_session_callbacks_set_send_callback(callbacks, send_callback);
    /* nghttp2_on_frame_recv_callback */
    nghttp2_session_callbacks_set_on_frame_recv_callback
      (callbacks, on_frame_recv);
    /* nghttp2_on_invalid_frame_recv_callback */
    nghttp2_session_callbacks_set_on_invalid_frame_recv_callback
      (callbacks, on_invalid_frame_recv);
    /* nghttp2_on_data_chunk_recv_callback */
    nghttp2_session_callbacks_set_on_data_chunk_recv_callback
      (callbacks, on_data_chunk_recv);
    /* nghttp2_before_frame_send_callback */
    nghttp2_session_callbacks_set_before_frame_send_callback
      (callbacks, before_frame_send);
    /* nghttp2_on_frame_send_callback */
    nghttp2_session_callbacks_set_on_frame_send_callback
      (callbacks, on_frame_send);
    /* nghttp2_on_frame_not_send_callback */
    nghttp2_session_callbacks_set_on_frame_not_send_callback
      (callbacks, on_frame_not_send);
    /* nghttp2_on_stream_close_callback */
    nghttp2_session_callbacks_set_on_stream_close_callback
      (callbacks, on_stream_close);
    /* nghttp2_on_begin_headers_callback */
    nghttp2_session_callbacks_set_on_begin_headers_callback
      (callbacks, on_begin_headers);
    /* nghttp2_on_header_callback */
    nghttp2_session_callbacks_set_on_header_callback(callbacks, on_header);

    /* The nghttp2 session is not yet setup, do it */
    rc = nghttp2_session_client_new(&conn->proto.httpc.h2, callbacks, conn);

    nghttp2_session_callbacks_del(callbacks);

    if(rc) {
      failf(conn->data, "Couldn't initialize nghttp2!");
      return CURLE_OUT_OF_MEMORY; /* most likely at least */
    }

    rc = Curl_hash_init(&conn->proto.httpc.streamsh, 7, Curl_hash_str,
                        Curl_str_key_compare, freestreamentry);
    if(rc) {
      failf(conn->data, "Couldn't init stream hash!");
      return CURLE_OUT_OF_MEMORY; /* most likely at least */
    }
  }
  return CURLE_OK;
}

/*
 * Send a request using http2
 */
CURLcode Curl_http2_send_request(struct connectdata *conn)
{
  (void)conn;
  return CURLE_OK;
}

/*
 * Append headers to ask for a HTTP1.1 to HTTP2 upgrade.
 */
CURLcode Curl_http2_request_upgrade(Curl_send_buffer *req,
                                    struct connectdata *conn)
{
  CURLcode result;
  ssize_t binlen;
  char *base64;
  size_t blen;
  struct SingleRequest *k = &conn->data->req;
  uint8_t *binsettings = conn->proto.httpc.binsettings;

  /* As long as we have a fixed set of settings, we don't have to dynamically
   * figure out the base64 strings since it'll always be the same. However,
   * the settings will likely not be fixed every time in the future.
   */

  /* this returns number of bytes it wrote */
  binlen = nghttp2_pack_settings_payload(binsettings, H2_BINSETTINGS_LEN,
                                         settings,
                                         sizeof(settings)/sizeof(settings[0]));
  if(!binlen) {
    failf(conn->data, "nghttp2 unexpectedly failed on pack_settings_payload");
    return CURLE_FAILED_INIT;
  }
  conn->proto.httpc.binlen = binlen;

  result = Curl_base64url_encode(conn->data, (const char *)binsettings, binlen,
                                 &base64, &blen);
  if(result)
    return result;

  result = Curl_add_bufferf(req,
                            "Connection: Upgrade, HTTP2-Settings\r\n"
                            "Upgrade: %s\r\n"
                            "HTTP2-Settings: %s\r\n",
                            NGHTTP2_CLEARTEXT_PROTO_VERSION_ID, base64);
  free(base64);

  k->upgr101 = UPGR101_REQUESTED;

  return result;
}

static ssize_t http2_handle_stream_close(struct http_conn *httpc,
                                         struct SessionHandle *data,
                                         struct HTTP *stream, CURLcode *err) {
  if(httpc->pause_stream_id == stream->stream_id) {
    httpc->pause_stream_id = 0;
  }
  /* Reset to FALSE to prevent infinite loop in readwrite_data
   function. */
  stream->closed = FALSE;
  if(stream->error_code != NGHTTP2_NO_ERROR) {
    failf(data, "HTTP/2 stream %x was not closed cleanly: error_code = %d",
          stream->stream_id, stream->error_code);
    *err = CURLE_HTTP2;
    return -1;
  }
  DEBUGF(infof(data, "http2_recv returns 0, http2_handle_stream_close\n"));
  return 0;
}

/*
 * If the read would block (EWOULDBLOCK) we return -1. Otherwise we return
 * a regular CURLcode value.
 */
static ssize_t http2_recv(struct connectdata *conn, int sockindex,
                          char *mem, size_t len, CURLcode *err)
{
  CURLcode result = CURLE_OK;
  ssize_t rv;
  ssize_t nread;
  struct http_conn *httpc = &conn->proto.httpc;
  struct SessionHandle *data = conn->data;
  struct HTTP *stream = data->req.protop;

  (void)sockindex; /* we always do HTTP2 on sockindex 0 */

  /* If stream is closed, return 0 to signal the http routine to close
     the connection.  We need to handle stream closure here,
     otherwise, we may be going to read from underlying connection,
     and gets EAGAIN, and we will get stuck there. */
  if(stream->memlen == 0 && stream->closed) {
    return http2_handle_stream_close(httpc, data, stream, err);
  }

  /* Nullify here because we call nghttp2_session_send() and they
     might refer to the old buffer. */
  httpc->upload_mem = NULL;
  httpc->upload_len = 0;

  /*
   * At this point 'stream' is just in the SessionHandle the connection
   * identifies as its owner at this time.
   */

  if(stream->bodystarted &&
     stream->nread_header_recvbuf < stream->header_recvbuf->size_used) {
    /* If there is body data pending for this stream to return, do that */
    size_t left =
      stream->header_recvbuf->size_used - stream->nread_header_recvbuf;
    size_t ncopy = MIN(len, left);
    memcpy(mem, stream->header_recvbuf->buffer + stream->nread_header_recvbuf,
           ncopy);
    stream->nread_header_recvbuf += ncopy;

    infof(data, "http2_recv: Got %d bytes from header_recvbuf\n",
          (int)ncopy);
    return ncopy;
  }

  infof(data, "http2_recv: %d bytes buffer at %p (stream %x)\n",
        len, mem, stream->stream_id);

  if((data->state.drain) && stream->memlen) {
    DEBUGF(infof(data, "http2_recv: DRAIN %zu bytes stream %x!! (%p => %p)\n",
                 stream->memlen, stream->stream_id,
                 stream->mem, mem));
    if(mem != stream->mem) {
      /* if we didn't get the same buffer this time, we must move the data to
         the beginning */
      memmove(mem, stream->mem, stream->memlen);
      stream->len = len - stream->memlen;
      stream->mem = mem;
    }
  }
  else if(stream->pausedata) {
    nread = MIN(len, stream->pauselen);
    memcpy(mem, stream->pausedata, nread);

    stream->pausedata += nread;
    stream->pauselen -= nread;

    infof(data, "%zu data bytes written\n", nread);
    if(stream->pauselen == 0) {
      DEBUGF(infof(data, "Unpaused by stream %x\n", stream->stream_id));
      assert(httpc->pause_stream_id == stream->stream_id);
      httpc->pause_stream_id = 0;

      stream->pausedata = NULL;
      stream->pauselen = 0;
    }
    infof(data, "http2_recv: returns unpaused %zd bytes on stream %x\n",
          nread, stream->stream_id);
    return nread;
  }
  else if(httpc->pause_stream_id) {
    /* If a stream paused nghttp2_session_mem_recv previously, and has
       not processed all data, it still refers to the buffer in
       nghttp2_session.  If we call nghttp2_session_mem_recv(), we may
       overwrite that buffer.  To avoid that situation, just return
       here with CURLE_AGAIN.  This could be busy loop since data in
       socket is not read.  But it seems that usually streams are
       notified with its drain property, and socket is read again
       quickly. */
    *err = CURLE_AGAIN;
    return -1;
  }
  else {
    char *inbuf;
    /* remember where to store incoming data for this stream and how big the
       buffer is */
    stream->mem = mem;
    stream->len = len;
    stream->memlen = 0;

    if(httpc->inbuflen == 0) {
      nread = ((Curl_recv *)httpc->recv_underlying)(
          conn, FIRSTSOCKET, httpc->inbuf, H2_BUFSIZE, &result);

      if(result == CURLE_AGAIN) {
        *err = result;
        return -1;
      }

      if(nread == -1) {
        failf(data, "Failed receiving HTTP2 data");
        *err = result;
        return 0;
      }

      if(nread == 0) {
        failf(data, "Unexpected EOF");
        *err = CURLE_RECV_ERROR;
        return -1;
      }

      DEBUGF(infof(data, "nread=%zd\n", nread));

      httpc->inbuflen = nread;
      inbuf = httpc->inbuf;
    }
    else {
      nread = httpc->inbuflen - httpc->nread_inbuf;
      inbuf = httpc->inbuf + httpc->nread_inbuf;

      DEBUGF(infof(data, "Use data left in connection buffer, nread=%zd\n",
                   nread));
    }
    rv = nghttp2_session_mem_recv(httpc->h2, (const uint8_t *)inbuf, nread);

    if(nghttp2_is_fatal((int)rv)) {
      failf(data, "nghttp2_session_mem_recv() returned %d:%s\n",
            rv, nghttp2_strerror((int)rv));
      *err = CURLE_RECV_ERROR;
      return 0;
    }
    DEBUGF(infof(data, "nghttp2_session_mem_recv() returns %zd\n", rv));
    if(nread == rv) {
      DEBUGF(infof(data, "All data in connection buffer processed\n"));
      httpc->inbuflen = 0;
      httpc->nread_inbuf = 0;
    }
    else {
      httpc->nread_inbuf += rv;
      DEBUGF(infof(data, "%zu bytes left in connection buffer\n",
                   httpc->inbuflen - httpc->nread_inbuf));
    }
    /* Always send pending frames in nghttp2 session, because
       nghttp2_session_mem_recv() may queue new frame */
    rv = nghttp2_session_send(httpc->h2);
    if(rv != 0) {
      *err = CURLE_SEND_ERROR;
      return 0;
    }
  }
  if(stream->memlen) {
    ssize_t retlen = stream->memlen;
    infof(data, "http2_recv: returns %zd for stream %x\n",
          retlen, stream->stream_id);
    stream->memlen = 0;

    if(httpc->pause_stream_id == stream->stream_id) {
      /* data for this stream is returned now, but this stream caused a pause
         already so we need it called again asap */
      DEBUGF(infof(data, "Data returned for PAUSED stream %x\n",
                   stream->stream_id));
    }
    else
      data->state.drain = 0; /* this stream is hereby drained */

    return retlen;
  }
  /* If stream is closed, return 0 to signal the http routine to close
     the connection */
  if(stream->closed) {
    return http2_handle_stream_close(httpc, data, stream, err);
  }
  *err = CURLE_AGAIN;
  DEBUGF(infof(data, "http2_recv returns AGAIN for stream %x\n",
               stream->stream_id));
  return -1;
}

/* Index where :authority header field will appear in request header
   field list. */
#define AUTHORITY_DST_IDX 3

/* return number of received (decrypted) bytes */
static ssize_t http2_send(struct connectdata *conn, int sockindex,
                          const void *mem, size_t len, CURLcode *err)
{
  /*
   * BIG TODO: Currently, we send request in this function, but this
   * function is also used to send request body. It would be nice to
   * add dedicated function for request.
   */
  int rv;
  struct http_conn *httpc = &conn->proto.httpc;
  struct HTTP *stream = conn->data->req.protop;
  nghttp2_nv *nva;
  size_t nheader;
  size_t i;
  size_t authority_idx;
  char *hdbuf = (char*)mem;
  char *end;
  nghttp2_data_provider data_prd;
  int32_t stream_id;
  nghttp2_session *h2 = httpc->h2;

  (void)sockindex;

  DEBUGF(infof(conn->data, "http2_send len=%zu\n", len));

  if(stream->stream_id != -1) {
    /* If stream_id != -1, we have dispatched request HEADERS, and now
       are going to send or sending request body in DATA frame */
    httpc->upload_mem = mem;
    httpc->upload_len = len;
    nghttp2_session_resume_data(h2, stream->stream_id);
    rv = nghttp2_session_send(h2);
    if(nghttp2_is_fatal(rv)) {
      *err = CURLE_SEND_ERROR;
      return -1;
    }
    return len - httpc->upload_len;
  }

  /* Calculate number of headers contained in [mem, mem + len) */
  /* Here, we assume the curl http code generate *correct* HTTP header
     field block */
  nheader = 0;
  for(i = 0; i < len; ++i) {
    if(hdbuf[i] == 0x0a) {
      ++nheader;
    }
  }
  /* We counted additional 2 \n in the first and last line. We need 3
     new headers: :method, :path and :scheme. Therefore we need one
     more space. */
  nheader += 1;
  nva = malloc(sizeof(nghttp2_nv) * nheader);
  if(nva == NULL) {
    *err = CURLE_OUT_OF_MEMORY;
    return -1;
  }
  /* Extract :method, :path from request line */
  end = strchr(hdbuf, ' ');
  nva[0].name = (unsigned char *)":method";
  nva[0].namelen = (uint16_t)strlen((char *)nva[0].name);
  nva[0].value = (unsigned char *)hdbuf;
  nva[0].valuelen = (uint16_t)(end - hdbuf);
  nva[0].flags = NGHTTP2_NV_FLAG_NONE;

  hdbuf = end + 1;

  end = strchr(hdbuf, ' ');
  nva[1].name = (unsigned char *)":path";
  nva[1].namelen = (uint16_t)strlen((char *)nva[1].name);
  nva[1].value = (unsigned char *)hdbuf;
  nva[1].valuelen = (uint16_t)(end - hdbuf);
  nva[1].flags = NGHTTP2_NV_FLAG_NONE;

  nva[2].name = (unsigned char *)":scheme";
  nva[2].namelen = (uint16_t)strlen((char *)nva[2].name);
  if(conn->handler->flags & PROTOPT_SSL)
    nva[2].value = (unsigned char *)"https";
  else
    nva[2].value = (unsigned char *)"http";
  nva[2].valuelen = (uint16_t)strlen((char *)nva[2].value);
  nva[2].flags = NGHTTP2_NV_FLAG_NONE;

  hdbuf = strchr(hdbuf, 0x0a);
  ++hdbuf;

  authority_idx = 0;

  for(i = 3; i < nheader; ++i) {
    end = strchr(hdbuf, ':');
    assert(end);
    if(end - hdbuf == 4 && Curl_raw_nequal("host", hdbuf, 4)) {
      authority_idx = i;
      nva[i].name = (unsigned char *)":authority";
      nva[i].namelen = (uint16_t)strlen((char *)nva[i].name);
    }
    else {
      nva[i].name = (unsigned char *)hdbuf;
      nva[i].namelen = (uint16_t)(end - hdbuf);
    }
    hdbuf = end + 1;
    for(; *hdbuf == ' '; ++hdbuf);
    end = strchr(hdbuf, 0x0d);
    assert(end);
    nva[i].value = (unsigned char *)hdbuf;
    nva[i].valuelen = (uint16_t)(end - hdbuf);
    nva[i].flags = NGHTTP2_NV_FLAG_NONE;

    hdbuf = end + 2;
    /* Inspect Content-Length header field and retrieve the request
       entity length so that we can set END_STREAM to the last DATA
       frame. */
    if(nva[i].namelen == 14 &&
       Curl_raw_nequal("content-length", (char*)nva[i].name, 14)) {
      size_t j;
      for(j = 0; j < nva[i].valuelen; ++j) {
        httpc->upload_left *= 10;
        httpc->upload_left += nva[i].value[j] - '0';
      }
      DEBUGF(infof(conn->data,
                   "request content-length=%zu\n", httpc->upload_left));
    }
  }

  /* :authority must come before non-pseudo header fields */
  if(authority_idx != 0 && authority_idx != AUTHORITY_DST_IDX) {
    nghttp2_nv authority = nva[authority_idx];
    for(i = authority_idx; i > AUTHORITY_DST_IDX; --i) {
      nva[i] = nva[i - 1];
    }
    nva[i] = authority;
  }

  switch(conn->data->set.httpreq) {
  case HTTPREQ_POST:
  case HTTPREQ_POST_FORM:
  case HTTPREQ_PUT:
    data_prd.read_callback = data_source_read_callback;
    data_prd.source.ptr = NULL;
    stream_id = nghttp2_submit_request(h2, NULL, nva, nheader,
                                       &data_prd, NULL);
    break;
  default:
    stream_id = nghttp2_submit_request(h2, NULL, nva, nheader,
                                       NULL, NULL);
  }

  free(nva);

  if(stream_id < 0) {
    DEBUGF(infof(conn->data, "http2_send() send error\n"));
    *err = CURLE_SEND_ERROR;
    return -1;
  }

  infof(conn->data, "Using Stream ID: %x (easy handle %p)\n",
        stream_id, conn->data);
  stream->stream_id = stream_id;

  /* put the SessionHandle in the hash with the stream_id as key */
  if(!Curl_hash_add(&httpc->streamsh, &stream->stream_id, sizeof(stream_id),
                    conn->data)) {
    failf(conn->data, "Couldn't add stream to hash!");
    *err = CURLE_OUT_OF_MEMORY;
    return -1;
  }

  rv = nghttp2_session_send(h2);

  if(rv != 0) {
    *err = CURLE_SEND_ERROR;
    return -1;
  }

  if(stream->stream_id != -1) {
    /* If whole HEADERS frame was sent off to the underlying socket,
       the nghttp2 library calls data_source_read_callback. But only
       it found that no data available, so it deferred the DATA
       transmission. Which means that nghttp2_session_want_write()
       returns 0 on http2_perform_getsock(), which results that no
       writable socket check is performed. To workaround this, we
       issue nghttp2_session_resume_data() here to bring back DATA
       transmission from deferred state. */
    nghttp2_session_resume_data(h2, stream->stream_id);
  }

  return len;
}

CURLcode Curl_http2_setup(struct connectdata *conn)
{
  CURLcode result;
  struct http_conn *httpc = &conn->proto.httpc;
  struct HTTP *stream = conn->data->req.protop;

  stream->stream_id = -1;

  if(!stream->header_recvbuf)
    stream->header_recvbuf = Curl_add_buffer_init();

  if((conn->handler == &Curl_handler_http2_ssl) ||
     (conn->handler == &Curl_handler_http2))
    return CURLE_OK; /* already done */

  if(conn->handler->flags & PROTOPT_SSL)
    conn->handler = &Curl_handler_http2_ssl;
  else
    conn->handler = &Curl_handler_http2;

  result = Curl_http2_init(conn);
  if(result)
    return result;

  infof(conn->data, "Using HTTP2, server supports multi-use\n");
  httpc->upload_left = 0;
  httpc->upload_mem = NULL;
  httpc->upload_len = 0;

  httpc->inbuflen = 0;
  httpc->nread_inbuf = 0;

  httpc->pause_stream_id = 0;

  conn->bits.multiplex = TRUE; /* at least potentially multiplexed */
  conn->httpversion = 20;
  conn->bundle->multiuse = BUNDLE_MULTIPLEX;

  infof(conn->data, "Connection state changed (HTTP/2 confirmed)\n");
  Curl_multi_connchanged(conn->data->multi);

  return CURLE_OK;
}

CURLcode Curl_http2_switched(struct connectdata *conn,
                             const char *mem, size_t nread)
{
  CURLcode result;
  struct http_conn *httpc = &conn->proto.httpc;
  int rv;
  struct SessionHandle *data = conn->data;
  struct HTTP *stream = conn->data->req.protop;

  result = Curl_http2_setup(conn);
  if(result)
    return result;

  httpc->recv_underlying = (recving)conn->recv[FIRSTSOCKET];
  httpc->send_underlying = (sending)conn->send[FIRSTSOCKET];
  conn->recv[FIRSTSOCKET] = http2_recv;
  conn->send[FIRSTSOCKET] = http2_send;

  rv = (int) ((Curl_send*)httpc->send_underlying)
    (conn, FIRSTSOCKET,
     NGHTTP2_CLIENT_CONNECTION_PREFACE,
     NGHTTP2_CLIENT_CONNECTION_PREFACE_LEN,
     &result);
  if(result)
    /* TODO: This may get CURLE_AGAIN */
    return result;

  if(rv != 24) {
    failf(data, "Only sent partial HTTP2 packet");
    return CURLE_SEND_ERROR;
  }

  if(conn->data->req.upgr101 == UPGR101_RECEIVED) {
    /* stream 1 is opened implicitly on upgrade */
    stream->stream_id = 1;
    /* queue SETTINGS frame (again) */
    rv = nghttp2_session_upgrade(httpc->h2, httpc->binsettings,
                                 httpc->binlen, NULL);
    if(rv != 0) {
      failf(data, "nghttp2_session_upgrade() failed: %s(%d)",
            nghttp2_strerror(rv), rv);
      return CURLE_HTTP2;
    }
  }
  else {
    /* stream ID is unknown at this point */
    stream->stream_id = -1;
    rv = nghttp2_submit_settings(httpc->h2, NGHTTP2_FLAG_NONE, NULL, 0);
    if(rv != 0) {
      failf(data, "nghttp2_submit_settings() failed: %s(%d)",
            nghttp2_strerror(rv), rv);
      return CURLE_HTTP2;
    }
  }

  rv = (int)nghttp2_session_mem_recv(httpc->h2, (const uint8_t*)mem, nread);

  if(rv != (int)nread) {
    failf(data, "nghttp2_session_mem_recv() failed: %s(%d)",
          nghttp2_strerror(rv), rv);
    return CURLE_HTTP2;
  }

  /* Try to send some frames since we may read SETTINGS already. */
  rv = nghttp2_session_send(httpc->h2);

  if(rv != 0) {
    failf(data, "nghttp2_session_send() failed: %s(%d)",
          nghttp2_strerror(rv), rv);
    return CURLE_HTTP2;
  }

  return CURLE_OK;
}

#endif