nghttp2 多部分 POST 消息

Question

我目前正在尝试使用 nghttp2 构建多部分消息。该消息应按以下结构。

我应该使用 nghttp2_submit_request(here) 函数，nva 作为我的 HTTP/2 header，nghttp2_data_provider *data_prd 作为我的数据。但是，我仍然不明白如何创建两条消息（两条消息 headers）。

更新：

我可以在我的源代码中描述我的想法吗？请看下面。在这里，我使用 nghttp2_data_provider 打开一个音频文件，并写入缓冲区。

ssize_t data_prd_read_callback(
    nghttp2_session *session, int32_t stream_id, uint8_t *buf, size_t length,
    uint32_t *data_flags, nghttp2_data_source *source, void *user_data) 
{

  printf("[INFO] C ----------------------------> S (DATA post body), length:%zu\n", length);

  int fd = source->fd;
  ssize_t r;
// writting my opened audio file into buffer
  while ((r = read(fd, buf, length)) == -1 && errno == EINTR); 
  printf("stream_id:%d, nread:%zu\r\n", stream_id, r);
  return nread;
}



void submit_postAudio(http2_session_data *session_data) {
  int32_t stream_id;
  http2_stream_data *stream_data = session_data->stream_data[STREAM_ID_REQUESTAUDIO];
  const char *uri = stream_data->uri;
  const struct http_parser_url *u = stream_data->u;
  char byLength = 0;

  const nghttp2_nv hdrs[] = {
  MAKE_NV(":method", "POST"),   MAKE_NV_CS(":path", stream_data->path),
  MAKE_NV(":scheme", "https"), MAKE_NV("accept", "*/*"),    
  MAKE_NV_CS("authorization", stream_data->access_token),
  MAKE_NV("content-type", "multipart/form-data; boundary=abcdefg123")
  };

  fprintf(stderr, "Request headers:\n");
  print_headers(stderr, hdrs, ARRLEN(hdrs));

  int fileDescriptor = open ("/my_audio.wmv", O_APPEND);  // open my audio file 
  nghttp2_data_provider data_prd;
  data_prd.source.fd = fileDescriptor   // set the file descriptor 
  data_prd.source.ptr = NULL;
  data_prd.read_callback = data_prd_read_callback;

  stream_id = nghttp2_submit_request(session_data->session, NULL, hdrs,
                                     ARRLEN(hdrs), &data_prd, stream_data);
  if (stream_id < 0) {
    errx(1, "Could not submit HTTP request: %s", nghttp2_strerror(stream_id));
  }

  stream_data->stream_id = stream_id;
}

让我困惑的是 1) 如何向音频添加 header（更具体地说是消息 header）。 2) 如何在 Json 文件后附加它。

Answer 1

一个multi-part mime header通常是这样定义的：

-----boundary_id
name: value  # header stuff here, ie. "name: value" per line. No spaces in name, all ASCII
CRLF         # End of header is defined with an extra linefeed, AKA a "null line", see ref 1.

content here, ends at next boundary id

-----boundary_id

Ref 1

如果内容是二进制的，你会 usually encode it as base-64 有一个固定的行长度（你 也可以 发送二进制数据，但必须采取额外的预防措施 white-spaces 例如最后的 line-feed)。 header field-name 说明可以包括在内：

Content-Transfer-Encoding: Base64

（二进制数据使用值“binary”代替）。

边界 ID 必须足够唯一，以免成为任何其他内容的一部分。它在主 header 中定义时不使用 double-dashes，但你需要在它作为分隔符的任何地方添加这样的 double-dashes。

所以在这种情况下，整个消息看起来像这样：

name1: value1
name2: value2
name3: value3
x-comment: "as required by the specs (ignore this line)"
content-type: multipart/form-data; boundary: my_unique_boundary_id

--my_unique_boundary_id
Content-Disposition: form-data; name="metadata"
Content-Type: application/json; charset=UTF-08

{JSON data here}

--my_unique_boundary_id
Content-Disposition: form-data; name="audio"
Content-Type: application/octet-stream
Content-Transfer-Encoding: Base64
x-comment: "binary audio encoded as base-64 follows next"
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... etc.

--my_unique_boundary_id

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