Function hpack_encode_header_block

src/proxy/http2/HPACK.cc:768–837

}

int64_t
hpack_encode_header_block(HpackIndexingTable &indexing_table, uint8_t *out_buf, const size_t out_buf_len, HTTPHdr *hdr,
                          int32_t maximum_table_size)
{
  uint8_t             *cursor      = out_buf;
  const uint8_t *const out_buf_end = out_buf + out_buf_len;

  ink_assert(http_hdr_type_get(hdr->m_http) != HTTP_TYPE_UNKNOWN);

  // Update dynamic table size
  if (maximum_table_size >= 0) {
    indexing_table.update_maximum_size(maximum_table_size);
    int64_t written = encode_dynamic_table_size_update(cursor, out_buf_end, maximum_table_size);
    if (written == HPACK_ERROR_COMPRESSION_ERROR) {
      return HPACK_ERROR_COMPRESSION_ERROR;
    }
    cursor += written;
  }

  for (auto &field : *hdr) {
    // Convert field name to lower case to follow HTTP2 spec
    // This conversion is needed because WKSs in MIMEFields is old fashioned
    std::string_view      original_name = field.name_get();
    int                   name_len      = original_name.size();
    ts::LocalBuffer<char> local_buffer(name_len);
    char                 *lower_name = local_buffer.data();
    for (int i = 0; i < name_len; i++) {
      lower_name[i] = ParseRules::ink_tolower(original_name[i]);
    }

    std::string_view name{lower_name, static_cast<size_t>(name_len)};
    std::string_view value = field.value_get();

    // Choose field representation (See RFC7541 7.1.3)
    // - Authorization header obviously should not be indexed
    // - Short Cookie header should not be indexed because of low entropy
    HpackField field_type;
    if ((value.size() < 20 && match(name.data(), name.length(), HPACK_HDR_FIELD_COOKIE.data(), HPACK_HDR_FIELD_COOKIE.length())) ||
        match(name.data(), name.length(), HPACK_HDR_FIELD_AUTHORIZATION.data(), HPACK_HDR_FIELD_AUTHORIZATION.length())) {
      field_type = HpackField::NEVERINDEX_LITERAL;
    } else {
      field_type = HpackField::INDEXED_LITERAL;
    }

    HpackHeaderField        header{name, value};
    const HpackLookupResult result = indexing_table.lookup(header);

    int64_t written = 0;
    switch (result.match_type) {
    case HpackMatch::NONE:
      written = encode_literal_header_field_with_new_name(cursor, out_buf_end, header, indexing_table, field_type);
      break;
    case HpackMatch::NAME:
      written =
        encode_literal_header_field_with_indexed_name(cursor, out_buf_end, header, result.index, indexing_table, field_type);
      break;
    case HpackMatch::EXACT:
      written = encode_indexed_header_field(cursor, out_buf_end, result.index);