Method write_hdr_protocol_stack

src/proxy/http/HttpTransactHeaders.cc:631–683

write the protocol stack to the @a via_string. If @a detailed then do the full stack, otherwise just the "top level" protocol. Returns the number of characters appended to hdr_string (no nul appended).

/// If @a detailed then do the full stack, otherwise just the "top level" protocol.
/// Returns the number of characters appended to hdr_string (no nul appended).
int
HttpTransactHeaders::write_hdr_protocol_stack(char *hdr_string, size_t len, ProtocolStackDetail pSDetail,
                                              std::string_view *proto_buf, int n_proto, char separator)
{
  char *hdr   = hdr_string; // keep original pointer for size computation later.
  char *limit = hdr_string + len;

  if (n_proto <= 0 || hdr == nullptr || len <= 0) {
    // nothing
  } else if (ProtocolStackDetail::Full == pSDetail) {
    for (std::string_view *v = proto_buf, *v_limit = proto_buf + n_proto; v < v_limit && (hdr + v->size() + 1) < limit; ++v) {
      if (v != proto_buf) {
        *hdr++ = separator;
      }
      memcpy(hdr, v->data(), v->size());
      hdr += v->size();
    }
  } else {
    std::string_view *proto_end  = proto_buf + n_proto;
    bool              http_1_0_p = std::find(proto_buf, proto_end, IP_PROTO_TAG_HTTP_1_0) != proto_end;
    bool              http_1_1_p = std::find(proto_buf, proto_end, IP_PROTO_TAG_HTTP_1_1) != proto_end;

    if ((http_1_0_p || http_1_1_p) && hdr + 10 < limit) {
      bool tls_p = std::find_if(proto_buf, proto_end, [](std::string_view tag) { return IsPrefixOf("tls/"sv, tag); }) != proto_end;

      memcpy(hdr, "http", 4);
      hdr += 4;
      if (tls_p) {
        *hdr++ = 's';
      }

      // If detail level is compact (RFC 7239 compliant "proto" value for Forwarded field), stop here.

      if (ProtocolStackDetail::Standard == pSDetail) {
        *hdr++        = '/';
        bool http_2_p = std::find(proto_buf, proto_end, IP_PROTO_TAG_HTTP_2_0) != proto_end;
        bool http_3_p = std::find(proto_buf, proto_end, IP_PROTO_TAG_HTTP_3) != proto_end;
        if (http_2_p) {
          *hdr++ = '2';
        } else if (http_3_p) {
          *hdr++ = '3';
        } else if (http_1_0_p) {
          memcpy(hdr, "1.0", 3);
          hdr += 3;
        } else if (http_1_1_p) {
          memcpy(hdr, "1.1", 3);
          hdr += 3;
        }
      }
    }
  }
  return hdr - hdr_string;
}

///////////////////////////////////////////////////////////////////////////////
// Name       : insert_via_header_in_request