1RX depacketizer 2=============== 3 4This component takes a QUIC packet and parses the frames contained therein, 5to be forwarded to appropriate other components for further processing. 6 7In the [overview], this is called the "RX Frame Handler". The name "RX 8depacketizer" was chosen to reflect the kinship with the [TX packetizer]. 9 10Main structures 11--------------- 12 13### Connection 14 15Represented by an `QUIC_CONNECTION` object, defined in 16[`include/internal/quic_ssl.h`](../../../include/internal/quic_ssl.h). 17 18### Stream 19 20Represented by an `QUIC_STREAM` object (yet to be defined). 21 22### Packets 23 24Represented by the `OSSL_QRX_PKT` structure, defined in 25`include/internal/quic_record_rx.h` in [QUIC Demuxer and Record Layer (RX+TX)]. 26 27Interactions 28------------ 29 30The RX depacketizer receives a packet from the QUIC Read Record Layer, and 31then processes frames in two phases: 32 331. [Collect information for the ACK Manager](#collect-information-for-the-ack-manager) 342. [Pass frame data](#pass-frame-data) 35 36### Other components 37 38There are a number of other components that the RX depacketizer wants to 39interact with: 40 41- [ACK manager] 42- Handshake manager, which is currently unspecified. It's assumed that 43 this will wrap around what is called the "TLS Handshake Record Layer", 44 in the [overview] 45- Session manager, which is currently unspecified for QUIC, but may very 46 well be the existing `SSL_SESSION` functionality, extended to fit QUIC 47 purposes. 48- Flow control, which is currently unspecified. In the [overview], it's 49 called the "Flow Controller And Statistics Collector" 50- Connection manager, which is currently unspecified. In the [overview], 51 there's a "Connection State Machine" that the "RX Frame Handler" isn't 52 talking directly with, so it's possible that the Connection manager will 53 turn out to be the Handshake manager. 54- Stream SSL objects, to pass the stream data to. 55 56### Read and process a packet 57 58Following how things are designed elsewhere, the depacketizer is assumed to 59be called "from above" using the following function: 60 61``` C 62__owur int ossl_quic_depacketize(QUIC_CONNECTION *connection); 63``` 64 65This function would create an `OSSL_QRX_PKT` and call the QUIC Read Record 66Layer with a pointer to it, leaving it to the QUIC Read Record Layer to fill 67in the data. 68 69This uses the `ossl_qrx_read_pkt()` packet reading function from 70[QUIC Demuxer and Record Layer (RX+TX)]. 71(the `OSSL_QRX_PKT` structure / sub-structure needs to be extended to take 72an `OSSL_TIME`, possibly by reference, which should be filled in with the 73packet reception time) 74 75### Collect information for the [ACK manager] 76 77This collects appropriate data into a `QUIC_ACKM_RX_PKT` structure: 78 79- The packet number (`packet->packet_number`) 80- The packet receive time (`received`) 81- The packet space, which is always: 82 - `QUIC_PN_SPACE_INITIAL` when `packet->packet_type == pkt_initial` 83 - `QUIC_PN_SPACE_HANDSHAKE` when `packet->packet_type == pkt_handshake` 84 - `QUIC_PN_SPACE_APP` for all other packet types 85- The ACK eliciting flag. This is calculated by looping through all 86 frames and noting those that are ACK eliciting, as determined from 87 [Table 1](#table-1) below) 88 89### Passing frame data 90 91This loops through all the frames, extracts data where there is any 92and calls diverse other components as shown in the Passed to column in 93[Table 1](#table-1) below. 94 95#### Table 1 96 97Taken from [RFC 9000 12.4 Frames and Frame Types] 98 99| Type | Name | Passed to | ACK eliciting | I | H | 0 | 1 | 100|------|-------------------------|--------------------------|---------------|----------|----------|----------|----------| 101| 0x00 | [padding] | - | | ✔ | ✔ | ✔ | ✔ | 102| 0x01 | [ping] | - | ✔ | ✔ | ✔ | ✔ | ✔ | 103| 0x02 | [ack 0x02] | [ACK manager] [^1] | | ✔ | ✔ | | ✔ | 104| 0x03 | [ack 0x03] | [ACK manager] [^1] | | ✔ | ✔ | | ✔ | 105| 0x04 | [reset_stream] | - [^2] | ✔ | | | ✔ | ✔ | 106| 0x05 | [stop_sending] | - [^3] | ✔ | | | ✔ | ✔ | 107| 0x06 | [crypto] | Handshake manager | ✔ | ✔ | ✔ | | ✔ | 108| 0x07 | [new_token] | Session manager | ✔ | | | | ✔ | 109| 0x08 | [stream 0x08] | Apprioriate stream [^4] | ✔ | | | ✔ | ✔ | 110| 0x09 | [stream 0x09] | Apprioriate stream [^4] | ✔ | | | ✔ | ✔ | 111| 0x0A | [stream 0x0A] | Apprioriate stream [^4] | ✔ | | | ✔ | ✔ | 112| 0x0B | [stream 0x0B] | Apprioriate stream [^4] | ✔ | | | ✔ | ✔ | 113| 0x0C | [stream 0x0C] | Apprioriate stream [^4] | ✔ | | | ✔ | ✔ | 114| 0x0D | [stream 0x0D] | Apprioriate stream [^4] | ✔ | | | ✔ | ✔ | 115| 0x0E | [stream 0x0E] | Apprioriate stream [^4] | ✔ | | | ✔ | ✔ | 116| 0x0F | [stream 0x0F] | Apprioriate stream [^4] | ✔ | | | ✔ | ✔ | 117| 0x10 | [max_data] | Flow control [^5] | ✔ | | | ✔ | ✔ | 118| 0x11 | [max_stream_data] | Flow control [^5] | ✔ | | | ✔ | ✔ | 119| 0x12 | [max_streams 0x12] | Connection manager? [^6] | ✔ | | | ✔ | ✔ | 120| 0x13 | [max_streams 0x13] | Connection manager? [^6] | ✔ | | | ✔ | ✔ | 121| 0x14 | [data_blocked] | Flow control [^5] | ✔ | | | ✔ | ✔ | 122| 0x15 | [stream_data_blocked] | Flow control [^5] | ✔ | | | ✔ | ✔ | 123| 0x16 | [streams_blocked 0x16] | Connection manager? [^6] | ✔ | | | ✔ | ✔ | 124| 0x17 | [streams_blocked 0x17] | Connection manager? [^6] | ✔ | | | ✔ | ✔ | 125| 0x18 | [new_connection_id] | Connection manager | ✔ | | | ✔ | ✔ | 126| 0x19 | [retire_connection_id] | Connection manager | ✔ | | | ✔ | ✔ | 127| 0x1A | [path_challenge] | Connection manager? [^7] | ✔ | | | ✔ | ✔ | 128| 0x1B | [path_response] | Connection manager? [^7] | ✔ | | | | ✔ | 129| 0x1C | [connection_close 0x1C] | Connection manager | | ✔ | ✔ | ✔ | ✔ | 130| 0x1D | [connection_close 0x1D] | Connection manager | | | | ✔ | ✔ | 131| 0x1E | [handshake_done] | Handshake manager | ✔ | | | | ✔ | 132| ???? | *[Extension Frames]* | - [^8] | ✔ | | | | | 133 134The I, H, 0, and 1 columns are validity in different packet types, with this meaning: 135 136| Pkts | Description | 137|:----:|----------------------------| 138| I | Valid in Initial packets | 139| H | Valid in Handshake packets | 140| 0 | Valid in 0-RTT packets | 141| 1 | Valid in 1-RTT packets | 142 143Notes: 144 145[^1]: This creates and populates an `QUIC_ACKM_ACK` structure, then calls 146 `QUIC_ACKM_on_rx_ack_frame()`, with the appropriate context 147 (`QUIC_ACKM`, the created `QUIC_ACKM_ACK`, `pkt_space` and `rx_time`) 148[^2]: Immediately terminates the appropriate receiving stream `QUIC_STREAM` 149 object. 150 This includes discarding any buffered application data. 151 For a stream that's send-only, the error `STREAM_STATE_ERROR` is raised, 152 and the `QUIC_CONNECTION` object is terminated. 153[^3]: Immediately terminates the appropriate sending stream `QUIC_STREAM` 154 object. 155 For a stream that's receive-only, the error `STREAM_STATE_ERROR` is 156 raised, and the `QUIC_CONNECTION` object is terminated. 157[^4]: The frame payload (Stream Data) is passed as is to the `QUIC_STREAM` 158 object, along with available metadata (offset and length, as determined 159 to be available from the lower 3 bits of the frame type). 160[^5]: The details of what flow control will need are yet to be determined 161[^6]: I imagine that `max_streams` and `streams_blocked` concern a Connection 162 manager before anything else. 163[^7]: I imagine that path challenge/response concerns a Connection manager 164 before anything else. 165[^8]: We have no idea what extension frames there will be. However, we 166 must at least acknowledge their presence, so much is clear from the RFC. 167 168[overview]: https://github.com/openssl/openssl/blob/master/doc/designs/quic-design/quic-overview.md 169[TX packetizer]: https://github.com/openssl/openssl/pull/18570 170[SSL object refactoring using SSL_CONNECTION object]: https://github.com/openssl/openssl/pull/18612 171[QUIC Demuxer and Record Layer (RX+TX)]: https://github.com/openssl/openssl/pull/18949 172[ACK manager]: https://github.com/openssl/openssl/pull/18564 173[RFC 9000 12.4 Frames and Frame Types]: https://datatracker.ietf.org/doc/html/rfc9000#section-12.4 174[padding]: https://datatracker.ietf.org/doc/html/rfc9000#section-19.1 175[ping]: https://datatracker.ietf.org/doc/html/rfc9000#section-19.2 176[ack 0x02]: https://datatracker.ietf.org/doc/html/rfc9000#section-19.3 177[ack 0x03]: https://datatracker.ietf.org/doc/html/rfc9000#section-19.3 178[reset_stream]: https://datatracker.ietf.org/doc/html/rfc9000#section-19.4 179[stop_sending]: https://datatracker.ietf.org/doc/html/rfc9000#section-19.5 180[crypto]: https://datatracker.ietf.org/doc/html/rfc9000#section-19.6 181[new_token]: https://datatracker.ietf.org/doc/html/rfc9000#section-19.7 182[stream 0x08]: https://datatracker.ietf.org/doc/html/rfc9000#section-19.8 183[stream 0x09]: https://datatracker.ietf.org/doc/html/rfc9000#section-19.8 184[stream 0x0A]: https://datatracker.ietf.org/doc/html/rfc9000#section-19.8 185[stream 0x0B]: https://datatracker.ietf.org/doc/html/rfc9000#section-19.8 186[stream 0x0C]: https://datatracker.ietf.org/doc/html/rfc9000#section-19.8 187[stream 0x0D]: https://datatracker.ietf.org/doc/html/rfc9000#section-19.8 188[stream 0x0E]: https://datatracker.ietf.org/doc/html/rfc9000#section-19.8 189[stream 0x0F]: https://datatracker.ietf.org/doc/html/rfc9000#section-19.8 190[max_data]: https://datatracker.ietf.org/doc/html/rfc9000#section-19.9 191[max_stream_data]: https://datatracker.ietf.org/doc/html/rfc9000#section-19.10 192[max_streams 0x12]: https://datatracker.ietf.org/doc/html/rfc9000#section-19.11 193[max_streams 0x13]: https://datatracker.ietf.org/doc/html/rfc9000#section-19.11 194[data_blocked]: https://datatracker.ietf.org/doc/html/rfc9000#section-19.12 195[stream_data_blocked]: https://datatracker.ietf.org/doc/html/rfc9000#section-19.13 196[streams_blocked 0x16]: https://datatracker.ietf.org/doc/html/rfc9000#section-19.14 197[streams_blocked 0x17]: https://datatracker.ietf.org/doc/html/rfc9000#section-19.14 198[new_connection_id]: https://datatracker.ietf.org/doc/html/rfc9000#section-19.15 199[retire_connection_id]: https://datatracker.ietf.org/doc/html/rfc9000#section-19.16 200[path_challenge]: https://datatracker.ietf.org/doc/html/rfc9000#section-19.17 201[path_response]: https://datatracker.ietf.org/doc/html/rfc9000#section-19.18 202[connection_close 0x1C]: https://datatracker.ietf.org/doc/html/rfc9000#section-19.19 203[connection_close 0x1D]: https://datatracker.ietf.org/doc/html/rfc9000#section-19.19 204[handshake_done]: https://datatracker.ietf.org/doc/html/rfc9000#section-19.20 205[Extension Frames]: https://datatracker.ietf.org/doc/html/rfc9000#section-19.21 206
