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https://libwebsockets.org/repo/libwebsockets
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212 lines
9.5 KiB
Markdown
212 lines
9.5 KiB
Markdown
# Pico binance via SSPC / serial transport Example
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This is a project for an RPi pico, a cheap, widely available US$4 networkless
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133MHz Cortex M0 embedded SBC.
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It is designed to run Serialized Secure Streams in a transport mux over
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a UART running at 2Mbps, and demo two streams concurrently.
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## Traffic on the UART link
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The UART link has a lws_transport_mux layer that detects link up and down, and
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above that Serialized SS travels in each mux channel.
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1) Mux framing PING / PONG / PONGACK / link detect, channel open / close etc
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2) SS to Binance compressed wss server
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The pico runs the generic lws SS binance client and from around 30 messages a
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second, reports the average price of bitcoin in realtime once a second,
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same as it does if you run it on a PC and using the same SS code.
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3) Every 5s another SS does a GET from https://warmcat.com/index.html to
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demonstrate multiple SS muxing over the UART.
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That involves compressed wss and h2, but the pico has:
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- no network stack (TCP/IP)
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- no tls
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- no h2
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- no wss protocol library
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- no wss compression extension
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The pico creates a generic SS using the same code as the other examples, the
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compressed wss connection is actually fulfilled by the proxy part (lws-minimal-
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secure-streams-custom-proxy-transport) connected over the UART. It passes
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the bursty 20 - 120 KBytes/sec SS payloads over the UART where the binance
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SS client consumes them as if it was all happening on the pico.
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## Hookup
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The three pins shown above need connecting to an FTDI-based
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3.3V UART - USB adapter.
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FTDI is needed because we will run the link at 2Mbps, most cheaper adapters
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don't support this baud rate.
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For this demo 2Mbps is required, since the websocket data from binance is very
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bursty, we have to be able to clear a burst before the next one in order to
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keep up.
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## Build
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This builds as a toplevel project using the pcio sdk, it builds
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lws via a symlink, and links with libwebsockets.a built with `-DLWS_ONLY_SSPC`
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Adapt `PICO_SDK_PATH` below to where your pico sdk is installed
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```
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$ cmake .. -DPICO_SDK_PATH=/projects/pico-sdk
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$ make
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```
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You flash the pico by holding down the button and inserting USB, it mounts as a
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USB storage device. Copy `pico-sspc-binance.uf2` to the storage device and
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unmount it.
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## Running
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On the PC, you need to build `lws-minimal-ssproxy-custom-transport-uart`, from
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`./minimal-examples/ssproxy/ssproxy-custom-transport-uart`,
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which needs lws built with `-DLWS_WITHOUT_EXTENSIONS=0`. This connects to
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`/dev/ttyUSB0` and starts the mux + SS Proxy.
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On the Pico, you can monitor the serial console over USB to see logs via
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`/dev/ttyACM0`, it's a bit awkward since that is created during Pico boot, so
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you miss the earliest logs, but the app on the Pico won't do anything
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interesting until it connects via the proxy, and shows periodic pings on the
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mux layer until then.
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Wait for peer (1Hz pings at mux layer)
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```
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11010626: lws_transport_mux_retry_connect
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11010856: lws_transport_path_client_dump: lws_transport_mux_retry_connect: MUX: 2000AC80, IN: ops=txp_inside_sspc, priv=2000AD80, ONW: ops=txpmuxc, priv=00000000
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11011109: lws_transport_mux_retry_connect: transport not operational
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12004542: sul_ping_cb: issuing ping
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12004802: lws_transport_path_client_dump: cpath: MUX: 00000000, IN: ops=txpmuxc, priv=2000AC80 (IsTM), ONW: ops=txpserial, priv=00000000
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12005055: txp_serial_write: writing 9
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12005287: 0000: F6 00 00 00 00 00 B7 2D 54 .......-T
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12005441:
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12011287: lws_sspc_sul_retry_cb
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12011438: lws_transport_mux_retry_connect
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12011692: lws_transport_path_client_dump: lws_transport_mux_retry_connect: MUX: 2000AC80, IN: ops=txp_inside_sspc, priv=2000AD80, ONW: ops=txpmuxc, priv=00000000
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12011935: lws_transport_mux_retry_connect: transport not operational
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13012121: lws_sspc_sul_retry_cb
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13012256: lws_transport_mux_retry_connect
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13012492: lws_transport_path_client_dump: lws_transport_mux_retry_connect: MUX: 2000AC80, IN: ops=txp_inside_sspc, priv=2000AD80, ONW: ops=txpmuxc, priv=00000000
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13012796: lws_transport_mux_retry_connect: transport not operational
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```
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Get mux layer `PING` from proxy / mux side, return PONG
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```
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13941468: lws_transport_mux_rx_parse: got PING
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13941779: lws_transport_path_client_dump: cpath: MUX: 00000000, IN: ops=txpmuxc, priv=2000AC80 (IsTM), ONW: ops=txpserial, priv=00000000
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13942054: txp_serial_write: writing 17
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13942323: 0000: F7 00 00 00 00 00 00 00 00 00 00 00 00 00 D4 BB ................
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13942578: 0010: 98 .
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13942738:
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```
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Get mux later `PONGACK` (three way PING) response, both sides are up at mux layer.
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This also provides the peer with the proxy device's time in us resolution.
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```
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13955788: lws_transport_mux_rx_parse: got PONGACK: ustime 1630898701380539
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13956011: lws_transport_set_link: ******* transport mux link is UP
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```
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Retry the SS link to proxy at SSS layer, first request open mux channel
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```
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14012976: lws_sspc_sul_retry_cb
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14013133: lws_transport_mux_retry_connect
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14013356: lws_transport_path_client_dump: lws_transport_mux_retry_connect: MUX: 2000AC80, IN: ops=txp_inside_sspc, priv=2000AD80, ONW: ops=txpmuxc, priv=00000000
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14013723: lws_transport_mux_retry_connect: added channel
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14014026: lws_transport_path_client_dump: cpath: MUX: 00000000, IN: ops=txpmuxc, priv=2000AC80 (IsTM), ONW: ops=txpserial, priv=00000000
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14014286: txp_serial_write: writing 2
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14014471: 0000: F0 FF ..
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14014702:
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```
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Receive mux channel open ACK, mux channel ready on both sides, start to issue
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Serialized Secure Streams in it: request binance SS stream
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```
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14019481: lws_transport_mux_rx_parse: ch 255 fully open
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14019661: 0
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14019880: lws_sspc_txp_tx: LPCSCLI_SENDING_INITIAL_TX
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14020118: lws_transport_mux_write: 19
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14020280: txp_serial_write: writing 23
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14020553: 0000: F5 FF 00 13 AA 00 10 01 FF FF FF FF 1D CD 65 00 ..............e.
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14020838: 0010: 62 69 6E 61 6E 63 65 binance
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14020995:
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14037838: (unset) -> LWSSSCS_CREATING
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```
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SS states move forward as proxy fulfils the onward connection, then starts to
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receive SSS payloads (previously compressed wss message payloads) and report
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summaries at 1Hz
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```
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15090846: LWSSSCS_CREATING -> LWSSSCS_CONNECTING
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15091150: LWSSSCS_CONNECTING -> LWSSSCS_CONNECTED
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16091462: sul_hz_cb: price: min: 5170001¢, max: 5170867¢, avg: 5170245¢, (26 prices/s)
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16091795: sul_hz_cb: elatency: min: 137ms, max: 296ms, avg: 203ms, (26 msg/s, 49 KiBytes/s SS RX)
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17091455: sul_hz_cb: price: min: 5169104¢, max: 5170101¢, avg: 5169602¢, (33 prices/s)
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17091746: sul_hz_cb: elatency: min: 139ms, max: 304ms, avg: 173ms, (33 msg/s, 94 KiBytes/s SS RX)
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18091450: sul_hz_cb: price: min: 5169104¢, max: 5171400¢, avg: 5169304¢, (30 prices/s)
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18091749: sul_hz_cb: elatency: min: 134ms, max: 167ms, avg: 139ms, (30 msg/s, 31 KiBytes/s SS RX)
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19091460: sul_hz_cb: price: min: 5169183¢, max: 5169370¢, avg: 5169204¢, (29 prices/s)
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19091753: sul_hz_cb: elatency: min: 136ms, max: 152ms, avg: 139ms, (29 msg/s, 31 KiBytes/s SS RX)
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20091468: sul_hz_cb: price: min: 5169183¢, max: 5171063¢, avg: 5169664¢, (29 prices/s)
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20091791: sul_hz_cb: elatency: min: 136ms, max: 151ms, avg: 139ms, (29 msg/s, 30 KiBytes/s SS RX)
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21091482: sul_hz_cb: price: min: 5169183¢, max: 5171574¢, avg: 5169377¢, (30 prices/s)
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21091759: sul_hz_cb: elatency: min: 136ms, max: 151ms, avg: 139ms, (30 msg/s, 44 KiBytes/s SS RX)
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22091477: sul_hz_cb: price: min: 5168614¢, max: 5170771¢, avg: 5169225¢, (30 prices/s)
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22091772: sul_hz_cb: elatency: min: 135ms, max: 148ms, avg: 139ms, (30 msg/s, 54 KiBytes/s SS RX)
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23091491: sul_hz_cb: price: min: 5169058¢, max: 5169276¢, avg: 5169122¢, (28 prices/s)
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23091772: sul_hz_cb: elatency: min: 136ms, max: 144ms, avg: 138ms, (28 msg/s, 22 KiBytes/s SS RX)
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...
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```
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The periodic second SS reads from https://warmcat.com look like this (it dumps the first and
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last 16 bytes of the rx packet)
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```
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42214221: lws_sspc_deserialize_parse: [mintest-lws|1]: : CONNECTED mintest-lws
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42214520: lws_ss_serialize_state_transition: [mintest-lws|1]: : LPCSCLI_LOCAL_CONNECTED -> LPCSCLI_OPERATIONAL
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42214849: lws_ss_check_next_state_sspc: [mintest-lws|1]: : LWSSSCS_CONNECTING -> LWSSSCS_CONNECTED
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42215248: get_state: [mintest-lws|1]: : LWSSSCS_CONNECTED (5), ord 0x0
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42220399: get_rx: [mintest-lws|1]: : RX 1520, flags 0x1
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42220862: : 0000: 3C 21 44 4F 43 54 59 50 45 20 68 74 6D 6C 3E 0A <!DOCTYPE html>.
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42221074: :
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42221370: : 0000: 3C 6C 69 3E 38 30 20 6D 69 6E 69 6D 61 6C 20 65 <li>80 minimal e
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42221580: :
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42305323: get_rx: [mintest-lws|1]: : RX 1520, flags 0x0
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42305900: : 0000: 78 61 6D 70 6C 65 73 3A 20 3C 61 20 68 72 65 66 xamples: <a href
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42306152: :
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42306411: : 0000: AD 98 3C 2F 74 64 3E 3C 74 64 20 63 6C 61 73 73 ..</td><td class
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42306717: :
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42343404: get_rx: [mintest-lws|1]: : RX 1520, flags 0x0
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42343967: : 0000: 3D 22 67 22 3E E2 AD 98 3C 2F 74 64 3E 3C 2F 74 ="g">...</td></t
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42344184: :
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42344412: : 0000: 77 65 62 73 6F 63 6B 65 74 73 2F 74 72 65 65 2F websockets/tree/
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42344618: :
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42486791: get_rx: [mintest-lws|1]: : RX 1520, flags 0x0
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42487366: : 0000: 6C 69 62 2F 65 76 65 6E 74 2D 6C 69 62 73 22 20 lib/event-libs"
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42487635: :
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42487894: : 0000: 31 36 20 69 62 22 3E 0A 20 20 20 20 20 3C 68 31 16 ib">. <h1
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42488113: :
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42527399: get_rx: [mintest-lws|1]: : RX 1277, flags 0x0
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42527903: : 0000: 3E 51 41 3C 2F 68 31 3E 0A 20 20 20 20 20 20 4C >QA</h1>. L
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42528116: :
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42528404: : 0000: 3C 2F 62 6F 64 79 3E 0A 3C 2F 68 74 6D 6C 3E 0A </body>.</html>.
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42528637: :
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42570288: get_rx: [mintest-lws|1]: : RX 0, flags 0x2
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```
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