CHANGELOG revision 4947ba95
12019-10-08
2    - 2.4.5
3    - [OPTIMIZATION]: flush encoder stream only when necessary.
4    - [BUGFIX] Use ls-qpack v0.10.2 for new API -- and for a bug fix.
5    - [BUGFIX] Typo in IETF conn SETTINGS writer.
6    - Use latest BoringSSL.
7
82019-10-08
9    - 2.4.4
10    - [API] Add lsquic_alpn2ver() to aid parsing Alt-Svc header.
11    - [BUGFIX] NULL dereference when H3 frame header would be split.
12    - [BUGFIX] Do not close fixed-size H3 frame prematurely.
13    - [BUGFIX] Allow PING frames in IETF mini conn.
14    - [BUGFIX] Mini conns: don't send any packets after receiving
15      CONNECTION_CLOSE.
16    - [BUGFIX] Client migration: reserve slot for DCID from transport params.
17    - [BUGFIX] Allow max_early_data_size=0 -- early_data might not be there.
18    - [BUGFIX] Use an invalid stream number to reset BPT cache (zero is now a
19      valid stream number).
20    - [SPEC] Use FINAL_SIZE_ERROR when FIN mismatch is detected.
21    - [OPTIMIZATION] Closed connection only gets one chance to send packets.
22    - [OPTIMIZATION] Flush headers stream before packetizing stream data.
23    - [OPTIMIZATION] process QPACK encoder STREAM frames immediately.
24    - Update ls-qpack to v0.10.1.
25
262019-09-30
27    - 2.4.3
28    - Add GQUIC versions to the list of h3 ALPNs for Alt-Svc header.
29      For example, h3-Q043.  Chrome will switch to using this format at
30      some point in the future.
31    - [BUGFIX] Send correct value in max_streams_uni transport param
32    - [SPEC] Abort IETF QUIC connection if max_early_data_size is not set
33      to 0xFFFFFFFF
34
352019-09-23
36    - 2.4.2
37    - [BUGFIX] H3 framing: fix zero-byte write when space is available
38    - [BUGFIX] Don't send STREAM frame when incoming unidirectgional stream
39      is closed
40    - [BUGFIX] Cancel all pending writes by stream reset by a GOAWAY
41    - [BUGFIX] Fix use-after-free in IETF full conn
42    - [OPTIMIZATION] Wait for session tickets for two seconds and then drop
43      SSL object and crypto streams.
44
452019-09-18
46    - 2.4.0
47    - [FEATURE] QUIC and HTTP/3 Internet Draft 23 support
48
492019-09-13
50    - 2.3.1
51    - [BUGFIX] Fix memory leaks
52    - [BUGFIX] Fix unit tests
53
542019-09-12
55    - 2.3.0
56    - [FEATURE] BBR congestion control is on by default
57    - [BUGFIX] BBR app-limited logic
58    - [BUGFIX] Fix uninitialized warnings in IETF
59    - [BUGFIX] Update ls-qpack to v0.9.14
60    - [CLEANUP] Code cleanup
61
622019-09-11
63    - 2.2.0
64    - [FEATURE] Server code is included in the library
65    - [FEATURE] IETF QUIC and HTTP/3 Support (ID-22)
66
672019-05-13
68    - 1.21.2
69    - [OPTIMIZATION] HPACK: use history to improve compression performance
70
712019-05-06
72    - 1.21.1
73    - [BUGFIX] If FIN or RST not received, don't delay stream destruction.
74    - [OPTIMIZATION] Speed up HPACK encoder by using same hash value to
75      search static and dynamic tables.
76
772019-04-12
78    - 1.21.0
79    - [FEATURE] Add qlog log module.
80
812019-04-01
82    - 1.20.0
83    - [FEATURE] Add support for Q046.
84
852019-03-19
86    - 1.19.6
87    - [BUGFIX] Ensure that Largest Observed does not decrease in ACKs we
88      send.  ACK frames placed in packets in buffered queues (optimization
89      introduced in 1.17.15) can be preceded by an ACK frame generated later.
90      In this case, the older ACK frame should not be sent out, as Chromium-
91      based servers flags decrease in the ACK frame's Largest Observed value
92      as an error.
93
942019-03-05
95    - 1.19.5
96    - [BUGFIX] Use correct public key from PUBS based on KEXS index.
97    - [BUGFIX] Check flags before dispatching writes, avoiding assert.
98    - [BUGFIX] Set :scheme to "https" (instead of "HTTP").
99
1002019-02-25
101    - 1.19.4
102    - [BUGFIX] Check buffer bounds when looking up version in 0-RTT blob.
103    - [BUGFIX] http_client: don't fetch 0-rtt info if handshake failed.
104    - Log number of pacer calls at DEBUG, rather than NOTICE, level.
105
1062019-02-18
107    - 1.19.3
108    - [BUGFIX] Q044: don't encode packet number in 6 bytes.  Six-byte
109      packet number encoding does not exist in Q044.  This fixes a
110      regression introduced in '[BUGFIX] Buffered packets can contain
111      ACK frames' -- we need to keep QUIC version in mind when selecting
112      the longest possible packet number encoding used for the buffered
113      packet that carries the ACK.
114    - [BUGFIX] Do not increase CWND when timeout occurs.
115    - http_client: support setting handshake timeout on command line.
116      Use -o handshake_to=timeout.
117    - http_client: use -k to connect UDP socket to pick up ICMP errors.
118    - http_client: allow pathless mode, when only handshake is performed
119      without issuing any requests.  This can be done by simply not
120      specifying a -p flag on the command line.
121
1222019-02-11
123    - 1.19.2
124    - [BUGFIX] Begin negotiation with version provided in 0-RTT info.
125    - [BUGFIX] Version checking in zero_rtt deserialize function.
126
1272019-02-04
128    - 1.19.1
129    - [BUGFIX] Fix Windows build.
130
1312019-02-04
132    - 1.19.0
133    - [FEATURE, API Change] 0-RTT support.  Add function to export 0-RTT
134      information; it can be supplied to a subsequent connect() call.
135    - [FEATURE] Add -0 flag to http_client to exercise 0-RTT support.
136    - [BUGFIX] Resuscitate the Windows build.
137    - [BUGFIX] Send HTTP settings (max header list size) if necessary.
138    - [BUGFIX] Buffered packets can contain ACK frames.
139    - [BUGFIX] Make packet writeable once all STREAM frames are elided.
140    - [BUGFIX] Fix potential null dereference when realloc fails.
141    - cmake: simplify build configuration.
142
1432019-01-28
144    - 1.18.0
145    - [API Change] Can specify clock granularity in engine settings.
146    - [BUGFIX] Pacer uses fixed clock granularity.  Since the change on
147      2018-04-09, it is not necessary to try to approximate the next tick
148      time in the pacer: it can use fix clock granularity specified by
149      the user.
150    - [BUGFIX] Do not tick constantly before handshake is done.
151    - [BUGFIX] Do not exit tick prematurely: reuse packet with ACK.  Even
152      if we cannot allocate *more* packets, we could still be able to write
153      to one already allocated.
154    - [BUGFIX] Do not schedule pacer if there are no lost packets.
155
1562019-01-17
157    - 1.17.15
158    - [BUGFIX] http_client: make sure only one read per on_read() callback
159      is performed in the header conversion bypass (-B) mode.
160    - http_client: with -E, assign random priority when stream is created.
161    - [OPTIMIZATION] On immediate write, place an ACK frame into the first
162      buffered packet if an ACK is queued.  This reduces the number of
163      standalone ACK packets.
164    - [OPTIMIZATION] Allow placing more than one STREAM frame from the same
165      stream into an outgoing packet.  This change minimizes the number of
166      buffered packets required to store several small HTTP messages by
167      virtue of allowing more than one STREAM frame from HEADERS stream in
168      the same packet.
169    - [OPTIMIZATION] Flush headers when writing to buffered packets.  This
170      causes the headers to be written to the same buffered packet queue,
171      thereby improving packet utilization, especially for small HTTP
172      messages.
173
1742019-01-16
175    - 1.17.14
176    - [FEATURE] http_client can now collect stats: time to connect, TTFB,
177      time to download, requests per seconds, and bandwidth.  See -t flag.
178    - [BUGFIX] http_client: -B, -K, and -r can be used at the same time.
179    - [BUGFIX] http_client: do not display cert chain before each request.
180      Now this is only done once per connection, if the handshake is
181      successful and -a option is given.
182    - [BUGFIX] Do not wait to dispatch on_close() after reading.  If a
183      stream is scheduled to be closed after on_read() callback returns,
184      close it immediately instead of waiting until the end of the tick.
185      If client creates new request from on_close() event, they will be
186      processed in the same tick instead of waiting for the next one.
187    - [BUGFIX] HEADERS stream is critical: always treat it with highest
188      priority.
189
1902019-01-10
191    - 1.17.12
192    - [FEATURE] http_client can now issue parallel requests in the context
193      of a single connection.  See -w option.
194
1952019-01-03
196    - 1.17.11
197    - Fix strict aliasing warning in optimized compilation.
198
1992018-12-27
200    - 1.17.10
201    - Fix the example program to be able to use parallel connections
202      again.  (See the -n argument.)
203
2042018-12-18
205    - 1.17.9
206    - [BUGFIX] Engine: reduce minimum batch size from 256 to 4
207
2082018-12-10
209    - 1.17.8
210    - [BUGFIX] Fix compilation on FreeBSD and 32-bit Linux
211
2122018-12-03
213    - 1.17.7
214    - [BUGFIX] Do not unset PING alarm before ringing expired alarms.
215      This prevented PING from ever being sent.
216
2172018-11-29
218    - 1.17.6
219    - Add failsafe: resume sending packets after some time
220
221      The change puts a 1-second limit on the amount of time the engine
222      will not send packets after some packets are delayed.  This makes
223      the library robust in case the user does not unblock the engine
224      explicitly using lsquic_engine_send_unsent_packets() call.
225
226    - [BUGFIX] Handle corner cases in send controller when packets are
227      a) delayed or b) dropped during repackaging.
228    - [BUGFIX] Memory leak: destroy buffered packets during controller
229      cleanup.
230
2312018-11-16
232    - 1.17.3
233    - [BUGFIX] Do not send STOP_WAITING frames when using Q044
234
2352018-10-19
236    - 1.17.2
237    - [BUGFIX] Memory leak in test_frame_rw unit test.
238    - [BUGFIX] Parsing packets with short IETF header: do not overwrite
239      flags.  (Only a problem in unit tests -- benign otherwise.)
240
2412018-10-16
242    - 1.17.0
243    - [API Change] Packet out Memory Interface (PMI) update:
244      - Split PMI pool return into pmi_release and pmi_return
245      - PMI callbacks take peer_ctx and is_ipv6 arguments
246    - [BUGFIX] Fix use-after-free when certificate is updated
247    - Silence gcc warning in optimized mode by performing useless
248      initialization
249    - cmake: use the standard variable CMAKE_BUILD_TYPE instead of
250      DEVEL_MODE
251
2522018-10-03
253    - 1.16.0
254    - [API Change] Add lsquic_conn_n_avail_streams()
255    - [BUGFIX] only dispatch crypto stream read events if WANT_READ is on
256
2572018-09-27
258    - 1.15.0
259    - [API Change] Add LSCONN_ST_PEER_GOING_AWAY to the list of conn statuses
260    - [BUGFIX] free uncompressed headers correctly when error occurs
261
2622018-09-12
263    - 1.14.3
264    - [BUGFIX] Do not abort conn on STREAM frame for a reset stream
265    - [BUGFIX] Drop packets that would become empty due to repackaging.
266      Packets on the scheduled queue may be marked for repackaging.
267      Frames such as ACK frame that are never resent are removed from
268      repackaged packets.  We must check that the newly repackaged packet
269      would not be empty.  If it would be, it is destroyed instead and
270      the next packet on the scheduled queue is used.  Note that this
271      change only affects the logic to return the next packet to be sent.
272      Lost packets that are being rescheduled are already processed in
273      this fashion.
274    - Byteswap CID before logging it - this makes it match Chrome CIDs.
275      (Except Q035, which is the last little-endian GQUIC version we
276      support.)
277
2782018-09-06
279    - 1.14.0
280    - [API Change] Disable packet sending if full batch cannot be sent
281      If lsquic_packets_out_f() cannot send the whole batch, disable
282      packet sending until lsquic_engine_send_unsent_packets() is called.
283    - [BUGFIX] Handle case when STREAM frame does not fit.
284    - [BUGFIX] Always allow incoming STREAM frames to overlap.  Peers
285      may send overlapping STREAM frames even if using versions older
286      than Q043.
287    - Custom header set fixes:
288      - set "FIN reached" flag when custom header with FIN flag is
289        claimed;
290      - do not return custom header set for a reset stream.
291
2922018-08-27
293
294    - 1.13.0
295    - [FEATURE, API Change] Add ability to create custom header set
296      objects via callbacks.  This avoids reading and re-parsing
297      headers from the stream.
298
2992018-08-27
300
301    - 1.12.4
302    - Fix memory leak when engine is destroyed
303    - Fix memory leak in http_client
304    - Fix gcc warning in unit tests
305
3062018-08-22
307
308    - 1.12.3
309    - [BUGFIX] Fix duplicate STREAM frame detection
310
3112018-08-20
312
313    - 1.12.2
314    - [BUGFIX] Update count of scheduled bytes when adjusting size of
315      an already-scheduled packet.
316    - Emit info instead of warning messages when stream is used in
317      unexpected ways.
318
3192018-08-17
320
321    - 1.12.0
322    - [FEATURE, API Change] Add support for certificate verification
323
3242018-08-16
325
326    - 1.11.1
327    - [BUGFIX] Fix STOP_WAITING frame processing in the new Q044 code
328
3292018-08-15
330
331    - 1.11.0
332    - [FEATURE] Add support for Q044.
333
3342018-08-09
335
336    - 1.10.2
337    - [BUGFIX] Don't go over limit when creating delayed streams
338
3392018-07-10
340
341    - 1.10.1
342    - [BUGFIX]  process connections after each batch of packets is read
343      This avoids a problem of accumulating a very large list of packets
344      (possible when speeds are high and socket's receive buffer is large)
345      and processing it all at once.
346    - If glibc is older than 2.17, link with rt.  This is necessary for
347      clock_getres(2).
348    - Add version macros to lsquic.h; remove unnecessary includes.
349
3502018-06-13
351
352    - [BUGFIX] allow multiple parallel connections by default
353
354      Use the original method of tracking connections by CIDs by default.
355      If zero-sized CID support is turned on, connections are tracked by
356      the address.  A new connection is not created if another connection
357      is using the same network address
358
3592018-05-30
360
361    - [FEATURE, API CHANGE] Support zero-sized CIDs in received packets
362
3632018-05-24
364
365    - Close connection properly when packet encryption fails
366
3672018-05-23
368
369    - [BUGFIX] Do not produce packet sequence gaps due to delayed packets
370
3712018-05-21
372
373    - [API Change] Add optional callback to call when handshake is done
374    - [API Change, BUGFIX] After send failure, wait until transport available
375
3762018-05-18
377
378    - [API] Expose useful lsquic_ver2str[] in lsquic.h
379    - [BUGFIX] Do not produce packet sequence gaps due to STREAM frame elision
380    - Improve checks of number of incoming streams limit and associated
381      error reporting.
382    - [BUGFIX] Command-line option `-6` now works correctly.
383
3842018-05-16
385
386    - [FEATURE] DNS resolution
387    - [BUGFIX] Frame insertion mis-ID as overlap instead of dup
388    - http_client: fix priority range generated by -E flag
389
3902018-05-09
391
392    - [FEATURE] Add support for Q043.
393    - Support for versions Q037, Q038, Q041, and Q042 has been removed.
394    - Fix typo in debug message.
395    - Fix code indentation.
396    - Add /* fallthru */ comment to stop newer gcc from complaining.
397    - Logger: fix compilation of optimized Windows build.
398
3992018-05-04
400
401    - [FEATURE] Add support for Q042.
402    - Remove comment: MSPC is obsolete (no code changes)
403    - Prog: use lsquic_str2ver() when processing -o version flag
404    - Remove unused CTIM and SRBF transport parameters
405    - Disable QUIC versions Q037 and Q038 by default
406    - Fix Windows compilation by including compat header file in
407      lshpack.c
408    - Address warnings produced by newer versions of gcc
409    - Future-proof: turn off -Werror
410
4112018-05-02
412
413    - [BUGFIX] Make lsquic_conn_quic_version() available
414    - Switch to using ls-hpack 1.1
415    - [BUGFIX] Do not ignore stream resets after receiving FIN
416
4172018-04-27
418
419    - HPACK: do not allow header block to end with table size update.
420
4212018-04-25
422
423    - [BUGFIX] Do not create gap in sent packnos when squeezing delayed
424      packets.
425    - [BUGFIX] sendctl checks for all unacked bytes, not just retx bytes.
426    - [BUGFIX] connections with blocked scheduled packets are not tickable
427      for sending.
428    - [BUGFIX] Conn is tickable if it wants to send a connection-level
429      frame.
430
4312018-04-23
432
433    - Fix busy loop: tickable must make progress.  When connection is
434      self-reporting as tickable, it must make progress when ticked.  There
435      are two issues:
436        1. If there are buffered packets, the connection is only tickable if
437           they can be sent out.
438        2. A connection is tickable if there are streams on the servicing
439           queue.  When the tick occurs, we must service the stream
440           independent of whether any packets are sent.
441    - Fix assertion in pacer which can be incorrect under some
442      conditions.
443    - cmake: do not turn on address sanitizer if in Travis.
444
4452018-04-20
446
447    - [BUGFIX] Fix bug in lsquic_engine_connect() exposed by yesterday's
448      changes.
449
4502018-04-19
451
452    - [BUGFIX] Add connection to Tickable Queue on stream write
453    - cmake: use MSVC variable instead of trying to detect
454    - engine: improve connection incref/decref logging
455    - stream: don't ignore errors that may occur on triggered flush
456    - connection: remove obsolete method
457    - engine: indicate connection as tickable if previous call went
458      over threshold
459
4602018-04-09
461
462    [API Change, OPTIMIZATION] Only process conns that need to be processed
463
464    The API is simplified: do not expose the user code to several
465    queues.  A "connection queue" is now an internal concept.
466    The user processes connections using the single function
467    lsquic_engine_process_conns().  When this function is called,
468    only those connections are processed that need to be processed.
469    A connection needs to be processed when:
470
471        1. New incoming packets have been fed to the connection.
472        2. User wants to read from a stream that is readable.
473        3. User wants to write to a stream that is writeable.
474        4. There are buffered packets that can be sent out.  (This
475           means that the user wrote to a stream outside of the
476           lsquic library callback.)
477        5. A control frame (such as BLOCKED) needs to be sent out.
478        6. A stream needs to be serviced or delayed stream needs to
479           be created.
480        7. An alarm rings.
481        8. Pacer timer expires.
482
483    To achieve this, the library places the connections into two
484    priority queues (min heaps):
485
486        1. Tickable Queue; and
487        2. Advisory Tick Time queue (ATTQ).
488
489    Each time lsquic_engine_process_conns() is called, the Tickable
490    Queue is emptied.  After the connections have been ticked, they are
491    queried again: if a connection is not being closed, it is placed
492    either in the Tickable Queue if it is ready to be ticked again or
493    it is placed in the Advisory Tick Time Queue.  It is assumed that
494    a connection always has at least one timer set (the idle alarm).
495
496    The connections in the Tickable Queue are arranged in the least
497    recently ticked order.  This lets connections that have been quiet
498    longer to get their packets scheduled first.
499
500    This change means that the library no longer needs to be ticked
501    periodically.  The user code can query the library when is the
502    next tick event and schedule it exactly.  When connections are
503    processed, only the tickable connections are processed, not *all*
504    the connections.  When there are no tick events, it means that no
505    timer event is necessary -- only the file descriptor READ event
506    is active.
507
508    The following are improvements and simplifications that have
509    been triggered:
510
511        - Queue of connections with incoming packets is gone.
512        - "Pending Read/Write Events" Queue is gone (along with its
513          history and progress checks).  This queue has become the
514          Tickable Queue.
515        - The connection hash no longer needs to track the connection
516          insertion order.
517
5182018-04-02
519
520    - [FEATURE] Windows support
521
522    - Reduce stack use -- outgoing packet batch is now allocated on the heap.
523
5242018-03-09
525
526    - [OPTIMIZATION] Merge series of ACKs if possible
527
528      Parsed single-range ACK frames (that is the majority of frames) are
529      saved in the connection and their processing is deferred until the
530      connection is ticked.  If several ACKs come in a series between
531      adjacent ticks, we check whether the latest ACK is a strict superset
532      of the saved ACK.  If it is, the older ACK is not processed.
533
534      If ACK frames can be merged, they are merged and only one of them is
535      either processed or saved.
536
537    - [OPTIMIZATION] Speed up ACK verification by simplifying send history.
538
539      Never generate a gap in the sent packet number sequence.  This reduces
540      the send history to a single number instead of potentially a series of
541      packet ranges and thereby speeds up ACK verification.
542
543      By default, detecting a gap in the send history is not fatal: only a
544      single warning is generated per connection.  The connection can continue
545      to operate even if the ACK verification code is not able to detect some
546      inconsistencies.
547
548    - [OPTIMIZATION] Rearrange the lsquic_send_ctl struct
549
550      The first part of struct lsquic_send_ctl now consists of members that
551      are used in lsquic_send_ctl_got_ack() (in the absense of packet loss,
552      which is the normal case).  To speed up reads and writes, we no longer
553      try to save space by using 8- and 16-bit integers.  Use regular integer
554      width for everything.
555
556    - [OPTIMIZATION] Cache size of sent packet.
557
558    - [OPTIMIZATION] Keep track of the largest ACKed in packet_out
559
560      Instead of parsing our own ACK frames when packet has been acked,
561      use the value saved in the packet_out structure when the ACK frame
562      was generated.
563
564    - [OPTIMIZATION] Take RTT sampling conditional out of ACK loop
565
566    - [OPTIMIZATION] ACK processing: only call clock_gettime() if needed
567
568    - [OPTIMIZATION] Several code-level optimizations to ACK processing.
569
570    - Fix: http_client: fix -I flag; switch assert() to abort()
571
5722018-02-26
573    - [API Change] lsquic_engine_connect() returns pointer to the connection
574      object.
575    - [API Change] Add lsquic_conn_get_engine() to get engine object from
576      connection object.
577    - [API Change] Add lsquic_conn_status() to query connection status.
578    - [API Change] Add add lsquic_conn_set_ctx().
579    - [API Change] Add new timestamp format, e.g. 2017-03-21 13:43:46.671345
580    - [OPTIMIZATION] Process handshake STREAM frames as soon as packet
581      arrives.
582    - [OPTIMIZATION] Do not compile expensive send controller sanity check
583      by default.
584    - [OPTIMIZATION] Add fast path to gquic_be_gen_reg_pkt_header.
585    - [OPTIMIZATION] Only make squeeze function call if necessary.
586    - [OPTIMIZATION] Speed up Q039 ACK frame parsing.
587    - [OPTIMIZATION] Fit most used elements of packet_out into first 64 bytes.
588    - [OPTIMIZATION] Keep track of scheduled bytes instead of calculating.
589    - [OPTIMIZATION] Prefetch next unacked packet when processing ACK.
590    - [OPTIMIZATION] Leverage fact that ACK ranges and unacked list are.
591      ordered.
592    - [OPTIMIZATION] Reduce function pointer use for STREAM frame generation
593    - Fix: reset incoming streams that arrive after we send GOAWAY.
594    - Fix: delay client on_new_conn() call until connection is fully set up.
595    - Fixes to buffered packets logic: splitting, STREAM frame elision.
596    - Fix: do not dispatch on_write callback if no packets are available.
597    - Fix WINDOW_UPDATE send and resend logic.
598    - Fix STREAM frame extension code.
599    - Fix: Drop unflushed data when stream is reset.
600    - Switch to tracking CWND using bytes rather than packets.
601    - Fix TCP friendly adjustment in cubic.
602    - Fix: do not generate invalid STOP_WAITING frames during high packet
603      loss.
604    - Pacer fixes.
605
6062017-12-18
607
608    - Fix: better follow cubic curve after idle period
609    - Fix: add missing parts to outgoing packet splitting code
610    - Fix: compilation using gcc 4.8.4
611
6122017-10-31
613
614    - Add APIs.txt -- describes LSQUIC APIs
615
6162017-10-31
617
618    - [API Change] Sendfile-like functionality is gone.  The stream no
619      longer opens files and deals with file descriptors.  (Among other
620      things, this makes the code more portable.)  Three writing functions
621      are provided:
622
623        lsquic_stream_write
624        lsquic_stream_writev
625        lsquic_stream_writef    (NEW)
626
627      lsquic_stream_writef() is given an abstract reader that has function
628      pointers for size() and read() functions which the user can implement.
629      This is the most flexible way.  lsquic_stream_write() and
630      lsquic_stream_writev() are now both implemented as wrappers around
631      lsquic_stream_writef().
632
633    - [OPTIMIZATION] When writing to stream, be it within or without the
634      on_write() callback, place data directly into packet buffer,
635      bypassing auxiliary data structures.  This reduces amount of memory
636      required, for the amount of data that can be written is limited
637      by the congestion window.
638
639      To support writes outside the on_write() callback, we keep N
640      outgoing packet buffers per connection which can be written to
641      by any stream.  One half of these are reserved for the highest
642      priority stream(s), the other half for all other streams.  This way,
643      low-priority streams cannot write instead of high-priority streams
644      and, on the other hand, low-priority streams get a chance to send
645      their packets out.
646
647      The algorithm is as follows:
648
649      - When user writes to stream outside of the callback:
650        - If this is the highest priority stream, place it onto the
651          reserved N/2 queue or fail.
652            (The actual size of this queue is dynamic -- MAX(N/2, CWND) --
653             rather than N/2, allowing high-priority streams to write as
654             much as can be sent.)
655        - If the stream is not the highest priority, try to place the
656          data onto the reserved N/2 queue or fail.
657      - When tick occurs *and* more packets can be scheduled:
658        - Transfer packets from the high N/2 queue to the scheduled
659          queue.
660        - If more scheduling is allowed:
661          - Call on_write callbacks for highest-priority streams,
662            placing resulting packets directly onto the scheduled queue.
663        - If more scheduling is allowed:
664          - Transfer packets from the low N/2 queue to the scheduled
665            queue.
666        - If more scheduling is allowed:
667          - Call on_write callbacks for non-highest-priority streams,
668            placing resulting packets directly onto the scheduled queue
669
670      The number N is currently 20, but it could be varied based on
671      resource usage.
672
673    - If stream is created due to incoming headers, make headers readable
674      from on_new.
675
676    - Outgoing packets are no longer marked non-writeable to prevent placing
677      more than one STREAM frame from the same stream into a single packet.
678      This property is maintained via code flow and an explicit check.
679      Packets for stream data are allocated using a special function.
680
681    - STREAM frame elision is cheaper, as we only perform it if a reset
682      stream has outgoing packets referencing it.
683
684    - lsquic_packet_out_t is smaller, as stream_rec elements are now
685      inside a union.
686
6872017-10-12
688
689    - Do not send RST_STREAM when stream is closed for reading
690    - Raise maximum header size from 4K to 64K
691    - Check header name and value lengths against maximum imposed by HPACK
692    - Fix NULL dereference in stream flow controller
693
6942017-10-09
695
696    - Hide handshake implementation behind a set of function pointers
697    - Use monotonically increasing clock
698    - Make sure that retx delay is not larger than the max of 60 seconds
699
7002017-09-29
701
702    - A few fixes to code and README
703
7042017-09-28
705
706    - Add support for Q041; drop support for Q040
707
7082017-09-27
709
710    - Fix CMakeLists.txt: BoringSSL include and lib was mixed up
711
7122017-09-26
713
714    - Add support for Mac OS
715    - Add support for Raspberry Pi
716    - Fix BoringSSL compilation: include <openssl/hmac.h> explicitly
717
7182017-09-22
719
720    - Initial release
721