Create the snapshot of `CConnman::vNodes` to operate on earlier in
`CConnman::SocketHandler()`, before calling `CConnman::SocketEvents()`
and pass the `vNodes` copy from the snapshot to `SocketEvents()`.
This will keep the refcount of each node incremented during
`SocketEvents()` so that the `CNode` object is not destroyed before
`SocketEvents()` has finished.
Currently in `SocketEvents()` we only remember file descriptor numbers
(when not holding `CConnman::cs_vNodes`) which is safe, but we will
change this to remember pointers to `CNode::m_sock`.
The following pattern was duplicated in CConnman:
```cpp
lock
create a copy of vNodes, add a reference to each one
unlock
... use the copy ...
lock
release each node from the copy
unlock
```
Put that code in a RAII helper that reduces it to:
```cpp
create snapshot "snap"
... use the copy ...
// release happens when "snap" goes out of scope
```
In some cases addresses come from an external source as a string or as a
`struct sockaddr_in6`, without a tag to tell whether it is a private
IPv6 or a CJDNS address. In those cases interpret the address as a CJDNS
address instead of an IPv6 address if `-cjdnsreachable` is set and the
seemingly-IPv6-address belongs to `fc00::/8`. Those external sources are:
* `-externalip=`
* `-bind=`
* UPnP
* `getifaddrs(3)` (called through `-discover`)
* `addnode`
* `connect`
* incoming connections (returned by `accept(2)`)
f3e451bebf [net] Replace GetID() with id in TransportDeserializer constructor (Troy Giorshev)
8c96008ab1 [net] Don't return an optional from TransportDeserializer::GetMessage() (Troy Giorshev)
Pull request description:
Also, access mapRecvBytesPerMsgCmd with `at()` not `find()`. This
throws an error if COMMAND_OTHER doesn't exist, which should never
happen. `find()` instead just accessed the last element, which could make
debugging more difficult.
Resolves review comments from PR19107:
- https://github.com/bitcoin/bitcoin/pull/19107#discussion_r478718436
- https://github.com/bitcoin/bitcoin/pull/19107#discussion_r478714497
ACKs for top commit:
theStack:
Code-review ACK f3e451bebf
ryanofsky:
Code review ACK f3e451bebf. Changes since last review in https://github.com/bitcoin/bitcoin/pull/20364#pullrequestreview-534369904 were simplifying by dropping the third commit, rebasing, and cleaning up some style & comments in the first commit.
Tree-SHA512: 37de4b25646116e45eba50206e82ed215b0d9942d4847a172c104da4ed76ea4cee29a6fb119f3c34106a9b384263c576cb8671d452965a468f358d4a3fa3c003
021f86953e [style] Run changed files through clang formatter. (Amiti Uttarwar)
375750387e scripted-diff: Rename CAddrInfo to AddrInfo (Amiti Uttarwar)
dd8f7f2500 scripted-diff: Rename CAddrMan to AddrMan (Amiti Uttarwar)
3c263d3f63 [includes] Fix up included files (Amiti Uttarwar)
29727c2aa1 [doc] Update comments (Amiti Uttarwar)
14f9e000d0 [refactor] Update GetAddr_() function signature (Amiti Uttarwar)
40acd6fc9a [move-only] Move constants to test-only header (Amiti Uttarwar)
7cf41bbb38 [addrman] Change CAddrInfo access (Amiti Uttarwar)
e3f1ea659c [move-only] Move CAddrInfo to test-only header file (Amiti Uttarwar)
7cba9d5618 [net, addrman] Remove external dependencies on CAddrInfo objects (Amiti Uttarwar)
8af5b54f97 [addrman] Introduce CAddrMan::Impl to encapsulate addrman implementation. (Amiti Uttarwar)
f2e5f38f09 [move-only] Match ordering of CAddrMan declarations and definitions (Amiti Uttarwar)
5faa7dd6d8 [move-only] Move CAddrMan function definitions to cpp (Amiti Uttarwar)
Pull request description:
Introduce the pimpl pattern for AddrMan to separate the implementation details from the externally used object representation. This reduces compile-time dependencies and conceptually clarifies AddrMan's interface from the implementation specifics.
Since the unit & fuzz tests currently rely on accessing AddrMan internals, this PR introduces addrman_impl.h, which is exclusively imported by addrman.cpp and test files.
ACKs for top commit:
jnewbery:
ACK 021f86953e
GeneFerneau:
utACK [021f869](021f86953e)
mzumsande:
ACK 021f86953e
rajarshimaitra:
Concept + Code Review ACK 021f86953e
theuni:
ACK 021f86953e
Tree-SHA512: aa70cb77927a35c85230163c0cf6d3872382d79048b0fb79341493caa46f8e91498cb787d8b06aba4da17b2f921f2230e73f3d66385519794fff86a831b3a71d
4747da3a5b Add syscall sandboxing (seccomp-bpf) (practicalswift)
Pull request description:
Add experimental syscall sandboxing using seccomp-bpf (Linux secure computing mode).
Enable filtering of system calls using seccomp-bpf: allow only explicitly allowlisted (expected) syscalls to be called.
The syscall sandboxing implemented in this PR is an experimental feature currently available only under Linux x86-64.
To enable the experimental syscall sandbox the `-sandbox=<mode>` option must be passed to `bitcoind`:
```
-sandbox=<mode>
Use the experimental syscall sandbox in the specified mode
(-sandbox=log-and-abort or -sandbox=abort). Allow only expected
syscalls to be used by bitcoind. Note that this is an
experimental new feature that may cause bitcoind to exit or crash
unexpectedly: use with caution. In the "log-and-abort" mode the
invocation of an unexpected syscall results in a debug handler
being invoked which will log the incident and terminate the
program (without executing the unexpected syscall). In the
"abort" mode the invocation of an unexpected syscall results in
the entire process being killed immediately by the kernel without
executing the unexpected syscall.
```
The allowed syscalls are defined on a per thread basis.
I've used this feature since summer 2020 and I find it to be a helpful testing/debugging addition which makes it much easier to reason about the actual capabilities required of each type of thread in Bitcoin Core.
---
Quick start guide:
```
$ ./configure
$ src/bitcoind -regtest -debug=util -sandbox=log-and-abort
…
2021-06-09T12:34:56Z Experimental syscall sandbox enabled (-sandbox=log-and-abort): bitcoind will terminate if an unexpected (not allowlisted) syscall is invoked.
…
2021-06-09T12:34:56Z Syscall filter installed for thread "addcon"
2021-06-09T12:34:56Z Syscall filter installed for thread "dnsseed"
2021-06-09T12:34:56Z Syscall filter installed for thread "net"
2021-06-09T12:34:56Z Syscall filter installed for thread "msghand"
2021-06-09T12:34:56Z Syscall filter installed for thread "opencon"
2021-06-09T12:34:56Z Syscall filter installed for thread "init"
…
# A simulated execve call to show the sandbox in action:
2021-06-09T12:34:56Z ERROR: The syscall "execve" (syscall number 59) is not allowed by the syscall sandbox in thread "msghand". Please report.
…
Aborted (core dumped)
$
```
---
[About seccomp and seccomp-bpf](https://en.wikipedia.org/wiki/Seccomp):
> In computer security, seccomp (short for secure computing mode) is a facility in the Linux kernel. seccomp allows a process to make a one-way transition into a "secure" state where it cannot make any system calls except exit(), sigreturn(), and read() and write() to already-open file descriptors. Should it attempt any other system calls, the kernel will terminate the process with SIGKILL or SIGSYS. In this sense, it does not virtualize the system's resources but isolates the process from them entirely.
>
> […]
>
> seccomp-bpf is an extension to seccomp that allows filtering of system calls using a configurable policy implemented using Berkeley Packet Filter rules. It is used by OpenSSH and vsftpd as well as the Google Chrome/Chromium web browsers on Chrome OS and Linux. (In this regard seccomp-bpf achieves similar functionality, but with more flexibility and higher performance, to the older systrace—which seems to be no longer supported for Linux.)
ACKs for top commit:
laanwj:
Code review and lightly tested ACK 4747da3a5b
Tree-SHA512: e1c28e323eb4409a46157b7cc0fc29a057ba58d1ee2de268962e2ade28ebd4421b5c2536c64a3af6e9bd3f54016600fec88d016adb49864b63edea51ad838e17
CAddrInfo objects are an implementation detail of how AddrMan manages and adds
metadata to different records. Encapsulate this logic by updating Select &
SelectTriedCollision to return the additional info that the callers need.
330d3aa1a2 refactor: net: avoid duplicate map lookups to `mapLocalHost` (Sebastian Falbesoner)
Pull request description:
This simple refactoring PR aims to avoid duplicate lookups to `mapLocalHost`: instead of calling `count()` (to first find out whether a key is in the map) and then `operator[]` (to get the value to the passed key, or default-construct one if not found), use either
* `find()` and dereference the returned iterator (for simple lookups), see https://www.cplusplus.com/reference/map/map/find/
* `emplace()` and use the returned <iterator, inserted> pair (for lookups where a new element should be inserted if the key isn't found), see https://www.cplusplus.com/reference/map/map/emplace/
ACKs for top commit:
naumenkogs:
ACK 330d3aa1a2
jonatack:
Code review ACK 330d3aa1a2 plus rebase to master + debug build
Tree-SHA512: d13da6a927ff561eee8ac6b093bf3586dfe31d6c94173a5a6d8f3698e0ee224fb394d3635155d5141c165da59d2c2c37260122eb4f2e8bcda3e8a29b901d213e
853c4edb70 [net] Remove asmap argument from CNode::CopyStats() (John Newbery)
9fd5618610 [asmap] Make DecodeAsmap() a utility function (John Newbery)
bfdf4ef334 [asmap] Remove SanityCheckASMap() from netaddress (John Newbery)
07a9eccb60 [net] Remove CConnman::Options.m_asmap (John Newbery)
Pull request description:
These small cleanups to the asmap code are the first 4 commits from #22910. They're minor improvements that are independently useful whether or not 22910 is merged.
ACKs for top commit:
naumenkogs:
ACK 853c4edb70
theStack:
Concept and code-review ACK 853c4edb70🗺️
fanquake:
ACK 853c4edb70
Tree-SHA512: 64783743182592ac165df6ff8d18870b63861e9204ed722c207fca6938687aac43232a5ac4d8228cf8b92130ab0349de1b410a2467bb5a9d60dd9a7221b3b85b
The class only stores the file path, reading it from a global. Globals
are confusing and make testing harder.
The method reading from a stream does not even use any class members, so
putting it in a class is also confusing.
724c497562 [fuzz] Add ConsumeAsmap() function (John Newbery)
5840476714 [addrman] Make m_asmap private (John Newbery)
f9002cb5db [net] Rename the copyStats arg from m_asmap to asmap (John Newbery)
f572f2b204 [addrman] Set m_asmap in CAddrMan initializer list (John Newbery)
593247872d [net] Remove CConnMan::SetAsmap() (John Newbery)
50fd77045e [init] Read/decode asmap before constructing addrman (John Newbery)
Pull request description:
Commit 181a1207 introduced an initialization order bug: CAddrMan's m_asmap must be set before deserializing peers.dat.
The first commit restores the correct initialization order. The remaining commits make `CAddrMan::m_asmap` usage safer:
- don't reach into `CAddrMan`'s internal data from `CConnMan`
- set `m_asmap` in the initializer list and make it const
- make `m_asmap` private, and access it (as a reference to const) from a getter.
This ensures that peers.dat deserialization must happen after setting m_asmap, since m_asmap is set during CAddrMan construction.
ACKs for top commit:
mzumsande:
Tested ACK 724c497562
amitiuttarwar:
code review but utACK 724c497562
naumenkogs:
utACK 724c497562
vasild:
ACK 724c497562
MarcoFalke:
review ACK 724c497562👫
Tree-SHA512: 684a4cf9e3d4496c9997fb2bc4ec874809987055c157ec3fad1d2143b8223df52b5a0af787d028930b27388c8efeba0aeb2446cb35c337a5552ae76112ade726
Improve readability of code, simplify future scripted diff cleanup PRs, and be
more consistent with naming for GetBoolArg.
This will also be useful for replacing runtime settings type checking
with compile time checking.
-BEGIN VERIFY SCRIPT-
git grep -l GetArg | xargs sed -i 's/GetArg(\([^)]*\( [0-9]\+\|-1\|port\|BaseParams().RPCPort()\|Params().GetDefaultPort()\|_TIMEOUT\|Height\|_WORKQUEUE\|_THREADS\|_CONNECTIONS\|LIMIT\|SigOp\|Bytes\|_VERSION\|_AGE\|_CHECKS\|Checks() ? 1 : 0\|_BANTIME\|Cache\|BLOCKS\|LEVEL\|Weight\|Version\|BUFFER\|TARGET\|WEIGHT\|TXN\|TRANSACTIONS\|ADJUSTMENT\|i64\|Size\|nDefault\|_EXPIRY\|HEIGHT\|SIZE\|SNDHWM\|_TIME_MS\)\))/GetIntArg(\1)/g'
-END VERIFY SCRIPT-
Co-authored-by: Hennadii Stepanov <32963518+hebasto@users.noreply.github.com>
The m_ prefix indicates that a variable is a data member. Using it as
a parameter name is misleading.
Also update the name of the function from copyStats to CopyStats to
comply with our style guide.
This logic is a no-op since it was introduced in commit
f9f5cfc506.
m_addr_name is never initialized to the empty string, because
ToStringIPPort never returns an empty string.
5730a43703 test: Add functional test for AddrFetch connections (Martin Zumsande)
c34ad3309f net, rpc: Enable AddrFetch connections for functional testing (Martin Zumsande)
533500d907 p2p: Add timeout for AddrFetch peers (Martin Zumsande)
b6c5d1e450 p2p: AddrFetch - don't disconnect on self-announcements (Martin Zumsande)
Pull request description:
AddrFetch connections (old name: oneshots) are intended to be short-lived connections on which we ask a peer for addresses via `getaddr` and disconnect after receiving them.
This is done by disconnecting after receiving the first `addr`. However, it is no longer working as intended, because nowadays, the first `addr` a typical bitcoin core node sends is its self-announcement.
So we'll disconnect before the peer gets a chance to answer our `getaddr`.
I checked that this affects both `-seednode` peers specified manually, and DNS seeds when AddrFetch is used as a fallback if DNS doesn't work for us.
The current behavior of getting peers via AddrFetch when starting with an empty addrman would be to connect to the peer, receive its self-announcement and add it to addrman, disconnect, reconnect to the same peer again as a full outbound (no other addresses in addrman) and then receive more `addr`. This is silly and not in line with AddrFetch peer being intended to be short-lived peers.
Fix this by only disconnecting after receiving an `addr` message of size > 1.
[Edit] As per review discussion, this PR now also adds a timeout after which we disconnect if we haven't received any suitable `addr`, and a functional test.
ACKs for top commit:
amitiuttarwar:
reACK 5730a43703
naumenkogs:
ACK 5730a43703
jnewbery:
ACK 5730a43703
Tree-SHA512: 8a81234f37e827705138eb254223f7f3b3bf44a06cb02126fc7990b0d231b9bd8f07d38d185cc30d55bf35548a6fdc286b69602498d875b937e7c58332158bf9
b1d905c225 p2p: earlier continuation when no remaining eviction candidates (Vasil Dimov)
c9e8d8f9b1 p2p: process more candidates per protection iteration (Jon Atack)
02e411ec45 p2p: iterate eviction protection only on networks having candidates (Jon Atack)
5adb064574 bench: add peer eviction protection benchmarks (Jon Atack)
566357f8f7 refactor: move GetRandomNodeEvictionCandidates() to test utilities (Jon Atack)
Pull request description:
This follow-up to #21261 improves `ProtectEvictionCandidatesByRatio()` for better performance.
Benchmarks are added; the performance improvement is between 2x and 5x for the benchmarked cases (CPU 2.50GHz, Turbo off, performance mode, Debian Clang 11 non-debug build).
```
$ ./src/bench/bench_bitcoin -filter="EvictionProtection*.*"
```
The refactored code is well-covered by existing unit tests and also a fuzzer.
- `$ ./src/test/test_bitcoin -t net_peer_eviction_tests`
- `$ FUZZ=node_eviction ./src/test/fuzz/fuzz ../qa-assets/fuzz_seed_corpus/node_eviction`
ACKs for top commit:
klementtan:
Tested and code review ACK b1d905c2.
vasild:
ACK b1d905c225
jarolrod:
ACK b1d905c225
Tree-SHA512: a3a6607b9ea2fec138da9780c03f63e177b6712091c5a3ddc3804b896a7585216446310280791f5e20cc023d02d2f03a4139237e12b5c1d7f2a1fa1011610e96
4101ec9d2e doc: mention that we enforce port=0 in I2P (Vasil Dimov)
e0a2b390c1 addrman: reset I2P ports to 0 when loading from disk (Vasil Dimov)
41cda9d075 test: ensure I2P ports are handled as expected (Vasil Dimov)
4f432bd738 net: do not connect to I2P hosts on port!=0 (Vasil Dimov)
1f096f091e net: distinguish default port per network (Vasil Dimov)
aeac3bce3e net: change I2P seeds' ports to 0 (Vasil Dimov)
38f900290c net: change assumed I2P port to 0 (Vasil Dimov)
Pull request description:
_This is an alternative to https://github.com/bitcoin/bitcoin/pull/21514, inspired by https://github.com/bitcoin/bitcoin/pull/21514#issuecomment-815049933. They are mutually exclusive. Just one of them should be merged._
Change assumed ports for I2P to 0 (instead of the default 8333) as this is closer to what actually happens underneath with SAM 3.1 (https://github.com/bitcoin/bitcoin/pull/21514#issuecomment-812632520, https://github.com/bitcoin/bitcoin/pull/21514#issuecomment-816564719).
Don't connect to I2P peers with advertised port != 0 (we don't specify a port to our SAM 3.1 proxy and it always connects to port = 0).
Note, this change:
* Keeps I2P addresses with port != 0 in addrman and relays them to others via P2P gossip. There may be non-bitcoin-core-22.0 peers using SAM 3.2 and for them such addresses may be useful.
* Silently refuses to connect to I2P hosts with port != 0. This is ok for automatically chosen peers from addrman. Not so ok for peers provided via `-addnode` or `-connect` - a user who specifies `foo.b32.i2p:1234` (non zero port) may wonder why "nothing is happening".
Fixes#21389
ACKs for top commit:
laanwj:
Code review ACK 4101ec9d2e
jonatack:
re-ACK 4101ec9d2e per `git range-diff efff9c3 0b0ee03 4101ec9`, built with DDEBUG_ADDRMAN, did fairly extensive testing on mainnet both with and without a peers.dat / -dnsseeds=0 to test boostrapping.
Tree-SHA512: 0e3c019e1dc05e54f559275859d3450e0c735596d179e30b66811aad9d5b5fabe3dcc44571e8f7b99f9fe16453eee393d6e153454dd873b9ff14907d4e6354fe
2feec3ce31 net: don't bind on 0.0.0.0 if binds are restricted to Tor (Vasil Dimov)
Pull request description:
The semantic of `-bind` is to restrict the binding only to some address.
If not specified, then the user does not care and we bind to `0.0.0.0`.
If specified then we should honor the restriction and bind only to the
specified address.
Before this change, if no `-bind` is given then we would bind to
`0.0.0.0:8333` and to `127.0.0.1:8334` (incoming Tor) which is ok -
the user does not care to restrict the binding.
However, if only `-bind=addr:port=onion` is given (without ordinary
`-bind=`) then we would bind to `addr:port` _and_ to `0.0.0.0:8333` in
addition.
Change the above to not do the additional bind: if only
`-bind=addr:port=onion` is given (without ordinary `-bind=`) then bind
to `addr:port` (only) and consider incoming connections to that as Tor
and do not advertise it. I.e. a Tor-only node.
ACKs for top commit:
laanwj:
Code review ACK 2feec3ce31
jonatack:
utACK 2feec3ce31 per `git diff a004833 2feec3c`
hebasto:
ACK 2feec3ce31, tested on Linux Mint 20.1 (x86_64):
Tree-SHA512: a04483af601706da928958b92dc560f9cfcc78ab0bb9d74414636eed1c6f29ed538ce1fb5a17d41ed82c9c9a45ca94899d0966e7ef93da809c9bcdcdb1d1f040
in ProtectEvictionCandidatesByRatio().
With this change, `if (n.count == 0) continue;` will be true
if a network had candidates protected in the first iterations
and has no candidates remaining to be protected in later iterations.
Co-authored-by: Jon Atack <jon@atack.com>
for the usual case when some of the protected networks
don't have eviction candidates, to reduce the number
of iterations in ProtectEvictionCandidatesByRatio().
Picks up an idea in ef411cd2 that I had dropped.
in ProtectEvictionCandidatesByRatio().
Thank you to Vasil Dimov, whose suggestions during a post-merge
discussion about PR 21261 reminded me that I had done this in
earlier versions of the PR, e.g. commits like ef411cd2.
Co-authored-by: Vasil Dimov <vd@FreeBSD.org>
The semantic of `-bind` is to restrict the binding only to some address.
If not specified, then the user does not care and we bind to `0.0.0.0`.
If specified then we should honor the restriction and bind only to the
specified address.
Before this change, if no `-bind` is given then we would bind to
`0.0.0.0:8333` and to `127.0.0.1:8334` (incoming Tor) which is ok -
the user does not care to restrict the binding.
However, if only `-bind=addr:port=onion` is given (without ordinary
`-bind=`) then we would bind to `addr:port` _and_ to `0.0.0.0:8333` in
addition.
Change the above to not do the additional bind: if only
`-bind=addr:port=onion` is given (without ordinary `-bind=`) then bind
to `addr:port` (only) and consider incoming connections to that as Tor
and do not advertise it. I.e. a Tor-only node.
79c02c88b3 Randomize message processing peer order (Pieter Wuille)
Pull request description:
Right now, the message handling loop iterates the list of nodes always in the same order: the order they were connected in (see the `vNodes` vector). For some parts of the net processing logic, this order matters. Transaction requests are assigned explicitly to peers since #19988, but many other parts of processing work on a "first-served-by-loop-first" basis, such as block downloading. If peers can predict this ordering, it may be exploited to cause delays.
As there isn't anything particularly optimal about the current ordering, just make it unpredictable by randomizing.
Reported by Crypt-iQ.
ACKs for top commit:
jnewbery:
ACK 79c02c88b3
Crypt-iQ:
ACK 79c02c88b3
sdaftuar:
utACK 79c02c88b3
achow101:
Code Review ACK 79c02c88b3
jamesob:
crACK 79c02c88b3
jonatack:
ACK 79c02c88b3
vasild:
ACK 79c02c88b3
theStack:
ACK 79c02c88b3
Tree-SHA512: 9a87c4dcad47c2d61b76c4f37f59674876b78f33f45943089bf159902a23e12de7a5feae1a73b17cbc3f2e37c980ecf0f7fd86af9e6fa3a68099537a3c82c106
This commit extends our inbound eviction protection to I2P peers to
favorise the diversity of peer connections, as peers connected
through the I2P network are otherwise disadvantaged by our eviction
criteria for their higher latency (higher min ping times) relative
to IPv4 and IPv6 peers, as well as relative to Tor onion peers.
The `networks` array is order-dependent in the case of a tie in
candidate counts between networks (earlier array members receive
priority in the case of a tie).
Therefore, we place I2P candidates before localhost and onion ones
in terms of opportunity to recover unused remaining protected slots
from the previous iteration, guesstimating that most nodes allowing
both onion and I2P inbounds will have more onion peers, followed by
localhost, then I2P, as I2P support is only being added in the
upcoming v22.0 release.
with a more abstract framework to allow easily extending inbound
eviction protection to peers connected through new higher-latency
networks that are disadvantaged by our inbound eviction criteria,
such as I2P and perhaps other BIP155 networks in the future like
CJDNS. This is a change in behavior.
The algorithm is a basically a multi-pass knapsack:
- Count the number of eviction candidates in each of the disadvantaged
privacy networks.
- Sort the networks from lower to higher candidate counts, so that
a network with fewer candidates will have the first opportunity
for any unused slots remaining from the previous iteration. In
the case of a tie in candidate counts, priority is given by array
member order from first to last, guesstimated to favor more unusual
networks.
- Iterate through the networks in this order. On each iteration,
allocate each network an equal number of protected slots targeting
a total number of candidates to protect, provided any slots remain
in the knapsack.
- Protect the candidates in that network having the longest uptime,
if any in that network are present.
- Continue iterating as long as we have non-allocated slots
remaining and candidates available to protect.
Localhost peers are treated as a network like Tor or I2P by aliasing
them to an unused Network enumerator: Network::NET_MAX.
The goal is to favorise diversity of our inbound connections.
Credit to Vasil Dimov for improving the algorithm from single-pass
to multi-pass to better allocate unused protection slots.
Co-authored-by: Vasil Dimov <vd@FreeBSD.org>
as EraseLastKElements() called in the next line performs the same operation.
Thanks to Martin Zumsande (lightlike) for seeing this while reviewing.
Co-authored-by: Martin Zumsande <mzumsande@gmail.com>
ffff0d0442 refactor: Switch serialize to uint8_t (1/n) (MarcoFalke)
Pull request description:
Replace `char` -> `uint8_t` in serialization where a sign doesn't make sense (char might be signed/unsigned).
ACKs for top commit:
practicalswift:
cr ACK ffff0d0442: patch looks correct and commit hash is ffffresh (was bbbbadass)
kristapsk:
ACK ffff0d0442
Tree-SHA512: cda682280c21d37cc3a6abd62569732079b31d18df3f157aa28bed80bd6f9f29a7db5c133b1f57b3a8f8d5ba181a76e473763c6e26a2df6d9244813f56f893ee
fe3d17df04 net: ignore block-relay-only peers when skipping DNS seed (Anthony Towns)
Pull request description:
Since #17428 bitcoind will attempt to reconnect to two block-relay-only anchors before doing any other outbound connections. When determining whether to use DNS seeds, it will currently see these two peers and decide "we're connected to the p2p network, so no need to lookup DNS" -- but block-relay-only peers don't do address relay, so if your address book is full of invalid addresses (apart from your anchors) this behaviour will prevent you from recovering from that situation.
This patch changes it so that it only skips use of DNS seeds when there are two full-outbound peers, not just block-relay-only peers.
ACKs for top commit:
Sjors:
utACK fe3d17d
amitiuttarwar:
ACK fe3d17df04, this impacts the very common case where we stop/start a node, persisting anchors & have a non-empty addrman (although, to be clear, wouldn't be particularly problematic in the common cases where the addrman has valid addresses)
mzumsande:
ACK fe3d17df04
jonatack:
ACK fe3d17df04
prayank23:
tACK fe3d17df04
Tree-SHA512: 9814b0d84321d7f45b5013eb40c420a0dd93bf9430f5ef12dce50d1912a18d5de2070d890a8c6fe737a3329b31059b823bc660b432d5ba21f02881dc1d951e94
0829516d1f [refactor] Remove unused ForEachNodeThen() template (John Newbery)
09cc66c00e scripted-diff: rename address relay fields (John Newbery)
76568a3351 [net processing] Move addr relay data and logic into net processing (John Newbery)
caba7ae8a5 [net processing] Make RelayAddress() a member function of PeerManagerImpl (John Newbery)
86acc96469 [net processing] Take NodeId instead of CNode* as originator for RelayAddress() (John Newbery)
Pull request description:
This continues the work of moving application layer data into net_processing, by moving all addr data into the new Peer object added in #19607.
For motivation, see #19398.
ACKs for top commit:
laanwj:
Code review ACK 0829516d1f
mzumsande:
ACK 0829516d1f, reviewed the code and ran tests.
sipa:
utACK 0829516d1f
hebasto:
re-ACK 0829516d1f
Tree-SHA512: efe0410fac288637f203eb37d1999910791e345872d37e1bd5cde50e25bb3cb1c369ab86b3a166ffd5e06ee72e4508aa2c46d658be6a54e20b4f220d2f57d0a6
7075f604e8 scripted-diff: update noban documentation in net_processing.cpp (Jon Atack)
a95540cf43 scripted-diff: rename NetPermissionFlags enumerators (Jon Atack)
810d0929c1 p2p, refactor: make NetPermissionFlags a uint32 enum class (Jon Atack)
7b55a94497 p2p: NetPermissions::HasFlag() pass flags param by value (Jon Atack)
91f6e6e6d1 scripted-diff: add NetPermissionFlags scopes where not already present (Jon Atack)
Pull request description:
While reviewing #20196, I noticed the `NetPermissionFlags` enums are frequently called as if they were scoped, yet are still global. This patch upgrades `NetPermissionFlags` to a scoped class enum and updates the enumerator naming, similarly to #19771. See https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#enum-enumerations for more info.
This change would eliminate the class of bugs like https://github.com/bitcoin/bitcoin/pull/20196#discussion_r610770148 and #21644, as only defined operations on the flags would compile.
ACKs for top commit:
laanwj:
Code review ACK 7075f604e8
vasild:
ACK 7075f604e8
Tree-SHA512: 7fcea66ee499f059efc78c934b5f729b3c8573fe304dee2c27c837c2f662b89324790568246d75b2a574cf9f059b42d3551d928996862f4358055eb43521e6f4
105941b726 net: use stronger AddLocal() for our I2P address (Vasil Dimov)
Pull request description:
There are two issues:
### 1. Our I2P address not added to local addresses.
* `externalip=` is used with an IPv4 address (this sets automatically `discover=0`)
* No `discover=1` is used
* `i2psam=` is used
* No `externalip=` is used for our I2P address
* `listenonion=1 torcontrol=` are used
In this case `AddLocal(LOCAL_MANUAL)` [is used](94f83534e4/src/torcontrol.cpp (L354)) for our `.onion` address and `AddLocal(LOCAL_BIND)` [for our](94f83534e4/src/net.cpp (L2247)) `.b32.i2p` address, the latter being [ignored](94f83534e4/src/net.cpp (L232-L233)) due to `discover=0`.
### 2. Our I2P address removed from local addresses even if specified with `externalip=` on I2P proxy restart.
* `externalip=` is used with our I2P address (this sets automatically `discover=0`)
* No `discover=1` is used
* `i2psam=` is used
In this case, initially `externalip=` causes our I2P address to be [added](94f83534e4/src/init.cpp (L1266)) with `AddLocal(LOCAL_MANUAL)` which overrides `discover=0` and works as expected. However, if later the I2P proxy is shut down [we do](94f83534e4/src/net.cpp (L2234)) `RemoveLocal()` in order to stop advertising our I2P address (since we have lost I2P connectivity). When the I2P proxy is started and we reconnect to it, restoring the I2P connectivity, [we do](94f83534e4/src/net.cpp (L2247)) `AddLocal(LOCAL_BIND)` which does nothing due to `discover=0`.
To resolve those two issues, use `AddLocal(LOCAL_MANUAL)` for I2P which is also what we do with Tor.
ACKs for top commit:
laanwj:
Code review ACK 105941b726
Tree-SHA512: 0c9daf6116b8d9c34ad7e6e9bbff6e8106e94e4394a815d7ae19287aea22a8c7c4e093c8dd8c58a4a1b1412b2575a9b42b8a93672c8d17f11c24508c534506c7
- drop redundant PF_ permission flags prefixes
- drop ALL_CAPS naming per https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#Renum-caps
- rename IsImplicit to Implicit
-BEGIN VERIFY SCRIPT-
s() { git grep -l "$1" src | xargs sed -i "s/$1/$2/g"; }
s 'PF_NONE' 'None'
s 'PF_BLOOMFILTER' 'BloomFilter'
s 'PF_RELAY' 'Relay'
s 'PF_FORCERELAY' 'ForceRelay'
s 'PF_DOWNLOAD' 'Download'
s 'PF_NOBAN' 'NoBan'
s 'PF_MEMPOOL' 'Mempool'
s 'PF_ADDR' 'Addr'
s 'PF_ISIMPLICIT' 'Implicit'
s 'PF_ALL' 'All'
-END VERIFY SCRIPT-
-BEGIN VERIFY SCRIPT-
s() { git grep -l "$1" -- 'src' ':!src/net_permissions.h' | xargs sed -i -E "s/([^:])$1/\1NetPermissionFlags::$1/"; }
s 'PF_NONE'
s 'PF_BLOOMFILTER'
s 'PF_RELAY'
s 'PF_FORCERELAY'
s 'PF_DOWNLOAD'
s 'PF_NOBAN'
s 'PF_MEMPOOL'
s 'PF_ADDR'
s 'PF_ISIMPLICIT'
s 'PF_ALL'
-END VERIFY SCRIPT-
Co-authored-by: Hennadii Stepanov <32963518+hebasto@users.noreply.github.com>
792be53d3e refactor: Replace std::bind with lambdas (Hennadii Stepanov)
a508f718f3 refactor: Use appropriate thread constructor (Hennadii Stepanov)
30e4448215 refactor: Make TraceThread a non-template free function (Hennadii Stepanov)
Pull request description:
This PR does not change behavior.
Its goal is to improve readability and maintainability of the code.
ACKs for top commit:
jnewbery:
utACK 792be53d3e
jonatack:
tACK 792be53d3e
MarcoFalke:
cr ACK 792be53d3e
Tree-SHA512: a03142f04f370f6bc02bd3ddfa870819b51740fcd028772241d68c84087f95a2d78207cbd5edb3f7c636fcf2d76192d9c59873f8f0af451d3b05c0cf9cf234df
36fb036d25 p2p: allow NetPermissions::ClearFlag() only with PF_ISIMPLICIT (Jon Atack)
4e0d5788ba test: add net permissions noban/download unit test coverage (Jon Atack)
dde69f20a0 p2p, bugfix: use NetPermissions::HasFlag() in CConnman::Bind() (Jon Atack)
Pull request description:
This is a bugfix follow-up to #16248 and #19191 that was noticed in #21506. Both v0.21 and master are affected.
Since #19191, noban is a multi-flag that implies download, so the conditional in `CConnman::Bind()` using a bitwise AND on noban will return the same result for both the noban status and the download status. This means that download peers are incorrectly not being added to local addresses because they are mistakenly seen as noban peers.
The second commit adds unit test coverage to illustrate and test the noban/download relationship and the `NetPermissions` operations involving them.
The final commit adds documentation and disallows calling `NetPermissions::ClearFlag()` with any second param other than `NetPermissionFlags` "implicit" -- per current usage in the codebase -- because `ClearFlag()` should not be called with any second param that is a subflag of a multiflag, e.g. "relay" or "download," as that would leave the result in an invalid state corresponding to none of the existing NetPermissionFlags. Thanks to Vasil Dimov for noticing this.
ACKs for top commit:
theStack:
re-ACK 36fb036d25☕
vasild:
ACK 36fb036d25
hebasto:
ACK 36fb036d25, I have reviewed the code and it looks OK, I agree it can be merged.
kallewoof:
Code review ACK 36fb036d25
Tree-SHA512: 5fbc7ddbf31d06b35bf238f4d77ef311e6b6ef2e1bb9893f32f889c1a0f65774a3710dcb21d94317fe6166df9334a9f2d42630809e7fe8cbd797dd6f6fc49491
There are two issues:
1. Our I2P address not added to local addresses.
* `externalip=` is used with an IPv4 address (this sets automatically
`discover=0`)
* No `discover=1` is used
* `i2psam=` is used
* No `externalip=` is used for our I2P address
* `listenonion=1 torcontrol=` are used
In this case `AddLocal(LOCAL_MANUAL)` is used for our `.onion` address
and `AddLocal(LOCAL_BIND)` for our `.b32.i2p` address, the latter being
ignored due to `discover=0`.
2. Our I2P address removed from local addresses even if specified
with `externalip=` on I2P proxy restart.
* `externalip=` is used with our I2P address (this sets automatically
`discover=0`)
* No `discover=1` is used
* `i2psam=` is used
In this case, initially `externalip=` causes our I2P address to be added
with `AddLocal(LOCAL_MANUAL)` which overrides `discover=0` and works as
expected. However, if later the I2P proxy is shut down we do
`RemoveLocal()` in order to stop advertising our I2P address (since we
have lost I2P connectivity). When the I2P proxy is started and we
reconnect to it, restoring the I2P connectivity, we do
`AddLocal(LOCAL_BIND)` which does nothing due to `discover=0`.
To resolve those two issues, use `AddLocal(LOCAL_MANUAL)` for I2P which
is also what we do with Tor.
d66f283ac0 scripted-diff: Replace three dots with ellipsis in the UI strings (Hennadii Stepanov)
Pull request description:
This PR is split from #21463.
The change was suggested on [Transifex.com](https://www.transifex.com/bitcoin/bitcoin/), and it does not touch `LogPrint` and `LogPrintf` calls.
The only comment on #21463 [was](9030e4b5a6 (r597220100)):
> Mind that these messages also end up in the log. In principle the log is already UTF-8 (as are all strings and text in bitcoind). But, just noting, that it might make browsing the log a less pleasant experience on systems with misconfigured locale like some BSDs by default.
ACKs for top commit:
laanwj:
ACK d66f283ac0
Tree-SHA512: 5ab1cb3160f3f996f1ad7d7486662da3eb7f06a857f4a1874963ce10caed5b86b0ad6151b1b9ebeb2b8aa5f0c85efad3b768ea9cafe5db86f78f88912b756d1e
- Use `SanitizeString` when logging message errors to make sure that the
message type is sanitized.
- For the `MESSAGESTART` error don't inspect and log header details at
all: receiving invalid start bytes makes it likely that the packet isn't
even formatted as valid P2P message. Logging the four unexpected start
bytes should be enough.
- Update `p2p_invalid_messages.py` test to check this.
Issue reported by gmaxwell.
9096b13a47 net: remove unnecessary check of CNode::cs_vSend (Vasil Dimov)
Pull request description:
It is not possible to have a node in `CConnman::vNodesDisconnected` and
its reference count to be incremented - all `CNode::AddRef()` are done
either before the node is added to `CConnman::vNodes` or while holding
`CConnman::cs_vNodes` and the object being in `CConnman::vNodes`.
So, the object being in `CConnman::vNodesDisconnected` and its reference
count being zero means that it is not and will not start to be used by
other threads.
So, the lock of `CNode::cs_vSend` in `CConnman::DisconnectNodes()` will
always succeed and is not necessary.
Indeed all locks of `CNode::cs_vSend` are done either when the reference
count is >0 or under the protection of `CConnman::cs_vNodes` and the
node being in `CConnman::vNodes`.
ACKs for top commit:
MarcoFalke:
review ACK 9096b13a47🏧
jnewbery:
utACK 9096b13a47
Tree-SHA512: 910899cdcdc8934642eb0c40fcece8c3b01b7e20a0b023966b9d6972db6a885cb3a9a04e9562bae14d5833967e45e2ecb3687b94d495060c3da4b1f2afb0ac8f
8c8237a4a1 net, refactor: Fix style in CConnman::StopNodes (Hennadii Stepanov)
229ac1892d net: Combine two loops into one, and update comments (Hennadii Stepanov)
a3d090d110 net: Restrict period when cs_vNodes mutex is locked (Hennadii Stepanov)
Pull request description:
This PR restricts the period when the `cs_vNodes` mutex is locked, prevents the only case when `cs_vNodes` could be locked before the `::cs_main`.
This change makes the explicit locking of recursive mutexes in the explicit order redundant.
ACKs for top commit:
jnewbery:
utACK 8c8237a4a1
vasild:
ACK 8c8237a4a1
ajtowns:
utACK 8c8237a4a1 - logic seems sound
MarcoFalke:
review ACK 8c8237a4a1👢
Tree-SHA512: a8277924339622b188b12d260a100adf5d82781634cf974320cf6007341f946a7ff40351137c2f5369aed0d318f38aac2d32965c9b619432440d722a4e78bb73
It is not possible to have a node in `CConnman::vNodesDisconnected` and
its reference count to be incremented - all `CNode::AddRef()` are done
either before the node is added to `CConnman::vNodes` or while holding
`CConnman::cs_vNodes` and the object being in `CConnman::vNodes`.
So, the object being in `CConnman::vNodesDisconnected` and its reference
count being zero means that it is not and will not start to be used by
other threads.
So, the lock of `CNode::cs_vSend` in `CConnman::DisconnectNodes()` will
always succeed and is not necessary.
Indeed all locks of `CNode::cs_vSend` are done either when the reference
count is >0 or under the protection of `CConnman::cs_vNodes` and the
node being in `CConnman::vNodes`.
PF_NOBAN is a multi-flag that includes PF_DOWNLOAD, so the conditional
in CConnman::Bind() using a bitwise AND will return the same result
for both the "noban" status and the "download" status.
Example:
`PF_DOWNLOAD` is `0b1000000`
`PF_NOBAN` is `0b1010000`
This makes a check like `flags & PF_NOBAN` return `true` even if `flags`
is equal to `PF_DOWNLOAD`.
If `-whitebind=download@1.1.1.1:8765` is specified, then `1.1.1.1:8765`
should be added to the list of local addresses. We only want to avoid
adding to local addresses (that are advertised) a whitebind that has a
`noban@` flag.
As a result of a mis-check in `CConnman::Bind()` we would not have added
`1.1.1.1:8765` to the local addresses in the example above.
Co-authored-by: Vasil Dimov <vd@FreeBSD.org>
b2ee8b207d net: Deserialize hardcoded seeds from BIP155 blob (W. J. van der Laan)
9b29d5df7f contrib: Add explicit port numbers for testnet seeds (W. J. van der Laan)
2a257de113 contrib: Add a few TorV3 seed nodes (W. J. van der Laan)
06030f7a42 contrib: generate-seeds.py generates output in BIP155 format (W. J. van der Laan)
Pull request description:
Closes#20239 and mitigates my node's problem in #21351.
- Add a few hardcoded seeds for TorV3
- As the [bitcoin-seeder](https://github.com/sipa/bitcoin-seeder) doesn't collect TorV3 addresses yet, I have extracted these from my own node using [a script](https://gist.github.com/laanwj/b3d7b01ef61ce07c2eff0a72a6b90183) and added them manually. This is intended to be a temporary stop gap until 22.0's seeds update.
- Change hardcoded seeds to variable length BIP155 binary format.
- It is stored as a single serialized blob in a byte array, instead of pseudo-IPv6 address slots. This is more flexible and, assuming most of the list is IPv4, more compact.
- Only the (networkID, addr, port) subset (CService). Services and time are construed on the fly as before.
- Change input format for `nodes_*.txt`.
- Drop legacy `0xAABBCCDD` format for IPv4. It is never generated by `makeseeds.py`.
- Stop interpreting lack of port as default port, interpret it as 'no port', to accomodate I2P and other port-less protocols (not handled in this PR). An explicit port is always generated by `makeseeds.py` so in practice this makes no difference right now.
A follow-up to this PR could do the same for I2P.
ACKs for top commit:
jonatack:
ACK b2ee8b207d
Tree-SHA512: 11a6b54f9fb0192560f2bd7b218f798f86c1abe01d1bf37f734cb88b91848124beb2de801ca4e6f856e9946aea5dc3ee16b0dbb9863799e42eec1b239d40d59d
4783115fd4 net: add ifaddrs.h include (fanquake)
879215e665 build: check if -lsocket is required with *ifaddrs (fanquake)
87deac66aa rand: only try and use freeifaddrs if available (fanquake)
Pull request description:
Fixes#21485 by linking against `-lsocket` when it's required for using `*ifaddrs` functions.
ACKs for top commit:
laanwj:
Code review ACK 4783115fd4
hebasto:
ACK 4783115fd4, I have reviewed the code and it looks OK, I agree it can be merged.
Tree-SHA512: 4542e036e9b029de970eff8a9230fe45d9204bb22313d075f474295d49bdaf1f1cbb36c0c6e2fa8dbbcdba518d8d3a68a6116ce304b82414315f333baf9af0e4
40316a37cb test: add I2P test for a runaway SAM proxy (Vasil Dimov)
2d8ac77970 fuzz: add tests for the I2P Session public interface (Vasil Dimov)
9947e44de0 i2p: use pointers to Sock to accommodate mocking (Vasil Dimov)
82d360b5a8 net: change ConnectSocketDirectly() to take a Sock argument (Vasil Dimov)
b5861100f8 net: add connect() and getsockopt() wrappers to Sock (Vasil Dimov)
5a887d49b2 fuzz: avoid FuzzedSock::Recv() repeated errors with EAGAIN (Vasil Dimov)
3088f83d01 fuzz: extend FuzzedSock::Recv() to support MSG_PEEK (Vasil Dimov)
9b05c49ade fuzz: implement unimplemented FuzzedSock methods (Vasil Dimov)
Pull request description:
Change the networking code and the I2P code to be fully mockable and use `FuzzedSocket` to fuzz the I2P methods `Listen()`, `Accept()` and `Connect()`.
Add a mocked `Sock` implementation that returns a predefined data on reads and use it for a regression unit test for the bug fixed in https://github.com/bitcoin/bitcoin/pull/21407.
ACKs for top commit:
practicalswift:
Tested ACK 40316a37cb
MarcoFalke:
Concept ACK 40316a37cb
jonatack:
re-ACK 40316a37cb reviewed `git range-diff 01bb3afb 23c861d 40316a3` and the new unit test commit, debug built, ran unit tests, ran bitcoind with an I2P service and network operation with seven I2P peers (2 in, 5 out) is looking nominal
laanwj:
Code review ACK 40316a37cb
Tree-SHA512: 7fc4f129849e16e0c7e16662d9f4d35dfcc369bb31450ee369a2b97bdca95285533bee7787983e881e5a3d248f912afb42b4a2299d5860ace7129b0b19623cc8
0cca08a8ee Add unit test coverage for our onion peer eviction protection (Jon Atack)
caa21f586f Protect onion+localhost peers in ProtectEvictionCandidatesByRatio() (Jon Atack)
8f1a53eb02 Use EraseLastKElements() throughout SelectNodeToEvict() (Jon Atack)
8b1e156143 Add m_inbound_onion to AttemptToEvictConnection() (Jon Atack)
72e30e8e03 Add unit tests for ProtectEvictionCandidatesByRatio() (Jon Atack)
ca63b53ecd Use std::unordered_set instead of std::vector in IsEvicted() (Jon Atack)
41f84d5ecc Move peer eviction tests to a separate test file (Jon Atack)
f126cbd6de Extract ProtectEvictionCandidatesByRatio from SelectNodeToEvict (Jon Atack)
Pull request description:
Now that #19991 and #20210 have been merged, we can determine inbound onion peers using `CNode::m_inbound_onion` and add it to the localhost peers protection in `AttemptToEvictConnection`, which was added in #19670 to address issue #19500.
Update 28 February 2021: I've updated this to follow gmaxwell's suggestion in https://github.com/bitcoin/bitcoin/pull/20197#issuecomment-713865992.
This branch now protects up to 1/4 onion peers (connected via our tor control service), if any, sorted by longest uptime. If any (or all) onion slots remain after that operation, they are then allocated to protect localhost peers, or a minimum of 2 localhost peers in the case that no onion slots remain and 2 or more onion peers were protected, sorted as before by longest uptime.
This patch also adds test coverage for the longest uptime, localhost, and onion peer eviction protection logic to build on the welcome initial unit testing of #20477.
Suggest reviewing the commits that move code with `colorMoved = dimmed-zebra` and `colorMovedWs = allow-indentation-change`.
Closes#11537.
ACKs for top commit:
laanwj:
Code review ACK 0cca08a8ee
vasild:
ACK 0cca08a8ee
Tree-SHA512: 2f5a63f942acaae7882920fc61f0185dcd51da85e5b736df9d1fc72343726dd17da740e02f30fa5dc5eb3b2d8345707aed96031bec143d48a2497a610aa19abd
52dd40a9fe test: add missing netaddress include headers (Jon Atack)
6f09c0f6b5 util: add missing braces and apply clang format to SplitHostPort() (Jon Atack)
2875a764f7 util: add ParseUInt16(), use it in SplitHostPort() (Jon Atack)
6423c8175f p2p, refactor: pass and use uint16_t CService::port as uint16_t (Jon Atack)
Pull request description:
As noticed during review today in https://github.com/bitcoin/bitcoin/pull/20685#discussion_r584873708 of the upcoming I2P network support, `CService::port` is `uint16_t` but is passed around the codebase and into the ctors as `int`, which causes uneeded conversions and casts. We can avoid these (including in the incoming I2P code without further changes to it) by using ports with the correct type. The remaining conversions are pushed out to the user input boundaries where they can be range-checked and raise with user feedback in the next patch.
ACKs for top commit:
practicalswift:
cr ACK 52dd40a9fe: patch looks correct
MarcoFalke:
cr ACK 52dd40a9fe
vasild:
ACK 52dd40a9fe
Tree-SHA512: 203c1cab3189a206c55ecada77b9548b810281cdc533252b8e3330ae0606b467731c75f730ce9deb07cbaab66facf97e1ffd2051084ff9077cba6750366b0432
Now that we have a reliable way to detect inbound onion peers, this commit
updates our existing eviction protection of 1/4 localhost peers to instead
protect up to 1/4 onion peers (connected via our tor control service), sorted by
longest uptime. Any remaining slots of the 1/4 are then allocated to protect
localhost peers, or 2 localhost peers if no slots remain and 2 or more onion
peers are protected, sorted by longest uptime.
The goal is to avoid penalizing onion peers, due to their higher min ping times
relative to IPv4 and IPv6 peers, and improve our diversity of peer connections.
Thank you to Gregory Maxwell, Suhas Daftuar, Vasil Dimov and Pieter Wuille
for valuable review feedback that shaped the direction.
