The desired logic is for us to only open feeler connections after we have hit
the max count for outbound full relay connections. A short lived AddrFetch
connection (previously called oneshot) could cause ThreadOpenConnections to
miscount and mistakenly open a feeler instead of full relay.
fae656144e travis: Re-enable s390x (MarcoFalke)
Pull request description:
According to travis, the issue has been solved. Quote
> I would like to confirm that we have resolved this issue and most of our users are reported that this issue has been resolved on their end as well. Could you please re-check and see if that still exists for you?
ACKs for top commit:
theStack:
ACK fae656144e
Tree-SHA512: cf42f96d25474a9dcf0817a049e30e29714731d708f73c40a3042b0c70a71ff08f07dd96a89f0dcd5a50a63a355cf30b3511172a32b8af7d5a2e13ad222a4b49
fdf697fe75 ci: Increase CCACHE_SIZE in some builds on Travis (Hennadii Stepanov)
Pull request description:
This PR will decrease build time for the longest Travis builds.
Up to ~20 min improvement with warmed up cache is expected.
Top commit has no ACKs.
Tree-SHA512: ee3a22162d03537be11e60b53de043247f6a65e35e630e0807b758a846b7e05ef2059d18846644aafa3cd5dc7d3e3f56a8ccb94cc71b95227debc9201d3142a2
5962522fbc depends: bump native_cctools for fixed lto with external clang (Cory Fields)
00d1ba7aaa depends: enable lto support for Apple's ld64 (Cory Fields)
Pull request description:
This didn't work for a few reasons (various toolchain compatibility issues) the last time I tested it, but after the last round of bumps it works with no apparent issues.
Note that this does not _enable_ LTO by default in any way, only hooks up the machinery for ```-flto``` to work correctly when specified.
Lines were split for an easier rebase after #17919 is merged.
ACKs for top commit:
fanquake:
ACK 5962522fbc. The relevant option upstream is [here](https://github.com/tpoechtrager/cctools-port/blob/master/cctools/m4/llvm.m4#L4).
Tree-SHA512: df2775e74e7bc847e6cef94cb8457d503d6c9e2fdea861e51386fa6ed5a7ba688241db3685561ae1a32f66724c1b3801727252025f00c04b90a3bdc8a4f6f93b
a8865f8b72 [net processing] Tidy up Misbehaving() (John Newbery)
d15b3afb4c [net processing] Always supply debug message to Misbehaving() (John Newbery)
634144a1c2 [net processing] Fixup MaybeDiscourageAndDisconnect() style (John Newbery)
Pull request description:
This PR makes a few minor clean-ups to `Misbehaving()` in preparation to move it out of the cs_main lock.
There are very minor logging changes but otherwise no functional changes.
ACKs for top commit:
troygiorshev:
tACK a8865f8b72
jonatack:
ACK a8865f8
fjahr:
Code review ACK a8865f8b72
promag:
Code review ACK a8865f8b72.
Tree-SHA512: 98fb4f5f76399715545a1ea19290dcebfc8cb4eff72a1d3555dd3de6e184040bb8668c9651dab21db0dfd8e674e53a5977105ef76547146c9f6fa6b4b9d2ba59
fa5979d12f rpc: Avoid useless mempool query in gettxoutproof (MarcoFalke)
fa1f7f28cb rpc: Style fixups in gettxoutproof (MarcoFalke)
Pull request description:
`GetTransaction` implicitly and unconditionally asks the mempool global for a transaction. This is problematic for several reasons:
* `gettxoutproof` is for on-chain txs only and asking the mempool for on-chain txs is confusing and minimally wasteful
* Globals are confusing and make code harder to test with unit tests
Fix both issues by passing in an optional mempool. This also helps with #19556
ACKs for top commit:
hebasto:
re-ACK fa5979d12f
jnewbery:
utACK fa5979d12f
promag:
Code review ACK fa5979d12f.
Tree-SHA512: 048361b82abfcc40481181bd44f70cfc9e97d5d6356549df34bbe30b9de7a0a72d2207a3ad0279b21f06293509b284d8967f58ca7e716263a22b20aa4e7f9c54
7b3851e947 refactor: Drop unused CBufferedFile::Seek() (Hennadii Stepanov)
Pull request description:
ACKs for top commit:
practicalswift:
ACK 7b3851e947 -- deleted code is better than unused untested code:)
MarcoFalke:
ACK 7b3851e947, assuming that removing this should either be correct or result in a compile failure
jonasschnelli:
utACK 7b3851e947
promag:
Code review ACK 7b3851e947.
Tree-SHA512: 7bfd172aa4bbe349855c1303fd9cd58093d66833fefe46bd29081bfcca4ab434b84c6b84e76e94d06b8749a5abe1dc1e184f5189136cd1403d0e5bc25ad6d456
fa2ae0ac8d span: Add Span::empty() and use it in script/descriptor (MarcoFalke)
fa8a992589 Work around memory-aliasing in descriptor ParsePubkey (MarcoFalke)
Pull request description:
While this is not undefined behaviour, the memory aliasing trick is confusing when reading the code. Having `a.size()==0` and then access `a[0]` works in this particular case, but should probably be avoided to harden the code for the future.
ACKs for top commit:
theStack:
re-ACK fa2ae0ac8d
elichai:
ACK fa2ae0ac8d
jonatack:
ACK fa2ae0ac8d
Tree-SHA512: 0ec7b09eef45504973a195923cdf1aa8522117c8e2f69b453e5ce9aa8a7e327c71138518022c32d05133dc99cb861101ed0f60fa891814ee3e9dab3a6fa61a84
- Make const things const.
- Replace conditional return with assert.
- Don't log the peer's IP address.
- Log the name Misbehaving directly instead of relying on __func__.
Misbehaving() could optionally take a debug string for printing to the
log file. Make this mandatory and always provide the string.
A couple of additional minor changes:
- remove the unnecessary forward declaration of Misbehaving()
- don't include the nodeid or newline in the passed debug message.
Misbehaving() adds these itself.
655b195747 [net processing] Continue SendMessages processing if not disconnecting peer (John Newbery)
a49781e56d [net processing] Only call MaybeDiscourageAndDisconnect from SendMessages (John Newbery)
a1d5a428a2 [net processing] Fix bad indentation in SendMessages() (John Newbery)
1a1c23f8d4 [net processing] Change cs_main TRY_LOCK to LOCK in SendMessages() (John Newbery)
Pull request description:
The motivation for this PR is to reduce the scope of cs_main locking in misbehavior logic. It is the first set of commits from a larger branch to move the misbehavior data out of CNodeState and into a new struct that doesn't take cs_main.
There are some very minor behavior changes in this branch, such as:
- Not checking for discouragement/disconnect in `ProcessMessages()` (and instead relying on the following check in `SendMessages()`)
- Checking for discouragement/disconnect as the first action in `SendMessages()` (and not doing ping message sending first)
- Continuing through `SendMessages()` if `MaybeDiscourageAndDisconnect()` doesn't disconnect the peer (rather than dropping out of `SendMessages()`
ACKs for top commit:
jonatack:
re-ACK 655b195 per `git range-diff 505b4ed f54af5e 655b195`, code/commit messages review, a bit of code history, and debug build.
MarcoFalke:
ACK 655b195747 only some style-nits 🚁
promag:
Code review ACK 655b195747.
ariard:
Code Review ACK 655b195
Tree-SHA512: fd6d7bc6bb789f5fb7771fb6a45f61a8faba32af93b766554f562144f9631d15c9cc849a383e71743ef73e610b4ee14853666f6fbf08a3ae35176d48c76c65d3
ef3d4ce4c3 build: call AC_PATH_TOOL for dsymutil in macOS cross-compile (fanquake)
Pull request description:
While testing #19530 I noticed that we couldn't call [`dsymutil`](https://www.llvm.org/docs/CommandGuide/dsymutil.html) after LTO:
```bash
../libtool: line 10643: x86_64-apple-darwin16-dsymutil: command not found
```
This updates configure to call `AC_PATH_TOOL` so that we end up with the
full path to dsymutil, similar to `otool` and `install_name_tool`, ie:
`/bitcoin/depends/x86_64-apple-darwin16/share/../native/bin/x86_64-apple-darwin16-dsymutil`.
ACKs for top commit:
laanwj:
Code review ACK ef3d4ce4c3
theuni:
ACK ef3d4ce4c3.
Tree-SHA512: e4fa93e7f9f7945289143dfe2a6645ad8ee7f3bee0793412b3509901a30566d6f952e3b39e0e525a54f8dbd0c480f8da70fc6cb80b07800d11b0c6071fbb7466
9c69cfe4c5 Add <datadir>/settings.json persistent settings storage. (Russell Yanofsky)
eb682c5700 util: Add ReadSettings and WriteSettings functions (Russell Yanofsky)
Pull request description:
Persistent settings are used in followup PRs #15936 to unify gui settings between bitcoin-qt and bitcoind, and #15937 to add a load_on_startup flag to the loadwallet RPC and maintain a dynamic list of wallets that should be loaded on startup that also can be shared between bitcoind and bitcoin-qt.
ACKs for top commit:
MarcoFalke:
Approach re-ACK 9c69cfe4c5🌾
jnewbery:
utACK 9c69cfe4c5
Tree-SHA512: 39fcc6051717117c9141e934de1d0d3f739484be4685cdf97d54de967c8c816502b4fd0de12114433beaa5c5b7060c810fd8ae4e2b3ce7c371eb729ac01ba2e1
2aac093a3d test: Add test coverage for -networkactive option (Hennadii Stepanov)
3c58129b12 net: Log network activity status change unconditionally (Hennadii Stepanov)
62fe6aa87e net: Add -networkactive option (Hennadii Stepanov)
Pull request description:
Some Bitcoin Core activity is completely local (offline), e.g., reindexing.
The `setnetworkactive` RPC command is already present. This PR adds the corresponding command-line argument / config option, and allows to start the client with disabled p2p network by providing `-networkactive=0` or `-nonetworkactive`.
This was done while reviewing #16981.
ACKs for top commit:
MarcoFalke:
re-ACK 2aac093a3d🏠
LarryRuane:
ACK 2aac093a3d
Tree-SHA512: 446d791b46d7b556d7694df7b1f88cd4fbc09301fe4eaf036b45cb8166ed806156353cc03788a07b633d5887d5eee30a7c02a2d4307141c8ccc75e0a88145636
d416ae560e walletdb: Introduce WalletDatabase abstract class (Andrew Chow)
2179dbcbcd walletdb: Add BerkeleyDatabase::Open dummy function (Andrew Chow)
71d28e7cdc walletdb: Introduce AddRef and RemoveRef functions (Andrew Chow)
27b2766384 walletdb: Move BerkeleyDatabase::Flush(true) to Close() (Andrew Chow)
Pull request description:
A `WalletDatabase` abstract class is created from `BerkeleyDatabase` and is implemented by `BerkeleyDatabase`. First, to get to the point that this is possible, 4 functions need to be added to `BerkeleyDatabase`: `AddRef`, `RemoveRef`, `Open`, and `Close`.
First the increment and decrement of `mapFileUseCount` is refactored into separate functions `AddRef` and `RemoveRef`.
`Open` is introduced as a dummy function. This will raise an exception so that it always fails.
`Close` is refactored from `Flush`. The `shutdown` argument in `Flush` is removed and instead `Flush(true)` is now the `Close` function.
Split from #18971
Requires #19325
ACKs for top commit:
ryanofsky:
Code review ACK d416ae560e. Only changes since last review were rebasing after base PR #19334 merge, and adding cs_db lock in BerkeleyDatabase destructor, which should avoid races accessing env->m_databases and env->m_fileids
fjahr:
Code review ACK d416ae560e
meshcollider:
Code review & test run ACK d416ae560e
Tree-SHA512: 98d05ec093d7446c4488e2b0914584222a331e9a2f4d5be6af98e3f6d78fdd8e75526c12f91a8a52d4820c25bce02aa02aabe92d38bee7eb2fce07d0691b7b0d
The `setnetworkactive' RPC command is already present.
This new option allows to start the client with disabled p2p network
activity for testing or reindexing.
0a4f1422cd Further improve comments around recentRejects (Suhas Daftuar)
0e20cfedb7 Disconnect peers sending wtxidrelay message after VERACK (Suhas Daftuar)
cacd85209e test: Use wtxid relay generally in functional tests (Fabian Jahr)
8d8099e97a test: Add tests for wtxid tx relay in segwit test (Fabian Jahr)
9a5392fdf6 test: Update test framework p2p protocol version to 70016 (Fabian Jahr)
dd78d1d641 Rename AddInventoryKnown() to AddKnownTx() (Suhas Daftuar)
4eb515574e Make TX_WITNESS_STRIPPED its own rejection reason (Suhas Daftuar)
97141ca442 Delay getdata requests from peers using txid-based relay (Suhas Daftuar)
46d78d47de Add p2p message "wtxidrelay" (Suhas Daftuar)
2d282e0cba ignore non-wtxidrelay compliant invs (Anthony Towns)
ac88e2eb61 Add support for tx-relay via wtxid (Suhas Daftuar)
8e68fc246d Add wtxids to recentRejects instead of txids (Suhas Daftuar)
144c385820 Add wtxids of confirmed transactions to bloom filter (Suhas Daftuar)
85c78d54af Add wtxid-index to orphan map (Suhas Daftuar)
08b39955ec Add a wtxid-index to mapRelay (Suhas Daftuar)
60f0acda71 Just pass a hash to AddInventoryKnown (Suhas Daftuar)
c7eb6b4f1f Add wtxid to mempool unbroadcast tracking (Amiti Uttarwar)
2b4b90aa8f Add a wtxid-index to the mempool (Suhas Daftuar)
Pull request description:
Using txids (a transaction's hash, without witness) for transaction relay is problematic, post-segwit -- if a peer gives us a segwit transaction that fails policy checks, it could be because the txid associated with the transaction is definitely unacceptable to our node (regardless of the witness), or it could be that the transaction was malleated and with a different witness, the txid could be accepted to our mempool.
We have a bloom filter of recently rejected transactions, whose purpose is to help us avoid redownloading and revalidating transactions that fail to be accepted, but because of this potential for witness malleability to interfere with relay of valid transactions, we do not use the filter for segwit transactions. This issue is discussed at some length in #8279. The effect of this is that whenever a segwit transaction that fails policy checks is relayed, a node would download that transaction from every peer announcing it, because it has no way presently to cache failure. Historically this hasn't been a big problem, but if/when policy for accepting segwit transactions were to change (eg taproot, or any other change), we could expect older nodes talking to newer nodes to be wasting bandwidth because of this.
As discussed in that issue, switching to wtxid-based relay solves this problem -- by using an identifier for a transaction that commits to all the data in our relay protocol, we can be certain if a transaction that a peer is announcing is one that we've already tried to process, or if it's something new. This PR introduces support for wtxid-based relay with peers that support it (and remains backwards compatible with peers that use txids for relay, of course).
Apart from code correctness, one issue to be aware of is that by downloading from old and new peers alike, we should expect there to be some bandwidth wasted, because sometimes we might download the same transaction via txid-relay as well as wtxid-relay. The last commit in this PR implements a heuristic I want to analyze, which is to just delay relay from txid-relay peers by 2 seconds, if we have at least 1 wtxid-based peer. I've just started running a couple nodes with this heuristic so I can measure how well it works, but I'm open to other ideas for minimizing that issue. In the long run, I think this will be essentially a non-issue, so I don't think it's too big a concern, we just need to bite the bullet and deal with it during upgrade.
Finally, this proposal would need a simple BIP describing the changes, which I haven't yet drafted. However, review and testing of this code in the interim would be welcome.
To do items:
- [x] Write BIP explaining the spec here (1 new p2p message for negotiating wtxid-based relay, along with a new INV type)
- [ ] Measure and evaluate a heuristic for minimizing how often a node downloads the same transaction twice, when connected to old and new nodes.
ACKs for top commit:
naumenkogs:
utACK 0a4f1422cd
laanwj:
utACK 0a4f1422cd
Tree-SHA512: d8eb8f0688cf0cbe9507bf738e143edab1f595551fdfeddc2b6734686ea26e7f156b6bfde38bad8bbbe8bec1857c7223e1687f8f018de7463dde8ecaa8f450df
fa56eda58e log: Avoid treating remote misbehvior as local system error (MarcoFalke)
fa492895b5 refactor: Switch ValidationState mode to C++11 enum class (MarcoFalke)
Pull request description:
When logging failures of `CheckBlockHeader` (high-hash), they are always logged as system error. This is problematic for several reasons:
* Submitting a blockheader that fails `CheckBlockHeader` over RPC will result in a debug log line that starts with `ERROR`. Proper behaviour should be to log not anything and instead only return the failure reason to the RPC user. This pull does not fix this issue entirely, but is a good first step in the right direction.
* A misbehaving peer that sends us an invalid block header that fails `CheckBlockHeader` will result in a debug log line that starts with `ERROR`. Proper behavior should be to log the remote peer misbehavior if logging for that category was enabled. This pull fixes this issue for `CheckBlockHeader` and other functions can be adjusted as well if needed in follow-ups. This should be a good first step in the right direction.
ACKs for top commit:
practicalswift:
re-ACK fa56eda58e
Tree-SHA512: 9793191f5cb57bdff7c93926e94877e8ca2ef89dcebcf9eb155899c733961839ec7c3f9b9f001dc082ada4234fe6e75f6df431301678d6822325840771166d77
1554b54d47 Static asserts for consistency of fee defaults. (Daniel Kraft)
Pull request description:
This adds `static_assert`'s that ensure that the default values given for fee levels in the wallet (minimum fee and incremental feerate increase) are at least as high as the corresponding levels configured in the core node policy. Since the core policy values are enforced by the network, it makes sense for the wallet to be conservative and above (or at least not below) this.
ACKs for top commit:
laanwj:
code review ACK 1554b54d47, these assumptions seem straightforward
Tree-SHA512: 50e5adf082f467062334377f82a3ee75bcfd436afc65bd0eb33c8d0549d6d90fd1f48c31f60cabe523eb59be9efa8ae0879e9e09cd51ca9c1bd466631ce03cf4
2a701a1c42 build: pass -fcommon when building genisoimage (fanquake)
Pull request description:
Starting with the 10.1 release, GCC [defaults to -fno-common](https://gcc.gnu.org/gcc-10/porting_to.html). This causes
linking issues when building genisoimage:
```bash
[ 98%] Building C object genisoimage/CMakeFiles/genisoimage.dir/checksum.o
[100%] Linking C executable genisoimage
/usr/bin/ld: CMakeFiles/genisoimage.dir/apple.o:(.bss+0x0): multiple definition of `outfile'; CMakeFiles/genisoimage.dir/genisoimage.o:(.bss+0x0): first defined here
/usr/bin/ld: CMakeFiles/genisoimage.dir/boot.o:(.bss+0x0): multiple definition of `outfile'; CMakeFiles/genisoimage.dir/genisoimage.o:(.bss+0x0): first defined here
/usr/bin/ld: CMakeFiles/genisoimage.dir/desktop.o:(.bss+0x0): multiple definition of `outfile'; CMakeFiles/genisoimage.dir/genisoimage.o:(.bss+0x0): first defined here
/usr/bin/ld: CMakeFiles/genisoimage.dir/dvd_file.o:(.bss+0x0): multiple definition of `outfile'; CMakeFiles/genisoimage.dir/genisoimage.o:(.bss+0x0): first defined here
```
Rather than patching genisoimage further, just pass -fcommon to preserve
the legacy GCC behaviour.
Noticed [while testing #19530](https://github.com/bitcoin/bitcoin/pull/19530#issuecomment-659802512).
ACKs for top commit:
laanwj:
ACK 2a701a1c42
hebasto:
ACK 2a701a1c42, tested on Fedora 32 (x86_64, GCC 10.1.1):
Tree-SHA512: 0e6dd1b4c7c3f5b6997616da27a7ea54f757c81677766ee6813c776356527787a32b959f834e699fee9798553b13bcb142469f442c5e7a04f810f2c06e3a9505
While testing #19530 I noticed that we couldn't call dsymutil after LTO:
```bash
../libtool: line 10643: x86_64-apple-darwin16-dsymutil: command not found
```
This updates configure to call `AC_PATH_TOOL` so that we end up with the
full path to dsymutil, similar to `otool` and `install_name_tool`, ie:
`/bitcoin/depends/x86_64-apple-darwin16/share/../native/bin/x86_64-apple-darwin16-otool`.
c8992e8959 test: Fix fuzzer compilation on macOS fixes#19557 (freenancial)
Pull request description:
fixes#19557
Before the fix:
```
➜ bitcoin git:(fix-fuzzer-macos) make
Making all in src
CXX test/fuzz/addition_overflow-addition_overflow.o
In file included from test/fuzz/addition_overflow.cpp:7:
./test/fuzz/util.h:335:13: error: no matching function for call to 'AdditionOverflow'
if (AdditionOverflow((uint64_t)fuzzed_file->m_offset, random_bytes.size())) {
^~~~~~~~~~~~~~~~
./test/fuzz/util.h:201:16: note: candidate template ignored: deduced conflicting types for parameter 'T' ('unsigned long long' vs. 'unsigned long')
NODISCARD bool AdditionOverflow(const T i, const T j) noexcept
^
./test/fuzz/util.h:346:13: error: no matching function for call to 'AdditionOverflow'
if (AdditionOverflow(fuzzed_file->m_offset, n)) {
^~~~~~~~~~~~~~~~
./test/fuzz/util.h:201:16: note: candidate template ignored: deduced conflicting types for parameter 'T' ('long long' vs. 'long')
NODISCARD bool AdditionOverflow(const T i, const T j) noexcept
^
```
After the fix:
```
➜ bitcoin git:(fix-fuzzer-macos) ./configure --enable-fuzz --with-sanitizers=fuzzer,address,undefined CC=/usr/local/opt/llvm/bin/clang CXX=/usr/local/opt/llvm/bin/clang++ --disable-asm && make clean && make -j5
...
...
CXXLD test/fuzz/uint256_deserialize
Making all in doc/man
make[1]: Nothing to be done for `all'.
make[1]: Nothing to be done for `all-am'.
```
ACKs for top commit:
fanquake:
ACK c8992e8959 - tested that compiling works on macOS.
MarcoFalke:
review ACK c8992e8959
Tree-SHA512: 965cdc61b30db0e2209c91b29f0d42de927a9a5b85e1e70f22d1452e0955f876726c7a8c1d1a5f448f12bf24eec3000802071cd4ae28d8605343fd43d174ca84
c0f09c2c9d fuzz: add missing overrides to signature_checker (Jon Atack)
Pull request description:
These functions in `fuzz/signature_checker.cpp` override virtual member functions and should be marked `override` instead of `virtual`, which is for introducing a new virtual function. The overridden virtual functions are in `script/interpreter.h:151/156/161`.
Also, per MarcoFalke suggestion, add missing parentheses in `fuzz/scriptnum_ops.cpp` and remove useless `unsigned int >= 0` conditional in `fuzz/script.cpp`.
These changes fix 5 compile warnings in gcc 10 and 3 in clang 11/12.
ACKs for top commit:
vasild:
ACK c0f09c2
MarcoFalke:
review ACK c0f09c2c9d
Tree-SHA512: 76ce73ec577c1f23cf8646c31d44dcd6c6303732c47187d041a8921d0d24a50163989a375352ebc221abf2ac337bc0902149be46b6f9eebc071d2f364c407f71
d0ea9bab28 walletdb: Don't remove database transaction logs and instead error (Andrew Chow)
Pull request description:
Instead of removing the database transaction logs and retrying the
wallet loading, just return an error message to the user. Additionally,
speciically for DB_RUNRECOVERY, notify the user that this could be due
to different BDB versions.
Kind of implements the suggestion from https://github.com/bitcoin/bitcoin/pull/18870#discussion_r421647964
ACKs for top commit:
Sjors:
re-utACK d0ea9bab28
ryanofsky:
Code review ACK d0ea9bab28. Only changes since last review are rebase and expanding error and commit messages.
Tree-SHA512: f6e67dc70f58188742a5c8af7cdc63a2b58779aa0d26ae7f1e75805a239f1a342433860e5a238d6577fae5ab04b9d15e7f11c55b867065dfd13781a6a62e4958
and also
- add missing parentheses in fuzz/scriptnum_ops.cpp
- remove useless unsigned int conditional in fuzz/script.cpp
These changes fix 5 compile warnings in gcc 10.
ec4c6a17e8 scripted-diff: replace MAX_BLOCKS_ONLY_CONNECTIONS with MAX_BLOCK_RELAY_ONLY_CONNECTIONS (glowang)
Pull request description:
We have two different concepts that have similar names: `-blocksonly` and `block-relay-only`, and the similarity of names could lead to confusion. `-blocksonly` disables all local receiving & relaying of transactions (with a few exceptions), while `block-relay-only`means that bitcoind will make 2 additional outbound connections that are only used for block relay.
In net.h and init.cpp, `MAX_BLOCKS_ONLY_CONNECTIONS` is used to represent the maximum number of `block-relay-only` outbound peers, which is 2. But this name sounds ambiguous, and I proposed a better name, `MAX_BLOCK_RELAY_ONLY_CONNECTION`.
ACKs for top commit:
jnewbery:
ACK ec4c6a17e8
Tree-SHA512: cfa592a7ff936f14d10cfc1e926a51b82bc0feaf104885a41ca8111b906cb3d1ec5536bab143a3cfca70aa49e9575c6995941eb6d3d7f4018d4535712342f155
