3388e523a1 Rework receive buffer pushback (Pieter Wuille)
Pull request description:
See https://github.com/ElementsProject/elements/issues/1233. There, it has been observed that if both sides of a P2P connection have a significant amount of data to send, a stall can occur, where both try to drain their own send queue before trying to receive. The same issue seems to apply to the current Bitcoin Core codebase, though I don't know whether it's a frequent issue for us.
The core issue is that whenever our optimistic send fails to fully send a message, we do subsequently not even select() for receiving; if it then turns out that sending is not possible either, no progress is made at all. To address this, the solution used in this PR is to still select() for both sending and receiving when an optimistic send fails, but skip receiving if sending succeeded, and (still) doesn't fully drain the send queue.
This is a significant reduction in how aggressive the "receive pushback" mechanism is, because now it will only mildly push back while sending progress is made; if the other side stops receiving entirely, the pushback disappears. I don't think that's a serious problem though:
* We still have a pushback mechanism at the application buffer level (when the application receive buffer overflows, receiving is paused until messages in the buffer get processed; waiting on our own net_processing thread, not on the remote party).
* There are cases where the existing mechanism is too aggressive; e.g. when the send queue is non-empty, but tiny, and can be sent with a single send() call. In that case, I think we'd prefer to still receive within the same processing loop of the network thread.
ACKs for top commit:
ajtowns:
ACK 3388e523a1
naumenkogs:
ACK 3388e523a1
mzumsande:
Tested ACK 3388e523a1
Tree-SHA512: 28960feb3cd2ff3dfb39622510da62472612f88165ea98fc9fb844bfcb8fa3ed3633f83e7bd72bdbbbd37993ef10181b2e1b34836ebb8f0d83fd1c558921ec17
1b52d16d07 p2p: network-specific management of outbound connections (Martin Zumsande)
65cff00cee test: Add test for outbound protection by network (Martin Zumsande)
034f61f83b p2p: Protect extra full outbound peers by network (Martin Zumsande)
654d9bc276 p2p: Introduce data struct to track connection counts by network (Amiti Uttarwar)
Pull request description:
This is joint work with mzumsande.
This is a proposal to diversify outbound connections with respect to reachable networks. The existing logic evaluates peers for connection based purely on the frequency of available addresses in `AddrMan`. This PR adds logic to automatically connect to alternate reachable networks and adds eviction logic that protects one existing connection to each network.
For instance, if `AddrMan` is populated primarily with IPv4 and IPv6 addresses and only a handful of onion addresses, it is likely that we won't establish any automatic outbound connections to Tor, even if we're capable of doing so. For smaller networks like CJDNS, this is even more of an issue and often requires adding manual peers to ensure regularly being connected to the network.
Connecting to multiple networks improves resistance to eclipse attacks for individual nodes. It also benefits the entire p2p network by increasing partition resistance and privacy in general.
The automatic connections to alternate networks is done defensively, by first filling all outbound slots with random addresses (as in the status quo) and then adding additional peers from reachable networks the node is currently not connected to. This approach ensures that outbound slots are not left unfilled while attempting to connect to a network that may be unavailable due to a technical issue or misconfiguration that bitcoind cannot detect.
Once an additional peer is added and we have one more outbound connection than we want, outbound eviction ensures that peers are protected if they are the only ones for their network.
Manual connections are also taken into account: If a user already establishes manual connections to a trusted peer from a network, there is no longer a need to make extra efforts to ensure we also have an automatic connection to it (although this may of course happen by random selection).
ACKs for top commit:
naumenkogs:
ACK 1b52d16d07
vasild:
ACK 1b52d16d07
Tree-SHA512: 5616c038a5fbb868d4c46c5963cfd53e4599feee25db04b0e18da426d77d22e0994dc4e1da0b810f5b457f424ebbed3db1704f371aa6cad002b3565b20170ec0
Diversify outbound connections with respect to
networks: Every ~5 minutes, try to add an extra connection
to a reachable network which we currently don't have a connection to.
This is done defensively - only try management with respect to networks
after all existing outbound slots are filled.
The resulting situation with an extra outbound peer will be handled
by the extra outbound eviction logic, which protects peers from
eviction if they are the only ones for their network.
Co-authored-by: Amiti Uttarwar <amiti@uttarwar.org>
If a peer is the only one of its network, protect it from eviction.
This improves the diversity of outbound connections with respect to
reachable networks.
Co-authored-by: Amiti Uttarwar <amiti@uttarwar.org>
Connman uses this new map to keep a count of active OUTBOUND_FULL_RELAY and
MANUAL connections. Unused until next commit.
Co-authored-by: Martin Zumsande <mzumsande@gmail.com>
e7cf8657e1 test: add unit test for local address advertising (Martin Zumsande)
f4754b9dfb net: restrict self-advertisements with privacy networks (Martin Zumsande)
e4d541c7cf net, refactor: pass reference for peer address in GetReachabilityFrom (Martin Zumsande)
62d73f5370 net, refactor: pass CNode instead of CNetAddr to GetLocalAddress (Martin Zumsande)
Pull request description:
The current logic for self-advertisements works such that we detect as many local addresses as we can, and then, using the scoring matrix from `CNetAddr::GetReachabilityFrom()`, self-advertise with the address that fits best to our peer.
It is in general not hard for our peers to distinguish our self-advertisements from other addrs we send them, because we self-advertise every ~24h and because the first addr we send over a connection is likely our self-advertisement.
`GetReachabilityFrom()` currently only takes into account actual reachability, but not whether we'd _want_ to announce our identity for one network to peers from other networks, which is not straightforward in connection with privacy networks.
While the general approach is to prefer self-advertising with the address for the network our peer is on, there are several special situations in which we don't have one, and as a result could allow self-advertise other local addresses, for example:
A) We run i2p and clearnet, use `-i2pacceptincoming=0` (so we have no local i2p address), and we have a local ipv4 address. In this case, we'd advertise the ipv4 address to our outbound i2p peers.
B) Our `-discover` logic cannot detect any local clearnet addresses in our network environment, but we are actually reachable over clearnet. If we ran bitcoind clearnet-only, we'd always advertise the address our peer sees us with instead, and could get inbound peers this way. Now, if we also have an onion service running (but aren't using tor as a proxy for clearnet connections), we could advertise our onion address to clearnet peers, so that they would be able to connect our clearnet and onion identities.
This PR tries to avoid these situations by
1.) never advertising our local Tor or I2P address to peers from other networks.
2.) never advertising local addresses from non-anonymity networks to peers from Tor or I2P
Note that this affects only our own self-advertisements, the rules to forward other people's addrs are not changed.
[Edit] after Initial [discussion](https://github.com/bitcoin/bitcoin/pull/27411#issuecomment-1497176155): CJDNS is not being treated like Tor and I2P at least for now, because it has different privacy properties and for the practical reason that it has still very few bitcoin nodes.
ACKs for top commit:
achow101:
ACK e7cf8657e1
vasild:
ACK e7cf8657e1
luke-jr:
utACK e7cf8657e1
Tree-SHA512: 3db8415dea6f82223d11a23bd6cbb3b8cf68831321280e926034a1f110cbe22562570013925f6fa20d8f08e41d0202fd69c733d9f16217318a660d2a1a21b795
5fa4055452 net: do not `break` when `addr` is not from a distinct network group (brunoerg)
Pull request description:
When the address is from a network group we already caught,
do a `continue` and try to find another address until conditions
are met or we reach the limit (`nTries`).
ACKs for top commit:
amitiuttarwar:
utACK 5fa4055452
achow101:
ACK 5fa4055452
mzumsande:
utACK 5fa4055452
Tree-SHA512: 225bb6df450b46960db934983c583e862d1a17bacfc46d3657a0eb25a0204e106e8cd18de36764e210e0a92489ab4b5773437e4a641c9b455bde74ff8a041787
fa38d86235 Use only Span{} constructor for byte-like types where possible (MarcoFalke)
fa257bc831 util: Allow std::byte and char Span serialization (MarcoFalke)
Pull request description:
Seems odd to require developers to cast all byte-like spans passed to serialization to `unsigned char`-spans. Fix that by passing and accepting byte-like spans as-is. Finally, add tests and update the code to use just `Span` where possible.
ACKs for top commit:
sipa:
utACK fa38d86235
achow101:
ACK fa38d86235
ryanofsky:
Code review ACK fa38d86235. This looks great. The second commit really removes a lot of boilerplate and shows why the first commit is useful.
Tree-SHA512: 788592d9ff515c3ebe73d48f9ecbb8d239f5b985af86f09974e508cafb0ca6d73a959350295246b4dfb496149bc56330a0b5d659fc434ba6723dbaba0b7a49e5
32e2ffc393 Remove the syscall sandbox (fanquake)
Pull request description:
After initially being merged in #20487, it's no-longer clear that an internal syscall sandboxing mechanism is something that Bitcoin Core should have/maintain, especially when compared to better maintained/supported alterantives, i.e [firejail](https://github.com/netblue30/firejail).
There is more related discussion in #24771.
Note that given where it's used, the sandbox also gets dragged into the kernel.
If it's removed, this should not require any sort of deprecation, as this was only ever an opt-in, experimental feature.
Closes #24771.
ACKs for top commit:
davidgumberg:
crACK 32e2ffc393
achow101:
ACK 32e2ffc393
dergoegge:
ACK 32e2ffc393
Tree-SHA512: 8cf71c5623bb642cb515531d4a2545d806e503b9d57bfc15a996597632b06103d60d985fd7f843a3c1da6528bc38d0298d6b8bcf0be6f851795a8040d71faf16
30778124b8 net: Give seednodes time before falling back to fixed seeds (Martin Zumsande)
Pull request description:
`-seednode` is an alternative bootstrap mechanism - when choosing it, we make a `AddrFetch` connection to the specified peer, gather addresses from them, and then disconnect. Presumably, if users specify a seednode they prefer addresses from that node over fixed seeds.
However, when disabling dns seeds and specifiying `-seednode`, `CConnman::ProcessAddrFetch()` immediately removes the entry from `m_addr_fetches` (before the seednode could give us addresses) - and once `m_addr_fetches` is empty, `ThreadOpenConnections` will add fixed seeds, resulting in a "race" between the fixed seeds and seednodes filling up AddrMan.
This PR suggests to check for any provided `-seednode` arg instead of using the size of `m_addr_fetches`, thus delaying the querying of fixed seeds for 1 minute when specifying any seednode (as we already do for `addnode` peers).
That way, we actually give the seednodes a chance for to provide us with addresses before falling back to fixed seeds.
This can be tested with `bitcoind -debug=net -dnsseed=0 -seednode=(...)` on a node without `peers.dat` and observing the debug log.
ACKs for top commit:
ajtowns:
utACK 30778124b8
achow101:
ACK 30778124b8
dergoegge:
Code review ACK 30778124b8
sr-gi:
ACK [3077812](30778124b8) with a tiny nit, feel free to ignore it
Tree-SHA512: 96446eb34c0805f10ee158a00a3001a07029e795ac40ad5638228d426e30e9bb836c64ac05d145f2f9ab23ec5a528f3a416e3d52ecfdfb0b813bd4b1ebab3c01
After initially being merged in #20487, it's no-longer clear that an
internal syscall sandboxing mechanism is something that Bitcoin Core
should have/maintain, especially when compared to better
maintained/supported alterantives, i.e firejail.
Note that given where it's used, the sandbox also gets dragged into the
kernel.
There is some related discussion in #24771.
This should not require any sort of deprecation, as this was only ever
an opt-in, experimental feature.
Closes #24771.
When the address is from a network group we already caught,
do a `continue` and try to find another address until conditions
are met or we reach the limit (`nTries`).
11bb31c1c4 p2p: "skip netgroup diversity of new connections for tor/i2p/cjdns" follow-up (Jon Atack)
Pull request description:
In #27374 the role of the `setConnected` data structure in `CConnman::ThreadOpenConnections` changed from the set of outbound peer netgroups to those of outbound IPv4/6 peers only.
In accordance with the changed semantics, this pull fixes a code comment regarding feeler connections and updates the naming of `setConnected` to `outbound_ipv46_peer_netgroups`.
Addresses https://github.com/bitcoin/bitcoin/pull/27374#discussion_r1167172725.
ACKs for top commit:
mzumsande:
Code Review ACK 11bb31c1c4
vasild:
ACK 11bb31c1c4
ryanofsky:
Code review ACK 11bb31c1c4
Tree-SHA512: df9151a6cce53c279e549683a9f30fdc23d513dc664cfee1cf0eb8ec80b2848d32c80a92cc0a9f47d967f305864975ffb339fe0eaa80bc3bef1b28406419eb96
Stop advertising
1) our i2p/onion address to peers from other networks
2) Local addresses of non-privacy networks to i2p/onion peers
Doing so could lead to fingerprinting ourselves.
Co-authored-by: Vasil Dimov <vd@FreeBSD.org>
The address of the peer always exists (because addr is a member of
CNode), so it was not possible to pass a nullptr before.
Also remove NET_UNKNOWN, which is unused now.
be55f545d5 move-only: Extract common/args and common/config.cpp from util/system (TheCharlatan)
Pull request description:
This pull request is part of the `libbitcoinkernel` project https://github.com/bitcoin/bitcoin/issues/24303https://github.com/bitcoin/bitcoin/projects/18 and more specifically its "Step 2: Decouple most non-consensus code from libbitcoinkernel". It is part of a series of patches splitting up the `util/system` files. Its preceding pull request is https://github.com/bitcoin/bitcoin/pull/27254.
The pull request contains an extraction of ArgsManager related functions from util/system into their own common/ file.
The background of this commit is an ongoing effort to decouple the libbitcoinkernel library from the ArgsManager. The ArgsManager belongs into the common library, since the kernel library should not depend on it. See [doc/design/libraries.md](https://github.com/bitcoin/bitcoin/blob/master/doc/design/libraries.md) for more information on this rationale.
ACKs for top commit:
MarcoFalke:
re-ACK be55f545d5🚲
ryanofsky:
Code review ACK be55f545d5. Just small cleanups since the last review.
hebasto:
ACK be55f545d5, I have reviewed the code and it looks OK, I agree it can be merged.
Tree-SHA512: 90eb03334af0155b823030b4f2ecf286d35058d700ee2ddbbaa445be19e31eb0fe982656f35bd14ecee3ad2c3d0db3746855cb8f3777eff7253713e42873e111
0076bed45e logging: log ASN when using `-asmap` (brunoerg)
9836c76ae0 net: add `GetMappedAS` in `CConnman` (brunoerg)
Pull request description:
When using `-asmap`, you can check the ASN assigned to the peers only with the RPC command `getpeerinfo` (check `mapped_as` field), however, it's not possible to check it in logs (e.g. see in logs the ASN of the peers when a new outbound peer has been connected). This PR includes the peers' ASN in debug output when using `-asmap`.
Obs: Open this primarily to chase some Concept ACK, I've been using this on my node to facilitate to track the peers' ASN especially when reading the logs.
ACKs for top commit:
Sjors:
tACK 0076bed45e
jamesob:
ACK 0076bed45e ([`jamesob/ackr/27412.1.brunoerg.logging_net_add_asn_from`](https://github.com/jamesob/bitcoin/tree/ackr/27412.1.brunoerg.logging_net_add_asn_from))
achow101:
ACK 0076bed45e
Tree-SHA512: c19cd11e8ab49962021f390459aadf6d33d221ae9a2c3df331a25d6865a8df470e2c8828f6e5219b8a887d6ab5b3450d34be9e26c00cca4d223b4ca64d51111b
This is an extraction of ArgsManager related functions from util/system
into their own common file.
Config file related functions are moved to common/config.cpp.
The background of this commit is an ongoing effort to decouple the
libbitcoinkernel library from the ArgsManager. The ArgsManager belongs
into the common library, since the kernel library should not depend on
it. See doc/design/libraries.md for more information on this rationale.
In PR 27374, the semantics of the `setConnected` data structure in
CConnman::ThreadOpenConnections changed from the set of outbound peer
netgroups to those of outbound IPv4/6 peers only.
This commit updates a code comment in this regard about feeler connections and
updates the naming of `setConnected` to `outbound_ipv46_peer_netgroups` to
reflect its new role.
00e9b97f37 refactor: Move fs.* to util/fs.* (TheCharlatan)
106b46d9d2 Add missing fs.h includes (TheCharlatan)
b202b3dd63 Add missing cstddef include in assumptions.h (TheCharlatan)
18fb36367a refactor: Extract util/fs_helpers from util/system (Ben Woosley)
Pull request description:
This pull request is part of the `libbitcoinkernel` project https://github.com/bitcoin/bitcoin/issues/24303https://github.com/bitcoin/bitcoin/projects/18 and more specifically its "Step 2: Decouple most non-consensus code from libbitcoinkernel". This commit was originally authored by empact and is taken from its parent PR #25152.
#### Context
There is an ongoing effort to decouple the `ArgsManager` used for command line parsing user-provided arguments from the libbitcoinkernel library (https://github.com/bitcoin/bitcoin/pull/25290, https://github.com/bitcoin/bitcoin/pull/25487, https://github.com/bitcoin/bitcoin/pull/25527, https://github.com/bitcoin/bitcoin/pull/25862, https://github.com/bitcoin/bitcoin/pull/26177, and https://github.com/bitcoin/bitcoin/pull/27125). The `ArgsManager` is defined in `system.h`. A similar pull request extracting functionality from `system.h` has been merged in https://github.com/bitcoin/bitcoin/pull/27238.
#### Changes
Next to providing better code organization, this PR removes some reliance of the tree of libbitcoinkernel header includes on `system.h` (and thus the `ArgsManager` definition) by moving filesystem related functions out of the `system.*` files.
There is already a pair of `fs.h` / `fs.cpp` in the top-level `src/` directory. They were not combined with the files introduced here, to keep the patch cleaner and more importantly because they are often included without the utility functions. The new files are therefore named `fs_helpers` and the existing `fs` files are moved into the util directory.
Further commits splitting more functionality out of `system.h` are still in #25152 and will be submitted in separate PRs once this PR has been processed.
ACKs for top commit:
hebasto:
ACK 00e9b97f37
Tree-SHA512: 31422f148d14ba3c843b99b1550a6fd77c77f350905ca324f93d4f97b652246bc58fa9696c64d1201979cf88733e40be02d262739bb7d417cf22bf506fdb7666
The fs.* files are already part of the libbitcoin_util library. With the
introduction of the fs_helpers.* it makes sense to move fs.* into the
util/ directory as well.
Previously, we would make connections to peer from the netgroups to which
our MANUAL outbound connections belong.
However, they should be seen as regular connections from Addrman when it comes to netgroup diversity check, since the same rationale can be applied.
Note, this has nothing to do with how we connect to MANUAL connections:
we connect to them unconditionally.
error is a low-level function with a sole dependency on LogPrintf, which
is defined in logging.h
The background of this commit is an ongoing effort to decouple the
libbitcoinkernel library from the ArgsManager defined in system.h.
Moving the function out of system.h allows including it from a separate
source file without including the ArgsManager definitions from system.h.
3c1de032de i2p: use consistent number of tunnels with i2pd and Java I2P (Vasil Dimov)
801b405f85 i2p: lower the number of tunnels for transient sessions (Vasil Dimov)
b906b64eb7 i2p: reuse created I2P sessions if not used (Vasil Dimov)
Pull request description:
* Reuse an I2P transient session instead of discarding it if we failed to connect to the desired peer. This means we never used the generated address (destination), whose creation is not cheap. This does not mean that we will use the same address for more than one peer.
* Lower the number of tunnels for transient sessions.
* Explicitly specify the number of tunnels for persistent sessions instead of relying on the defaults which differ between I2P routers. This way we get consistent behavior with all routers.
Alleviates: https://github.com/bitcoin/bitcoin/issues/26754
(I have not tested this with i2pd, yet)
ACKs for top commit:
jonatack:
ACK 3c1de032de
mzumsande:
Light ACK 3c1de032de
Tree-SHA512: 477b4b9a5755e6a9a46bc0f7b268fa419dff4414e25445c750ae913f7552d9e2313f2aca4e3b70067b8390c2d0c2d68ec459f331765e939fc84139e454031cd4
2555a3950f p2p: ProcessAddrFetch(-seednode) is unnecessary if -connect is specified (Dhruv Mehta)
Pull request description:
If the user runs: `bitcoind -connect=X -seednode=Y`, I _think_ it is safe to ignore `-seednode`. A more populated `addrman` (via `getaddr` calls to peers in `-seednode`) is not useful in this configuration: `addrman` entries are used to initiate new outbound connections when slots are open, or to open feeler connections and keep `addrman` from getting stale. This is all done in a part of `ThreadOpenConnections` (below [this line](https://github.com/bitcoin/bitcoin/blob/master/src/net.cpp#L1803)) which is never executed when `-connect` is supplied. With `-connect`, `ThreadOpenConnections` will run [this loop](https://github.com/bitcoin/bitcoin/blob/master/src/net.cpp#L1785) and exit thread execution when interrupted.
Reviewers may also find it relevant that when `-connect` is used, we [soft disable](https://github.com/bitcoin/bitcoin/blob/master/src/init.cpp#L800) `-dnsseed` in init.cpp perhaps for the same reason i.e. seeding is not useful with `-connect`.
Running `ProcessAddrFetch` does not seem to have downside except developer confusion AFAICT. I was confused by this and felt it might affect other new bitcoiners too. If there is strong preference to not remove the line, I'd also be happy to just leave a comment there mentioning `ADDR_FETCH`/`-seednode` is irrelevant when used with `-connect`.
If this change is accepted, the node will still make `getaddr` calls to peers in `-connect` and expand `addrman`. However, disabling those `getaddr` calls would leak information about the node's configuration.
ACKs for top commit:
mzumsande:
Code Review ACK 2555a3950f
achow101:
ACK 2555a3950f
vasild:
ACK 2555a3950f
Tree-SHA512: 9187a0cff58db8edeca7e15379b1c121e7ebe8c38fb82f69e3dae8846ee94c92a329d79025e0f023c7579b2d86e7dbf756e4e30e90a72236bfcd2c00714180b3
c9d548c91f net: remove CService::ToStringPort() (Vasil Dimov)
fd4f0f41e9 gui: simplify OptionsDialog::updateDefaultProxyNets() (Vasil Dimov)
96c791dd20 net: remove CService::ToString() use ToStringAddrPort() instead (Vasil Dimov)
944a9de08a net: remove CNetAddr::ToString() and use ToStringAddr() instead (Vasil Dimov)
043b9de59a scripted-diff: rename ToStringIP[Port]() to ToStringAddr[Port]() (Vasil Dimov)
Pull request description:
Before this PR we had the somewhat confusing combination of methods:
`CNetAddr::ToStringIP()`
`CNetAddr::ToString()` (duplicate of the above)
`CService::ToStringIPPort()`
`CService::ToString()` (duplicate of the above, overrides a non-virtual method from `CNetAddr`)
`CService::ToStringPort()`
Avoid [overriding non-virtual methods](https://github.com/bitcoin/bitcoin/pull/25349/#issuecomment-1185226396).
"IP" stands for "Internet Protocol" and while sometimes "IP addresses" are called just "IPs", it is incorrect to call Tor or I2P addresses "IPs". Thus use "Addr" instead of "IP".
Change the above to:
`CNetAddr::ToStringAddr()`
`CService::ToStringAddrPort()`
The changes touch a lot of files, but are mostly mechanical.
ACKs for top commit:
sipa:
utACK c9d548c91f
achow101:
ACK c9d548c91f
jonatack:
re-ACK c9d548c91f only change since my previous reviews is rebase, but as a sanity check rebased to current master and at each commit quickly re-reviewed and re-verified clean build and green unit tests
LarryRuane:
ACK c9d548c91f
Tree-SHA512: 633fb044bdecf9f551b5e3314c385bf10e2b78e8027dc51ec324b66b018da35e5b01f3fbe6295bbc455ea1bcd1a3629de1918d28de510693afaf6a52693f2157
that was resolved in PR27036 "test: Remove last uses of snprintf and simplify"
and while here, fix up 2 words in docs to make the spelling linter green again.
691eaf8873 Pass MSG_MORE flag when sending non-final network messages (Matt Whitlock)
Pull request description:
**N.B.:** This is my second attempt at introducing this optimization. #12519 (2018) was closed in deference to switching to doing gathering socket writes using `sendmsg(2)`, which I agree would have superior performance due to fewer syscalls, but that work was apparently abandoned in late 2018. Ever since, Bitcoin Core has continued writing tons of runt packets to the wire. Can we proceed with my halfway solution for now?
----
Since Nagle's algorithm is disabled, each and every call to `send(2)` can potentially generate a separate TCP segment on the wire. This is especially inefficient when sending the tiny header preceding each message payload.
Linux implements a `MSG_MORE` flag that tells the kernel not to push the passed data immediately to the connected peer but rather to collect it in the socket's internal transmit buffer where it can be combined with data from successive calls to `send(2)`. Where available, specify this flag when calling `send(2)` in `CConnman::SocketSendData(CNode &)` if the data buffer being sent is not the last one in `node.vSendMsg`.
ACKs for top commit:
sipa:
ACK 691eaf8873
vasild:
ACK 691eaf8873
Tree-SHA512: 9a7f46bc12edbf78d488f05d1c46760110a24c95af74b627d2604fcd198fa3f511c5956bac36d0034e88c632d432f7d394147e667a11b027af0a30f70a546d70
dfc01ccd73 net: simplify the call to vProcessMsg.splice() (Vasil Dimov)
Pull request description:
At the time when
```cpp
pnode->vProcessMsg.splice(pnode->vProcessMsg.end(), pnode->vRecvMsg, pnode->vRecvMsg.begin(), it);
```
is called, `it` is certainly `pnode->vRecvMsg.end()` which makes the call equivalent to:
```cpp
pnode->vProcessMsg.splice(pnode->vProcessMsg.end(), pnode->vRecvMsg, pnode->vRecvMsg.begin(), pnode->vRecvMsg.end());
```
which is equivalent to:
```cpp
pnode->vProcessMsg.splice(pnode->vProcessMsg.end(), pnode->vRecvMsg);
```
Thus, use the latter. Further, maybe irrelevant, but the latter has constant complexity while the original code is `O(length of vRecvMsg)`.
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Tree-SHA512: 9f4eb61d1caf4af9a61ba2f54b915fcfe406db62c58ab1ec42f736505b6792e9379a83d0458d6cc04f289edcec070b7c962f94a920ab51701c3cab103152866f
At the time when
```cpp
pnode->vProcessMsg.splice(pnode->vProcessMsg.end(), pnode->vRecvMsg, pnode->vRecvMsg.begin(), it);
```
is called, `it` is certainly `pnode->vRecvMsg.end()` which makes the
call equivalent to:
```cpp
pnode->vProcessMsg.splice(pnode->vProcessMsg.end(), pnode->vRecvMsg, pnode->vRecvMsg.begin(), pnode->vRecvMsg.end());
```
which is equivalent to:
```cpp
pnode->vProcessMsg.splice(pnode->vProcessMsg.end(), pnode->vRecvMsg);
```
Thus, use the latter. Further, maybe irrelevant, but the latter has
constant complexity while the original code is `O(length of vRecvMsg)`.
The functionality of the old size() is covered by the new Size()
when no arguments are specified, so this does not change behavior.
Co-authored-by: Martin Zumsande <mzumsande@gmail.com>
Previously, we'd only load fixed seeds if we'd not
know any addresses at all. This change makes it possible
to change -onlynet abruptly, e.g. from -onlynet=onion to
-onlynet=i2p and still find peers.
