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/*
* Copyright (C) 2019 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <libnl++/Socket.h>
#include <libnl++/printer.h>
#include <android-base/logging.h>
namespace android::nl {
/**
* Print all outbound/inbound Netlink messages.
*/
static constexpr bool kSuperVerbose = false;
Socket::Socket(int protocol, unsigned pid, uint32_t groups) : mProtocol(protocol) {
mFd.reset(socket(AF_NETLINK, SOCK_RAW, protocol));
if (!mFd.ok()) {
PLOG(ERROR) << "Can't open Netlink socket";
mFailed = true;
return;
}
sockaddr_nl sa = {};
sa.nl_family = AF_NETLINK;
sa.nl_pid = pid;
sa.nl_groups = groups;
if (bind(mFd.get(), reinterpret_cast<sockaddr*>(&sa), sizeof(sa)) < 0) {
PLOG(ERROR) << "Can't bind Netlink socket";
mFd.reset();
mFailed = true;
}
}
bool Socket::send(const Buffer<nlmsghdr>& msg, const sockaddr_nl& sa) {
if constexpr (kSuperVerbose) {
LOG(VERBOSE) << (mFailed ? "(not) " : "") << "sending to " << sa.nl_pid << ": "
<< toString(msg, mProtocol);
}
if (mFailed) return false;
mSeq = msg->nlmsg_seq;
const auto rawMsg = msg.getRaw();
const auto bytesSent = sendto(mFd.get(), rawMsg.ptr(), rawMsg.len(), 0,
reinterpret_cast<const sockaddr*>(&sa), sizeof(sa));
if (bytesSent < 0) {
PLOG(ERROR) << "Can't send Netlink message";
return false;
} else if (size_t(bytesSent) != rawMsg.len()) {
LOG(ERROR) << "Can't send Netlink message: truncated message";
return false;
}
return true;
}
bool Socket::send(const Buffer<nlmsghdr>& msg, uint32_t destination) {
sockaddr_nl sa = {.nl_family = AF_NETLINK, .nl_pad = 0, .nl_pid = destination, .nl_groups = 0};
return send(msg, sa);
}
bool Socket::increaseReceiveBuffer(size_t maxSize) {
if (maxSize == 0) {
LOG(ERROR) << "Maximum receive size should not be zero";
return false;
}
if (mReceiveBuffer.size() < maxSize) mReceiveBuffer.resize(maxSize);
return true;
}
std::optional<Buffer<nlmsghdr>> Socket::receive(size_t maxSize) {
return receiveFrom(maxSize).first;
}
std::pair<std::optional<Buffer<nlmsghdr>>, sockaddr_nl> Socket::receiveFrom(size_t maxSize) {
if (mFailed) return {std::nullopt, {}};
if (!increaseReceiveBuffer(maxSize)) return {std::nullopt, {}};
sockaddr_nl sa = {};
socklen_t saLen = sizeof(sa);
const auto bytesReceived = recvfrom(mFd.get(), mReceiveBuffer.data(), maxSize, MSG_TRUNC,
reinterpret_cast<sockaddr*>(&sa), &saLen);
if (bytesReceived <= 0) {
PLOG(ERROR) << "Failed to receive Netlink message";
return {std::nullopt, {}};
} else if (size_t(bytesReceived) > maxSize) {
PLOG(ERROR) << "Received data larger than maximum receive size: " //
<< bytesReceived << " > " << maxSize;
return {std::nullopt, {}};
}
Buffer<nlmsghdr> msg(reinterpret_cast<nlmsghdr*>(mReceiveBuffer.data()), bytesReceived);
if constexpr (kSuperVerbose) {
LOG(VERBOSE) << "received from " << sa.nl_pid << ": " << toString(msg, mProtocol);
}
return {msg, sa};
}
bool Socket::receiveAck(uint32_t seq) {
const auto nlerr = receive<nlmsgerr>({NLMSG_ERROR});
if (!nlerr.has_value()) return false;
if (nlerr->data.msg.nlmsg_seq != seq) {
LOG(ERROR) << "Received ACK for a different message (" << nlerr->data.msg.nlmsg_seq
<< ", expected " << seq << "). Multi-message tracking is not implemented.";
return false;
}
if (nlerr->data.error == 0) return true;
LOG(WARNING) << "Received Netlink error message: " << strerror(-nlerr->data.error);
return false;
}
std::optional<Buffer<nlmsghdr>> Socket::receive(const std::set<nlmsgtype_t>& msgtypes,
size_t maxSize) {
if (mFailed || !increaseReceiveBuffer(maxSize)) return std::nullopt;
for (const auto rawMsg : *this) {
if (msgtypes.count(rawMsg->nlmsg_type) == 0) {
LOG(WARNING) << "Received (and ignored) unexpected Netlink message of type "
<< rawMsg->nlmsg_type;
continue;
}
return rawMsg;
}
return std::nullopt;
}
std::optional<unsigned> Socket::getPid() {
if (mFailed) return std::nullopt;
sockaddr_nl sa = {};
socklen_t sasize = sizeof(sa);
if (getsockname(mFd.get(), reinterpret_cast<sockaddr*>(&sa), &sasize) < 0) {
PLOG(ERROR) << "Failed to get PID of Netlink socket";
return std::nullopt;
}
return sa.nl_pid;
}
pollfd Socket::preparePoll(short events) {
return {mFd.get(), events, 0};
}
bool Socket::addMembership(unsigned group) {
const auto res =
setsockopt(mFd.get(), SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, &group, sizeof(group));
if (res < 0) {
PLOG(ERROR) << "Failed joining multicast group " << group;
return false;
}
return true;
}
bool Socket::dropMembership(unsigned group) {
const auto res =
setsockopt(mFd.get(), SOL_NETLINK, NETLINK_DROP_MEMBERSHIP, &group, sizeof(group));
if (res < 0) {
PLOG(ERROR) << "Failed leaving multicast group " << group;
return false;
}
return true;
}
Socket::receive_iterator::receive_iterator(Socket& socket, bool end)
: mSocket(socket), mIsEnd(end) {
if (!end) receive();
}
Socket::receive_iterator Socket::receive_iterator::operator++() {
CHECK(!mIsEnd) << "Trying to increment end iterator";
++mCurrent;
if (mCurrent.isEnd()) receive();
return *this;
}
bool Socket::receive_iterator::operator==(const receive_iterator& other) const {
if (mIsEnd != other.mIsEnd) return false;
if (mIsEnd && other.mIsEnd) return true;
return mCurrent == other.mCurrent;
}
const Buffer<nlmsghdr>& Socket::receive_iterator::operator*() const {
CHECK(!mIsEnd) << "Trying to dereference end iterator";
return *mCurrent;
}
void Socket::receive_iterator::receive() {
CHECK(!mIsEnd) << "Trying to receive on end iterator";
CHECK(mCurrent.isEnd()) << "Trying to receive without draining previous read";
const auto buf = mSocket.receive();
if (buf.has_value()) {
mCurrent = buf->begin();
} else {
mIsEnd = true;
}
}
Socket::receive_iterator Socket::begin() {
return {*this, false};
}
Socket::receive_iterator Socket::end() {
return {*this, true};
}
} // namespace android::nl
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