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/*
* Copyright (C) 2015 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include "bionic_netlink.h"
#include <errno.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#include <string.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <unistd.h>
#include "private/ErrnoRestorer.h"
NetlinkConnection::NetlinkConnection() {
fd_ = -1;
// The kernel keeps packets under 8KiB (NLMSG_GOODSIZE),
// but that's a bit too large to go on the stack.
size_ = 8192;
data_ = new char[size_];
}
NetlinkConnection::~NetlinkConnection() {
ErrnoRestorer errno_restorer;
if (fd_ != -1) close(fd_);
delete[] data_;
}
bool NetlinkConnection::SendRequest(int type) {
// Rather than force all callers to check for the unlikely event of being
// unable to allocate 8KiB, check here.
if (data_ == nullptr) return false;
// Did we open a netlink socket yet?
if (fd_ == -1) {
fd_ = socket(PF_NETLINK, SOCK_RAW | SOCK_CLOEXEC, NETLINK_ROUTE);
if (fd_ == -1) return false;
}
// Construct and send the message.
struct NetlinkMessage {
nlmsghdr hdr;
rtgenmsg msg;
} request;
memset(&request, 0, sizeof(request));
request.hdr.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST;
request.hdr.nlmsg_type = type;
request.hdr.nlmsg_len = sizeof(request);
request.msg.rtgen_family = AF_UNSPEC; // All families.
return (TEMP_FAILURE_RETRY(send(fd_, &request, sizeof(request), 0)) == sizeof(request));
}
bool NetlinkConnection::ReadResponses(void callback(void*, nlmsghdr*), void* context) {
// Read through all the responses, handing interesting ones to the callback.
ssize_t bytes_read;
while ((bytes_read = TEMP_FAILURE_RETRY(recv(fd_, data_, size_, 0))) > 0) {
nlmsghdr* hdr = reinterpret_cast<nlmsghdr*>(data_);
for (; NLMSG_OK(hdr, static_cast<size_t>(bytes_read)); hdr = NLMSG_NEXT(hdr, bytes_read)) {
if (hdr->nlmsg_type == NLMSG_DONE) return true;
if (hdr->nlmsg_type == NLMSG_ERROR) {
nlmsgerr* err = reinterpret_cast<nlmsgerr*>(NLMSG_DATA(hdr));
errno = (hdr->nlmsg_len >= NLMSG_LENGTH(sizeof(nlmsgerr))) ? -err->error : EIO;
return false;
}
callback(context, hdr);
}
}
// We only get here if recv fails before we see a NLMSG_DONE.
return false;
}
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