/* * 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 #include #include #include #include #include #include #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); } // 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(data_); for (; NLMSG_OK(hdr, static_cast(bytes_read)); hdr = NLMSG_NEXT(hdr, bytes_read)) { if (hdr->nlmsg_type == NLMSG_DONE) return true; if (hdr->nlmsg_type == NLMSG_ERROR) return false; callback(context, hdr); } } // We only get here if recv fails before we see a NLMSG_DONE. return false; }