1 /* 2 * Copyright (C) 2015 The Android Open Source Project 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * * Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * * Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in 12 * the documentation and/or other materials provided with the 13 * distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS 22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 #include "bionic_netlink.h" 30 31 #include <errno.h> 32 #include <linux/netlink.h> 33 #include <linux/rtnetlink.h> 34 #include <string.h> 35 #include <stdlib.h> 36 #include <sys/socket.h> 37 #include <unistd.h> 38 39 #include "private/ErrnoRestorer.h" 40 41 NetlinkConnection::NetlinkConnection() { 42 fd_ = -1; 43 44 // The kernel keeps packets under 8KiB (NLMSG_GOODSIZE), 45 // but that's a bit too large to go on the stack. 46 size_ = 8192; 47 data_ = new char[size_]; 48 } 49 50 NetlinkConnection::~NetlinkConnection() { 51 ErrnoRestorer errno_restorer; 52 if (fd_ != -1) close(fd_); 53 delete[] data_; 54 } 55 56 bool NetlinkConnection::SendRequest(int type) { 57 // Rather than force all callers to check for the unlikely event of being 58 // unable to allocate 8KiB, check here. 59 if (data_ == nullptr) return false; 60 61 // Did we open a netlink socket yet? 62 if (fd_ == -1) { 63 fd_ = socket(PF_NETLINK, SOCK_RAW | SOCK_CLOEXEC, NETLINK_ROUTE); 64 } 65 66 // Construct and send the message. 67 struct NetlinkMessage { 68 nlmsghdr hdr; 69 rtgenmsg msg; 70 } request; 71 memset(&request, 0, sizeof(request)); 72 request.hdr.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST; 73 request.hdr.nlmsg_type = type; 74 request.hdr.nlmsg_len = sizeof(request); 75 request.msg.rtgen_family = AF_UNSPEC; // All families. 76 return (TEMP_FAILURE_RETRY(send(fd_, &request, sizeof(request), 0)) == sizeof(request)); 77 } 78 79 bool NetlinkConnection::ReadResponses(void callback(void*, nlmsghdr*), void* context) { 80 // Read through all the responses, handing interesting ones to the callback. 81 ssize_t bytes_read; 82 while ((bytes_read = TEMP_FAILURE_RETRY(recv(fd_, data_, size_, 0))) > 0) { 83 nlmsghdr* hdr = reinterpret_cast<nlmsghdr*>(data_); 84 for (; NLMSG_OK(hdr, static_cast<size_t>(bytes_read)); hdr = NLMSG_NEXT(hdr, bytes_read)) { 85 if (hdr->nlmsg_type == NLMSG_DONE) return true; 86 if (hdr->nlmsg_type == NLMSG_ERROR) return false; 87 callback(context, hdr); 88 } 89 } 90 91 // We only get here if recv fails before we see a NLMSG_DONE. 92 return false; 93 } 94