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/*
* Copyright (C) 2009 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.
*/
#ifdef HAVE_ANDROID_OS
#include "ifaddrs-android.h"
#include <arpa/inet.h>
#include <cstring>
#include <errno.h>
#include <net/if.h>
#include <netinet/in.h>
#include <new>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#include "ScopedFd.h"
#include "UniquePtr.h"
ifaddrs::ifaddrs(ifaddrs* next, sockaddr* ifa_addr, sockaddr* ifa_netmask)
: ifa_next(next), ifa_name(NULL), ifa_flags(0), ifa_addr(ifa_addr), ifa_netmask(ifa_netmask)
{
}
ifaddrs::~ifaddrs() {
delete ifa_next;
delete[] ifa_name;
delete ifa_addr;
delete ifa_netmask;
}
static bool sendNetlinkMessage(int fd, const void* data, size_t byteCount) {
ssize_t sentByteCount = TEMP_FAILURE_RETRY(send(fd, data, byteCount, 0));
return (sentByteCount == static_cast<ssize_t>(byteCount));
}
static ssize_t recvNetlinkMessage(int fd, char* buf, size_t byteCount) {
return TEMP_FAILURE_RETRY(recv(fd, buf, byteCount, 0));
}
// Returns a pointer to the first byte in the address data (which is
// stored in network byte order).
static uint8_t* sockaddrBytes(int family, sockaddr_storage* ss) {
if (family == AF_INET) {
sockaddr_in* ss4 = reinterpret_cast<sockaddr_in*>(ss);
return reinterpret_cast<uint8_t*>(&ss4->sin_addr);
} else if (family == AF_INET6) {
sockaddr_in6* ss6 = reinterpret_cast<sockaddr_in6*>(ss);
return reinterpret_cast<uint8_t*>(&ss6->sin6_addr);
}
return NULL;
}
// Netlink gives us the address family in the header, and the
// sockaddr_in or sockaddr_in6 bytes as the payload. We need to
// stitch the two bits together into the sockaddr that's part of
// our portable interface.
static sockaddr* toSocketAddress(int family, void* data, size_t byteCount) {
// Set the address proper...
sockaddr_storage* ss = new sockaddr_storage;
memset(ss, 0, sizeof(*ss));
ss->ss_family = family;
uint8_t* dst = sockaddrBytes(family, ss);
memcpy(dst, data, byteCount);
return reinterpret_cast<sockaddr*>(ss);
}
// Netlink gives us the prefix length as a bit count. We need to turn
// that into a BSD-compatible netmask represented by a sockaddr*.
static sockaddr* toNetmask(int family, size_t prefixLength) {
// ...and work out the netmask from the prefix length.
sockaddr_storage* ss = new sockaddr_storage;
memset(ss, 0, sizeof(*ss));
ss->ss_family = family;
uint8_t* dst = sockaddrBytes(family, ss);
memset(dst, 0xff, prefixLength / 8);
if ((prefixLength % 8) != 0) {
dst[prefixLength/8] = (0xff << (8 - (prefixLength % 8)));
}
return reinterpret_cast<sockaddr*>(ss);
}
// Sadly, we can't keep the interface index for portability with BSD.
// We'll have to keep the name instead, and re-query the index when
// we need it later.
static bool setNameAndFlagsByIndex(ifaddrs* ifa, int interfaceIndex) {
// Get the name.
char buf[IFNAMSIZ];
char* name = if_indextoname(interfaceIndex, buf);
if (name == NULL) {
return false;
}
ifa->ifa_name = new char[strlen(name) + 1];
strcpy(ifa->ifa_name, name);
// Get the flags.
ScopedFd fd(socket(AF_INET, SOCK_DGRAM, 0));
if (fd.get() == -1) {
return false;
}
ifreq ifr;
memset(&ifr, 0, sizeof(ifr));
strcpy(ifr.ifr_name, name);
int rc = ioctl(fd.get(), SIOCGIFFLAGS, &ifr);
if (rc == -1) {
return false;
}
ifa->ifa_flags = ifr.ifr_flags;
return true;
}
// Source-compatible with the BSD function.
int getifaddrs(ifaddrs** result) {
// Simplify cleanup for callers.
*result = NULL;
// Create a netlink socket.
ScopedFd fd(socket(AF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE));
if (fd.get() < 0) {
return -1;
}
// Ask for the address information.
struct {
nlmsghdr netlinkHeader;
ifaddrmsg msg;
} request;
memset(&request, 0, sizeof(request));
request.netlinkHeader.nlmsg_flags = NLM_F_ROOT | NLM_F_REQUEST | NLM_F_MATCH;
request.netlinkHeader.nlmsg_type = RTM_GETADDR;
request.netlinkHeader.nlmsg_len = NLMSG_ALIGN(NLMSG_LENGTH(sizeof(request)));
request.msg.ifa_family = AF_UNSPEC; // All families.
request.msg.ifa_index = 0; // All interfaces.
if (!sendNetlinkMessage(fd.get(), &request, request.netlinkHeader.nlmsg_len)) {
return -1;
}
// Read the responses.
const size_t bufferSize = 65536;
UniquePtr<char[]> buf(new char[bufferSize]);
ssize_t bytesRead;
while ((bytesRead = recvNetlinkMessage(fd.get(), &buf[0], bufferSize)) > 0) {
nlmsghdr* hdr = reinterpret_cast<nlmsghdr*>(&buf[0]);
for (; NLMSG_OK(hdr, (size_t)bytesRead); hdr = NLMSG_NEXT(hdr, bytesRead)) {
switch (hdr->nlmsg_type) {
case NLMSG_DONE:
return 0;
case NLMSG_ERROR:
return -1;
case RTM_NEWADDR:
{
// A given RTM_NEWADDR payload may contain multiple addresses. The while loop
// below iterates through them. These locals contain the best address we've
// seen so far.
int ifa_index = -1;
UniquePtr<sockaddr> ifa_addr;
UniquePtr<sockaddr> ifa_netmask;
ifaddrmsg* address = reinterpret_cast<ifaddrmsg*>(NLMSG_DATA(hdr));
rtattr* rta = IFA_RTA(address);
size_t ifaPayloadLength = IFA_PAYLOAD(hdr);
while (RTA_OK(rta, ifaPayloadLength)) {
// We can't just use IFA_ADDRESS because it's the destination address for
// a point-to-point interface; we can't just use IFA_LOCAL because we don't
// always have it. That is: we want IFA_LOCAL if we get it, but IFA_ADDRESS
// otherwise. We take advantage of the fact that the kernel returns
// IFA_LOCAL (if available) second.
if (rta->rta_type == IFA_LOCAL || rta->rta_type == IFA_ADDRESS) {
int family = address->ifa_family;
if (family == AF_INET || family == AF_INET6) {
ifa_index = address->ifa_index;
ifa_addr.reset(toSocketAddress(family, RTA_DATA(rta), RTA_PAYLOAD(rta)));
ifa_netmask.reset(toNetmask(family, address->ifa_prefixlen));
}
}
rta = RTA_NEXT(rta, ifaPayloadLength);
}
// Did we get a usable address? If so, thread it on our list.
if (ifa_index != -1) {
*result = new ifaddrs(*result, ifa_addr.release(), ifa_netmask.release());
if (!setNameAndFlagsByIndex(*result, ifa_index)) {
return -1;
}
}
}
break;
}
}
}
// We only get here if recv fails before we see a NLMSG_DONE.
return -1;
}
// Source-compatible with the BSD function.
void freeifaddrs(ifaddrs* addresses) {
delete addresses;
}
#endif
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