text: /*
   * 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.
   */
  
  #ifndef IFADDRS_ANDROID_H_included
  #define IFADDRS_ANDROID_H_included
  
  #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 "LocalArray.h"
  #include "ScopedFd.h"
  
  // Android (bionic) doesn't have getifaddrs(3)/freeifaddrs(3).
  // We fake it here, so java_net_NetworkInterface.cpp can use that API
  // with all the non-portable code being in this file.
  
  // Source-compatible subset of the BSD struct.
  struct ifaddrs {
      // Pointer to next struct in list, or NULL at end.
      ifaddrs* ifa_next;
  
      // Interface name.
      char* ifa_name;
  
      // Interface flags.
      unsigned int ifa_flags;
  
      // Interface network address.
      sockaddr* ifa_addr;
  
      // Interface netmask.
      sockaddr* ifa_netmask;
  
      ifaddrs(ifaddrs* next)
      : ifa_next(next), ifa_name(NULL), ifa_flags(0), ifa_addr(NULL), ifa_netmask(NULL)
      {
      }
  
      ~ifaddrs() {
          delete ifa_next;
          delete[] ifa_name;
          delete ifa_addr;
          delete ifa_netmask;
      }
  
      // 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.
      bool setNameAndFlagsByIndex(int interfaceIndex) {
          // Get the name.
          char buf[IFNAMSIZ];
          char* name = if_indextoname(interfaceIndex, buf);
          if (name == NULL) {
              return false;
          }
          ifa_name = new char[strlen(name) + 1];
          strcpy(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_flags = ifr.ifr_flags;
          return true;
      }
  
      // 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.
      void setAddress(int family, void* data, size_t byteCount) {
          // Set the address proper...
          sockaddr_storage* ss = new sockaddr_storage;
          memset(ss, 0, sizeof(*ss));
          ifa_addr = reinterpret_cast<sockaddr*>(ss);
          ss->ss_family = family;
          uint8_t* dst = sockaddrBytes(family, ss);
          memcpy(dst, data, byteCount);
      }
  
      // Netlink gives us the prefix length as a bit count. We need to turn
      // that into a BSD-compatible netmask represented by a sockaddr*.
      void setNetmask(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));
          ifa_netmask = reinterpret_cast<sockaddr*>(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)));
          }
      }
  
      // Returns a pointer to the first byte in the address data (which is
      // stored in network byte order).
      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;
      }
  
  private:
      // Disallow copy and assignment.
      ifaddrs(const ifaddrs&);
      void operator=(const ifaddrs&);
  };
  
  // FIXME: use iovec instead.
  struct addrReq_struct {
      nlmsghdr netlinkHeader;
      ifaddrmsg msg;
  };
  
  inline 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));
  }
  
  inline ssize_t recvNetlinkMessage(int fd, char* buf, size_t byteCount) {
      return TEMP_FAILURE_RETRY(recv(fd, buf, byteCount, 0));
  }
  
  // Source-compatible with the BSD function.
  inline 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.
      addrReq_struct addrRequest;
      memset(&addrRequest, 0, sizeof(addrRequest));
      addrRequest.netlinkHeader.nlmsg_flags = NLM_F_REQUEST | NLM_F_MATCH;
      addrRequest.netlinkHeader.nlmsg_type = RTM_GETADDR;
      addrRequest.netlinkHeader.nlmsg_len = NLMSG_ALIGN(NLMSG_LENGTH(sizeof(addrRequest)));
      addrRequest.msg.ifa_family = AF_UNSPEC; // All families.
      addrRequest.msg.ifa_index = 0; // All interfaces.
      if (!sendNetlinkMessage(fd.get(), &addrRequest, addrRequest.netlinkHeader.nlmsg_len)) {
          return -1;
      }
  
      // Read the responses.
      LocalArray<0> buf(65536); // We don't necessarily have std::vector.
      ssize_t bytesRead;
      while ((bytesRead  = recvNetlinkMessage(fd.get(), &buf[0], buf.size())) > 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:
                  {
                      ifaddrmsg* address = reinterpret_cast<ifaddrmsg*>(NLMSG_DATA(hdr));
                      rtattr* rta = IFA_RTA(address);
                      size_t ifaPayloadLength = IFA_PAYLOAD(hdr);
                      while (RTA_OK(rta, ifaPayloadLength)) {
                          if (rta->rta_type == IFA_LOCAL) {
                              int family = address->ifa_family;
                              if (family == AF_INET || family == AF_INET6) {
                                  *result = new ifaddrs(*result);
                                  if (!(*result)->setNameAndFlagsByIndex(address->ifa_index)) {
                                      return -1;
                                  }
                                  (*result)->setAddress(family, RTA_DATA(rta), RTA_PAYLOAD(rta));
                                  (*result)->setNetmask(family, address->ifa_prefixlen);
                              }
                          }
                          rta = RTA_NEXT(rta, ifaPayloadLength);
                      }
                  }
                  break;
              }
          }
      }
      // We only get here if recv fails before we see a NLMSG_DONE.
      return -1;
  }
  
  // Source-compatible with the BSD function.
  inline void freeifaddrs(ifaddrs* addresses) {
      delete addresses;
  }
  
  #endif  // IFADDRS_ANDROID_H_included
  