/*
Copyright (c) 2011, The WebRTC project authors. 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.

  * Neither the name of Google nor the names of its contributors may
    be used to endorse or promote products derived from this software
    without specific prior written permission.

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
HOLDER 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.
*/

#if defined(ANDROID)
#include "ifaddrs-android.h"
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/utsname.h>
#include <sys/ioctl.h>
#include <netinet/in.h>
#include <net/if.h>
#include <unistd.h>
#include <errno.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>

struct netlinkrequest {
  struct nlmsghdr header;
  struct ifaddrmsg msg;
};

static const int kMaxReadSize = 4096;

static int set_ifname(struct ifaddrs* ifaddr, int interface) {
  char buf[IFNAMSIZ] = {0};
  char* name = if_indextoname(interface, buf);
  if (name == NULL) {
    return -1;
  }
  ifaddr->ifa_name = malloc(strlen(name) + 1);
  strncpy(ifaddr->ifa_name, name, strlen(name) + 1);
  return 0;
}

static int set_flags(struct ifaddrs* ifaddr) {
  int fd = socket(AF_INET, SOCK_DGRAM, 0);
  if (fd == -1) {
    return -1;
  }
  struct ifreq ifr;
  memset(&ifr, 0, sizeof(ifr));
  strncpy(ifr.ifr_name, ifaddr->ifa_name, IFNAMSIZ - 1);
  int rc = ioctl(fd, SIOCGIFFLAGS, &ifr);
  close(fd);
  if (rc == -1) {
    return -1;
  }
  ifaddr->ifa_flags = ifr.ifr_flags;
  return 0;
}

static int set_addresses(struct ifaddrs* ifaddr, struct ifaddrmsg* msg, void* data,
                  size_t len) {
  if (msg->ifa_family == AF_INET) {
    struct sockaddr_in* sa = malloc(sizeof(struct sockaddr_in));
    memset(sa, 0, sizeof(struct sockaddr_in));
    sa->sin_family = AF_INET;
    memcpy(&sa->sin_addr, data, len);
    ifaddr->ifa_addr = (struct sockaddr*)sa;
  } else if (msg->ifa_family == AF_INET6) {
    struct sockaddr_in6* sa = malloc(sizeof(struct sockaddr_in6));
    memset(sa, 0, sizeof(struct sockaddr_in6));
    sa->sin6_family = AF_INET6;
    sa->sin6_scope_id = msg->ifa_index;
    memcpy(&sa->sin6_addr, data, len);
    ifaddr->ifa_addr = (struct sockaddr*)sa;
  } else {
    return -1;
  }
  return 0;
}

static int make_prefixes(struct ifaddrs* ifaddr, int family, int prefixlen) {
  char* prefix = NULL;
  if (family == AF_INET) {
    struct sockaddr_in* mask = malloc(sizeof(struct sockaddr_in));
    memset(mask, 0, sizeof(struct sockaddr_in));
    mask->sin_family = AF_INET;
    memset(&mask->sin_addr, 0, sizeof(struct in_addr));
    ifaddr->ifa_netmask = (struct sockaddr*)mask;
    if (prefixlen > 32) {
      prefixlen = 32;
    }
    prefix = (char*)&mask->sin_addr;
  } else if (family == AF_INET6) {
    struct sockaddr_in6* mask = malloc(sizeof(struct sockaddr_in6));
    memset(mask, 0, sizeof(struct sockaddr_in6));
    mask->sin6_family = AF_INET6;
    memset(&mask->sin6_addr, 0, sizeof(struct in6_addr));
    ifaddr->ifa_netmask = (struct sockaddr*)mask;
    if (prefixlen > 128) {
      prefixlen = 128;
    }
    prefix = (char*)&mask->sin6_addr;
  } else {
    return -1;
  }
  for (int i = 0; i < (prefixlen / 8); i++) {
    *prefix++ = 0xFF;
  }
  char remainder = 0xff;
  remainder <<= (8 - prefixlen % 8);
  *prefix = remainder;
  return 0;
}

static int populate_ifaddrs(struct ifaddrs* ifaddr, struct ifaddrmsg* msg, void* bytes,
                     size_t len) {
  if (set_ifname(ifaddr, msg->ifa_index) != 0) {
    return -1;
  }
  if (set_flags(ifaddr) != 0) {
    return -1;
  }
  if (set_addresses(ifaddr, msg, bytes, len) != 0) {
    return -1;
  }
  if (make_prefixes(ifaddr, msg->ifa_family, msg->ifa_prefixlen) != 0) {
    return -1;
  }
  return 0;
}

int android_getifaddrs(struct ifaddrs** result) {
  int fd = socket(PF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
  if (fd < 0) {
    return -1;
  }

  struct netlinkrequest ifaddr_request;
  memset(&ifaddr_request, 0, sizeof(ifaddr_request));
  ifaddr_request.header.nlmsg_flags = NLM_F_ROOT | NLM_F_REQUEST;
  ifaddr_request.header.nlmsg_type = RTM_GETADDR;
  ifaddr_request.header.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifaddrmsg));

  ssize_t count = send(fd, &ifaddr_request, ifaddr_request.header.nlmsg_len, 0);
  if ((size_t)count != ifaddr_request.header.nlmsg_len) {
    close(fd);
    return -1;
  }
  struct ifaddrs* start = NULL;
  struct ifaddrs* current = NULL;
  char buf[kMaxReadSize];
  ssize_t amount_read = recv(fd, &buf, kMaxReadSize, 0);
  while (amount_read > 0) {
    struct nlmsghdr* header = (struct nlmsghdr*)&buf[0];
    size_t header_size = (size_t)amount_read;
    for ( ; NLMSG_OK(header, header_size);
          header = NLMSG_NEXT(header, header_size)) {
      switch (header->nlmsg_type) {
        case NLMSG_DONE:
          /* Success. Return. */
          *result = start;
          close(fd);
          return 0;
        case NLMSG_ERROR:
          close(fd);
          android_freeifaddrs(start);
          return -1;
        case RTM_NEWADDR: {
          struct ifaddrmsg* address_msg =
              (struct ifaddrmsg*)NLMSG_DATA(header);
          struct rtattr* rta = IFA_RTA(address_msg);
          ssize_t payload_len = IFA_PAYLOAD(header);
          while (RTA_OK(rta, payload_len)) {
            if (rta->rta_type == IFA_ADDRESS) {
              int family = address_msg->ifa_family;
              if (family == AF_INET || family == AF_INET6) {
                struct ifaddrs* newest = malloc(sizeof(struct ifaddrs));
                memset(newest, 0, sizeof(struct ifaddrs));
                if (current) {
                  current->ifa_next = newest;
                } else {
                  start = newest;
                }
                if (populate_ifaddrs(newest, address_msg, RTA_DATA(rta),
                                     RTA_PAYLOAD(rta)) != 0) {
                  android_freeifaddrs(start);
                  *result = NULL;
                  return -1;
                }
                current = newest;
              }
            }
            rta = RTA_NEXT(rta, payload_len);
          }
          break;
        }
      }
    }
    amount_read = recv(fd, &buf, kMaxReadSize, 0);
  }
  close(fd);
  android_freeifaddrs(start);
  return -1;
}

void android_freeifaddrs(struct ifaddrs* addrs) {
  struct ifaddrs* last = NULL;
  struct ifaddrs* cursor = addrs;
  while (cursor) {
    free(cursor->ifa_name);
    free(cursor->ifa_addr);
    free(cursor->ifa_netmask);
    last = cursor;
    cursor = cursor->ifa_next;
    free(last);
  }
}

#endif  /* defined(ANDROID) */
