Waybar/src/modules/network.cpp

#include "modules/network.hpp"

waybar::modules::Network::Network(Json::Value config)
  : ALabel(std::move(config)), family_(AF_INET),
    signal_strength_dbm_(0), signal_strength_(0)
{
  sock_fd_ = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
  if (sock_fd_ < 0) {
    throw std::runtime_error("Can't open network socket");
  }
  nladdr_.nl_family = AF_NETLINK;
  nladdr_.nl_groups = RTMGRP_LINK | RTMGRP_IPV4_IFADDR;
  if (bind(sock_fd_, reinterpret_cast<struct sockaddr *>(&nladdr_),
    sizeof(nladdr_)) != 0) {
    throw std::runtime_error("Can't bind network socket");
  }
  if (config_["interface"]) {
    ifid_ = if_nametoindex(config_["interface"].asCString());
    ifname_ = config_["interface"].asString();
    if (ifid_ <= 0) {
      throw std::runtime_error("Can't found network interface");
    }
  } else {
    ifid_ = getExternalInterface();
    if (ifid_ > 0) {
      char ifname[IF_NAMESIZE];
      if_indextoname(ifid_, ifname);
      ifname_ = ifname;
    }
  }
  label_.set_name("network");
  // Trigger first values
  getInfo();
  update();
  thread_.sig_update.connect(sigc::mem_fun(*this, &Network::update));
  thread_ = [this] {
    char buf[4096];
    uint64_t len = netlinkResponse(sock_fd_, buf, sizeof(buf),
      RTMGRP_LINK | RTMGRP_IPV4_IFADDR);
    bool need_update = false;
    for (auto nh = reinterpret_cast<struct nlmsghdr *>(buf); NLMSG_OK(nh, len);
      nh = NLMSG_NEXT(nh, len)) {
      if (nh->nlmsg_type == NLMSG_DONE) {
        break;
      }
      if (nh->nlmsg_type == NLMSG_ERROR) {
        continue;
      }
      if (nh->nlmsg_type < RTM_NEWADDR) {
        auto rtif = static_cast<struct ifinfomsg *>(NLMSG_DATA(nh));
        if (rtif->ifi_index == static_cast<int>(ifid_)) {
          need_update = true;
          if (!(rtif->ifi_flags & IFF_RUNNING)) {
            disconnected();
          }
        }
      }
    }
    if (ifid_ <= 0 && !config_["interface"]) {
      // Need to wait before get external interface
      thread_.sleep_for(std::chrono::seconds(1));
      ifid_ = getExternalInterface();
      if (ifid_ > 0) {
        char ifname[IF_NAMESIZE];
        if_indextoname(ifid_, ifname);
        ifname_ = ifname;
        need_update = true;
      }
    }
    if (need_update) {
      getInfo();
      thread_.sig_update.emit();
    }
  };
}

waybar::modules::Network::~Network()
{
  close(sock_fd_);
}

auto waybar::modules::Network::update() -> void
{
  auto format = config_["format"] ? config_["format"].asString() : "{ifname}";
  if (ifid_ <= 0) {
    format = config_["format-disconnected"]
      ? config_["format-disconnected"].asString() : format;
    label_.get_style_context()->add_class("disconnected");
  } else {
    if (essid_.empty()) {
      format = config_["format-ethernet"]
        ? config_["format-ethernet"].asString() : format;
    } else {
      format = config_["format-wifi"]
        ? config_["format-wifi"].asString() : format;
    }
    label_.get_style_context()->remove_class("disconnected");
  }
  label_.set_text(fmt::format(format,
    fmt::arg("essid", essid_),
    fmt::arg("signaldBm", signal_strength_dbm_),
    fmt::arg("signalStrength", signal_strength_),
    fmt::arg("ifname", ifname_)
  ));
}

void waybar::modules::Network::disconnected()
{
  essid_.clear();
  signal_strength_dbm_ = 0;
  signal_strength_ = 0;
  ifname_.clear();
  ifid_ = -1;
}

// Based on https://gist.github.com/Yawning/c70d804d4b8ae78cc698
int waybar::modules::Network::getExternalInterface()
{
  struct nlmsghdr *hdr = nullptr;
  struct rtmsg *rt = nullptr;
  void *resp = nullptr;
  int ifidx = -1;

  /* Allocate space for the request. */
  uint32_t reqlen = NLMSG_SPACE(sizeof(*rt));
  void *req = nullptr;
  if ((req = calloc(1, reqlen)) == nullptr) {
    goto out; /* ENOBUFS */
  }

  /* Build the RTM_GETROUTE request. */
  hdr = static_cast<struct nlmsghdr *>(req);
  hdr->nlmsg_len = NLMSG_LENGTH(sizeof(*rt));
  hdr->nlmsg_flags = NLM_F_REQUEST | NLM_F_DUMP;
  hdr->nlmsg_type = RTM_GETROUTE;
  rt = static_cast<struct rtmsg *>(NLMSG_DATA(hdr));
  rt->rtm_family = family_;
  rt->rtm_table = RT_TABLE_MAIN;

  /* Issue the query. */
  if (netlinkRequest(sock_fd_, req, reqlen) < 0) {
    goto out;
  }

  /* Allocate space for the response. */
  static const uint32_t route_buffer_size = 8192;
  if ((resp = calloc(1, route_buffer_size)) == nullptr) {
    goto out; /* ENOBUFS */
  }

  /* Read the response(s).
   *
   * WARNING: All the packets generated by the request must be consumed (as in,
   * consume responses till NLMSG_DONE/NLMSG_ERROR is encountered).
   */
  do {
    uint64_t len = netlinkResponse(sock_fd_, resp, route_buffer_size);
    if (len < 0) {
      goto out;
    }

    /* Parse the response payload into netlink messages. */
    for (hdr = static_cast<struct nlmsghdr *>(resp); NLMSG_OK(hdr, len);
      hdr = NLMSG_NEXT(hdr, len)) {
      if (hdr->nlmsg_type == NLMSG_DONE) {
        goto out;
      }
      if (hdr->nlmsg_type == NLMSG_ERROR) {
        /* Even if we found the interface index, something is broken with the
         * netlink socket, so return an error.
         */
        ifidx = -1;
        goto out;
      }

      /* If we found the correct answer, skip parsing the attributes. */
      if (ifidx != -1) {
        continue;
      }

      /* Find the message(s) concerting the main routing table, each message
       * corresponds to a single routing table entry.
       */
      rt = static_cast<struct rtmsg *>(NLMSG_DATA(hdr));
      if (rt->rtm_table != RT_TABLE_MAIN) {
        continue;
      }

      /* Parse all the attributes for a single routing table entry. */
      struct rtattr *attr = RTM_RTA(rt);
      uint64_t attrlen = RTM_PAYLOAD(hdr);
      bool has_gateway = false;
      bool has_destination = false;
      int temp_idx = -1;
      for (; RTA_OK(attr, attrlen); attr = RTA_NEXT(attr, attrlen)) {
        /* Determine if this routing table entry corresponds to the default
         * route by seeing if it has a gateway, and if a destination addr is
         * set, that it is all 0s.
         */
        switch (attr->rta_type) {
          case RTA_GATEWAY:
            /* The gateway of the route.
             *
             * If someone every needs to figure out the gateway address as well,
             * it's here as the attribute payload.
             */
            has_gateway = true;
            break;
          case RTA_DST: {
            /* The destination address.
             * Should be either missing, or maybe all 0s.  Accept both.
             */
            const uint32_t nr_zeroes = (family_ == AF_INET) ? 4 : 16;
            unsigned char c = 0;
            size_t dstlen = RTA_PAYLOAD(attr);
            if (dstlen != nr_zeroes) {
              break;
            }
            for (uint32_t i = 0; i < dstlen; i += 1) {
              c |= *(unsigned char *)(RTA_DATA(attr) + i);
            }
            has_destination = (c == 0);
            break;
          }
          case RTA_OIF:
            /* The output interface index. */
            temp_idx = *static_cast<int*>(RTA_DATA(attr));
            break;
          default:
            break;
        }
      }
      /* If this is the default route, and we know the interface index,
       * we can stop parsing this message.
       */
      if (has_gateway && !has_destination && temp_idx != -1) {
        ifidx = temp_idx;
        break;
      }
    }
  } while (true);

out:
  if (req != nullptr)
    free(req);
  if (resp != nullptr)
    free(resp);
  return ifidx;
}

uint64_t waybar::modules::Network::netlinkRequest(int fd, void *req,
  uint32_t reqlen, uint32_t groups)
{
  struct sockaddr_nl sa = {0};
  sa.nl_family = AF_NETLINK;
  sa.nl_groups = groups;
  struct iovec iov = { req, reqlen };
  struct msghdr msg = { &sa, sizeof(sa), &iov, 1, nullptr, 0, 0 };
  return sendmsg(fd, &msg, 0);
}

uint64_t waybar::modules::Network::netlinkResponse(int fd, void *resp,
  uint32_t resplen, uint32_t groups)
{
  uint64_t ret;
  struct sockaddr_nl sa = {0};
  sa.nl_family = AF_NETLINK;
  sa.nl_groups = groups;
  struct iovec iov = { resp, resplen };
  struct msghdr msg = { &sa, sizeof(sa), &iov, 1, nullptr, 0, 0 };
  ret = recvmsg(fd, &msg, 0);
  if (msg.msg_flags & MSG_TRUNC)
    return -1;
  return ret;
}

int waybar::modules::Network::scanCb(struct nl_msg *msg, void *data) {
    auto net = static_cast<waybar::modules::Network *>(data);
    auto gnlh = static_cast<genlmsghdr *>(nlmsg_data(nlmsg_hdr(msg)));
    struct nlattr* tb[NL80211_ATTR_MAX + 1];
    struct nlattr* bss[NL80211_BSS_MAX + 1];
    struct nla_policy bss_policy[NL80211_BSS_MAX + 1]{};
    bss_policy[NL80211_BSS_TSF].type = NLA_U64;
    bss_policy[NL80211_BSS_FREQUENCY].type = NLA_U32;
    bss_policy[NL80211_BSS_BSSID].type = NLA_UNSPEC;
    bss_policy[NL80211_BSS_BEACON_INTERVAL].type = NLA_U16;
    bss_policy[NL80211_BSS_CAPABILITY].type = NLA_U16;
    bss_policy[NL80211_BSS_INFORMATION_ELEMENTS].type = NLA_UNSPEC;
    bss_policy[NL80211_BSS_SIGNAL_MBM].type = NLA_U32;
    bss_policy[NL80211_BSS_SIGNAL_UNSPEC].type = NLA_U8;
    bss_policy[NL80211_BSS_STATUS].type = NLA_U32;

    if (nla_parse(tb, NL80211_ATTR_MAX, genlmsg_attrdata(gnlh, 0), genlmsg_attrlen(gnlh, 0), nullptr) < 0) {
      return NL_SKIP;
    }
    if (tb[NL80211_ATTR_BSS] == nullptr) {
      return NL_SKIP;
    }
    if (nla_parse_nested(bss, NL80211_BSS_MAX, tb[NL80211_ATTR_BSS], bss_policy) != 0) {
      return NL_SKIP;
    }
    if (!net->associatedOrJoined(bss)) {
      return NL_SKIP;
    }
    net->parseEssid(bss);
    net->parseSignal(bss);
    // TODO(someone): parse quality
    return NL_SKIP;
}

void waybar::modules::Network::parseEssid(struct nlattr **bss)
{
  essid_.clear();
  if (bss[NL80211_BSS_INFORMATION_ELEMENTS] != nullptr) {
    auto ies =
      static_cast<char*>(nla_data(bss[NL80211_BSS_INFORMATION_ELEMENTS]));
    auto ies_len = nla_len(bss[NL80211_BSS_INFORMATION_ELEMENTS]);
    const auto hdr_len = 2;
    while (ies_len > hdr_len && ies[0] != 0) {
      ies_len -= ies[1] + hdr_len;
      ies += ies[1] + hdr_len;
    }
    if (ies_len > hdr_len && ies_len > ies[1] + hdr_len) {
      auto essid_begin = ies + hdr_len;
      auto essid_end = essid_begin + ies[1];
      std::copy(essid_begin, essid_end, std::back_inserter(essid_));
    }
  }
}

void waybar::modules::Network::parseSignal(struct nlattr **bss) {
    if (bss[NL80211_BSS_SIGNAL_MBM] != nullptr) {
      // signalstrength in dBm
      signal_strength_dbm_ =
        static_cast<int>(nla_get_u32(bss[NL80211_BSS_SIGNAL_MBM])) / 100;

      // WiFi-hardware usually operates in the range -90 to -20dBm.
      const int hardwareMax = -20;
      const int hardwareMin = -90;
      signal_strength_ = ((signal_strength_dbm_ - hardwareMin)
        / double{hardwareMax - hardwareMin}) * 100;
    }
  }

bool waybar::modules::Network::associatedOrJoined(struct nlattr** bss)
{
    if (bss[NL80211_BSS_STATUS] == nullptr) {
      return false;
    }
    auto status = nla_get_u32(bss[NL80211_BSS_STATUS]);
    switch (status) {
      case NL80211_BSS_STATUS_ASSOCIATED:
      case NL80211_BSS_STATUS_IBSS_JOINED:
      case NL80211_BSS_STATUS_AUTHENTICATED:
        return true;
      default:
        return false;
    }
  }

auto waybar::modules::Network::getInfo() -> void
{
	struct nl_sock *sk = nl_socket_alloc();
	if (genl_connect(sk) != 0) {
    nl_socket_free(sk);
    return;
  }
  if (nl_socket_modify_cb(sk, NL_CB_VALID, NL_CB_CUSTOM, scanCb, this) < 0) {
    nl_socket_free(sk);
    return;
  }
  const int nl80211_id = genl_ctrl_resolve(sk, "nl80211");
  if (nl80211_id < 0) {
    nl_socket_free(sk);
    return;
  }
  struct nl_msg *msg = nlmsg_alloc();
  if (msg == nullptr) {
    nl_socket_free(sk);
    return;
  }
  if (genlmsg_put(msg, NL_AUTO_PORT, NL_AUTO_SEQ, nl80211_id, 0, NLM_F_DUMP,
    NL80211_CMD_GET_SCAN, 0) == nullptr
    || nla_put_u32(msg, NL80211_ATTR_IFINDEX, ifid_) < 0) {
    nlmsg_free(msg);
    return;
  }
  nl_send_sync(sk, msg);
  nl_socket_free(sk);
}