const std::string sockaddrToInterfaceName()

in gloo/transport/tcp/device.cc [177:213]

• 33 lines of code
• 9 McCabe index (conditional complexity)

const std::string sockaddrToInterfaceName(const struct attr& attr) {
  struct ifaddrs* ifap;
  std::string iface;
  auto rv = getifaddrs(&ifap);
  GLOO_ENFORCE_NE(rv, -1, strerror(errno));
  auto addrIsLocalhost = isLocalhostAddr((struct sockaddr*)&attr.ai_addr);
  struct ifaddrs *ifa;
  for (ifa = ifap; ifa != nullptr; ifa = ifa->ifa_next) {
    // Skip entry if ifa_addr is NULL (see getifaddrs(3))
    if (ifa->ifa_addr == nullptr) {
      continue;
    }
    if (ifa->ifa_addr->sa_family == AF_INET) {
      auto sz = sizeof(struct sockaddr_in);
      // Check if this interface address matches the provided address, or if
      // this is the localhost interface and the provided address is in the
      // localhost subnet.
      if ((memcmp(&attr.ai_addr, ifa->ifa_addr, sz) == 0) ||
          (addrIsLocalhost && isLocalhostAddr(ifa->ifa_addr))) {
        iface = ifa->ifa_name;
        break;
      }
    } else if (ifa->ifa_addr->sa_family == AF_INET6) {
      auto sz = sizeof(struct sockaddr_in6);
      if (memcmp(&attr.ai_addr, ifa->ifa_addr, sz) == 0) {
        iface = ifa->ifa_name;
        break;
      }
    }
  }
  GLOO_ENFORCE(
    ifa != nullptr,
    "Unable to find interface for: ",
    Address(attr.ai_addr).str());
  freeifaddrs(ifap);
  return iface;
}