libuv源码阅读(9)--interfaces

#include <stdio.h>
#include <uv.h>

int main() {
    char buf[512];
    uv_interface_address_t *info;
    int count, i;

    uv_interface_addresses(&info, &count);
    i = count;

    printf("Number of interfaces: %d\n", count);
    while (i--) {
        uv_interface_address_t interface = info[i];

        printf("Name: %s\n", interface.name);
        printf("Internal? %s\n", interface.is_internal ? "Yes" : "No");
        
        if (interface.address.address4.sin_family == AF_INET) {
            uv_ip4_name(&interface.address.address4, buf, sizeof(buf));
            printf("IPv4 address: %s\n", buf);
        }
        else if (interface.address.address4.sin_family == AF_INET6) {
            uv_ip6_name(&interface.address.address6, buf, sizeof(buf));
            printf("IPv6 address: %s\n", buf);
        }

        printf("\n");
    }

    uv_free_interface_addresses(info, count);
    return 0;
}

struct uv_interface_address_s {
  char* name;
  char phys_addr[6];
  int is_internal;
  union {
    struct sockaddr_in address4;
    struct sockaddr_in6 address6;
  } address;
  union {
    struct sockaddr_in netmask4;
    struct sockaddr_in6 netmask6;
  } netmask;
};

static int uv__ifaddr_exclude(struct ifaddrs *ent, int exclude_type) {
  if (!((ent->ifa_flags & IFF_UP) && (ent->ifa_flags & IFF_RUNNING)))
    return 1;
  if (ent->ifa_addr == NULL)
    return 1;
  /*
   * On Linux getifaddrs returns information related to the raw underlying
   * devices. We're not interested in this information yet.
   */
  if (ent->ifa_addr->sa_family == PF_PACKET)
    return exclude_type;
  return !exclude_type;
}

int uv_interface_addresses(uv_interface_address_t** addresses, int* count) {
#ifndef HAVE_IFADDRS_H
  *count = 0;
  *addresses = NULL;
  return UV_ENOSYS;
#else
  struct ifaddrs *addrs, *ent;
  uv_interface_address_t* address;
  int i;
  struct sockaddr_ll *sll;

  *count = 0;
  *addresses = NULL;

  if (getifaddrs(&addrs))
    return UV__ERR(errno);

  /* Count the number of interfaces */
  for (ent = addrs; ent != NULL; ent = ent->ifa_next) {
    if (uv__ifaddr_exclude(ent, UV__EXCLUDE_IFADDR))
      continue;

    (*count)++;
  }

  if (*count == 0) {
    freeifaddrs(addrs);
    return 0;
  }

  /* Make sure the memory is initiallized to zero using calloc() */
  *addresses = uv__calloc(*count, sizeof(**addresses));
  if (!(*addresses)) {
    freeifaddrs(addrs);
    return UV_ENOMEM;
  }

  address = *addresses;

  for (ent = addrs; ent != NULL; ent = ent->ifa_next) {
    if (uv__ifaddr_exclude(ent, UV__EXCLUDE_IFADDR))
      continue;

    address->name = uv__strdup(ent->ifa_name);

    if (ent->ifa_addr->sa_family == AF_INET6) {
      address->address.address6 = *((struct sockaddr_in6*) ent->ifa_addr);
    } else {
      address->address.address4 = *((struct sockaddr_in*) ent->ifa_addr);
    }

    if (ent->ifa_netmask->sa_family == AF_INET6) {
      address->netmask.netmask6 = *((struct sockaddr_in6*) ent->ifa_netmask);
    } else {
      address->netmask.netmask4 = *((struct sockaddr_in*) ent->ifa_netmask);
    }

    address->is_internal = !!(ent->ifa_flags & IFF_LOOPBACK);

    address++;
  }

  /* Fill in physical addresses for each interface */
  for (ent = addrs; ent != NULL; ent = ent->ifa_next) {
    if (uv__ifaddr_exclude(ent, UV__EXCLUDE_IFPHYS))
      continue;

    address = *addresses;

    for (i = 0; i < (*count); i++) {
      size_t namelen = strlen(ent->ifa_name);
      /* Alias interface share the same physical address */
      if (strncmp(address->name, ent->ifa_name, namelen) == 0 &&
          (address->name[namelen] == 0 || address->name[namelen] == ':')) {
        sll = (struct sockaddr_ll*)ent->ifa_addr;
        memcpy(address->phys_addr, sll->sll_addr, sizeof(address->phys_addr));
      }
      address++;
    }
  }

  freeifaddrs(addrs);

  return 0;
#endif
}