Add IPv6 support to getifaddrs() on Windows

We now ask both IPv4 and IPv6 addresses to GetAdaptersAddresses

Ipv6 address flags fill up is left as a todo because
I'm not sure how to get the same information as of Linux

I've tested on a x86_64 Windows machine and I get the same
informations as of ipconfig.exe

libc/calls/ioctl.c

@@ -43,6 +43,7 @@
 #include "libc/runtime/runtime.h"
 #include "libc/runtime/stack.h"
 #include "libc/serialize.h"
+#include "libc/sock/in.h"
 #include "libc/sock/internal.h"
 #include "libc/sock/struct/ifconf.h"
 #include "libc/sock/struct/ifreq.h"
@@ -68,6 +69,11 @@ static struct HostAdapterInfoNode {
   struct sockaddr unicast;
   struct sockaddr netmask;
   struct sockaddr broadcast;
+  uint16_t ifindex6;  /* Interface index */
+  uint16_t flags6;    /* Flags */
+  uint8_t scope6;     /* Addr scope */
+  uint8_t prefixlen6; /* Prefix length */
+  struct in6_addr addr6;
   short flags;
 } *__hostInfo;
 
@@ -153,7 +159,8 @@ static textwindows struct HostAdapterInfoNode *findAdapterByName(
     const char *name) {
   struct HostAdapterInfoNode *node = __hostInfo;
   while (node) {
-    if (!strncmp(name, node->name, IFNAMSIZ)) {
+    if (!strncmp(name, node->name, IFNAMSIZ) &&
+        node->unicast.sa_family == AF_INET) {
       return node;
     }
     node = node->next;
@@ -178,7 +185,7 @@ static textwindows struct HostAdapterInfoNode *appendHostInfo(
         *ptrUA, /* Ptr to ptr to unicast address list node */
     struct NtIpAdapterPrefix *
         *ptrAP,    /* Ptr to ptr to Adapter prefix list node */
-    int count) { /* count is used to create a unique name in case of alias */
+    int *ip4cnt) { /* count is used to create a unique name in case of alias */
 
   struct HostAdapterInfoNode *temp;
   struct HostAdapterInfoNode *node;
@@ -193,18 +200,17 @@ static textwindows struct HostAdapterInfoNode *appendHostInfo(
 
   memcpy(node->name, baseName, IFNAMSIZ);
 
-  /* Are there more than a single unicast address ? */
+  /* Are there more than a single IPv4 unicast address ? */
-  if (count > 0 || ((*ptrUA)->Next != NULL)) {
+  if (*ip4cnt > 0) {
-    /* Yes, compose it using <baseName>:<count> */
+    /* Yes, compose it using <baseName>:<ip4cnt> */
     size_t nameLen = strlen(node->name);
     if (nameLen + 2 > IFNAMSIZ - 2) {
       /* Appending the ":x" will exceed the size, need to chop the end */
       nameLen -= 2;
     }
     node->name[nameLen - 2] = ':';
-    node->name[nameLen - 1] = '0' + count;
+    node->name[nameLen - 1] = '0' + *ip4cnt;
     node->name[nameLen] = '\0';
-  }
 
     /* Is there a name clash with other interfaces? */
     for (attemptNum = 0; attemptNum < MAX_NAME_CLASH; ++attemptNum) {
@@ -232,6 +238,7 @@ static textwindows struct HostAdapterInfoNode *appendHostInfo(
       errno = EEXIST;
       return NULL;
     }
+  }
 
   /* Finally we got a unique short and friendly name */
   node->unicast = *((*ptrUA)->Address.lpSockaddr);
@@ -267,6 +274,9 @@ static textwindows struct HostAdapterInfoNode *appendHostInfo(
       node->flags = 0;
   }
 
+  int family = ((struct sockaddr_in *)(*ptrUA)->Address.lpSockaddr)->sin_family;
+  if (family == AF_INET) {
+    *ip4cnt += 1;
     ip = ntohl(
         ((struct sockaddr_in *)(*ptrUA)->Address.lpSockaddr)->sin_addr.s_addr);
     netmask = (uint32_t)-1 << (32 - (*ptrUA)->OnLinkPrefixLength);
@@ -320,6 +330,30 @@ static textwindows struct HostAdapterInfoNode *appendHostInfo(
         }
       }
     }
+  } else if (family == AF_INET6) {
+    node->addr6 =
+        ((struct sockaddr_in6 *)(*ptrUA)->Address.lpSockaddr)->sin6_addr;
+    node->ifindex6 =
+        ((struct sockaddr_in6 *)(*ptrUA)->Address.lpSockaddr)->sin6_scope_id;
+    node->prefixlen6 = (*ptrUA)->OnLinkPrefixLength;
+    node->scope6 = 0;
+    if (IN6_IS_ADDR_LINKLOCAL(&node->addr6)) {
+      node->scope6 = 0x20;  // link
+    } else if (IN6_IS_ADDR_SITELOCAL(&node->addr6)) {
+      node->scope6 = 0x40;  // site
+    } else if (IN6_IS_ADDR_LOOPBACK(&node->addr6)) {
+      node->scope6 = 0x10;  // host
+    }
+    node->flags6 = 0;  // TODO ipv6 addr flags
+
+    // Move Prefix ptr
+    if (ptrAP && *ptrAP) {
+      *ptrAP = (*ptrAP)->Next; /* skip net ip */
+      if (*ptrAP) {
+        *ptrAP = (*ptrAP)->Next; /* skip host ip */
+      }
+    }
+  }
 
   *ptrUA = (*ptrUA)->Next;
 
@@ -341,14 +375,13 @@ static textwindows int createHostInfo(
   struct NtIpAdapterPrefix *ap;
   struct HostAdapterInfoNode *node = NULL;
   char baseName[IFNAMSIZ];
-  int count, i;
+  int ip4cnt, i;
   /* __hostInfo must be empty */
   unassert(__hostInfo == NULL);
   for (aa = firstAdapter; aa; aa = aa->Next) {
-    /* Skip all the interfaces with no address and the ones that are not AF_INET
+    /* Skip all the interfaces with no address
      */
-    if (!aa->FirstUnicastAddress ||
+    if (!aa->FirstUnicastAddress) {
-        aa->FirstUnicastAddress->Address.lpSockaddr->sa_family != AF_INET) {
       continue;
     }
     /* Use max IFNAMSIZ-1 chars, leave the last char for eventual conflicts */
@@ -361,9 +394,11 @@ static textwindows int createHostInfo(
       if (!baseName[i])
         break;
     }
-    for (count = 0, ua = aa->FirstUnicastAddress, ap = aa->FirstPrefix;
+    ua = aa->FirstUnicastAddress;
-         (ua != NULL) && (count < MAX_UNICAST_ADDR); ++count) {
+    ap = aa->FirstPrefix;
-      node = appendHostInfo(node, baseName, aa, &ua, &ap, count);
+    ip4cnt = 0;
+    while (ua != NULL) {
+      node = appendHostInfo(node, baseName, aa, &ua, &ap, &ip4cnt);
       if (!node)
         goto err;
       if (!__hostInfo) {
@@ -390,9 +425,9 @@ static textwindows int readAdapterAddresses(void) {
   struct NtIpAdapterAddresses *aa = NULL;
   /*
    * Calculate the required data size
-   * Note: alternatively you can use AF_UNSPEC to also return IPv6 interfaces
+   * Note: AF_UNSPEC return both IPv4 and IPv6 interfaces
    */
-  rc = GetAdaptersAddresses(AF_INET,
+  rc = GetAdaptersAddresses(AF_UNSPEC,
                             kNtGaaFlagSkipAnycast | kNtGaaFlagSkipMulticast |
                                 kNtGaaFlagSkipDnsServer |
                                 kNtGaaFlagIncludePrefix,
@@ -409,7 +444,7 @@ static textwindows int readAdapterAddresses(void) {
     goto err;
   }
   /* Re-run GetAdaptersAddresses this time with a valid buffer */
-  rc = GetAdaptersAddresses(AF_INET,
+  rc = GetAdaptersAddresses(AF_UNSPEC,
                             kNtGaaFlagSkipAnycast | kNtGaaFlagSkipMulticast |
                                 kNtGaaFlagSkipDnsServer |
                                 kNtGaaFlagIncludePrefix,
@@ -446,8 +481,19 @@ static textwindows int ioctl_siocgifconf_nt(int fd, struct ifconf *ifc) {
   for (ptr = ifc->ifc_req, node = __hostInfo;
        (((char *)(ptr + 1) - ifc->ifc_buf) < ifc->ifc_len) && node;
        ptr++, node = node->next) {
+    bzero(ptr, sizeof(struct ifreq));
     memcpy(ptr->ifr_name, node->name, IFNAMSIZ);
+    int family = node->unicast.sa_family;
+    if (family == AF_INET) {
       memcpy(&ptr->ifr_addr, &node->unicast, sizeof(struct sockaddr));
+    } else if (family == AF_INET6) {
+      ptr->ifr_ifru.in6.sa_family = AF_INET6;
+      ptr->ifr6_ifindex = node->ifindex6;
+      ptr->ifr6_flags = node->flags6;
+      ptr->ifr6_scope = node->scope6;
+      ptr->ifr6_prefixlen = node->prefixlen6;
+      memcpy(&ptr->ifr6_addr, &node->addr6, sizeof(struct in6_addr));
+    }
   }
   ifc->ifc_len = (char *)ptr - ifc->ifc_buf;
   return 0;