mail.local: support IPv6 for biff notification

[Todd C. Miller]

Simple conversion to getaddrinfo.  Noticed while debugging a comsat
issue.

 - todd

Index: libexec/mail.local/mail.local.c
===================================================================
RCS file: /cvs/src/libexec/mail.local/mail.local.c,v
retrieving revision 1.33
diff -u -p -u -r1.33 mail.local.c
--- libexec/mail.local/mail.local.c     16 Jan 2015 06:39:50 -0000      1.33
+++ libexec/mail.local/mail.local.c     6 Jul 2015 13:09:00 -0000
@@ -289,32 +289,43 @@ bad:
 void
 notifybiff(char *msg)
 {
-       static struct sockaddr_in addr;
+       static struct addrinfo *res0;
+       struct addrinfo hints, *res;
        static int f = -1;
-       struct hostent *hp;
-       struct servent *sp;
        size_t len;
+       int error;
 
-       if (!addr.sin_family) {
-               /* Be silent if biff service not available. */
-               if (!(sp = getservbyname("biff", "udp")))
-                       return;
-               if (!(hp = gethostbyname("localhost"))) {
-                       merr(NOTFATAL, "localhost: %s", strerror(errno));
+       if (res0 == NULL) {
+               memset(&hints, 0, sizeof(hints));
+               hints.ai_family = PF_UNSPEC;
+               hints.ai_socktype = SOCK_DGRAM;
+
+               error = getaddrinfo("localhost", "biff", &hints, &res0);
+               if (error) {
+                       /* Be silent if biff service not available. */
+                       if (error != EAI_SERVICE) {
+                               merr(NOTFATAL, "localhost: %s",
+                                   gai_strerror(error));
+                       }
                        return;
                }
-               addr.sin_len = sizeof(struct sockaddr_in);
-               addr.sin_family = hp->h_addrtype;
-               addr.sin_port = sp->s_port;
-               bcopy(hp->h_addr, &addr.sin_addr, (size_t)hp->h_length);
        }
-       if (f < 0 && (f = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {
+
+       if (f == -1) {
+               for (res = res0; res != NULL; res = res->ai_next) {
+                       f = socket(res->ai_family, res->ai_socktype,
+                           res->ai_protocol);
+                       if (f != -1)
+                               break;
+               }
+       }
+       if (f == -1) {
                merr(NOTFATAL, "socket: %s", strerror(errno));
                return;
        }
+
        len = strlen(msg) + 1;
-       if (sendto(f, msg, len, 0, (struct sockaddr *)&addr, sizeof(addr))
-           != len)
+       if (sendto(f, msg, len, 0, res->ai_addr, res->ai_addrlen) != len)
                merr(NOTFATAL, "sendto biff: %s", strerror(errno));
 }