ident.c: add support for IPv6

Add IPv6 support by implementing name resolution with the
protocol agnostic getaddrinfo(3) API. The old gethostbyname(3)
code is still available when git is compiled with NO_IPV6.

Signed-off-by: Elia Pinto <gitter.spiros@gmail.com>
Helped-by: Jeff King <peff@peff.net>
Helped-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Jeff King <peff@peff.net>

diff --git a/ident.c b/ident.c
index 5ff1aadaaaa999df3bfecb07f84f259469b3a54d..4e7f99d5dd79745e53c55e8ae39ab12dc39789df 100644 (file)
--- a/ident.c
+++ b/ident.c
@@ -70,10 +70,35 @@ static int add_mailname_host(struct strbuf *buf)
        return 0;
 }
 
+static int canonical_name(const char *host, struct strbuf *out)
+{
+       int status = -1;
+
+#ifndef NO_IPV6
+       struct addrinfo hints, *ai;
+       memset (&hints, '\0', sizeof (hints));
+       hints.ai_flags = AI_CANONNAME;
+       if (!getaddrinfo(host, NULL, &hints, &ai)) {
+               if (ai && strchr(ai->ai_canonname, '.')) {
+                       strbuf_addstr(out, ai->ai_canonname);
+                       status = 0;
+               }
+               freeaddrinfo(ai);
+       }
+#else
+       struct hostent *he = gethostbyname(buf);
+       if (he && strchr(he->h_name, '.')) {
+               strbuf_addstr(out, he->h_name);
+               status = 0;
+       }
+#endif /* NO_IPV6 */
+
+       return status;
+}
+
 static void add_domainname(struct strbuf *out)
 {
        char buf[1024];
-       struct hostent *he;
 
        if (gethostname(buf, sizeof(buf))) {
                warning("cannot get host name: %s", strerror(errno));
@@ -82,9 +107,7 @@ static void add_domainname(struct strbuf *out)
        }
        if (strchr(buf, '.'))
                strbuf_addstr(out, buf);
-       else if ((he = gethostbyname(buf)) && strchr(he->h_name, '.'))
-               strbuf_addstr(out, he->h_name);
-       else
+       else if (canonical_name(buf, out) < 0)
                strbuf_addf(out, "%s.(none)", buf);
 }