player: Drop long-disabled code to resolve IP addresses

Disabled since commit 32fac04 (v4.2.13) because it could at the time
use more stack space than we provided.  Additional issues: code still
uses obsolete gethostbyaddr() rather than getnameinfo(), and we
provide only 512 bytes for host names instead of the customary
NI_MAXHOST (1025) bytes.

All three issues would be easy enough to fix.  What's not so easy is
to avoid blocking on the synchronous DNS lookup.  Without that,
connecting repeatedly from a range of addresses with slow reverse
lookup could conceivably be employed as a denial of service attack.

We've been living without reverse lookup for close to ten years.  Bury
the corpse, and move on.

Bonus: sizeof(struct natstr) is cut in half.

Signed-off-by: Markus Armbruster <armbru@pond.sub.org>

include/misc.h

@@ -29,7 +29,7 @@
  *
  *  Known contributors to this file:
  *     Doug Hay, 1998
- *     Markus Armbruster, 2004-2013
+ *     Markus Armbruster, 2004-2014
  */
 
 #ifndef MISC_H
@@ -51,15 +51,6 @@
 #define ATTRIBUTE(attrs)
 #endif
 
-/*
- * This uses a lot of thread stack with some versions of GNU libc,
- * which can lead to nasty heap smashes (observed with 2.2.93).
- * Disabled for now, until we readjust thread stack sizes.
- */
-#if 0
-#define RESOLVE_IPADDRESS	/* resolve ip addresses into hostnames */
-#endif
-
 #ifndef bit
 #define bit(x)		(1<<(x))
 #endif

include/nat.h

@@ -31,7 +31,7 @@
  *     Ken Stevens, 1995
  *     Steve McClure, 1998-2000
  *     Ron Koenderink, 2005-2008
- *     Markus Armbruster, 2005-2013
+ *     Markus Armbruster, 2005-2014
  */
 
 #ifndef NAT_H
@@ -95,7 +95,6 @@ struct natstr {
     char nat_cnam[20];		/* country name */
     char nat_pnam[20];		/* representative */
     char nat_hostaddr[46];	/* host addr of last user */
-    char nat_hostname[512];	/* hostname of last user, may be empty */
     char nat_userid[32];	/* userid of last user, may be empty */
     coord nat_xcap, nat_ycap;	/* cap location in abs coords */
     coord nat_xorg, nat_yorg;	/* origin location in abs coords */

include/player.h

@@ -59,7 +59,6 @@ struct player {
     struct emp_qelem queue;
     empth_t *proc;
     char hostaddr[46];
-    char hostname[512];		/* may be empty */
     char client[128];		/* may be empty */
     char userid[32];		/* may be empty */
     int authenticated;

src/lib/player/accept.c

@@ -28,7 +28,7 @@
  *
  *  Known contributors to this file:
  *     Dave Pare, 1994
- *     Markus Armbruster, 2005-2013
+ *     Markus Armbruster, 2005-2014
  */
 
 #include <config.h>
@@ -174,9 +174,6 @@ player_accept(void *unused)
     int ns;
     int set = 1;
     char buf[128];
-#ifdef RESOLVE_IPADDRESS
-    struct hostent *hostp;
-#endif
 
     /* auto sockaddr_storage would be simpler, but less portable */
     sap = malloc(player_addrlen);
@@ -212,11 +209,6 @@ player_accept(void *unused)
 	    continue;
 	}
 	logerror("Connect from %s", np->hostaddr);
-#ifdef RESOLVE_IPADDRESS
-	hostp = gethostbyaddr(inaddr, player_addrlen, sap->sa_family);
-	if (NULL != hostp)
-	    strcpy(np->hostname, hostp->h_name);
-#endif /* RESOLVE_IPADDRESS */
 	sprintf(buf, "Conn%d", conn_cnt++);
 	empth_create(player_login, 1024 * 1024, 0, buf, np);
     }

src/lib/player/player.c

@@ -80,11 +80,9 @@ player_main(struct player *p)
 	   natp->nat_last_login <= natp->nat_last_logout
 	   ? ctime(&natp->nat_last_logout) : "?");
 	pr("                  by: %s@%s\n",
-	   natp->nat_userid,
+	   natp->nat_userid, natp->nat_hostaddr);
-	   *natp->nat_hostname ? natp->nat_hostname : natp->nat_hostaddr);
     }
     strcpy(natp->nat_userid, player->userid);
-    strcpy(natp->nat_hostname, player->hostname);
     strcpy(natp->nat_hostaddr, player->hostaddr);
     natp->nat_last_login = player->curup;
     putnat(natp);
@@ -289,6 +287,5 @@ quit(void)
 char *
 praddr(struct player *p)
 {
-    return prbuf("%s@%s", p->userid,
+    return prbuf("%s@%s", p->userid, p->hostaddr);
-		 *p->hostname ? p->hostname : p->hostaddr);
 }