When using remote includes with certain setups, one could get weird

rehash errors such as error: set::geoip-classic::ipv6-database:
cannot open file "/home/xxxx/unrealircd/data/https://www.unrealircd...
and possibly even a crash.
The initial boot of UnrealIRCd, however, was always fine, this only
happened when rehashing.
It also seemed to occur more with ftp:// includes or at least with
multiple parallel includes, that may or may not have different or
more latency. In any case it seemed to affect some remote includes
setups semi-consistently, and others not at all.

The root cause was a complex code path causing a read-after-free.
We now use a simplified code path which can no longer cause this.
The only downside is that rehashing may be delayed up to an extra
250ms (quarter of a second), but that should hardly be noticeable,
if at all.

Issue reported by Bun-Bun.

include/h.h

@@ -518,6 +518,7 @@ extern int  channel_canjoin(Client *client, const char *name);
 extern char *collapse(char *pattern);
 extern void dcc_sync(Client *client);
 extern void request_rehash(Client *client);
+extern int rehash_internal(Client *client);
 extern void s_die();
 extern int match_simple(const char *mask, const char *name);
 extern int match_esc(const char *mask, const char *name);

src/conf.c

@@ -10638,13 +10638,6 @@ void resource_download_complete(const char *url, const char *file, const char *e
 				safe_strdup(wce->ce->value, rs->file); // now information of url is lost, hm!!
 		}
 	}
-
-	/* If rehashing, check if we are done.
-	 * If booting (not rehashing), this is done from the
-	 * startup loop where it also checks is_config_read_finished().
-	 */
-	if (loop.rehashing && is_config_read_finished())
-		rehash_internal(loop.rehash_save_client);
 }
 
 /** Request to REHASH the configuration file.

src/ircd.c

@@ -914,6 +914,9 @@ void SocketLoop(void *dummy)
 			reinit_tls();
 			doreloadcert = 0;
 		}
+		/* If rehashing, check if we are done. */
+		if (loop.rehashing && is_config_read_finished())
+			rehash_internal(loop.rehash_save_client);
 	}
 }