Move DNS TTL manipulation code to src/core/or

This removes a dependency from the client code on feature/relay.

src/feature/client/addressmap.c

@@ -23,7 +23,6 @@
 #include "app/config/config.h"
 #include "core/or/connection_edge.h"
 #include "feature/control/control_events.h"
-#include "feature/relay/dns.h"
 #include "feature/nodelist/nodelist.h"
 #include "feature/nodelist/routerset.h"
 

src/feature/relay/dns.c

@@ -268,22 +268,6 @@ has_dns_init_failed(void)
   return nameserver_config_failed;
 }
 
-/** Helper: Given a TTL from a DNS response, determine what TTL to give the
- * OP that asked us to resolve it, and how long to cache that record
- * ourselves. */
-uint32_t
-clip_dns_ttl(uint32_t ttl)
-{
-  /* This logic is a defense against "DefectTor" DNS-based traffic
-   * confirmation attacks, as in https://nymity.ch/tor-dns/tor-dns.pdf .
-   * We only give two values: a "low" value and a "high" value.
-   */
-  if (ttl < MIN_DNS_TTL)
-    return MIN_DNS_TTL;
-  else
-    return MAX_DNS_TTL;
-}
-
 /** Helper: free storage held by an entry in the DNS cache. */
 static void
 free_cached_resolve_(cached_resolve_t *r)

src/feature/relay/dns.h

@@ -12,22 +12,9 @@
 #ifndef TOR_DNS_H
 #define TOR_DNS_H
 
-/** Lowest value for DNS ttl that a server will give. */
-#define MIN_DNS_TTL (5*60)
-/** Highest value for DNS ttl that a server will give. */
-#define MAX_DNS_TTL (60*60)
-
-/** How long do we keep DNS cache entries before purging them (regardless of
- * their TTL)? */
-#define MAX_DNS_ENTRY_AGE (3*60*60)
-/** How long do we cache/tell clients to cache DNS records when no TTL is
- * known? */
-#define DEFAULT_DNS_TTL (30*60)
-
 int dns_init(void);
 int has_dns_init_failed(void);
 void dns_free_all(void);
-uint32_t clip_dns_ttl(uint32_t ttl);
 int dns_reset(void);
 void connection_dns_remove(edge_connection_t *conn);
 void assert_connection_edge_not_dns_pending(edge_connection_t *conn);
@@ -74,4 +61,3 @@ launch_resolve,(cached_resolve_t *resolve));
 #endif /* defined(DNS_PRIVATE) */
 
 #endif /* !defined(TOR_DNS_H) */
-