Add per-client rate-limiting. The default limit is 1000 queries in 60…

… seconds.

Signed-off-by: DL6ER <dl6er@dl6er.de>

src/config.c

@@ -461,6 +461,25 @@ void read_FTLconf(void)
  logg(" REFRESH_HOSTNAMES: Periodically refreshing IPv4 names");
  }
 
+ // RATE_LIMIT
+ // defaults to: 1000 queries / 60 seconds
+ config.rate_limit.count = 1000;
+ config.rate_limit.interval = 60;
+ buffer = parse_FTLconf(fp, "RATE_LIMIT");
+
+ unsigned int count = 0, interval = 0;
+ if(buffer != NULL && sscanf(buffer, "%u/%u", &count, &interval) == 2)
+ {
+ config.rate_limit.count = count;
+ config.rate_limit.interval = interval;
+ }
+
+ if(config.rate_limit.count > 0)
+ logg(" RATE_LIMIT: Rate-limiting client making more than %u queries in %u second%s",
+ config.rate_limit.count, config.rate_limit.interval, config.rate_limit.interval == 1 ? "" : "s");
+ else
+ logg(" RATE_LIMIT: Disabled");
+
  // Read DEBUG_... setting from pihole-FTL.conf
  read_debuging_settings(fp);
 
@@ -523,7 +542,7 @@ static char *parse_FTLconf(FILE *fp, const char * key)
 
  // Go to beginning of file
  fseek(fp, 0L, SEEK_SET);
- 
+
  if(config.debug & DEBUG_EXTRA)
  logg("initial: conflinebuffer = %p, keystr = %p, size = %zu", conflinebuffer, keystr, size);
 

src/config.h

@@ -53,10 +53,14 @@ typedef struct {
  int dns_port;
  unsigned int delay_startup;
  unsigned int network_expire;
+ struct {
+ unsigned int count;
+ unsigned int interval;
+ } rate_limit;
  enum debug_flags debug;
  time_t DBinterval;
 } ConfigStruct;
-ASSERT_SIZEOF(ConfigStruct, 56, 48, 48);
+ASSERT_SIZEOF(ConfigStruct, 64, 56, 56);
 
 typedef struct {
  const char* conf;

src/database/query-table.c

@@ -432,7 +432,7 @@ void DB_read_queries(void)
  query->type = TYPE_OTHER;
  query->qtype = type - 100;
  }
- 
+
  query->status = status;
  query->domainID = domainID;
  query->clientID = clientID;

src/datastructure.h

@@ -79,6 +79,7 @@ typedef struct {
  int blockedcount;
  int aliasclient_id;
  unsigned int id;
+ unsigned int rate_limit;
  unsigned int numQueriesARP;
  int overTime[OVERTIME_SLOTS];
  size_t groupspos;
@@ -88,7 +89,7 @@ typedef struct {
  time_t lastQuery;
  time_t firstSeen;
 } clientsData;
-ASSERT_SIZEOF(clientsData, 688, 664, 664);
+ASSERT_SIZEOF(clientsData, 696, 668, 668);
 
 typedef struct {
  unsigned char magic;

src/dnsmasq_interface.c

@@ -190,8 +190,8 @@ static bool _FTL_check_blocking(int queryID, int domainID, int clientID, const c
  // as something along the CNAME path hit the whitelist
  if(!query->flags.whitelisted)
  {
- query_blocked(query, domain, client, QUERY_BLACKLIST);
  force_next_DNS_reply = dns_cache->force_reply;
+ query_blocked(query, domain, client, QUERY_BLACKLIST);
  return true;
  }
  break;
@@ -210,8 +210,8 @@ static bool _FTL_check_blocking(int queryID, int domainID, int clientID, const c
  // as sometving along the CNAME path hit the whitelist
  if(!query->flags.whitelisted)
  {
- query_blocked(query, domain, client, QUERY_GRAVITY);
  force_next_DNS_reply = dns_cache->force_reply;
+ query_blocked(query, domain, client, QUERY_GRAVITY);
  return true;
  }
  break;
@@ -532,19 +532,9 @@ bool _FTL_new_query(const unsigned int flags, const char *name,
  return false;
  }
 
- // Lock shared memory
- lock_shm();
-
- // Ensure we have enough space in the queries struct
- memory_check(QUERIES);
- const int queryID = counters->queries;
-
  // If domain is "pi.hole" we skip this query
  if(strcasecmp(name, "pi.hole") == 0)
- {
- unlock_shm();
  return false;
- }
 
  // Convert domain to lower case
  char *domainString = strdup(name);
@@ -574,10 +564,50 @@ bool _FTL_new_query(const unsigned int flags, const char *name,
  (strcmp(clientIP, "127.0.0.1") == 0 || strcmp(clientIP, "::1") == 0))
  {
  free(domainString);
+ return false;
+ }
+
+ // Lock shared memory
+ lock_shm();
+
+ // Find client IP
+ const int clientID = findClientID(clientIP, true, false);
+
+ // Get client pointer
+ clientsData* client = getClient(clientID, true);
+ if(client == NULL)
+ {
+ // Encountered memory error, skip query
+ // Free allocated memory
+ free(domainString);
+ // Release thread lock
  unlock_shm();
  return false;
  }
 
+ // Check rate-limit for this client
+ if(config.rate_limit.count > 0 &&
+ ++client->rate_limit > config.rate_limit.count)
+ {
+ if(config.debug & DEBUG_QUERIES)
+ {
+ logg("Rate-limiting %s %s query \"%s\" from %s:%s",
+ proto == TCP ? "TCP" : "UDP",
+ types, domainString, next_iface, clientIP);
+ }
+
+ // Block this query
+ force_next_DNS_reply = REFUSED;
+
+ // Do not further process this query, Pi-hole has never seen it
+ unlock_shm();
+ return true;
+ }
+
+ // Ensure we have enough space in the queries struct
+ memory_check(QUERIES);
+ const int queryID = counters->queries;
+
  // Log new query if in debug mode
  if(config.debug & DEBUG_QUERIES)
  {
@@ -607,9 +637,6 @@ bool _FTL_new_query(const unsigned int flags, const char *name,
  // Go through already knows domains and see if it is one of them
  const int domainID = findDomainID(domainString, true);
 
- // Go through already knows clients and see if it is one of them
- const int clientID = findClientID(clientIP, true, false);
-
  // Save everything
  queriesData* query = getQuery(queryID, false);
  if(query == NULL)
@@ -662,19 +689,6 @@ bool _FTL_new_query(const unsigned int flags, const char *name,
  // Update overTime data
  overTime[timeidx].total++;
 
- // Get client pointer
- clientsData* client = getClient(clientID, true);
- if(client == NULL)
- {
- // Encountered memory error, skip query
- logg("WARN: No memory available, skipping query analysis");
- // Free allocated memory
- free(domainString);
- // Release thread lock
- unlock_shm();
- return false;
- }
-
  // Update overTime data structure with the new client
  change_clientcount(client, 0, 0, timeidx, 1);
 
@@ -761,15 +775,23 @@ bool _FTL_new_query(const unsigned int flags, const char *name,
 void _FTL_get_blocking_metadata(union all_addr **addrp, unsigned int *flags, const char* file, const int line)
 {
  // Check first if we need to force our reply to something different than the
- // default/configured blocking mode For instance, we need to force NXDOMAIN
- // for intercepted _esni.* queries
+ // default/configured blocking mode. For instance, we need to force NXDOMAIN
+ // for intercepted _esni.* queries.
  if(force_next_DNS_reply == NXDOMAIN)
  {
  *flags = F_NXDOMAIN;
  // Reset DNS reply forcing
  force_next_DNS_reply = 0u;
  return;
  }
+ else if(force_next_DNS_reply == REFUSED)
+ {
+ // Empty flags result in REFUSED
+ *flags = 0;
+ // Reset DNS reply forcing
+ force_next_DNS_reply = 0u;
+ return;
+ }
 
  // Add flags according to current blocking mode
  // We bit-add here as flags already contains either F_IPV4 or F_IPV6
@@ -1662,7 +1684,7 @@ static void save_reply_type(const unsigned int flags, const union all_addr *addr
  queriesData* query, const struct timeval response)
 {
  // Iterate through possible values
- if(flags & F_NEG)
+ if(flags & F_NEG || force_next_DNS_reply == NXDOMAIN)
  {
  if(flags & F_NXDOMAIN)
  {
@@ -1694,15 +1716,15 @@ static void save_reply_type(const unsigned int flags, const union all_addr *addr
  // TXT query
  query->reply = REPLY_RRNAME;
  }
- else if(flags & F_RCODE && addr != NULL)
+ else if((flags & F_RCODE && addr != NULL) || force_next_DNS_reply == REFUSED)
  {
- const unsigned int rcode = addr->log.rcode;
- if(rcode == REFUSED)
+ if((addr != NULL && addr->log.rcode == REFUSED)
+  || force_next_DNS_reply == REFUSED )
  {
  // REFUSED query
  query->reply = REPLY_REFUSED;
  }
- else if(rcode == SERVFAIL)
+ else if(addr != NULL && addr->log.rcode == SERVFAIL)
  {
  // SERVFAIL query
  query->reply = REPLY_SERVFAIL;

src/gc.c

@@ -23,29 +23,46 @@
 
 bool doGC = false;
 
-time_t lastGCrun = 0;
+static void reset_rate_limiting(void)
+{
+ for(int clientID = 0; clientID < counters->clients; clientID++)
+ {
+ clientsData *client = getClient(clientID, true);
+ if(client != NULL)
+ client->rate_limit = 0;
+ }
+}
+
 void *GC_thread(void *val)
 {
  // Set thread name
  prctl(PR_SET_NAME,"housekeeper",0,0,0);
 
- // Save timestamp as we do not want to store immediately
- // to the database
- lastGCrun = time(NULL) - time(NULL)%GCinterval;
+ // Remember when we last ran the actions
+ time_t lastGCrun = time(NULL) - time(NULL)%GCinterval;
+ time_t lastRateLimitCleaner = time(NULL);
  while(!killed)
  {
- if(time(NULL) - GCdelay - lastGCrun >= GCinterval || doGC)
+ const time_t now = time(NULL);
+ if((unsigned int)(now - lastRateLimitCleaner) >= config.rate_limit.interval)
+ {
+ lastRateLimitCleaner = now;
+ lock_shm();
+ reset_rate_limiting();
+ unlock_shm();
+ }
+ if(now - GCdelay - lastGCrun >= GCinterval || doGC)
  {
  doGC = false;
  // Update lastGCrun timer
- lastGCrun = time(NULL) - GCdelay - (time(NULL) - GCdelay)%GCinterval;
+ lastGCrun = now - GCdelay - (now - GCdelay)%GCinterval;
 
  // Lock FTL's data structure, since it is likely that it will be changed here
  // Requests should not be processed/answered when data is about to change
  lock_shm();
 
  // Get minimum time stamp to keep
- time_t mintime = (time(NULL) - GCdelay) - MAXLOGAGE*3600;
+ time_t mintime = (now - GCdelay) - MAXLOGAGE*3600;
 
  // Align to the start of the next hour. This will also align with
  // the oldest overTime interval after GC is done.