Merge pull request #253 from pi-hole/FTLDNS-resolve

Internal name resolving functionality

FTL.h

@@ -159,12 +159,16 @@ typedef struct {
 	int count;
 	int failed;
 	char *ip;
+	char *name;
+	bool new;
 } forwardedDataStruct;
 
 typedef struct {
 	unsigned char magic;
 	int count;
 	char *ip;
+	char *name;
+	bool new;
 } clientsDataStruct;
 
 typedef struct {

Makefile

@@ -14,7 +14,7 @@ DNSMASQOPTS = -DHAVE_DNSSEC -DHAVE_DNSSEC_STATIC -DNO_FORK
 # Flags for compiling with libidn2: -DHAVE_LIBIDN2 -DIDN2_VERSION_NUMBER=0x02000003
 
 FTLDEPS = FTL.h routines.h version.h api.h dnsmasq_interface.h
-FTLOBJ = main.o memory.o log.o daemon.o datastructure.o signals.o socket.o request.o grep.o setupVars.o args.o threads.o gc.o config.o database.o msgpack.o api.o dnsmasq_interface.o
+FTLOBJ = main.o memory.o log.o daemon.o datastructure.o signals.o socket.o request.o grep.o setupVars.o args.o threads.o gc.o config.o database.o msgpack.o api.o dnsmasq_interface.o resolve.o
 
 DNSMASQDEPS = config.h dhcp-protocol.h dns-protocol.h radv-protocol.h dhcp6-protocol.h dnsmasq.h ip6addr.h
 DNSMASQOBJ = arp.o dbus.o domain.o lease.o outpacket.o rrfilter.o auth.o dhcp6.o edns0.o log.o poll.o slaac.o blockdata.o dhcp.o forward.o loop.o radv.o tables.o bpf.o dhcp-common.o helper.o netlink.o rfc1035.o tftp.o cache.o dnsmasq.o inotify.o network.o rfc2131.o util.o conntrack.o dnssec.o ipset.o option.o rfc3315.o crypto.o

api.c

@@ -380,20 +380,28 @@ void getTopClients(char *client_message, int *sock)
 		validate_access("clients", j, true, __LINE__, __FUNCTION__, __FILE__);
 
 		// Skip this client if there is a filter on it
-		if(excludeclients != NULL && insetupVarsArray(clients[j].ip))
+		if(excludeclients != NULL &&
+			(insetupVarsArray(clients[j].ip) || insetupVarsArray(clients[j].name)))
 			continue;
 
-		// Hidden domain, probably due to privacy level. Skip this in the top lists
+		// Hidden client, probably due to privacy level. Skip this in the top lists
 		if(strcmp(clients[j].ip, "0.0.0.0") == 0)
 			continue;
 
+		// Only return name if available
+		char *name;
+		if(clients[j].name != NULL)
+			name = clients[j].name;
+		else
+			name = "";
+
 		// Return this client if either
 		// - "withzero" option is set, and/or
 		// - the client made at least one query within the most recent 24 hours
 		if(includezeroclients || clients[j].count > 0)
 		{
 			if(istelnet[*sock])
-				ssend(*sock,"%i %i %s\n",n,clients[j].count,clients[j].ip);
+				ssend(*sock,"%i %i %s %s\n",n,clients[j].count,clients[j].ip,name);
 			else
 			{
 				if(!pack_str32(*sock, "") || !pack_str32(*sock, clients[j].ip))
@@ -437,7 +445,8 @@ void getForwardDestinations(char *client_message, int *sock)
 		}
 	}
 
-	if(sort) {
+	if(sort)
+	{
 		// Add "local " forward destination
 		temparray[counters.forwarded][0] = counters.forwarded;
 		temparray[counters.forwarded][1] = counters.cached + counters.blocked;
@@ -451,7 +460,7 @@ void getForwardDestinations(char *client_message, int *sock)
 	// Loop over available forward destinations
 	for(i=0; i < min(counters.forwarded+1, 10); i++)
 	{
-		char *ip;
+		char *ip, *name;
 		float percentage = 0.0f;
 
 		// Get sorted indices
@@ -465,6 +474,7 @@ void getForwardDestinations(char *client_message, int *sock)
 		if(j == counters.forwarded)
 		{
 			ip = strdup("local");
+			name = ip;
 
 			if(totalqueries > 0)
 				// Whats the percentage of (cached + blocked) queries on the total amount of queries?
@@ -477,6 +487,12 @@ void getForwardDestinations(char *client_message, int *sock)
 			validate_access("forwarded", j, true, __LINE__, __FUNCTION__, __FILE__);
 			ip = forwarded[j].ip;
 
+			// Only return name if available
+			if(forwarded[j].name != NULL)
+				name = forwarded[j].name;
+			else
+				name = "";
+
 			// Math explanation:
 			// A single query may result in requests being forwarded to multiple destinations
 			// Hence, in order to be able to give percentages here, we have to normalize the
@@ -503,7 +519,7 @@ void getForwardDestinations(char *client_message, int *sock)
 		if(percentage > 0.0f)
 		{
 			if(istelnet[*sock])
-				ssend(*sock, "%i %.2f %s\n", i, percentage, ip);
+				ssend(*sock, "%i %.2f %s %s\n", i, percentage, ip, name);
 			else
 			{
 				if(!pack_str32(*sock, "") || !pack_str32(*sock, ip))
@@ -515,7 +531,10 @@ void getForwardDestinations(char *client_message, int *sock)
 
 		// Free previously allocated memory only if we allocated it
 		if(allocated)
+		{
 			free(ip);
+			//free(name); // This is just the same as ip
+		}
 	}
 
 	if(debugclients)
@@ -681,12 +700,18 @@ void getAllQueries(char *client_message, int *sock)
 		if(filterclientname)
 		{
 			// Skip if client name and IP are not identical with what the user wants to see
-			if(strcmp(clients[queries[i].clientID].ip, clientname) != 0)
+			if(strcmp(clients[queries[i].clientID].ip,   clientname) != 0 &&
+			   strcmp(clients[queries[i].clientID].name, clientname) != 0)
 				continue;
 		}
 
 		char *domain = domains[queries[i].domainID].domain;
-		char *client = clients[queries[i].clientID].ip;
+		char *client;
+		if(clients[queries[i].clientID].name != NULL &&
+		   strlen(clients[queries[i].clientID].name) > 0)
+			client = clients[queries[i].clientID].name;
+		else
+			client = clients[queries[i].clientID].ip;
 
 		unsigned long delay = queries[i].response;
 		// Check if received (delay should be smaller than 30min)
@@ -967,7 +992,8 @@ void getClientsOverTime(int *sock)
 		{
 			validate_access("clients", i, true, __LINE__, __FUNCTION__, __FILE__);
 			// Check if this client should be skipped
-			if(insetupVarsArray(clients[i].ip))
+			if(insetupVarsArray(clients[i].ip) ||
+			   insetupVarsArray(clients[i].name))
 				skipclient[i] = true;
 		}
 	}
@@ -1039,7 +1065,8 @@ void getClientNames(int *sock)
 		{
 			validate_access("clients", i, true, __LINE__, __FUNCTION__, __FILE__);
 			// Check if this client should be skipped
-			if(insetupVarsArray(clients[i].ip))
+			if(insetupVarsArray(clients[i].ip) ||
+			   insetupVarsArray(clients[i].name))
 				skipclient[i] = true;
 		}
 	}
@@ -1051,8 +1078,14 @@ void getClientNames(int *sock)
 		if(skipclient[i])
 			continue;
 
+		char *client;
+		if(clients[i].name != NULL && strlen(clients[i].name) > 0)
+			client = clients[i].name;
+		else
+			client = clients[i].ip;
+
 		if(istelnet[*sock])
-			ssend(*sock, "%i %i %s\n", i, clients[i].count, clients[i].ip);
+			ssend(*sock, "%i %i %s\n", i, clients[i].count, client);
 		else {
 			if(!pack_str32(*sock, "") || !pack_str32(*sock, clients[i].ip))
 				return;

database.c

@@ -555,6 +555,10 @@ void *DB_thread(void *val)
 			// Update lastDBsave timer
 			lastDBsave = time(NULL) - time(NULL)%config.DBinterval;
 
+			// This has to be run outside of the thread locks
+			// to prevent locking the resolver
+			resolveNewClients();
+
 			// Lock FTL's data structure, since it is
 			// likely that it will be changed here
 			enable_thread_lock();

datastructure.c

@@ -111,6 +111,12 @@ int findForwardID(const char * forward, bool count)
 	forwarded[forwardID].ip = strdup(forward);
 	memory.forwardedips += (strlen(forward) + 1) * sizeof(char);
 	forwarded[forwardID].failed = 0;
+	// Initialize forward hostname
+	// Due to the nature of us being the resolver,
+	// the actual resolving of the host name has
+	// to be done separately to be non-blocking
+	forwarded[forwardID].new = true;
+	forwarded[forwardID].name = NULL;
 	// Increase counter by one
 	counters.forwarded++;
 
@@ -191,6 +197,12 @@ int findClientID(const char *client)
 	// Store client IP - no need to check for NULL here as it doesn't harm
 	clients[clientID].ip = strdup(client);
 	memory.clientips += (strlen(client) + 1) * sizeof(char);
+	// Initialize client hostname
+	// Due to the nature of us being the resolver,
+	// the actual resolving of the host name has
+	// to be done separately to be non-blocking
+	clients[clientID].new = true;
+	clients[clientID].name = NULL;
 	// Increase counter by one
 	counters.clients++;
 

gc.c

@@ -166,6 +166,11 @@ void *GC_thread(void *val)
 
 			// Release thread lock
 			disable_thread_lock();
+
+			// Reresolve client hostnames to account for changes
+			// Have to this outside of the thread lock
+			// to prevent locking of the resolver
+			reresolveHostnames();
 		}
 		sleepms(100);
 	}

resolve.c

@@ -0,0 +1,128 @@
+/* Pi-hole: A black hole for Internet advertisements
+*  (c) 2017 Pi-hole, LLC (https://pi-hole.net)
+*  Network-wide ad blocking via your own hardware.
+*
+*  FTL Engine
+*  DNS Client Implementation
+*
+*  This file is copyright under the latest version of the EUPL.
+*  Please see LICENSE file for your rights under this license. */
+
+#include "FTL.h"
+
+char *resolveHostname(const char *addr)
+{
+	// Get host name
+	struct hostent *he = NULL;
+	char *hostname = NULL;;
+	bool IPv6 = false;
+
+	// Check if this is a hidden client
+	// if so, return "hidden" as hostname
+	if(strcmp(addr, "0.0.0.0") == 0)
+	{
+		hostname = strdup("hidden");
+		//if(hostname == NULL) return NULL;
+		return hostname;
+	}
+
+	// Test if we want to resolve an IPv6 address
+	if(strstr(addr,":") != NULL)
+	{
+		IPv6 = true;
+	}
+
+	if(IPv6 && config.resolveIPv6) // Resolve IPv6 address only if requested
+	{
+		struct in6_addr ipaddr;
+		inet_pton(AF_INET6, addr, &ipaddr);
+		he = gethostbyaddr(&ipaddr, sizeof ipaddr, AF_INET6);
+	}
+	else if(!IPv6 && config.resolveIPv4) // Resolve IPv4 address only if requested
+	{
+		struct in_addr ipaddr;
+		inet_pton(AF_INET, addr, &ipaddr);
+		he = gethostbyaddr(&ipaddr, sizeof ipaddr, AF_INET);
+	}
+
+	if(he == NULL)
+	{
+		// No hostname found
+		hostname = strdup("");
+		//if(hostname == NULL) return NULL;
+	}
+	else
+	{
+		// Return hostname copied to new memory location
+		hostname = strdup(he->h_name);
+		if(hostname == NULL) return NULL;
+		// Convert hostname to lower case
+		strtolower(hostname);
+	}
+	return hostname;
+}
+
+// This routine is run *after* garbage cleaning (default interval is once per hour)
+// to account for possibly updated hostnames
+void reresolveHostnames(void)
+{
+	int clientID;
+	for(clientID = 0; clientID < counters.clients; clientID++)
+	{
+		// Memory validation
+		validate_access("clients", clientID, true, __LINE__, __FUNCTION__, __FILE__);
+
+		// Process this client only if it has at least one active query in the log
+		if(clients[clientID].count < 1)
+			continue;
+
+		// Get client hostname
+		char *hostname = resolveHostname(clients[clientID].ip);
+		if(strlen(hostname) > 0)
+		{
+			// Delete possibly already existing hostname pointer before storing new data
+			if(clients[clientID].name != NULL)
+			{
+				free(clients[clientID].name);
+				clients[clientID].name = NULL;
+			}
+
+			// Store client hostname
+			clients[clientID].name = strdup(hostname);
+		}
+		free(hostname);
+	}
+}
+
+// This routine is run *before* saving to the database (default interval is once per minute)
+// to account for new clients (and forward destinations)
+void resolveNewClients(void)
+{
+	int i;
+	for(i = 0; i < counters.clients; i++)
+	{
+		// Memory validation
+		validate_access("clients", i, true, __LINE__, __FUNCTION__, __FILE__);
+
+		// Only try to resolve new clients
+		// Note that it can happen that we are not able to find hostnames but we don't
+		// want to try to resolve them every minute in this case.
+		if(clients[i].new)
+		{
+			clients[i].name = resolveHostname(clients[i].ip);
+			clients[i].new = false;
+		}
+	}
+	for(i = 0; i < counters.forwarded; i++)
+	{
+		// Memory validation
+		validate_access("forwarded", i, true, __LINE__, __FUNCTION__, __FILE__);
+
+		// Only try to resolve new forward destinations
+		if(forwarded[i].new)
+		{
+			forwarded[i].name = resolveHostname(forwarded[i].ip);
+			forwarded[i].new = false;
+		}
+	}
+}

routines.h

@@ -100,3 +100,7 @@ int main_dnsmasq(int argc, char **argv);
 
 // signals.c
 void handle_signals(void);
+
+// resolve.c
+void resolveNewClients(void);
+void reresolveHostnames(void);

setupVars.c

@@ -165,6 +165,11 @@ void clearSetupVarsArray(void)
 bool insetupVarsArray(char * str)
 {
 	int i;
+	// Check for possible NULL pointer
+	// (this is valid input, e.g. if clients[i].name is unspecified)
+	if(str == NULL)
+		return false;
+
 	// Loop over all entries in setupVarsArray
 	for (i = 0; i < setupVarsElements; ++i)
 		if(setupVarsArray[i][0] == '*')