Merge pull request #1111 from pi-hole/new/reply_pihole_hostname

Handle pi.hole and hostname interface-dependent

src/daemon.c

@@ -22,6 +22,8 @@
 #include "database/common.h"
 // destroy_shmem()
 #include "shmem.h"
+// uname()
+#include <sys/utsname.h>
 // killed
 #include "signals.h"
 
@@ -141,6 +143,30 @@ char *getUserName(void)
 	return name;
 }
 
+// "man 7 hostname" says:
+//
+//     Each element of the hostname must be from 1 to 63 characters long and the
+//     entire hostname, including the dots, can be at most 253 characters long.
+//
+//     Valid characters for hostnames are ASCII(7) letters from a to z, the
+//     digits from 0 to 9, and the hyphen (-). A hostname may not start with a
+//     hyphen.
+#define HOSTNAMESIZE 256
+static char nodename[HOSTNAMESIZE] = { 0 };
+const char *hostname(void)
+{
+	// Ask kernel for node name if not known
+	// This is equivalent to "uname -n"
+	if(nodename[0] == '\0')
+	{
+		struct utsname buf;
+		if(uname(&buf) == 0)
+			strncpy(nodename, buf.nodename, HOSTNAMESIZE);
+		nodename[HOSTNAMESIZE-1] = '\0';
+	}
+	return nodename;
+}
+
 void delay_startup(void)
 {
 	// Exit early if not sleeping

src/daemon.h

@@ -16,6 +16,7 @@ extern pthread_t threads[THREADS_MAX];
 void go_daemon(void);
 void savepid(void);
 char *getUserName(void);
+const char *hostname(void);
 void delay_startup(void);
 bool is_fork(const pid_t mpid, const pid_t pid) __attribute__ ((const));
 void cleanup(const int ret);

src/datastructure.h

@@ -102,7 +102,7 @@ ASSERT_SIZEOF(domainsData, 24, 16, 16);
 typedef struct {
 	unsigned char magic;
 	enum domain_client_status blocking_status;
-	unsigned char force_reply;
+	enum reply_type force_reply;
 	enum query_types query_type;
 	int domainID;
 	int clientID;

src/dnsmasq_interface.c

@@ -58,7 +58,7 @@ static void query_blocked(queriesData* query,
 
 // Static blocking metadata
 static union all_addr null_addrp = {{ 0 }};
-static unsigned char force_next_DNS_reply = 0u;
+static enum reply_type force_next_DNS_reply = REPLY_UNKNOWN;
 
 // Adds debug information to the regular pihole.log file
 char debug_dnsmasq_lines = 0;
@@ -82,10 +82,28 @@ void FTL_iface(const int ifidx, const struct irec *ifaces)
 
 	// Copy overwrite addresses if configured via REPLY_ADDR4 and/or REPLY_ADDR6 settings
 	if(config.reply_addr.overwrite_v4)
+	{
 		memcpy(&next_iface.addr4, &config.reply_addr.v4, sizeof(config.reply_addr.v4));
+
+		if(config.debug & DEBUG_NETWORKING)
+		{
+			char buffer[ADDRSTRLEN+1] = { 0 };
+			inet_ntop(AF_INET, &next_iface.addr4, buffer, ADDRSTRLEN);
+			logg("Interface (%d) %s OVERWRITES IPv4 address %s", ifidx, next_iface.name, buffer);
+		}
+	}
 	if(config.reply_addr.overwrite_v6)
+	{
 		memcpy(&next_iface.addr6, &config.reply_addr.v6, sizeof(config.reply_addr.v6));
 
+		if(config.debug & DEBUG_NETWORKING)
+		{
+			char buffer[ADDRSTRLEN+1] = { 0 };
+			inet_ntop(AF_INET6, &next_iface.addr6, buffer, ADDRSTRLEN);
+			logg("Interface (%d) %s OVERWRITES IPv6 address %s", ifidx, next_iface.name, buffer);
+		}
+	}
+
 	// Use dummy when interface record is not available
 	next_iface.name[0] = '-';
 	next_iface.name[1] = '\0';
@@ -396,8 +414,8 @@ static bool _FTL_check_blocking(int queryID, int domainID, int clientID, const c
 			// Truncate "_esni." from queried domain if the parenting domain was the reason for blocking this query
 			blockedDomain = domainstr + 6u;
 			// Force next DNS reply to be NXDOMAIN for _esni.* queries
-			force_next_DNS_reply = NXDOMAIN;
-			dns_cache->force_reply = NXDOMAIN;
+			force_next_DNS_reply = REPLY_NXDOMAIN;
+			dns_cache->force_reply = REPLY_NXDOMAIN;
 		}
 	}
 
@@ -633,9 +651,24 @@ bool _FTL_new_query(const unsigned int flags, const char *name,
 		return false;
 	}
 
-	// If domain is "pi.hole" we skip this query
-	if(strcasecmp(name, "pi.hole") == 0)
-		return false;
+	// If domain is "pi.hole" or the local hostname we skip analyzing this query
+	// and, instead, immediately reply with the IP address
+	if(strcasecmp(name, "pi.hole") == 0 || strcasecmp(name, hostname()) == 0)
+	{
+		if(querytype == TYPE_A || querytype == TYPE_AAAA || querytype == TYPE_ANY)
+		{
+			// "Block" this query by sending the interface IP address
+			force_next_DNS_reply = REPLY_IP;
+			if(config.debug & DEBUG_QUERIES)
+				logg("Replying to %s with interface-local IP address", name);
+			return true;
+		}
+		else
+		{
+			// Don't block this query
+			return false;
+		}
+	}
 
 	// Convert domain to lower case
 	char *domainString = strdup(name);
@@ -660,7 +693,7 @@ bool _FTL_new_query(const unsigned int flags, const char *name,
 		inet_ntop(family,
 		          family == AF_INET ?
 		             (union mysockaddr*)&addr->in.sin_addr :
-				(union mysockaddr*)&addr->in6.sin6_addr,
+		             (union mysockaddr*)&addr->in6.sin6_addr,
 		          clientIP, ADDRSTRLEN);
 	}
 
@@ -703,7 +736,7 @@ bool _FTL_new_query(const unsigned int flags, const char *name,
 		}
 
 		// Block this query
-		force_next_DNS_reply = REFUSED;
+		force_next_DNS_reply = REPLY_REFUSED;
 
 		// Do not further process this query, Pi-hole has never seen it
 		unlock_shm();
@@ -868,19 +901,21 @@ void _FTL_get_blocking_metadata(union all_addr **addrp, unsigned int *flags, con
 	// 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.
-	if(force_next_DNS_reply == NXDOMAIN)
+	if(force_next_DNS_reply == REPLY_NXDOMAIN)
 	{
 		*flags = F_NXDOMAIN;
+
 		// Reset DNS reply forcing
-		force_next_DNS_reply = 0u;
+		force_next_DNS_reply = REPLY_UNKNOWN;
 		return;
 	}
-	else if(force_next_DNS_reply == REFUSED)
+	else if(force_next_DNS_reply == REPLY_REFUSED)
 	{
 		// Empty flags result in REFUSED
 		*flags = 0;
+
 		// Reset DNS reply forcing
-		force_next_DNS_reply = 0u;
+		force_next_DNS_reply = REPLY_UNKNOWN;
 		return;
 	}
 
@@ -894,18 +929,35 @@ void _FTL_get_blocking_metadata(union all_addr **addrp, unsigned int *flags, con
 	if(*flags & F_IPV6)
 	{
 		// Pass blocking IPv6 address
-		if(config.blockingmode == MODE_IP)
+		if(config.blockingmode == MODE_IP ||
+		   force_next_DNS_reply == REPLY_IP)
+		{
 			*addrp = &next_iface.addr6;
+		}
 		else
+		{
 			*addrp = &null_addrp;
+		}
+
+		// Reset reply forcing
+		force_next_DNS_reply = REPLY_UNKNOWN;
 	}
 	else
 	{
 		// Pass blocking IPv4 address
-		if(config.blockingmode == MODE_IP || config.blockingmode == MODE_IP_NODATA_AAAA)
+		if(config.blockingmode == MODE_IP ||
+		   config.blockingmode == MODE_IP_NODATA_AAAA ||
+		   force_next_DNS_reply == REPLY_IP)
+		{
 			*addrp = &next_iface.addr4;
+		}
 		else
+		{
 			*addrp = &null_addrp;
+		}
+
+		// Reset reply forcing
+		force_next_DNS_reply = REPLY_UNKNOWN;
 	}
 
 	if(config.blockingmode == MODE_NX)
@@ -1086,6 +1138,16 @@ void _FTL_reply(const unsigned int flags, const char *name, const union all_addr
 	// Lock shared memory
 	lock_shm();
 
+	// Save status in corresponding query identified by dnsmasq's ID
+	const int queryID = findQueryID(id);
+	if(queryID < 0)
+	{
+		// This may happen e.g. if the original query was "pi.hole"
+		if(config.debug & DEBUG_QUERIES) logg("FTL_reply(): Query %i has not been found", id);
+		unlock_shm();
+		return;
+	}
+
 	// Determine returned result if available
 	char dest[ADDRSTRLEN]; dest[0] = '\0';
 	if(addr)
@@ -1128,18 +1190,8 @@ void _FTL_reply(const unsigned int flags, const char *name, const union all_addr
 	struct timeval response;
 	gettimeofday(&response, 0);
 
-	// Save status in corresponding query identified by dnsmasq's ID
-	const int i = findQueryID(id);
-	if(i < 0)
-	{
-		// This may happen e.g. if the original query was "pi.hole"
-		if(config.debug & DEBUG_QUERIES) logg("FTL_reply(): Query %i has not been found", id);
-		unlock_shm();
-		return;
-	}
-
 	// Get query pointer
-	queriesData* query = getQuery(i, true);
+	queriesData* query = getQuery(queryID, true);
 
 	// Check if reply time is still unknown
 	// We only process the first reply in here
@@ -1708,7 +1760,7 @@ static void query_set_reply(const unsigned int flags, const union all_addr *addr
                             queriesData* query, const struct timeval response)
 {
 	// Iterate through possible values
-	if(flags & F_NEG || force_next_DNS_reply == NXDOMAIN)
+	if(flags & F_NEG || force_next_DNS_reply == REPLY_NXDOMAIN)
 	{
 		if(flags & F_NXDOMAIN)
 			// NXDOMAIN
@@ -1726,10 +1778,10 @@ static void query_set_reply(const unsigned int flags, const union all_addr *addr
 	else if(flags & F_RRNAME)
 		// TXT query
 		query->reply = REPLY_RRNAME;
-	else if((flags & F_RCODE && addr != NULL) || force_next_DNS_reply == REFUSED)
+	else if((flags & F_RCODE && addr != NULL) || force_next_DNS_reply == REPLY_REFUSED)
 	{
 		if((addr != NULL && addr->log.rcode == REFUSED)
-		   || force_next_DNS_reply == REFUSED )
+		   || force_next_DNS_reply == REPLY_REFUSED )
 		{
 			// REFUSED query
 			query->reply = REPLY_REFUSED;

src/main.c

@@ -47,7 +47,7 @@ int main (int argc, char* argv[])
 	// Try to open FTL log
 	init_FTL_log();
 	timer_start(EXIT_TIMER);
-	logg("########## FTL started! ##########");
+	logg("########## FTL started on %s! ##########", hostname());
 	log_FTL_version(false);
 
 	// Catch signals not handled by dnsmasq

src/main.h

@@ -12,7 +12,7 @@
 
 int main_dnsmasq(int argc, const char ** argv);
 
-extern char * username;
+extern char *username;
 extern bool startup;
 
 #endif //MAIN_H