Merge pull request #2120 from pi-hole/debug/no_fork

Enable debug mode when debugger is detected

src/args.c

@@ -80,7 +80,7 @@ extern int sqlite3_shell_main(int argc, char **argv);
 // defined in database/sqlite3_rsync.c
 extern int sqlite3_rsync_main(int argc, char **argv);
 
-bool dnsmasq_debug = false;
+bool debug_mode = false;
 bool daemonmode = true, cli_mode = false;
 int argc_dnsmasq = 0;
 const char** argv_dnsmasq = NULL;
@@ -611,7 +611,7 @@ void parse_args(int argc, char *argv[])
 		if(strcmp(argv[i], "lua") == 0 ||
 		   strcmp(argv[i], "--lua") == 0)
 		{
-			exit(run_lua_interpreter(argc - i, &argv[i], dnsmasq_debug));
+			exit(run_lua_interpreter(argc - i, &argv[i], debug_mode));
 		}
 
 		// Expose internal lua compiler
@@ -729,7 +729,7 @@ void parse_args(int argc, char *argv[])
 			argv_dnsmasq = calloc(argc_dnsmasq, sizeof(const char*));
 			argv_dnsmasq[0] = "";
 
-			if(dnsmasq_debug)
+			if(debug_mode)
 			{
 				argv_dnsmasq[1] = "-d";
 				argv_dnsmasq[2] = "--log-debug";
@@ -740,7 +740,7 @@ void parse_args(int argc, char *argv[])
 				argv_dnsmasq[2] = "";
 			}
 
-			if(dnsmasq_debug)
+			if(debug_mode)
 			{
 				printf("dnsmasq options: [0]: %s\n", argv_dnsmasq[0]);
 				printf("dnsmasq options: [1]: %s\n", argv_dnsmasq[1]);
@@ -751,7 +751,7 @@ void parse_args(int argc, char *argv[])
 			while(i < argc)
 			{
 				argv_dnsmasq[j++] = strdup(argv[i++]);
-				if(dnsmasq_debug)
+				if(debug_mode)
 					printf("dnsmasq options: [%i]: %s\n", j-1, argv_dnsmasq[j-1]);
 			}
 
@@ -764,11 +764,11 @@ void parse_args(int argc, char *argv[])
 		if(strcmp(argv[i], "d") == 0 ||
 		   strcmp(argv[i], "debug") == 0)
 		{
-			dnsmasq_debug = true;
+			debug_mode = true;
 			daemonmode = false;
 			ok = true;
 
-			// Replace "-k" by "-d" (dnsmasq_debug mode implies nofork)
+			// Replace "-k" by "-d" (debug_mode mode implies nofork)
 			argv_dnsmasq[1] = "-d";
 		}
 
@@ -951,9 +951,9 @@ void parse_args(int argc, char *argv[])
 			// Enable stdout printing
 			cli_mode = true;
 			if(argc == i + 2)
-				exit(regex_test(dnsmasq_debug, quiet, argv[i + 1], NULL));
+				exit(regex_test(debug_mode, quiet, argv[i + 1], NULL));
 			else if(argc == i + 3)
-				exit(regex_test(dnsmasq_debug, quiet, argv[i + 1], argv[i + 2]));
+				exit(regex_test(debug_mode, quiet, argv[i + 1], argv[i + 2]));
 			else
 			{
 				printf("pihole-FTL: invalid option -- '%s' need either one or two parameters\nTry '%s --help' for more information\n", argv[i], argv[0]);

src/args.h

@@ -12,7 +12,7 @@
 
 void parse_args(int argc, char *argv[]);
 
-extern bool daemonmode, cli_mode, dnsmasq_debug;
+extern bool daemonmode, cli_mode;
 extern int argc_dnsmasq;
 extern const char ** argv_dnsmasq;
 

src/dnsmasq/dnsmasq.h

@@ -293,6 +293,11 @@ struct event_desc {
 #define option_val(x) ((1u) << ((x) % OPTION_BITS))
 #define option_bool(x) (option_var(x) & option_val(x))
 
+/***** Pi-hole modification *****/
+#define option_set(x) (option_var(x) |= option_val(x))
+#define option_clear(x) (option_var(x) &= ~option_val(x))
+/********************************/
+
 /* extra flags for my_syslog, we use facilities since they are known 
    not to occupy the same bits as priorities, no matter how syslog.h is set up. 
    MS_DEBUG messages are suppressed unless --log-debug is set. */

src/dnsmasq_interface.c

@@ -56,6 +56,8 @@
 #include "main.h"
 // ntp_server_start()
 #include "ntp/ntp.h"
+// get_process_name()
+#include "procps.h"
 
 // Private prototypes
 static void print_flags(const unsigned int flags);
@@ -3386,7 +3388,7 @@ void FTL_forwarding_retried(const struct server *serv, const int oldID, const in
 volatile atomic_flag worker_already_terminating = ATOMIC_FLAG_INIT;
 void FTL_TCP_worker_terminating(bool finished)
 {
-	if(dnsmasq_debug)
+	if(get_dnsmasq_debug())
 	{
 		// Nothing to be done here, forking does not happen in debug mode
 		return;
@@ -3431,7 +3433,7 @@ void FTL_TCP_worker_terminating(bool finished)
 // to ending up with a corrupted database.
 void FTL_TCP_worker_created(const int confd)
 {
-	if(dnsmasq_debug)
+	if(get_dnsmasq_debug())
 	{
 		// Nothing to be done here, TCP worker forking does not happen
 		// in debug mode
@@ -3765,3 +3767,50 @@ void FTL_connection_error(const char *reason, const union mysockaddr *addr)
 			free(server);
 	}
 }
+
+/**
+ * @brief Retrieves the debug status of dnsmasq.
+ *
+ * @return true if the debug option is enabled, false otherwise.
+ */
+bool __attribute__ ((pure)) get_dnsmasq_debug(void)
+{
+	return option_bool(OPT_DEBUG);
+}
+
+static bool enabled = false;
+/**
+ * @brief Set the dnsmasq debug mode based on the enable flag and process ID.
+ *
+ * This function enables or disables the dnsmasq debug mode. When enabling,
+ * it logs the process ID and name, sets the debug option, and marks the
+ * debug mode as enabled. When disabling, it logs the detachment and clears
+ * the debug option. If the debug mode is already enabled, it does nothing.
+ *
+ * @param enable A boolean flag indicating whether to enable or disable debug mode.
+ * @param pid The process ID of the process to attach or detach the debugger.
+ */
+void set_dnsmasq_debug(const bool enable, const pid_t pid)
+{
+	// Get debugger process' name
+	char name[PROC_PATH_SIZ] = "???";
+	get_process_name(pid, name);
+
+	// Only enable or disable if the debug mode is not already set
+	if(enable && !get_dnsmasq_debug())
+	{
+		// Enable debug mode
+		log_info("Debugger attached (%d: %s), entering dnsmasq debug mode",
+		         pid, name);
+		option_set(OPT_DEBUG);
+		enabled = true;
+
+		return;
+	}
+	else if(enabled)
+	{
+		// Disable debug mode
+		log_info("Debugger detached, leaving dnsmasq debug mode");
+		option_clear(OPT_DEBUG);
+	}
+}

src/dnsmasq_interface.h

@@ -51,6 +51,8 @@ bool FTL_unlink_DHCP_lease(const char *ipaddr, const char **hint);
 
 void FTL_connection_error(const char *reason, const union mysockaddr *addr);
 
+bool get_dnsmasq_debug(void) __attribute__ ((pure));
+
 // defined in src/dnsmasq/cache.c
 extern char *querystr(char *desc, unsigned short type);
 

src/gc.c

@@ -233,6 +233,8 @@ static void recycle(void)
 
 		log_debug(DEBUG_GC, "Recycled %u clients, %u domains, and %u cache records (scanned %u queries)",
 		          clients_recycled, domains_recycled, cache_recycled, counters->queries);
+
+		dump_strings();
 	}
 }
 
@@ -528,8 +530,11 @@ static bool check_files_on_same_device(const char *path1, const char *path2)
 	return s1.st_dev == s2.st_dev;
 }
 
+static bool is_debugged = false;
 void *GC_thread(void *val)
 {
+	(void)val; // Mark parameter as unused
+
 	// Set thread name
 	prctl(PR_SET_NAME, thread_names[GC], 0, 0, 0);
 
@@ -636,6 +641,15 @@ void *GC_thread(void *val)
 		if(killed)
 			break;
 
+		// Check if FTL is being debugged and set dnsmasq's debug mode
+		// accordingly
+		const pid_t dpid = debugger();
+		if((dpid > 0) != is_debugged)
+		{
+			is_debugged = dpid > 0;
+			set_dnsmasq_debug(is_debugged, dpid);
+		}
+
 		// Sleep for the remaining time of the interval (if any)
 		const double time_end = double_time();
 		const double time_diff = time_end - time_start;

src/gc.h

@@ -10,8 +10,14 @@
 #ifndef GC_H
 #define GC_H
 
+#include <stdbool.h>
+#include <time.h>
+
 void *GC_thread(void *val);
 void runGC(const time_t now, time_t *lastGCrun, const bool flush);
 time_t get_rate_limit_turnaround(const unsigned int rate_limit_count);
 
+// Defined in src/dnsmasq_interface.c
+void set_dnsmasq_debug(const bool debug, const pid_t pid);
+
 #endif //GC_H

src/lookup-table.c

@@ -75,8 +75,8 @@ static inline int cmp_hash(const uint32_t a, const uint32_t b)
  * found element or NULL (!) if the element is not found which provides no
  * information about the position where the element would need to be inserted.
  */
-static bool binsearch(const struct lookup_table *base, const uint32_t hash,
-                      size_t size, const struct lookup_table **try)
+static bool binsearch(struct lookup_table *base, const uint32_t hash,
+                      size_t size, struct lookup_table **try)
 {
 	// Initialize the base pointer to the start of the array
 	*try = base;
@@ -207,7 +207,7 @@ bool lookup_insert(const enum memory_type type, const unsigned int id, const uin
 	// Find the correct position in the lookup_table array
 	// We do not check the return value as we are inserting a new element
 	// and don't care if elements with the same hash value exist already
-	const struct lookup_table *try = table;
+	struct lookup_table *try = table;
 	binsearch(table, hash, *size, &try);
 
 	// Calculate the position where the element would be inserted
@@ -217,7 +217,7 @@ bool lookup_insert(const enum memory_type type, const unsigned int id, const uin
 	// one position to the right to make space for the new element
 	// Don't move anything if the element is added at the end of the array
 	if(pos < *size)
-		memmove((void*)(try + 1), try, (*size - pos) * sizeof(struct lookup_table));
+		memmove(try + 1, try, (*size - pos) * sizeof(struct lookup_table));
 
 	// Prepare the new lookup_table element and insert it at the correct
 	// position
@@ -253,7 +253,7 @@ bool lookup_remove(const enum memory_type type, const unsigned int id, const uin
 		return false;
 
 	// Find the correct position in the lookup_table array
-	const struct lookup_table *try = NULL;
+	struct lookup_table *try = NULL;
 	if(!binsearch(table, hash, *size, &try))
 	{
 		// The element is not in the array
@@ -283,13 +283,14 @@ bool lookup_remove(const enum memory_type type, const unsigned int id, const uin
 			// one position to the left to remove the element
 			// Don't move anything if the element is removed from the end of the array
 			if(pos < *size - 1)
-				memmove(&table[pos], &table[pos + 1], (*size - pos - 1) * sizeof(struct lookup_table));
+				memmove(table + pos, table + pos + 1,
+				        (*size - pos - 1) * sizeof(struct lookup_table));
 
 			// Decrease the number of elements in the array
 			(*size)--;
 
 			// Zero out the memory of the removed element
-			memset(&table[*size], 0, sizeof(struct lookup_table));
+			memset(table + *size, 0, sizeof(struct lookup_table));
 
 			return true;
 		}
@@ -332,7 +333,7 @@ bool lookup_find_id(const enum memory_type type, const uint32_t hash, const stru
 		return false;
 
 	// Find the correct position in the lookup_table array
-	const struct lookup_table *try = NULL;
+	struct lookup_table *try = NULL;
 	if(!binsearch(table, hash, *size, &try))
 		return false;
 

src/lua/ftl_lua.c

@@ -36,7 +36,7 @@
 #include "daemon.h"
 
 
-int run_lua_interpreter(const int argc, char **argv, bool dnsmasq_debug)
+int run_lua_interpreter(const int argc, char **argv, bool debug)
 {
 	if(argc == 1) // No arguments after this one
 		printf("Pi-hole FTL %s\n", get_FTL_version());
@@ -48,7 +48,7 @@ int run_lua_interpreter(const int argc, char **argv, bool dnsmasq_debug)
 	{
 		history_file = word.we_wordv[0];
 		const int ret_r = read_history(history_file);
-		if(dnsmasq_debug)
+		if(debug)
 		{
 			printf("Reading history ... ");
 			if(ret_r == 0)
@@ -60,7 +60,7 @@ int run_lua_interpreter(const int argc, char **argv, bool dnsmasq_debug)
 		// The history file may not exist, try to create an empty one in this case
 		if(ret_r == ENOENT)
 		{
-			if(dnsmasq_debug)
+			if(debug)
 			{
 				printf("Creating new history file: %s\n", history_file);
 			}
@@ -70,15 +70,15 @@ int run_lua_interpreter(const int argc, char **argv, bool dnsmasq_debug)
 		}
 	}
 #else
-	if(dnsmasq_debug)
+	if(debug)
 		printf("No readline available!\n");
 #endif
 	const int ret = lua_main(argc, argv);
 #if defined(LUA_USE_READLINE)
 	if(history_file != NULL)
 	{
 		const int ret_w = write_history(history_file);
-		if(dnsmasq_debug)
+		if(debug)
 		{
 			printf("Writing history ... ");
 			if(ret_w == 0)

src/lua/ftl_lua.h

@@ -15,7 +15,7 @@
 
 #define LUA_HISTORY_FILE "~/.pihole_lua_history"
 
-int run_lua_interpreter(const int argc, char **argv, bool dnsmasq_debug);
+int run_lua_interpreter(const int argc, char **argv, bool debug);
 int run_luac(const int argc, char **argv);
 
 int lua_main (int argc, char **argv);

src/procps.c

@@ -19,7 +19,6 @@
 #include "config/config.h"
 
 #define PROCESS_NAME   "pihole-FTL"
-#define PROC_PATH_SIZ  32
 
 // This function tries to obtain the process name of a given PID
 // It returns true on success, false otherwise and stores the process name in
@@ -28,7 +27,7 @@
 // to parse /proc/<pid>/comm. The latter is not guaranteed to be correct (e.g.
 // processes can easily change it themselves using prctl with PR_SET_NAME), but
 // it is better than nothing.
-static bool get_process_name(const pid_t pid, char name[PROC_PATH_SIZ])
+bool get_process_name(const pid_t pid, char name[PROC_PATH_SIZ])
 {
 	if(pid == 0)
 	{

src/procps.h

@@ -10,6 +10,13 @@
 
 #ifndef PROCPS_H
 #define PROCPS_H
+
+#include <stdbool.h>
+#include <sys/types.h>
+
+#define PROC_PATH_SIZ  32
+
+bool get_process_name(const pid_t pid, char name[PROC_PATH_SIZ]);
 bool another_FTL(void);
 
 struct proc_mem {