New logging facilities

7 files changed, 349 insertions, 242 deletions

diff --git a/src/config.c b/src/config.c
index d9397cc..a77c258 100644
--- a/src/config.c
+++ b/src/config.c
@@ -51,7 +51,10 @@ extern const fastd_method fastd_method_xsalsa20_poly1305;
 
 
 static void default_config(fastd_config *conf) {
-	conf->loglevel = LOG_INFO;
+	conf->log_stderr_level = -1;
+	conf->log_syslog_level = -1;
+	conf->log_syslog_ident = strdup("fastd");
+	conf->log_files = NULL;
 
 	conf->keepalive_interval = 60;
 	conf->peer_stale_time = 300;
@@ -135,6 +138,43 @@ bool fastd_config_method(fastd_context *ctx, fastd_config *conf, const char *nam
 	return true;
 }
 
+bool fastd_config_add_log_file(fastd_context *ctx, fastd_config *conf, const char *name, int level) {
+	char *name2 = strdup(name);
+	char *name3 = strdup(name);
+
+	char *dir = dirname(name2);
+	char *base = basename(name3);
+
+	char *oldcwd = get_current_dir_name();
+
+	if (!chdir(dir)) {
+		char *logdir = get_current_dir_name();
+
+		fastd_log_file *file = malloc(sizeof(fastd_log_file));
+		file->filename = malloc(strlen(logdir) + 1 + strlen(base) + 1);
+
+		strcpy(file->filename, logdir);
+		strcat(file->filename, "/");
+		strcat(file->filename, base);
+
+		file->level = level;
+
+		file->next = conf->log_files;
+		conf->log_files = file;
+
+		if(chdir(oldcwd))
+			pr_error(ctx, "can't chdir to `%s': %s", oldcwd, strerror(errno));
+	}
+	else {
+		pr_error(ctx, "change from directory `%s' to `%s' failed: %s", oldcwd, dir, strerror(errno));
+	}
+
+
+	free(name2);
+	free(name3);
+	return true;
+}
+
 static void read_peer_dir(fastd_context *ctx, fastd_config *conf, const char *dir) {
 	DIR *dirh = opendir(".");
 
@@ -334,7 +374,9 @@ static void count_peers(fastd_context *ctx, fastd_config *conf) {
 	OPTION(usage, "--help" OR "-h", "Shows this help text") \
 	OPTION(version, "--version" OR "-v", "Shows the fastd version") \
 	OPTION(option_daemon, "--daemon" OR "-d", "Runs fastd in the background") \
-	OPTION_ARG(option_log_level, "--log-level", "error|warn|info|verbose|debug", "Sets the log level; default is info") \
+	OPTION_ARG(option_log_level, "--log-level", "error|warn|info|verbose|debug", "Sets the stderr log level; default is info, if no alternative log destination ist configured") \
+	OPTION_ARG(option_syslog_level, "--syslog-level", "error|warn|info|verbose|debug", "Sets the log level for syslog output; default is not to use syslog") \
+	OPTION_ARG(option_syslog_ident, "--syslog-ident", "<ident>", "Sets the syslog identification; default is 'fastd'") \
 	OPTION_ARG(option_config, "--config" OR "-c", "<filename>", "Loads a config file") \
 	OPTION_ARG(option_config_peer, "--config-peer", "<filename>", "Loads a config file for a single peer") \
 	OPTION_ARG(option_config_peer_dir, "--config-peer-dir", "<dir>", "Loads all files from a directory as peer configs") \
@@ -390,24 +432,38 @@ static void version(fastd_context *ctx, fastd_config *conf) {
 	exit(0);
 }
 
-
-static void option_log_level(fastd_context *ctx, fastd_config *conf, const char *arg) {
+static int parse_log_level(fastd_context *ctx, const char *arg) {
 	if (!strcmp(arg, "fatal"))
-		conf->loglevel = LOG_FATAL;
+		return LOG_CRIT;
 	else if (!strcmp(arg, "error"))
-		conf->loglevel = LOG_ERROR;
+		return LOG_ERR;
 	else if (!strcmp(arg, "warn"))
-		conf->loglevel = LOG_WARN;
+		return LOG_WARNING;
 	else if (!strcmp(arg, "info"))
-		conf->loglevel = LOG_INFO;
+		return LOG_NOTICE;
 	else if (!strcmp(arg, "verbose"))
-		conf->loglevel = LOG_VERBOSE;
+		return LOG_INFO;
 	else if (!strcmp(arg, "debug"))
-		conf->loglevel = LOG_DEBUG;
+		return LOG_DEBUG;
 	else
 		exit_error(ctx, "invalid log level `%s'", arg);
 }
 
+
+
+static void option_log_level(fastd_context *ctx, fastd_config *conf, const char *arg) {
+	conf->log_stderr_level = parse_log_level(ctx, arg);
+}
+
+static void option_syslog_level(fastd_context *ctx, fastd_config *conf, const char *arg) {
+	conf->log_syslog_level = parse_log_level(ctx, arg);
+}
+
+static void option_syslog_ident(fastd_context *ctx, fastd_config *conf, const char *arg) {
+	free(conf->log_syslog_ident);
+	conf->log_syslog_ident = strdup(arg);
+}
+
 static void option_config(fastd_context *ctx, fastd_config *conf, const char *arg) {
 	if (!strcmp(arg, "-"))
 		arg = NULL;
@@ -599,6 +655,9 @@ void fastd_configure(fastd_context *ctx, fastd_config *conf, int argc, char *con
 		exit_error(ctx, "config error: unknown option `%s'; see --help for usage", argv[i]);
 	}
 
+	if (conf->log_stderr_level < 0 && conf->log_syslog_level < 0 && !conf->log_files)
+		conf->log_stderr_level = FASTD_DEFAULT_LOG_LEVEL;
+
 	if (conf->generate_key || conf->show_key)
 		return;
 
@@ -725,6 +784,13 @@ void fastd_config_release(fastd_context *ctx, fastd_config *conf) {
 
 	fastd_string_stack_free(conf->peer_dirs);
 
+	while (conf->log_files) {
+		fastd_log_file *next = conf->log_files->next;
+		free(conf->log_files->filename);
+		free(conf->log_files);
+		conf->log_files = next;
+	}
+
 	free(conf->ifname);
 	free(conf->secret);
 	free(conf->on_up);
@@ -736,4 +802,5 @@ void fastd_config_release(fastd_context *ctx, fastd_config *conf) {
 	free(conf->on_disestablish);
 	free(conf->on_disestablish_dir);
 	free(conf->protocol_config);
+	free(conf->log_syslog_ident);
 }
diff --git a/src/config.l b/src/config.l
index 963a05b..4f7dd7f 100644
--- a/src/config.l
+++ b/src/config.l
@@ -80,6 +80,9 @@ peers		{ UPDATE_LOCATION; return TOK_PEERS; }
 from		{ UPDATE_LOCATION; return TOK_FROM; }
 log		{ UPDATE_LOCATION; return TOK_LOG; }
 level 		{ UPDATE_LOCATION; return TOK_LEVEL; }
+syslog		{ UPDATE_LOCATION; return TOK_SYSLOG; }
+stderr		{ UPDATE_LOCATION; return TOK_STDERR; }
+to		{ UPDATE_LOCATION; return TOK_TO; }
 fatal		{ UPDATE_LOCATION; return TOK_FATAL; }
 error		{ UPDATE_LOCATION; return TOK_ERROR; }
 warn		{ UPDATE_LOCATION; return TOK_WARN; }
diff --git a/src/config.y b/src/config.y
index e283630..ec2aabe 100644
--- a/src/config.y
+++ b/src/config.y
@@ -81,6 +81,9 @@
 %token TOK_FROM
 %token TOK_LOG
 %token TOK_LEVEL
+%token TOK_SYSLOG
+%token TOK_STDERR
+%token TOK_TO
 %token TOK_FATAL
 %token TOK_ERROR
 %token TOK_WARN
@@ -107,6 +110,8 @@
 }
 
 
+%type <num> maybe_log_level
+%type <num> log_level
 %type <num> port
 %type <boolean> boolean
 %type <num> maybe_port
@@ -139,15 +144,40 @@ statement:	TOK_LOG log ';'
 	|	TOK_INCLUDE include ';'
 	;
 
-log:		TOK_LEVEL log_level
+log:		TOK_LEVEL log_level {
+			conf->log_stderr_level = $2;
+		}
+	|	TOK_TO TOK_STDERR maybe_log_level {
+			conf->log_stderr_level = $3;
+		}
+	|	TOK_TO TOK_SYSLOG maybe_log_level {
+			conf->log_syslog_level = $3;
+		}
+	|	TOK_TO TOK_SYSLOG TOK_AS TOK_STRING maybe_log_level {
+			free(conf->log_syslog_ident);
+			conf->log_syslog_ident = strdup($4->str);
+
+			conf->log_syslog_level = $5;
+		}
+	|	TOK_TO TOK_STRING maybe_log_level {
+			if (!fastd_config_add_log_file(ctx, conf, $2->str, $3)) {
+				fastd_config_error(&@$, ctx, conf, filename, depth, "unable to set log file");
+				YYERROR;
+			}
+		}
 	;
 
-log_level:	TOK_FATAL	{ conf->loglevel = LOG_FATAL; }
-	|	TOK_ERROR	{ conf->loglevel = LOG_ERROR; }
-	|	TOK_WARN	{ conf->loglevel = LOG_WARN; }
-	|	TOK_INFO	{ conf->loglevel = LOG_INFO; }
-	|	TOK_VERBOSE	{ conf->loglevel = LOG_VERBOSE; }
-	|	TOK_DEBUG	{ conf->loglevel = LOG_DEBUG; }
+maybe_log_level:
+		TOK_LEVEL log_level	{ $$ = $2; }
+	|				{ $$ = FASTD_DEFAULT_LOG_LEVEL; }
+	;
+
+log_level:	TOK_FATAL	{ $$ = LOG_CRIT; }
+	|	TOK_ERROR	{ $$ = LOG_ERR; }
+	|	TOK_WARN	{ $$ = LOG_WARNING; }
+	|	TOK_INFO	{ $$ = LOG_NOTICE; }
+	|	TOK_VERBOSE	{ $$ = LOG_INFO; }
+	|	TOK_DEBUG	{ $$ = LOG_DEBUG; }
 	;
 
 interface:	TOK_STRING	{ free(conf->ifname); conf->ifname = strdup($1->str); }
@@ -197,7 +227,7 @@ method:		TOK_STRING {
 secret:		TOK_STRING	{ free(conf->secret); conf->secret = strdup($1->str); }
 	;
 
-on_up:		TOK_STRING	{
+on_up:		TOK_STRING {
 			free(conf->on_up);
 			free(conf->on_up_dir);
 
@@ -206,7 +236,7 @@ on_up:		TOK_STRING	{
 		}
 	;
 
-on_down:	TOK_STRING	{
+on_down:	TOK_STRING {
 			free(conf->on_down);
 			free(conf->on_down_dir);
 
@@ -215,7 +245,7 @@ on_down:	TOK_STRING	{
 		}
 	;
 
-on_establish:	TOK_STRING	{
+on_establish:	TOK_STRING {
 			free(conf->on_establish);
 			free(conf->on_establish_dir);
 
@@ -224,7 +254,7 @@ on_establish:	TOK_STRING	{
 		}
 	;
 
-on_disestablish: TOK_STRING	{
+on_disestablish: TOK_STRING {
 			free(conf->on_disestablish);
 			free(conf->on_disestablish_dir);
 
@@ -273,13 +303,15 @@ peer_remote:	TOK_ADDR port {
 		}
 	;
 
-peer_key:	TOK_STRING	{ free(conf->peers->key); conf->peers->key = strdup($1->str); }
+peer_key:	TOK_STRING {
+			free(conf->peers->key); conf->peers->key = strdup($1->str);
+		}
 	;
 
-peer_include:	TOK_STRING	{
-					if (!fastd_read_config(ctx, conf, $1->str, true, depth))
-						YYERROR;
-				}
+peer_include:	TOK_STRING {
+			if (!fastd_read_config(ctx, conf, $1->str, true, depth))
+				YYERROR;
+		}
 	;
 
 
@@ -308,7 +340,9 @@ maybe_port:	port		{ $$ = $1; }
 	|			{ $$ = 0; }
 	;
 
-maybe_as:	TOK_AS TOK_STRING { $$ = $2; }
+maybe_as:	TOK_AS TOK_STRING {
+			$$ = $2;
+		}
 	|			{ $$ = NULL; }
 	;
 
diff --git a/src/fastd.c b/src/fastd.c
index e270a26..a73c73d 100644
--- a/src/fastd.c
+++ b/src/fastd.c
@@ -85,6 +85,35 @@ static void init_pipes(fastd_context *ctx) {
 	ctx->resolvewfd = pipefd[1];
 }
 
+static void init_log(fastd_context *ctx) {
+	if (ctx->conf->log_syslog_level >= 0)
+		openlog(ctx->conf->log_syslog_ident, LOG_PID, LOG_DAEMON);
+
+	fastd_log_file *config;
+	for (config = ctx->conf->log_files; config; config = config->next) {
+		fastd_log_fd *file = malloc(sizeof(fastd_log_fd));
+
+		file->config = config;
+		file->fd = open(config->filename, O_WRONLY|O_APPEND|O_CREAT, 0600);
+
+		file->next = ctx->log_files;
+		ctx->log_files = file;
+	}
+}
+
+static void close_log(fastd_context *ctx) {
+	while (ctx->log_files) {
+		fastd_log_fd *next = ctx->log_files->next;
+
+		close(ctx->log_files->fd);
+		free(ctx->log_files);
+
+		ctx->log_files = next;
+	}
+
+	closelog();
+}
+
 static void init_sockets(fastd_context *ctx) {
 	struct sockaddr_in addr_in = ctx->conf->bind_addr_in;
 	struct sockaddr_in6 addr_in6 = ctx->conf->bind_addr_in6;
@@ -586,7 +615,7 @@ static void handle_input(fastd_context *ctx) {
 	update_time(ctx);
 
 	if (fds[0].revents & POLLIN)
-		handle_tun(ctx);
+	  handle_tun(ctx);
 	if (fds[1].revents & POLLIN)
 		handle_socket(ctx, ctx->sockfd);
 	if (fds[2].revents & POLLIN)
@@ -652,6 +681,8 @@ int main(int argc, char *argv[]) {
 	fastd_configure(&ctx, &conf, argc, argv);
 	ctx.conf = &conf;
 
+	init_log(&ctx);
+
 	if (conf.generate_key) {
 		conf.protocol->generate_key(&ctx);
 		exit(0);
@@ -672,7 +703,7 @@ int main(int argc, char *argv[]) {
 	init_peers(&ctx);
 
 	if (conf.daemon) {
-		if (daemon(0, 1) < 0)
+		if (daemon(1, 1) < 0)
 			exit_errno(&ctx, "daemon");
 	}
 
@@ -690,7 +721,12 @@ int main(int argc, char *argv[]) {
 
 		if (sighup) {
 			sighup = false;
+
+			close_log(&ctx);
+			init_log(&ctx);
+
 			fastd_reconfigure(&ctx, &conf);
+
 		}
 
 		pthread_sigmask(SIG_SETMASK, &oldset, NULL);
@@ -706,6 +742,7 @@ int main(int argc, char *argv[]) {
 	free(ctx.protocol_state);
 	free(ctx.eth_addr);
 
+	close_log(&ctx);
 	fastd_config_release(&ctx, &conf);
 
 	return 0;
diff --git a/src/fastd.h b/src/fastd.h
index 564b9c5..80f012b 100644
--- a/src/fastd.h
+++ b/src/fastd.h
@@ -33,12 +33,14 @@
 #include <errno.h>
 #include <linux/if_ether.h>
 #include <netinet/in.h>
+#include <stdarg.h>
 #include <stdbool.h>
 #include <stddef.h>
 #include <stdio.h>
 #include <stdint.h>
 #include <stdlib.h>
 #include <string.h>
+#include <syslog.h>
 #include <sys/uio.h>
 #include <sys/socket.h>
 #include <time.h>
@@ -107,8 +109,25 @@ struct _fastd_resolve_return {
 	fastd_peer_address addr;
 };
 
+struct _fastd_log_file {
+	fastd_log_file *next;
+
+	int level;
+	char *filename;
+};
+
+struct _fastd_log_fd {
+	fastd_log_fd *next;
+
+	fastd_log_file *config;
+	int fd;
+};
+
 struct _fastd_config {
-	fastd_loglevel loglevel;
+	int log_stderr_level;
+	int log_syslog_level;
+	char *log_syslog_ident;
+	fastd_log_file *log_files;
 
 	unsigned keepalive_interval;
 	unsigned peer_stale_time;
@@ -163,6 +182,8 @@ struct _fastd_config {
 struct _fastd_context {
 	const fastd_config *conf;
 
+	fastd_log_fd *log_files;
+
 	char *ifname;
 
 	struct timespec now;
@@ -198,13 +219,14 @@ void fastd_handle_receive(fastd_context *ctx, fastd_peer *peer, fastd_buffer buf
 
 void fastd_resolve_peer(fastd_context *ctx, const fastd_peer_config *peer);
 
-void fastd_printf(const fastd_context *ctx, const char *format, ...);
+int fastd_vsnprintf(const fastd_context *ctx, char *buffer, size_t size, const char *format, va_list ap);
 
 void fastd_read_peer_dir(fastd_context *ctx, fastd_config *conf, const char *dir);
 bool fastd_read_config(fastd_context *ctx, fastd_config *conf, const char *filename, bool peer_config, int depth);
 
 bool fastd_config_protocol(fastd_context *ctx, fastd_config *conf, const char *name);
 bool fastd_config_method(fastd_context *ctx, fastd_config *conf, const char *name);
+bool fastd_config_add_log_file(fastd_context *ctx, fastd_config *conf, const char *name, int level);
 void fastd_configure(fastd_context *ctx, fastd_config *conf, int argc, char *const argv[]);
 void fastd_reconfigure(fastd_context *ctx, fastd_config *conf);
 void fastd_config_release(fastd_context *ctx, fastd_config *conf);
@@ -216,36 +238,71 @@ static inline int fastd_rand(fastd_context *ctx, int min, int max) {
 	return (r%(max-min) + min);
 }
 
-#define pr_log(ctx, level, prefix, args...) do { \
-		if ((ctx)->conf == NULL || (level) <= (ctx)->conf->loglevel) { \
-			char timestr[100]; \
-			time_t t; \
-			struct tm tm; \
-			\
-			t = time(NULL); \
-			if (localtime_r(&t, &tm) != NULL) { \
-				if (strftime(timestr, sizeof(timestr), "%F %T %z --- ", &tm) > 0) \
-					fputs(timestr, stderr); \
-			} \
-			\
-			fputs(prefix, stderr); \
-			fastd_printf(ctx, args); \
-			fputs("\n", stderr); \
-		} \
-	} while(0)
-
-#define is_error(ctx) ((ctx)->conf == NULL || LOG_ERROR <= (ctx)->conf->loglevel)
-#define is_warn(ctx) ((ctx)->conf == NULL || LOG_WARN <= (ctx)->conf->loglevel)
-#define is_info(ctx) ((ctx)->conf == NULL || LOG_INFO <= (ctx)->conf->loglevel)
-#define is_verbose(ctx) ((ctx)->conf == NULL || LOG_VERBOSE <= (ctx)->conf->loglevel)
-#define is_debug(ctx) ((ctx)->conf == NULL || LOG_DEBUG <= (ctx)->conf->loglevel)
-
-#define pr_fatal(ctx, args...) pr_log(ctx, LOG_FATAL, "Fatal: ", args)
-#define pr_error(ctx, args...) pr_log(ctx, LOG_ERROR, "Error: ", args)
-#define pr_warn(ctx, args...) pr_log(ctx, LOG_WARN, "Warning: ", args)
-#define pr_info(ctx, args...) pr_log(ctx, LOG_INFO, "Info: ", args)
-#define pr_verbose(ctx, args...) pr_log(ctx, LOG_VERBOSE, "Verbose: ", args)
-#define pr_debug(ctx, args...) pr_log(ctx, LOG_DEBUG, "DEBUG: ", args)
+
+#define FASTD_DEFAULT_LOG_LEVEL	LOG_INFO
+
+
+static inline const char* get_log_prefix(int log_level) {
+	switch(log_level) {
+	case LOG_CRIT:
+		return "Fatal: ";
+	case LOG_ERR:
+		return "Error: ";
+	case LOG_WARNING:
+		return "Warning: ";
+	case LOG_NOTICE:
+		return "Info: ";
+	case LOG_INFO:
+		return "Verbose: ";
+	case LOG_DEBUG:
+		return "DEBUG: ";
+	default:
+		return "";
+	}
+}
+
+static inline void pr_log(const fastd_context *ctx, int level, const char *format, ...) {
+	char buffer[1024];
+	char timestr[100] = "";
+	va_list ap;
+
+	va_start(ap, format);
+	fastd_vsnprintf(ctx, buffer, sizeof(buffer), format, ap);
+	va_end(ap);
+
+	buffer[sizeof(buffer)-1] = 0;
+
+	if (ctx->conf == NULL || level <= ctx->conf->log_stderr_level || ctx->conf->log_files) {
+		time_t t;
+		struct tm tm;
+
+		t = time(NULL);
+		if (localtime_r(&t, &tm) != NULL) {
+			if (strftime(timestr, sizeof(timestr), "%F %T %z --- ", &tm) <= 0)
+				*timestr = 0;
+		}
+	}
+
+	if (ctx->conf == NULL || level <= ctx->conf->log_stderr_level)
+		fprintf(stderr, "%s%s%s\n", timestr, get_log_prefix(level), buffer);
+
+	if (level <= ctx->conf->log_syslog_level)
+		syslog(level, "%s", buffer);
+
+	fastd_log_fd *file;
+	for (file = ctx->log_files; file; file = file->next) {
+		if (level <= file->config->level)
+			dprintf(file->fd, "%s%s%s\n", timestr, get_log_prefix(level), buffer);
+	}
+}
+
+
+#define pr_fatal(ctx, args...) pr_log(ctx, LOG_CRIT, args)
+#define pr_error(ctx, args...) pr_log(ctx, LOG_ERR, args)
+#define pr_warn(ctx, args...) pr_log(ctx, LOG_WARNING, args)
+#define pr_info(ctx, args...) pr_log(ctx, LOG_NOTICE, args)
+#define pr_verbose(ctx, args...) pr_log(ctx, LOG_INFO, args)
+#define pr_debug(ctx, args...) pr_log(ctx, LOG_DEBUG, args)
 
 #define pr_warn_errno(ctx, message) pr_warn(ctx, "%s: %s", message, strerror(errno))
 #define pr_error_errno(ctx, message) pr_warn(ctx, "%s: %s", message, strerror(errno))
diff --git a/src/printf.c b/src/printf.c
index cbecbc8..bf2bc35 100644
--- a/src/printf.c
+++ b/src/printf.c
@@ -28,207 +28,122 @@
 #include "peer.h"
 
 #include <arpa/inet.h>
-#include <stdarg.h>
 
 
-static void print_peer_address(const fastd_context *ctx, const fastd_peer_address *address) {
+static inline int snprintf_safe(char *buffer, size_t size, const char *format, ...) {
+	va_list ap;
+	va_start(ap, format);
+	int ret = vsnprintf(buffer, size, format, ap);
+	va_end(ap);
+
+	return ret < 0 ? 0 : ret > size ? size : ret;
+}
+
+static int snprint_peer_address(const fastd_context *ctx, char *buffer, size_t size, const fastd_peer_address *address) {
 	char addr_buf[INET6_ADDRSTRLEN] = "";
 
 	switch (address->sa.sa_family) {
 	case AF_UNSPEC:
-		fputs("floating", stderr);
-		return;
+		return snprintf(buffer, size, "floating");
 
 	case AF_INET:
 		if (inet_ntop(AF_INET, &address->in.sin_addr, addr_buf, sizeof(addr_buf)))
-			fprintf(stderr, "%s:%u", addr_buf, ntohs(address->in.sin_port));
-		return;
+			return snprintf_safe(buffer, size, "%s:%u", addr_buf, ntohs(address->in.sin_port));
+		else
+			return 0;
 
 	case AF_INET6:
 		if (inet_ntop(AF_INET6, &address->in6.sin6_addr, addr_buf, sizeof(addr_buf)))
-			fprintf(stderr, "[%s]:%u", addr_buf, ntohs(address->in6.sin6_port));
-		break;
+			return snprintf_safe(buffer, size, "[%s]:%u", addr_buf, ntohs(address->in6.sin6_port));
+		else
+			return 0;
 
 	default:
 		exit_bug(ctx, "unsupported address family");
 	}
 }
 
-static void print_peer_str(const fastd_context *ctx, const fastd_peer *peer) {
-	if (peer->config && peer->config->name) {
-		fprintf(stderr, "<%s>", peer->config->name);
-	}
-	else {
-		fputs("<(null)>", stderr);
-	}
+static int snprint_peer_str(const fastd_context *ctx, char *buffer, size_t size, const fastd_peer *peer) {
+	if (peer->config && peer->config->name)
+		return snprintf_safe(buffer, size, "<%s>", peer->config->name);
+	else
+		return snprintf_safe(buffer, size, "<(null)>");
 }
 
-#pragma GCC diagnostic ignored "-Wformat-security"
+int fastd_vsnprintf(const fastd_context *ctx, char *buffer, size_t size, const char *format, va_list ap) {
+	char *buffer_start = buffer;
+	char *buffer_end = buffer+size;
 
-void fastd_printf(const fastd_context *ctx, const char *format, ...) {
-	va_list ap;
-	va_start(ap, format);
+	*buffer = 0;
 
-	char *format_dup = strdup(format);
-	char *str;
-	for (str = format_dup; *str; str++) {
-		if (*str != '%') {
-			fputc(*str, stderr);
+	for (; *format; format++) {
+		const void *p;
+		const fastd_eth_addr *eth_addr;
+
+		if (buffer >= buffer_end)
+			break;
+
+		if (*format != '%') {
+			*buffer = *format;
+			buffer++;
 			continue;
 		}
 
-		int len, flag_l = 0, flag_L = 0, flag_j = 0, flag_z = 0, flag_t = 0;
-
-		for(len = 1; str[len]; len++) {
-			char last;
-			bool finished = true;
-			const void *p;
-			const fastd_eth_addr *eth_addr;
-
-			switch (str[len]) {
-			case 'l':
-				flag_l++;
-				finished = false;
-				break;
-
-			case 'L':
-				flag_L++;
-				finished = false;
-				break;
-
-			case 'j':
-				flag_j++;
-				finished = false;
-				break;
-
-			case 'z':
-				flag_z++;
-				finished = false;
-				break;
-
-			case 't':
-				flag_t++;
-				finished = false;
-				break;
-
-			case '%':
-				fputc('%', stderr);
-				break;
-
-			case 'd':
-			case 'i':
-			case 'o':
-			case 'u':
-			case 'x':
-			case 'X':
-				last = str[len+1];
-				str[len+1] = 0;
-
-				if (flag_j)
-					fprintf(stderr, str, va_arg(ap, intmax_t));
-				else if (flag_z)
-					fprintf(stderr, str, va_arg(ap, size_t));
-				else if (flag_t)
-					fprintf(stderr, str, va_arg(ap, ptrdiff_t));
-				else if (flag_l == 0)
-					fprintf(stderr, str, va_arg(ap, int));
-				else if (flag_l == 1)
-					fprintf(stderr, str, va_arg(ap, long));
-				else
-					fprintf(stderr, str, va_arg(ap, long long));
-
-				str[len+1] = last;
-				break;
-
-			case 'e':
-			case 'f':
-			case 'F':
-			case 'g':
-			case 'G':
-			case 'a':
-			case 'A':
-				last = str[len+1];
-				str[len+1] = 0;
-
-				if (flag_L)
-					fprintf(stderr, str, va_arg(ap, long double));
-				else
-					fprintf(stderr, str, va_arg(ap, double));
-
-				str[len+1] = last;
-				break;
-
-			case 'c':
-				last = str[len+1];
-				str[len+1] = 0;
-
-				fprintf(stderr, str, va_arg(ap, int));
-
-				str[len+1] = last;
-				break;
-
-			case 's':
-			case 'p':
-				last = str[len+1];
-				str[len+1] = 0;
-
-				fprintf(stderr, str, va_arg(ap, void*));
-
-				str[len+1] = last;
-				break;
-
-			case 'm':
-				last = str[len+1];
-				str[len+1] = 0;
-
-				fprintf(stderr, str);
-
-				str[len+1] = last;
-				break;
-
-			case 'E':
-				eth_addr = va_arg(ap, const fastd_eth_addr*);
-
-				if (eth_addr) {
-					fprintf(stderr, "%02x:%02x:%02x:%02x:%02x:%02x",
-						eth_addr->data[0], eth_addr->data[1], eth_addr->data[2],
-						eth_addr->data[3], eth_addr->data[4], eth_addr->data[5]);
-				}
-				else {
-					fputs("(null)", stderr);
-				}
-				break;
-
-			case 'P':
-				p = va_arg(ap, const fastd_peer*);
-
-				if (p)
-					print_peer_str(ctx, (const fastd_peer*)p);
-				else
-					fputs("(null)", stderr);
-				break;
-
-			case 'I':
-				p = va_arg(ap, const fastd_peer_address*);
-
-				if (p)
-					print_peer_address(ctx, (const fastd_peer_address*)p);
-				else
-					fputs("(null)", stderr);
-				break;
-
-			default:
-				finished = false;
-			}
+		format++;
+
+		switch(*format) {
+		case 'i':
+			buffer += snprintf_safe(buffer, buffer_end-buffer, "%i", va_arg(ap, int));
+			break;
+
+		case 'u':
+			buffer += snprintf_safe(buffer, buffer_end-buffer, "%u", va_arg(ap, unsigned int));
+			break;
 
-			if (finished) {
-				str += len;
-				break;
+		case 's':
+			buffer += snprintf_safe(buffer, buffer_end-buffer, "%s", va_arg(ap, char*));
+			break;
+
+		case 'E':
+			eth_addr = va_arg(ap, const fastd_eth_addr*);
+
+			if (eth_addr) {
+				buffer += snprintf_safe(buffer, buffer_end-buffer, "%02x:%02x:%02x:%02x:%02x:%02x",
+							eth_addr->data[0], eth_addr->data[1], eth_addr->data[2],
+							eth_addr->data[3], eth_addr->data[4], eth_addr->data[5]);
 			}
+			else {
+				buffer += snprintf_safe(buffer, buffer_end-buffer, "(null)");
+			}
+			break;
+
+		case 'P':
+			p = va_arg(ap, const fastd_peer*);
+
+			if (p)
+				buffer += snprint_peer_str(ctx, buffer, buffer_end-buffer, (const fastd_peer*)p);
+			else
+				buffer += snprintf_safe(buffer, buffer_end-buffer, "(null)");
+			break;
+
+		case 'I':
+			p = va_arg(ap, const fastd_peer_address*);
+
+			if (p)
+				buffer += snprint_peer_address(ctx, buffer, buffer_end-buffer, (const fastd_peer_address*)p);
+			else
+				buffer += snprintf_safe(buffer, buffer_end-buffer, "(null)");
+			break;
+
+		default:
+			pr_warn(ctx, "fastd_vsnprintf: unknown format conversion specifier '%c'", *format);
+			*buffer_start = 0;
+			return -1;
 		}
 	}
 
-	free(format_dup);
+	if (buffer < buffer_end)
+		*buffer = 0;
 
-	va_end(ap);
+	return buffer-buffer_start;
 }
diff --git a/src/types.h b/src/types.h
index 6efd224..c213118 100644
--- a/src/types.h
+++ b/src/types.h
@@ -33,15 +33,6 @@
 #ifndef _FASTD_TYPES_H_
 #define _FASTD_TYPES_H_
 
-typedef enum _fastd_loglevel {
-	LOG_FATAL = 0,
-	LOG_ERROR,
-	LOG_WARN,
-	LOG_INFO,
-	LOG_VERBOSE,
-	LOG_DEBUG,
-} fastd_loglevel;
-
 typedef enum _fastd_mode {
 	MODE_TAP,
 	MODE_TUN,
@@ -56,6 +47,9 @@ typedef struct _fastd_eth_addr fastd_eth_addr;
 typedef struct _fastd_peer fastd_peer;
 typedef struct _fastd_peer_eth_addr fastd_peer_eth_addr;
 
+typedef struct _fastd_log_file fastd_log_file;
+typedef struct _fastd_log_fd fastd_log_fd;
+
 typedef struct _fastd_config fastd_config;
 typedef struct _fastd_context fastd_context;