logger: initial support for logging to a remote host

This is the first RFC5424 (only) support for for logging to a remote
host.  The syntax continues to follow the FreeBSD logger.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

src/logger.c

@@ -35,11 +35,14 @@
 #include <err.h>
 #include <errno.h>
 #include <getopt.h>
+#include <netdb.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
 #include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/socket.h>
 
 #define SYSLOG_NAMES
 #include "compat.h"
@@ -122,6 +125,77 @@ static void log_kmsg(FILE *fp, char *ident, int pri, int opts, char *buf)
 	fprintf(fp, "<%d>%s[%d]:%s\n", pri, ident, getpid(), buf);
 }
 
+/*
+ * Used on systems that don't have sa->sa_len
+ */
+#ifndef HAVE_SA_LEN
+static socklen_t sa_len(struct sockaddr *sa)
+{
+	if (sa->sa_family == AF_INET6)
+		return sizeof(struct sockaddr_in6);
+	if (sa->sa_family == AF_INET)
+		return sizeof(struct sockaddr_in);
+	return 0;
+}
+#endif
+#include <arpa/inet.h>
+static void print_addr(struct sockaddr *sa)
+{
+	struct sockaddr_in6 *sin6;
+	struct sockaddr_in *sin;
+	socklen_t len;
+	void *address;
+	char buf[128];
+
+	if (sa->sa_family == AF_INET6) {
+		sin6 = (struct sockaddr_in6 *)sa;
+		address = &sin6->sin6_addr;
+		len = sizeof(*sin6);
+	} else {
+		sin = (struct sockaddr_in *)sa;
+		address = &sin->sin_addr;
+		len = sizeof(*sin);
+	}
+
+	printf("address %s len %u vs calculated %u\n",
+	       inet_ntop(sa->sa_family, address, buf, sizeof(buf)),
+			 len, sa_len(sa));
+}
+
+static int nslookup(const char *host, const char *svcname, int family, struct sockaddr *sa)
+{
+	struct addrinfo hints, *ai, *result;
+	int error;
+
+	memset(&hints, 0, sizeof(hints));
+	hints.ai_flags    = !host ? AI_PASSIVE : 0;
+	hints.ai_family   = family;
+	hints.ai_socktype = SOCK_DGRAM;
+
+	error = getaddrinfo(host, svcname, &hints, &result);
+	if (error == EAI_SERVICE) {
+		warnx("%s/udp: unknown service, trying syslog port 514", svcname);
+		svcname = "514";
+		error = getaddrinfo(host, svcname, &hints, &result);
+	}
+	if (error) {
+		warnx("%s (%s:%s)", gai_strerror(error), host, svcname);
+		return 1;
+	}
+
+	for (ai = result; ai; ai = ai->ai_next) {
+		print_addr(ai->ai_addr);
+		if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
+			continue;
+
+		memcpy(sa, ai->ai_addr, ai->ai_addrlen);
+		break;
+	}
+	freeaddrinfo(result);
+
+	return 0;
+}
+
 static int checksz(FILE *fp, off_t sz)
 {
 	struct stat st;
@@ -220,21 +294,32 @@ static int usage(int code)
 
 int main(int argc, char *argv[])
 {
-	FILE *fp = NULL;
-	int c, num = 5;
 	int facility = LOG_USER;
 	int severity = LOG_INFO;
+	int family = AF_UNSPEC;
+	FILE *fp = NULL;
+	int c, num = 5;
 	int log_opts = 0;
 	int rotate = 0;
 	int allow_kmsg = 0;
 	off_t size = 200 * 1024;
 	char *ident = NULL, *logfile = NULL;
 	char *msgid = NULL, *sd = NULL;
-	char *sockpath = NULL;
+	char *host = NULL, *sockpath = NULL;
+	char *svcname = "syslog";
+	struct sockaddr sa;
 	char buf[512] = "";
 
-	while ((c = getopt(argc, argv, "?cd:f:ikm:np:r:st:u:v")) != EOF) {
+	while ((c = getopt(argc, argv, "46?cd:f:h:ikm:np:P:r:st:u:v")) != EOF) {
 		switch (c) {
+		case '4':
+			family = AF_INET;
+			break;
+
+		case '6':
+			family = AF_INET6;
+			break;
+
 		case 'c':
 			log_opts |= LOG_CONS;
 			break;
@@ -247,6 +332,10 @@ int main(int argc, char *argv[])
 			logfile = optarg;
 			break;
 
+		case 'h':
+			host = optarg;
+			break;
+
 		case 'i':
 			log_opts |= LOG_PID;
 			break;
@@ -272,6 +361,10 @@ int main(int argc, char *argv[])
 				return usage(1);
 			break;
 
+		case 'P':
+			svcname = optarg;
+			break;
+
 		case 'r':
 			parse_rotation(optarg, &size, &num);
 			if (size > 0 && num > 0)
@@ -351,6 +444,11 @@ int main(int argc, char *argv[])
 
 			return fclose(fp);
 		}
+	} else if (host) {
+		log.log_host = &sa;
+		if (nslookup(host, svcname, family, &sa))
+			return 1;
+		log_opts |= LOG_NDELAY;
 	}
 
 	openlog_r(ident, log_opts, facility, &log);

src/syslog.c

@@ -96,6 +96,20 @@ is_socket(int fd)
 	return 1;
 }
 
+/*
+ * Used on systems that don't have sa->sa_len
+ */
+#ifndef HAVE_SA_LEN
+static socklen_t sa_len(struct sockaddr *sa)
+{
+	if (sa->sa_family == AF_INET6)
+		return sizeof(struct sockaddr_in6);
+	if (sa->sa_family == AF_INET)
+		return sizeof(struct sockaddr_in);
+	return 0;
+}
+#endif
+
 /*
  * syslog, vsyslog --
  *	print message on log file; output is intended for syslogd(8).
@@ -190,6 +204,8 @@ vsyslogp_r(int pri, struct syslog_data *data, const char *msgid,
 {
 	static const char BRCOSP[] = "]: ";
 	static const char CRLF[] = "\r\n";
+	struct sockaddr *sa = NULL;
+	socklen_t len = 0;
 	size_t cnt, prlen, tries;
 	char ch, *p, *t;
 	struct timeval tv;
@@ -425,8 +441,17 @@ vsyslogp_r(int pri, struct syslog_data *data, const char *msgid,
 		goto done;
 	}
 
+	if (data->log_host) {
+		sa  = data->log_host;
+#ifdef HAVE_SA_LEN
+		len = sa->sa_len;
+#else
+		len = sa_len(sa);
+#endif
+	}
+
 	/*
-	 * If the send() failed, there are two likely scenarios:
+	 * If the send() fails, there are two likely scenarios:
 	 *  1) syslogd was restarted
 	 *  2) /dev/log is out of socket buffer space
 	 * We attempt to reconnect to /dev/log to take care of
@@ -434,7 +459,7 @@ vsyslogp_r(int pri, struct syslog_data *data, const char *msgid,
 	 * to give syslogd a chance to empty its socket buffer.
 	 */
 	for (tries = 0; tries < MAXTRIES; tries++) {
-		if (send(data->log_file, tbuf, cnt, 0) != -1)
+		if (sendto(data->log_file, tbuf, cnt, 0, sa, len) != -1)
 			break;
 		if (errno != ENOBUFS) {
 			disconnectlog_r(data);
@@ -487,7 +512,7 @@ disconnectlog_r(struct syslog_data *data)
 static void
 connectlog_r(struct syslog_data *data)
 {
-	/* AF_UNIX address of local logger */
+	struct sockaddr *sa = data->log_host;
 	static struct sockaddr_un sun = {
 		.sun_family = AF_LOCAL,
 #ifdef HAVE_SA_LEN
@@ -495,28 +520,48 @@ connectlog_r(struct syslog_data *data)
 #endif
 		.sun_path = _PATH_LOG,
 	};
+	socklen_t len;
+	int family;
 	char *path;
 
-	path = getenv("SYSLOG_UNIX_PATH");
+	if (sa) {
-	if (!data->log_sockpath && path)
+		family = sa->sa_family;
-		data->log_sockpath = path;
+#ifdef HAVE_SA_LEN
-	if (data->log_sockpath && !access(data->log_sockpath, W_OK))
+		len = sa->sa_len;
-		strlcpy(sun.sun_path, data->log_sockpath, sizeof(sun.sun_path));
+#else
+		len = sa_len(sa);
+#endif
+	} else {
+		sa  = (struct sockaddr *)&sun;
+		family = AF_UNIX;
+#ifdef HAVE_SA_LEN
+		len = sa->sa_len;
+#else
+		len = sizeof(sun);
+#endif
+
+		path = getenv("SYSLOG_UNIX_PATH");
+		if (!data->log_sockpath && path)
+			data->log_sockpath = path;
+
+		if (data->log_sockpath && !access(data->log_sockpath, W_OK))
+			strlcpy(sun.sun_path, data->log_sockpath, sizeof(sun.sun_path));
+	}
 
 	if (data->log_file == -1 || fcntl(data->log_file, F_GETFL, 0) == -1) {
-		data->log_file = socket(AF_UNIX, SOCK_DGRAM | SOCK_CLOEXEC, 0);
+		data->log_file = socket(family, SOCK_DGRAM | SOCK_CLOEXEC, 0);
 		if (data->log_file == -1)
 			return;
 		data->log_connected = 0;
 	}
+
 	if (!data->log_connected) {
 		if (!is_socket(data->log_file)) {
 			data->log_connected = 1;
 			return;
 		}
 
-		if (connect(data->log_file, (const struct sockaddr *)&sun,
+		if (connect(data->log_file, sa, len) == -1) {
-			    sizeof(sun)) == -1) {
 			(void)close(data->log_file);
 			data->log_file = -1;
 		} else

src/syslog.h

@@ -206,6 +206,7 @@ struct syslog_data {
 	char	log_hostname[256];	/* MAXHOSTNAMELEN */
 	int	log_fac;
 	int	log_mask;
+	void	*log_host;		/* struct sockaddr* */
 };
 
 #define SYSLOG_DATA_INIT { \
@@ -219,6 +220,7 @@ struct syslog_data {
     .log_hostname = { '\0' }, \
     .log_fac = LOG_USER, \
     .log_mask = 0xff, \
+    .log_host = NULL, \
 }
 
 #ifdef __cplusplus