Cross-platform syslog logging stuff.

Allows UDP syslog logging on any system...
On Win32, will default to logging to localhost whereas on *nix, the
openlog(), syslog(), and vsyslog() functions are wrappers if no log host
is set with xp_set_loghost()

Untested, unused, not part of xpdev builds currently.

src/xpdev/xp_syslog.c

+#include <stdarg.h>
+#ifdef __unix__
+#include <syslog.h>
+#endif
+
+#include "xp_syslog.h"
+#include "sockwrap.h"
+#include "gen_defs.h"
+
+static SOCKET syslog_sock=INVALID_SOCKET;
+static char log_host[1025]=
+#ifdef __unix__
+"";
+#else
+"localhost";
+#endif
+
+static char syslog_tag[33]="undefined";
+static int default_facility=LOG_USER;
+
+static u_long resolve_ip(char *addr)
+{
+	HOSTENT*        host;
+	char*           p;
+
+	if(*addr==0)
+		return((u_long)INADDR_NONE);
+
+	for(p=addr;*p;p++)
+		if(*p!='.' && !isdigit(*p))
+			break;
+	if(!(*p))
+		return(inet_addr(addr));
+	if((host=gethostbyname(addr))==NULL)
+		return((u_long)INADDR_NONE);
+	return(*((ulong*)host->h_addr_list[0]));
+}
+
+void xp_set_loghost(const char *hostname)
+{
+	SAFECOPY(log_host, hostname);
+}
+
+void xp_openlog(const char *ident, int logopt, int facility)
+{
+	int		sock;
+	SOCKADDR_IN	syslog_addr;
+	socklen_t	syslog_len;
+
+#ifdef __unix__
+	if(!log_host[0]) {
+		openlog(ident,logopt,facility);
+		return;
+	}
+#endif
+
+	memset(&syslog_addr, 0, sizeof(syslog_addr));
+	syslog_addr.sin_addr.s_addr=INADDR_ANY;
+	syslog_addr.sin_family=AF_INET;
+	syslog_addr.sin_port=htons(SYSLOG_PORT);
+
+	syslog_sock=socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);
+	if(syslog_sock==INVALID_SOCKET)
+		return;
+	/*
+	 * If the bind() fails, that's OK... we're just trying to set the source port to
+	 * 514 here as reccomended by the RFC.  This isn't REQUIRED though.
+	 */
+	bind(syslog_sock, (struct sockaddr *)&syslog_addr, sizeof(syslog_addr));
+	syslog_addr.sin_addr.s_addr=resolve_ip(log_host);
+	if(connect(syslog_sock, (struct sockaddr *)&syslog_addr, sizeof(syslog_addr))) {
+		closesocket(syslog_sock);
+		syslog_sock=INVALID_SOCKET;
+		return;
+	}
+
+	SAFECOPY(syslog_tag, ident);
+}
+
+void xp_vsyslog(int priority, const char *message, va_list va)
+{
+	int orig_errno=ERROR_VALUE;
+	time_t	now;
+	char	timestr[32];
+	char	msg_to_send[1025];
+	char	format[1025];
+	char	*msg_end;
+	char	*p;
+	int		i;
+
+#ifdef __unix__
+	if(!log_host[0]) {
+		vsyslog(priority, message, va);
+		return;
+	}
+#endif
+
+	/* Ensure we can even send this thing */
+	if(syslog_sock==INVALID_SOCKET)
+		return;
+
+	/* Check for valid priority */
+	if(priority & ~(LOG_PRIMASK|LOG_FACMASK)) {
+		i=priority;
+		/* Fix to something legal */
+		priority &= (LOG_PRIMASK|LOG_FACMASK);
+		/* Ooooo... re-entrant! */
+		syslog(priority,"Unknown priority %x",i);
+	}
+
+	/* Set default facility if needed */
+	if(!(priority & LOG_FACMASK))
+		priority |= default_facility;
+
+	time(&now);
+	ctime_r(&now, timestr);
+	/* Remove trailing \n */
+	timestr[24]=0;
+
+	snprintf(format, sizeof(format), "<%d>%.15s %.32s: %s", priority, timestr+4 /* Remove day of week */, syslog_tag, message);
+	format[sizeof(format)-1]=0;
+	vsnprintf(msg_to_send, sizeof(msg_to_send), format, va);
+	msg_to_send[sizeof(msg_to_send)-1]=0;
+
+	/* Clean out invalid chars (as per RFC3164) */
+	msg_end=msg_to_send+sizeof(msg_to_send)-1;
+	for(p=msg_to_send; *p; p++) {
+		if(*p<32) {
+			i=strlen(p);
+			memmove(p, p+1, i);
+			*p='^';
+			p++;
+			*p|=0x40;
+			if(p+i > msg_end)
+				*msg_end=0;
+			else
+				*(p+i)=0;
+		}
+		else if(*p>126)
+			*p=' ';
+	}
+	sendsocket(syslog_sock, msg_to_send, strlen(msg_to_send));
+}
+
+void xp_syslog(int priority, const char *message, ...)
+{
+	va_list va;
+
+	va_start(va, message);
+	vsyslog(priority, message, va);
+	va_end(va);
+}

src/xpdev/xp_syslog.h

+#ifndef XP_SYSLOG_H_
+#define XP_SYSLOG_H_
+#include <stdarg.h>
+
+
+/* priorities */
+#define LOG_EMERG		0		/* system is unusable */
+#define LOG_ALERT		1		/* action must be taken immediately */
+#define LOG_CRIT		2		/* critical conditions */
+#define LOG_ERR			3		/* error conditions */
+#define LOG_WARNING		4		/* warning conditions */
+#define LOG_NOTICE		5		/* normal but significant condition */
+#define LOG_INFO		6		/* informational */
+#define LOG_DEBUG		7		/* debug-level messages */
+
+#define LOG_KERN		(0<<3)	/* kernel messages */
+#define LOG_USER		(1<<3)	/* random user-level messages */
+#define LOG_MAIL		(2<<3)	/* mail system */
+#define LOG_DAEMON		(3<<3)	/* system daemons */
+#define LOG_AUTH		(4<<3)	/* authorization messages */
+#define LOG_SYSLOG		(5<<3)	/* messages generated internally by syslogd */
+#define LOG_LPR			(6<<3)	/* line printer subsystem */
+#define LOG_NEWS		(7<<3)	/* network news subsystem */
+#define LOG_UUCP		(8<<3)	/* UUCP subsystem */
+#define LOG_CRON		(9<<3)	/* clock daemon */
+#define LOG_AUTHPRIV	(10<<3)	/* authorization messages (private) */
+								/* Facility #10 clashes in DEC UNIX, where */
+								/* it's defined as LOG_MEGASAFE for AdvFS  */
+								/* event logging.                          */
+#define LOG_FTP			(11<<3)	/* ftp daemon */
+#define LOG_NTP			(12<<3)	/* NTP subsystem */
+#define LOG_SECURITY	(13<<3)	/* security subsystems (firewalling, etc.) */
+#define LOG_CONSOLE		(14<<3)	/* /dev/console output */
+
+/* facility codes */
+#define LOG_LOCAL0		(16<<3)	/* reserved for local use */
+#define LOG_LOCAL1		(17<<3)	/* reserved for local use */
+#define LOG_LOCAL2		(18<<3)	/* reserved for local use */
+#define LOG_LOCAL3		(19<<3)	/* reserved for local use */
+#define LOG_LOCAL4		(20<<3)	/* reserved for local use */
+#define LOG_LOCAL5		(21<<3)	/* reserved for local use */
+#define LOG_LOCAL6		(22<<3)	/* reserved for local use */
+#define LOG_LOCAL7		(23<<3)	/* reserved for local use */
+
+/* Masks to extract parts */
+#define LOG_PRIMASK     0x07    /* mask to extract priority part */
+#define LOG_FACMASK     0x03f8  /* mask to extract facility part */
+
+/* Port number */
+#define SYSLOG_PORT 514
+
+void xp_set_loghost(const char *hostname);
+void xp_openlog(const char *ident, int logopt, int facility);
+void xp_vsyslog(int priority, const char *message, va_list va);
+void xp_syslog(int priority, const char *message, ...);
+
+#endif