[PATCH v2 7/7] misc: syslog: Use RFC5424
Adhemerval Zanella
adhemerval.zanella@linaro.org
Fri Feb 18 14:23:22 GMT 2022
Current syslog format provides limited timestamp information (not full
year information nor microsecond precision) and the timezone information
might incur in confusion [1] since there is no metadata information on
how it was generated.
So instead of using another ad-hoc syslog format, this patch adapts it
to follow RFC5424:
- VERSION is set as 1.
- TIMESTAMP is logged as described by RFC 3339 using UTC ('Z') with
maximum allowed TIME-SECFRAC precision (microseconds).
- HOSTNAME is obtained with gethostname (as allowed by the RFC).
- PROCID is only set if LOG_PID is previously set by openlog.
- MSGID and STRUCTURED-DATA are both set to NILVALUE.
Checked on x86_64-linux-gnu.
[1] https://sourceware.org/pipermail/libc-alpha/2021-March/123583.html
---
misc/syslog.c | 79 +++++++++++++++++++++++++++++++++--------------
misc/tst-syslog.c | 28 ++++++++---------
2 files changed, 69 insertions(+), 38 deletions(-)
diff --git a/misc/syslog.c b/misc/syslog.c
index 088e3b5664..f15a536dd7 100644
--- a/misc/syslog.c
+++ b/misc/syslog.c
@@ -31,6 +31,7 @@
static char sccsid[] = "@(#)syslog.c 8.4 (Berkeley) 3/18/94";
#endif /* LIBC_SCCS and not lint */
+#include <intprops.h>
#include <libc-lock.h>
#include <libio/libioP.h>
#include <math_ldbl_opt.h>
@@ -42,6 +43,10 @@ static char sccsid[] = "@(#)syslog.c 8.4 (Berkeley) 3/18/94";
#include <sys/un.h>
#include <stdio_ext.h>
+#ifndef HOST_NAME_MAX
+# define HOST_NAME_MAX 64
+#endif
+
static int LogType = SOCK_DGRAM; /* type of socket connection */
static int LogFile = -1; /* fd for log */
static bool connected; /* have done connect */
@@ -117,6 +122,39 @@ __vsyslog_chk(int pri, int flag, const char *fmt, va_list ap)
__vsyslog_internal (pri, fmt, ap, (flag > 0) ? PRINTF_FORTIFY : 0);
}
+/* Defined by RFC5424. */
+#define NILVALUE "-"
+
+struct timebuf
+{
+ /* Leave room for outlandish but possible years.
+ The "+ 1" is for strftime's adding 1900 to tm_year. */
+ char b[INT_STRLEN_BOUND (int) + 1
+ + sizeof "-MM-DDThh:mm:ss.nnnnnnZ"];
+};
+
+
+/* Fill TIMEBUF with a RFC3339 timestamp. Use UTC time and maximum
+ TIME-SECFRAC accurancy allowed (6 digits for microseconds). */
+static void
+syslog_rfc3339_timestamp (struct timebuf *timebuf)
+{
+ struct __timespec64 ts;
+ __clock_gettime64 (TIME_CLOCK_GETTIME_CLOCKID, &ts);
+ struct tm now_tm;
+ struct tm *gmtm = __gmtime64_r (&ts.tv_sec, &now_tm);
+ if (gmtm == NULL)
+ strcpy (timebuf->b, NILVALUE);
+ else
+ {
+ size_t datebytes = __strftime_l (timebuf->b, sizeof timebuf->b,
+ "%FT%T", gmtm, _nl_C_locobj_ptr);
+ int usec = ts.tv_nsec / 1000;
+ __snprintf (timebuf->b + datebytes, sizeof timebuf->b - datebytes,
+ ".%06dZ", usec);
+ }
+}
+
void
__vsyslog_internal(int pri, const char *fmt, va_list ap,
unsigned int mode_flags)
@@ -149,35 +187,30 @@ __vsyslog_internal(int pri, const char *fmt, va_list ap,
if ((pri & LOG_FACMASK) == 0)
pri |= LogFacility;
- pid_t pid = LogStat & LOG_PID ? __getpid () : 0;
+ struct timebuf timestamp;
+ syslog_rfc3339_timestamp (×tamp);
- enum
- {
- timebuf_size = 3+1 /* "%h " */
- + 2+1 /* "%e " */
- + 2+1 + 2+1 + 2+1 + 1, /* "%T " */
-
- bufs_size = 1024
- };
+ char hostname[HOST_NAME_MAX];
+ if (__gethostname (hostname, sizeof (hostname)) == -1)
+ strcpy (hostname, NILVALUE);
- /* "%h %e %H:%M:%S " */
- char timestamp[timebuf_size];
- time_t now = time_now ();
- struct tm now_tm;
- __localtime_r (&now, &now_tm);
- __strftime_l (timestamp, sizeof (timestamp), "%h %e %T ", &now_tm,
- _nl_C_locobj_ptr);
+ pid_t pid = LogStat & LOG_PID ? __getpid () : 0;
-#define SYSLOG_HEADER(__pri, __timestamp, __msgoff, pid) \
- "<%d>%s %n%s%s%.0d%s: ", \
- __pri, __timestamp, __msgoff, \
- LogTag == NULL ? __progname : LogTag, \
- pid != 0 ? "[" : "", pid, pid != 0 ? "]" : ""
+#define SYSLOG_HEADER(__pri, __timestamp, __msgoff, __hostname, __pid) \
+ "<%d>1 %s %n%s %s %s%.0d %s %s ", \
+ __pri, /* PRI */ \
+ __timestamp.b, /* TIMESTAMP */ \
+ __msgoff, __hostname, /* HOSTNAME */ \
+ LogTag == NULL ? __progname : LogTag, /* APP-NAME */ \
+ NILVALUE + !!__pid, __pid, /* PROCID */ \
+ NILVALUE, /* MSGID */ \
+ NILVALUE /* STRUCT-DATA */
/* Try to use a static buffer as an optimization. */
+ enum { bufs_size = 1024 };
char bufs[bufs_size];
int l = __snprintf (bufs, sizeof bufs,
- SYSLOG_HEADER (pri, timestamp, &msgoff, pid));
+ SYSLOG_HEADER (pri, timestamp, &msgoff, hostname, pid));
if (l < sizeof (bufs))
{
va_list apc;
@@ -205,7 +238,7 @@ __vsyslog_internal(int pri, const char *fmt, va_list ap,
if (f != NULL)
{
__fsetlocking (f, FSETLOCKING_BYCALLER);
- fprintf (f, SYSLOG_HEADER (pri, timestamp, &msgoff, pid));
+ fprintf (f, SYSLOG_HEADER (pri, timestamp, &msgoff, hostname, pid));
/* Restore errno for %m format. */
__set_errno (saved_errno);
__vfprintf_internal (f, fmt, ap, mode_flags);
diff --git a/misc/tst-syslog.c b/misc/tst-syslog.c
index 8505178616..7b78b0c619 100644
--- a/misc/tst-syslog.c
+++ b/misc/tst-syslog.c
@@ -18,6 +18,7 @@
#include <array_length.h>
#include <fcntl.h>
+#include <intprops.h>
#include <paths.h>
#include <netinet/in.h>
#include <support/capture_subprocess.h>
@@ -201,7 +202,7 @@ check_openlog_message (const struct msg_t *msg, int msgnum,
{
if (options & LOG_PID)
TEST_COMPARE (msg->pid, pid);
- TEST_COMPARE_STRING (msg->ident, expected_ident);
+ TEST_COMPARE_STRING (msg->ident, OPENLOG_IDENT);
TEST_COMPARE (msg->facility, LOG_LOCAL0);
}
else if (msgnum < 2 * array_length (priorities))
@@ -212,28 +213,25 @@ check_openlog_message (const struct msg_t *msg, int msgnum,
return true;
}
+#define NILVALUE "-"
+
static struct msg_t
parse_syslog_msg (const char *msg)
{
struct msg_t r = { .pid = -1 };
int number;
+ char procid[INT_BUFSIZE_BOUND (pid_t)];
/* The message in the form:
<179>Apr 8 14:51:19 tst-syslog: syslog message 176 3 */
- int n = sscanf (msg, "<%3d>%*s %*d %*d:%*d:%*d %32s %64s %*d %*d",
- &number, r.ident, r.msg);
- TEST_COMPARE (n, 3);
+ int n = sscanf (msg, "<%6d>1 %*s %*s %32s %s - - %s",
+ &number, r.ident, procid, r.msg);
+ TEST_COMPARE (n, 4);
r.facility = number & LOG_FACMASK;
r.priority = number & LOG_PRIMASK;
- char *pid_start = strchr (r.ident, '[');
- if (pid_start != NULL)
- {
- char *pid_end = strchr (r.ident, ']');
- if (pid_end != NULL)
- r.pid = strtoul (pid_start + 1, NULL, 10);
- }
+ r.pid = strcmp (procid, NILVALUE) == 0 ? 0 : strtoul (procid, NULL, 10);
return r;
}
@@ -246,9 +244,9 @@ parse_syslog_console (const char *msg)
struct msg_t r;
/* The message in the form:
- openlog_ident: syslog_message 128 0 */
- int n = sscanf (msg, "%32s %64s %d %d",
- r.ident, r.msg, &facility, &priority);
+ mymachine openlog_ident PID - syslog_message 128 0 */
+ int n = sscanf (msg, "%*s %32s %*s - - %s %d %d",
+ r.ident, r.msg, &facility, &priority);
TEST_COMPARE (n, 4);
r.facility = facility;
@@ -384,7 +382,7 @@ check_syslog_console_read (FILE *fp)
while (fgets (buf, sizeof (buf), fp) != NULL)
{
struct msg_t msg = parse_syslog_console (buf);
- TEST_COMPARE_STRING (msg.ident, OPENLOG_IDENT ":");
+ TEST_COMPARE_STRING (msg.ident, OPENLOG_IDENT);
TEST_COMPARE (msg.priority, priorities[msgnum]);
TEST_COMPARE (msg.facility, LOG_LOCAL0);
--
2.32.0
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