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diff --git a/src/util/msg_logger.c b/src/util/msg_logger.c
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+/*++
+/* NAME
+/* msg_logger 3
+/* SUMMARY
+/* direct diagnostics to logger service
+/* SYNOPSIS
+/* #include <msg_logger.h>
+/*
+/* void msg_logger_init(
+/* const char *progname,
+/* const char *hostname,
+/* const char *unix_path,
+/* void (*fallback)(const char *))
+/*
+/* void msg_logger_control(
+/* int key,...)
+/* DESCRIPTION
+/* This module implements support to report msg(3) diagnostics
+/* through a logger daemon, with an optional fallback mechanism.
+/* The log record format is like traditional syslog:
+/*
+/* .nf
+/* Mmm dd host progname[pid]: text...
+/* .fi
+/*
+/* msg_logger_init() arranges that subsequent msg(3) calls
+/* will write to an internal logging service. This function
+/* may also be used to update msg_logger settings.
+/*
+/* Arguments:
+/* .IP progname
+/* The program name that is prepended to a log record.
+/* .IP hostname
+/* The host name that is prepended to a log record. Only the
+/* first hostname label will be used.
+/* .IP unix_path
+/* Pathname of a unix-domain datagram service endpoint. A
+/* typical use case is the pathname of the postlog socket.
+/* .IP fallback
+/* Null pointer, or pointer to function that will be called
+/* with a formatted message when the logger service is not
+/* (yet) available. A typical use case is to pass the record
+/* to the logwriter(3) module.
+/* .PP
+/* msg_logger_control() makes adjustments to the msg_logger
+/* client. These adjustments remain in effect until the next
+/* msg_logger_init() or msg_logger_control() call. The arguments
+/* are a list of macros with zero or more arguments, terminated
+/* with CA_MSG_LOGGER_CTL_END which has none. The following
+/* lists the names and the types of the corresponding value
+/* arguments.
+/*
+/* Arguments:
+/* .IP CA_MSG_LOGGER_CTL_FALLBACK_ONLY
+/* Disable the logging socket, and use the fallback function
+/* only. This remains in effect until the next msg_logger_init()
+/* call.
+/* .IP CA_MSG_LOGGER_CTL_FALLBACK(void (*)(const char *))
+/* Override the fallback setting (see above) with the specified
+/* function pointer. This remains in effect until the next
+/* msg_logger_init() or msg_logger_control() call.
+/* .IP CA_MSG_LOGGER_CTL_DISABLE
+/* Disable the msg_logger. This remains in effect until the
+/* next msg_logger_init() call.
+/* SEE ALSO
+/* msg(3) diagnostics module
+/* BUGS
+/* Output records are truncated to ~2000 characters, because
+/* unlimited logging is a liability.
+/* LICENSE
+/* .ad
+/* .fi
+/* The Secure Mailer license must be distributed with this software.
+/* AUTHOR(S)
+/* Wietse Venema
+/* Google, Inc.
+/* 111 8th Avenue
+/* New York, NY 10011, USA
+/*--*/
+
+ /*
+ * System libraries.
+ */
+#include <sys_defs.h>
+#include <sys/socket.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <unistd.h>
+
+ /*
+ * Application-specific.
+ */
+#include <connect.h>
+#include <logwriter.h>
+#include <msg.h>
+#include <msg_logger.h>
+#include <msg_output.h>
+#include <mymalloc.h>
+#include <safe.h>
+#include <vstream.h>
+#include <vstring.h>
+
+ /*
+ * Saved state from msg_logger_init().
+ */
+static char *msg_logger_progname;
+static char *msg_logger_hostname;
+static char *msg_logger_unix_path;
+static void (*msg_logger_fallback_fn) (const char *);
+static int msg_logger_fallback_only_override = 0;
+static int msg_logger_enable = 0;
+
+ /*
+ * Other state.
+ */
+#define MSG_LOGGER_SOCK_NONE (-1)
+
+static VSTRING *msg_logger_buf;
+static int msg_logger_sock = MSG_LOGGER_SOCK_NONE;
+
+ /*
+ * Safety limit.
+ */
+#define MSG_LOGGER_RECLEN 2000
+
+ /*
+ * SLMs.
+ */
+#define STR(x) vstring_str(x)
+#define LEN(x) VSTRING_LEN(x)
+
+
+/* msg_logger_print - log info to service or file */
+
+static void msg_logger_print(int level, const char *text)
+{
+ time_t now;
+ struct tm *lt;
+ ssize_t len;
+
+ /*
+ * This test is simple enough that we don't bother with unregistering the
+ * msg_logger_print() function.
+ */
+ if (msg_logger_enable == 0)
+ return;
+
+ /*
+ * TODO: this should be a reusable NAME_CODE table plus lookup function.
+ */
+ static int log_level[] = {
+ MSG_INFO, MSG_WARN, MSG_ERROR, MSG_FATAL, MSG_PANIC,
+ };
+ static char *severity_name[] = {
+ "info", "warning", "error", "fatal", "panic",
+ };
+
+ /*
+ * Note: there is code in postlogd(8) that attempts to strip off
+ * information that is prepended here. If the formatting below is
+ * changed, then postlogd needs to be updated as well.
+ */
+
+ /*
+ * Format the time stamp.
+ */
+ if (time(&now) < 0)
+ msg_fatal("no time: %m");
+ lt = localtime(&now);
+ VSTRING_RESET(msg_logger_buf);
+ if ((len = strftime(vstring_str(msg_logger_buf),
+ vstring_avail(msg_logger_buf),
+ "%b %d %H:%M:%S ", lt)) == 0)
+ msg_fatal("strftime: %m");
+ vstring_set_payload_size(msg_logger_buf, len);
+
+ /*
+ * Format the host name (first name label only).
+ */
+ vstring_sprintf_append(msg_logger_buf, "%.*s ",
+ (int) strcspn(msg_logger_hostname, "."),
+ msg_logger_hostname);
+
+ /*
+ * Format the message.
+ */
+ if (level < 0 || level >= (int) (sizeof(log_level) / sizeof(log_level[0])))
+ msg_panic("msg_logger_print: invalid severity level: %d", level);
+
+ if (level == MSG_INFO) {
+ vstring_sprintf_append(msg_logger_buf, "%s[%ld]: %.*s",
+ msg_logger_progname, (long) getpid(),
+ (int) MSG_LOGGER_RECLEN, text);
+ } else {
+ vstring_sprintf_append(msg_logger_buf, "%s[%ld]: %s: %.*s",
+ msg_logger_progname, (long) getpid(),
+ severity_name[level], (int) MSG_LOGGER_RECLEN, text);
+ }
+
+ /*
+ * Connect to logging service, or fall back to direct log. Many systems
+ * will report ENOENT if the endpoint does not exist, ECONNREFUSED if no
+ * server has opened the endpoint.
+ */
+ if (msg_logger_fallback_only_override == 0
+ && msg_logger_sock == MSG_LOGGER_SOCK_NONE) {
+ msg_logger_sock = unix_dgram_connect(msg_logger_unix_path, BLOCKING);
+ if (msg_logger_sock >= 0)
+ close_on_exec(msg_logger_sock, CLOSE_ON_EXEC);
+ }
+ if (msg_logger_sock != MSG_LOGGER_SOCK_NONE) {
+ send(msg_logger_sock, STR(msg_logger_buf), LEN(msg_logger_buf), 0);
+ } else if (msg_logger_fallback_fn) {
+ msg_logger_fallback_fn(STR(msg_logger_buf));
+ }
+}
+
+/* msg_logger_init - initialize */
+
+void msg_logger_init(const char *progname, const char *hostname,
+ const char *unix_path, void (*fallback) (const char *))
+{
+ static int first_call = 1;
+ extern char **environ;
+
+ /*
+ * XXX If this program is set-gid, then TZ must not be trusted. This
+ * scrubbing code is in the wrong place.
+ */
+ if (first_call) {
+ if (unsafe())
+ while (getenv("TZ")) /* There may be multiple. */
+ if (unsetenv("TZ") < 0) { /* Desperate measures. */
+ environ[0] = 0;
+ msg_fatal("unsetenv: %m");
+ }
+ tzset();
+ }
+
+ /*
+ * Save the request info. Use free-after-update because this data will be
+ * accessed when mystrdup() runs out of memory.
+ */
+#define UPDATE_AND_FREE(dst, src) do { \
+ if ((dst) == 0 || strcmp((dst), (src)) != 0) { \
+ char *_bak = (dst); \
+ (dst) = mystrdup(src); \
+ if ((_bak)) myfree(_bak); \
+ } \
+ } while (0)
+
+ UPDATE_AND_FREE(msg_logger_progname, progname);
+ UPDATE_AND_FREE(msg_logger_hostname, hostname);
+ UPDATE_AND_FREE(msg_logger_unix_path, unix_path);
+ msg_logger_fallback_fn = fallback;
+
+ /*
+ * One-time activity: register the output handler, and allocate a buffer.
+ */
+ if (first_call) {
+ first_call = 0;
+ msg_output(msg_logger_print);
+ msg_logger_buf = vstring_alloc(2048);
+ }
+
+ /*
+ * Always.
+ */
+ msg_logger_enable = 1;
+ msg_logger_fallback_only_override = 0;
+}
+
+/* msg_logger_control - tweak the client */
+
+void msg_logger_control(int name,...)
+{
+ const char *myname = "msg_logger_control";
+ va_list ap;
+
+ /*
+ * Overrides remain in effect until the next msg_logger_init() or
+ * msg_logger_control() call,
+ */
+ for (va_start(ap, name); name != MSG_LOGGER_CTL_END; name = va_arg(ap, int)) {
+ switch (name) {
+ case MSG_LOGGER_CTL_FALLBACK_ONLY:
+ msg_logger_fallback_only_override = 1;
+ if (msg_logger_sock != MSG_LOGGER_SOCK_NONE) {
+ (void) close(msg_logger_sock);
+ msg_logger_sock = MSG_LOGGER_SOCK_NONE;
+ }
+ break;
+ case MSG_LOGGER_CTL_FALLBACK_FN:
+ msg_logger_fallback_fn = va_arg(ap, MSG_LOGGER_FALLBACK_FN);
+ break;
+ case MSG_LOGGER_CTL_DISABLE:
+ msg_logger_enable = 0;
+ break;
+ default:
+ msg_panic("%s: bad name %d", myname, name);
+ }
+ }
+ va_end(ap);
+}
+
+#ifdef TEST
+
+ /*
+ * Proof-of-concept program to test the msg_logger module.
+ *
+ * Usage: msg_logger hostname unix_path fallback_path text...
+ */
+static char *fallback_path;
+
+static void fallback(const char *msg)
+{
+ if (logwriter_one_shot(fallback_path, msg) != 0)
+ msg_fatal("unable to fall back to directly write %s: %m",
+ fallback_path);
+}
+
+int main(int argc, char **argv)
+{
+ VSTRING *vp = vstring_alloc(256);
+
+ if (argc < 4)
+ msg_fatal("usage: %s host port path text to log", argv[0]);
+ msg_logger_init(argv[0], argv[1], argv[2], fallback);
+ fallback_path = argv[3];
+ argc -= 3;
+ argv += 3;
+ while (--argc && *++argv) {
+ vstring_strcat(vp, *argv);
+ if (argv[1])
+ vstring_strcat(vp, " ");
+ }
+ msg_warn("static text");
+ msg_warn("dynamic text: >%s<", vstring_str(vp));
+ msg_warn("dynamic numeric: >%d<", 42);
+ msg_warn("error text: >%m<");
+ msg_warn("dynamic: >%s<: error: >%m<", vstring_str(vp));
+ vstring_free(vp);
+ return (0);
+}
+
+#endif