logger.c

/*-
 * SSLsplit - transparent SSL/TLS interception
 * https://www.roe.ch/SSLsplit
 *
 * Copyright (c) 2009-2019, Daniel Roethlisberger <daniel@roe.ch>.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER AND CONTRIBUTORS ``AS IS''
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include "logger.h"

#include "thrqueue.h"
#include "logbuf.h"

#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>

/*
 * Logger for multithreaded environments.  Disk writes are executed in a
 * writer thread.  Logging threads submit buffers to be logged by adding
 * them to the thrqueue.  Logging threads may block on the pthread mutex
 * of the thrqueue, but not on disk writes.
 */

struct logger {
	pthread_t thr;
	logger_reopen_func_t reopen;
	logger_open_func_t open;
	logger_close_func_t close;
	logger_prep_func_t prep;
	logger_write_func_t write;
	logger_except_func_t except;
	thrqueue_t *queue;
};

static void
logger_clear(logger_t *logger)
{
	memset(logger, 0, sizeof(logger_t));
}

/*
 * Create new logger with a set of specific function callbacks:
 *
 * reopenfunc:  handle SIGHUP for the log by reopening all open files across
 *              multiple connections
 * openfunc:    open a new log for a new connection
 * closefunc:   close a log for a connection
 * writefunc:   write a single logbuf to the log
 * prepfunc:    prepare a log buffer before adding it to the logbuffer's queue
 * exceptfunc:  called after failed callback operations
 *
 * All callbacks except prepfunc will be executed in the logger's writer
 * thread, not in the thread calling logger_submit().  Prepfunc will be called
 * in the thread calling logger_submit().
 */
logger_t *
logger_new(logger_reopen_func_t reopenfunc, logger_open_func_t openfunc,
           logger_close_func_t closefunc, logger_write_func_t writefunc,
           logger_prep_func_t prepfunc, logger_except_func_t exceptfunc)
{
	logger_t *logger;

	logger = malloc(sizeof(logger_t));
	if (!logger)
		return NULL;
	logger_clear(logger);
	logger->reopen = reopenfunc;
	logger->open = openfunc;
	logger->close = closefunc;
	logger->write = writefunc;
	logger->prep = prepfunc;
	logger->except = exceptfunc;
	logger->queue = NULL;
	return logger;
}

/*
 * Free the logger data structures.  Caller must call logger_stop()
 * or logger_leave() and logger_join() prior to freeing.
 */
void
logger_free(logger_t *logger) {
	if (logger->queue) {
		thrqueue_free(logger->queue);
	}
	free(logger);
}

/*
 * Submit a buffer to be logged by the logger thread.
 * Calls the prep callback from within the calling tread before submission.
 * Buffer guaranteed to be freed after logging completes or on failure.
 * Returns -1 on error, 0 on success (including logging a NULL logbuf, which
 * is a no-op).
 */
int
logger_submit(logger_t *logger, void *fh, unsigned long prepflags,
              logbuf_t *lb)
{
	if (lb) {
		lb->fh = fh;
		logbuf_ctl_clear(lb);
	}
	if (logger->prep)
		lb = logger->prep(fh, prepflags, lb);
	/* If we got passed lb == NULL and prep callback did not replace it
	 * with an actual log buffer, stop here. */
	if (!lb)
		return 0;
	if (thrqueue_enqueue(logger->queue, lb)) {
		return 0;
	} else {
		logbuf_free(lb);
		return -1;
	}
}

/*
 * Submit a log reopen event to the logger thread.
 */
int
logger_reopen(logger_t *logger)
{
	logbuf_t *lb;

	if (!logger->reopen)
		return 0;

	if (!(lb = logbuf_new(NULL, 0, NULL)))
		return -1;
	logbuf_ctl_set(lb, LBFLAG_REOPEN);
	return thrqueue_enqueue(logger->queue, lb) ? 0 : -1;
}

/*
 * Submit a file open event to the logger thread.
 * fh is the file handle; an opaque unique address identifying the new file.
 * If no open callback is configured, returns successfully.
 * Returns 0 on success, -1 on failure.
 */
int
logger_open(logger_t *logger, void *fh)
{
	logbuf_t *lb;

	if (!logger->open)
		return 0;

	if (!(lb = logbuf_new(NULL, 0, NULL)))
		return -1;
	lb->fh = fh;
	logbuf_ctl_set(lb, LBFLAG_OPEN);
	return thrqueue_enqueue(logger->queue, lb) ? 0 : -1;
}

/*
 * Submit a file close event to the logger thread.
 * If no close callback is configured, returns successfully.
 * Returns 0 on success, -1 on failure.
 */
int
logger_close(logger_t *logger, void *fh, unsigned long ctl)
{
	logbuf_t *lb;

	if (!logger->close)
		return 0;

	if (!(lb = logbuf_new(NULL, 0, NULL)))
		return -1;
	lb->fh = fh;
	lb->ctl = ctl;
	logbuf_ctl_set(lb, LBFLAG_CLOSE);
	return thrqueue_enqueue(logger->queue, lb) ? 0 : -1;
}

/*
 * Logger thread main function.
 */
static void *
logger_thread(void *arg)
{
	logger_t *logger = arg;
	logbuf_t *lb;
	int e = 0;

	while ((lb = thrqueue_dequeue(logger->queue))) {
		if (logbuf_ctl_isset(lb, LBFLAG_REOPEN)) {
			if (logger->reopen() != 0)
				e = 1;
			logbuf_free(lb);
		} else if (logbuf_ctl_isset(lb, LBFLAG_OPEN)) {
			if (logger->open(lb->fh) != 0)
				e = 1;
			logbuf_free(lb);
		} else if (logbuf_ctl_isset(lb, LBFLAG_CLOSE)) {
			logger->close(lb->fh, lb->ctl);
			logbuf_free(lb);
		} else {
			if (logbuf_write_free(lb, logger->write) < 0)
				e = 1;
		}

		if (e && logger->except) {
			logger->except();
		}
	}

	return NULL;
}

/*
 * Start the logger's write thread.
 */
int
logger_start(logger_t *logger) {
	int rv;

	if (logger->queue) {
		thrqueue_free(logger->queue);
	}
	logger->queue = thrqueue_new(1024);

	rv = pthread_create(&logger->thr, NULL, logger_thread, logger);
	if (rv)
		return -1;
	sched_yield();
	return 0;
}

/*
 * Tell the logger's write thread to write all pending write requests
 * and then exit.  Don't wait for the logger to exit.
 */
void
logger_leave(logger_t *logger) {
	thrqueue_unblock_dequeue(logger->queue);
	sched_yield();
}

/*
 * Wait for the logger to exit.
 */
int
logger_join(logger_t *logger) {
	int rv;

	rv = pthread_join(logger->thr, NULL);
	if (rv)
		return -1;
	return 0;
}

/*
 * Tell the logger's write thread to write all pending write requests
 * and then exit; wait for the logger to exit.
 */
int
logger_stop(logger_t *logger) {
	logger_leave(logger);
	return logger_join(logger);
}

/*
 * Generic print to a logger.  These functions should be called by the
 * actual worker thread(s) doing network I/O.
 *
 * _printf(), _print() and _write() copy the input buffers.
 * _ncprint() and _ncwrite() will free() the input buffers.
 *
 * The file descriptor argument is a virtual or real system file descriptor
 * used for multiplexing write requests to several files over the same
 * logger.  This argument is passed to the write handler as-is and is not
 * interpreted or used by the logger itself in any way.
 *
 * All of the functions return 0 on success, -1 on failure.
 */
int
logger_printf(logger_t *logger, void *fh, unsigned long prepflags,
              const char *fmt, ...)
{
	va_list ap;
	logbuf_t *lb;

	if (!(lb = logbuf_new(NULL, 0, NULL)))
		return -1;
	va_start(ap, fmt);
	lb->sz = vasprintf((char**)&lb->buf, fmt, ap);
	va_end(ap);
	if (lb->sz < 0) {
		logbuf_free(lb);
		return -1;
	}
	return logger_submit(logger, fh, prepflags, lb);
}
int
logger_write(logger_t *logger, void *fh, unsigned long prepflags,
             const void *buf, size_t sz)
{
	logbuf_t *lb;

	if (!(lb = logbuf_new_copy(buf, sz, NULL)))
		return -1;
	return logger_submit(logger, fh, prepflags, lb);
}
int
logger_print(logger_t *logger, void *fh, unsigned long prepflags,
             const char *s)
{
	logbuf_t *lb;

	if (!(lb = logbuf_new_copy(s, strlen(s), NULL)))
		return -1;
	return logger_submit(logger, fh, prepflags, lb);
}
int
logger_write_freebuf(logger_t *logger, void *fh, unsigned long prepflags,
                     void *buf, size_t sz)
{
	logbuf_t *lb;

	if (!(lb = logbuf_new(buf, sz, NULL)))
		return -1;
	return logger_submit(logger, fh, prepflags, lb);
}
int
logger_print_freebuf(logger_t *logger, void *fh, unsigned long prepflags,
                     char *s)
{
	return logger_write_freebuf(logger, fh, prepflags, s, strlen(s));
}

/* vim: set noet ft=c: */