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Snort_AIPreproc/alert_parser.c

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/*
* =====================================================================================
*
* Filename: alert_parser.c
*
* Description: Managing the parsing of Snort's alert file
*
* Version: 0.1
* Created: 08/08/2010 09:21:57
* Revision: none
* Compiler: gcc
*
* Author: BlackLight (http://0x00.ath.cx), <blacklight@autistici.org>
* Licence: GNU GPL v.3
* Company: DO WHAT YOU WANT CAUSE A PIRATE IS FREE, YOU ARE A PIRATE!
*
* =====================================================================================
*/
#include "spp_ai.h"
#include <pthread.h>
#include <stdio.h>
#include <sys/stat.h>
#include <time.h>
#include <unistd.h>
#ifdef LINUX
#include <sys/inotify.h>
#endif
/** \defgroup alert_parser Parse the alert log into binary structures
* @{ */
PRIVATE AI_snort_alert *alerts = NULL;
PRIVATE FILE *alert_fp = NULL;
PRIVATE pthread_mutex_t alert_mutex;
PRIVATE pthread_mutex_t alerts_pool_mutex;
AI_snort_alert **alerts_pool = NULL;
unsigned int alerts_pool_count = 0;
/**
* \brief Serialize the pool of alerts in a separated thread
* \param arg void* pointer to the alert to be added to the pool, if any
*/
void*
AI_serializer_thread ( void *arg )
{
unsigned int i = 0;
AI_snort_alert *alert = NULL;
if ( arg )
{
alert = ( AI_snort_alert* ) arg;
pthread_mutex_lock ( &alerts_pool_mutex );
alerts_pool [ alerts_pool_count++ ] = alert;
pthread_mutex_unlock ( &alerts_pool_mutex );
}
if ( !arg || ( arg && alerts_pool_count >= config->alert_bufsize ))
{
pthread_mutex_lock ( &alerts_pool_mutex );
AI_serialize_alerts ( alerts_pool, alerts_pool_count );
for ( i=0; i < alerts_pool_count; i++ )
{
alerts_pool[i] = NULL;
}
alerts_pool_count = 0;
pthread_mutex_unlock ( &alerts_pool_mutex );
}
pthread_exit ((void*) 0);
return (void*) 0;
} /* ----- end of function AI_serializer_thread ----- */
/**
* \brief Thread for managing the buffer of alerts and serialize them at constant intervals
*/
void*
AI_alerts_pool_thread ( void *arg )
{
pthread_t serializer_thread;
while ( 1 )
{
sleep ( config->alertSerializationInterval );
if ( !alerts_pool || alerts_pool_count == 0 )
continue;
if ( pthread_create ( &serializer_thread, NULL, AI_serializer_thread, NULL ) != 0 )
AI_fatal_err ( "Failed to create the alerts' serializer thread", __FILE__, __LINE__ );
}
pthread_exit ((void*) 0);
return (void*) 0;
} /* ----- end of function AI_alerts_pool_thread ----- */
/**
* \brief Thread for parsing Snort's alert file
*/
void*
AI_file_alertparser_thread ( void* arg )
{
struct logtime {
unsigned short day;
unsigned short month;
unsigned short year;
unsigned short hour;
unsigned short min;
unsigned short sec;
};
int i;
#ifdef LINUX
int ifd;
int wd;
struct stat st;
#else
int fd = -1;
struct stat stats;
time_t last_mod_time = (time_t) 0;
#endif
int nmatches = 0;
char line[8192];
char strtime[256];
char **matches = NULL;
time_t stamp;
struct tm *_tm;
struct logtime ltime;
struct pkt_key key;
struct pkt_info *info;
AI_snort_alert *alert = NULL;
AI_snort_alert *tmp = NULL;
BOOL in_alert = false;
pthread_t alerts_pool_thread;
pthread_t serializer_thread;
pthread_t db_thread;
/* Initialize the mutex lock, so nobody can read the alerts while we write there */
pthread_mutex_init ( &alert_mutex, NULL );
/* Initialize the mutex on the alerts' pool, so that an only thread per time can write there */
pthread_mutex_init ( &alerts_pool_mutex, NULL );
/* Initialize the pool of alerts to be passed to the serialization thread */
if ( !( alerts_pool = ( AI_snort_alert** ) malloc ( config->alert_bufsize * sizeof ( AI_snort_alert* ))))
AI_fatal_err ( "Fatal dynamic memory allocation error", __FILE__, __LINE__ );
for ( i=0; i < config->alert_bufsize; i++ )
alerts_pool[i] = NULL;
/* Initialize the thread for managing the serialization of alerts' pool */
if ( pthread_create ( &alerts_pool_thread, NULL, AI_alerts_pool_thread, NULL ) != 0 )
AI_fatal_err ( "Failed to create the alerts' pool management thread", __FILE__, __LINE__ );
while ( 1 )
{
#ifdef LINUX
if (( ifd = inotify_init() ) < 0 )
{
AI_fatal_err ( "Could not initialize an inotify object on the alert log file", __FILE__, __LINE__ );
}
if ( stat ( config->alertfile, &st ) < 0 )
{
if (( wd = inotify_add_watch ( ifd, config->alertfile, IN_CREATE )) < 0 )
{
AI_fatal_err ( "Could not initialize a watch descriptor on the alert log file", __FILE__, __LINE__ );
}
read ( ifd, line, sizeof(line) );
inotify_rm_watch ( ifd, wd );
} else {
if ( !alert_fp )
{
if ( ! (alert_fp = fopen ( config->alertfile, "r" )) )
{
AI_fatal_err ( "Could not open alert log file for reading", __FILE__, __LINE__ );
}
}
}
if (( wd = inotify_add_watch ( ifd, config->alertfile, IN_MODIFY )) < 0 )
{
AI_fatal_err ( "Could not initialize a watch descriptor on the alert log file", __FILE__, __LINE__ );
}
fseek ( alert_fp, 0, SEEK_END );
read ( ifd, line, sizeof(line) );
inotify_rm_watch ( ifd, wd );
close ( ifd );
#else
/*
* Under Apple environments we don't have inotify capabilities, so use polling instead.
* TODO: Use FSEvent.
*/
if ( !alert_fp )
{
if ( ! (alert_fp = fopen ( config->alertfile, "r" )) )
{
AI_fatal_err ( "Could not open alert log file for reading", __FILE__, __LINE__ );
}
else if( fd == -1 ){
/*
* Convert a FILE * to an integer file descriptor to be used with fstat.
*/
fd = fileno(alert_fp);
}
}
/*
* Cause the thread to wait until a new file modification (a new alert).
*/
while( stats.st_mtime == last_mod_time ){
usleep(100);
fstats( fd, &stats );
}
/*
* The first time the thread is called, the flow exits instantly from the while,
* so this first time the stats structure has to be initialized properly.
*/
if( last_mod_time == (time_t)0 ){
fstats( fd, &stats );
}
last_mod_time = stats.st_mtime;
fseek ( alert_fp, 0, SEEK_END );
#endif
while ( !feof ( alert_fp ))
{
fgets ( line, sizeof(line), alert_fp );
for ( i = strlen(line)-1;
i >= 0 && ( line[i] == '\n' || line[i] == '\r' || line[i] == '\t' || line[i] == ' ' );
i++ )
{
line[i] = 0;
}
if ( strlen(line) == 0 )
{
if ( in_alert )
{
if ( alert->ip_src_addr && ( alert->ip_proto == IPPROTO_TCP || alert->ip_proto == IPPROTO_UDP ))
{
key.src_ip = alert->ip_src_addr;
key.dst_port = alert->tcp_dst_port;
if ( alert->ip_proto == IPPROTO_TCP )
{
if (( info = AI_get_stream_by_key ( key ) ))
{
AI_set_stream_observed ( key );
alert->stream = info;
}
}
}
if ( alerts == NULL )
{
alerts = alert;
alerts->next = NULL;
} else {
for ( tmp = alerts; tmp->next; tmp = tmp->next );
tmp->next = alert;
}
if ( pthread_create ( &serializer_thread, NULL, AI_serializer_thread, alert ) != 0 )
AI_fatal_err ( "Failed to create the alerts' serializer thread", __FILE__, __LINE__ );
if ( config->outdbtype != outdb_none )
{
if ( pthread_create ( &db_thread, NULL, AI_store_alert_to_db_thread, alert ) != 0 )
AI_fatal_err ( "Failed to create the alert to db storing thread", __FILE__, __LINE__ );
}
in_alert = false;
alert = NULL;
}
continue;
}
if ( !in_alert )
{
pthread_mutex_lock ( &alert_mutex );
if ( preg_match ( "^\\[\\*\\*\\]\\s*\\[([0-9]+):([0-9]+):([0-9]+)\\]\\s*(.*)\\s*\\[\\*\\*\\]$", line, &matches, &nmatches ) > 0 )
{
in_alert = true;
if ( !( alert = ( AI_snort_alert* ) malloc ( sizeof( AI_snort_alert ))))
{
AI_fatal_err ( "Fatal dynamic memory allocation error", __FILE__, __LINE__ );
}
memset ( alert, 0, sizeof(AI_snort_alert) );
alert->gid = strtoul ( matches[0], NULL, 10 );
alert->sid = strtoul ( matches[1], NULL, 10 );
alert->rev = strtoul ( matches[2], NULL, 10 );
alert->desc = strdup ( matches[3] );
for ( i=0; i < nmatches; i++ )
free ( matches[i] );
free ( matches );
matches = NULL;
} else {
AI_fatal_err ( "Parse error: a line in the alert log cannot be associated to an alert block", __FILE__, __LINE__ );
}
} else if ( preg_match ( "\\[Priority:\\s*([0-9]+)\\]", line, &matches, &nmatches) > 0 ) {
alert->priority = (unsigned short) strtoul ( matches[0], NULL, 10 );
for ( i=0; i < nmatches; i++ )
free ( matches[i] );
free ( matches );
matches = NULL;
if ( preg_match ( "\\[Classification:\\s*([^\\]]+)\\]", line, &matches, &nmatches) > 0 )
{
alert->classification = strdup ( matches[0] );
for ( i=0; i < nmatches; i++ )
free ( matches[i] );
free ( matches );
matches = NULL;
}
} else if ( preg_match ( "^([0-9]{2})/([0-9]{2})-([0-9]{2}):([0-9]{2}):([0-9]{2})\\.[0-9]+\\s+([0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}):([0-9]{1,5})\\s*"
"->\\s*([0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}):([0-9]{1,5})",
line, &matches, &nmatches ) > 0 ) {
stamp = time(NULL);
_tm = localtime ( &stamp );
ltime.year = (unsigned short) _tm->tm_year + 1900;
ltime.day = (unsigned short) strtoul ( matches[0], NULL, 10 );
ltime.month = (unsigned short) strtoul ( matches[1], NULL, 10 );
ltime.hour = (unsigned short) strtoul ( matches[2], NULL, 10 );
ltime.min = (unsigned short) strtoul ( matches[3], NULL, 10 );
ltime.sec = (unsigned short) strtoul ( matches[4], NULL, 10 );
snprintf ( strtime, sizeof(strtime), "%02hu/%02hu/%04hu, %02hu:%02hu:%02hu",
ltime.day, ltime.month, ltime.year, ltime.hour, ltime.min, ltime.sec );
strptime ( strtime, "%d/%m/%Y, %H:%M:%S", _tm );
alert->timestamp = mktime ( _tm );
alert->ip_src_addr = inet_addr ( matches[5] );
alert->ip_dst_addr = inet_addr ( matches[7] );
alert->tcp_src_port = htons ( atoi( matches[6] ));
alert->tcp_dst_port = htons ( atoi( matches[8] ));
for ( i=0; i < nmatches; i++ )
free ( matches[i] );
free ( matches );
matches = NULL;
} else if ( preg_match ( "^([0-9]{2})/([0-9]{2})-([0-9]{2}):([0-9]{2}):([0-9]{2})\\.[0-9]+\\s+([0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3})\\s*"
"->\\s*([0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3})",
line, &matches, &nmatches ) > 0 ) {
stamp = time(NULL);
_tm = localtime ( &stamp );
ltime.year = (unsigned short) _tm->tm_year + 1900;
ltime.day = (unsigned short) strtoul ( matches[0], NULL, 10 );
ltime.month = (unsigned short) strtoul ( matches[1], NULL, 10 );
ltime.hour = (unsigned short) strtoul ( matches[2], NULL, 10 );
ltime.min = (unsigned short) strtoul ( matches[3], NULL, 10 );
ltime.sec = (unsigned short) strtoul ( matches[4], NULL, 10 );
snprintf ( strtime, sizeof(strtime), "%02hu/%02hu/%04hu, %02hu:%02hu:%02hu",
ltime.day, ltime.month, ltime.year, ltime.hour, ltime.min, ltime.sec );
strptime ( strtime, "%d/%m/%Y, %H:%M:%S", _tm );
alert->timestamp = mktime ( _tm );
alert->ip_src_addr = inet_addr ( matches[5] );
alert->ip_dst_addr = inet_addr ( matches[6] );
for ( i=0; i < nmatches; i++ )
free ( matches[i] );
free ( matches );
matches = NULL;
} else if ( preg_match ( "^([^\\s+]+)\\s+TTL:\\s*([0-9]+)\\s+TOS:\\s*0x([0-9A-F]+)\\s+ID:\\s*([0-9]+)\\s+IpLen:\\s*([0-9]+)",
line, &matches, &nmatches ) > 0 ) {
if ( !strcasecmp ( matches[0], "tcp" ) ) {
alert->ip_proto = IPPROTO_TCP;
} else if ( !strcasecmp ( matches[0], "udp" ) ) {
alert->ip_proto = IPPROTO_UDP;
} else if ( !strcasecmp ( matches[0], "icmp" ) ) {
alert->ip_proto = IPPROTO_ICMP;
} else {
alert->ip_proto = IPPROTO_NONE;
}
alert->ip_ttl = htons ( (uint16_t) strtoul ( matches[1], NULL, 10 ));
alert->ip_tos = htons ( (uint16_t) strtoul ( matches[2], NULL, 16 ));
alert->ip_id = htons ( (uint16_t) strtoul ( matches[3], NULL, 10 ));
alert->ip_len = htons ( (uint16_t) strtoul ( matches[4], NULL, 10 ));
for ( i=0; i < nmatches; i++ )
free ( matches[i] );
free ( matches );
matches = NULL;
} else if ( preg_match ( "^([\\*CEUAPRSF]{8})\\s+Seq:\\s*0x([0-9A-F]+)\\s+Ack:\\s*0x([0-9A-F]+)\\s+Win:\\s*0x([0-9A-F]+)\\s+TcpLen:\\s*([0-9]+)",
line, &matches, &nmatches ) > 0 ) {
alert->tcp_flags = 0;
alert->tcp_flags |= ( strstr ( matches[0], "C" ) ) ? TCPHEADER_RES1 : 0;
alert->tcp_flags |= ( strstr ( matches[0], "E" ) ) ? TCPHEADER_RES2 : 0;
alert->tcp_flags |= ( strstr ( matches[0], "U" ) ) ? TCPHEADER_URG : 0;
alert->tcp_flags |= ( strstr ( matches[0], "A" ) ) ? TCPHEADER_ACK : 0;
alert->tcp_flags |= ( strstr ( matches[0], "P" ) ) ? TCPHEADER_PUSH : 0;
alert->tcp_flags |= ( strstr ( matches[0], "R" ) ) ? TCPHEADER_RST : 0;
alert->tcp_flags |= ( strstr ( matches[0], "S" ) ) ? TCPHEADER_SYN : 0;
alert->tcp_flags |= ( strstr ( matches[0], "F" ) ) ? TCPHEADER_FIN : 0;
alert->tcp_seq = htonl ( strtoul ( matches[1], NULL, 16 ));
alert->tcp_ack = htonl ( strtoul ( matches[2], NULL, 16 ));
alert->tcp_window = htons ( (uint16_t) strtoul ( matches[3], NULL, 16 ));
alert->tcp_len = htons ( (uint16_t) strtoul ( matches[4], NULL, 10 ));
for ( i=0; i < nmatches; i++ )
free ( matches[i] );
free ( matches );
matches = NULL;
}
}
pthread_mutex_unlock ( &alert_mutex );
}
free ( alerts_pool );
pthread_mutex_destroy ( &alert_mutex );
pthread_exit ((void*) 0 );
return (void*) 0;
} /* ----- end of function AI_file_alertparser_thread ----- */
/**
* \brief Create a copy of the alert log struct (this is done for leaving the alert log structure in this file as read-only)
* \param node Starting node (used for the recursion)
* \return A copy of the alert log linked list
*/
PRIVATE AI_snort_alert*
__AI_copy_alerts ( AI_snort_alert *node )
{
AI_snort_alert *current = NULL, *next = NULL;
if ( !node )
{
return NULL;
}
if ( node->next )
{
next = __AI_copy_alerts ( node->next );
}
if ( !( current = ( AI_snort_alert* ) malloc ( sizeof ( AI_snort_alert )) ))
{
AI_fatal_err ( "Fatal dynamic memory allocation error", __FILE__, __LINE__ );
}
memcpy ( current, node, sizeof ( AI_snort_alert ));
current->next = next;
return current;
} /* ----- end of function __AI_copy_alerts ----- */
/**
* \brief Return the alerts parsed so far as a linked list
* \return An AI_snort_alert pointer identifying the list of alerts
*/
AI_snort_alert*
AI_get_alerts ()
{
AI_snort_alert *alerts_copy;
pthread_mutex_lock ( &alert_mutex );
alerts_copy = __AI_copy_alerts ( alerts );
pthread_mutex_unlock ( &alert_mutex );
return alerts_copy;
} /* ----- end of function AI_get_alerts ----- */
/**
* \brief Deallocate the memory of a log alert linked list
* \param node Linked list to be freed
*/
void
AI_free_alerts ( AI_snort_alert *node )
{
int i;
if ( !node )
return;
if ( node->next )
AI_free_alerts ( node->next );
/* if ( node->grouped_alerts ) */
/* { */
/* for ( i=0; i < node->grouped_alerts_count; i++ ) */
/* { */
/* if ( node->grouped_alerts[i] ) */
/* { */
/* free ( node->grouped_alerts[i] ); */
/* node->grouped_alerts[i] = NULL; */
/* } */
/* } */
/* free ( node->grouped_alerts ); */
/* } */
if ( node->hyperalert )
{
for ( i=0; i < node->hyperalert->n_preconds; i++ )
free ( node->hyperalert->preconds[i] );
free ( node->hyperalert->preconds );
for ( i=0; i < node->hyperalert->n_postconds; i++ )
free ( node->hyperalert->postconds[i] );
free ( node->hyperalert->postconds );
free ( node->hyperalert );
node->hyperalert = NULL;
}
if ( node->parent_alerts )
free ( node->parent_alerts );
if ( node->derived_alerts )
free ( node->derived_alerts );
free ( node );
node = NULL;
} /* ----- end of function AI_free_alerts ----- */
/** @} */
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