snort: rename snort-config to packet-snort-config

I sometimes type too fast and 'epan/dissectors/s<TAB>' ends up into
'epan/dissectors/snort-config.' which is never intentional.

Change-Id: I5bae7b303bbcc7057f15d5acfa9fa01610cd90ce
Reviewed-on: https://code.wireshark.org/review/34926
Petri-Dish: Peter Wu <peter@lekensteyn.nl>
Reviewed-by: Alexis La Goutte <alexis.lagoutte@gmail.com>
Tested-by: Petri Dish Buildbot
Reviewed-by: Anders Broman <a.broman58@gmail.com>

1 files changed, 1208 insertions, 0 deletions

diff --git a/epan/dissectors/packet-snort-config.c b/epan/dissectors/packet-snort-config.c
new file mode 100644
index 0000000000..2afe8e0b99
--- /dev/null
+++ b/epan/dissectors/packet-snort-config.c
@@ -0,0 +1,1208 @@
+/* packet-snort-config.c
+ *
+ * Copyright 2016, Martin Mathieson
+ *
+ * Wireshark - Network traffic analyzer
+ * By Gerald Combs <gerald@wireshark.org>
+ * Copyright 1998 Gerald Combs
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "config.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <ctype.h>
+
+#include <wsutil/file_util.h>
+#include <wsutil/strtoi.h>
+#include <wsutil/report_message.h>
+
+#include "packet-snort-config.h"
+
+/* Forward declaration */
+static void parse_config_file(SnortConfig_t *snort_config, FILE *config_file_fd, const char *filename, const char *dirname, int recursion_level);
+
+/* Skip white space from 'source', return pointer to first non-whitespace char */
+static char *skipWhiteSpace(char *source, int *accumulated_offset)
+{
+    int offset = 0;
+
+    /* Skip any leading whitespace */
+    while (source[offset] != '\0' && source[offset] == ' ') {
+        offset++;
+    }
+
+    *accumulated_offset += offset;
+    return source + offset;
+}
+
+/* Read a token from source, stop when get to end of string or delimiter. */
+/* - source: input string
+ * - delimiter:  char to stop at
+ * - length: out param set to delimiter or end-of-string offset
+ * - accumulated_Length: out param that gets length added to it
+ * - copy: whether or an allocated string should be returned
+ * - returns: requested string.  Returns from static buffer when copy is FALSE */
+static char* read_token(char* source, char delimeter, int *length, int *accumulated_length, gboolean copy)
+{
+    static char static_buffer[1024];
+    int offset = 0;
+
+    char *source_proper = skipWhiteSpace(source, accumulated_length);
+
+    while (source_proper[offset] != '\0' && source_proper[offset] != delimeter) {
+        offset++;
+    }
+
+    *length = offset;
+    *accumulated_length += offset;
+    if (copy) {
+        /* Copy into new string */
+        char *new_string = g_strndup(source_proper, offset+1);
+        new_string[offset] = '\0';
+        return new_string;
+    }
+    else {
+        /* Return in static buffer */
+        memcpy(&static_buffer, source_proper, offset);
+        static_buffer[offset] = '\0';
+        return static_buffer;
+    }
+}
+
+/* Add a new content field to the rule */
+static gboolean rule_add_content(Rule_t *rule, const char *content_string, gboolean negated)
+{
+    if (rule->number_contents < MAX_CONTENT_ENTRIES) {
+        content_t *new_content = &(rule->contents[rule->number_contents++]);
+        new_content->str = g_strdup(content_string);
+        new_content->negation = negated;
+        rule->last_added_content = new_content;
+        return TRUE;
+    }
+    return FALSE;
+}
+
+/* Set the nocase property for a rule */
+static void rule_set_content_nocase(Rule_t *rule)
+{
+    if (rule->last_added_content) {
+        rule->last_added_content->nocase = TRUE;
+    }
+}
+
+/* Set the offset property of a content field */
+static void rule_set_content_offset(Rule_t *rule, gint value)
+{
+    if (rule->last_added_content) {
+        rule->last_added_content->offset = value;
+        rule->last_added_content->offset_set = TRUE;
+    }
+}
+
+/* Set the depth property of a content field */
+static void rule_set_content_depth(Rule_t *rule, guint value)
+{
+    if (rule->last_added_content) {
+        rule->last_added_content->depth = value;
+    }
+}
+
+/* Set the distance property of a content field */
+static void rule_set_content_distance(Rule_t *rule, gint value)
+{
+    if (rule->last_added_content) {
+        rule->last_added_content->distance = value;
+        rule->last_added_content->distance_set = TRUE;
+    }
+}
+
+/* Set the distance property of a content field */
+static void rule_set_content_within(Rule_t *rule, guint value)
+{
+    if (rule->last_added_content) {
+        /* Assuming won't be 0... */
+        rule->last_added_content->within = value;
+    }
+}
+
+/* Set the fastpattern property of a content field */
+static void rule_set_content_fast_pattern(Rule_t *rule)
+{
+    if (rule->last_added_content) {
+        rule->last_added_content->fastpattern = TRUE;
+    }
+}
+
+/* Set the rawbytes property of a content field */
+static void rule_set_content_rawbytes(Rule_t *rule)
+{
+    if (rule->last_added_content) {
+        rule->last_added_content->rawbytes = TRUE;
+    }
+}
+
+/* Set the http_method property of a content field */
+static void rule_set_content_http_method(Rule_t *rule)
+{
+    if (rule->last_added_content) {
+        rule->last_added_content->http_method = TRUE;
+    }
+}
+
+/* Set the http_client property of a content field */
+static void rule_set_content_http_client_body(Rule_t *rule)
+{
+    if (rule->last_added_content) {
+        rule->last_added_content->http_client_body = TRUE;
+    }
+}
+
+/* Set the http_cookie property of a content field */
+static void rule_set_content_http_cookie(Rule_t *rule)
+{
+    if (rule->last_added_content) {
+        rule->last_added_content->http_cookie = TRUE;
+    }
+}
+
+/* Set the http_UserAgent property of a content field */
+static void rule_set_content_http_user_agent(Rule_t *rule)
+{
+    if (rule->last_added_content) {
+        rule->last_added_content->http_user_agent = TRUE;
+    }
+}
+
+/* Add a uricontent field to the rule */
+static gboolean rule_add_uricontent(Rule_t *rule, const char *uricontent_string, gboolean negated)
+{
+    if (rule_add_content(rule, uricontent_string, negated)) {
+        rule->last_added_content->content_type = UriContent;
+        return TRUE;
+    }
+    return FALSE;
+}
+
+/* This content field now becomes a uricontent after seeing modifier  */
+static void rule_set_http_uri(Rule_t *rule)
+{
+    if (rule->last_added_content != NULL) {
+        rule->last_added_content->content_type = UriContent;
+    }
+}
+
+/* Add a pcre field to the rule */
+static gboolean rule_add_pcre(Rule_t *rule, const char *pcre_string)
+{
+    if (rule_add_content(rule, pcre_string, FALSE)) {
+        rule->last_added_content->content_type = Pcre;
+        return TRUE;
+    }
+    return FALSE;
+}
+
+/* Set the rule's classtype field */
+static gboolean rule_set_classtype(Rule_t *rule, const char *classtype)
+{
+    rule->classtype = g_strdup(classtype);
+    return TRUE;
+}
+
+/* Add a reference string to the rule */
+static void rule_add_reference(Rule_t *rule, const char *reference_string)
+{
+    if (rule->number_references < MAX_REFERENCE_ENTRIES) {
+        rule->references[rule->number_references++] = g_strdup(reference_string);
+    }
+}
+
+/* Check to see if the ip 'field' corresponds to an entry in the ipvar dictionary.
+ * If it is add entry to rule */
+static void rule_check_ip_vars(SnortConfig_t *snort_config, Rule_t *rule, char *field)
+{
+    gpointer original_key = NULL;
+    gpointer value = NULL;
+
+    /* Make sure field+1 not NULL. */
+    if (strlen(field) < 2) {
+        return;
+    }
+
+    /* Make sure there is room for another entry */
+    if (rule->relevant_vars.num_ip_vars >= MAX_RULE_IP_VARS) {
+        return;
+    }
+
+    /* TODO: a loop re-looking up the answer until its not just another ipvar! */
+    if (g_hash_table_lookup_extended(snort_config->ipvars, field+1, &original_key, &value)) {
+
+        rule->relevant_vars.ip_vars[rule->relevant_vars.num_ip_vars].name = (char*)original_key;
+        rule->relevant_vars.ip_vars[rule->relevant_vars.num_ip_vars].value = (char*)value;
+
+        rule->relevant_vars.num_ip_vars++;
+    }
+}
+
+/* Check to see if the port 'field' corresponds to an entry in the portvar dictionary.
+ * If it is add entry to rule */
+static void rule_check_port_vars(SnortConfig_t *snort_config, Rule_t *rule, char *field)
+{
+    gpointer original_key = NULL;
+    gpointer value = NULL;
+
+    /* Make sure field+1 not NULL. */
+    if (strlen(field) < 2) {
+        return;
+    }
+
+    /* Make sure there is room for another entry */
+    if (rule->relevant_vars.num_port_vars >= MAX_RULE_PORT_VARS) {
+        return;
+    }
+
+    /* TODO: a loop re-looking up the answer until its not just another portvar! */
+    if (g_hash_table_lookup_extended(snort_config->portvars, field+1, &original_key, &value)) {
+        rule->relevant_vars.port_vars[rule->relevant_vars.num_port_vars].name = (char*)original_key;
+        rule->relevant_vars.port_vars[rule->relevant_vars.num_port_vars].value = (char*)value;
+
+        rule->relevant_vars.num_port_vars++;
+    }
+}
+
+/* Look over the IP addresses and ports, and work out which variables/values are being used */
+void rule_set_relevant_vars(SnortConfig_t *snort_config, Rule_t *rule)
+{
+    int length;
+    int accumulated_length = 0;
+    char *field;
+
+    /* No need to do this twice */
+    if (rule->relevant_vars.relevant_vars_set) {
+        return;
+    }
+
+    /* Walk tokens up to the options, and look up ones that are addresses or ports. */
+
+    /* Skip "alert" */
+    read_token(rule->rule_string+accumulated_length, ' ', &length, &accumulated_length, FALSE);
+
+    /* Skip protocol. */
+    read_token(rule->rule_string+accumulated_length, ' ', &length, &accumulated_length, FALSE);
+
+    /* Read source address */
+    field = read_token(rule->rule_string+accumulated_length, ' ', &length, &accumulated_length, FALSE);
+    rule_check_ip_vars(snort_config, rule, field);
+
+    /* Read source port */
+    field = read_token(rule->rule_string+accumulated_length, ' ', &length, &accumulated_length, FALSE);
+    rule_check_port_vars(snort_config, rule, field);
+
+    /* Read direction */
+    read_token(rule->rule_string+accumulated_length, ' ', &length, &accumulated_length, FALSE);
+
+    /* Dest address */
+    field = read_token(rule->rule_string+accumulated_length, ' ', &length, &accumulated_length, FALSE);
+    rule_check_ip_vars(snort_config, rule, field);
+
+    /* Dest port */
+    field = read_token(rule->rule_string+accumulated_length, ' ', &length, &accumulated_length, FALSE);
+    rule_check_port_vars(snort_config, rule, field);
+
+    /* Set flag so won't do again for this rule */
+    rule->relevant_vars.relevant_vars_set = TRUE;
+}
+
+
+typedef enum vartype_e { var, ipvar, portvar, unknownvar } vartype_e;
+
+/* Look for a "var", "ipvar" or "portvar" entry in this line */
+static gboolean parse_variables_line(SnortConfig_t *snort_config, char *line)
+{
+    vartype_e var_type = unknownvar;
+
+    char *  variable_type;
+    char *  variable_name;
+    char *  value;
+
+    int length;
+    int accumulated_length = 0;
+
+    /* Get variable type */
+    variable_type = read_token(line, ' ', &length, &accumulated_length, FALSE);
+    if (variable_type == NULL) {
+        return FALSE;
+    }
+
+    if (strncmp(variable_type, "var", 3) == 0) {
+        var_type = var;
+    }
+    else if (strncmp(variable_type, "ipvar", 5) == 0) {
+        var_type = ipvar;
+    }
+    else if (strncmp(variable_type, "portvar", 7) == 0) {
+        var_type = portvar;
+    }
+    else {
+        return FALSE;
+    }
+
+    /* Get variable name */
+    variable_name = read_token(line+ accumulated_length, ' ', &length, &accumulated_length, TRUE);
+    if (variable_name == NULL) {
+        return FALSE;
+    }
+
+    /* Now value */
+    value = read_token(line + accumulated_length, ' ', &length, &accumulated_length, TRUE);
+    if (value == NULL) {
+        return FALSE;
+    }
+
+    /* Add (name->value) to table according to variable type. */
+    switch (var_type) {
+        case var:
+            if (strcmp(variable_name, "RULE_PATH") == 0) {
+                /* This can be relative or absolute. */
+                snort_config->rule_path = value;
+                snort_config->rule_path_is_absolute = g_path_is_absolute(value);
+                snort_debug_printf("rule_path set to %s (is_absolute=%d)\n",
+                                   snort_config->rule_path, snort_config->rule_path_is_absolute);
+            }
+            g_hash_table_insert(snort_config->vars, variable_name, value);
+            break;
+        case ipvar:
+            g_hash_table_insert(snort_config->ipvars, variable_name, value);
+            break;
+        case portvar:
+            g_hash_table_insert(snort_config->portvars, variable_name, value);
+            break;
+
+        default:
+            return FALSE;
+    }
+
+    return FALSE;
+}
+
+/* Hash function for where key is a string. Just add up the value of each character and return that.. */
+static guint string_hash(gconstpointer key)
+{
+    guint total=0, n=0;
+    const char *key_string = (const char *)key;
+    char c = key_string[n];
+
+    while (c != '\0') {
+        total += (int)c;
+        c = key_string[++n];
+    }
+    return total;
+}
+
+/* Comparison function for where key is a string. Simple comparison using strcmp() */
+static gboolean string_equal(gconstpointer a, gconstpointer b)
+{
+    const char *stringa = (const char*)a;
+    const char *stringb = (const char*)b;
+
+    return (strcmp(stringa, stringb) == 0);
+}
+
+/* Process a line that configures a reference line (invariably from 'reference.config') */
+static gboolean parse_references_prefix_file_line(SnortConfig_t *snort_config, char *line)
+{
+    char *source;
+    char *prefix_name, *prefix_value;
+    int length=0, accumulated_length=0;
+    int n;
+
+    if (strncmp(line, "config reference: ", 18) != 0) {
+        return FALSE;
+    }
+
+    /* Read the prefix and value */
+    source = line+18;
+    prefix_name = read_token(source, ' ', &length, &accumulated_length, TRUE);
+    /* Store all name chars in lower case. */
+    for (n=0; prefix_name[n] != '\0'; n++) {
+        prefix_name[n] = g_ascii_tolower(prefix_name[n]);
+    }
+
+    prefix_value = read_token(source+accumulated_length, ' ', &length, &accumulated_length, TRUE);
+
+    /* Add entry into table */
+    g_hash_table_insert(snort_config->references_prefixes, prefix_name, prefix_value);
+
+    return FALSE;
+}
+
+/* Try to expand the reference using the prefixes stored in the config */
+char *expand_reference(SnortConfig_t *snort_config, char *reference)
+{
+    static char expanded_reference[512];
+    int length = (int)strlen(reference);
+    int accumulated_length = 0;
+
+    /* Extract up to ',', then substitute prefix! */
+    snort_debug_printf("expand_reference(%s)\n", reference);
+    char *prefix = read_token(reference, ',', &length, &accumulated_length, FALSE);
+
+    if (*prefix != '\0') {
+        /* Convert to lowercase before lookup */
+        guint n;
+        for (n=0; prefix[n] != '\0'; n++) {
+            prefix[n] = g_ascii_tolower(prefix[n]);
+        }
+
+        /* Look up prefix in table. */
+        char *prefix_replacement;
+        prefix_replacement = (char*)g_hash_table_lookup(snort_config->references_prefixes, prefix);
+
+        /* Append prefix and remainder, and return!!!! */
+        g_snprintf(expanded_reference, 512, "%s%s", prefix_replacement, reference+length+1);
+        return expanded_reference;
+    }
+    return "ERROR: Reference didn't contain prefix and ','!";
+}
+
+/* The rule has been matched with an alert, so update global config stats */
+void rule_set_alert(SnortConfig_t *snort_config, Rule_t *rule,
+                    guint *global_match_number,
+                    guint *rule_match_number)
+{
+    snort_config->stat_alerts_detected++;
+    *global_match_number = snort_config->stat_alerts_detected;
+    if (rule != NULL) {
+        *rule_match_number = ++rule->matches_seen;
+    }
+}
+
+
+
+/* Delete an individual entry from a string table. */
+static gboolean delete_string_entry(gpointer key,
+                                    gpointer value,
+                                    gpointer user_data _U_)
+{
+    char *key_string = (char*)key;
+    char *value_string = (char*)value;
+
+    g_free(key_string);
+    g_free(value_string);
+
+    return TRUE;
+}
+
+/* See if this is an include line, if it is open the file and call parse_config_file() */
+static gboolean parse_include_file(SnortConfig_t *snort_config, char *line, const char *config_directory, int recursion_level)
+{
+    int length;
+    int accumulated_length = 0;
+    char *include_filename;
+
+    /* Look for "include " */
+    char *include_token = read_token(line, ' ', &length, &accumulated_length, FALSE);
+    if (strlen(include_token) == 0) {
+        return FALSE;
+    }
+    if (strncmp(include_token, "include", 7) != 0) {
+        return FALSE;
+    }
+
+    /* Read the filename */
+    include_filename = read_token(line+accumulated_length, ' ', &length, &accumulated_length, FALSE);
+    if (*include_filename != '\0') {
+        FILE *new_config_fd;
+        char *substituted_filename;
+        gboolean is_rule_file = FALSE;
+
+        /* May need to substitute variables into include path. */
+        if (strncmp(include_filename, "$RULE_PATH", 10) == 0) {
+            /* Write rule path variable value */
+            /* Don't assume $RULE_PATH will end in a file separator */
+            if (snort_config->rule_path_is_absolute) {
+                /* Rule path is absolute, so it can go at start */
+                substituted_filename = g_build_path(G_DIR_SEPARATOR_S,
+                           snort_config->rule_path,
+                           include_filename + 11,
+                           NULL);
+            }
+            else {
+                /* Rule path is relative to config directory, so it goes first */
+                substituted_filename = g_build_path(G_DIR_SEPARATOR_S,
+                           config_directory,
+                           snort_config->rule_path,
+                           include_filename + 11,
+                           NULL);
+            }
+            is_rule_file = TRUE;
+        }
+        else {
+            /* No $RULE_PATH, just use directory and filename */
+            /* But may not even need directory if included_folder is absolute! */
+            if (!g_path_is_absolute(include_filename)) {
+                substituted_filename = g_build_path(G_DIR_SEPARATOR_S,
+                            config_directory, include_filename, NULL);
+            }
+            else {
+                substituted_filename = g_strdup(include_filename);
+            }
+        }
+
+        /* Try to open the file. */
+        new_config_fd = ws_fopen(substituted_filename, "r");
+        if (new_config_fd == NULL) {
+            snort_debug_printf("Failed to open config file %s\n", substituted_filename);
+            report_failure("Snort dissector: Failed to open config file %s\n", substituted_filename);
+            g_free(substituted_filename);
+            return FALSE;
+        }
+
+        /* Parse the file */
+        if (is_rule_file) {
+            snort_config->stat_rules_files++;
+        }
+        parse_config_file(snort_config, new_config_fd, substituted_filename, config_directory, recursion_level + 1);
+        g_free(substituted_filename);
+
+        /* Close the file */
+        fclose(new_config_fd);
+
+        return TRUE;
+    }
+    return FALSE;
+}
+
+/* Process an individual option - i.e. the elements found between '(' and ')' */
+static void process_rule_option(Rule_t *rule, char *options, int option_start_offset, int options_end_offset, int colon_offset)
+{
+    static char name[1024], value[1024];
+    name[0] = '\0';
+    value[0] = '\0';
+    gint value_length = 0;
+    guint32 value32 = 0;
+    gint spaces_after_colon = 0;
+
+    if (colon_offset != 0) {
+        /* Name and value */
+        g_strlcpy(name, options+option_start_offset, colon_offset-option_start_offset);
+        if (options[colon_offset] == ' ') {
+            spaces_after_colon = 1;
+        }
+        g_strlcpy(value, options+colon_offset+spaces_after_colon, options_end_offset-spaces_after_colon-colon_offset);
+        value_length = (gint)strlen(value);
+    }
+    else {
+        /* Just name */
+        g_strlcpy(name, options+option_start_offset, options_end_offset-option_start_offset);
+    }
+
+    /* Some rule options expect a number, parse it now. Note that any space
+     * after the value will currently result in the number being ignored. */
+    ws_strtoi32(value, NULL, &value32);
+
+    /* Think this is space at end of all options - don't compare with option names */
+    if (name[0] == '\0') {
+        return;
+    }
+
+    /* Process the rule options that we are interested in */
+    if (strcmp(name, "msg") == 0) {
+        rule->msg = g_strdup(value);
+    }
+    else if (strcmp(name, "sid") == 0) {
+        rule->sid = value32;
+    }
+    else if (strcmp(name, "rev") == 0) {
+        rule->rev = value32;
+    }
+    else if (strcmp(name, "content") == 0) {
+        int value_start = 0;
+
+        if (value_length < 3) {
+            return;
+        }
+
+        /* Need to trim off " ", but first check for ! */
+        if (value[0] == '!') {
+            value_start = 1;
+            if (value_length < 4) {
+                /* i.e. also need quotes + at least one character */
+                return;
+            }
+        }
+
+        value[options_end_offset-colon_offset-spaces_after_colon-2] = '\0';
+        rule_add_content(rule, value+value_start+1, value_start == 1);
+    }
+    else if (strcmp(name, "uricontent") == 0) {
+        int value_start = 0;
+
+        if (value_length < 3) {
+            return;
+        }
+
+        /* Need to trim off " ", but first check for ! */
+        if (value[0] == '!') {
+            value_start = 1;
+            if (value_length < 4) {
+                return;
+            }
+        }
+
+        value[options_end_offset-colon_offset-spaces_after_colon-2] = '\0';
+        rule_add_uricontent(rule, value+value_start+1, value_start == 1);
+    }
+    else if (strcmp(name, "http_uri") == 0) {
+        rule_set_http_uri(rule);
+    }
+    else if (strcmp(name, "pcre") == 0) {
+        int value_start = 0;
+
+        /* Need at least opening and closing / */
+        if (value_length < 3) {
+            return;
+        }
+
+        /* Not expecting negation (!)... */
+
+        value[options_end_offset-colon_offset-spaces_after_colon-2] = '\0';
+        rule_add_pcre(rule, value+value_start+1);
+    }
+    else if (strcmp(name, "nocase") == 0) {
+        rule_set_content_nocase(rule);
+    }
+    else if (strcmp(name, "offset") == 0) {
+        rule_set_content_offset(rule, value32);
+    }
+    else if (strcmp(name, "depth") == 0) {
+        rule_set_content_depth(rule, value32);
+    }
+    else if (strcmp(name, "within") == 0) {
+        rule_set_content_within(rule, value32);
+    }
+    else if (strcmp(name, "distance") == 0) {
+        rule_set_content_distance(rule, value32);
+    }
+    else if (strcmp(name, "fast_pattern") == 0) {
+        rule_set_content_fast_pattern(rule);
+    }
+    else if (strcmp(name, "http_method") == 0) {
+        rule_set_content_http_method(rule);
+    }
+    else if (strcmp(name, "http_client_body") == 0) {
+        rule_set_content_http_client_body(rule);
+    }
+    else if (strcmp(name, "http_cookie") == 0) {
+        rule_set_content_http_cookie(rule);
+    }
+    else if (strcmp(name, "http_user_agent") == 0) {
+        rule_set_content_http_user_agent(rule);
+    }
+    else if (strcmp(name, "rawbytes") == 0) {
+        rule_set_content_rawbytes(rule);
+    }
+    else if (strcmp(name, "classtype") == 0) {
+        rule_set_classtype(rule, value);
+    }
+    else if (strcmp(name, "reference") == 0) {
+        rule_add_reference(rule, value);
+    }
+    else {
+        /* Ignore an option we don't currently handle */
+    }
+}
+
+/* Parse a Snort alert, return TRUE if successful */
+static gboolean parse_rule(SnortConfig_t *snort_config, char *line, const char *filename, int line_number, int line_length)
+{
+    char *options_start;
+    char *options;
+    gboolean in_quotes = FALSE;
+    int options_start_index = 0, options_index = 0, colon_offset = 0;
+    char c;
+    int length = 0; /*  CID 1398227 (bogus - read_token() always sets it) */
+    Rule_t *rule = NULL;
+
+    /* Rule will begin with alert */
+    if (strncmp(line, "alert ", 6) != 0) {
+        return FALSE;
+    }
+
+    /* Allocate the rule itself */
+    rule = (Rule_t*)g_malloc(sizeof(Rule_t));
+
+    snort_debug_printf("looks like a rule: %s\n", line);
+    memset(rule, 0, sizeof(Rule_t));
+
+    rule->rule_string = g_strdup(line);
+    rule->file = g_strdup(filename);
+    rule->line_number = line_number;
+
+    /* Next token is the protocol */
+    rule->protocol = read_token(line+6, ' ', &length, &length, TRUE);
+
+    /* Find start of options. */
+    options_start = strstr(line, "(");
+    if (options_start == NULL) {
+        snort_debug_printf("start of options not found\n");
+        g_free(rule);
+        return FALSE;
+    }
+    options_index = (int)(options_start-line) + 1;
+
+    /* To make parsing simpler, replace final ')' with ';' */
+    if (line[line_length-1] != ')') {
+        g_free(rule);
+        return FALSE;
+    }
+    else {
+        line[line_length-1] = ';';
+    }
+
+    /* Skip any spaces before next option */
+    while (line[options_index] == ' ') options_index++;
+
+    /* Now look for next ';', process one option at a time */
+    options = &line[options_index];
+    options_index = 0;
+
+    while ((c = options[options_index++])) {
+        /* Keep track of whether inside quotes */
+        if (c == '"') {
+            in_quotes = !in_quotes;
+        }
+        /* Ignore ';' while inside quotes */
+        if (!in_quotes) {
+            if (c == ':') {
+                colon_offset = options_index;
+            }
+            if (c == ';') {
+                /* End of current option - add to rule. */
+                process_rule_option(rule, options, options_start_index, options_index, colon_offset);
+
+                /* Skip any spaces before next option */
+                while (options[options_index] == ' ') options_index++;
+
+                /* Next rule will start here */
+                options_start_index = options_index;
+                colon_offset = 0;
+                in_quotes = FALSE;
+            }
+        }
+    }
+
+    /* Add rule to map of rules. */
+    g_hash_table_insert(snort_config->rules, GUINT_TO_POINTER((guint)rule->sid), rule);
+    snort_debug_printf("Snort rule with SID=%u added to table\n", rule->sid);
+
+    return TRUE;
+}
+
+/* Delete an individual rule */
+static gboolean delete_rule(gpointer  key _U_,
+                            gpointer  value,
+                            gpointer  user_data _U_)
+{
+    Rule_t *rule = (Rule_t*)value;
+    unsigned int n;
+
+    /* Delete strings on heap. */
+    g_free(rule->rule_string);
+    g_free(rule->file);
+    g_free(rule->msg);
+    g_free(rule->classtype);
+    g_free(rule->protocol);
+
+    for (n=0; n < rule->number_contents; n++) {
+        g_free(rule->contents[n].str);
+        g_free(rule->contents[n].translated_str);
+    }
+
+    for (n=0; n < rule->number_references; n++) {
+        g_free(rule->references[n]);
+    }
+
+    snort_debug_printf("Freeing rule at :%p\n", rule);
+    g_free(rule);
+    return TRUE;
+}
+
+
+/* Parse this file, adding details to snort_config. */
+/* N.B. using recursion_level to limit stack depth. */
+#define MAX_CONFIG_FILE_RECURSE_DEPTH 8
+static void parse_config_file(SnortConfig_t *snort_config, FILE *config_file_fd,
+                              const char *filename, const char *dirname, int recursion_level)
+{
+    #define MAX_LINE_LENGTH 4096
+    char line[MAX_LINE_LENGTH];
+    int  line_number = 0;
+
+    snort_debug_printf("parse_config_file(filename=%s, recursion_level=%d)\n", filename, recursion_level);
+
+    if (recursion_level > MAX_CONFIG_FILE_RECURSE_DEPTH) {
+        return;
+    }
+
+    /* Read each line of the file in turn, and see if we want any info from it. */
+    while (fgets(line, MAX_LINE_LENGTH, config_file_fd)) {
+
+        int line_length;
+        ++line_number;
+
+        /* Nothing interesting to parse */
+        if ((line[0] == '\0') || (line[0] == '#')) {
+            continue;
+        }
+
+        /* Trim newline from end */
+        line_length = (int)strlen(line);
+        while (line_length && ((line[line_length - 1] == '\n') || (line[line_length - 1] == '\r'))) {
+            --line_length;
+        }
+        line[line_length] = '\0';
+        if (line_length == 0) {
+            continue;
+        }
+
+        /* Offer line to the various parsing functions.  Could optimise order.. */
+        if (parse_variables_line(snort_config, line)) {
+            continue;
+        }
+        if (parse_references_prefix_file_line(snort_config, line)) {
+            continue;
+        }
+        if (parse_include_file(snort_config, line, dirname, recursion_level)) {
+            continue;
+        }
+        if (parse_rule(snort_config, line, filename, line_number, line_length)) {
+            snort_config->stat_rules++;
+            continue;
+        }
+    }
+}
+
+
+
+/* Create the global ConfigParser */
+void create_config(SnortConfig_t **snort_config, const char *snort_config_file)
+{
+    gchar* dirname;
+    gchar* basename;
+    FILE *config_file_fd;
+
+    snort_debug_printf("create_config (%s)\n", snort_config_file);
+
+    *snort_config = (SnortConfig_t*)g_malloc(sizeof(SnortConfig_t));
+    memset(*snort_config, 0, sizeof(SnortConfig_t));
+
+    /* Create rule table */
+    (*snort_config)->rules = g_hash_table_new(g_direct_hash, g_direct_equal);
+
+    /* Create reference prefix table */
+    (*snort_config)->references_prefixes = g_hash_table_new(string_hash, string_equal);
+
+    /* Vars tables */
+    (*snort_config)->vars = g_hash_table_new(string_hash, string_equal);
+    (*snort_config)->ipvars = g_hash_table_new(string_hash, string_equal);
+    (*snort_config)->portvars = g_hash_table_new(string_hash, string_equal);
+
+    /* Extract separate directory and filename. */
+    dirname =  g_path_get_dirname(snort_config_file);
+    basename =  g_path_get_basename(snort_config_file);
+
+    /* Attempt to open the config file */
+    config_file_fd = ws_fopen(snort_config_file, "r");
+    if (config_file_fd == NULL) {
+        snort_debug_printf("Failed to open config file %s\n", snort_config_file);
+        report_failure("Snort dissector: Failed to open config file %s\n", snort_config_file);
+        return;
+    }
+
+    /* Start parsing from the top-level config file. */
+    parse_config_file(*snort_config, config_file_fd, snort_config_file, dirname, 1 /* recursion level */);
+
+    g_free(dirname);
+    g_free(basename);
+
+    fclose(config_file_fd);
+}
+
+
+/* Delete the entire config */
+void delete_config(SnortConfig_t **snort_config)
+{
+    snort_debug_printf("delete_config()\n");
+
+    /* Iterate over all rules, freeing each one! */
+    g_hash_table_foreach_remove((*snort_config)->rules, delete_rule, NULL);
+    g_hash_table_destroy((*snort_config)->rules);
+
+    /* References table */
+    g_hash_table_foreach_remove((*snort_config)->references_prefixes, delete_string_entry, NULL);
+    g_hash_table_destroy((*snort_config)->references_prefixes);
+
+    /* Free up variable tables */
+    g_hash_table_foreach_remove((*snort_config)->vars, delete_string_entry, NULL);
+    g_hash_table_destroy((*snort_config)->vars);
+    g_hash_table_foreach_remove((*snort_config)->ipvars, delete_string_entry, NULL);
+    g_hash_table_destroy((*snort_config)->ipvars);
+    g_hash_table_foreach_remove((*snort_config)->portvars, delete_string_entry, NULL);
+    g_hash_table_destroy((*snort_config)->portvars);
+
+    g_free(*snort_config);
+
+    *snort_config = NULL;
+}
+
+/* Look for a rule corresponding to the given SID */
+Rule_t *get_rule(SnortConfig_t *snort_config, guint32 sid)
+{
+    if ((snort_config == NULL) || (snort_config->rules == NULL)) {
+        return NULL;
+    }
+    else {
+        return (Rule_t*)g_hash_table_lookup(snort_config->rules, GUINT_TO_POINTER(sid));
+    }
+}
+
+/* Fetch some statistics. */
+void get_global_rule_stats(SnortConfig_t *snort_config, unsigned int sid,
+                           unsigned int *number_rules_files, unsigned int *number_rules,
+                           unsigned int *alerts_detected, unsigned int *this_rule_alerts_detected)
+{
+    *number_rules_files = snort_config->stat_rules_files;
+    *number_rules = snort_config->stat_rules;
+    *alerts_detected = snort_config->stat_alerts_detected;
+    Rule_t *rule;
+
+    /* Look up rule and get current/total matches */
+    rule = get_rule(snort_config, sid);
+    if (rule) {
+        *this_rule_alerts_detected = rule->matches_seen;
+    }
+    else {
+        *this_rule_alerts_detected = 0;
+    }
+}
+
+/* Reset stats on individual rule */
+static void reset_rule_stats(gpointer  key _U_,
+                             gpointer  value,
+                             gpointer  user_data _U_)
+{
+    Rule_t *rule = (Rule_t*)value;
+    rule->matches_seen = 0;
+}
+
+/* Reset stats on all rules */
+void reset_global_rule_stats(SnortConfig_t *snort_config)
+{
+    /* Reset global stats */
+    if (snort_config == NULL) {
+        return;
+    }
+    snort_config->stat_alerts_detected = 0;
+
+    /* Iterate over all rules, resetting the stats of each */
+    g_hash_table_foreach(snort_config->rules, reset_rule_stats, NULL);
+}
+
+
+/*************************************************************************************/
+/* Dealing with content fields and trying to find where it matches within the packet */
+/* Parse content strings to interpret binary and escaped characters. Do this         */
+/* so we can look for in frame using memcmp().                                       */
+static unsigned char content_get_nibble_value(char c)
+{
+    static unsigned char values[256];
+    static gboolean values_set = FALSE;
+
+    if (!values_set) {
+        /* Set table once and for all */
+        unsigned char ch;
+        for (ch='a'; ch <= 'f'; ch++) {
+            values[ch] = 0xa + (ch-'a');
+        }
+        for (ch='A'; ch <= 'F'; ch++) {
+            values[ch] = 0xa + (ch-'A');
+        }
+        for (ch='0'; ch <= '9'; ch++) {
+            values[ch] = (ch-'0');
+        }
+        values_set = TRUE;
+    }
+
+    return values[(unsigned char)c];
+}
+
+/* Go through string, converting hex digits into guint8, and removing escape characters. */
+guint content_convert_to_binary(content_t *content)
+{
+    int output_idx = 0;
+    gboolean in_binary_mode = FALSE;    /* Are we in a binary region of the string?   */
+    gboolean have_one_nibble = FALSE;   /* Do we have the first nibble of the pair needed to make a byte? */
+    unsigned char one_nibble = 0;       /* Value of first nibble if we have it */
+    char c;
+    int n;
+    gboolean have_backslash = FALSE;
+    static gchar binary_str[1024];
+
+    /* Just return length if have previously translated in binary string. */
+    if (content->translated) {
+        return content->translated_length;
+    }
+
+    /* Walk over each character, work out what needs to be written into output */
+    for (n=0; content->str[n] != '\0'; n++) {
+        c = content->str[n];
+        if (c == '|') {
+            /* Flip binary mode */
+            in_binary_mode = !in_binary_mode;
+            continue;
+        }
+
+        if (!in_binary_mode) {
+            /* Not binary mode. Copying characters into output buffer, but watching out for escaped chars. */
+            if (!have_backslash) {
+                if (c == '\\') {
+                    /* Just note that we have a backslash */
+                    have_backslash = TRUE;
+                    continue;
+                }
+                else {
+                    /* Just copy the character straight into output. */
+                    binary_str[output_idx++] = (unsigned char)c;
+                }
+            }
+            else {
+                /* Currently have a backslash. Reset flag. */
+                have_backslash = 0;
+                /* Just copy the character into output. Really, the only characters that should be escaped
+                   are ';' and  '\'  and '"' */
+                binary_str[output_idx++] = (unsigned char)c;
+            }
+        }
+        else {
+            /* Binary mode. Handle pairs of hex digits and translate into guint8 */
+            if (c == ' ') {
+                /* Ignoring inside binary mode */
+                continue;
+            }
+            else {
+                unsigned char nibble = content_get_nibble_value(c);
+                if (!have_one_nibble) {
+                    /* Store first nibble of a pair */
+                    one_nibble = nibble;
+                    have_one_nibble = TRUE;
+                }
+                else {
+                    /* Combine both nibbles into a byte */
+                    binary_str[output_idx++] = (one_nibble << 4) + nibble;
+                    /* Reset flag - looking for new pair of nibbles */
+                    have_one_nibble = FALSE;
+                }
+            }
+        }
+    }
+
+    /* Store result for next time. */
+    content->translated_str = (guchar*)g_malloc(output_idx+1);
+    memcpy(content->translated_str, binary_str, output_idx+1);
+    content->translated = TRUE;
+    content->translated_length = output_idx;
+
+    return output_idx;
+}
+
+/* In order to use glib's regex library, need to trim
+  '/' delimiters and any modifiers from the end of the string */
+gboolean content_convert_pcre_for_regex(content_t *content)
+{
+    guint pcre_length, i, end_delimiter_offset = 0;
+
+    /* Return if already converted */
+    if (content->translated_str) {
+        return TRUE;
+    }
+
+    pcre_length = (guint)strlen(content->str);
+
+    /* Start with content->str */
+    if (pcre_length < 3) {
+        /* Can't be valid.  Expect /regex/[modifiers] */
+        return FALSE;
+    }
+
+    if (pcre_length >= 512) {
+        /* Have seen regex library crash on very long expressions
+         * (830 bytes) as seen in SID=2019326, REV=6 */
+        return FALSE;
+    }
+
+    /* Verify that string starts with / */
+    if (content->str[0] != '/') {
+        return FALSE;
+    }
+
+    /* Next, look for closing / near end of string */
+    for (i=pcre_length-1; i > 2; i--) {
+        if (content->str[i] == '/') {
+            end_delimiter_offset = i;
+            break;
+        }
+        else {
+            switch (content->str[i]) {
+                case 'i':
+                    content->pcre_case_insensitive = TRUE;
+                    break;
+                case 's':
+                    content->pcre_dot_includes_newline = TRUE;
+                    break;
+                case 'B':
+                    content->pcre_raw = TRUE;
+                    break;
+                case 'm':
+                    content->pcre_multiline = TRUE;
+                    break;
+
+                default:
+                    /* TODO: handle other modifiers that will get seen? */
+                    /* N.B. 'U' (match in decoded URI buffers) can't be handled, so don't store in flag. */
+                    /* N.B. not sure if/how to handle 'R' (effectively distance:0) */
+                    snort_debug_printf("Unhandled pcre modifier '%c'\n", content->str[i]);
+                    break;
+            }
+        }
+    }
+    if (end_delimiter_offset == 0) {
+        /* Didn't find it */
+        return FALSE;
+    }
+
+    /* Store result for next time. */
+    content->translated_str = (guchar*)g_malloc(end_delimiter_offset);
+    memcpy(content->translated_str, content->str+1, end_delimiter_offset - 1);
+    content->translated_str[end_delimiter_offset-1] = '\0';
+    content->translated = TRUE;
+    content->translated_length = end_delimiter_offset - 1;
+
+    return TRUE;
+}
+
+/*
+ * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
+ *
+ * Local variables:
+ * c-basic-offset: 4
+ * tab-width: 8
+ * indent-tabs-mode: nil
+ * End:
+ *
+ * vi: set shiftwidth=4 tabstop=8 expandtab:
+ * :indentSize=4:tabSize=8:noTabs=true:
+ */