Optimization on the status engine call

The status string was too long. By removing meaningless stuff, such as: runtime
version of Lua, we have reduced the length of the status string. Limitations
were also placed regarding the size of the ModSecurity version. Big queries may
lead to failure, due to restrictions of "gethostbyname". There is also a bit of
code cosmetics in this patch: big functions were broken into smaller.

Author: Felipe Zimmerle

Diff for: apache2/msc_status_engine.c

@@ -29,8 +29,8 @@
 #include <sys/utsname.h>
 #include <sys/types.h>
 #include <sys/socket.h>
-#if ! defined(IFT_ETHER)
-#define IFT_ETHER 0x6/* Ethernet CSMACD */
+#ifndef IFT_ETHER
+#define IFT_ETHER 0x6 /* Ethernet CSMACD */
 #endif
 #endif
 
@@ -42,7 +42,7 @@
 
 // Bese32 encode, based on:
 // https://code.google.com/p/google-authenticator/source/browse/libpam/base32.c
-void DSOLOCAL msc_status_engine_base32_encode(char *encoded,
+int DSOLOCAL msc_status_engine_base32_encode(char *encoded,
     const char *data, int len) {
     int buffer;
     int count = 0;
@@ -51,6 +51,11 @@ void DSOLOCAL msc_status_engine_base32_encode(char *encoded,
 
     buffer = data[0];
 
+    if (encoded == NULL && len == 0) {
+        len = length * 3;
+        count++;
+    }
+
     if (length > 0) {
         int next = 1;
         int bitsLeft = 8;
@@ -69,27 +74,48 @@ void DSOLOCAL msc_status_engine_base32_encode(char *encoded,
             }
             index = 0x1f & (buffer >> (bitsLeft - 5));
             bitsLeft -= 5;
-            result[count++] = msc_status_engine_basis_32[index];
+            if (encoded != NULL) {
+                result[count] = msc_status_engine_basis_32[index];
+            }
+            count++;
         }
     }
-    if (count < len) {
+    if (count < len && encoded != NULL) {
         result[count] = '\000';
     }
+
+    return count;
 }
 
-void DSOLOCAL msc_status_engine_fill_with_dots(char *encoded_with_dots,
+int DSOLOCAL msc_status_engine_fill_with_dots(char *encoded_with_dots,
     const char *data, int len, int space)
 {
     int i;
     int count = 0;
 
+    if (encoded_with_dots == NULL) {
+        if (len == 0 && data != NULL) {
+            len = strlen(data);
+        }
+        else if (len == 0 && data == NULL) {
+            count = -1;
+            goto return_length;
+        }
+
+        count = len/space + len + 1;
+        goto return_length;
+    }
+
     for (i = 0; i < strlen(data) && i < len; i++) {
         if (i % space == 0 && i != 0) {
             encoded_with_dots[count++] = '.';
         }
         encoded_with_dots[count++] = data[i];
     }
     encoded_with_dots[count] = '\0';
+
+return_length:
+    return count;
 }
 
 
@@ -103,7 +129,9 @@ int DSOLOCAL msc_status_engine_machine_name(char *machine_name, size_t len) {
     memset(machine_name, '\0', sizeof(char) * len);
 
 #ifdef WIN32
-    GetComputerName(machine_name, &lenComputerName);
+    if (GetComputerName(machine_name, &lenComputerName) == 0) {
+        goto failed;
+    }
 #else
    static struct utsname u;
 
@@ -227,7 +255,6 @@ int DSOLOCAL msc_status_engine_mac_address (unsigned char *mac)
     free(pAdapterInfo);
 #endif
 
-done:
     return 0;
 
 failed:
@@ -296,137 +323,167 @@ int DSOLOCAL msc_status_engine_unique_id (unsigned char *digest)
     return ret;
 }
 
-int msc_status_engine_call (void) {
+int DSOLOCAL msc_beacon_string (char *beacon_string, int beacon_string_max_len) {
     char *apr = NULL;
     const char *apr_loaded = NULL;
     char pcre[7];
     const char *pcre_loaded = NULL;
     char *lua = NULL;
-    char *lua_loaded = NULL;
     char *libxml = NULL;
-    char *libxml_loaded = NULL;
     char *modsec = NULL;
     const char *apache = NULL;
-    char *id = NULL;
-    char *beacon_string = NULL;
-    int beacon_string_len = 0;
-    char *beacon_string_encoded = NULL;
-    char *beacon_string_ready = NULL;
-    char *beacon_string_encoded_splitted = NULL;
-    int ret = 0;
+    char id[(APR_SHA1_DIGESTSIZE*2) + 1];
+    int beacon_string_len = -1;
 
     apr = APR_VERSION_STRING;
     apr_loaded = apr_version_string();
-
+    apr_snprintf(pcre, 7, "%d.%d", PCRE_MAJOR, PCRE_MINOR);
     pcre_loaded = pcre_version();
-    apr_snprintf(pcre, 7, "%2d.%2d ", PCRE_MAJOR, PCRE_MINOR);
 #ifdef WITH_LUA
     lua = LUA_VERSION;
 #endif
-    lua_loaded = 0;
-
     libxml = LIBXML_DOTTED_VERSION;
-    libxml_loaded = 0;
-
     modsec = MODSEC_VERSION;
+#ifdef WIN32
+    apache = "IIS";
+#else
     apache = apache_get_server_version();
+#endif
 
-    id = malloc(sizeof(char)*((2*APR_SHA1_DIGESTSIZE)+1));
-    if (!id) {
-        ret = -1;
-        goto failed_id;
+    /* 6 represents: strlen("(null)") */
+    beacon_string_len = (modsec ? strlen(modsec) : 6) +
+        (apache ? strlen(apache) : 6) + (apr ? strlen(apr) : 6) +
+        (apr_loaded ? strlen(apr_loaded) : 6) + (pcre ? strlen(pcre) : 6) +
+        (pcre_loaded ? strlen(pcre_loaded) : 6) + (lua ? strlen(lua) : 6) +
+        (libxml ? strlen(libxml) : 6) + (APR_SHA1_DIGESTSIZE * 2);
+
+    beacon_string_len = beacon_string_len + /* null terminator: */ 1 +
+            /* comma: */ 6 +
+            /* slash: */ 2;
+
+    if (beacon_string == NULL || beacon_string_max_len == 0) {
+        goto return_length;
     }
 
-    memset(id, '\0', sizeof(char)*((2*APR_SHA1_DIGESTSIZE)+1));
+    memset(id, '\0', sizeof(char)*((2 * APR_SHA1_DIGESTSIZE) + /* \0: */ 1));
     if (msc_status_engine_unique_id(id)) {
         sprintf(id, "unique id failed");
     }
 
-    beacon_string_len = (modsec ? strlen(modsec) : 6) + (apache ? strlen(apache) : 6) +
-        (apr ? strlen(apr) : 6) + (apr_loaded ? strlen(apr_loaded) : 6) +
-        (pcre ? strlen(pcre) : 6) + (pcre_loaded ? strlen(pcre_loaded) : 6) +
-        (lua ? strlen(lua) : 6) + (lua_loaded ? strlen(lua_loaded) : 6) +
-        (libxml ? strlen(libxml) : 6) + (libxml_loaded ? strlen(libxml_loaded) : 6) +
-        (id ? strlen(id) : 6);
+    apr_snprintf(beacon_string, beacon_string_max_len,
+        "%.25s,%s,%s/%s,%s/%s,%s,%s,%s",
+        modsec, apache, apr, apr_loaded, pcre, pcre_loaded, lua, libxml, id);
 
-#ifdef WIN32
-    beacon_string = malloc(sizeof(char)*(beacon_string_len+1+10+4));
-    if (!beacon_string) {
-        goto failed_beacon_string;
+return_length:
+    return beacon_string_len;
+}
+
+int DSOLOCAL msc_status_engine_prepare_hostname (char *hostname, const char *plain_data,
+        int max_length)
+{
+    int str_enc_len = 0;
+    int str_enc_spl_len = 0;
+    char *tmp = NULL;
+    int length = -1;
+
+    str_enc_len = msc_status_engine_base32_encode(NULL, plain_data, 0);
+
+    str_enc_spl_len = msc_status_engine_fill_with_dots(NULL, NULL, str_enc_len,
+            STATUS_ENGINE_DNS_IN_BETWEEN_DOTS);
+    if (str_enc_spl_len < 0) {
+        goto failed_enc_spl_len;
     }
 
-    apr_snprintf(beacon_string, beacon_string_len+1+10+4,
-        "%s,IIS,%s/%s,%s/%s,%s/%s,%s/%s,%s",
-        modsec, apr, apr_loaded, pcre, pcre_loaded, lua, lua_loaded,
-        libxml, libxml_loaded, id);
-#else
-    beacon_string = malloc(sizeof(char)*(beacon_string_len+1+10));
-    if (!beacon_string) {
-        goto failed_beacon_string;
+    length = str_enc_spl_len + strlen(STATUS_ENGINE_DNS_SUFFIX) +
+        /* epoch: */ 10 + /* dots: */ 2 + /* terminator: */ 1 -
+        /* removed unsed terminators from str_enc and str_enc_spl: */ 2;
+
+    if (hostname == NULL || max_length == 0) {
+        goto return_length;
     }
 
-    apr_snprintf(beacon_string, beacon_string_len+1+10,
-        "%s,%s,%s/%s,%s/%s,%s/%s,%s/%s,%s",
-        modsec, apache, apr, apr_loaded, pcre, pcre_loaded, lua, lua_loaded,
-        libxml, libxml_loaded, id);
-#endif
+    memset(hostname, '\0', sizeof(char) * max_length);
 
-    ap_log_error(APLOG_MARK, APLOG_NOTICE, 0, NULL,
-        "ModSecurity: StatusEngine call: \"%s\"", beacon_string);
+    msc_status_engine_base32_encode(hostname, plain_data, str_enc_len);
 
-    beacon_string_encoded = malloc(sizeof(char)*(strlen(beacon_string)*3));
-    if (!beacon_string_encoded) {
-        goto failed_beacon_string_encoded;
+    tmp = strdup(hostname);
+    if (tmp == NULL) {
+        length = -1;
+        goto failed_strdup;
     }
-    msc_status_engine_base32_encode(beacon_string_encoded, beacon_string,
-        strlen(beacon_string)*3);
 
-    beacon_string_encoded_splitted = malloc (sizeof(char) *
-        ((strlen(beacon_string_encoded)/STATUS_ENGINE_DNS_IN_BETWEEN_DOTS) +
-         strlen(beacon_string_encoded) + 1 + 1));
-    if (!beacon_string_encoded_splitted) {
-        goto failed_beacon_string_encoded_splitted;
+    str_enc_spl_len = msc_status_engine_fill_with_dots(hostname, tmp, max_length,
+        STATUS_ENGINE_DNS_IN_BETWEEN_DOTS);
+    if (str_enc_spl_len < 0) {
+        length = -1;
+        goto failed_enc_spl;
     }
 
-    msc_status_engine_fill_with_dots(beacon_string_encoded_splitted,
-        beacon_string_encoded,
-        (strlen(beacon_string_encoded)/STATUS_ENGINE_DNS_IN_BETWEEN_DOTS) +
-                     strlen(beacon_string_encoded) + 1 + 1,
-                     STATUS_ENGINE_DNS_IN_BETWEEN_DOTS);
+    apr_snprintf(hostname, max_length, "%s.%lu.%s", hostname, time(NULL),
+        STATUS_ENGINE_DNS_SUFFIX);
 
-    beacon_string_ready = malloc (sizeof(char) *
-        strlen(beacon_string_encoded_splitted) +
-        strlen(STATUS_ENGINE_DNS_SUFFIX) + 10 + 1);
+failed_enc_spl:
+    free(tmp);
+failed_strdup:
+return_length:
+failed_enc_spl_len:
+    return length;
+}
 
-    if (!beacon_string_ready) {
-        goto failed_beacon_string_ready;
+int msc_status_engine_call (void) {
+    char *beacon_str = NULL;
+    int beacon_str_len = 0;
+    char *hostname = NULL;
+    int hostname_len = 0;
+    int ret = -1;
+
+    /* Retrieve the beacon string */
+    beacon_str_len = msc_beacon_string(NULL, 0);
+
+    beacon_str = malloc(sizeof(char) * beacon_str_len);
+    if (beacon_str == NULL) {
+        goto failed_beacon_string_malloc;
     }
+    msc_beacon_string(beacon_str, beacon_str_len);
 
-    apr_snprintf(beacon_string_ready, strlen(beacon_string_encoded_splitted) +
-        strlen(STATUS_ENGINE_DNS_SUFFIX) + 12 + 1, "%s.%lu.%s",
-        beacon_string_encoded_splitted, time(NULL),
-        STATUS_ENGINE_DNS_SUFFIX);
+    ap_log_error(APLOG_MARK, APLOG_NOTICE, 0, NULL,
+            "ModSecurity: StatusEngine call: \"%s\"", beacon_str);
 
-    if (gethostbyname(beacon_string_ready)) {
+    /* Get beacon string in the format of a hostname */
+    hostname_len = msc_status_engine_prepare_hostname(NULL, beacon_str, 0);
+    if (hostname_len < 0) {
+        goto failed_hostname_len;
+    }
+
+    hostname = malloc(sizeof(char) * hostname_len);
+    if (hostname == NULL) {
+        goto failed_hostname_malloc;
+    }
+    hostname_len = msc_status_engine_prepare_hostname(hostname, beacon_str,
+            hostname_len);
+    if (hostname_len < 0) {
+        goto failed_hostname;
+    }
+
+    /* Perform the DNS query. */
+    if (gethostbyname(hostname)) {
         ap_log_error(APLOG_MARK, APLOG_NOTICE, 0, NULL,
             "ModSecurity: StatusEngine call successfully sent. For more " \
             "information visit: http://%s/", STATUS_ENGINE_DNS_SUFFIX);
     } else {
         ap_log_error(APLOG_MARK, APLOG_NOTICE, 0, NULL,
             "ModSecurity: StatusEngine call failed. Query: %s",
-            beacon_string_ready);
-    }
-
-    free(beacon_string_ready);
-failed_beacon_string_ready:
-    free(beacon_string_encoded_splitted);
-failed_beacon_string_encoded_splitted:
-    free(beacon_string_encoded);
-failed_beacon_string_encoded:
-    free(beacon_string);
-failed_beacon_string:
-    free(id);
-failed_id:
+            hostname);
+    }
+
+    ret = 0;
+
+failed_hostname:
+    free(hostname);
+failed_hostname_malloc:
+failed_hostname_len:
+    free(beacon_str);
+failed_beacon_string_malloc:
 
     return ret;
 }