transforms: move dotprefix to rust

Ticket: 7229

Author: catenacyber

rust/src/detect/transforms/dotprefix.rs

@@ -0,0 +1,97 @@
+/* Copyright (C) 2024 Open Information Security Foundation
+ *
+ * You can copy, redistribute or modify this Program under the terms of
+ * the GNU General Public License version 2 as published by the Free
+ * Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * version 2 along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+use super::{
+    DetectHelperTransformRegister, DetectSignatureAddTransform, InspectionBufferCheckAndExpand,
+    InspectionBufferLength, InspectionBufferPtr, InspectionBufferTruncate, SCTransformTableElmt,
+};
+use crate::detect::SIGMATCH_NOOPT;
+
+use std::os::raw::{c_int, c_void};
+use std::ptr;
+
+static mut G_TRANSFORM_DOT_PREFIX_ID: c_int = 0;
+
+#[no_mangle]
+unsafe extern "C" fn dot_prefix_setup(
+    _de: *mut c_void, s: *mut c_void, _raw: *const std::os::raw::c_char,
+) -> c_int {
+    return DetectSignatureAddTransform(s, G_TRANSFORM_DOT_PREFIX_ID, ptr::null_mut());
+}
+
+fn dot_prefix_transform_do(input: &[u8], output: &mut [u8]) {
+    output[0] = b'.';
+    output[1..].copy_from_slice(input);
+}
+
+#[no_mangle]
+unsafe extern "C" fn dot_prefix_transform(buffer: *mut c_void, _ctx: *mut c_void) {
+    let input = InspectionBufferPtr(buffer);
+    let input_len = InspectionBufferLength(buffer);
+    if input.is_null() || input_len == 0 {
+        return;
+    }
+    let input = build_slice!(input, input_len as usize);
+
+    let output = InspectionBufferCheckAndExpand(buffer, input_len + 1);
+    if output.is_null() {
+        // allocation failure
+        return;
+    }
+    let output = std::slice::from_raw_parts_mut(output, (input_len + 1) as usize);
+
+    dot_prefix_transform_do(input, output);
+
+    InspectionBufferTruncate(buffer, input_len + 1);
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn DetectTransformDotPrefixRegister() {
+    let kw = SCTransformTableElmt {
+        name: b"dotprefix\0".as_ptr() as *const libc::c_char,
+        desc: b"modify buffer to extract the dotprefix\0".as_ptr() as *const libc::c_char,
+        url: b"/rules/transforms.html#dotprefix\0".as_ptr() as *const libc::c_char,
+        Setup: dot_prefix_setup,
+        flags: SIGMATCH_NOOPT,
+        Transform: dot_prefix_transform,
+        Free: None,
+        TransformValidate: None,
+    };
+    unsafe {
+        G_TRANSFORM_DOT_PREFIX_ID = DetectHelperTransformRegister(&kw);
+        if G_TRANSFORM_DOT_PREFIX_ID < 0 {
+            SCLogWarning!("Failed registering transform dot_prefix");
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_dot_prefix_transform() {
+        let buf = b"example.com";
+        let mut out = vec![0; b"example.com".len() + 1];
+        dot_prefix_transform_do(buf, &mut out);
+        assert_eq!(out, b".example.com");
+        let buf = b"hello.example.com";
+        let mut out = vec![0; b"hello.example.com".len() + 1];
+        dot_prefix_transform_do(buf, &mut out);
+        assert_eq!(out, b".hello.example.com");
+    }
+}

rust/src/detect/transforms/mod.rs

@@ -20,6 +20,7 @@
 use std::os::raw::{c_char, c_int, c_void};
 
 pub mod compress_whitespace;
+pub mod dotprefix;
 pub mod strip_whitespace;
 
 #[repr(C)]

src/Makefile.am

@@ -308,7 +308,6 @@ noinst_HEADERS = \
 	detect-tos.h \
 	detect-transform-base64.h \
 	detect-transform-casechange.h \
-	detect-transform-dotprefix.h \
 	detect-transform-header-lowercase.h \
 	detect-transform-md5.h \
 	detect-transform-pcrexform.h \
@@ -879,7 +878,6 @@ libsuricata_c_a_SOURCES = \
 	detect-tos.c \
 	detect-transform-base64.c \
 	detect-transform-casechange.c \
-	detect-transform-dotprefix.c \
 	detect-transform-header-lowercase.c \
 	detect-transform-md5.c \
 	detect-transform-pcrexform.c \

src/detect-engine-register.c

@@ -220,7 +220,6 @@
 #include "detect-transform-md5.h"
 #include "detect-transform-sha1.h"
 #include "detect-transform-sha256.h"
-#include "detect-transform-dotprefix.h"
 #include "detect-transform-pcrexform.h"
 #include "detect-transform-urldecode.h"
 #include "detect-transform-xor.h"