detect/transforms: in place modifications of buffers

As is the case when chaining multiple transforms.
Avoids using memcpy in these cases.

Add tests for these cases.

Ticket: 7409

rust/src/detect/transforms/compress_whitespace.rs

@@ -35,21 +35,16 @@ unsafe extern "C" fn compress_whitespace_setup(
 
 fn compress_whitespace_transform_do(input: &[u8], output: &mut [u8]) -> u32 {
     let mut nb = 0;
-    // seems faster than writing one byte at a time via
-    // for (i, o) in input.iter().filter(|c| !matches!(*c, b'\t' | b'\n' | b'\x0B' | b'\x0C' | b'\r' | b' ')).zip(output)
-    for subslice in
-        input.split_inclusive(|c| matches!(*c, b'\t' | b'\n' | b'\x0B' | b'\x0C' | b'\r' | b' '))
-    {
-        // a subslice of length 1 not at the beginning is a space following another space
-        if nb == 0
-            || subslice.len() > 1
-            || !matches!(
-                subslice[0],
-                b'\t' | b'\n' | b'\x0B' | b'\x0C' | b'\r' | b' '
-            )
-        {
-            output[nb..nb + subslice.len()].copy_from_slice(subslice);
-            nb += subslice.len();
+    let mut space = false;
+    for c in input {
+        if !matches!(*c, b'\t' | b'\n' | b'\x0B' | b'\x0C' | b'\r' | b' ') {
+            output[nb] = *c;
+            nb += 1;
+            space = false;
+        } else if !space {
+            output[nb] = *c;
+            nb += 1;
+            space = true;
         }
     }
     return nb as u32;
@@ -142,14 +137,22 @@ mod tests {
             exp.len() as u32
         );
         assert_eq!(&out[..exp.len()], exp);
-        let buf = b"I  \t J";
+        let mut buf = Vec::new();
+        buf.extend_from_slice(b"I  \t J");
         let mut out = vec![0; buf.len()];
         let exp = b"I J";
         assert_eq!(
-            compress_whitespace_transform_do(buf, &mut out),
+            compress_whitespace_transform_do(&buf, &mut out),
             exp.len() as u32
         );
         assert_eq!(&out[..exp.len()], exp);
+        // test in place
+        let still_buf = unsafe { std::slice::from_raw_parts(buf.as_ptr(), buf.len()) };
+        assert_eq!(
+            compress_whitespace_transform_do(still_buf, &mut buf),
+            exp.len() as u32
+        );
+        assert_eq!(&still_buf[..exp.len()], b"I J");
     }
 
     #[test]

rust/src/detect/transforms/dotprefix.rs

@@ -34,24 +34,32 @@ unsafe extern "C" fn dot_prefix_setup(
 }
 
 fn dot_prefix_transform_do(input: &[u8], output: &mut [u8]) {
+    if std::ptr::eq(output.as_ptr(), input.as_ptr()) {
+        output.copy_within(0..input.len(), 1);
+    } else {
+        output[1..].copy_from_slice(input);
+    }
     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 {
+    if 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;
     }
+    // get input after possible realloc
+    let input = InspectionBufferPtr(buffer);
+    if input.is_null() {
+        // allocation failure
+        return;
+    }
+    let input = build_slice!(input, input_len as usize);
     let output = std::slice::from_raw_parts_mut(output, (input_len + 1) as usize);
 
     dot_prefix_transform_do(input, output);
@@ -89,9 +97,15 @@ mod tests {
         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 buf = Vec::with_capacity(b"hello.example.com".len() + 1);
+        buf.extend_from_slice(b"hello.example.com");
         let mut out = vec![0; b"hello.example.com".len() + 1];
-        dot_prefix_transform_do(buf, &mut out);
+        dot_prefix_transform_do(&buf, &mut out);
         assert_eq!(out, b".hello.example.com");
+        // test in place
+        let still_buf = unsafe { std::slice::from_raw_parts(buf.as_ptr(), buf.len()) };
+        buf.push(b'.');
+        dot_prefix_transform_do(still_buf, &mut buf);
+        assert_eq!(&buf, b".hello.example.com");
     }
 }

rust/src/detect/transforms/hash.rs

@@ -231,9 +231,15 @@ mod tests {
 
     #[test]
     fn test_sha256_transform() {
-        let buf = b" A B C D ";
+        let mut buf = Vec::with_capacity(SC_SHA256_LEN);
+        buf.extend_from_slice(b" A B C D ");
         let mut out = vec![0; SC_SHA256_LEN];
-        sha256_transform_do(buf, &mut out);
+        sha256_transform_do(&buf, &mut out);
         assert_eq!(out, b"\xd6\xbf\x7d\x8d\x69\x53\x02\x4d\x0d\x84\x5c\x99\x9b\xae\x93\xcc\xac\x68\xea\xab\x9a\xc9\x77\xd0\xfd\x30\x6a\xf5\x9a\x3d\xe4\x3a");
+        // test in place
+        let still_buf = unsafe { std::slice::from_raw_parts(buf.as_ptr(), buf.len()) };
+        buf.resize(SC_SHA256_LEN, 0);
+        sha256_transform_do(still_buf, &mut buf);
+        assert_eq!(&buf, b"\xd6\xbf\x7d\x8d\x69\x53\x02\x4d\x0d\x84\x5c\x99\x9b\xae\x93\xcc\xac\x68\xea\xab\x9a\xc9\x77\xd0\xfd\x30\x6a\xf5\x9a\x3d\xe4\x3a");
     }
 }

rust/src/detect/transforms/http_headers.rs

@@ -103,11 +103,18 @@ unsafe extern "C" fn strip_pseudo_setup(
 
 fn strip_pseudo_transform_do(input: &[u8], output: &mut [u8]) -> u32 {
     let mut nb = 0;
+    let mut inb = 0;
+    let same = std::ptr::eq(output.as_ptr(), input.as_ptr());
     for subslice in input.split_inclusive(|c| *c == b'\n') {
         if !subslice.is_empty() && subslice[0] != b':' {
-            output[nb..nb + subslice.len()].copy_from_slice(subslice);
+            if same {
+                output.copy_within(inb..inb + subslice.len(), nb);
+            } else {
+                output[nb..nb + subslice.len()].copy_from_slice(subslice);
+            }
             nb += subslice.len();
         }
+        inb += subslice.len();
     }
     return nb as u32;
 }
@@ -183,5 +190,16 @@ mod tests {
         let mut out = vec![0; buf.len()];
         let nb = strip_pseudo_transform_do(buf, &mut out);
         assert_eq!(&out[..nb as usize], b"header2:Value2");
+        let mut buf = Vec::new();
+        buf.extend_from_slice(
+            b"Header1: Value1\n:method:get\nheader2:Value2\n:scheme:https\nheader3:Value3\n",
+        );
+        // test in place
+        let still_buf = unsafe { std::slice::from_raw_parts(buf.as_ptr(), buf.len()) };
+        let nb = strip_pseudo_transform_do(still_buf, &mut buf);
+        assert_eq!(
+            &still_buf[..nb as usize],
+            b"Header1: Value1\nheader2:Value2\nheader3:Value3\n"
+        );
     }
 }

rust/src/detect/transforms/strip_whitespace.rs

@@ -35,13 +35,15 @@ unsafe extern "C" fn strip_whitespace_setup(
 
 fn strip_whitespace_transform_do(input: &[u8], output: &mut [u8]) -> u32 {
     let mut nb = 0;
-    // seems faster than writing one byte at a time via
-    // for (i, o) in input.iter().filter(|c| !matches!(*c, b'\t' | b'\n' | b'\x0B' | b'\x0C' | b'\r' | b' ')).zip(output)
-    for subslice in input.split(|c| matches!(*c, b'\t' | b'\n' | b'\x0B' | b'\x0C' | b'\r' | b' '))
+    for (i, o) in input
+        .iter()
+        .filter(|c| !matches!(*c, b'\t' | b'\n' | b'\x0B' | b'\x0C' | b'\r' | b' '))
+        .zip(output)
     {
-        output[nb..nb + subslice.len()].copy_from_slice(subslice);
-        nb += subslice.len();
+        *o = *i;
+        nb += 1;
     }
+    // do not use faster copy_from_slice because input and output may overlap (point to the same data)
     return nb as u32;
 }
 
@@ -124,13 +126,21 @@ mod tests {
         );
         assert_eq!(&out[..exp.len()], exp);
 
-        let buf = b"I  \t J";
+        let mut buf = Vec::new();
+        buf.extend_from_slice(b"I  \t J");
         let mut out = vec![0; buf.len()];
         let exp = b"IJ";
         assert_eq!(
-            strip_whitespace_transform_do(buf, &mut out),
+            strip_whitespace_transform_do(&buf, &mut out),
             exp.len() as u32
         );
         assert_eq!(&out[..exp.len()], exp);
+        // test in place
+        let still_buf = unsafe { std::slice::from_raw_parts(buf.as_ptr(), buf.len()) };
+        assert_eq!(
+            strip_whitespace_transform_do(still_buf, &mut buf),
+            exp.len() as u32
+        );
+        assert_eq!(&still_buf[..exp.len()], b"IJ");
     }
 }

rust/src/detect/transforms/urldecode.rs

@@ -135,9 +135,14 @@ mod tests {
 
     #[test]
     fn test_url_decode_transform() {
-        let buf = b"Suricata%20is+%27%61wesome%21%27%25%30%30%ZZ%4";
+        let mut buf = Vec::new();
+        buf.extend_from_slice(b"Suricata%20is+%27%61wesome%21%27%25%30%30%ZZ%4");
         let mut out = vec![0; buf.len()];
-        let nb = url_decode_transform_do(buf, &mut out);
+        let nb = url_decode_transform_do(&buf, &mut out);
         assert_eq!(&out[..nb as usize], b"Suricata is 'awesome!'%00%ZZ%4");
+        // test in place
+        let still_buf = unsafe { std::slice::from_raw_parts(buf.as_ptr(), buf.len()) };
+        let nb = url_decode_transform_do(still_buf, &mut buf);
+        assert_eq!(&still_buf[..nb as usize], b"Suricata is 'awesome!'%00%ZZ%4");
     }
 }

rust/src/detect/transforms/xor.rs

@@ -143,10 +143,15 @@ mod tests {
 
     #[test]
     fn test_xor_transform() {
-        let buf = b"example.com";
+        let mut buf = Vec::new();
+        buf.extend_from_slice(b"example.com");
         let mut out = vec![0; buf.len()];
         let ctx = xor_parse_do("0a0DC8ff").unwrap();
-        xor_transform_do(buf, &mut out, &ctx);
+        xor_transform_do(&buf, &mut out, &ctx);
         assert_eq!(out, b"ou\xa9\x92za\xad\xd1ib\xa5");
+        // test in place
+        let still_buf = unsafe { std::slice::from_raw_parts(buf.as_ptr(), buf.len()) };
+        xor_transform_do(still_buf, &mut buf, &ctx);
+        assert_eq!(&still_buf, b"ou\xa9\x92za\xad\xd1ib\xa5");
     }
 }