add apkverify lib to verify APK/APEX signatures
`verify(apk)` is an entry for a Signature Verification of APK/APEX.
For now, it only parses signing block and does barely no verification
yet. Verification will be implemented in follow-up changes.
Cargo.toml is added for `cargo test`, but will be removed when
Android.bp is added.
Bug: 190343842
Test: cargo test
Change-Id: Ib95128e021e8da50a015d302c9c394a8b5a98957
diff --git a/apkverify/src/bytes_ext.rs b/apkverify/src/bytes_ext.rs
new file mode 100644
index 0000000..61848ad
--- /dev/null
+++ b/apkverify/src/bytes_ext.rs
@@ -0,0 +1,97 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+//! Provides extension methods Bytes::read<T>(), which calls back ReadFromBytes::read_from_byte()
+
+use anyhow::{bail, Result};
+use bytes::{Buf, Bytes};
+use std::ops::Deref;
+
+#[derive(Clone)]
+pub struct LengthPrefixed<T> {
+ inner: T,
+}
+
+impl<T> Deref for LengthPrefixed<T> {
+ type Target = T;
+ fn deref(&self) -> &Self::Target {
+ &self.inner
+ }
+}
+
+pub trait BytesExt {
+ fn read<T: ReadFromBytes>(&mut self) -> Result<T>;
+}
+
+impl BytesExt for Bytes {
+ fn read<T: ReadFromBytes>(&mut self) -> Result<T> {
+ T::read_from_bytes(self)
+ }
+}
+
+pub trait ReadFromBytes {
+ fn read_from_bytes(buf: &mut Bytes) -> Result<Self>
+ where
+ Self: Sized;
+}
+
+impl ReadFromBytes for u32 {
+ fn read_from_bytes(buf: &mut Bytes) -> Result<Self> {
+ Ok(buf.get_u32_le())
+ }
+}
+
+impl<T: ReadFromBytes> ReadFromBytes for Vec<T> {
+ fn read_from_bytes(buf: &mut Bytes) -> Result<Self> {
+ let mut result = vec![];
+ while buf.has_remaining() {
+ result.push(buf.read()?);
+ }
+ Ok(result)
+ }
+}
+
+impl<T: ReadFromBytes> ReadFromBytes for LengthPrefixed<T> {
+ fn read_from_bytes(buf: &mut Bytes) -> Result<Self> {
+ let mut inner = read_length_prefixed_slice(buf)?;
+ let inner = inner.read()?;
+ Ok(LengthPrefixed { inner })
+ }
+}
+
+impl ReadFromBytes for Bytes {
+ fn read_from_bytes(buf: &mut Bytes) -> Result<Self> {
+ Ok(buf.slice(..))
+ }
+}
+
+fn read_length_prefixed_slice(buf: &mut Bytes) -> Result<Bytes> {
+ if buf.remaining() < 4 {
+ bail!(
+ "Remaining buffer too short to contain length of length-prefixed field. Remaining: {}",
+ buf.remaining()
+ );
+ }
+ let len = buf.get_u32_le() as usize;
+ if len > buf.remaining() {
+ bail!(
+ "length-prefixed field longer than remaining buffer. Field length: {}, remaining: {}",
+ len,
+ buf.remaining()
+ );
+ }
+ Ok(buf.split_to(len))
+}