[refactoring] Group all the CBOR util functions in cbor_util

This cl only moves all the CBOR utility functions in one place.
Some return error types are adjusted to adapt the change. There
should be no behavior change.

Bug: 310931749
Test: atest rialto_test
Change-Id: Ie3db9c93b1355d25d7d796818e19e554560e1f23
diff --git a/libs/bssl/Android.bp b/libs/bssl/Android.bp
index e1f4ffd..bed3dfb 100644
--- a/libs/bssl/Android.bp
+++ b/libs/bssl/Android.bp
@@ -23,6 +23,7 @@
     rustlibs: [
         "libbssl_avf_error_nostd",
         "libbssl_ffi_nostd",
+        "libcbor_util_nostd",
         "libciborium_nostd",
         "libcoset_nostd",
         "liblog_rust_nostd",
diff --git a/libs/bssl/error/Android.bp b/libs/bssl/error/Android.bp
index dc2902e..000e385 100644
--- a/libs/bssl/error/Android.bp
+++ b/libs/bssl/error/Android.bp
@@ -21,6 +21,8 @@
         "libcore.rust_sysroot",
     ],
     rustlibs: [
+        "libcoset_nostd",
+        "liblog_rust_nostd",
         "libserde_nostd",
     ],
 }
@@ -32,6 +34,8 @@
         "std",
     ],
     rustlibs: [
+        "libcoset",
+        "liblog_rust",
         "libserde",
     ],
 }
diff --git a/libs/bssl/error/src/lib.rs b/libs/bssl/error/src/lib.rs
index df79104..7f01c6c 100644
--- a/libs/bssl/error/src/lib.rs
+++ b/libs/bssl/error/src/lib.rs
@@ -38,6 +38,9 @@
     /// Failed to decode the COSE_Key.
     CoseKeyDecodingFailed,
 
+    /// An error occurred when interacting with the coset crate.
+    CosetError,
+
     /// Unimplemented operation.
     Unimplemented,
 }
@@ -50,11 +53,21 @@
             }
             Self::InternalError => write!(f, "An unexpected internal error occurred"),
             Self::CoseKeyDecodingFailed => write!(f, "Failed to decode the COSE_Key"),
+            Self::CosetError => {
+                write!(f, "An error occurred when interacting with the coset crate")
+            }
             Self::Unimplemented => write!(f, "Unimplemented operation"),
         }
     }
 }
 
+impl From<coset::CoseError> for Error {
+    fn from(e: coset::CoseError) -> Self {
+        log::error!("Coset error: {e}");
+        Self::CosetError
+    }
+}
+
 /// BoringSSL API names.
 #[allow(missing_docs)]
 #[allow(non_camel_case_types)]
diff --git a/libs/bssl/src/ec_key.rs b/libs/bssl/src/ec_key.rs
index 0c944cd..894934d 100644
--- a/libs/bssl/src/ec_key.rs
+++ b/libs/bssl/src/ec_key.rs
@@ -17,9 +17,7 @@
 
 use crate::cbb::CbbFixed;
 use crate::cbs::Cbs;
-use crate::util::{
-    check_int_result, get_label_value, get_label_value_as_bytes, to_call_failed_error,
-};
+use crate::util::{check_int_result, to_call_failed_error};
 use alloc::vec;
 use alloc::vec::Vec;
 use bssl_avf_error::{ApiName, Error, Result};
@@ -31,6 +29,7 @@
     EC_KEY_set_public_key_affine_coordinates, EC_POINT_get_affine_coordinates,
     NID_X9_62_prime256v1, NID_secp384r1, BIGNUM, EC_GROUP, EC_KEY, EC_POINT,
 };
+use cbor_util::{get_label_value, get_label_value_as_bytes};
 use ciborium::Value;
 use core::ptr::{self, NonNull};
 use coset::{
diff --git a/libs/bssl/src/evp.rs b/libs/bssl/src/evp.rs
index 86f99a8..fe3d88e 100644
--- a/libs/bssl/src/evp.rs
+++ b/libs/bssl/src/evp.rs
@@ -17,9 +17,7 @@
 use crate::cbb::CbbFixed;
 use crate::digest::{Digester, DigesterContext};
 use crate::ec_key::EcKey;
-use crate::util::{
-    check_int_result, get_label_value, get_label_value_as_bytes, to_call_failed_error,
-};
+use crate::util::{check_int_result, to_call_failed_error};
 use alloc::vec::Vec;
 use bssl_avf_error::{ApiName, Error, Result};
 use bssl_ffi::{
@@ -27,6 +25,7 @@
     EVP_PKEY_new_raw_public_key, EVP_PKEY_set1_EC_KEY, EVP_marshal_public_key, EVP_PKEY,
     EVP_PKEY_ED25519, EVP_PKEY_X25519,
 };
+use cbor_util::{get_label_value, get_label_value_as_bytes};
 use ciborium::Value;
 use core::ptr::{self, NonNull};
 use coset::{
diff --git a/libs/bssl/src/util.rs b/libs/bssl/src/util.rs
index 7473fe1..880c85b 100644
--- a/libs/bssl/src/util.rs
+++ b/libs/bssl/src/util.rs
@@ -16,8 +16,6 @@
 
 use crate::err::get_error_reason_code;
 use bssl_avf_error::{ApiName, Error, Result};
-use ciborium::Value;
-use coset::{CoseKey, Label};
 use log::error;
 
 pub(crate) fn check_int_result(ret: i32, api_name: ApiName) -> Result<()> {
@@ -37,14 +35,3 @@
 pub(crate) fn to_call_failed_error(api_name: ApiName) -> Error {
     Error::CallFailed(api_name, get_error_reason_code())
 }
-
-pub(crate) fn get_label_value_as_bytes(key: &CoseKey, label: Label) -> Result<&[u8]> {
-    Ok(get_label_value(key, label)?.as_bytes().ok_or_else(|| {
-        error!("Value not a bstr.");
-        Error::CoseKeyDecodingFailed
-    })?)
-}
-
-pub(crate) fn get_label_value(key: &CoseKey, label: Label) -> Result<&Value> {
-    Ok(&key.params.iter().find(|(k, _)| k == &label).ok_or(Error::CoseKeyDecodingFailed)?.1)
-}
diff --git a/libs/cborutil/Android.bp b/libs/cborutil/Android.bp
index 4758c4b..96dbf09 100644
--- a/libs/cborutil/Android.bp
+++ b/libs/cborutil/Android.bp
@@ -24,6 +24,7 @@
     rustlibs: [
         "libciborium_nostd",
         "libcoset_nostd",
+        "liblog_rust_nostd",
         "libserde_nostd",
     ],
 }
@@ -37,6 +38,7 @@
     rustlibs: [
         "libciborium",
         "libcoset",
+        "liblog_rust",
         "libserde",
     ],
 }
diff --git a/libs/cborutil/src/lib.rs b/libs/cborutil/src/lib.rs
index 2ec5af4..6e834f1 100644
--- a/libs/cborutil/src/lib.rs
+++ b/libs/cborutil/src/lib.rs
@@ -18,8 +18,11 @@
 
 extern crate alloc;
 
+use alloc::string::String;
 use alloc::vec::Vec;
-use coset::{CoseError, Result};
+use ciborium::value::{Integer, Value};
+use coset::{CoseError, CoseKey, Label, Result};
+use log::error;
 use serde::{de::DeserializeOwned, Serialize};
 
 /// Serializes the given data to a CBOR-encoded byte vector.
@@ -39,3 +42,88 @@
         Err(CoseError::ExtraneousData)
     }
 }
+
+/// Converts the provided value `v` to a value array.
+pub fn value_to_array(v: Value, context: &'static str) -> Result<Vec<Value>> {
+    v.into_array().map_err(|e| to_unexpected_item_error(&e, "array", context))
+}
+
+/// Converts the provided value `v` to a text string.
+pub fn value_to_text(v: Value, context: &'static str) -> Result<String> {
+    v.into_text().map_err(|e| to_unexpected_item_error(&e, "tstr", context))
+}
+
+/// Converts the provided value `v` to a map.
+pub fn value_to_map(v: Value, context: &'static str) -> Result<Vec<(Value, Value)>> {
+    v.into_map().map_err(|e| to_unexpected_item_error(&e, "map", context))
+}
+
+/// Converts the provided value `v` to a number.
+pub fn value_to_num<T: TryFrom<Integer>>(v: Value, context: &'static str) -> Result<T> {
+    let num = v.into_integer().map_err(|e| to_unexpected_item_error(&e, "int", context))?;
+    num.try_into().map_err(|_| {
+        error!("The provided value '{num:?}' is not a valid number: {context}");
+        CoseError::OutOfRangeIntegerValue
+    })
+}
+
+/// Converts the provided value `v` to a byte array of length `N`.
+pub fn value_to_byte_array<const N: usize>(v: Value, context: &'static str) -> Result<[u8; N]> {
+    let arr = value_to_bytes(v, context)?;
+    arr.try_into().map_err(|e| {
+        error!("The provided value '{context}' is not an array of length {N}: {e:?}");
+        CoseError::UnexpectedItem("bstr", "array of length {N}")
+    })
+}
+
+/// Converts the provided value `v` to bytes array.
+pub fn value_to_bytes(v: Value, context: &'static str) -> Result<Vec<u8>> {
+    v.into_bytes().map_err(|e| to_unexpected_item_error(&e, "bstr", context))
+}
+
+/// Builds a `CoseError::UnexpectedItem` error when the provided value `v` is not of the expected
+/// type `expected_type` and logs the error message with the provided `context`.
+pub fn to_unexpected_item_error(
+    v: &Value,
+    expected_type: &'static str,
+    context: &'static str,
+) -> CoseError {
+    let v_type = cbor_value_type(v);
+    assert!(v_type != expected_type);
+    error!("The provided value type '{v_type}' is not of type '{expected_type}': {context}");
+    CoseError::UnexpectedItem(v_type, expected_type)
+}
+
+/// Reads the type of the provided value `v`.
+pub fn cbor_value_type(v: &Value) -> &'static str {
+    match v {
+        Value::Integer(_) => "int",
+        Value::Bytes(_) => "bstr",
+        Value::Float(_) => "float",
+        Value::Text(_) => "tstr",
+        Value::Bool(_) => "bool",
+        Value::Null => "nul",
+        Value::Tag(_, _) => "tag",
+        Value::Array(_) => "array",
+        Value::Map(_) => "map",
+        _ => "other",
+    }
+}
+
+/// Returns the value of the given label in the given COSE key as bytes.
+pub fn get_label_value_as_bytes(key: &CoseKey, label: Label) -> Result<&[u8]> {
+    let v = get_label_value(key, label)?;
+    Ok(v.as_bytes().ok_or_else(|| {
+        to_unexpected_item_error(v, "bstr", "Get label value in CoseKey as bytes")
+    })?)
+}
+
+/// Returns the value of the given label in the given COSE key.
+pub fn get_label_value(key: &CoseKey, label: Label) -> Result<&Value> {
+    Ok(&key
+        .params
+        .iter()
+        .find(|(k, _)| k == &label)
+        .ok_or(CoseError::UnexpectedItem("", "Label not found in CoseKey"))?
+        .1)
+}