sim: Always compute protected size
Instead of having a running size that we try to always match the encoded
size of, compute it a bit more dynamically. The size is still needed
before the contents can be filled in, so this doesn't gain too much, but
will make it easier to compute the rest of the TLV size based on the
actual encoding rather than lots of magic numbers.
Signed-off-by: David Brown <david.brown@linaro.org>
diff --git a/sim/src/tlv.rs b/sim/src/tlv.rs
index 80d82ae..ad53c27 100644
--- a/sim/src/tlv.rs
+++ b/sim/src/tlv.rs
@@ -100,8 +100,6 @@
kinds: Vec<TlvKinds>,
/// The total size of the payload.
size: u16,
- /// Extra bytes of the TLV that are protected.
- protect_size: u16,
payload: Vec<u8>,
dependencies: Vec<Dependency>,
enc_key: Vec<u8>,
@@ -256,17 +254,16 @@
}
fn protect_size(&self) -> u16 {
- if self.protect_size == 0 {
+ if self.dependencies.is_empty() {
0
} else {
- // Include the protected size, as well as the TLV header.
- 4 + self.protect_size
+ // Include the header and space for each dependency.
+ 4 + (self.dependencies.len() as u16) * (4 + 4 + 8)
}
}
fn add_dependency(&mut self, id: u8, version: &ImageVersion) {
let my_size = 4 + 4 + 8;
- self.protect_size += my_size;
self.size += my_size;
self.dependencies.push(Dependency {
id: id,
@@ -282,10 +279,11 @@
fn make_tlv(self: Box<Self>) -> Vec<u8> {
let mut protected_tlv: Vec<u8> = vec![];
- if self.protect_size > 0 {
+ if self.protect_size() > 0 {
protected_tlv.push(0x08);
protected_tlv.push(0x69);
- protected_tlv.write_u16::<LittleEndian>(self.protect_size()).unwrap();
+ let size = self.protect_size();
+ protected_tlv.write_u16::<LittleEndian>(size).unwrap();
for dep in &self.dependencies {
protected_tlv.write_u16::<LittleEndian>(TlvKinds::DEPENDENCY as u16).unwrap();
protected_tlv.write_u16::<LittleEndian>(12).unwrap();
@@ -300,6 +298,8 @@
protected_tlv.write_u16::<LittleEndian>(dep.version.revision).unwrap();
protected_tlv.write_u32::<LittleEndian>(dep.version.build_num).unwrap();
}
+
+ assert_eq!(size, protected_tlv.len() as u16, "protected TLV length incorrect");
}
// Ring does the signature itself, which means that it must be