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Don't panic if a long command is sent and the backend reports no support for extended length

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This case should not happen during normal operation with the pcsc backend. But the condition was triggered in tests with an alternate CardBackend implementation (see: https://gitlab.com/openpgp-card/openpgp-card/-/issues/69).
This commit is contained in:
Heiko Schaefer 2023-04-13 18:15:58 +02:00
parent 629eecd510
commit 4a042d703f
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GPG key ID: 4A849A1904CCBD7D
1 changed files with 9 additions and 11 deletions
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20
openpgp-card/src/apdu/command.rs
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@ -81,7 +81,7 @@ impl Command {
let nc = self.data.len() as u16; let nc = self.data.len() as u16;
let mut buf = vec![self.cla, self.ins, self.p1, self.p2]; let mut buf = vec![self.cla, self.ins, self.p1, self.p2];
buf.extend(Self::make_lc(nc, ext_len)); buf.extend(Self::make_lc(nc, ext_len)?);
buf.extend(&self.data); buf.extend(&self.data);
buf.extend(Self::make_le(nc, ext_len, expect_response)); buf.extend(Self::make_le(nc, ext_len, expect_response));
@ -89,21 +89,19 @@ impl Command {
} }
/// Encode len for Lc field /// Encode len for Lc field
fn make_lc(len: u16, ext_len: bool) -> Vec<u8> { fn make_lc(len: u16, ext_len: bool) -> Result<Vec<u8>, crate::Error> {
if !ext_len { if !ext_len && len > 0xff {
assert!( return Err(crate::Error::InternalError(format!(
len <= 0xff, "Command len = {len:x?}, but extended length is unsupported by backend"
"{}", )));
"unexpected: len = {len:x?}, but ext says Short"
);
} }
if len == 0 { if len == 0 {
vec![] Ok(vec![])
} else if !ext_len { } else if !ext_len {
vec![len as u8] Ok(vec![len as u8])
} else { } else {
vec![0, (len >> 8) as u8, (len & 255) as u8] Ok(vec![0, (len >> 8) as u8, (len & 255) as u8])
} }
} }