use crate::profile::TlsProfile;
use crate::profile::extension::{PADDING, PRE_SHARED_KEY, advertised_extensions};
pub(crate) fn extension_ids(tls: &TlsProfile) -> Vec<u16> {
let mut ids = match tls.extension_permutation.as_deref() {
Some(order) => order.to_vec(),
None => advertised_extensions(tls, false)
.into_iter()
.map(|(id, _)| id)
.collect(),
};
if tls.padding {
ids.push(PADDING);
}
ids
}
pub(super) fn validate(tls: &TlsProfile, quic: bool) -> Result<(), String> {
validate_tail(tls, quic)?;
let Some(order) = tls.extension_permutation.as_deref() else {
return Ok(());
};
if order.is_empty() {
return Err(
"extension_permutation is empty; omit the key to accept BoringSSL's \
default extension order"
.to_string(),
);
}
let advertised = advertised_extensions(tls, quic);
for (index, id) in order.iter().enumerate() {
if *id == PRE_SHARED_KEY {
return Err(format!(
"extension_permutation entry {index} is pre_shared_key (0x{PRE_SHARED_KEY:04x}), \
which TLS 1.3 fixes last and BoringSSL will not reposition; drop it from the list"
));
}
if order[..index].contains(id) {
return Err(format!(
"extension_permutation repeats 0x{id:04x} at entry {index}; BoringSSL rejects a \
duplicated extension ID, leaving the ClientHello in its default order"
));
}
if !advertised.iter().any(|(known, _)| known == id) {
return Err(format!(
"extension_permutation entry {index} is 0x{id:04x}, which this profile never \
advertises; order only the extensions the [tls] block turns on"
));
}
}
let missing: Vec<String> = advertised
.iter()
.filter(|(id, _)| !order.contains(id))
.map(|(id, name)| format!("{name} (0x{id:04x})"))
.collect();
if !missing.is_empty() {
return Err(format!(
"extension_permutation omits {}; BoringSSL appends whatever the list leaves out, in \
its own order, so the tail of the ClientHello would not match the captured browser. \
Add each one at its captured position",
missing.join(", ")
));
}
Ok(())
}
fn validate_tail(tls: &TlsProfile, quic: bool) -> Result<(), String> {
if tls.extension_tail.is_empty() {
return Ok(());
}
if !quic || tls.grease || !tls.permute_extensions || tls.extension_permutation.is_some() {
return Err(
"extension_tail belongs in [h3.tls] with permute_extensions = true, grease = false \
and no extension_permutation; it pins the last extensions of a shuffled ClientHello"
.to_string(),
);
}
let advertised = advertised_extensions(tls, quic);
for (index, id) in tls.extension_tail.iter().enumerate() {
if *id == PRE_SHARED_KEY || tls.extension_tail[..index].contains(id) {
return Err(format!(
"extension_tail entry {index} (0x{id:04x}) is pre_shared_key or a repeat"
));
}
if !advertised.iter().any(|(known, _)| known == id) {
return Err(format!(
"extension_tail entry {index} is 0x{id:04x}, which this profile never advertises"
));
}
}
Ok(())
}