Minimal version of the LTE downgrade analyzer

This also renames the lte_parser crate to telcom_parser, since it'll
handle any 2G or 3G parsing going forward.

telcom-parser/src/lib.rs

@@ -0,0 +1,18 @@
+use asn1_codecs::{uper::UperCodec, PerCodecData, PerCodecError};
+use thiserror::Error;
+#[allow(unreachable_patterns, non_camel_case_types)]
+pub mod lte_rrc;
+
+#[derive(Error, Debug)]
+pub enum ParsingError {
+    #[error("Failed to decode UPER data: {0}")]
+    UperDecodeError(PerCodecError),
+}
+
+pub fn decode<T>(data: &[u8]) -> Result<T, ParsingError>
+    where T: UperCodec<Output = T>
+{
+    let mut asn_data = PerCodecData::from_slice_uper(data);
+    T::uper_decode(&mut asn_data)
+        .map_err(|e| ParsingError::UperDecodeError(e))
+}