lib: add lte-parser crate support

This'll let us convert a Gsmtap message into a fully parsed LTE
message.

lib/src/lib.rs

@@ -7,3 +7,4 @@ pub mod log_codes;
 pub mod gsmtap;
 pub mod gsmtap_parser;
 pub mod pcap;
+pub mod lte_rrc;

lib/src/lte_rrc.rs

@@ -0,0 +1,71 @@
+use lte_parser::{decode, lte_rrc};
+use thiserror::Error;
+use super::gsmtap::{GsmtapType, LteRrcSubtype, GsmtapMessage};
+
+#[derive(Error, Debug)]
+pub enum MessageParsingError {
+    #[error("Failed decoding")]
+    DecodingError(#[from] lte_parser::ParsingError),
+    #[error("Unknown Gsmtap message type {0:?}")]
+    UnknownGsmtapType(GsmtapType),
+    #[error("Unsupported LTE RRC subtype {0:?}")]
+    UnsupportedLteRrcSubtype(LteRrcSubtype),
+}
+
+#[derive(Debug, Clone, PartialEq)]
+pub enum Message {
+    DlCcch(lte_rrc::DL_CCCH_Message),
+    DlDcch(lte_rrc::DL_DCCH_Message),
+    UlCcch(lte_rrc::UL_CCCH_Message),
+    UlDcch(lte_rrc::UL_DCCH_Message),
+    BcchBch(lte_rrc::BCCH_BCH_Message),
+    BcchDlSch(lte_rrc::BCCH_DL_SCH_Message),
+    PCCH(lte_rrc::PCCH_Message),
+    MCCH(lte_rrc::MCCH_Message),
+    ScMcch(lte_rrc::SC_MCCH_Message_r13),
+    BcchBchMbms(lte_rrc::BCCH_BCH_Message_MBMS),
+    BcchDlSchBr(lte_rrc::BCCH_DL_SCH_Message_BR),
+    BcchDlSchMbms(lte_rrc::BCCH_DL_SCH_Message_MBMS),
+    SbcchSlBch(lte_rrc::SBCCH_SL_BCH_Message),
+    SbcchSlBchV2x(lte_rrc::SBCCH_SL_BCH_Message_V2X_r14),
+
+    // FIXME: unclear which message these "NB" types map to
+    //DlCcchNb(),
+    //DlDcchNb(),
+    //UlCcchNb(),
+    //UlDcchNb(),
+    //BcchBchNb(),
+    //BcchBchTddNb(),
+    //BcchDlSchNb(),
+    //PcchNb(),
+    //ScMcchNb(),
+}
+
+impl TryFrom<&GsmtapMessage> for Message {
+    type Error = MessageParsingError;
+
+    fn try_from(gsmtap_msg: &GsmtapMessage) -> Result<Self, Self::Error> {
+        if let GsmtapType::LteRrc(lte_rrc_subtype) = gsmtap_msg.header.gsmtap_type {
+            use LteRrcSubtype as L;
+            use Message as R;
+            return match lte_rrc_subtype {
+                L::DlCcch => Ok(R::DlCcch(decode(&gsmtap_msg.payload)?)),
+                L::DlDcch => Ok(R::DlDcch(decode(&gsmtap_msg.payload)?)),
+                L::UlCcch => Ok(R::UlCcch(decode(&gsmtap_msg.payload)?)),
+                L::UlDcch => Ok(R::UlDcch(decode(&gsmtap_msg.payload)?)),
+                L::BcchBch => Ok(R::BcchBch(decode(&gsmtap_msg.payload)?)),
+                L::BcchDlSch => Ok(R::BcchDlSch(decode(&gsmtap_msg.payload)?)),
+                L::PCCH => Ok(R::PCCH(decode(&gsmtap_msg.payload)?)),
+                L::MCCH => Ok(R::MCCH(decode(&gsmtap_msg.payload)?)),
+                L::ScMcch => Ok(R::ScMcch(decode(&gsmtap_msg.payload)?)),
+                L::BcchBchMbms => Ok(R::BcchBchMbms(decode(&gsmtap_msg.payload)?)),
+                L::BcchDlSchBr => Ok(R::BcchDlSchBr(decode(&gsmtap_msg.payload)?)),
+                L::BcchDlSchMbms => Ok(R::BcchDlSchMbms(decode(&gsmtap_msg.payload)?)),
+                L::SbcchSlBch => Ok(R::SbcchSlBch(decode(&gsmtap_msg.payload)?)),
+                L::SbcchSlBchV2x => Ok(R::SbcchSlBchV2x(decode(&gsmtap_msg.payload)?)),
+                subtype => Err(MessageParsingError::UnsupportedLteRrcSubtype(subtype)),
+            };
+        }
+        Err(MessageParsingError::UnknownGsmtapType(gsmtap_msg.header.gsmtap_type))
+    }
+}