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https://github.com/EFForg/rayhunter.git
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Kismet GPS option section per packet dcriped, refactoring to reduce loc
This commit is contained in:
Carlos Guerra
committed by
Will Greenberg
Will Greenberg
parent
adb316e2d7
commit
66f0c2a336
+21
-131
@@ -6,8 +6,7 @@ use crate::gsmtap::GsmtapMessage;
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use chrono::prelude::*;
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use deku::prelude::*;
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use pcap_file_tokio::pcapng::PcapNgWriter;
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use pcap_file_tokio::pcapng::RawBlock;
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use pcap_file_tokio::pcapng::blocks::enhanced_packet::EnhancedPacketBlock;
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use pcap_file_tokio::pcapng::blocks::enhanced_packet::{EnhancedPacketBlock, EnhancedPacketOption};
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use pcap_file_tokio::pcapng::blocks::interface_description::InterfaceDescriptionBlock;
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use pcap_file_tokio::pcapng::blocks::section_header::{SectionHeaderBlock, SectionHeaderOption};
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use pcap_file_tokio::{Endianness, PcapError};
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@@ -27,87 +26,11 @@ pub enum GsmtapPcapError {
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Deku(#[from] DekuError),
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}
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/// A GPS fix to embed in each PCAP packet as a Kismet-compatible custom option.
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///
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/// Set `timestamp_unix_secs = 0` to signal a fixed/synthetic coordinate (no real GPS time).
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pub struct KismetGpsPoint {
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pub struct GpsPoint {
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pub latitude: f64,
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pub longitude: f64,
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pub timestamp_unix_secs: u32,
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}
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// Block type constant for Enhanced Packet Block (pcapng spec §4.3)
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const ENHANCED_PACKET_BLOCK: u32 = 0x00000006;
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/// Serialises a Kismet GPS custom option into a byte buffer suitable for
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/// appending directly to an EPB body.
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///
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/// Wire layout (section is big-endian; GPS custom payload is little-endian per
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/// Kismet convention):
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///
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/// option_code u16 BE = 2989 (custom binary, non-copyable)
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/// option_len u16 BE = 24 (PEN 4 + payload 20)
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/// pen u32 BE = 55922 (Kismet IANA PEN)
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/// --- custom payload (20 bytes, all fields little-endian) ---
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/// magic u8 = 0x47
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/// version u8 = 0x01
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/// fields_len u16 LE = 16 (bitmask + lon + lat + ts)
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/// bitmask u32 LE = 0x26 (lon=0x2, lat=0x4, gps_time=0x20)
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/// longitude i32 LE fixed37 (degrees × 1e7)
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/// latitude i32 LE fixed37 (degrees × 1e7)
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/// gps_time u32 LE unix seconds (0 = fixed/unknown)
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/// --- end-of-options marker ---
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/// end_code u16 BE = 0
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/// end_len u16 BE = 0
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fn build_gps_option_bytes(gps: &KismetGpsPoint) -> Vec<u8> {
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// --- opt_comment (code 1): human-readable GPS for Wireshark ---
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// Format chosen to match what Kismet writes so tools see a consistent label.
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let comment = if gps.timestamp_unix_secs == 0 {
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format!("GPS fixed lat={:.7} lon={:.7}", gps.latitude, gps.longitude)
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} else {
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format!("GPS lat={:.7} lon={:.7} ts={}", gps.latitude, gps.longitude, gps.timestamp_unix_secs)
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};
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let comment_bytes = comment.as_bytes();
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let comment_pad = (4 - (comment_bytes.len() % 4)) % 4;
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// --- Kismet GPS custom option (code 2989) ---
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let lon_fixed: i32 = (gps.longitude * 1e7) as i32;
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let lat_fixed: i32 = (gps.latitude * 1e7) as i32;
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// Custom payload: 20 bytes, all little-endian (Kismet convention)
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let fields_len: u16 = 16; // bitmask(4) + lon(4) + lat(4) + ts(4)
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let bitmask: u32 = 0x2 | 0x4 | 0x20; // lon | lat | gps_time
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let mut payload = Vec::<u8>::with_capacity(20);
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payload.push(0x47); // magic
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payload.push(0x01); // version
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payload.extend_from_slice(&fields_len.to_le_bytes());
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payload.extend_from_slice(&bitmask.to_le_bytes());
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payload.extend_from_slice(&lon_fixed.to_le_bytes());
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payload.extend_from_slice(&lat_fixed.to_le_bytes());
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payload.extend_from_slice(&gps.timestamp_unix_secs.to_le_bytes());
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// payload is exactly 20 bytes, already 4-byte aligned
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// option_len = PEN (4) + payload (20) = 24, also 4-byte aligned
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let gps_opt_len: u16 = 24;
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let mut out = Vec::new();
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// opt_comment header + value + padding (big-endian section)
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out.extend_from_slice(&1u16.to_be_bytes()); // option_code = 1
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out.extend_from_slice(&(comment_bytes.len() as u16).to_be_bytes()); // option_len
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out.extend_from_slice(comment_bytes);
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out.extend_from_slice(&[0u8; 3][..comment_pad]); // padding to 4-byte boundary
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// Kismet GPS option header + PEN + custom payload (big-endian section, LE payload)
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out.extend_from_slice(&2989u16.to_be_bytes()); // option_code
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out.extend_from_slice(&gps_opt_len.to_be_bytes());
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out.extend_from_slice(&55922u32.to_be_bytes()); // PEN
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out.extend_from_slice(&payload);
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// end-of-options marker (big-endian)
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out.extend_from_slice(&0u16.to_be_bytes());
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out.extend_from_slice(&0u16.to_be_bytes());
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out
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/// Unix timestamp of the GPS fix. 0 means fixed/synthetic (no real GPS time).
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pub unix_ts: u32,
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}
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pub struct GsmtapPcapWriter<T>
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@@ -186,7 +109,7 @@ where
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&mut self,
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msg: GsmtapMessage,
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timestamp: Timestamp,
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gps: Option<&KismetGpsPoint>,
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gps: Option<&GpsPoint>,
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) -> Result<(), GsmtapPcapError> {
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let duration = timestamp
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.to_datetime()
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@@ -223,56 +146,23 @@ where
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data.extend(&udp_header.to_bytes()?);
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data.extend(&msg_bytes);
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match gps {
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None => {
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// Fast path: delegate to the library's standard EPB writer.
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let packet = EnhancedPacketBlock {
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interface_id: 0,
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timestamp: duration,
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original_len: data.len() as u32,
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data: Cow::Owned(data),
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options: vec![],
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};
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self.writer.write_pcapng_block(packet).await?;
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}
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Some(gps_point) => {
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// GPS path: build a raw EPB body so we can append the Kismet
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// custom option directly. The pcap-file-tokio crate does not
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// expose the inner option types publicly, so we must write the
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// option bytes manually and wrap them in a RawBlock.
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//
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// All standard pcapng multi-byte fields are big-endian (section
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// header declares Endianness::Big); the GPS custom payload uses
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// little-endian per the Kismet convention.
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let pad_len = (4 - (data.len() % 4)) % 4;
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let ts_nanos = duration.as_nanos();
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let ts_high = (ts_nanos >> 32) as u32;
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let ts_low = (ts_nanos & 0xFFFFFFFF) as u32;
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let gps_bytes = build_gps_option_bytes(gps_point);
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// Body = EPB fixed header (20 B) + data + padding + gps options
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let body_len = 20 + data.len() + pad_len + gps_bytes.len();
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let mut body = Vec::<u8>::with_capacity(body_len);
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body.extend_from_slice(&0u32.to_be_bytes()); // interface_id
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body.extend_from_slice(&ts_high.to_be_bytes()); // timestamp high
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body.extend_from_slice(&ts_low.to_be_bytes()); // timestamp low
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body.extend_from_slice(&(data.len() as u32).to_be_bytes()); // captured_len
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body.extend_from_slice(&(data.len() as u32).to_be_bytes()); // original_len
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body.extend_from_slice(&data);
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body.extend_from_slice(&[0u8; 3][..pad_len]); // padding
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body.extend_from_slice(&gps_bytes);
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let block_total_len = (12 + body.len()) as u32;
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let raw = RawBlock {
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type_: ENHANCED_PACKET_BLOCK,
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initial_len: block_total_len,
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body: Cow::Owned(body),
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trailer_len: block_total_len,
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};
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self.writer.write_raw_block(&raw).await?;
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}
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let mut options = vec![];
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if let Some(p) = gps {
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let comment = if p.unix_ts == 0 {
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format!("GPS fixed lat={:.7} lon={:.7}", p.latitude, p.longitude)
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} else {
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format!("GPS lat={:.7} lon={:.7} ts={}", p.latitude, p.longitude, p.unix_ts)
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};
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options.push(EnhancedPacketOption::Comment(Cow::Owned(comment)));
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}
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let packet = EnhancedPacketBlock {
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interface_id: 0,
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timestamp: duration,
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original_len: data.len() as u32,
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data: Cow::Owned(data),
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options,
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};
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self.writer.write_pcapng_block(packet).await?;
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self.ip_id = self.ip_id.wrapping_add(1);
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Ok(())
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