c_its_parser/pcap/
mod.rs

1use alloc::string::ToString;
2
3/// Strips Radiotap, IEEE 802.11p and LLC headers from a binary message buffer
4///
5/// Convenience function combining [`remove_radiotap_hdr`], [`remove_80211_hdr`] and [`remove_llc_hdr`].
6///
7/// # Errors
8/// Returns a human-readable error when parsing failed
9pub fn remove_pcap_headers(data: &[u8]) -> Result<&[u8], alloc::string::String> {
10    remove_radiotap_hdr(data).and_then(remove_wlan_headers)
11}
12
13/// Strips IEEE 802.11p and LLC headers from a binary message buffer
14///
15/// Convenience function combining [`remove_80211_hdr`] and [`remove_llc_hdr`].
16///
17/// IEEE 802.11 data frames always have an LLC header.
18/// Since `remove_80211_hdr` only allows data frames, we usually need to remove them, too.
19///
20/// # Errors
21/// Returns a human-readable error when parsing failed
22pub fn remove_wlan_headers(data: &[u8]) -> Result<&[u8], alloc::string::String> {
23    remove_80211_hdr(data).and_then(remove_llc_hdr)
24}
25
26/// Strips Radiotap header from a binary message buffer
27///
28/// # Errors
29/// Return a human-readable error when parsing failed
30pub fn remove_radiotap_hdr(data: &[u8]) -> Result<&[u8], alloc::string::String> {
31    extract_radiotap_hdr(data).map(|(_, remaining)| remaining)
32}
33
34/// Extracts Radiotap header from a binary message buffer and returns the header and remaining buffer
35///
36/// # Errors
37/// Return a human-readable error when parsing failed
38pub fn extract_radiotap_hdr(data: &[u8]) -> Result<(&[u8], &[u8]), alloc::string::String> {
39    /*
40     * Radiotap Header has the following format
41     * - u_int8_t   header version (currently always zero)
42     * - u_int8_t   (padding for byte alignment);
43     * - u_int16_t  entire header length;
44     * - u_int32_t  bitmask which subsequent data is present
45     */
46
47    let radiotap_version: u8 = data[0];
48    if radiotap_version != 0 {
49        return Err(alloc::format!(
50            "Unknown header version {radiotap_version:#x}"
51        ));
52    }
53
54    let hdr_len: usize = u16::from_le_bytes([data[2], data[3]]).into();
55    Ok(data.split_at(hdr_len))
56}
57
58/// Strips IEEE 802.11p header from a binary message buffer
59///
60/// # Errors
61/// Return a human-readable error when parsing failed
62pub fn remove_80211_hdr(data: &[u8]) -> Result<&[u8], alloc::string::String> {
63    extract_80211_hdr(data).map(|(_, remaining)| remaining)
64}
65
66/// Extracts IEEE 802.11p header from a binary message buffer and returns the header and remaining buffer
67///
68/// # Errors
69/// Return a human-readable error when parsing failed
70pub fn extract_80211_hdr(data: &[u8]) -> Result<(&[u8], &[u8]), alloc::string::String> {
71    /*
72     * IEEE 802.11 Header has the following format (24-26 bytes)
73     * - 2 bytes frame control
74     *      byte 0: .... ..00: Version 0
75     *      byte 0: .... 10..: Type data frame
76     *      byte 0: 1000 ....: QoS Data (or 0 for non-QoS data)
77     * - 2 bytes duration
78     * - 6 bytes addr 1 (receiver)
79     * - 6 bytes addr 2 (transmitter)
80     * - 6 bytes addr 3 (BSSID)
81     * - 2 bytes sequence control
82     * - addr 4 not used in 802.11p mode
83     * - 0 or 2 bytes QOS control
84     * - HT control not used in 802.11p mode
85     */
86
87    let ieee80211_framecontrol: u8 = data[0];
88
89    let ieee80211_fc_version: u8 = ieee80211_framecontrol & 0x03; // 0000.00xx
90    if ieee80211_fc_version != 0 {
91        return Err(
92            alloc::format!("Unknown 802.11 header version {ieee80211_fc_version}").to_string(),
93        );
94    }
95
96    let ieee80211_fc_type: u8 = (ieee80211_framecontrol & 0x0c) >> 2; // 0000.xx00
97    if ieee80211_fc_type != 0b10 {
98        // only select data frames
99        return Err(
100            alloc::format!("Unsupported 802.11 frame type {ieee80211_fc_type}").to_string(),
101        );
102    }
103
104    let ieee80211_fc_subtype: u8 = (ieee80211_framecontrol & 0xf0) >> 4; // xxxx.0000
105    let qos_hdr_bytes = if ieee80211_fc_subtype == 0b1000 {
106        2
107    } else if ieee80211_fc_subtype == 0b0000 {
108        0
109    } else {
110        // only select QoS or "normal" data frames
111        return Err(
112            alloc::format!("Unsupported 802.11 frame subtype {ieee80211_fc_subtype:#04x}")
113                .to_string(),
114        );
115    };
116
117    let hdr_len: usize = 24 + qos_hdr_bytes;
118    Ok(data.split_at(hdr_len))
119}
120
121/// Strips LLC header from a binary message buffer
122///
123/// # Errors
124/// Return a human-readable error when parsing failed
125pub fn remove_llc_hdr(data: &[u8]) -> Result<&[u8], alloc::string::String> {
126    extract_llc_hdr(data).map(|(_, remaining)| remaining)
127}
128
129/// Extracts LLC header from a binary message buffer and returns the header and remaining buffer
130///
131/// # Errors
132/// Return a human-readable error when parsing failed
133pub fn extract_llc_hdr(data: &[u8]) -> Result<(&[u8], &[u8]), alloc::string::String> {
134    /*
135     * LLC Header has the following format (8 bytes)
136     * - 1 bytes DSAP
137     * - 1 bytes SSAP
138     * - 1 bytes control field
139     * - 3 bytes organization code
140     * - 2 bytes Type (0x8947 BE is GeoNetworking)
141     */
142
143    let llc_type: u16 = (u16::from(data[6]) << 8) | u16::from(data[7]);
144
145    if llc_type != 0x8947 {
146        return Err(alloc::format!("Unknown LLC payload type {llc_type:#x}").to_string());
147    }
148
149    let hdr_len: usize = 8; // TODO: Is this the right size?
150    Ok(data.split_at(hdr_len))
151}
c_its_parser/pcap/mod.rs

c_its_parser/pcap/
mod.rs
