net-file 0.1.3

This crate defines some operations on files and directories used in net-stalker project.
Documentation 
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use std::fmt;

use serde_derive::Serialize;

/// https://tshark.dev/formats/pcap_deconstruction/
// typedef struct pcap_hdr_s {
//     guint32 magic_number;   /* magic number */
//     guint16 version_major;  /* major version number */
//     guint16 version_minor;  /* minor version number */
//     gint32  thiszone;       /* GMT to local correction */
//     guint32 sigfigs;        /* accuracy of timestamps */
//     guint32 snaplen;        /* max length of captured packets, in octets */
//     guint32 network;        /* data link type */
// } pcap_hdr_t;
//
// Header size = 24 bytes:
///
/// ```
#[derive(Serialize)]
pub struct GlobalHeader {
    // magic_number = 4 bytes (d4 c3 b2 a1)
    // Magic Number Types https://tshark.dev/formats/pcap_deconstruction/
    magic_number: u32,
    // version_major = 2 bytes (02 00)
    version_major: u16,
    // version_minor = 2 bytes (04 00) *in our case 2.4. (little endian)
    version_minor: u16,
    // thiszone = 4 bytes (00 00 00 00) *usually set to 0
    thiszone: u32,
    // sigfigs = 4 bytes (00 00 00 00) *usually set to 0
    sigfigs: u32,
    // snaplen = 4 bytes (FF FF 00 00) *maximum length of the captured packets (data#) in bytes, here its 65535 (0xffff) which is default value for tcpdump and wireshark)
    snaplen: u32,
    // network = 4 bytes (01 00 00 00) *0x1 which indicates that the link-layer protocol is Ethernet.
    // Full list: http://www.tcpdump.org/linktypes.html
    network: u32,
}

const PCAPH_MAGIC_NUM_LE: u32 = 3569595041;
const PCAPH_VER_MAJOR: u16 = 2;
const PCAPH_VER_MINOR: u16 = 4;
const PCAPH_THISZONE: u32 = 0;
const PCAPH_SIGFIGS: u32 = 0;
const PCAPH_SNAPLEN: u32 = 65535;
const LINKTYPE_ETHERNET: u32 = 1;

impl Default for GlobalHeader {
    fn default() -> Self {
        let pcaph_magic_num_be = u32::from_be(PCAPH_MAGIC_NUM_LE);

        GlobalHeader {
            magic_number: pcaph_magic_num_be,
            version_major: PCAPH_VER_MAJOR,
            version_minor: PCAPH_VER_MINOR,
            thiszone: PCAPH_THISZONE,
            sigfigs: PCAPH_SIGFIGS,
            snaplen: PCAPH_SNAPLEN,
            network: LINKTYPE_ETHERNET,
        }
    }
}

impl fmt::Debug for GlobalHeader {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "GlobalHeader {{ magic_number={}, version_major={}, version_minor={}, thiszone={}, sigfigs={}, snaplen={}, network={}, binary={:?} }}",
               self.magic_number,
               self.version_major,
               self.version_minor,
               self.thiszone,
               self.sigfigs,
               self.snaplen,
               self.network,
               self.to_bytes())
    }
}

impl GlobalHeader {
    pub fn to_bytes(&self) -> Vec<u8> {
        bincode::serialize(&self).unwrap()
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    const PCAPH_MAGIC_NUM_BE: u32 = 2712847316;

    #[test]
    fn expected_create_global_header() {
        let global_header = GlobalHeader::default();
        let buf = global_header.to_bytes();

        println!("{:?}", global_header);
        assert_eq!(24, buf.len());
        assert_eq!(PCAPH_MAGIC_NUM_BE, global_header.magic_number);
        assert_eq!(PCAPH_VER_MAJOR, global_header.version_major);
        assert_eq!(PCAPH_VER_MINOR, global_header.version_minor);
        assert_eq!(PCAPH_THISZONE, global_header.thiszone);
        assert_eq!(PCAPH_SIGFIGS, global_header.sigfigs);
        assert_eq!(PCAPH_SNAPLEN, global_header.snaplen);
        assert_eq!(LINKTYPE_ETHERNET, global_header.network);
    }
}