Capture doesnt implement Iterator

[rukai]

Capture serves the purpose of an iterator: there is a next method. But it does not implement the Iterator trait making it difficult to compose with the rest of the rust ecosystem.

[Stargateur]

You can easily use from_fn() to create an iterator.

Thus I would advice to implement IntoIter and not Iterator directly on Capture.

[rukai]

Oh that from_fn is definitely handy.

But it turns out I dont actually want an iterator of Packets for my use case. What would be better is an iterator of an owned equivalent of Packet so that I can have multiple Packets alive at once. The current implementation of Packet only allows a single Packet to be alive at once due to lifetimes. Having multiple packets alive allows me to construct a vec and then rayon iterate over them.

This is what I ended up with locally:

pub struct OwnedPcapPacket {
    header: PcapPacketHeader,
    data: Vec<u8>,
}

impl OwnedPcapPacket {
    pub fn from(packet: PcapPacket) -> OwnedPcapPacket {
        OwnedPcapPacket {
            header: *packet.header,
            data: packet.data.to_owned(),
        }
    }
}

fn main() {
        let mut cap_handle = Capture::from_file(file_name).unwrap();

        let packets: Vec<_> =
            std::iter::from_fn(move || cap_handle.next().ok().map(OwnedPcapPacket::from)).collect();

        let parsed_packets: Vec<_> = packets
            .par_iter()
            .map(parse_packet(packet))
            .collect();
}

I think iteration logic + OwnedPcapPacket being provided by pcap would be nice but if adding such an owned packet struct + iteration is out of scope of pcap feel free to close the issue.

alternatively a way to have multiple Packet's alive at once would be even better and more performant, but I think thats a limitation of the underlying pcap library, havent looked into it closely at all though.

[Stargateur]

The pcap read packet by packet, thus the user need to copy the buffer provided, read more on https://www.tcpdump.org/manpages/pcap.3pcap.html. The strategy depend on what you need. On your case if you want read the file at once I don't see the problem of the code you show here.