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Dev/replace fasthash #58

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merged 4 commits into from
Nov 26, 2024
Merged

Dev/replace fasthash #58

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239b302
libpcap-analyzer: better wording for worker identifiers in trace/debug
pc-anssi Nov 25, 2024
47fadea
Remove fasthash and use toeplitz hash to dispatch jobs (Closes #57)
pc-anssi Nov 25, 2024
3b3d6dd
libpcap-analyzer: implement Toeplitz and XOR+xxHash RSS functions
pc-anssi Nov 25, 2024
e892c57
libpcap-analyzer: use XOR+FNV instead of XOR+XXH2 (xxHash32 breaks ou…
pc-anssi Nov 25, 2024
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1 change: 0 additions & 1 deletion libpcap-analyzer/Cargo.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -35,7 +35,6 @@ plugin_tls_stats = ["rusticata","tls-parser"]
base16ct = { version="0.2", features=["alloc"], optional=true }
base64ct = { version="1.5", features=["alloc"], optional=true }
crossbeam-channel = "0.5"
fasthash = "0.4"
fnv = "1.0"
indexmap = { version="2.2", features=["serde"] }
lazy_static = "1.2"
Expand Down
102 changes: 89 additions & 13 deletions libpcap-analyzer/src/threaded_analyzer.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,7 @@ use libpcap_tools::*;
use pcap_parser::data::PacketData;
use pnet_packet::ethernet::{EtherType, EtherTypes, EthernetPacket};
use std::cmp::min;
use std::hash::Hasher;
use std::panic::AssertUnwindSafe;
use std::sync::{Arc, Barrier};
use std::thread;
Expand Down Expand Up @@ -208,21 +209,91 @@ pub(crate) fn extern_dispatch_l3<'a>(
ethertype: EtherType,
) -> Result<(), Error> {
let n_workers = jobs.len();
let i = fan_out(data, ethertype, n_workers);
let i = softrss_xor_fnv(data, ethertype, n_workers);
debug_assert!(i < n_workers);
// trace!("sending job to worker {i}");
jobs[i]
.send(Job::New(packet, ctx.clone(), data, ethertype))
.or(Err(Error::Generic("Error while sending job")))
}

fn fan_out(data: &[u8], ethertype: EtherType, n_workers: usize) -> usize {
#[allow(dead_code)]
fn softrss_toeplitz(data: &[u8], ethertype: EtherType, n_workers: usize) -> usize {
use crate::toeplitz::{toeplitz_hash_aligned32_v2, AlignedU8, SYMMETRIC_KEY_U32BE};
match ethertype {
EtherTypes::Ipv4 => {
if data.len() >= 20 {
let mut aligned = AlignedU8([0; 20]);
let buf = &mut aligned.0;
let sz = 8;
let src_dst_addrs = &data[12..20];
buf[0..sz].copy_from_slice(src_dst_addrs);
// we may append source and destination ports
// XXX breaks fragmentation
// if data[9] == crate::plugin::TRANSPORT_TCP || data[9] == crate::plugin::TRANSPORT_UDP {
// if data.len() >= 24 {
// // source port, in network-order
// buf[8] = data[20];
// buf[9] = data[21];
// // destination port, in network-order
// buf[10] = data[22];
// buf[11] = data[23];
// sz = 12;
// }
// }
let hash = toeplitz_hash_aligned32_v2(SYMMETRIC_KEY_U32BE, &buf[..sz]);

// debug!("{:?} -- hash --> 0x{:x}", buf, hash);
// ((hash >> 24) ^ (hash & 0xff)) as usize % n_workers
hash as usize % n_workers
} else {
n_workers - 1
}
}
EtherTypes::Ipv6 => {
if data.len() >= 40 {
let mut aligned = AlignedU8([0; 40]);
let buf = &mut aligned.0;
let sz = 40;
let src_dst_addrs = &data[8..40];
buf[0..sz].copy_from_slice(src_dst_addrs);
// we may append source and destination ports
// XXX breaks fragmentation
// if data[6] == crate::plugin::TRANSPORT_TCP || data[6] == crate::plugin::TRANSPORT_UDP {
// if data.len() >= 44 {
// // source port, in network-order
// buf[33] = data[40];
// buf[34] = data[41];
// // destination port, in network-order
// buf[35] = data[42];
// buf[36] = data[43];
// sz += 4;
// }
// }
let hash = toeplitz_hash_aligned32_v2(SYMMETRIC_KEY_U32BE, &buf[..sz]);

// debug!("{:?} -- hash --> 0x{:x}", buf, hash);
// ((hash >> 24) ^ (hash & 0xff)) as usize % n_workers
hash as usize % n_workers
} else {
n_workers - 1
}
}
_ => 0,
}
}

// Receive-Side Scaling (RSS) based on XOR function and Fowler–Noll–Vo (FNV) hash function
// NOTE: This seems to be balanced less evenly than toeplitz hash, but still good
#[allow(dead_code)]
fn softrss_xor_fnv(data: &[u8], ethertype: EtherType, n_workers: usize) -> usize {
// This seed is just random data. It has no cryptographic value, it is just used to
// seed the hash function
const SEED: u64 = 0x3d58_216b_caff_e84b;

match ethertype {
EtherTypes::Ipv4 => {
if data.len() >= 20 {
// let src = &data[12..15];
// let dst = &data[16..19];
// let proto = data[9];
// (src[0] ^ dst[0] ^ proto) as usize % n_workers
let mut buf: [u8; 20] = [0; 20];
let sz = 4;
buf[0] = data[12] ^ data[16];
Expand All @@ -242,8 +313,11 @@ fn fan_out(data: &[u8], ethertype: EtherType, n_workers: usize) -> usize {
// sz = 12;
// }
// }
// let hash = crate::toeplitz::toeplitz_hash(crate::toeplitz::KEY, &buf[..sz]);
let hash = fasthash::metro::hash64(&buf[..sz]);

let mut hasher = fnv::FnvHasher::with_key(SEED);
hasher.write(&buf[..sz]);
let hash = hasher.finish();

// debug!("{:?} -- hash --> 0x{:x}", buf, hash);
// ((hash >> 24) ^ (hash & 0xff)) as usize % n_workers
hash as usize % n_workers
Expand Down Expand Up @@ -274,8 +348,10 @@ fn fan_out(data: &[u8], ethertype: EtherType, n_workers: usize) -> usize {
// sz += 4;
// }
// }
// let hash = crate::toeplitz::toeplitz_hash(crate::toeplitz::KEY, &buf[..sz]);
let hash = fasthash::metro::hash64(&buf[..sz]);
let mut hasher = fnv::FnvHasher::with_key(SEED);
hasher.write(&buf[..sz]);
let hash = hasher.finish();

// debug!("{:?} -- hash --> 0x{:x}", buf, hash);
// ((hash >> 24) ^ (hash & 0xff)) as usize % n_workers
hash as usize % n_workers
Expand All @@ -296,21 +372,21 @@ fn worker(mut a: Analyzer, idx: usize, r: Receiver<Job>, barrier: Arc<Barrier>)
Job::Exit => break,
Job::PrintDebug => {
{
debug!("thread {}: hash table size: {}", idx, a.flows.len());
debug!("worker {}: flow table size: {}", idx, a.flows.len());
};
}
Job::New(packet, ctx, data, ethertype) => {
pcap_index = ctx.pcap_index;
let span = span!(Level::DEBUG, "worker", pcap_index);
let _enter = span.enter();
trace!("thread {}: got a job", idx);
trace!("worker {}: got a job", idx);
let h3_res = handle_l3(&packet, &ctx, data, ethertype, &mut a);
if h3_res.is_err() {
warn!("thread {}: handle_l3 failed", idx);
}
}
Job::Wait => {
trace!("Thread {}: waiting at barrier", idx);
trace!("worker {}: waiting at barrier", idx);
barrier.wait();
}
}
Expand Down
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