411 lines
14 KiB
Rust
411 lines
14 KiB
Rust
use super::*;
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use range_set_blaze::RangeSetBlaze;
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use std::io::{Error, ErrorKind};
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use std::sync::atomic::{AtomicU16, Ordering};
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// AssemblyBuffer Version 1 properties
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const VERSION_1: u8 = 1;
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type LengthType = u16;
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type SequenceType = u16;
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const HEADER_LEN: usize = 8;
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const MAX_LEN: usize = LengthType::MAX as usize;
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// XXX: keep statistics on all drops and why we dropped them
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// XXX: move to config eventually?
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const FRAGMENT_LEN: usize = 1280 - HEADER_LEN;
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const MAX_CONCURRENT_HOSTS: usize = 256;
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const MAX_ASSEMBLIES_PER_HOST: usize = 256;
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const MAX_BUFFER_PER_HOST: usize = 256 * 1024;
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const MAX_ASSEMBLY_AGE_US: u64 = 10_000_000;
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/////////////////////////////////////////////////////////
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#[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
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struct PeerKey {
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remote_addr: SocketAddr,
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}
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#[derive(Clone, Eq, PartialEq)]
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struct MessageAssembly {
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timestamp: u64,
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seq: SequenceType,
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data: Vec<u8>,
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parts: RangeSetBlaze<LengthType>,
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}
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#[derive(Clone, Eq, PartialEq)]
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struct PeerMessages {
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total_buffer: usize,
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assemblies: VecDeque<MessageAssembly>,
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}
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impl PeerMessages {
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pub fn new() -> Self {
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Self {
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total_buffer: 0,
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assemblies: VecDeque::new(),
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}
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}
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fn merge_in_data(
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&mut self,
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timestamp: u64,
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ass: usize,
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off: LengthType,
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len: LengthType,
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chunk: &[u8],
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) -> bool {
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let assembly = &mut self.assemblies[ass];
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// Ensure the new fragment hasn't redefined the message length, reusing the same seq
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if assembly.data.len() != len as usize {
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// Drop the assembly and just go with the new fragment as starting a new assembly
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let seq = assembly.seq;
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self.remove_assembly(ass);
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self.new_assembly(timestamp, seq, off, len, chunk);
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return false;
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}
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let part_start = off;
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let part_end = off + chunk.len() as LengthType - 1;
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let part = RangeSetBlaze::from_iter([part_start..=part_end]);
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// if fragments overlap, drop the old assembly and go with a new one
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if !assembly.parts.is_disjoint(&part) {
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let seq = assembly.seq;
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self.remove_assembly(ass);
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self.new_assembly(timestamp, seq, off, len, chunk);
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return false;
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}
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// Merge part
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assembly.parts |= part;
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assembly.data[part_start as usize..=part_end as usize].copy_from_slice(chunk);
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// Check to see if this part is done
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if assembly.parts.ranges_len() == 1
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&& assembly.parts.first().unwrap() == 0
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&& assembly.parts.last().unwrap() == len - 1
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{
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return true;
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}
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false
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}
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fn new_assembly(
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&mut self,
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timestamp: u64,
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seq: SequenceType,
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off: LengthType,
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len: LengthType,
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chunk: &[u8],
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) -> usize {
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// ensure we have enough space for the new assembly
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self.reclaim_space(len as usize);
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// make the assembly
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let part_start = off;
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let part_end = off + chunk.len() as LengthType - 1;
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let mut assembly = MessageAssembly {
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timestamp,
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seq,
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data: vec![0u8; len as usize],
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parts: RangeSetBlaze::from_iter([part_start..=part_end]),
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};
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assembly.data[part_start as usize..=part_end as usize].copy_from_slice(chunk);
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// Add the buffer length in
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self.total_buffer += assembly.data.len();
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self.assemblies.push_front(assembly);
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// Was pushed front, return the front index
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0
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}
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fn remove_assembly(&mut self, index: usize) -> MessageAssembly {
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let assembly = self.assemblies.remove(index).unwrap();
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self.total_buffer -= assembly.data.len();
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assembly
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}
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fn truncate_assemblies(&mut self, new_len: usize) {
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for an in new_len..self.assemblies.len() {
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self.total_buffer -= self.assemblies[an].data.len();
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}
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self.assemblies.truncate(new_len);
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}
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fn reclaim_space(&mut self, needed_space: usize) {
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// If we have too many assemblies or too much buffer rotate some out
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while self.assemblies.len() > (MAX_ASSEMBLIES_PER_HOST - 1)
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|| self.total_buffer > (MAX_BUFFER_PER_HOST - needed_space)
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{
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self.remove_assembly(self.assemblies.len() - 1);
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}
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}
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pub fn insert_fragment(
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&mut self,
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seq: SequenceType,
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off: LengthType,
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len: LengthType,
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chunk: &[u8],
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) -> Option<Vec<u8>> {
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// Get the current timestamp
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let cur_ts = get_timestamp();
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// Get the assembly this belongs to by its sequence number
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let mut ass = None;
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for an in 0..self.assemblies.len() {
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// If this assembly's timestamp is too old, then everything after it will be too, drop em all
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let age = cur_ts.saturating_sub(self.assemblies[an].timestamp);
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if age > MAX_ASSEMBLY_AGE_US {
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self.truncate_assemblies(an);
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break;
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}
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// If this assembly has a matching seq, then assemble with it
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if self.assemblies[an].seq == seq {
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ass = Some(an);
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}
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}
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if ass.is_none() {
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// Add a new assembly to the front and return the first index
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self.new_assembly(cur_ts, seq, off, len, chunk);
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return None;
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}
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let ass = ass.unwrap();
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// Now that we have an assembly, merge in the fragment
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let done = self.merge_in_data(cur_ts, ass, off, len, chunk);
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// If the assembly is now equal to the entire range, then return it
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if done {
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let assembly = self.remove_assembly(ass);
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return Some(assembly.data);
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}
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// Otherwise, do nothing
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None
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}
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}
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/////////////////////////////////////////////////////////
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struct AssemblyBufferInner {
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peer_message_map: HashMap<PeerKey, PeerMessages>,
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}
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struct AssemblyBufferUnlockedInner {
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outbound_lock_table: AsyncTagLockTable<SocketAddr>,
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next_seq: AtomicU16,
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}
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/// Packet reassembly and fragmentation handler
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/// No retry, no acknowledgment, no flow control
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/// Just trying to survive lower path MTU for larger messages
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#[derive(Clone)]
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pub struct AssemblyBuffer {
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inner: Arc<Mutex<AssemblyBufferInner>>,
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unlocked_inner: Arc<AssemblyBufferUnlockedInner>,
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}
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impl AssemblyBuffer {
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fn new_unlocked_inner() -> AssemblyBufferUnlockedInner {
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AssemblyBufferUnlockedInner {
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outbound_lock_table: AsyncTagLockTable::new(),
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next_seq: AtomicU16::new(0),
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}
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}
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fn new_inner() -> AssemblyBufferInner {
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AssemblyBufferInner {
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peer_message_map: HashMap::new(),
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}
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}
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pub fn new() -> Self {
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Self {
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inner: Arc::new(Mutex::new(Self::new_inner())),
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unlocked_inner: Arc::new(Self::new_unlocked_inner()),
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}
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}
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/// Receive a packet chunk and add to the message assembly
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/// if a message has been completely, return it
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pub fn insert_frame(
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&self,
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frame: &[u8],
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remote_addr: SocketAddr,
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) -> NetworkResult<Option<Vec<u8>>> {
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// If we receive a zero length frame, send it
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if frame.len() == 0 {
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return NetworkResult::value(Some(frame.to_vec()));
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}
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// If we receive a frame smaller than or equal to the length of the header, drop it
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// or if this frame is larger than our max message length, then drop it
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if frame.len() <= HEADER_LEN || frame.len() > MAX_LEN {
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#[cfg(feature = "network-result-extra")]
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return NetworkResult::invalid_message(format!(
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"invalid header length: frame.len={}",
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frame.len()
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));
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#[cfg(not(feature = "network-result-extra"))]
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return NetworkResult::invalid_message("invalid header length");
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}
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// --- Decode the header
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// Drop versions we don't understand
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if frame[0] != VERSION_1 {
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#[cfg(feature = "network-result-extra")]
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return NetworkResult::invalid_message(format!(
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"invalid frame version: frame[0]={}",
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frame[0]
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));
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#[cfg(not(feature = "network-result-extra"))]
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return NetworkResult::invalid_message("invalid frame version");
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}
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// Version 1 header
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let seq = SequenceType::from_be_bytes(frame[2..4].try_into().unwrap());
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let off = LengthType::from_be_bytes(frame[4..6].try_into().unwrap());
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let len = LengthType::from_be_bytes(frame[6..HEADER_LEN].try_into().unwrap());
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let chunk = &frame[HEADER_LEN..];
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// See if we have a whole message and not a fragment
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if off == 0 && len as usize == chunk.len() {
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return NetworkResult::value(Some(chunk.to_vec()));
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}
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// Drop fragments with offsets greater than or equal to the message length
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if off >= len {
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#[cfg(feature = "network-result-extra")]
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return NetworkResult::invalid_message(format!(
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"offset greater than length: off={} >= len={}",
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off, len
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));
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#[cfg(not(feature = "network-result-extra"))]
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return NetworkResult::invalid_message("offset greater than length");
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}
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// Drop fragments where the chunk would be applied beyond the message length
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if off as usize + chunk.len() > len as usize {
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#[cfg(feature = "network-result-extra")]
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return NetworkResult::invalid_message(format!(
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"chunk applied beyond message length: off={} + chunk.len={} > len={}",
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off,
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chunk.len(),
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len
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));
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#[cfg(not(feature = "network-result-extra"))]
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return NetworkResult::invalid_message("chunk applied beyond message length");
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}
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// Get or create the peer message assemblies
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// and drop the packet if we have too many peers
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let mut inner = self.inner.lock();
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let peer_key = PeerKey { remote_addr };
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let peer_count = inner.peer_message_map.len();
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match inner.peer_message_map.entry(peer_key) {
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std::collections::hash_map::Entry::Occupied(mut e) => {
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let peer_messages = e.get_mut();
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// Insert the fragment and see what comes out
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let out = peer_messages.insert_fragment(seq, off, len, chunk);
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// If we are returning a message, see if there are any more assemblies for this peer
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// If not, remove the peer
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if out.is_some() {
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if peer_messages.assemblies.len() == 0 {
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e.remove();
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}
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}
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NetworkResult::value(out)
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}
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std::collections::hash_map::Entry::Vacant(v) => {
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// See if we have room for one more
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if peer_count == MAX_CONCURRENT_HOSTS {
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return NetworkResult::value(None);
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}
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// Add the peer
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let peer_messages = v.insert(PeerMessages::new());
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// Insert the fragment and see what comes out
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NetworkResult::value(peer_messages.insert_fragment(seq, off, len, chunk))
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}
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}
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}
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/// Add framing to chunk to send to the wire
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fn frame_chunk(chunk: &[u8], offset: usize, message_len: usize, seq: SequenceType) -> Vec<u8> {
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assert!(chunk.len() > 0);
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assert!(message_len <= MAX_LEN);
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assert!(offset + chunk.len() <= message_len);
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let off: LengthType = offset as LengthType;
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let len: LengthType = message_len as LengthType;
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unsafe {
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// Uninitialized vector, careful!
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let mut out = unaligned_u8_vec_uninit(chunk.len() + HEADER_LEN);
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// Write out header
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out[0] = VERSION_1;
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out[1] = 0; // reserved
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out[2..4].copy_from_slice(&seq.to_be_bytes()); // sequence number
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out[4..6].copy_from_slice(&off.to_be_bytes()); // offset of chunk inside message
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out[6..HEADER_LEN].copy_from_slice(&len.to_be_bytes()); // total length of message
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// Write out body
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out[HEADER_LEN..].copy_from_slice(chunk);
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out
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}
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}
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/// Split a message into packets and send them serially, ensuring
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/// that they are sent consecutively to a particular remote address,
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/// never interleaving packets from one message and other to minimize reassembly problems
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pub async fn split_message<S, F>(
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&self,
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data: Vec<u8>,
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remote_addr: SocketAddr,
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mut sender: S,
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) -> std::io::Result<NetworkResult<()>>
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where
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S: FnMut(Vec<u8>, SocketAddr) -> F,
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F: Future<Output = std::io::Result<NetworkResult<()>>>,
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{
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if data.len() > MAX_LEN {
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return Err(Error::from(ErrorKind::InvalidData));
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}
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// Do not frame or split anything zero bytes long, just send it
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if data.len() == 0 {
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return sender(data, remote_addr).await;
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}
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// Lock per remote addr
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let _tag_lock = self
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.unlocked_inner
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.outbound_lock_table
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.lock_tag(remote_addr)
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.await;
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// Get a message seq
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let seq = self.unlocked_inner.next_seq.fetch_add(1, Ordering::Relaxed);
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// Chunk it up
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let mut offset = 0usize;
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let message_len = data.len();
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for chunk in data.chunks(FRAGMENT_LEN) {
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// Frame chunk
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let framed_chunk = Self::frame_chunk(chunk, offset, message_len, seq);
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// Send chunk
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network_result_try!(sender(framed_chunk, remote_addr).await?);
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// Go to next chunk
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offset += chunk.len()
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}
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Ok(NetworkResult::value(()))
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}
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}
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