Lots more stuff, but mostly packet defragmentation.

network-hypervisor/src/crypto/mod.rs

@@ -9,21 +9,8 @@ pub mod random;
 pub mod secret;
 
 pub use aes_gmac_siv;
-use std::convert::Infallible;
-
-static mut SALT64: u64 = 0;
 
 pub fn init() {
-    unsafe {
-        // We always run gcrypt in "FIPS mode," but it doesn't count as fully compliant unless it's a FIPS-certified library.
-        let _ = gcrypt::init_fips_mode(|_| -> Result<(), Infallible> { Ok(()) });
-
-        while SALT64 == 0 {
-            let mut tmp = 0_u64;
-            gcrypt::rand::randomize(gcrypt::rand::Level::Strong, &mut *((&mut tmp as *mut u64).cast::<[u8; 8]>()));
-            SALT64 = tmp;
-        }
-    }
+    // We always run gcrypt in "FIPS mode," but it doesn't count as fully compliant unless it's a FIPS-certified library.
+    let _ = gcrypt::init_fips_mode(|_| -> Result<(), std::convert::Infallible> { Ok(()) });
 }
-
-pub fn salt64() -> u64 { unsafe { SALT64 } }

network-hypervisor/src/util/gate.rs

@@ -0,0 +1,67 @@
+use std::sync::atomic::{AtomicI64, Ordering};
+
+/// Boolean rate limiter with normal (non-atomic) semantics.
+pub struct IntervalGate<const FREQ: i64>(i64);
+
+impl<const FREQ: i64> Default for IntervalGate<FREQ> {
+    fn default() -> Self {
+        Self(0)
+    }
+}
+
+impl<const FREQ: i64> IntervalGate<FREQ> {
+    #[inline(always)]
+    pub fn new(initial_ts: i64) -> Self {
+        Self(initial_ts)
+    }
+
+    #[inline(always)]
+    pub fn reset(&mut self) {
+        self.0 = 0;
+    }
+
+    #[inline(always)]
+    pub fn gate(&mut self, time: i64) -> bool {
+        if (time - self.0) >= FREQ {
+            self.0 = time;
+            true
+        } else {
+            false
+        }
+    }
+}
+
+/// Boolean rate limiter with atomic semantics.
+pub struct AtomicIntervalGate<const FREQ: i64>(AtomicI64);
+
+impl<const FREQ: i64> Default for AtomicIntervalGate<FREQ> {
+    fn default() -> Self {
+        Self(AtomicI64::new(0))
+    }
+}
+
+impl<const FREQ: i64> AtomicIntervalGate<FREQ> {
+    #[inline(always)]
+    pub fn new(initial_ts: i64) -> Self {
+        Self(AtomicI64::new(initial_ts))
+    }
+
+    #[inline(always)]
+    pub fn reset(&self) {
+        self.0.store(0, Ordering::Relaxed);
+    }
+
+    #[inline(always)]
+    pub fn gate(&self, time: i64) -> bool {
+        // Note that if two or more threads are using this at once, any thread's time might
+        // end up being the one stored. This is okay since these times should either be the
+        // same or very close, and slight differences won't cause issues with the use cases
+        // for this. This is primarily used to rate gate operations to prevent DOS attacks.
+        if (time - self.0.load(Ordering::Relaxed)) >= FREQ {
+            self.0.store(time, Ordering::Relaxed);
+            true
+        } else {
+            false
+        }
+    }
+}

network-hypervisor/src/util/hex.rs

@@ -12,7 +12,7 @@ pub fn to_string(b: &[u8]) -> String {
     s
 }
 
-/// Encode an unsigned 64-bit value as a string.
+/// Encode an unsigned 64-bit value as a hexadecimal string.
 pub fn to_string_u64(mut i: u64, skip_leading_zeroes: bool) -> String {
     let mut s = String::new();
     s.reserve(16);
@@ -26,7 +26,7 @@ pub fn to_string_u64(mut i: u64, skip_leading_zeroes: bool) -> String {
     s
 }
 
-/// Encode an unsigned 64-bit value as a string.
+/// Encode an unsigned 64-bit value as a hexadecimal ASCII string.
 pub fn to_vec_u64(mut i: u64, skip_leading_zeroes: bool) -> Vec<u8> {
     let mut s = Vec::new();
     s.reserve(16);
@@ -40,7 +40,7 @@ pub fn to_vec_u64(mut i: u64, skip_leading_zeroes: bool) -> Vec<u8> {
     s
 }
 
-/// Decode a hex string, ignoring non-hexadecimal characters.
+/// Decode a hex string, ignoring all non-hexadecimal characters.
 pub fn from_string(s: &str) -> Vec<u8> {
     let mut b: Vec<u8> = Vec::new();
     b.reserve((s.len() / 2) + 1);

network-hypervisor/src/util/mod.rs

@@ -1,5 +1,6 @@
 pub mod hex;
 pub mod pool;
+pub mod gate;
 
 pub(crate) const ZEROES: [u8; 64] = [0_u8; 64];
 

network-hypervisor/src/vl1/address.rs

@@ -1,7 +1,7 @@
 use std::str::FromStr;
 use std::hash::{Hash, Hasher};
 
-use crate::vl1::constants::ADDRESS_RESERVED_PREFIX;
+use crate::vl1::constants::{ADDRESS_RESERVED_PREFIX, ADDRESS_SIZE};
 use crate::error::InvalidFormatError;
 use crate::util::hex::HEX_CHARS;
 
@@ -11,7 +11,7 @@ pub struct Address(u64);
 impl Address {
     #[inline(always)]
     pub fn from_bytes(b: &[u8]) -> Result<Address, InvalidFormatError> {
-        if b.len() >= 5 {
+        if b.len() >= ADDRESS_SIZE {
             Ok(Address((b[0] as u64) << 32 | (b[1] as u64) << 24 | (b[2] as u64) << 16 | (b[3] as u64) << 8 | b[4] as u64))
         } else {
             Err(InvalidFormatError)
@@ -34,7 +34,7 @@ impl Address {
     }
 
     #[inline(always)]
-    pub fn to_bytes(&self) -> [u8; 5] {
+    pub fn to_bytes(&self) -> [u8; ADDRESS_SIZE] {
         [(self.0 >> 32) as u8, (self.0 >> 24) as u8, (self.0 >> 16) as u8, (self.0 >> 8) as u8, self.0 as u8]
     }
 
@@ -48,8 +48,8 @@ impl ToString for Address {
     fn to_string(&self) -> String {
         let mut v = self.0 << 24;
         let mut s = String::new();
-        s.reserve(10);
-        for _ in 0..10 {
+        s.reserve(ADDRESS_SIZE * 2);
+        for _ in 0..(ADDRESS_SIZE * 2) {
             s.push(HEX_CHARS[(v >> 60) as usize] as char);
             v <<= 4;
         }
@@ -79,14 +79,14 @@ impl Hash for Address {
     }
 }
 
-impl From<&[u8; 5]> for Address {
+impl From<&[u8; ADDRESS_SIZE]> for Address {
     #[inline(always)]
     fn from(b: &[u8; 5]) -> Address {
         Address((b[0] as u64) << 32 | (b[1] as u64) << 24 | (b[2] as u64) << 16 | (b[3] as u64) << 8 | b[4] as u64)
     }
 }
 
-impl From<[u8; 5]> for Address {
+impl From<[u8; ADDRESS_SIZE]> for Address {
     #[inline(always)]
     fn from(b: [u8; 5]) -> Address {
         Self::from(&b)

network-hypervisor/src/vl1/buffer.rs

@@ -207,20 +207,28 @@ impl<const L: usize> Buffer<L> {
         }
     }
 
-    /// Get a structure at position 0.
+    /// Get a structure at a given position in the buffer.
     #[inline(always)]
-    pub fn header<H: RawObject>(&self) -> &H {
-        debug_assert!(size_of::<H>() <= L);
-        debug_assert!(size_of::<H>() <= self.0);
-        unsafe { &*self.1.as_ptr().cast::<H>() }
+    pub fn struct_at<T: RawObject>(&self, ptr: usize) -> std::io::Result<&T> {
+        if (i + size_of::<T>()) <= self.0 {
+            unsafe {
+                Ok(&*self.1.as_ptr().cast::<u8>().offset(ptr as isize).cast::<T>())
+            }
+        } else {
+            std::io::Result::Err(std::io::Error::new(std::io::ErrorKind::UnexpectedEof, OVERFLOW_ERR_MSG))
+        }
     }
 
-    /// Get a structure at position 0 (mutable).
+    /// Get a structure at a given position in the buffer.
     #[inline(always)]
-    pub fn header_mut<H: RawObject>(&mut self) -> &mut H {
-        debug_assert!(size_of::<H>() <= L);
-        debug_assert!(size_of::<H>() <= self.0);
-        unsafe { &mut *self.1.as_mut_ptr().cast::<H>() }
+    pub fn struct_mut_at<T: RawObject>(&mut self, ptr: usize) -> std::io::Result<&mut T> {
+        if (i + size_of::<T>()) <= self.0 {
+            unsafe {
+                Ok(&mut *self.1.as_mut_ptr().cast::<u8>().offset(ptr as isize).cast::<T>())
+            }
+        } else {
+            std::io::Result::Err(std::io::Error::new(std::io::ErrorKind::UnexpectedEof, OVERFLOW_ERR_MSG))
+        }
     }
 
     /// Get a structure at a given position in the buffer and advance the cursor.

network-hypervisor/src/vl1/constants.rs

@@ -1,6 +1,9 @@
 /// Length of an address in bytes.
 pub const ADDRESS_SIZE: usize = 5;
 
+/// Prefix indicating reserved addresses (that can't actually be addresses).
+pub const ADDRESS_RESERVED_PREFIX: u8 = 0xff;
+
 /// Size of packet header that lies outside the encryption envelope.
 pub const PACKET_HEADER_SIZE: usize = 27;
 
@@ -19,6 +22,9 @@ pub const PACKET_SIZE_MIN: usize = PACKET_HEADER_SIZE + 1;
 /// Maximum size of an entire packet.
 pub const PACKET_SIZE_MAX: usize = PACKET_HEADER_SIZE + PACKET_PAYLOAD_SIZE_MAX;
 
+/// Index of destination in both fragment and full packet headers.
+pub const PACKET_DESTINATION_INDEX: usize = 8;
+
 /// Mask to select cipher from header flags field.
 pub const HEADER_FLAGS_FIELD_MASK_CIPHER: u8 = 0x30;
 
@@ -48,9 +54,14 @@ pub const FRAGMENT_SIZE_MIN: usize = 16;
 /// Maximum allowed number of fragments.
 pub const FRAGMENT_COUNT_MAX: usize = 16;
 
-/// Maximum number of fragmented packets in flight from a peer.
-/// Usually there should only be one at a time, so this is overkill.
-pub const PEER_DEFRAGMENT_MAX_PACKETS_IN_FLIGHT: usize = 4;
+/// Index of packet fragment indicator byte to detect fragments.
+pub const FRAGMENT_INDICATOR_INDEX: usize = 13;
+
+/// Byte found at FRAGMENT_INDICATOR_INDEX to indicate a fragment.
+pub const FRAGMENT_INDICATOR: u8 = 0xff;
+
+/// Maximum number of inbound fragments to handle at once per path.
+pub const FRAGMENT_MAX_PER_PATH: usize = 64;
 
 /// Verb (inner) flag indicating that the packet's payload (after the verb) is LZ4 compressed.
 pub const VERB_FLAG_COMPRESSED: u8 = 0x80;
@@ -58,11 +69,8 @@ pub const VERB_FLAG_COMPRESSED: u8 = 0x80;
 /// Maximum number of packet hops allowed by the protocol.
 pub const PROTOCOL_MAX_HOPS: usize = 7;
 
-/// Index of packet fragment indicator byte to detect fragments.
-pub const FRAGMENT_INDICATOR_INDEX: usize = 13;
+/// Frequency for WHOIS retries
+pub const WHOIS_RETRY_INTERVAL: i64 = 1000;
 
-/// Byte found at FRAGMENT_INDICATOR_INDEX to indicate a fragment.
-pub const FRAGMENT_INDICATOR: u8 = 0xff;
-
-/// Prefix indicating reserved addresses (that can't actually be addresses).
-pub const ADDRESS_RESERVED_PREFIX: u8 = 0xff;
+/// Maximum number of WHOIS retries
+pub const WHOIS_RETRY_MAX: u16 = 3;

network-hypervisor/src/vl1/fragmentedpacket.rs

@@ -0,0 +1,57 @@
+use std::sync::Arc;
+
+use crate::vl1::node::PacketBuffer;
+use crate::vl1::constants::FRAGMENT_COUNT_MAX;
+use crate::vl1::Path;
+use crate::vl1::protocol::PacketID;
+
+pub struct FragmentedPacket {
+    pub id: PacketID,
+    pub ts_ticks: i64,
+    frags: [Option<PacketBuffer>; FRAGMENT_COUNT_MAX],
+    have: u8,
+    expecting: u8,
+}
+
+impl Default for FragmentedPacket {
+    fn default() -> Self {
+        Self {
+            id: 0,
+            ts_ticks: -1,
+            frags: [None; FRAGMENT_COUNT_MAX],
+            have: 0,
+            expecting: 0,
+        }
+    }
+}
+
+impl FragmentedPacket {
+    /// Reset this fragmented packet for re-use.
+    #[inline(always)]
+    pub fn reset(&mut self) {
+        self.id = 0;
+        self.ts_ticks = -1;
+        self.frags.fill(None);
+        self.have = 0;
+        self.expecting = 0;
+    }
+
+    /// Initialize for a new packet.
+    #[inline(always)]
+    pub fn init(&mut self, id: PacketID, ts_ticks: i64) {
+        self.id = id;
+        self.ts_ticks = ts_ticks;
+    }
+
+    /// Add a fragment to this fragment set and return true if the packet appears complete.
+    #[inline(always)]
+    pub fn add(&mut self, frag: PacketBuffer, no: u8, expecting: u8) -> bool {
+        if self.frags[no].replace(frag).is_none() {
+            self.have = self.have.wrapping_add(1);
+            self.expecting |= expecting;
+            self.have == self.expecting
+        } else {
+            false
+        }
+    }
+}

network-hypervisor/src/vl1/identity.rs

@@ -23,6 +23,8 @@ const V1_BALLOON_SPACE_COST: usize = 16384;
 const V1_BALLOON_TIME_COST: usize = 3;
 const V1_BALLOON_DELTA: usize = 3;
 
+const V1_BALLOON_SALT: &'static [u8] = b"zt_id_v1";
+
 pub const IDENTITY_TYPE_0_SIGNATURE_SIZE: usize = ED25519_SIGNATURE_SIZE + 32;
 pub const IDENTITY_TYPE_1_SIGNATURE_SIZE: usize = P521_ECDSA_SIGNATURE_SIZE + ED25519_SIGNATURE_SIZE;
 
@@ -141,7 +143,7 @@ impl Identity {
         loop {
             // ECDSA is a randomized signature algorithm, so each signature will be different.
             let sig = p521_ecdsa.sign(&signing_buf).unwrap();
-            let bh = balloon::hash::<{ V1_BALLOON_SPACE_COST }, { V1_BALLOON_TIME_COST }, { V1_BALLOON_DELTA }>(&sig, b"zt_id_v1");
+            let bh = balloon::hash::<{ V1_BALLOON_SPACE_COST }, { V1_BALLOON_TIME_COST }, { V1_BALLOON_DELTA }>(&sig, V1_BALLOON_SALT);
             if bh[0] < 7 {
                 let addr = Address::from_bytes(&bh[59..64]).unwrap();
                 if addr.is_valid() {
@@ -229,7 +231,7 @@ impl Identity {
                 signing_buf[(C25519_PUBLIC_KEY_SIZE + ED25519_PUBLIC_KEY_SIZE)..(C25519_PUBLIC_KEY_SIZE + ED25519_PUBLIC_KEY_SIZE + P521_PUBLIC_KEY_SIZE)].copy_from_slice((*p521).0.public_key_bytes());
                 signing_buf[(C25519_PUBLIC_KEY_SIZE + ED25519_PUBLIC_KEY_SIZE + P521_PUBLIC_KEY_SIZE)..(C25519_PUBLIC_KEY_SIZE + ED25519_PUBLIC_KEY_SIZE + P521_PUBLIC_KEY_SIZE + P521_PUBLIC_KEY_SIZE)].copy_from_slice((*p521).1.public_key_bytes());
                 if (*p521).1.verify(&signing_buf, &(*p521).2) {
-                    let bh = balloon::hash::<{ V1_BALLOON_SPACE_COST }, { V1_BALLOON_TIME_COST }, { V1_BALLOON_DELTA }>(&(*p521).2, b"zt_id_v1");
+                    let bh = balloon::hash::<{ V1_BALLOON_SPACE_COST }, { V1_BALLOON_TIME_COST }, { V1_BALLOON_DELTA }>(&(*p521).2, V1_BALLOON_SALT);
                     (bh[0] < 7) && bh.eq(&(*p521).3) && Address::from_bytes(&bh[59..64]).unwrap().eq(&self.address)
                 } else {
                     false

network-hypervisor/src/vl1/inetaddress.rs

@@ -238,24 +238,6 @@ impl InetAddress {
         }
     }
 
-    #[inline(always)]
-    pub(crate) fn local_lookup_key(&self) -> u128 {
-        unsafe {
-            match self.sa.sa_family as u8 {
-                AF_INET => {
-                    ((self.sin.sin_addr.s_addr as u64).wrapping_shl(16) | self.sin.sin_port as u64) as u128
-                }
-                AF_INET6 => {
-                    let mut tmp: [u64; 2] = MaybeUninit::uninit().assume_init();
-                    copy_nonoverlapping((&self.sin6.sin6_addr as *const in6_addr).cast::<u8>(), tmp.as_mut_ptr().cast::<u8>(), 16);
-                    tmp[1] = tmp[1].wrapping_add((self.sin6.sin6_port as u64) ^ crate::crypto::salt64());
-                    (*tmp.as_ptr().cast::<u128>()).wrapping_mul(0x0fc94e3bf4e9ab32866458cd56f5e605)
-                }
-                _ => 0
-            }
-        }
-    }
-
     /// Get this IP address's scope as per RFC documents and what is advertised via BGP.
     pub fn scope(&self) -> IpScope {
         unsafe {
@@ -488,6 +470,7 @@ impl FromStr for InetAddress {
 }
 
 impl PartialEq for InetAddress {
+    #[inline(always)]
     fn eq(&self, other: &Self) -> bool {
         unsafe {
             if self.sa.sa_family == other.sa.sa_family {

network-hypervisor/src/vl1/mod.rs

@@ -3,6 +3,11 @@ pub(crate) mod buffer;
 pub(crate) mod node;
 pub(crate) mod path;
 pub(crate) mod peer;
+pub(crate) mod dictionary;
+pub(crate) mod address;
+pub(crate) mod mac;
+pub(crate) mod fragmentedpacket;
+mod(crate) mod whois;
 
 pub mod constants;
 pub mod identity;
@@ -10,10 +15,6 @@ pub mod inetaddress;
 pub mod endpoint;
 pub mod locator;
 
-mod dictionary;
-mod address;
-mod mac;
-
 pub use address::Address;
 pub use mac::MAC;
 pub use identity::Identity;

network-hypervisor/src/vl1/node.rs

@@ -1,20 +1,23 @@
-use std::sync::Arc;
-use std::str::FromStr;
-use std::time::Duration;
-use std::marker::PhantomData;
 use std::hash::Hash;
+use std::marker::PhantomData;
+use std::str::FromStr;
+use std::sync::Arc;
+use std::time::Duration;
+
+use dashmap::DashMap;
+use parking_lot::Mutex;
 
 use crate::crypto::random::SecureRandom;
 use crate::error::InvalidParameterError;
+use crate::util::gate::IntervalGate;
 use crate::util::pool::{Pool, Pooled};
-use crate::vl1::{Address, Identity, Endpoint, Locator};
+use crate::vl1::{Address, Endpoint, Identity, Locator};
 use crate::vl1::buffer::Buffer;
-use crate::vl1::constants::{PACKET_SIZE_MAX, FRAGMENT_COUNT_MAX};
+use crate::vl1::constants::PACKET_SIZE_MAX;
 use crate::vl1::path::Path;
 use crate::vl1::peer::Peer;
-
-use parking_lot::Mutex;
-use dashmap::DashMap;
+use crate::vl1::protocol::{FragmentHeader, is_fragment, PacketHeader, PacketID};
+use crate::vl1::whois::Whois;
 
 /// Standard packet buffer type including pool container.
 pub type PacketBuffer = Pooled<Buffer<{ PACKET_SIZE_MAX }>>;
@@ -96,12 +99,18 @@ pub trait VL1CallerInterface {
     fn time_clock(&self) -> i64;
 }
 
+#[derive(Default)]
+struct BackgroundTaskIntervals {
+    whois: IntervalGate<{ Whois::INTERVAL }>,
+}
+
 pub struct Node {
     identity: Identity,
+    intervals: Mutex<BackgroundTaskIntervals>,
     locator: Mutex<Option<Locator>>,
-    paths_by_inaddr: DashMap<u128, Arc<Path>>,
+    paths: DashMap<Endpoint, Arc<Path>>,
     peers: DashMap<Address, Arc<Peer>>,
-    peer_vec: Mutex<Vec<Arc<Peer>>>, // for rapid iteration through all peers
+    whois: Whois,
     buffer_pool: Pool<Buffer<{ PACKET_SIZE_MAX }>>,
     secure_prng: SecureRandom,
 }
@@ -136,10 +145,11 @@ impl Node {
 
         Ok(Self {
             identity: id,
+            intervals: Mutex::new(BackgroundTaskIntervals::default()),
             locator: Mutex::new(None),
-            paths_by_inaddr: DashMap::new(),
+            paths: DashMap::new(),
             peers: DashMap::new(),
-            peer_vec: Mutex::new(Vec::new()),
+            whois: Whois::new(),
             buffer_pool: Pool::new(64),
             secure_prng: SecureRandom::get(),
         })
@@ -164,15 +174,73 @@ impl Node {
         self.buffer_pool.get()
     }
 
+    /// Get a peer by address.
+    #[inline(always)]
+    pub fn peer(&self, a: Address) -> Option<Arc<Peer>> {
+        self.peers.get(&a).map(|peer| peer.clone() )
+    }
+
+    /// Get all peers currently in the peer cache.
+    pub fn peers(&self) -> Vec<Arc<Peer>> {
+        let mut v: Vec<Arc<Peer>> = Vec::new();
+        v.reserve(self.peers.len());
+        for p in self.peers.iter() {
+            v.push(p.value().clone());
+        }
+        v
+    }
+
     /// Run background tasks and return desired delay until next call in milliseconds.
     /// This should only be called once at a time. It technically won't hurt anything to
     /// call concurrently but it will waste CPU cycles.
     pub fn do_background_tasks<CI: VL1CallerInterface>(&self, ci: &CI) -> Duration {
+        let intervals = self.intervals.lock();
+        let tt = ci.time_ticks();
+
+        if intervals.whois.gate(tt) {
+            self.whois.on_interval(self, ci, tt);
+        }
+
         Duration::from_millis(1000)
     }
 
     /// Called when a packet is received on the physical wire.
-    pub fn wire_receive<CI: VL1CallerInterface>(&self, ci: &CI, endpoint: &Endpoint, local_socket: i64, local_interface: i64, data: PacketBuffer) {
+    pub fn wire_receive<CI: VL1CallerInterface>(&self, ci: &CI, source_endpoint: &Endpoint, source_local_socket: i64, source_local_interface: i64, mut data: PacketBuffer) {
+        let _ = data.struct_mut_at::<FragmentHeader>(0).map(|fragment_header| {
+            // NOTE: destination address is located at the same index in both the fragment
+            // header and the full packet header, allowing us to make this decision once.
+            let dest = Address::from(&fragment_header.dest);
+            if dest == self.identity.address() {
+                // Packet or fragment is addressed to this node.
+
+                let path = self.path(source_endpoint, source_local_socket, source_local_interface);
+                if fragment_header.is_fragment() {
+                } else {
+                    data.struct_mut_at::<PacketHeader>(0).map(|header| {
+                        let source = Address::from(&header.src);
+
+                        if header.is_fragmented() {
+                        } else {
+                        }
+                    });
+                }
+
+            } else {
+                // Packet or fragment is addressed to another node.
+            }
+        });
+    }
+
+    /// Get the canonical Path object for a given endpoint and local socket information.
+    /// This is a canonicalizing function that returns a unique path object for every tuple
+    /// of endpoint, local socket, and local interface.
+    pub(crate) fn path(&self, ep: &Endpoint, local_socket: i64, local_interface: i64) -> Arc<Path> {
+        self.paths.get(ep).map_or_else(|| {
+            let p = Arc::new(Path::new(ep.clone(), local_socket, local_interface));
+            self.paths.insert(ep.clone(), p.clone()).unwrap_or(p) // if another thread added one, return that instead
+        }, |path| {
+            path.clone()
+        })
     }
 }
 

network-hypervisor/src/vl1/path.rs

@@ -1,13 +1,25 @@
 use std::sync::atomic::{AtomicI64, Ordering};
 
 use crate::vl1::Endpoint;
+use crate::vl1::constants::FRAGMENT_COUNT_MAX;
+use crate::vl1::fragmentedpacket::FragmentedPacket;
+use crate::vl1::protocol::{FragmentHeader, PacketID};
+use crate::vl1::node::PacketBuffer;
+
+use parking_lot::Mutex;
+
+struct RxState {
+    last_receive_time_ticks: i64,
+    fragmented_packet_count: usize,
+    fragmented_packets: [FragmentedPacket; FRAGMENT_COUNT_MAX],
+}
 
 pub struct Path {
     pub(crate) endpoint: Endpoint,
     pub(crate) local_socket: i64,
     pub(crate) local_interface: i64,
     last_send_time_ticks: AtomicI64,
-    last_receive_time_ticks: AtomicI64,
+    rxs: Mutex<RxState>,
 }
 
 impl Path {
@@ -18,7 +30,11 @@ impl Path {
             local_socket,
             local_interface,
             last_send_time_ticks: AtomicI64::new(0),
-            last_receive_time_ticks: AtomicI64::new(0),
+            rxs: Mutex::new(RxState {
+                last_receive_time_ticks: 0,
+                fragmented_packet_count: 0,
+                fragmented_packets: [FragmentedPacket::default(); FRAGMENT_COUNT_MAX]
+            })
         }
     }
 
@@ -29,7 +45,48 @@ impl Path {
 
     #[inline(always)]
     pub fn send_receive_time_ticks(&self) -> i64 {
-        self.last_receive_time_ticks.load(Ordering::Relaxed)
+        self.rxs.lock().last_receive_time_ticks
+    }
+
+    #[inline(always)]
+    pub(crate) fn receive_fragment<F: FnOnce(&mut FragmentedPacket)>(&self, packet_id: PacketID, fragment_no: u8, fragment_expecting_count: u8, packet: PacketBuffer, time_ticks: i64, assembled_packet_handler: F) {
+        if fragment_no < FRAGMENT_COUNT_MAX as u8 {
+            let mut rxs = self.rxs.lock();
+            rxs.last_receive_time_ticks = time_ticks;
+
+            let mut fpcnt = rxs.fragmented_packet_count;
+            let mut fidx = 0;
+            while fpcnt > 0 {
+                let mut f = &mut rxs.fragmented_packets[fidx];
+                if f.id == packet_id {
+                    if f.add(packet, fragment_no, fragment_expecting_count) {
+                        assembled_packet_handler(f);
+                        f.reset();
+                        rxs.fragmented_packet_count = rxs.fragmented_packet_count.wrapping_sub(1);
+                    }
+                    return;
+                } else if f.ts_ticks >= 0 {
+                    fpcnt = fpcnt.wrapping_sub(1);
+                }
+                fidx = fidx.wrapping_add(1);
+            }
+
+            let mut oldest_ts = rxs.fragmented_packets[0].ts_ticks;
+            let mut oldest_idx = 0;
+            if oldest_ts >= 0 {
+                for fidx in 1..FRAGMENT_COUNT_MAX {
+                    let ts = rxs.fragmented_packets[fidx].ts_ticks;
+                    if ts < oldest_ts {
+                        oldest_ts = ts;
+                        oldest_idx = fidx;
+                    }
+                }
+            }
+
+            let mut f = &mut rxs.fragmented_packets[oldest_idx];
+            f.init(packet_id, time_ticks);
+            let _ = f.add(packet, fragment_no, fragment_expecting_count);
+        }
     }
 }
 

network-hypervisor/src/vl1/peer.rs

@@ -1,41 +1,47 @@
 use std::sync::Arc;
 use std::sync::atomic::{AtomicI64, AtomicU64, AtomicU8};
 
-use crate::vl1::protocol::PacketID;
-use crate::vl1::node::PacketBuffer;
-use crate::vl1::constants::{FRAGMENT_COUNT_MAX, PEER_DEFRAGMENT_MAX_PACKETS_IN_FLIGHT};
 use crate::vl1::{Identity, Path};
+use crate::vl1::fragmentedpacket::FragmentedPacket;
+use crate::vl1::protocol::{PacketID, PacketHeader};
+use crate::vl1::node::{VL1CallerInterface, PacketBuffer, Node};
 
 use parking_lot::Mutex;
 
-struct FragmentedPacket {
-    pub id: PacketID,
-    pub frag: [Option<PacketBuffer>; FRAGMENT_COUNT_MAX],
+const MAX_PATHS: usize = 16;
+
+struct TxState {
+    packet_iv_counter: u64,
+    last_send_time_ticks: i64,
+    paths: [Arc<Path>; MAX_PATHS],
 }
 
+struct RxState {
+    last_receive_time_ticks: i64,
+    remote_version: [u8; 4],
+    remote_protocol_version: u8,
+}
+
+/// A remote peer known to this node.
+/// Sending-related and receiving-related fields are locked separately since concurrent
+/// send/receive is not uncommon.
 pub struct Peer {
-    // This peer's identity.
     identity: Identity,
 
-    // Primary static secret resulting from key agreement with identity.
+    // Static shared secret computed from agreement with identity.
     identity_static_secret: [u8; 48],
 
-    // Outgoing packet IV counter used to generate packet IDs to this peer.
-    packet_iv_counter: AtomicU64,
+    // State used primarily when sending to this peer.
+    txs: Mutex<TxState>,
 
-    // Paths sorted in ascending order of quality / preference.
-    paths: Mutex<Vec<Arc<Path>>>,
-
-    // Incoming fragmented packet defragment buffer.
-    fragmented_packets: Mutex<[FragmentedPacket; PEER_DEFRAGMENT_MAX_PACKETS_IN_FLIGHT]>,
-
-    // Last send and receive time in millisecond ticks (not wall clock).
-    last_send_time_ticks: AtomicI64,
-    last_receive_time_ticks: AtomicI64,
-
-    // Most recent remote version (most to least significant bytes: major, minor, revision, build)
-    remote_version: AtomicU64,
-
-    // Most recent remote protocol version
-    remote_protocol_version: AtomicU8,
+    // State used primarily when receiving from this peer.
+    rxs: Mutex<RxState>,
+}
+
+impl Peer {
+    pub(crate) fn receive_from_singular<CI: VL1CallerInterface>(&self, node: &Node, ci: &CI, header: &PacketHeader, packet: &PacketBuffer) {
+    }
+
+    pub(crate) fn receive_from_fragmented<CI: VL1CallerInterface>(&self, node: &Node, ci: CI, header: &PacketHeader, packet: &FragmentedPacket) {
+    }
 }

network-hypervisor/src/vl1/protocol.rs

@@ -54,12 +54,6 @@ impl PacketHeader {
         (self.flags_cipher_hops & HEADER_FLAG_FRAGMENTED) != 0
     }
 
-    /// If true, this packet is actually a fragment and its header should be interpreted as a FragmentHeader instead.
-    #[inline(always)]
-    pub fn is_fragment(&self) -> bool {
-        self.src[0] == FRAGMENT_INDICATOR
-    }
-
     #[inline(always)]
     pub fn destination(&self) -> Address {
         Address::from(&self.dest)
@@ -89,6 +83,11 @@ pub struct FragmentHeader {
 unsafe impl crate::vl1::buffer::RawObject for FragmentHeader {}
 
 impl FragmentHeader {
+    #[inline(always)]
+    pub fn is_fragment(&self) -> bool {
+        self.fragment_indicator == FRAGMENT_INDICATOR
+    }
+
     #[inline(always)]
     pub fn total_fragments(&self) -> u8 {
         self.total_and_fragment_no >> 4
@@ -104,6 +103,12 @@ impl FragmentHeader {
         self.reserved_hops & HEADER_FLAGS_FIELD_MASK_HOPS
     }
 
+    #[inline(always)]
+    pub fn increment_hops(&mut self) {
+        let f = self.reserved_hops;
+        self.reserved_hops = (f & HEADER_FLAGS_FIELD_MASK_HOPS.not()) | ((f + 1) & HEADER_FLAGS_FIELD_MASK_HOPS);
+    }
+
     #[inline(always)]
     pub fn destination(&self) -> Address {
         Address::from(&self.dest)

network-hypervisor/src/vl1/whois.rs

@@ -0,0 +1,75 @@
+use std::collections::HashMap;
+
+use crate::vl1::Address;
+use crate::vl1::fragmentedpacket::FragmentedPacket;
+use crate::vl1::node::{VL1CallerInterface, Node, PacketBuffer};
+use crate::util::gate::IntervalGate;
+
+use parking_lot::Mutex;
+use crate::vl1::constants::{WHOIS_RETRY_INTERVAL, WHOIS_RETRY_MAX};
+
+pub enum QueuedPacket {
+    Singular(PacketBuffer),
+    Fragmented(FragmentedPacket)
+}
+
+struct WhoisQueueItem {
+    retry_gate: IntervalGate<{ WHOIS_RETRY_INTERVAL }>,
+    retry_count: u16,
+    packet_queue: Vec<QueuedPacket>
+}
+
+pub struct Whois {
+    queue: Mutex<HashMap<Address, WhoisQueueItem>>
+}
+
+impl Whois {
+    pub const INTERVAL: i64 = WHOIS_RETRY_INTERVAL;
+
+    pub fn new() -> Self {
+        Self {
+            queue: Mutex::new(HashMap::new())
+        }
+    }
+
+    pub fn query<CI: VL1CallerInterface>(&self, node: &Node, ci: &CI, target: Address, packet: Option<QueuedPacket>) {
+        let mut q = self.queue.lock();
+        if q.get_mut(&target).map_or_else(|| {
+            q.insert(target, WhoisQueueItem {
+                retry_gate: IntervalGate::new(ci.time_ticks()),
+                retry_count: 1,
+                packet_queue: packet.map_or_else(|| Vec::new(), |p| vec![p]),
+            });
+            true
+        }, |qi| {
+            let g = qi.retry_gate(ci.time_ticks());
+            qi.retry_count += g as u16;
+            let _ = packet.map(|p| qi.packet_queue.push(p));
+            g
+        }) {
+            self.send_whois(node, ci, &[target]);
+        }
+    }
+
+    pub fn on_interval<CI: VL1CallerInterface>(&self, node: &Node, ci: &CI, time_ticks: i64) {
+        let mut targets: Vec<Address> = Vec::new();
+        self.queue.lock().retain(|target, qi| {
+            if qi.retry_count < WHOIS_RETRY_MAX {
+                if qi.retry_gate.gate(time_ticks) {
+                    qi.retry_count += 1;
+                    targets.push(*target);
+                }
+                true
+            } else {
+                false
+            }
+        });
+        if !targets.is_empty() {
+            self.send_whois(node, ci, targets.as_slice());
+        }
+    }
+
+    fn send_whois<CI: VL1CallerInterface>(&self, node: &Node, ci: &CI, targets: &[Address]) {
+        todo!()
+    }
+}