bgp, ldp, ospfv3: optimize decoding of IP prefixes

This update makes some simple tweaks to avoid allocating memory when decoding IP prefixes from a byte stream. During testing with 1 million BGP routes, the daemon used to spend about 2.6% of its time decoding prefixes from BGP messages, according to flamegraphs. Now it's down to just 0.2%. Big win! Signed-off-by: Renato Westphal <[email protected]>
holo-routing · Feb 27, 2024 · cac45c9 · cac45c9
1 parent 0a92a02
commit cac45c9
Show file tree

Hide file tree

Showing 4 changed files with 34 additions and 45 deletions.
diff --git a/holo-bgp/src/packet/message.rs b/holo-bgp/src/packet/message.rs
@@ -994,9 +994,9 @@ pub(crate) fn decode_ipv4_prefix(
     }
 
     // Parse prefix address (variable length).
-    let mut prefix_bytes = vec![0; plen_wire];
-    buf.copy_to_slice(&mut prefix_bytes);
-    let prefix = Ipv4Addr::from_slice(&prefix_bytes);
+    let mut prefix_bytes = [0; Ipv4Addr::LENGTH];
+    buf.copy_to_slice(&mut prefix_bytes[..plen_wire]);
+    let prefix = Ipv4Addr::from(prefix_bytes);
     let prefix = Ipv4Network::new(prefix, plen)
         .map(|prefix| prefix.apply_mask())
         .map_err(|_| UpdateMessageError::InvalidNetworkField)?;
@@ -1023,9 +1023,9 @@ pub(crate) fn decode_ipv6_prefix(
     }
 
     // Parse prefix address (variable length).
-    let mut prefix_bytes = vec![0; plen_wire];
-    buf.copy_to_slice(&mut prefix_bytes);
-    let prefix = Ipv6Addr::from_slice(&prefix_bytes);
+    let mut prefix_bytes = [0; Ipv6Addr::LENGTH];
+    buf.copy_to_slice(&mut prefix_bytes[..plen_wire]);
+    let prefix = Ipv6Addr::from(prefix_bytes);
     let prefix = Ipv6Network::new(prefix, plen)
         .map(|prefix| prefix.apply_mask())
         .map_err(|_| UpdateMessageError::InvalidNetworkField)?;

diff --git a/holo-ldp/src/packet/messages/label.rs b/holo-ldp/src/packet/messages/label.rs
@@ -4,11 +4,12 @@
 // SPDX-License-Identifier: MIT
 //
 
-use std::net::IpAddr;
+use std::net::{Ipv4Addr, Ipv6Addr};
 
 use bytes::{Buf, BufMut, Bytes, BytesMut};
 use holo_utils::ip::{
-    AddressFamily, IpAddrExt, IpNetworkExt, Ipv4NetworkExt, Ipv6NetworkExt,
+    AddressFamily, IpAddrExt, IpNetworkExt, Ipv4AddrExt, Ipv4NetworkExt,
+    Ipv6AddrExt, Ipv6NetworkExt,
 };
 use holo_utils::mpls::Label;
 use ipnetwork::{IpNetwork, Ipv4Network, Ipv6Network};
@@ -478,10 +479,19 @@ impl FecElem {
                 }
 
                 // Parse prefix.
-                let mut prefix_bytes = vec![0; plen_wire];
-                buf.copy_to_slice(&mut prefix_bytes);
+                let prefix = match af {
+                    AddressFamily::Ipv4 => {
+                        let mut prefix_bytes = [0; Ipv4Addr::LENGTH];
+                        buf.copy_to_slice(&mut prefix_bytes[..plen_wire]);
+                        Ipv4Addr::from(prefix_bytes).into()
+                    }
+                    AddressFamily::Ipv6 => {
+                        let mut prefix_bytes = [0; Ipv6Addr::LENGTH];
+                        buf.copy_to_slice(&mut prefix_bytes[..plen_wire]);
+                        Ipv6Addr::from(prefix_bytes).into()
+                    }
+                };
                 *tlv_rlen -= plen_wire as u16;
-                let prefix = IpAddr::from_slice(af, &prefix_bytes);
                 IpNetwork::new(prefix, plen)
                     .map(|prefix| FecElem::Prefix(prefix.apply_mask()))
                     .map_err(|_| DecodeError::InvalidTlvValue(tlvi.clone()))

diff --git a/holo-ospf/src/ospfv3/packet/lsa.rs b/holo-ospf/src/ospfv3/packet/lsa.rs
@@ -12,7 +12,7 @@ use bytes::{Buf, BufMut, Bytes, BytesMut};
 use derive_new::new;
 use enum_as_inner::EnumAsInner;
 use holo_utils::bytes::{BytesExt, BytesMutExt};
-use holo_utils::ip::{AddressFamily, IpAddrExt};
+use holo_utils::ip::{AddressFamily, IpAddrExt, Ipv4AddrExt, Ipv6AddrExt};
 use holo_utils::mpls::Label;
 use holo_utils::sr::{IgpAlgoType, Sid};
 use ipnetwork::IpNetwork;
@@ -2891,9 +2891,18 @@ fn decode_prefix(
     buf: &mut Bytes,
 ) -> DecodeResult<IpNetwork> {
     let plen_wire = prefix_wire_len(plen);
-    let mut prefix_bytes = vec![0; plen_wire];
-    buf.copy_to_slice(&mut prefix_bytes);
-    let prefix = IpAddr::from_slice(af, &prefix_bytes);
+    let prefix = match af {
+        AddressFamily::Ipv4 => {
+            let mut prefix_bytes = [0; Ipv4Addr::LENGTH];
+            buf.copy_to_slice(&mut prefix_bytes[..plen_wire]);
+            Ipv4Addr::from(prefix_bytes).into()
+        }
+        AddressFamily::Ipv6 => {
+            let mut prefix_bytes = [0; Ipv6Addr::LENGTH];
+            buf.copy_to_slice(&mut prefix_bytes[..plen_wire]);
+            Ipv6Addr::from(prefix_bytes).into()
+        }
+    };
     IpNetwork::new(prefix, plen).map_err(|_| DecodeError::InvalidIpPrefix)
 }
 

diff --git a/holo-utils/src/ip.rs b/holo-utils/src/ip.rs
@@ -34,9 +34,6 @@ pub trait IpAddrExt {
     // Returns vector of bytes that make up this address.
     fn bytes(&self) -> Vec<u8>;
 
-    // Creates an IpAddr from a slice of bytes.
-    fn from_slice(af: AddressFamily, bytes: &[u8]) -> IpAddr;
-
     // Returns true if this is an usable address.
     fn is_usable(&self) -> bool;
 
@@ -48,9 +45,6 @@ pub trait IpAddrExt {
 pub trait Ipv4AddrExt {
     const LENGTH: usize;
 
-    // Creates an Ipv4Addr from a slice of bytes.
-    fn from_slice(bytes: &[u8]) -> Ipv4Addr;
-
     // Returns true if this is an usable address.
     fn is_usable(&self) -> bool;
 }
@@ -59,9 +53,6 @@ pub trait Ipv4AddrExt {
 pub trait Ipv6AddrExt {
     const LENGTH: usize;
 
-    // Creates an Ip6Addr from a slice of bytes.
-    fn from_slice(bytes: &[u8]) -> Ipv6Addr;
-
     // Returns true if this is an usable address.
     fn is_usable(&self) -> bool;
 }
@@ -242,13 +233,6 @@ impl IpAddrExt for IpAddr {
         }
     }
 
-    fn from_slice(af: AddressFamily, bytes: &[u8]) -> IpAddr {
-        match af {
-            AddressFamily::Ipv4 => Ipv4Addr::from_slice(bytes).into(),
-            AddressFamily::Ipv6 => Ipv6Addr::from_slice(bytes).into(),
-        }
-    }
-
     fn is_usable(&self) -> bool {
         !(self.is_loopback() || self.is_multicast() || self.is_unspecified())
     }
@@ -283,13 +267,6 @@ impl IpAddrKind for IpAddr {
 impl Ipv4AddrExt for Ipv4Addr {
     const LENGTH: usize = 4;
 
-    fn from_slice(bytes: &[u8]) -> Ipv4Addr {
-        let mut bytes = bytes.to_vec();
-        bytes.resize(4, 0);
-        let bytes: [u8; 4] = bytes[..].try_into().unwrap();
-        Ipv4Addr::from(bytes)
-    }
-
     fn is_usable(&self) -> bool {
         !(self.is_loopback()
             || self.is_broadcast()
@@ -320,13 +297,6 @@ impl IpAddrKind for Ipv4Addr {
 impl Ipv6AddrExt for Ipv6Addr {
     const LENGTH: usize = 16;
 
-    fn from_slice(bytes: &[u8]) -> Ipv6Addr {
-        let mut bytes = bytes.to_vec();
-        bytes.resize(16, 0);
-        let bytes: [u8; 16] = bytes[..].try_into().unwrap();
-        Ipv6Addr::from(bytes)
-    }
-
     fn is_usable(&self) -> bool {
         !(self.is_loopback() || self.is_multicast() || self.is_unspecified())
     }