Drop prepends in BGP paths since it doesn't change our results

diff --git a/src/bgp_client.rs b/src/bgp_client.rs
index 04be1360c930cc6d01f65bd57f5f44340c4777a9..10880a6dc835c61965f17d3460eabc6597c7aa24 100644 (file)
--- a/src/bgp_client.rs
+++ b/src/bgp_client.rs
@@ -22,8 +22,10 @@ use futures::sync::mpsc;
 use crate::printer::{Printer, Stat};
 use crate::timeout_stream::TimeoutStream;
 
+const PATH_SUFFIX_LEN: usize = 3;
 struct Route {
-       path: Vec<u32>,
+       path_suffix: [u32; PATH_SUFFIX_LEN],
+       path_len: u32,
        pref: u32,
        med: u32,
 }
@@ -180,20 +182,27 @@ impl BGPClient {
 
                path_vecs.sort_unstable_by(|path_a, path_b| {
                        path_a.pref.cmp(&path_b.pref)
-                               .then(path_b.path.len().cmp(&path_a.path.len()))
+                               .then(path_b.path_len.cmp(&path_a.path_len))
                                .then(path_b.med.cmp(&path_a.med))
                });
 
                let primary_route = path_vecs.pop().unwrap();
-               'asn_candidates: for asn in primary_route.path.iter().rev() {
+               'asn_candidates: for asn in primary_route.path_suffix.iter().rev() {
+                       if *asn == 0 { continue 'asn_candidates; }
                        for secondary_route in path_vecs.iter() {
-                               if !secondary_route.path.contains(asn) {
+                               if !secondary_route.path_suffix.contains(asn) {
                                        continue 'asn_candidates;
                                }
                        }
                        return *asn;
                }
-               *primary_route.path.last().unwrap_or(&0)
+
+               for asn in primary_route.path_suffix.iter().rev() {
+                       if *asn != 0 {
+                               return *asn;
+                       }
+               }
+               0
        }
 
        pub fn disconnect(&self) {
@@ -215,15 +224,25 @@ impl BGPClient {
                        }
                }
                if let Some(mut aspath) = as4_path.or(as_path) {
-                       let mut path = Vec::new();
+                       let mut pathvec = Vec::new();
                        for seg in aspath.segments.drain(..) {
                                match seg {
-                                       Segment::AS_SEQUENCE(mut asn) => path.append(&mut asn),
+                                       Segment::AS_SEQUENCE(mut asn) => pathvec.append(&mut asn),
                                        Segment::AS_SET(_) => {}, // Ignore sets for now, they're not that common anyway
                                }
                        }
+                       let path_len = pathvec.len() as u32;
+                       pathvec.dedup_by(|a, b| (*a).eq(b)); // Drop prepends, cause we don't care in this case
+
+                       let mut path_suffix = [0; PATH_SUFFIX_LEN];
+                       for (idx, asn) in pathvec.iter().rev().enumerate() {
+                               path_suffix[PATH_SUFFIX_LEN - idx - 1] = *asn;
+                               if idx == PATH_SUFFIX_LEN - 1 { break; }
+                       }
+
                        return Some(Route {
-                               path: path.clone(),
+                               path_suffix,
+                               path_len,
                                pref,
                                med,
                        })