major: rework the route watcher

4 files changed, 117 insertions, 101 deletions

diff --git a/.fpm b/.fpm
index b0cf29a..c620755 100644
--- a/.fpm
+++ b/.fpm
@@ -10,3 +10,4 @@
 frr-evpn-route-watcher/=/usr/lib/frr-evpn-route-watcher/
 frr-evpn-route-watcher.service=/etc/systemd/system/frr-evpn-route-watcher.service
 frr-evpn-route-watcher.timer=/etc/systemd/system/frr-evpn-route-watcher.timer
+frr-evpn-route-watcher.conf=/etc/iproute2/rt_protos.d/frr-evpn-route-watcher.conf
diff --git a/frr-evpn-route-watcher.conf b/frr-evpn-route-watcher.conf
new file mode 100644
index 0000000..e53963c
--- /dev/null
+++ b/frr-evpn-route-watcher.conf
@@ -0,0 +1,2 @@
+# Used for registering the routing protocol defined by frr-evpn-route-watcher
+199  frr-evpn-route-watcher
diff --git a/frr-evpn-route-watcher/task.py b/frr-evpn-route-watcher/task.py
index ce31d92..ab1a87e 100755
--- a/frr-evpn-route-watcher/task.py
+++ b/frr-evpn-route-watcher/task.py
@@ -2,114 +2,127 @@
 import json
 import ipaddress
 import subprocess
-import re
 
-def get_frr_vrfs():
-    """Gets the list of vrf VNIs configured in FRR"""
-    process = subprocess.run(["vtysh", "-c", "show vrf vni json"], capture_output=True)
-    return json.loads(process.stdout)["vrfs"]
+def vtysh(cmd):
+    print(f"@: vtysh -c {cmd}")
+    return subprocess.run([
+        "vtysh",
+        "-c",
+        cmd
+    ], capture_output=True).stdout
 
-def get_frr_evpn_info():
-    """Lists all the routes learned via evpn"""
-    process = subprocess.run(
-        ["vtysh", "-c", "show bgp l2vpn evpn json"], capture_output=True
-    )
-    return json.loads(process.stdout)
+def get_frr_vrfs():
+    """
+    gets the list of VNIs declared in the evpn config
+    """
+    print("I: Listing evpn VNIs")
+    show_evpn_vni = vtysh("sh evpn vni json")
+    return json.loads(show_evpn_vni)
+
+def get_frr_arp_cache(vni):
+    """
+    gets the list of atp-cache entries in the given VNI
+    """
+    print(f"I: Listing evpn arp-cache for VNI {vni}")
+    show_evpn_arp_cache = vtysh(f"sh evpn arp-cache vni {vni} json")
+    return json.loads(show_evpn_arp_cache)
+
+def get_current_routes():
+    """
+    gets the list of routes currently applied using frr-evpn-route-watcher
+    """
+    command = [
+        "ip",
+        "route",
+        "show",
+        "proto",
+        "frr-evpn-route-watcher"
+    ]
+    process4 = subprocess.run(command, capture_output=True)
+    process6 = subprocess.run(command + ["-6"], capture_output=True)
+
+    routes = process4.stdout.splitlines() + process6.stdout.splitlines()
+    out = {}
+
+    for route in routes:
+        # <ip> dev <vrf> scope link
+        parts = route.split(" ")
+        if len(parts) == 5:
+            valid = parts[1] == "dev" \
+                and parts[3] == "scope" \
+                and parts[4] == "link"
+            if valid:
+                ipraw = parts[0]
+                vrf = parts[2]
+                ip = ipaddress.ip_address(ipraw)
+                out[ip] = vrf
+                print(f"D: Found existing route for {ip}")
+    return out
 
 def add_route_vrf(ip, vrf):
-    """Add a route using the ip route command"""
-    subprocess.run(
-        ["ip", "route", "add", str(ip), "dev", vrf, "metric", "0"],
-    )
+    """
+    Add a route using the ip route command that points to a vrf interface
+    """
+    print(f"I: Adding route for {ip} -> {vrf}")
+    subprocess.run([
+            "ip",
+            "route",
+            "add",
+            str(ip),
+            "dev",
+            vrf,
+            "proto",
+            "frr-evpn-route-watcher"
+    ])
 
 def remove_route_vrf(ip):
+    """removes a route to a given ip"""
+    print(f"I: Removing route to {ip}")
     subprocess.run(["ip", "route", "del", str(ip)])
 
-def currently_routed(vrfs_names):
-    processfour = subprocess.run(["ip", "route"], capture_output=True, text=True).stdout.splitlines()
-    processsixe = subprocess.run(["ip", "-6", "route"], capture_output=True, text=True).stdout.splitlines()
-    processresults = processfour + processsixe
-    routed_ips = []
-    for route in processresults:
-        parts = route.split(" ")
-        if len(parts) == 6:
-            addr, dev, vrf, scope, link = (
-                parts[0],
-                parts[1],
-                parts[2],
-                parts[3],
-                parts[4],
-            )
-            addr = parse_ip(addr)
-            if (
-                addr != None
-                and dev == "dev"
-                and vrf in vrfs_names
-                and scope == "scope"
-                and link == "link"
-            ):
-                routed_ips.append(addr)
-    return routed_ips
-
-def parse_ip(str):
-    try:
-        return ipaddress.ip_network(str)
-    except ValueError:
-        return False
-
-def get_vrfs():
-    return {str(vrf["vni"]): vrf["vrf"] for vrf in get_frr_vrfs()}
-
-def resolve_routes():
-    json = get_frr_evpn_info()
-    vrfs = get_vrfs()
-
-    # The local router-id to search for IPs in the evpn routes information
-    localRouterId = json["bgpLocalRouterId"]
-    localAS = json["localAS"]
-
-    currentlyRouted = currently_routed([vrfs[vrf] for vrf in vrfs])
-
-    for jsonKey in json:
-        rd = jsonKey.split(":")
-        if len(rd) == 2:
-            peer, _ = rd
-
-            if parse_ip(peer) and peer == localRouterId:
-                rdObject = json[jsonKey]
-                for route in rdObject:
-                    matches = re.findall(r"(?:\[([^\]]*)\]:?)", route)
-                    if len(matches) == 6:
-                        route_type = matches[0]
-                        if route_type == "2":
-                            ip = parse_ip(matches[5])
-
-                            if ip != None and not ip.is_link_local:
-                                extendedCommunities = rdObject[route]["paths"][0][
-                                    "extendedCommunity"
-                                ]["string"]
-                                rts = re.finditer(
-                                    f"RT:{localAS}:(\d+)", extendedCommunities
-                                )
-
-                                # For all the matches we have in the extentendCommunity value
-                                for rt in rts:
-                                    vni = rt.group(1)
-                                    if vni in vrfs:
-                                        vrf = vrfs[vni]
-                                        if ip in currentlyRouted:
-                                            currentlyRouted.remove(ip)
-                                            break
-                                        
-                                        print(
-                                            f"wanting to add route {ip} to {vrf} ({vni}) vrf"
-                                        )
-                                        add_route_vrf(ip, vrf)
-                                        
-
-                                        break
-    for remove in currentlyRouted:
-        print(f"removing route for {remove}")
+def main():
+    print("frr-evpn-route-watcher by Matthieu P. <m@mpgn.dev>")
+    # Get all the L2 VRFs
+    vrfs = [
+        vrf 
+        for vrf in get_frr_vrfs()
+        if vrf['type'] == "L2"
+    ]
+    # get all the current routes
+    to_remove = get_current_routes()
+
+    for vrf in vrfs:
+        vrfName = vrf['tenantVrf']
+        vni = vrf['vni']
+        arp_cache = get_frr_arp_cache(vni)
+
+        for entry in arp_cache.keys():
+            local = type({}) == type(arp_cache[entry]) and \
+                arp_cache[entry]['type'] == 'local'
+            
+            if local:
+                ip = ipaddress.ip_address(entry)
+                present = ip in to_remove
+
+                # if the route already exists
+                if present:
+                    # if the route points to the correct VRF interface
+                    valid = to_remove[ip] == vrfName
+
+                    # if it's not, we delete the old route and
+                    # create a new correct one.
+                    if not valid:
+                        remove_route_vrf(ip)
+                        add_route_vrf(ip, vrfName)
+                else:
+                    # if the route doesn't exist, we simply create it
+                    add_route_vrf(ip, vrfName)
+                
+                # since the route muse say we remove it from the to_remove list
+                to_remove.pop(ip)
+    
+    for remove in to_remove.keys():
         remove_route_vrf(remove)
 
-resolve_routes()
+if __name__ == "__main__":
+    main()
diff --git a/frr-evpn-route-watcher_0.0.2_all.deb b/frr-evpn-route-watcher_0.0.2_all.deb
deleted file mode 100644
index f316b29..0000000
--- a/frr-evpn-route-watcher_0.0.2_all.deb
+++ /dev/null