feat(bird): Add as_path.{contains,len}, net.len

pyproject.toml

@@ -0,0 +1,2 @@
+[tool.black]
+line-length = 79

roles/bird/filter_plugins/bird.py

@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 import itertools
+import re
 from dataclasses import dataclass
 from ipaddress import IPv4Address
 from typing import Any, Generic, Iterator, Literal, TypeVar
@@ -29,6 +30,30 @@ class AutoList(list[T], Generic[T]):
             return [parse_obj_as(T, value)]
 
 
+VARIABLES = {
+    "net.len": "net.len",
+}
+
+
+def interpolate(string: str, ctx: Context) -> str:
+    pattern = r"(?<!\\)(\$\{[_a-z][_a-z0-9.]*\})"
+
+    def lookup(var: str) -> str:
+        try:
+            return VARIABLES[var]
+        except KeyError:
+            return quoted(getattr(ctx, var))
+
+    split = re.split(pattern, string)
+    parts = [
+        (lookup(p[2:-1]) if re.match(pattern, p) else quoted(p))
+        for p in split
+        if p
+    ]
+
+    return ", ".join(parts)
+
+
 class Proto(BaseModel):
     protos: AutoList[str]
 
@@ -49,7 +74,28 @@ class Not(BaseModel):
     condition: Condition = Field(alias="not")
 
 
-Condition = Proto | Source | And | Or | Not
+class AsPathContains(BaseModel):
+    contains: AutoList[int] = Field(alias="as_path.contains")
+
+
+class AsPathLength(BaseModel):
+    length: list[int] = Field(
+        ge=0, min_items=2, max_items=2, alias="as_path.len"
+    )
+
+
+class IPv4orIPv6(BaseModel):
+    ipv4: list[int] = Field(ge=0, min_items=2, max_items=2)
+    ipv6: list[int] = Field(ge=0, min_items=2, max_items=2)
+
+
+class NetLength(BaseModel):
+    length: IPv4orIPv6 = Field(alias="net.len")
+
+
+Condition = (
+    Proto | Source | And | Or | Not | AsPathContains | AsPathLength | NetLength
+)
 
 And.update_forward_refs()
 Or.update_forward_refs()
@@ -61,6 +107,10 @@ Accept = Literal["accept"]
 Reject = Literal["reject"]
 
 
+class RejectWithMsg(BaseModel):
+    reject: str
+
+
 class PrefSrc(BaseModel):
     pref_src: AutoList[IPvAnyAddress]
 
@@ -70,7 +120,7 @@ class Conditional(BaseModel):
     actions: AutoList[Action] = Field(alias="then")
 
 
-Action = Accept | Reject | PrefSrc | Conditional
+Action = Accept | Reject | RejectWithMsg | PrefSrc | Conditional
 
 Conditional.update_forward_refs()
 
@@ -144,12 +194,31 @@ def str_of_condition(condition: Condition, ctx: bool) -> str:
             sources = [str(s) for s in sources]
             return f"krt_source ~ [ {', '.join(sources)} ]"
 
+        case AsPathContains(contains=contains):
+            return (
+                f"bgp_path ~ [ {', '.join([str(asn) for asn in contains])} ]"
+            )
+
+        case AsPathLength(length=[min_len, max_len]):
+            return f"{min_len} <= bgp_path.len && bgp_path.len <= {max_len}"
+
+        case NetLength(
+            length=IPv4orIPv6(ipv4=[min_v4, max_v4], ipv6=[min_v6, max_v6])
+        ):
+            if ctx.ipv4:
+                return f"{min_v4} <= net.len && net.len <= {max_v4}"
+            else:
+                return f"{min_v6} <= net.len && net.len <= {max_v6}"
+
 
 def lines_of_action(action: Action, ctx: Context) -> Iterable[str]:
     match action:
         case "accept" | "reject":
             yield f"{action};"
 
+        case RejectWithMsg(reject=reason):
+            yield f"reject {interpolate(reason, ctx)};"
+
         case Conditional(condition=condition, actions=actions):
             yield f"if {str_of_condition(condition, ctx)} then {'{'}"
             yield from indent(

roles/bird/templates/bird.conf.j2

@@ -27,8 +27,8 @@ protocol device {
 
 {% for name, kernel in bird__kernel.items() %}
 {% for version in ["ipv4", "ipv6"] %}
-{% set ipv4 = version == "ipv4" %}
-protocol kernel {{ name | bird_name(ipv4) }} {
+{% set is_ipv4 = version == "ipv4" %}
+protocol kernel {{ name | bird_name(is_ipv4) }} {
 {% if kernel.kernel is defined %}
     kernel table {{ kernel.kernel }};
 {% endif %}
@@ -40,9 +40,9 @@ protocol kernel {{ name | bird_name(ipv4) }} {
 {% endif %}
     {{ version }} {
 {% if kernel.table is defined %}
-        table {{ kernel.table | bird_name(ipv4) }};
+        table {{ kernel.table | bird_name(is_ipv4) }};
 {% endif %}
-        {{ import_export(kernel, ipv4) | indent(8) }}
+        {{ import_export(kernel, is_ipv4) | indent(8) }}
     };
 }
 {% endfor %}
@@ -50,25 +50,25 @@ protocol kernel {{ name | bird_name(ipv4) }} {
 
 {% for name, pipe in bird__pipes.items() %}
 {% for version in ["ipv4", "ipv6"] %}
-{% set ipv4 = version == "ipv4" %}
-protocol pipe {{ name | bird_name(ipv4) }} {
-    table {{ pipe.table | bird_name(ipv4) }};
-    peer table {{ pipe.peer_table | default("master") | bird_name(ipv4) }};
-    {{ import_export(kernel, ipv4) | indent(4) }}
+{% set is_ipv4 = version == "ipv4" %}
+protocol pipe {{ name | bird_name(is_ipv4) }} {
+    table {{ pipe.table | bird_name(is_ipv4) }};
+    peer table {{ pipe.peer_table | default("master") | bird_name(is_ipv4) }};
+    {{ import_export(kernel, is_ipv4) | indent(4) }}
 }
 {% endfor %}
 {% endfor %}
 
 {% if bird__ospf is defined %}
 {% for version in ["ipv4", "ipv6"] %}
-{% set ipv4 = version == "ipv4" %}
-{% set ospf_version = "v2" if ipv4 else "v3" %}
-protocol ospf {{ ospf_version }} {{ "ospf" | bird_name(ipv4) }} {
+{% set is_ipv4 = version == "ipv4" %}
+{% set ospf_version = "v2" if is_ipv4 else "v3" %}
+protocol ospf {{ ospf_version }} {{ "ospf" | bird_name(is_ipv4) }} {
     {{ version }} {
 {% if bird__ospf.table is defined %}
-        table {{ bird__ospf.table | bird_name(ipv4) }};
+        table {{ bird__ospf.table | bird_name(is_ipv4) }};
 {% endif %}
-        {{ import_export(bird__ospf, ipv4) | indent(8) }}
+        {{ import_export(bird__ospf, is_ipv4) | indent(8) }}
     };
 {% for id, area in bird__ospf.areas.items() %}
     area {{ id }} {
@@ -92,8 +92,8 @@ protocol ospf {{ ospf_version }} {{ "ospf" | bird_name(ipv4) }} {
 
 {% for name, bgp in bird__bgp.items() %}
 {% for version in ["ipv4", "ipv6"] %}
-{% set ipv4 = version == "ipv4" %}
-protocol bgp {{ name | bird_name(ipv4) }} {
+{% set is_ipv4 = version == "ipv4" %}
+protocol bgp {{ name | bird_name(is_ipv4) }} {
     local {{ bgp.local.address
              | ansible.utils.ipaddr(version)
              | first }} as {{ bgp.local.as }};
@@ -106,12 +106,12 @@ protocol bgp {{ name | bird_name(ipv4) }} {
 {% endif %}
     {{ version }} {
 {% if bgp.table is defined %}
-        table {{ bgp.table | bird_name(ipv4) }};
+        table {{ bgp.table | bird_name(is_ipv4) }};
 {% endif %}
 {% if bgp.next_hop_self is defined %}
         next hop self;
 {% endif %}
-        {{ import_export(bgp, ipv4) | indent(8) }}
+        {{ import_export(bgp, is_ipv4) | indent(8) }}
     };
 }
 {% endfor %}