initial git push

.gitignore

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+gen
+aspa-*.json

.vscode/settings.json

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+{
+    "deno.enable": true
+}

gen.ts

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+import { parseArgs } from "https://deno.land/std@0.207.0/cli/parse_args.ts";
+
+type ASN = `AS${string}`;
+
+interface ASA {
+    customer: ASN;
+    providers: ASN[];
+    ta: string;
+}
+
+const printf = console.log;
+
+const flags = parseArgs(Deno.args, {
+    string: ["input", "output"],
+    boolean: ["strict", "verbose", "help"],
+    alias: {
+        i: "input",
+        o: "output",
+        s: "strict",
+        v: "verbose",
+        h: "help"
+    }
+});
+
+if (flags.help) {
+    printf(`Usage: ${Deno.execPath()} [OPTIONS]
+Options:
+    --help,    -h   Show this menu.
+    --verbose, -v   Show warnings.
+    --input,   -i   The input file generated by \`routinator\`. (required) 
+    --output,  -i   The file to output the BIRD2 function to.
+    --strict,  -s   Consider paths without ASPA invalid (NOT RECOMMENDED).`);
+
+    Deno.exit(0);
+}
+
+let failed = false;
+if (!flags.input) {
+    failed = true;
+    printf("(error) `--input` flag not specified.");
+}
+
+if (!flags.output && flags.verbose) {
+    printf("(warn) `--output` flag not specified.");
+}
+
+if (failed) {
+    Deno.exit(1);
+}
+
+const data = await Deno.readTextFile(flags.input as string); // we know flags.input will not be undefined by this point.
+
+const json = parseData(data);
+if (!json) {
+    printf(`(error) could not parse json from \`${flags.input}\``);
+    Deno.exit(2);
+}
+
+const aspas: ASA[] = json.aspas;
+if (!aspas) {
+    printf(`(error) property \`aspas\` does not exist on the parsed JSON from \`${flags.input}\``);
+    Deno.exit(3);
+}
+
+let txt = "function is_aspa_valid () {\n";
+
+const LEADING_AS = /^AS/g;
+for (const {customer, providers} of aspas) {
+    const asn = customer.replace(LEADING_AS, '');
+
+    txt += `   # does the AS path include ${customer}?\n`
+    txt += `   if (bgp_path ~ [= * ${asn} * =]) then {\n`;
+    txt += `       # does the AS path include [carrier's asn, ${customer}]?\n`
+    for (const provider of providers) {
+        const carrier = provider.replace(LEADING_AS, '');
+
+        txt += `       if (bgp_path ~ [= * ${carrier} ${asn} * =]) then return true;\n`;
+    }
+    txt += '       return false;\n';
+    txt += '   }\n\n'
+}
+
+if (flags.strict) {
+    txt += '   # (strict mode) if no previous condition matches there exists no ASPA for the path; it is invalid.\n';
+    txt += '   return false;\n';
+} else {
+    txt += '   # to avoid breaking stuff, assume the path is valid if no ASA exists.\n';
+    txt += '   return true;\n';
+}
+txt += '}\n';
+
+if (!flags.output) {
+    console.log(txt);
+
+    Deno.exit(0);
+}
+
+try {
+    await Deno.writeTextFile(flags.output, txt);
+} catch (e) {
+    printf(`(error) writing to disk raised: ${e}`);
+}
+
+function parseData(data: string) {
+    try {
+        return JSON.parse(data);
+    } catch {
+        return null;
+    }
+}

readme.md

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+## "Compilation" to a stand-alone binary
+
+This is as easy as running the following command:
+
+```
+deno compile --allow-read --allow-write ./gen.ts
+```
+
+# my sticky notes:
+
+## 1:
+
+the as_path filters used:
+
+is the asn in the path?
+`bgp_path ~ [= * <ASN> * =]`
+
+is the carrier + the asn in the path?
+`bgp_path ~ [= * <CARRIER> <ASN> * =]`
+
+## 2:
+
+get just the aspa dump from routinator:
+
+```
+routinator --enable-aspa vrps -f json -o /root/dump.json --no-route-origins --no-router-keys
+```
+
+this is probably missing a flag to skip tls verification for idiots (the ASAs are signed anyway?):
+
+`[WARN] RRDP https://rpki.cnnic.cn/rrdp/notify.xml: error sending request for url (https://rpki.cnnic.cn/rrdp/notify.xml): error trying to connect: invalid peer certificate: UnknownIssuer`