Automatically generate service types from the IANA registry

.gitignore

@@ -1,6 +1,7 @@
 .DS_Store
 .vscode
 /.build
+/Downloads
 /Packages
 /*.xcodeproj
 xcuserdata/

Scripts/generate-service-types

@@ -0,0 +1,92 @@
+#!/usr/bin/env python3
+
+from dataclasses import dataclass
+from datetime import datetime
+from pathlib import Path
+from typing import Iterable
+
+import argparse
+import csv
+import re
+import itertools
+import urllib.request
+
+ROOT_DIR = Path(__file__).resolve().parent.parent
+DOWNLOADS_DIR = ROOT_DIR / 'Downloads'
+DNSSERVICEDISCOVERY_SOURCES_DIR = ROOT_DIR / 'Sources' / 'DNSServiceDiscovery'
+
+CACHED_REGISTRY_PATH = DOWNLOADS_DIR / 'service-registry.csv'
+
+@dataclass
+class ServiceType:
+    name: str
+    port: str
+    protocol: str
+    description: str
+    assignee: str
+
+def camel_case(kebab_case: str) -> str:
+    segments = kebab_case.split('-')
+    return ''.join([segments[0]] + [s.capitalize() for s in segments[1:]])
+
+def fetch_service_types(registry_csv_url: str) -> Iterable[ServiceType]:
+    if not CACHED_REGISTRY_PATH.exists():
+        CACHED_REGISTRY_PATH.parent.mkdir(parents=True, exist_ok=True)
+        with urllib.request.urlopen(registry_csv_url) as u:
+            with open(CACHED_REGISTRY_PATH, 'wb') as f:
+                f.write(u.read())
+
+    with open(CACHED_REGISTRY_PATH, 'r') as f:
+        used = set()
+        reader = csv.reader(f)
+        for name, port, protocol, description, assignee, *_ in itertools.islice(reader, 1, None):
+            if re.fullmatch(r'[a-zA-Z][a-zA-Z0-9\-_]+', name) and protocol:
+                key = f'{name}-{protocol}'
+                if key not in used:
+                    used.add(key)
+                    yield ServiceType(
+                        name=name,
+                        port=port,
+                        protocol=protocol,
+                        description=description,
+                        assignee=assignee,
+                    )
+
+def swift_service_type_constant(service_type: ServiceType) -> str:
+    return f'public static let `{camel_case(f"{service_type.name}-{service_type.protocol}")}`: Self = "_{service_type.name}._{service_type.protocol}"'
+
+def swift_service_types_extension(registry_csv_url: str, service_types: Iterable[ServiceType]) -> str:
+    date = datetime.now().strftime('%Y-%m-%d')
+    return '\n'.join([
+        f'/// Auto-generated from {registry_csv_url}',
+        f'/// on {date}. Please do not edit this file, edit `Scripts/generate-service-types` instead!',
+        'extension DNSServiceType {',
+        *(line for s in service_types for line in [
+            f"    /// {' '.join(s.description.splitlines())} {s.assignee}",
+            f'    {swift_service_type_constant(s)}',
+        ]),
+        '}',
+    ])
+
+def main():
+    parser = argparse.ArgumentParser(description='Generates Swift definitions of known DNS service types from the IANA registry.')
+    parser.add_argument('-r', '--registry-csv-url', default='https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.csv')
+    parser.add_argument('-o', '--output', type=Path, default=DNSSERVICEDISCOVERY_SOURCES_DIR / 'DNSServiceType+Generated.swift')
+
+    args = parser.parse_args()
+
+    print('==> Fetching service types...')
+    service_types = fetch_service_types(args.registry_csv_url)
+
+    print('==> Generating Swift extension...')
+    extension = swift_service_types_extension(
+        registry_csv_url=args.registry_csv_url,
+        service_types=service_types
+    )
+
+    print(f'==> Writing {args.output}')
+    with open(args.output, 'w') as f:
+        f.write(extension)
+
+if __name__ == '__main__':
+    main()

Snippets/BrowseSSHServers.swift

@@ -4,7 +4,7 @@ import Dispatch
 let sd = DNSServiceDiscovery()
 
 print("Browsing for SSH servers...")
-sd.lookup(DNSServiceQuery(type: .ssh)) { instances in
+sd.lookup(DNSServiceQuery(type: .sshTcp)) { instances in
     for instance in try! instances.get() {
         print(instance)
     }

Snippets/ResolveAirPlayServers.swift

@@ -4,7 +4,7 @@ import Dispatch
 let sd = DNSServiceDiscovery()
 
 print("Resolving all AirPlay servers...")
-sd.lookup(DNSServiceQuery(type: .airplay)) {
+sd.lookup(DNSServiceQuery(type: .airplayTcp)) {
     let instances = try! $0.get()
     for instance in instances {
         sd.lookup(DNSServiceQuery(instance)) {

Snippets/SubscribeToAirPlayServers.swift

@@ -4,7 +4,7 @@ import Dispatch
 let sd = DNSServiceDiscovery()
 
 print("Subscribing to AirPlay servers...")
-let token = sd.subscribe(to: DNSServiceQuery(type: .airplay)) { instances in
+let token = sd.subscribe(to: DNSServiceQuery(type: .airplayTcp)) { instances in
     print(String(repeating: "-", count: 80))
     for instance in try! instances.get() {
         print(instance)