added aws_lambda code

aws_lambda/domaincheck/lambda_function.py

@@ -0,0 +1,62 @@
+"""
+This module contains a Lambda function that checks if domains are reachable and retrieves SSL information.
+Amazon will bill for the wait time of this function, timeout is set to 10 seconds.
+TODO: Implement a loop with asynchronous checking of multiple domains.
+"""
+
+import requests
+import ssl
+import socket
+from datetime import datetime
+
+def lambda_handler(event, context):
+    """
+    Args:
+        event (dict):
+            The event data passed to the Lambda function. Expects a dictionary
+            with a "hostnames" key containing a list of all hosts to be checked.
+        context (LambdaContext):
+            The runtime information of the Lambda function.
+    """
+    max_timeout = 10
+    remaining_time_in_seconds = context.get_remaining_time_in_millis() / 1000
+    timeout_in_seconds = min(remaining_time_in_seconds - 1, max_timeout)
+    results = {}
+    for hostname in event["hostnames"]:
+        url = f"https://{hostname}/"
+        host_result = {}
+        host_result["https_get_request"] = get_request(url, timeout=timeout_in_seconds)
+        if host_result["https_get_request"].get("reachable"):
+            host_result["ssl"] = ssl_info(hostname)
+        results[hostname] = host_result
+    return results
+
+
+def get_request(url, timeout=10):
+    result = {}
+    try:
+        resp = requests.get(url, timeout=timeout)
+        result["status_code"] = resp.status_code
+        result["reason"] = resp.reason
+        result["reachable"] = resp.status_code == 200
+    except requests.exceptions.RequestException as e:
+        result["error"] = str(e)
+        result["reachable"] = False
+    return result
+
+
+def ssl_info(hostname, port=443):
+    try:
+        ctx = ssl.create_default_context()
+        with socket.create_connection((hostname, port), timeout=10) as sock:
+            with ctx.wrap_socket(sock, server_hostname=hostname) as ssock:
+                cert = ssock.getpeercert()
+                issuer = dict(x[0] for x in cert['issuer'])
+                not_after = datetime.strptime(cert['notAfter'], "%b %d %H:%M:%S %Y %Z")
+                return {
+                    "issuer": issuer.get("organizationName", "Unknown"),
+                    "expiry": not_after.strftime("%Y-%m-%d %H:%M:%S"),
+                    "valid": not_after > datetime.utcnow()
+                }
+    except Exception as e:
+        return {"error": str(e)}