Add a tool for listening to RBN data

scripts/rbn-grep

@@ -0,0 +1,88 @@
+#! /usr/bin/env python3
+import argparse
+import sys
+import re
+import socket
+
+
+def main() -> int:
+    # Handle program arguments
+    ap = argparse.ArgumentParser(
+        prog="rbn-grep", description="Grep against RBN data in real-time"
+    )
+    ap.add_argument(
+        "--callsign", "-c", help="REGEX for the TX-ing callsign", default=".*"
+    )
+    ap.add_argument(
+        "--spotter", "-s", help="REGEX for the spotting callsign", default=".*"
+    )
+    ap.add_argument(
+        "--min-frequency", "--fl", help="Minimum frequency in kc", type=float, default=0
+    )
+    ap.add_argument(
+        "--max-frequency",
+        "--fh",
+        help="Maximum frequency in kc",
+        type=float,
+        default=sys.maxsize,
+    )
+    ap.add_argument(
+        "--stream-type",
+        "--st",
+        help="Stream type",
+        default="analog",
+        choices=["analog", "digital"],
+    )
+    ap.add_argument("--login-callsign", help="Login callsign", default="n0call")
+    args = ap.parse_args()
+
+    # Compile regexes
+    callsign_regex = re.compile(args.callsign, re.IGNORECASE)
+    spotter_regex = re.compile(args.spotter, re.IGNORECASE)
+
+    # Connect to the RBN Telnet servers
+    conn = socket.create_connection(
+        ("telnet.reversebeacon.net", 7000 if args.stream_type == "analog" else 7001)
+    )
+
+    # Log in
+    conn.send(f"{args.login_callsign}\n".encode("ascii"))
+
+    # Read lines and filter
+    try:
+        while True:
+            # Read a line
+            lines = conn.recv(1024).decode("ascii").strip()
+            for line in lines.splitlines():
+                line_split = [x for x in line.split(" ") if x]
+
+                # Ignore bad lines
+                if not line.startswith("DX"):
+                    continue
+
+                # Parse the data
+                spotter = line_split[2]
+                frequency_kc = float(line_split[3])
+                spotted = line_split[4]
+
+                # Filter
+                if (
+                    not callsign_regex.match(spotted)
+                    or not spotter_regex.match(spotter)
+                    or frequency_kc < args.min_frequency
+                    or frequency_kc > args.max_frequency
+                ):
+                    continue
+
+                # Print the line
+                print(line)
+
+    except KeyboardInterrupt:
+        print("\nGoodbye")
+        conn.close()
+
+    return 0
+
+
+if __name__ == "__main__":
+    sys.exit(main())