samples/probe_dump.py: add --json option

samples/probe_dump.py

@@ -6,10 +6,60 @@
 """A simple Knot DNS probe client."""
 
 import argparse
+import datetime
+import json
 import libknot
 import libknot.probe
 import sys
 
+def extract_dns_header(probe, fieldname):
+    val = getattr(probe, fieldname)
+    return {
+        "additionals": val.additionals,
+        "answers":     val.answers,
+        "authorities": val.authorities,
+        "flag_aa":     val.flag_aa,
+        "flag_ad":     val.flag_ad,
+        "flag_cd":     val.flag_cd,
+        "flag_qr":     val.flag_qr,
+        "flag_ra":     val.flag_ra,
+        "flag_rd":     val.flag_rd,
+        "flag_tc":     val.flag_tc,
+        "flag_z":      val.flag_z,
+        "id":          val.id,
+        "opcode":      val.opcode,
+        "questions":   val.questions,
+        "rcode":       val.rcode,
+    }
+
+def extract_addr(probe, fieldname):
+    val = getattr(probe, fieldname)
+    return probe.addr_str(val)
+
+def extract_safe(probe, fieldname):
+    convert_func = getattr
+    try:
+        convert_func = {
+            'local_addr':  extract_addr,
+            'remote_addr': extract_addr,
+            'query_hdr':   extract_dns_header,
+            'reply_hdr':   extract_dns_header,
+            'query_name':  lambda probe, _: probe.qname_str(),
+        }[fieldname]
+    except KeyError:
+        pass
+
+    return convert_func(probe, fieldname)
+
+def convert_json(probe):
+    probe_as_dict = {}
+    for field in probe._fields_:
+        fieldname = field[0]
+        fieldtype = field[1]
+        fieldlen  = field[2] if len(field) > 2 else None
+
+        probe_as_dict[fieldname] = extract_safe(probe, fieldname)
+    return probe_as_dict
 
 def probe_loop(args):
     try:
@@ -25,7 +75,14 @@ def probe_loop(args):
         while (True):
             if probe.consume(data, 1000) > 0:
                 for item in data:
-                    print(item.str(color=not args.no_color, timestamp=not args.no_timestamp))
+                    if args.json:
+                        item_json = convert_json(item)
+                        if not args.no_timestamp:
+                            item_json["timestamp"] = datetime.datetime.now().isoformat()
+                        log = json.dumps(item_json)
+                    else:
+                        log = item.str(color=not args.no_color, timestamp=not args.no_timestamp)
+                    print(log)
     except KeyboardInterrupt:
         sys.exit(0)
 
@@ -49,10 +106,15 @@ if __name__ == "__main__":
         default=1,
         help="the probe channel"
     )
+    parser.add_argument(
+        "--json",
+        action='store_true',
+        help="Print JSON formatted"
+    )
     parser.add_argument(
         "--no-color",
         action='store_true',
-        help="don't colorize the output"
+        help="don't colorize the output (JSON is never colorized)"
     )
     parser.add_argument(
         "--no-timestamp",