Print per-second summary statistics detailing a scan, similar to ZMap

[phillip-stephens]

Closes #472

Adds a per-second summary with the following:

• h/min/sec printout
• # of domains scanned
• domains/second
• success rate of domain resolution
• Occurrence of the different status codes, sorted greatest to least

A final summary is printed on scan completion

This is printed to stderr by default.

Two new CLI flags are available to modify this behavior:

  -q, --quiet                  do not print status updates
  -u, --status-updates-file=   file to write scan progress to, defaults to stderr (default: -)

Demo

$ cat status
00h:00m:01s; 67 domains scanned; 66.99 domains/sec.; 100.0% success rate; NOERROR: 67
00h:00m:02s; 91 domains scanned; 45.49 domains/sec.; 100.0% success rate; NOERROR: 91
00h:00m:03s; 96 domains scanned; 32.00 domains/sec.; 100.0% success rate; NOERROR: 96
00h:00m:04s; 97 domains scanned; 24.24 domains/sec.; 100.0% success rate; NOERROR: 97
00h:00m:05s; 98 domains scanned; 19.60 domains/sec.; 100.0% success rate; NOERROR: 98
00h:00m:06s; 98 domains scanned; 16.33 domains/sec.; 100.0% success rate; NOERROR: 98
00h:00m:07s; 98 domains scanned; 14.00 domains/sec.; 100.0% success rate; NOERROR: 98
00h:00m:08s; 98 domains scanned; 12.25 domains/sec.; 100.0% success rate; NOERROR: 98
00h:00m:09s; 99 domains scanned; 11.00 domains/sec.; 99.0% success rate; NOERROR: 98, ITERATIVE_TIMEOUT: 1
00h:00m:10s; 99 domains scanned; 9.90 domains/sec.; 99.0% success rate; NOERROR: 98, ITERATIVE_TIMEOUT: 1
00h:00m:11s; 99 domains scanned; 9.00 domains/sec.; 99.0% success rate; NOERROR: 98, ITERATIVE_TIMEOUT: 1
00h:00m:12s; 99 domains scanned; 8.25 domains/sec.; 99.0% success rate; NOERROR: 98, ITERATIVE_TIMEOUT: 1
00h:00m:13s; 100 domains scanned; 7.69 domains/sec.; 99.0% success rate; NOERROR: 99, ITERATIVE_TIMEOUT: 1
00h:00m:13s; Scan Complete, no more input. 100 domains scanned; 7.18 domains/sec.; 99.0% success rate; NOERROR: 99, ITERATIVE_TIMEOUT: 1

[zakird]

I don't think it's OK to make this not disable'able or not redirectable. I also don't think that it's OK to put these on stdout since it precludes piping ZDNS into another program. These should be able to be turned on and off and should be printed to stderr or a file.

The most useful thing in ZMap to make sure a scan looks good is hitrate, which you can't actually quite get here. Can we get the same thing here. When calculating hitrate I would include both NOERROR and NXDOMAIN because both are a successful response from the DNS server.

[phillip-stephens]

Yep all seems reasonable! Will make those changes