movw $0x1f01,0xb8000; hlt;

I came across an interesting error when starting an ActiveMQ client the other day:

Could not connect to broker URL: tcp://activemq_qa.company.com:35000. Reason: java.lang.IllegalArgumentException: port out of range:-1

It turns out to be related to the DNS: java.net.URI.getHost() returns null if the DNS contains an underscore. The following JRuby snippet demonstrates it:

pierre % cat dns.rb
require "java"
include_class "java.net.URI"

INVALID_URI = "tcp://dns_foo.company.com:35000"
VALID_URI   = "tcp://dns-foo.company.com:35000"

u = URI.new(INVALID_URI)
puts u.getHost, u.getPort

v = URI.new(VALID_URI)
puts v.getHost, v.getPort

pierre % jruby dns.rb
nil
-1
dns-foo.company.com
35000

Hostnames are supposed to contain only letters, numbers and the hyphen. From rfc952:

1. A “name” (Net, Host, Gateway, or Domain name) is a text string up
to 24 characters drawn from the alphabet (A-Z), digits (0-9), minus
sign (-), and period (.).

I just wished the error was a bit more meaningful.

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