Merge pull request #99 from thekuwayama/ech_outer_extensions__8

[ech_outer_extensions] 8. improvement: example; add resolve_echconfig

Author: thekuwayama

example/helper.rb

@@ -94,3 +94,14 @@ def parse_echconfigs_pem(pem)
 
   ECHConfig.decode_vectors(b.slice(2..))
 end
+
+def resolve_echconfig(hostname)
+  rr = Resolv::DNS.new.getresources(
+    hostname,
+    Resolv::DNS::Resource::IN::HTTPS
+  )
+  raise "failed to resolve echconfig via #{hostname} HTTPS RR" \
+    if rr.first.nil? || !rr.first.svc_params.keys.include?('ech')
+
+  rr.first.svc_params['ech'].echconfiglist.first
+end

example/https_client_using_ech.rb

@@ -9,11 +9,7 @@
 ech_config = if ARGV.length > 1
                parse_echconfigs_pem(File.open(ARGV[1]).read).first
              else
-               rr = Resolv::DNS.new.getresources(
-                 uri.host,
-                 Resolv::DNS::Resource::IN::HTTPS
-               )
-               rr.first.svc_params['ech'].echconfiglist.first
+               resolve_echconfig(uri.host)
              end
 
 socket = TCPSocket.new(uri.host, uri.port)

example/https_client_using_hrr_and_ech.rb

@@ -9,11 +9,7 @@
 ech_config = if ARGV.length > 1
                parse_echconfigs_pem(File.open(ARGV[1]).read).first
              else
-               rr = Resolv::DNS.new.getresources(
-                 uri.host,
-                 Resolv::DNS::Resource::IN::HTTPS
-               )
-               rr.first.svc_params['ech'].echconfiglist.first
+               resolve_echconfig(uri.host)
              end
 
 socket = TCPSocket.new(uri.host, uri.port)

example/https_client_using_ticket_and_ech.rb

@@ -9,11 +9,7 @@
 ech_config = if ARGV.length > 1
                parse_echconfigs_pem(File.open(ARGV[1]).read).first
              else
-               rr = Resolv::DNS.new.getresources(
-                 uri.host,
-                 Resolv::DNS::Resource::IN::HTTPS
-               )
-               rr.first.svc_params['ech'].echconfiglist.first
+               resolve_echconfig(uri.host)
              end
 
 settings_2nd = {