Fix introducer list subcommand

- Add a list of introduced domains to the output.
- Fix `regex_domain_unescape()` to return an error if the regular
  expression differs from a regex for a domain.

src/common/escape.rs

@@ -3,6 +3,8 @@
 use aho_corasick::AhoCorasick;
 use anyhow::Result;
 
+use crate::types::errors::HuskError;
+
 const REGEX_CONTROL_CHARS: &[&str]
     = &[ "\\", ".", "|", "(", ")", "*", "+", "?", "^", "$", "[", "]" ];
 const REGEX_ESCAPED_CHARS: &[&str]
@@ -36,10 +38,10 @@ pub fn regex_domain_unescape(value: &str) -> Result<String> {
         if let Some(inner) = stripped.strip_suffix(">$") {
             Ok(inner.into())
         } else {
-            Ok(value)
+            Err(HuskError::InvalidDomainName(value).into())
         }
     } else {
-        Ok(value)
+        Err(HuskError::InvalidDomainName(value).into())
     }
 }
 

src/types/introducer.rs

@@ -9,6 +9,7 @@ use sequoia_openpgp::Cert;
 
 use crate::types::husk_context::HuskContext;
 use crate::common::crypto;
+use crate::common::escape;
 
 #[derive(thiserror::Error, Debug)]
 pub enum IntroducerError {
@@ -105,16 +106,28 @@ impl Introducer {
 }
 
 use std::fmt::{Display, Formatter};
-impl Display for Introducer {
 
+impl Display for Introducer {
     fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
         // XXX: This is unsafe as ANSI control chars are not handled.
         let uids = self.cert.userids()
             .map(|u| String::from_utf8_lossy(u.userid().value()).to_string())
             .collect::<Vec<String>>()
             .join(", ");
+
         writeln!(f, "Introducer: {}", self.cert.fingerprint())?;
         writeln!(f, "  UserIDs: {}", uids)?;
+
+        if let Some(regex_set) = self.certification.regular_expressions() {
+            for regex in regex_set.as_bytes().into_iter() {
+                let regex = String::from_utf8_lossy(regex);
+                if let Ok(domain) = escape::regex_domain_unescape(regex.to_string().as_str()) {
+                    writeln!(f,"  Domain: {}", domain)?;
+                } else {
+                    writeln!(f,"  RegEx: {}", regex)?;
+                }
+            }
+        }
         Ok(())
     }
 }