Implement --list and --list-all commands

Requires a MSRV of 1.44 due to the transitive dependency on bitvec 0.19.

src/main.rs

@@ -1,11 +1,44 @@
 use age_plugin::run_state_machine;
 use gumdrop::Options;
+use yubikey_piv::{
+    certificate::PublicKeyInfo,
+    key::{RetiredSlotId, SlotId},
+    Key, Readers,
+};
 
 mod error;
+mod p256;
 mod plugin;
+mod util;
 
 use error::Error;
 
+const PLUGIN_NAME: &str = "age-plugin-yubikey";
+const RECIPIENT_PREFIX: &str = "age1yubikey";
+
+const USABLE_SLOTS: [RetiredSlotId; 20] = [
+    RetiredSlotId::R1,
+    RetiredSlotId::R2,
+    RetiredSlotId::R3,
+    RetiredSlotId::R4,
+    RetiredSlotId::R5,
+    RetiredSlotId::R6,
+    RetiredSlotId::R7,
+    RetiredSlotId::R8,
+    RetiredSlotId::R9,
+    RetiredSlotId::R10,
+    RetiredSlotId::R11,
+    RetiredSlotId::R12,
+    RetiredSlotId::R13,
+    RetiredSlotId::R14,
+    RetiredSlotId::R15,
+    RetiredSlotId::R16,
+    RetiredSlotId::R17,
+    RetiredSlotId::R18,
+    RetiredSlotId::R19,
+    RetiredSlotId::R20,
+];
+
 #[derive(Debug, Options)]
 struct PluginOptions {
     #[options(help = "Print this help message and exit.")]
@@ -31,6 +64,61 @@ struct PluginOptions {
     list_all: bool,
 }
 
+fn list(all: bool) -> Result<(), Error> {
+    let mut readers = Readers::open()?;
+
+    for reader in readers.iter()? {
+        let mut yubikey = reader.open()?;
+
+        for key in Key::list(&mut yubikey)? {
+            // We only use the retired slots.
+            let slot = match key.slot() {
+                SlotId::Retired(slot) => slot,
+                _ => continue,
+            };
+
+            // Only P-256 keys are compatible with us.
+            let recipient = match key.certificate().subject_pki() {
+                PublicKeyInfo::EcP256(pubkey) => match p256::Recipient::from_pubkey(*pubkey) {
+                    Some(recipient) => recipient,
+                    None => continue,
+                },
+                _ => continue,
+            };
+
+            let ((name, pin_policy, touch_policy), created) =
+                match x509_parser::parse_x509_certificate(key.certificate().as_ref())
+                    .ok()
+                    .and_then(|(_, cert)| {
+                        util::extract_name_and_policies(&mut yubikey, &key, &cert, all)
+                            .map(|res| (res, cert.validity().not_before.to_rfc2822()))
+                    }) {
+                    Some(res) => res,
+                    None => continue,
+                };
+
+            println!(
+                "#       Serial: {}, Slot: {}",
+                yubikey.serial(),
+                // Use 1-indexing in the UI for niceness
+                USABLE_SLOTS.iter().position(|s| s == &slot).unwrap() + 1,
+            );
+            println!("#         Name: {}", name);
+            println!("#      Created: {}", created);
+            println!("#   PIN policy: {}", util::pin_policy_to_str(pin_policy));
+            println!(
+                "# Touch policy: {}",
+                util::touch_policy_to_str(touch_policy)
+            );
+            println!("{}", recipient.to_string());
+            println!();
+        }
+        println!();
+    }
+
+    Ok(())
+}
+
 fn main() -> Result<(), Error> {
     let opts = PluginOptions::parse_args_default_or_exit();
 
@@ -55,9 +143,9 @@ fn main() -> Result<(), Error> {
     } else if opts.identity {
         todo!()
     } else if opts.list {
-        todo!()
+        list(false)
     } else if opts.list_all {
-        todo!()
+        list(true)
     } else {
         // TODO: CLI identity generation
         Ok(())