const-oid: provide shortest_by_oid lookups

const-oid/src/db.rs

@@ -36,6 +36,7 @@ const fn eq_case(lhs: &[u8], rhs: &[u8]) -> bool {
 }
 
 /// A query interface for OIDs/Names.
+#[derive(Copy, Clone)]
 pub struct Database<'a>(&'a [(&'a ObjectIdentifier, &'a str)]);
 
 impl<'a> Database<'a> {
@@ -82,6 +83,43 @@ impl<'a> Database<'a> {
 
         None
     }
+
+    /// Finds the shortest named oid by its associated OID.
+    pub const fn find_names_for_oid<'o>(&self, oid: &'o ObjectIdentifier) -> Names<'a, 'o> {
+        Names {
+            database: *self,
+            oid,
+            position: 0,
+        }
+    }
+}
+
+/// Iterator returning the multiple names that may be associated with an OID.
+pub struct Names<'a, 'o> {
+    database: Database<'a>,
+    oid: &'o ObjectIdentifier,
+    position: usize,
+}
+
+impl<'a, 'o> Iterator for Names<'a, 'o> {
+    type Item = &'a str;
+
+    fn next(&mut self) -> Option<&'a str> {
+        let mut i = self.position;
+
+        while i < self.database.0.len() {
+            let lhs = self.database.0[i].0;
+
+            if lhs.buffer.eq(&self.oid.buffer) {
+                self.position = i + 1;
+                return Some(self.database.0[i].1);
+            }
+
+            i += 1;
+        }
+
+        return None;
+    }
 }
 
 #[cfg(test)]

x509-cert/Cargo.toml

@@ -15,7 +15,7 @@ edition = "2021"
 rust-version = "1.65"
 
 [dependencies]
-const-oid = { version = "0.9.2", features = ["db"] } # TODO: path = "../const-oid"
+const-oid = { version = "0.10.0-pre", features = ["db"] } # TODO: path = "../const-oid"
 der = { version = "0.7.6", features = ["alloc", "derive", "flagset", "oid"] }
 spki = { version = "0.7.2", features = ["alloc"] }
 

x509-cert/src/attr.rs

@@ -3,7 +3,7 @@
 use alloc::vec::Vec;
 use const_oid::db::{
     rfc4519::{COUNTRY_NAME, DOMAIN_COMPONENT, SERIAL_NUMBER},
-    DB,
+    Database, DB,
 };
 use core::{
     fmt::{self, Write},
@@ -260,7 +260,7 @@ impl fmt::Display for AttributeTypeAndValue {
             _ => None,
         };
 
-        if let (Some(key), Some(val)) = (DB.by_oid(&self.oid), val) {
+        if let (Some(key), Some(val)) = (DB.shortest_name_by_oid(&self.oid), val) {
             write!(f, "{}=", key.to_ascii_uppercase())?;
 
             let mut iter = val.char_indices().peekable();
@@ -285,3 +285,26 @@ impl fmt::Display for AttributeTypeAndValue {
         Ok(())
     }
 }
+
+/// Helper trait to bring shortest name by oid lookups to Database
+trait ShortestName {
+    fn shortest_name_by_oid(&self, oid: &ObjectIdentifier) -> Option<&str>;
+}
+
+impl<'a> ShortestName for Database<'a> {
+    fn shortest_name_by_oid(&self, oid: &ObjectIdentifier) -> Option<&'a str> {
+        let mut best_match: Option<&'a str> = None;
+
+        for m in self.find_names_for_oid(oid) {
+            if let Some(previous) = best_match {
+                if m.len() < previous.len() {
+                    best_match = Some(m);
+                }
+            } else {
+                best_match = Some(m);
+            }
+        }
+
+        best_match
+    }
+}

x509-cert/tests/name.rs

@@ -85,7 +85,7 @@ fn decode_name() {
         let rdn1 = Name::from_der(&hex!("3081c0310b30090603550406130255533113301106035504080c0a43616c69666f726e69613116301406035504070c0d4d6f756e7461696e205669657731133011060355040a0c0a476f6f676c65204c4c43311e301c06035504030c154f51464176444e4457732e676f6f676c652e636f6d31243022060355040b0c1b6d616e6167656d656e743a64732e67726f75702e3338393131313131293027060a0992268993f22c6401010c196964656e746974793a64732e67726f75702e33383931313131")[..]);
         let rdn1a = rdn1.unwrap();
         let name = rdn1a.to_string();
-        assert_eq!(name, "UID=identity:ds.group.3891111,OU=management:ds.group.3891111,CN=OQFAvDNDWs.google.com,O=Google LLC,L=Mountain View,STATEORPROVINCENAME=California,C=US");
+        assert_eq!(name, "UID=identity:ds.group.3891111,OU=management:ds.group.3891111,CN=OQFAvDNDWs.google.com,O=Google LLC,L=Mountain View,ST=California,C=US");
     }
 }