openpgp: Change SubpacketValue::Unknown to store the tag.

  - Makes it possible to construct unknown packets with arbitrary
    subpacket tags.

  - Fixes a regression.

4 files changed, 19 insertions, 12 deletions

diff --git a/openpgp/examples/statistics.rs b/openpgp/examples/statistics.rs
index 0b453467..c990fb58 100644
--- a/openpgp/examples/statistics.rs
+++ b/openpgp/examples/statistics.rs
@@ -149,7 +149,7 @@ fn main() {
                         sigs_subpacket_tags_count[i] += 1;
                         cert.sigs_subpacket_tags_count[i] += 1;
                         signature.subpacket_tags_count[i] += 1;
-                        if let SubpacketValue::Unknown(_) = sub.value() {
+                        if let SubpacketValue::Unknown { .. } = sub.value() {
                             sigs_subpacket_tags_unknown
                                 [u8::from(sub.tag()) as usize] += 1;
                         } else {
@@ -165,7 +165,8 @@ fn main() {
                             }
 
                             match sub.value() {
-                                SubpacketValue::Unknown(_) => unreachable!(),
+                                SubpacketValue::Unknown { .. } =>
+                                    unreachable!(),
                                 SubpacketValue::KeyFlags(k) =>
                                     if let Some(count) = key_flags.get_mut(&k) {
                                         *count += 1;
diff --git a/openpgp/src/packet/signature/subpacket.rs b/openpgp/src/packet/signature/subpacket.rs
index e37da609..5544e66d 100644
--- a/openpgp/src/packet/signature/subpacket.rs
+++ b/openpgp/src/packet/signature/subpacket.rs
@@ -562,8 +562,13 @@ impl NotationDataFlags {
 /// description of these tags.
 #[derive(Debug, PartialEq, Eq, Hash, Clone)]
 pub enum SubpacketValue {
-    /// The subpacket is unknown.
-    Unknown(Vec<u8>),
+    /// An unknown subpacket.
+    Unknown {
+        /// The unknown subpacket's tag.
+        tag: SubpacketTag,
+        /// The unknown subpacket's uninterpreted body.
+        body: Vec<u8>
+    },
 
     /// 4-octet time field
     SignatureCreationTime(Timestamp),
@@ -704,7 +709,7 @@ impl SubpacketValue {
                 // Educated guess for unknown versions.
                 Fingerprint::Invalid(_) => 1 + fp.as_slice().len(),
             },
-            Unknown(u) => u.len(),
+            Unknown { body, .. } => body.len(),
         }
     }
 
@@ -744,8 +749,7 @@ impl SubpacketValue {
             PreferredAEADAlgorithms(_) =>
                 Ok(SubpacketTag::PreferredAEADAlgorithms),
             IntendedRecipient(_) => Ok(SubpacketTag::IntendedRecipient),
-            _ => Err(Error::InvalidArgument(
-                "Unknown or invalid subpacket value".into()).into()),
+            Unknown { tag, .. } => Ok(*tag),
         }
     }
 }
diff --git a/openpgp/src/parse/parse.rs b/openpgp/src/parse/parse.rs
index 1c6bc4ec..9c08867a 100644
--- a/openpgp/src/parse/parse.rs
+++ b/openpgp/src/parse/parse.rs
@@ -1412,8 +1412,10 @@ impl Subpacket {
                 | SubpacketTag::PlaceholderForBackwardCompatibility
                 | SubpacketTag::Private(_)
                 | SubpacketTag::Unknown(_) =>
-                SubpacketValue::Unknown(
-                    php.parse_bytes("unknown subpacket", len)?),
+                SubpacketValue::Unknown {
+                    tag,
+                    body: php.parse_bytes("unknown subpacket", len)?,
+                },
         };
 
         let total_out = php.reader.total_out();
diff --git a/openpgp/src/serialize/mod.rs b/openpgp/src/serialize/mod.rs
index 51cb8311..1f27b50f 100644
--- a/openpgp/src/serialize/mod.rs
+++ b/openpgp/src/serialize/mod.rs
@@ -1077,8 +1077,8 @@ impl Serialize for SubpacketValue {
                 _ => return Err(Error::InvalidArgument(
                     "Unknown kind of fingerprint".into()).into()),
             }
-            Unknown(ref raw) =>
-                o.write_all(raw)?,
+            Unknown { body, .. } =>
+                o.write_all(body)?,
         }
         Ok(())
     }
@@ -1120,7 +1120,7 @@ impl SerializeInto for SubpacketValue {
                 Fingerprint::V4(_) => 1 + fp.serialized_len(),
                 _ => 0,
             },
-            Unknown(ref raw) => raw.len(),
+            Unknown { body, .. } => body.len(),
         }
     }