update concord backend

2026-09-16 17:35:33 +07:00
parent 66f75ad105
commit d926c1e3ea
8 changed files with 929 additions and 31 deletions
@@ -0,0 +1,392 @@
+use std::collections::BTreeMap;
+use std::fmt;
+
+use data_encoding::HEXLOWER;
+use nostr_sdk::prelude::{EventId, PublicKey, Tag, UnsignedEvent};
+use sha2::{Digest, Sha256};
+
+use crate::decode_hex_32;
+use crate::stream::build_rumor_secs;
+
+pub const KIND_CONTROL: u16 = 3308;
+
+const EDITION_LABEL: &[u8] = b"vector-community/v1/edition";
+
+/// Entity types an edition can address (CORD-02 Appendix B).
+pub mod vsk {
+    pub const COMMUNITY_METADATA: &str = "0";
+    pub const ROLE: &str = "1";
+    pub const CHANNEL_METADATA: &str = "2";
+    pub const GRANT: &str = "3";
+    pub const BANLIST: &str = "4";
+    pub const INVITE_LIVE: &str = "6";
+    pub const INVITE_LINKS: &str = "8";
+    pub const INVITE_REVOKED: &str = "9";
+    pub const DISSOLVED: &str = "10";
+    pub const PINS: &str = "11";
+}
+
+const TAG_SUBKIND: &str = "vsk";
+const TAG_ENTITY: &str = "eid";
+const TAG_VERSION: &str = "ev";
+const TAG_PREV: &str = "ep";
+const TAG_CITATION: &str = "vac";
+
+#[derive(Debug)]
+pub enum EditionError {
+    BadKind(u16),
+    BadField(&'static str),
+    Duplicate(&'static str),
+    Missing(&'static str),
+}
+
+impl fmt::Display for EditionError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            EditionError::BadKind(kind) => write!(f, "not an edition kind: {kind}"),
+            EditionError::BadField(name) => write!(f, "malformed edition field: {name}"),
+            EditionError::Duplicate(name) => write!(f, "duplicate edition field: {name}"),
+            EditionError::Missing(name) => write!(f, "missing edition field: {name}"),
+        }
+    }
+}
+
+impl std::error::Error for EditionError {}
+
+/// A `vac` citation: the Grant edition an actor claims rank under, pinned by
+/// coordinate, version and hash. It is a sync floor, not the verdict.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct AuthorityCitation {
+    pub entity: [u8; 32],
+    pub version: u64,
+    pub hash: [u8; 32],
+}
+
+#[derive(Debug, Clone)]
+pub struct ParsedEdition {
+    pub author: PublicKey,
+    pub subkind: String,
+    pub entity: [u8; 32],
+    pub version: u64,
+    pub prev: Option<[u8; 32]>,
+    pub citation: Option<AuthorityCitation>,
+    pub content: String,
+    pub self_hash: [u8; 32],
+    pub rumor_id: EventId,
+}
+
+pub struct EditionFields<'a> {
+    pub author: PublicKey,
+    pub subkind: &'a str,
+    pub entity: [u8; 32],
+    pub version: u64,
+    pub prev: Option<[u8; 32]>,
+    pub citation: Option<AuthorityCitation>,
+    pub content: &'a str,
+    pub at_secs: u64,
+}
+
+fn signing_bytes(
+    entity: &[u8; 32],
+    version: u64,
+    prev: Option<&[u8; 32]>,
+    content: &[u8],
+) -> Vec<u8> {
+    let mut bytes =
+        Vec::with_capacity(8 + EDITION_LABEL.len() + 32 + 8 + 1 + 32 + 8 + content.len());
+
+    bytes.extend_from_slice(&(EDITION_LABEL.len() as u64).to_be_bytes());
+    bytes.extend_from_slice(EDITION_LABEL);
+    bytes.extend_from_slice(entity);
+    bytes.extend_from_slice(&version.to_be_bytes());
+
+    match prev {
+        Some(prev) => {
+            bytes.push(1);
+            bytes.extend_from_slice(prev);
+        }
+        None => {
+            bytes.push(0);
+            bytes.extend_from_slice(&[0u8; 32]);
+        }
+    }
+
+    bytes.extend_from_slice(&(content.len() as u64).to_be_bytes());
+    bytes.extend_from_slice(content);
+    bytes
+}
+
+pub fn edition_hash(
+    entity: &[u8; 32],
+    version: u64,
+    prev: Option<&[u8; 32]>,
+    content: &[u8],
+) -> [u8; 32] {
+    Sha256::digest(signing_bytes(entity, version, prev, content)).into()
+}
+
+pub fn build_edition(fields: EditionFields<'_>) -> UnsignedEvent {
+    let mut tags = vec![
+        Tag::custom(TAG_SUBKIND, [fields.subkind]),
+        Tag::custom(TAG_ENTITY, [HEXLOWER.encode(&fields.entity)]),
+        Tag::custom(TAG_VERSION, [fields.version.to_string()]),
+    ];
+
+    if let Some(prev) = fields.prev {
+        tags.push(Tag::custom(TAG_PREV, [HEXLOWER.encode(&prev)]));
+    }
+
+    if let Some(citation) = fields.citation {
+        tags.push(Tag::custom(
+            TAG_CITATION,
+            [
+                HEXLOWER.encode(&citation.entity),
+                citation.version.to_string(),
+                HEXLOWER.encode(&citation.hash),
+            ],
+        ));
+    }
+
+    build_rumor_secs(
+        KIND_CONTROL,
+        fields.author,
+        fields.content,
+        tags,
+        fields.at_secs,
+    )
+}
+
+pub fn parse_edition(rumor: &UnsignedEvent) -> Result<ParsedEdition, EditionError> {
+    let kind = rumor.kind.as_u16();
+
+    if kind != KIND_CONTROL {
+        return Err(EditionError::BadKind(kind));
+    }
+
+    let subkind = value(rumor, TAG_SUBKIND)?
+        .ok_or(EditionError::Missing(TAG_SUBKIND))?
+        .to_owned();
+
+    if canonical_decimal(&subkind).is_none() {
+        return Err(EditionError::BadField(TAG_SUBKIND));
+    }
+
+    let entity = hex32(
+        value(rumor, TAG_ENTITY)?.ok_or(EditionError::Missing(TAG_ENTITY))?,
+        TAG_ENTITY,
+    )?;
+
+    let version =
+        canonical_decimal(value(rumor, TAG_VERSION)?.ok_or(EditionError::Missing(TAG_VERSION))?)
+            .ok_or(EditionError::BadField(TAG_VERSION))?;
+
+    let prev = match value(rumor, TAG_PREV)? {
+        Some(raw) => Some(hex32(raw, TAG_PREV)?),
+        None => None,
+    };
+
+    let citation = match fields(rumor, TAG_CITATION)? {
+        Some(fields) if fields.len() == 4 => Some(AuthorityCitation {
+            entity: hex32(&fields[1], TAG_CITATION)?,
+            version: canonical_decimal(&fields[2]).ok_or(EditionError::BadField(TAG_CITATION))?,
+            hash: hex32(&fields[3], TAG_CITATION)?,
+        }),
+        Some(_) => return Err(EditionError::BadField(TAG_CITATION)),
+        None => None,
+    };
+
+    let self_hash = edition_hash(&entity, version, prev.as_ref(), rumor.content.as_bytes());
+
+    Ok(ParsedEdition {
+        author: rumor.pubkey,
+        subkind,
+        entity,
+        version,
+        prev,
+        citation,
+        content: rumor.content.clone(),
+        self_hash,
+        rumor_id: rumor.id.unwrap_or_else(|| rumor.compute_id()),
+    })
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct EditionMeta {
+    pub version: u64,
+    pub self_hash: [u8; 32],
+    pub prev: Option<[u8; 32]>,
+    pub tiebreak_id: EventId,
+}
+
+impl From<&ParsedEdition> for EditionMeta {
+    fn from(edition: &ParsedEdition) -> Self {
+        Self {
+            version: edition.version,
+            self_hash: edition.self_hash,
+            prev: edition.prev,
+            tiebreak_id: edition.rumor_id,
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
+pub struct FoldResult {
+    pub head: Option<usize>,
+    pub gap: bool,
+    pub anchored: bool,
+}
+
+/// The highest version whose chain is intact, given a held floor.
+pub fn fold(editions: &[EditionMeta], floor: u64, floor_hash: Option<&[u8; 32]>) -> FoldResult {
+    let mut by_version: BTreeMap<u64, usize> = BTreeMap::new();
+
+    for (index, edition) in editions.iter().enumerate() {
+        if edition.version < floor {
+            continue;
+        }
+
+        match by_version.get(&edition.version) {
+            Some(&current) if editions[current].tiebreak_id <= edition.tiebreak_id => {}
+            _ => {
+                by_version.insert(edition.version, index);
+            }
+        }
+    }
+
+    let Some((&lowest_version, &lowest_index)) = by_version.first_key_value() else {
+        return FoldResult::default();
+    };
+
+    let lowest = editions[lowest_index];
+
+    let anchored = if floor == 0 {
+        lowest_version == 1 && lowest.prev.is_none()
+    } else if lowest_version == floor {
+        floor_hash == Some(&lowest.self_hash)
+    } else if lowest_version == floor + 1 {
+        floor_hash.is_some() && lowest.prev.as_ref() == floor_hash
+    } else {
+        false
+    };
+
+    let mut head = Some(lowest_index);
+    let mut gap = !anchored;
+    let mut previous_version = lowest_version;
+    let mut previous_hash = lowest.self_hash;
+
+    for (&version, &index) in by_version.range(lowest_version + 1..) {
+        let edition = editions[index];
+
+        if version == previous_version + 1 && edition.prev == Some(previous_hash) {
+            head = Some(index);
+            previous_version = version;
+            previous_hash = edition.self_hash;
+        } else {
+            gap = true;
+            break;
+        }
+    }
+
+    FoldResult {
+        head,
+        gap,
+        anchored,
+    }
+}
+
+/// The highest version overall, ignoring contiguity.
+pub fn bootstrap_head(editions: &[EditionMeta]) -> Option<usize> {
+    editions
+        .iter()
+        .enumerate()
+        .reduce(|(best_index, best), (index, candidate)| {
+            let supersedes = candidate.version > best.version
+                || (candidate.version == best.version && candidate.tiebreak_id < best.tiebreak_id);
+
+            if supersedes {
+                (index, candidate)
+            } else {
+                (best_index, best)
+            }
+        })
+        .map(|(index, _)| index)
+}
+
+fn canonical_decimal(raw: &str) -> Option<u64> {
+    if raw.is_empty() || !raw.bytes().all(|byte| byte.is_ascii_digit()) {
+        return None;
+    }
+
+    if raw.len() > 1 && raw.starts_with('0') {
+        return None;
+    }
+
+    raw.parse().ok()
+}
+
+fn hex32(raw: &str, name: &'static str) -> Result<[u8; 32], EditionError> {
+    decode_hex_32(raw).map_err(|_| EditionError::BadField(name))
+}
+
+fn fields<'a>(
+    rumor: &'a UnsignedEvent,
+    name: &'static str,
+) -> Result<Option<&'a [String]>, EditionError> {
+    let mut found: Option<&[String]> = None;
+
+    for tag in rumor.tags.iter() {
+        let tag_fields = tag.as_slice();
+
+        if tag_fields.first().map(String::as_str) != Some(name) {
+            continue;
+        }
+
+        if found.is_some() {
+            return Err(EditionError::Duplicate(name));
+        }
+
+        found = Some(tag_fields);
+    }
+
+    Ok(found)
+}
+
+fn value<'a>(
+    rumor: &'a UnsignedEvent,
+    name: &'static str,
+) -> Result<Option<&'a str>, EditionError> {
+    match fields(rumor, name)? {
+        Some(fields) if fields.len() == 2 => Ok(Some(fields[1].as_str())),
+        Some(_) => Err(EditionError::BadField(name)),
+        None => Ok(None),
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn edition_hash_matches_the_cross_client_vector() {
+        let entity = [0x11u8; 32];
+
+        assert_eq!(
+            HEXLOWER.encode(&edition_hash(&entity, 1, None, b"hello")),
+            "2daf42e65a6bc259a4c99fac6df754a5d3d92310607cf13e2a1e8c94d42f6303"
+        );
+
+        // The golden vector only exercises the absent-prev encoding; pin the
+        // present-prev branch structurally so a swapped flag stays visible.
+        let bytes = signing_bytes(&entity, 1, Some(&entity), b"hello");
+        assert_eq!(
+            bytes.len(),
+            8 + EDITION_LABEL.len() + 32 + 8 + 1 + 32 + 8 + 5
+        );
+        assert_eq!(&bytes[8..8 + EDITION_LABEL.len()], EDITION_LABEL);
+        assert_eq!(
+            bytes[8 + EDITION_LABEL.len() + 32..][..8],
+            1u64.to_be_bytes()
+        );
+        assert_eq!(bytes[8 + EDITION_LABEL.len() + 32 + 8], 1);
+    }
+}