1 files changed, 336 insertions, 0 deletions
diff --git a/adenosine-pds/src/mst.rs b/adenosine-pds/src/mst.rs
new file mode 100644
index 0000000..a2a394f
--- /dev/null
+++ b/adenosine-pds/src/mst.rs
@@ -0,0 +1,336 @@
+use anyhow::{anyhow, Result};
+use ipfs_sqlite_block_store::BlockStore;
+use libipld::cbor::DagCborCodec;
+use libipld::multihash::Code;
+use libipld::prelude::Codec;
+use libipld::store::DefaultParams;
+use libipld::Block;
+use libipld::{Cid, DagCbor};
+use log::{debug, error, info};
+use std::collections::BTreeMap;
+use std::path::PathBuf;
+use crate::load_car_to_blockstore;
+
+#[derive(Debug, DagCbor, PartialEq, Eq)]
+struct CommitNode {
+    root: Cid,
+    sig: Box<[u8]>,
+}
+
+#[derive(Debug, DagCbor, PartialEq, Eq)]
+struct RootNode {
+    auth_token: Option<String>,
+    prev: Option<Cid>,
+    // TODO: not 'metadata'?
+    meta: Cid,
+    data: Cid,
+}
+
+#[derive(Debug, DagCbor, PartialEq, Eq)]
+struct MetadataNode {
+    datastore: String, // "mst"
+    did: String,
+    version: u8, // 1
+}
+
+#[derive(Debug, DagCbor, PartialEq, Eq)]
+struct MstEntry {
+    k: String,
+    p: u32,
+    v: Cid,
+    t: Option<Cid>,
+}
+
+#[derive(Debug, DagCbor, PartialEq)]
+struct MstNode {
+    l: Option<Cid>,
+    e: Vec<MstEntry>,
+}
+
+struct WipEntry {
+    height: u8,
+    key: String,
+    val: Cid,
+    right: Option<Box<WipNode>>,
+}
+
+struct WipNode {
+    height: u8,
+    left: Option<Box<WipNode>>,
+    entries: Vec<WipEntry>,
+}
+
+fn get_mst_node(db: &mut BlockStore<libipld::DefaultParams>, cid: &Cid) -> Result<MstNode> {
+    let mst_node: MstNode = DagCborCodec.decode(
+        &db.get_block(cid)?
+            .ok_or(anyhow!("expected block in store"))?,
+    )?;
+    Ok(mst_node)
+}
+
+fn print_mst_keys(db: &mut BlockStore<libipld::DefaultParams>, cid: &Cid) -> Result<()> {
+    let node = get_mst_node(db, cid)?;
+    if let Some(ref left) = node.l {
+        print_mst_keys(db, left)?;
+    }
+    let mut key: String = "".to_string();
+    for entry in node.e.iter() {
+        key = format!("{}{}", &key[0..entry.p as usize], entry.k);
+        println!("{}\t-> {}", key, entry.v);
+        if let Some(ref right) = entry.t {
+            print_mst_keys(db, right)?;
+        }
+    }
+    Ok(())
+}
+
+pub fn dump_mst_keys(db_path: &PathBuf) -> Result<()> {
+    let mut db: BlockStore<libipld::DefaultParams> =
+        { BlockStore::open(db_path, Default::default())? };
+
+    let all_aliases: Vec<(Vec<u8>, Cid)> = db.aliases()?;
+    if all_aliases.is_empty() {
+        error!("expected at least one alias in block store");
+        std::process::exit(-1);
+    }
+    let (alias, commit_cid) = all_aliases[0].clone();
+    info!(
+        "starting from {} [{}]",
+        commit_cid,
+        String::from_utf8_lossy(&alias)
+    );
+
+    // NOTE: the faster way to develop would have been to decode to libipld::ipld::Ipld first? meh
+
+    debug!(
+        "raw commit: {:?}",
+        &db.get_block(&commit_cid)?
+            .ok_or(anyhow!("expected commit block in store"))?
+    );
+    let commit: CommitNode = DagCborCodec.decode(
+        &db.get_block(&commit_cid)?
+            .ok_or(anyhow!("expected commit block in store"))?,
+    )?;
+    debug!("Commit: {:?}", commit);
+    let root: RootNode = DagCborCodec.decode(
+        &db.get_block(&commit.root)?
+            .ok_or(anyhow!("expected root block in store"))?,
+    )?;
+    debug!("Root: {:?}", root);
+    let metadata: MetadataNode = DagCborCodec.decode(
+        &db.get_block(&root.meta)?
+            .ok_or(anyhow!("expected metadata block in store"))?,
+    )?;
+    debug!("Metadata: {:?}", metadata);
+    let mst_node: MstNode = DagCborCodec.decode(
+        &db.get_block(&root.data)?
+            .ok_or(anyhow!("expected block in store"))?,
+    )?;
+    debug!("MST root node: {:?}", mst_node);
+    debug!("============");
+
+    print_mst_keys(&mut db, &root.data)?;
+    Ok(())
+}
+
+fn collect_mst_keys(
+    db: &mut BlockStore<libipld::DefaultParams>,
+    cid: &Cid,
+    map: &mut BTreeMap<String, Cid>,
+) -> Result<()> {
+    let node = get_mst_node(db, cid)?;
+    if let Some(ref left) = node.l {
+        collect_mst_keys(db, left, map)?;
+    }
+    let mut key: String = "".to_string();
+    for entry in node.e.iter() {
+        key = format!("{}{}", &key[0..entry.p as usize], entry.k);
+        map.insert(key.clone(), entry.v);
+        if let Some(ref right) = entry.t {
+            collect_mst_keys(db, right, map)?;
+        }
+    }
+    Ok(())
+}
+
+fn leading_zeros(key: &str) -> u8 {
+    let digest = sha256::digest(key);
+    let digest = digest.as_bytes();
+    for i in 0..digest.len() {
+        if digest[i] != '0' as u8 {
+            return i as u8;
+        }
+    }
+    digest.len() as u8
+}
+
+fn generate_mst(
+    db: &mut BlockStore<libipld::DefaultParams>,
+    map: &mut BTreeMap<String, Cid>,
+) -> Result<Cid> {
+    // construct a "WIP" tree
+    let mut root: Option<WipNode> = None;
+    for (key, val) in map {
+        let height = leading_zeros(key);
+        let entry = WipEntry {
+            height,
+            key: key.clone(),
+            val: val.clone(),
+            right: None,
+        };
+        if let Some(node) = root {
+            root = Some(insert_entry(node, entry));
+        } else {
+            root = Some(WipNode {
+                height: entry.height,
+                left: None,
+                entries: vec![entry],
+            });
+        }
+    }
+    serialize_wip_tree(db, root.expect("non-empty MST tree"))
+}
+
+fn insert_entry(mut node: WipNode, entry: WipEntry) -> WipNode {
+    // if we are higher on tree than existing node, replace it with new layer first
+    if entry.height > node.height {
+        node = WipNode {
+            height: entry.height,
+            left: Some(Box::new(node)),
+            entries: vec![],
+        }
+    };
+    // if we are lower on tree, then need to descend first
+    if entry.height < node.height {
+        // we should never be lower down the left than an existing node, and always to the right
+        let mut last = node.entries.pop().expect("hit empty existing entry list");
+        assert!(entry.key > last.key);
+        if last.right.is_some() {
+            last.right = Some(Box::new(insert_entry(*last.right.unwrap(), entry)));
+        } else {
+            last.right = Some(Box::new(WipNode {
+                height: entry.height,
+                left: None,
+                entries: vec![entry],
+            }));
+        }
+        node.entries.push(last);
+        return node;
+    }
+    // same height, simply append to end (but verify first)
+    assert!(node.height == entry.height);
+    if !node.entries.is_empty() {
+        let last = &node.entries.last().unwrap();
+        assert!(entry.key > last.key);
+    }
+    node.entries.push(entry);
+    node
+}
+
+/// returns the length of common characters between the two strings. Strings must be simple ASCII,
+/// which should hold for current ATP MST keys (collection plus TID)
+fn common_prefix_len(a: &str, b: &str) -> usize {
+    let a = a.as_bytes();
+    let b = b.as_bytes();
+    for i in 0..std::cmp::min(a.len(), b.len()) {
+        if a[i] != b[i] {
+            return i;
+        }
+    }
+    // strings are the same, up to common length
+    std::cmp::min(a.len(), b.len())
+}
+
+#[test]
+fn test_common_prefix_len() {
+    assert_eq!(common_prefix_len("abc", "abc"), 3);
+    assert_eq!(common_prefix_len("abcde", "abc"), 3);
+    assert_eq!(common_prefix_len("abcde", "abb"), 2);
+    assert_eq!(common_prefix_len("", "asdf"), 0);
+}
+
+fn serialize_wip_tree(
+    db: &mut BlockStore<libipld::DefaultParams>,
+    wip_node: WipNode,
+) -> Result<Cid> {
+    let left: Option<Cid> = if let Some(left) = wip_node.left {
+        Some(serialize_wip_tree(db, *left)?)
+    } else {
+        None
+    };
+
+    let mut entries: Vec<MstEntry> = vec![];
+    let mut last_key = "".to_string();
+    for wip_entry in wip_node.entries {
+        let right: Option<Cid> = if let Some(right) = wip_entry.right {
+            Some(serialize_wip_tree(db, *right)?)
+        } else {
+            None
+        };
+        let prefix_len = common_prefix_len(&last_key, &wip_entry.key);
+        entries.push(MstEntry {
+            k: wip_entry.key[prefix_len..].to_string(),
+            p: prefix_len as u32,
+            v: wip_entry.val,
+            t: right,
+        });
+        last_key = wip_entry.key;
+    }
+    let mst_node = MstNode {
+        l: left,
+        e: entries,
+    };
+    let block = Block::<DefaultParams>::encode(DagCborCodec, Code::Sha2_256, &mst_node)?;
+    let cid = block.cid().clone();
+    db.put_block(block, None)?;
+    Ok(cid)
+}
+
+pub fn repro_mst(car_path: &PathBuf) -> Result<()> {
+
+    // open a temp block store
+    let mut db: BlockStore<libipld::DefaultParams> = {
+        BlockStore::open_path(ipfs_sqlite_block_store::DbPath::Memory, Default::default())?
+    };
+
+    // load CAR contents from file
+    load_car_to_blockstore(&mut db, car_path)?;
+
+    let all_aliases: Vec<(Vec<u8>, Cid)> = db.aliases()?;
+    if all_aliases.is_empty() {
+        error!("expected at least one alias in block store");
+        std::process::exit(-1);
+    }
+    let (_alias, commit_cid) = all_aliases[0].clone();
+
+    let commit_node: CommitNode = DagCborCodec.decode(
+        &db.get_block(&commit_cid)?
+            .ok_or(anyhow!("expected commit block in store"))?,
+    )?;
+    let root_node: RootNode = DagCborCodec.decode(
+        &db.get_block(&commit_node.root)?
+            .ok_or(anyhow!("expected root block in store"))?,
+    )?;
+    let _metadata_node: MetadataNode = DagCborCodec.decode(
+        &db.get_block(&root_node.meta)?
+            .ok_or(anyhow!("expected metadata block in store"))?,
+    )?;
+
+    // collect key/value sorted map of string/cid, as BTree
+    let mut repo_map: BTreeMap<String, Cid> = BTreeMap::new();
+    collect_mst_keys(&mut db, &root_node.data, &mut repo_map)?;
+
+    // now re-generate nodes
+    let updated = generate_mst(&mut db, &mut repo_map)?;
+
+    info!("original root: {}", root_node.data);
+    info!("regenerated  : {}", updated);
+    if root_node.data == updated {
+        Ok(())
+    } else {
+        println!("FAILED");
+        let a = get_mst_node(&mut db, &root_node.data)?;
+        let b = get_mst_node(&mut db, &updated)?;
+        Err(anyhow!("FAILED to reproduce MST: {:?} != {:?}", a, b))
+    }
+}