chore(tvix/store): move protos into separate mod.rs

This allows adding more stuff into this namespace, from different files.

Also move tests on proto-related code from src/tests to src/proto/tests.

Change-Id: I49e066fce90efbc18e16d68f94497b32ed5625c0
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8091
Reviewed-by: tazjin <tazjin@tvl.su>
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
Tested-by: BuildkiteCI

tvix/store/src/proto/mod.rs

@@ -0,0 +1,353 @@
+#![allow(clippy::derive_partial_eq_without_eq)]
+// https://github.com/hyperium/tonic/issues/1056
+use std::{collections::HashSet, iter::Peekable};
+use thiserror::Error;
+
+use prost::Message;
+
+use nix_compat::store_path::{ParseStorePathError, StorePath};
+
+tonic::include_proto!("tvix.store.v1");
+
+#[cfg(feature = "reflection")]
+/// Compiled file descriptors for implementing [gRPC
+/// reflection](https://github.com/grpc/grpc/blob/master/doc/server-reflection.md) with e.g.
+/// [`tonic_reflection`](https://docs.rs/tonic-reflection).
+pub const FILE_DESCRIPTOR_SET: &[u8] = tonic::include_file_descriptor_set!("tvix.store.v1");
+
+#[cfg(test)]
+mod tests;
+
+/// Errors that can occur during the validation of Directory messages.
+#[derive(Debug, PartialEq, Eq, Error)]
+pub enum ValidateDirectoryError {
+    /// Elements are not in sorted order
+    #[error("{0} is not sorted")]
+    WrongSorting(String),
+    /// Multiple elements with the same name encountered
+    #[error("{0} is a duplicate name")]
+    DuplicateName(String),
+    /// Invalid name encountered
+    #[error("Invalid name in {0}")]
+    InvalidName(String),
+    /// Invalid digest length encountered
+    #[error("Invalid Digest length: {0}")]
+    InvalidDigestLen(usize),
+}
+
+/// Errors that can occur during the validation of PathInfo messages.
+#[derive(Debug, Error, PartialEq)]
+pub enum ValidatePathInfoError {
+    /// No node present
+    #[error("No node present")]
+    NoNodePresent(),
+
+    /// Invalid node name encountered.
+    #[error("Failed to parse {0} as NixPath: {1}")]
+    InvalidNodeName(String, ParseStorePathError),
+
+    /// The digest the (root) node refers to has invalid length.
+    #[error("Invalid Digest length: {0}")]
+    InvalidDigestLen(usize),
+
+    /// The number of references in the narinfo.reference_names field does not match
+    /// the number of references in the .references field.
+    #[error("Inconsistent Number of References: {0} (references) vs {0} (narinfo)")]
+    InconsistentNumberOfReferences(usize, usize),
+}
+
+/// Checks a Node name for validity as an intermediate node, and returns an
+/// error that's generated from the supplied constructor.
+///
+/// We disallow slashes, null bytes, '.', '..' and the empty string.
+fn validate_node_name<E>(name: &str, err: fn(String) -> E) -> Result<(), E> {
+    if name.is_empty() || name == ".." || name == "." || name.contains('\x00') || name.contains('/')
+    {
+        return Err(err(name.to_string()));
+    }
+    Ok(())
+}
+
+/// Checks a digest for validity.
+/// Digests are 32 bytes long, as we store blake3 digests.
+fn validate_digest<E>(digest: &Vec<u8>, err: fn(usize) -> E) -> Result<(), E> {
+    if digest.len() != 32 {
+        return Err(err(digest.len()));
+    }
+    Ok(())
+}
+
+/// Parses a root node name.
+///
+/// On success, this returns the parsed [StorePath].
+/// On error, it returns an error generated from the supplied constructor.
+fn parse_node_name_root<E>(
+    name: &str,
+    err: fn(String, ParseStorePathError) -> E,
+) -> Result<StorePath, E> {
+    match StorePath::from_string(name) {
+        Ok(np) => Ok(np),
+        Err(e) => Err(err(name.to_string(), e)),
+    }
+}
+
+impl PathInfo {
+    /// validate performs some checks on the PathInfo struct,
+    /// Returning either a [StorePath] of the root node, or a
+    /// [ValidatePathInfoError].
+    pub fn validate(&self) -> Result<StorePath, ValidatePathInfoError> {
+        // If there is a narinfo field populated, ensure the number of references there
+        // matches PathInfo.references count.
+        if let Some(narinfo) = &self.narinfo {
+            if narinfo.reference_names.len() != self.references.len() {
+                return Err(ValidatePathInfoError::InconsistentNumberOfReferences(
+                    narinfo.reference_names.len(),
+                    self.references.len(),
+                ));
+            }
+        }
+        // FUTUREWORK: parse references in reference_names. ensure they start
+        // with storeDir, and use the same digest as in self.references.
+
+        // Ensure there is a (root) node present, and it properly parses to a [StorePath].
+        let root_nix_path = match &self.node {
+            None => {
+                return Err(ValidatePathInfoError::NoNodePresent());
+            }
+            Some(Node { node }) => match node {
+                None => {
+                    return Err(ValidatePathInfoError::NoNodePresent());
+                }
+                Some(node::Node::Directory(directory_node)) => {
+                    // ensure the digest has the appropriate size.
+                    validate_digest(
+                        &directory_node.digest,
+                        ValidatePathInfoError::InvalidDigestLen,
+                    )?;
+
+                    // parse the name
+                    parse_node_name_root(
+                        &directory_node.name,
+                        ValidatePathInfoError::InvalidNodeName,
+                    )?
+                }
+                Some(node::Node::File(file_node)) => {
+                    // ensure the digest has the appropriate size.
+                    validate_digest(&file_node.digest, ValidatePathInfoError::InvalidDigestLen)?;
+
+                    // parse the name
+                    parse_node_name_root(&file_node.name, ValidatePathInfoError::InvalidNodeName)?
+                }
+                Some(node::Node::Symlink(symlink_node)) => {
+                    // parse the name
+                    parse_node_name_root(
+                        &symlink_node.name,
+                        ValidatePathInfoError::InvalidNodeName,
+                    )?
+                }
+            },
+        };
+
+        // return the root nix path
+        Ok(root_nix_path)
+    }
+}
+
+/// NamedNode is implemented for [FileNode], [DirectoryNode] and [SymlinkNode]
+/// and [node::Node], so we can ask all of them for the name easily.
+pub trait NamedNode {
+    fn get_name(&self) -> &str;
+}
+
+impl NamedNode for &FileNode {
+    fn get_name(&self) -> &str {
+        self.name.as_str()
+    }
+}
+
+impl NamedNode for &DirectoryNode {
+    fn get_name(&self) -> &str {
+        self.name.as_str()
+    }
+}
+
+impl NamedNode for &SymlinkNode {
+    fn get_name(&self) -> &str {
+        self.name.as_str()
+    }
+}
+
+impl NamedNode for node::Node {
+    fn get_name(&self) -> &str {
+        match self {
+            node::Node::File(node_file) => &node_file.name,
+            node::Node::Directory(node_directory) => &node_directory.name,
+            node::Node::Symlink(node_symlink) => &node_symlink.name,
+        }
+    }
+}
+
+/// Accepts a name, and a mutable reference to the previous name.
+/// If the passed name is larger than the previous one, the reference is updated.
+/// If it's not, an error is returned.
+fn update_if_lt_prev<'set, 'n>(
+    prev_name: &'set mut &'n str,
+    name: &'n str,
+) -> Result<(), ValidateDirectoryError> {
+    if *name < **prev_name {
+        return Err(ValidateDirectoryError::WrongSorting(name.to_string()));
+    }
+    *prev_name = name;
+    Ok(())
+}
+
+/// Inserts the given name into a HashSet if it's not already in there.
+/// If it is, an error is returned.
+fn insert_once<'n>(
+    seen_names: &mut HashSet<&'n str>,
+    name: &'n str,
+) -> Result<(), ValidateDirectoryError> {
+    if seen_names.get(name).is_some() {
+        return Err(ValidateDirectoryError::DuplicateName(name.to_string()));
+    }
+    seen_names.insert(name);
+    Ok(())
+}
+
+impl Directory {
+    /// The size of a directory is the number of all regular and symlink elements,
+    /// the number of directory elements, and their size fields.
+    pub fn size(&self) -> u32 {
+        self.files.len() as u32
+            + self.symlinks.len() as u32
+            + self
+                .directories
+                .iter()
+                .fold(0, |acc: u32, e| (acc + 1 + e.size))
+    }
+
+    /// Calculates the digest of a Directory, which is the blake3 hash of a
+    /// Directory protobuf message, serialized in protobuf canonical form.
+    pub fn digest(&self) -> Vec<u8> {
+        let mut hasher = blake3::Hasher::new();
+
+        hasher.update(&self.encode_to_vec()).finalize().as_bytes()[..].to_vec()
+    }
+
+    /// validate checks the directory for invalid data, such as:
+    /// - violations of name restrictions
+    /// - invalid digest lengths
+    /// - not properly sorted lists
+    /// - duplicate names in the three lists
+    pub fn validate(&self) -> Result<(), ValidateDirectoryError> {
+        let mut seen_names: HashSet<&str> = HashSet::new();
+
+        let mut last_directory_name: &str = "";
+        let mut last_file_name: &str = "";
+        let mut last_symlink_name: &str = "";
+
+        // check directories
+        for directory_node in &self.directories {
+            validate_node_name(&directory_node.name, ValidateDirectoryError::InvalidName)?;
+            validate_digest(
+                &directory_node.digest,
+                ValidateDirectoryError::InvalidDigestLen,
+            )?;
+
+            update_if_lt_prev(&mut last_directory_name, directory_node.name.as_str())?;
+            insert_once(&mut seen_names, directory_node.name.as_str())?;
+        }
+
+        // check files
+        for file_node in &self.files {
+            validate_node_name(&file_node.name, ValidateDirectoryError::InvalidName)?;
+            validate_digest(&file_node.digest, ValidateDirectoryError::InvalidDigestLen)?;
+
+            update_if_lt_prev(&mut last_file_name, file_node.name.as_str())?;
+            insert_once(&mut seen_names, file_node.name.as_str())?;
+        }
+
+        // check symlinks
+        for symlink_node in &self.symlinks {
+            validate_node_name(&symlink_node.name, ValidateDirectoryError::InvalidName)?;
+
+            update_if_lt_prev(&mut last_symlink_name, symlink_node.name.as_str())?;
+            insert_once(&mut seen_names, symlink_node.name.as_str())?;
+        }
+
+        Ok(())
+    }
+
+    /// Allows iterating over all three nodes ([DirectoryNode], [FileNode],
+    /// [SymlinkNode]) in an ordered fashion, as long as the individual lists
+    /// are sorted (which can be checked by the [Directory::validate]).
+    pub fn nodes(&self) -> DirectoryNodesIterator {
+        return DirectoryNodesIterator {
+            i_directories: self.directories.iter().peekable(),
+            i_files: self.files.iter().peekable(),
+            i_symlinks: self.symlinks.iter().peekable(),
+        };
+    }
+}
+
+/// Struct to hold the state of an iterator over all nodes of a Directory.
+///
+/// Internally, this keeps peekable Iterators over all three lists of a
+/// Directory message.
+pub struct DirectoryNodesIterator<'a> {
+    // directory: &Directory,
+    i_directories: Peekable<std::slice::Iter<'a, DirectoryNode>>,
+    i_files: Peekable<std::slice::Iter<'a, FileNode>>,
+    i_symlinks: Peekable<std::slice::Iter<'a, SymlinkNode>>,
+}
+
+/// looks at two elements implementing NamedNode, and returns true if "left
+/// is smaller / comes first".
+///
+/// Some(_) is preferred over None.
+fn left_name_lt_right<A: NamedNode, B: NamedNode>(left: Option<&A>, right: Option<&B>) -> bool {
+    match left {
+        // if left is None, right always wins
+        None => false,
+        Some(left_inner) => {
+            // left is Some.
+            match right {
+                // left is Some, right is None - left wins.
+                None => true,
+                Some(right_inner) => {
+                    // both are Some - compare the name.
+                    return left_inner.get_name() < right_inner.get_name();
+                }
+            }
+        }
+    }
+}
+
+impl Iterator for DirectoryNodesIterator<'_> {
+    type Item = node::Node;
+
+    // next returns the next node in the Directory.
+    // we peek at all three internal iterators, and pick the one with the
+    // smallest name, to ensure lexicographical ordering.
+    // The individual lists are already known to be sorted.
+    fn next(&mut self) -> Option<Self::Item> {
+        if left_name_lt_right(self.i_directories.peek(), self.i_files.peek()) {
+            // i_directories is still in the game, compare with symlinks
+            if left_name_lt_right(self.i_directories.peek(), self.i_symlinks.peek()) {
+                self.i_directories
+                    .next()
+                    .cloned()
+                    .map(node::Node::Directory)
+            } else {
+                self.i_symlinks.next().cloned().map(node::Node::Symlink)
+            }
+        } else {
+            // i_files is still in the game, compare with symlinks
+            if left_name_lt_right(self.i_files.peek(), self.i_symlinks.peek()) {
+                self.i_files.next().cloned().map(node::Node::File)
+            } else {
+                self.i_symlinks.next().cloned().map(node::Node::Symlink)
+            }
+        }
+    }
+}

tvix/store/src/proto/tests/directory.rs

@@ -0,0 +1,285 @@
+use crate::proto::{Directory, DirectoryNode, FileNode, SymlinkNode, ValidateDirectoryError};
+use lazy_static::lazy_static;
+
+lazy_static! {
+    static ref DUMMY_DIGEST: Vec<u8> = vec![
+        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+        0x00, 0x00,
+    ];
+}
+#[test]
+fn size() {
+    {
+        let d = Directory::default();
+        assert_eq!(d.size(), 0);
+    }
+    {
+        let d = Directory {
+            directories: vec![DirectoryNode {
+                name: String::from("foo"),
+                digest: DUMMY_DIGEST.to_vec(),
+                size: 0,
+            }],
+            ..Default::default()
+        };
+        assert_eq!(d.size(), 1);
+    }
+    {
+        let d = Directory {
+            directories: vec![DirectoryNode {
+                name: String::from("foo"),
+                digest: DUMMY_DIGEST.to_vec(),
+                size: 4,
+            }],
+            ..Default::default()
+        };
+        assert_eq!(d.size(), 5);
+    }
+    {
+        let d = Directory {
+            files: vec![FileNode {
+                name: String::from("foo"),
+                digest: DUMMY_DIGEST.to_vec(),
+                size: 42,
+                executable: false,
+            }],
+            ..Default::default()
+        };
+        assert_eq!(d.size(), 1);
+    }
+    {
+        let d = Directory {
+            symlinks: vec![SymlinkNode {
+                name: String::from("foo"),
+                target: String::from("bar"),
+            }],
+            ..Default::default()
+        };
+        assert_eq!(d.size(), 1);
+    }
+}
+
+#[test]
+fn digest() {
+    let d = Directory::default();
+
+    assert_eq!(
+        d.digest(),
+        vec![
+            0xaf, 0x13, 0x49, 0xb9, 0xf5, 0xf9, 0xa1, 0xa6, 0xa0, 0x40, 0x4d, 0xea, 0x36, 0xdc,
+            0xc9, 0x49, 0x9b, 0xcb, 0x25, 0xc9, 0xad, 0xc1, 0x12, 0xb7, 0xcc, 0x9a, 0x93, 0xca,
+            0xe4, 0x1f, 0x32, 0x62
+        ]
+    )
+}
+
+#[test]
+fn validate_empty() {
+    let d = Directory::default();
+    assert_eq!(d.validate(), Ok(()));
+}
+
+#[test]
+fn validate_invalid_names() {
+    {
+        let d = Directory {
+            directories: vec![DirectoryNode {
+                name: "".to_string(),
+                digest: DUMMY_DIGEST.to_vec(),
+                size: 42,
+            }],
+            ..Default::default()
+        };
+        match d.validate().expect_err("must fail") {
+            ValidateDirectoryError::InvalidName(n) => {
+                assert_eq!(n, "")
+            }
+            _ => panic!("unexpected error"),
+        };
+    }
+
+    {
+        let d = Directory {
+            directories: vec![DirectoryNode {
+                name: ".".to_string(),
+                digest: DUMMY_DIGEST.to_vec(),
+                size: 42,
+            }],
+            ..Default::default()
+        };
+        match d.validate().expect_err("must fail") {
+            ValidateDirectoryError::InvalidName(n) => {
+                assert_eq!(n, ".")
+            }
+            _ => panic!("unexpected error"),
+        };
+    }
+
+    {
+        let d = Directory {
+            files: vec![FileNode {
+                name: "..".to_string(),
+                digest: DUMMY_DIGEST.to_vec(),
+                size: 42,
+                executable: false,
+            }],
+            ..Default::default()
+        };
+        match d.validate().expect_err("must fail") {
+            ValidateDirectoryError::InvalidName(n) => {
+                assert_eq!(n, "..")
+            }
+            _ => panic!("unexpected error"),
+        };
+    }
+
+    {
+        let d = Directory {
+            symlinks: vec![SymlinkNode {
+                name: "\x00".to_string(),
+                target: "foo".to_string(),
+            }],
+            ..Default::default()
+        };
+        match d.validate().expect_err("must fail") {
+            ValidateDirectoryError::InvalidName(n) => {
+                assert_eq!(n, "\x00")
+            }
+            _ => panic!("unexpected error"),
+        };
+    }
+
+    {
+        let d = Directory {
+            symlinks: vec![SymlinkNode {
+                name: "foo/bar".to_string(),
+                target: "foo".to_string(),
+            }],
+            ..Default::default()
+        };
+        match d.validate().expect_err("must fail") {
+            ValidateDirectoryError::InvalidName(n) => {
+                assert_eq!(n, "foo/bar")
+            }
+            _ => panic!("unexpected error"),
+        };
+    }
+}
+
+#[test]
+fn validate_invalid_digest() {
+    let d = Directory {
+        directories: vec![DirectoryNode {
+            name: "foo".to_string(),
+            digest: vec![0x00, 0x42], // invalid length
+            size: 42,
+        }],
+        ..Default::default()
+    };
+    match d.validate().expect_err("must fail") {
+        ValidateDirectoryError::InvalidDigestLen(n) => {
+            assert_eq!(n, 2)
+        }
+        _ => panic!("unexpected error"),
+    }
+}
+
+#[test]
+fn validate_sorting() {
+    // "b" comes before "a", bad.
+    {
+        let d = Directory {
+            directories: vec![
+                DirectoryNode {
+                    name: "b".to_string(),
+                    digest: DUMMY_DIGEST.to_vec(),
+                    size: 42,
+                },
+                DirectoryNode {
+                    name: "a".to_string(),
+                    digest: DUMMY_DIGEST.to_vec(),
+                    size: 42,
+                },
+            ],
+            ..Default::default()
+        };
+        match d.validate().expect_err("must fail") {
+            ValidateDirectoryError::WrongSorting(s) => {
+                assert_eq!(s, "a".to_string());
+            }
+            _ => panic!("unexpected error"),
+        }
+    }
+
+    // "a" exists twice, bad.
+    {
+        let d = Directory {
+            directories: vec![
+                DirectoryNode {
+                    name: "a".to_string(),
+                    digest: DUMMY_DIGEST.to_vec(),
+                    size: 42,
+                },
+                DirectoryNode {
+                    name: "a".to_string(),
+                    digest: DUMMY_DIGEST.to_vec(),
+                    size: 42,
+                },
+            ],
+            ..Default::default()
+        };
+        match d.validate().expect_err("must fail") {
+            ValidateDirectoryError::DuplicateName(s) => {
+                assert_eq!(s, "a".to_string());
+            }
+            _ => panic!("unexpected error"),
+        }
+    }
+
+    // "a" comes before "b", all good.
+    {
+        let d = Directory {
+            directories: vec![
+                DirectoryNode {
+                    name: "a".to_string(),
+                    digest: DUMMY_DIGEST.to_vec(),
+                    size: 42,
+                },
+                DirectoryNode {
+                    name: "b".to_string(),
+                    digest: DUMMY_DIGEST.to_vec(),
+                    size: 42,
+                },
+            ],
+            ..Default::default()
+        };
+
+        d.validate().expect("validate shouldn't error");
+    }
+
+    // [b, c] and [a] are both properly sorted.
+    {
+        let d = Directory {
+            directories: vec![
+                DirectoryNode {
+                    name: "b".to_string(),
+                    digest: DUMMY_DIGEST.to_vec(),
+                    size: 42,
+                },
+                DirectoryNode {
+                    name: "c".to_string(),
+                    digest: DUMMY_DIGEST.to_vec(),
+                    size: 42,
+                },
+            ],
+            symlinks: vec![SymlinkNode {
+                name: "a".to_string(),
+                target: "foo".to_string(),
+            }],
+            ..Default::default()
+        };
+
+        d.validate().expect("validate shouldn't error");
+    }
+}

tvix/store/src/proto/tests/directory_nodes_iterator.rs

@@ -0,0 +1,82 @@
+use crate::proto::node::Node;
+use crate::proto::Directory;
+use crate::proto::DirectoryNode;
+use crate::proto::FileNode;
+use crate::proto::SymlinkNode;
+
+#[test]
+fn iterator() -> anyhow::Result<()> {
+    let d = Directory {
+        directories: vec![
+            DirectoryNode {
+                name: "c".to_string(),
+                ..DirectoryNode::default()
+            },
+            DirectoryNode {
+                name: "d".to_string(),
+                ..DirectoryNode::default()
+            },
+            DirectoryNode {
+                name: "h".to_string(),
+                ..DirectoryNode::default()
+            },
+            DirectoryNode {
+                name: "l".to_string(),
+                ..DirectoryNode::default()
+            },
+        ],
+        files: vec![
+            FileNode {
+                name: "b".to_string(),
+                ..FileNode::default()
+            },
+            FileNode {
+                name: "e".to_string(),
+                ..FileNode::default()
+            },
+            FileNode {
+                name: "g".to_string(),
+                ..FileNode::default()
+            },
+            FileNode {
+                name: "j".to_string(),
+                ..FileNode::default()
+            },
+        ],
+        symlinks: vec![
+            SymlinkNode {
+                name: "a".to_string(),
+                ..SymlinkNode::default()
+            },
+            SymlinkNode {
+                name: "f".to_string(),
+                ..SymlinkNode::default()
+            },
+            SymlinkNode {
+                name: "i".to_string(),
+                ..SymlinkNode::default()
+            },
+            SymlinkNode {
+                name: "k".to_string(),
+                ..SymlinkNode::default()
+            },
+        ],
+    };
+
+    let mut node_names: Vec<String> = vec![];
+
+    for node in d.nodes() {
+        match node {
+            Node::Directory(n) => node_names.push(n.name),
+            Node::File(n) => node_names.push(n.name),
+            Node::Symlink(n) => node_names.push(n.name),
+        };
+    }
+
+    assert_eq!(
+        vec!["a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l"],
+        node_names
+    );
+
+    Ok(())
+}

tvix/store/src/proto/tests/mod.rs

@@ -0,0 +1,3 @@
+mod directory;
+mod directory_nodes_iterator;
+mod pathinfo;

tvix/store/src/proto/tests/pathinfo.rs

@@ -0,0 +1,207 @@
+use crate::proto::{self, Node, PathInfo, ValidatePathInfoError};
+use lazy_static::lazy_static;
+use nix_compat::store_path::{ParseStorePathError, StorePath};
+use test_case::test_case;
+
+lazy_static! {
+    static ref DUMMY_DIGEST: Vec<u8> = vec![
+        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+        0x00, 0x00,
+    ];
+    static ref DUMMY_DIGEST_2: Vec<u8> = vec![
+        0x10, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+        0x00, 0x00,
+    ];
+}
+
+const DUMMY_NAME: &str = "00000000000000000000000000000000-dummy";
+
+#[test_case(
+    None,
+    Err(ValidatePathInfoError::NoNodePresent()) ;
+    "No node"
+)]
+#[test_case(
+    Some(Node { node: None }),
+    Err(ValidatePathInfoError::NoNodePresent());
+    "No node 2"
+)]
+fn validate_no_node(
+    t_node: Option<proto::Node>,
+    t_result: Result<StorePath, ValidatePathInfoError>,
+) {
+    // construct the PathInfo object
+    let p = PathInfo {
+        node: t_node,
+        ..Default::default()
+    };
+    assert_eq!(t_result, p.validate());
+}
+
+#[test_case(
+    proto::DirectoryNode {
+        name: DUMMY_NAME.to_string(),
+        digest: DUMMY_DIGEST.to_vec(),
+        size: 0,
+    },
+    Ok(StorePath::from_string(DUMMY_NAME).expect("must succeed"));
+    "ok"
+)]
+#[test_case(
+    proto::DirectoryNode {
+        name: DUMMY_NAME.to_string(),
+        digest: vec![],
+        size: 0,
+    },
+    Err(ValidatePathInfoError::InvalidDigestLen(0));
+    "invalid digest length"
+)]
+#[test_case(
+    proto::DirectoryNode {
+        name: "invalid".to_string(),
+        digest: DUMMY_DIGEST.to_vec(),
+        size: 0,
+    },
+    Err(ValidatePathInfoError::InvalidNodeName(
+        "invalid".to_string(),
+        ParseStorePathError::InvalidName("".to_string())
+    ));
+    "invalid node name"
+)]
+fn validate_directory(
+    t_directory_node: proto::DirectoryNode,
+    t_result: Result<StorePath, ValidatePathInfoError>,
+) {
+    // construct the PathInfo object
+    let p = PathInfo {
+        node: Some(Node {
+            node: Some(proto::node::Node::Directory(t_directory_node)),
+        }),
+        ..Default::default()
+    };
+    assert_eq!(t_result, p.validate());
+}
+
+#[test_case(
+    proto::FileNode {
+        name: DUMMY_NAME.to_string(),
+        digest: DUMMY_DIGEST.to_vec(),
+        size: 0,
+        executable: false,
+    },
+    Ok(StorePath::from_string(DUMMY_NAME).expect("must succeed"));
+    "ok"
+)]
+#[test_case(
+    proto::FileNode {
+        name: DUMMY_NAME.to_string(),
+        digest: vec![],
+        ..Default::default()
+    },
+    Err(ValidatePathInfoError::InvalidDigestLen(0));
+    "invalid digest length"
+)]
+#[test_case(
+    proto::FileNode {
+        name: "invalid".to_string(),
+        digest: DUMMY_DIGEST.to_vec(),
+        ..Default::default()
+    },
+    Err(ValidatePathInfoError::InvalidNodeName(
+        "invalid".to_string(),
+        ParseStorePathError::InvalidName("".to_string())
+    ));
+    "invalid node name"
+)]
+fn validate_file(t_file_node: proto::FileNode, t_result: Result<StorePath, ValidatePathInfoError>) {
+    // construct the PathInfo object
+    let p = PathInfo {
+        node: Some(Node {
+            node: Some(proto::node::Node::File(t_file_node)),
+        }),
+        ..Default::default()
+    };
+    assert_eq!(t_result, p.validate());
+}
+
+#[test_case(
+    proto::SymlinkNode {
+        name: DUMMY_NAME.to_string(),
+        ..Default::default()
+    },
+    Ok(StorePath::from_string(DUMMY_NAME).expect("must succeed"));
+    "ok"
+)]
+#[test_case(
+    proto::SymlinkNode {
+        name: "invalid".to_string(),
+        ..Default::default()
+    },
+    Err(ValidatePathInfoError::InvalidNodeName(
+        "invalid".to_string(),
+        ParseStorePathError::InvalidName("".to_string())
+    ));
+    "invalid node name"
+)]
+fn validate_symlink(
+    t_symlink_node: proto::SymlinkNode,
+    t_result: Result<StorePath, ValidatePathInfoError>,
+) {
+    // construct the PathInfo object
+    let p = PathInfo {
+        node: Some(Node {
+            node: Some(proto::node::Node::Symlink(t_symlink_node)),
+        }),
+        ..Default::default()
+    };
+    assert_eq!(t_result, p.validate());
+}
+
+#[test]
+fn validate_references() {
+    // create a PathInfo without narinfo field.
+    let path_info = PathInfo {
+        node: Some(Node {
+            node: Some(proto::node::Node::Directory(proto::DirectoryNode {
+                name: DUMMY_NAME.to_string(),
+                digest: DUMMY_DIGEST.to_vec(),
+                size: 0,
+            })),
+        }),
+        references: vec![DUMMY_DIGEST_2.to_vec()],
+        narinfo: None,
+    };
+    assert!(path_info.validate().is_ok());
+
+    // create a PathInfo with a narinfo field, but an inconsistent set of references
+    let path_info_with_narinfo_missing_refs = PathInfo {
+        narinfo: Some(proto::NarInfo {
+            nar_size: 0,
+            nar_sha256: DUMMY_DIGEST.to_vec(),
+            signatures: vec![],
+            reference_names: vec![],
+        }),
+        ..path_info.clone()
+    };
+    match path_info_with_narinfo_missing_refs
+        .validate()
+        .expect_err("must_fail")
+    {
+        ValidatePathInfoError::InconsistentNumberOfReferences(_, _) => {}
+        _ => panic!("unexpected error"),
+    };
+
+    // create a pathinfo with the correct number of references, should suceed
+    let path_info_with_narinfo = PathInfo {
+        narinfo: Some(proto::NarInfo {
+            nar_size: 0,
+            nar_sha256: DUMMY_DIGEST.to_vec(),
+            signatures: vec![],
+            reference_names: vec![format!("/nix/store/{}", DUMMY_NAME)],
+        }),
+        ..path_info.clone()
+    };
+    assert!(path_info_with_narinfo.validate().is_ok());
+}