sbom_tools/diff/changes/

vulnerabilities.rs

//! Vulnerability change computer implementation.

use crate::diff::traits::{ChangeComputer, ComponentMatches, VulnerabilityChangeSet};
use crate::diff::VulnerabilityDetail;
use crate::model::{CanonicalId, NormalizedSbom};
use std::collections::{HashMap, HashSet, VecDeque};

/// Computes vulnerability-level changes between SBOMs.
pub struct VulnerabilityChangeComputer;

impl VulnerabilityChangeComputer {
    /// Create a new vulnerability change computer.
    #[must_use] 
    pub const fn new() -> Self {
        Self
    }
}

impl Default for VulnerabilityChangeComputer {
    fn default() -> Self {
        Self::new()
    }
}

/// Compute component depths from SBOM dependency edges using BFS.
/// Returns a map of component ID -> depth (1 = direct, 2+ = transitive).
fn compute_depths(sbom: &NormalizedSbom) -> HashMap<CanonicalId, u32> {
    let mut depths = HashMap::with_capacity(sbom.components.len());

    // Build forward edge map: parent -> [children]
    let mut edges: HashMap<&CanonicalId, Vec<&CanonicalId>> =
        HashMap::with_capacity(sbom.components.len());
    let mut has_parents: HashSet<&CanonicalId> = HashSet::with_capacity(sbom.components.len());

    for edge in &sbom.edges {
        edges.entry(&edge.from).or_default().push(&edge.to);
        has_parents.insert(&edge.to);
    }

    // Find roots (components with no incoming edges)
    let roots: Vec<&CanonicalId> = sbom
        .components
        .keys()
        .filter(|id| !has_parents.contains(id))
        .collect();

    // BFS from roots to compute minimum depths
    let mut queue: VecDeque<(&CanonicalId, u32)> = VecDeque::new();

    // Roots are at depth 0 (the "product" level)
    for root in &roots {
        queue.push_back((*root, 0));
    }

    while let Some((id, depth)) = queue.pop_front() {
        // Skip if we've already found a shorter path
        if let Some(&existing) = depths.get(id)
            && depth >= existing {
                continue;
            }
        depths.insert(id.clone(), depth);

        // Process children at depth + 1
        if let Some(children) = edges.get(id) {
            for child in children {
                let child_depth = depth + 1;
                // Only queue if we haven't seen a shorter path
                if depths.get(*child).is_none_or(|&d| d > child_depth) {
                    queue.push_back((*child, child_depth));
                }
            }
        }
    }

    depths
}

impl ChangeComputer for VulnerabilityChangeComputer {
    type ChangeSet = VulnerabilityChangeSet;

    fn compute(
        &self,
        old: &NormalizedSbom,
        new: &NormalizedSbom,
        _matches: &ComponentMatches,
    ) -> VulnerabilityChangeSet {
        let mut result = VulnerabilityChangeSet::new();

        // Compute component depths for both SBOMs
        let old_depths = compute_depths(old);
        let new_depths = compute_depths(new);

        // Estimate vulnerability counts for pre-allocation
        let old_vuln_count: usize = old.components.values().map(|c| c.vulnerabilities.len()).sum();
        let new_vuln_count: usize = new.components.values().map(|c| c.vulnerabilities.len()).sum();

        // Collect old vulnerabilities with depth info
        let mut old_vulns: HashMap<String, VulnerabilityDetail> =
            HashMap::with_capacity(old_vuln_count);
        for (id, comp) in &old.components {
            let depth = old_depths.get(id).copied();
            for vuln in &comp.vulnerabilities {
                let key = format!("{}:{}", vuln.id, id);
                old_vulns.insert(key, VulnerabilityDetail::from_ref_with_depth(vuln, comp, depth));
            }
        }

        // Collect new vulnerabilities with depth info
        let mut new_vulns: HashMap<String, VulnerabilityDetail> =
            HashMap::with_capacity(new_vuln_count);
        for (id, comp) in &new.components {
            let depth = new_depths.get(id).copied();
            for vuln in &comp.vulnerabilities {
                let key = format!("{}:{}", vuln.id, id);
                new_vulns.insert(key, VulnerabilityDetail::from_ref_with_depth(vuln, comp, depth));
            }
        }

        // Find introduced vulnerabilities (in new but not old)
        for detail in new_vulns.values() {
            // Check by vuln ID only (component might have been renamed/matched)
            let vuln_id = &detail.id;
            let exists_in_old = old_vulns.values().any(|v| &v.id == vuln_id);
            if !exists_in_old {
                result.introduced.push(detail.clone());
            }
        }

        // Find resolved vulnerabilities (in old but not new)
        for detail in old_vulns.values() {
            let vuln_id = &detail.id;
            let exists_in_new = new_vulns.values().any(|v| &v.id == vuln_id);
            if !exists_in_new {
                result.resolved.push(detail.clone());
            }
        }

        // Find persistent vulnerabilities (in both)
        for detail in new_vulns.values() {
            let vuln_id = &detail.id;
            let exists_in_old = old_vulns.values().any(|v| &v.id == vuln_id);
            if exists_in_old {
                result.persistent.push(detail.clone());
            }
        }

        // Sort by severity
        result.sort_by_severity();

        result
    }

    fn name(&self) -> &'static str {
        "VulnerabilityChangeComputer"
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_vulnerability_change_computer_default() {
        let computer = VulnerabilityChangeComputer;
        assert_eq!(computer.name(), "VulnerabilityChangeComputer");
    }

    #[test]
    fn test_empty_sboms() {
        let computer = VulnerabilityChangeComputer;
        let old = NormalizedSbom::default();
        let new = NormalizedSbom::default();
        let matches = ComponentMatches::new();

        let result = computer.compute(&old, &new, &matches);
        assert!(result.is_empty());
    }
}