Add new fingerprinter

Cargo.toml

@@ -42,6 +42,7 @@ strum = { version = "0.26.2", features = ["derive"] }
 alphanumeric-sort = "1.5.3"
 tap = "1.0.1"
 tracing = "0.1.40"
+sha1 = "0.10.6"
 
 [dev-dependencies]
 pretty_assertions = "1.4.0"

src/fingerprint/jar.rs

@@ -1,5 +1,6 @@
 use std::io::{BufRead, Seek};
 
+use sha1::Sha1;
 use sha2::{Digest, Sha256};
 use tap::Pipe;
 use tracing::warn;
@@ -22,6 +23,15 @@ pub fn raw(stream: impl BufRead + Seek) -> Result<Option<Fingerprint>, Error> {
     }
 }
 
+/// Fingerprint the java archive the same way as Maven Central.
+#[tracing::instrument(level = tracing::Level::DEBUG, skip_all, ret)]
+pub fn maven_central(mut stream: impl BufRead + Seek) -> Result<Option<Fingerprint>, Error> {
+    let mut hasher = Sha1::new();
+    std::io::copy(&mut stream, &mut hasher)?;
+    let content = Content::from_digest(hasher);
+    Ok(Some(Fingerprint::new(Kind::JarMavenCentralV1, content)))
+}
+
 /// Fingerprint class files inside a java archive (a JAR).
 #[tracing::instrument(level = tracing::Level::DEBUG, skip_all, ret)]
 pub fn class(stream: impl BufRead + Seek) -> Result<Option<Fingerprint>, Error> {

src/lib.rs

@@ -123,6 +123,15 @@ pub enum Kind {
     #[strum(serialize = "v1.raw.jar")]
     JarRawV1,
 
+    /// Represents a fingerprint derived by hashing the raw contents of a JAR file in the same manner
+    /// as Maven Central. The idea is that such fingerprints can then be looked up via the
+    /// Maven Central REST API as a fallback to our own indexing.
+    ///
+    /// Specifically:
+    /// - The content of the JAR file is hashed as-is using the sha1 algorithm.
+    #[strum(serialize = "v1.mavencentral.jar")]
+    JarMavenCentralV1,
+
     /// Represents a fingerprint derived by hashing the raw contents of a JAR file with the SHA256 algorithm
     /// in a platform-independent manner.
     ///
@@ -323,6 +332,7 @@ impl Fingerprint {
             Kind::CommentStrippedSha256 => fingerprint::text::comment_stripped(stream),
             Kind::JarRawV1 => fingerprint::jar::raw(stream),
             Kind::JarClassV1 => fingerprint::jar::class(stream),
+            Kind::JarMavenCentralV1 => fingerprint::jar::maven_central(stream),
         }
     }