1 files changed, 73 insertions, 0 deletions

diff --git a/packet-detector/src/tls_util.rs b/packet-detector/src/tls_util.rs
new file mode 100644
index 0000000..456991b
--- /dev/null
+++ b/packet-detector/src/tls_util.rs
@@ -0,0 +1,73 @@
+use rcgen::{DistinguishedName, DnType};
+use rustls::client::danger::{HandshakeSignatureValid, ServerCertVerified, ServerCertVerifier};
+use rustls::pki_types::{CertificateDer, ServerName, UnixTime};
+use rustls::{DigitallySignedStruct, Error, SignatureScheme};
+use sha2::{Digest, Sha256};
+use x509_parser::prelude::*;
+
+/// SHA256 fingerprint (truncated to 16 bytes by default)
+pub fn fingerprint(cert: &CertificateDer<'_>, full: bool) -> String {
+    let hash = Sha256::digest(cert.as_ref());
+    if full { hex::encode(hash) } else { hex::encode(&hash[..16]) }
+}
+
+pub fn dn(cn: &str, org: &str) -> DistinguishedName {
+    let mut d = DistinguishedName::new();
+    d.push(DnType::CommonName, cn);
+    d.push(DnType::OrganizationName, org);
+    d.push(DnType::CountryName, "US");
+    d
+}
+
+/// Parse certs from PEM
+pub fn parse_pem(pem: &str) -> Result<Vec<CertificateDer<'static>>, std::io::Error> {
+    rustls_pemfile::certs(&mut pem.as_bytes()).collect()
+}
+
+fn schemes() -> Vec<SignatureScheme> {
+    rustls::crypto::ring::default_provider()
+        .signature_verification_algorithms
+        .supported_schemes()
+}
+
+/// Macro to implement the boilerplate verifier methods
+macro_rules! impl_verifier_base {
+    () => {
+        fn verify_tls12_signature(&self, _: &[u8], _: &CertificateDer<'_>, _: &DigitallySignedStruct) -> Result<HandshakeSignatureValid, Error> {
+            Ok(HandshakeSignatureValid::assertion())
+        }
+        fn verify_tls13_signature(&self, _: &[u8], _: &CertificateDer<'_>, _: &DigitallySignedStruct) -> Result<HandshakeSignatureValid, Error> {
+            Ok(HandshakeSignatureValid::assertion())
+        }
+        fn supported_verify_schemes(&self) -> Vec<SignatureScheme> {
+            schemes()
+        }
+    };
+}
+
+/// Accepts all certificates, logs info
+#[derive(Debug)]
+pub struct LoggingVerifier;
+
+impl ServerCertVerifier for LoggingVerifier {
+    fn verify_server_cert(&self, cert: &CertificateDer<'_>, intermediates: &[CertificateDer<'_>], _: &ServerName<'_>, _: &[u8], _: UnixTime) -> Result<ServerCertVerified, Error> {
+        println!("\n=== Server Certificate ===");
+        match X509Certificate::from_der(cert.as_ref()) {
+            Ok((_, x)) => {
+                println!("Subject: {}", x.subject());
+                println!("Issuer:  {}", x.issuer());
+                println!("SHA256:  {}", fingerprint(cert, true));
+                if x.subject() == x.issuer() { println!("Type:    Self-Signed"); }
+            }
+            Err(e) => println!("Parse failed: {}", e),
+        }
+        for (i, c) in intermediates.iter().enumerate() {
+            if let Ok((_, x)) = X509Certificate::from_der(c.as_ref()) {
+                println!("Intermediate #{}: {}", i + 1, x.subject());
+            }
+        }
+        println!("Chain length: {}\n", 1 + intermediates.len());
+        Ok(ServerCertVerified::assertion())
+    }
+    impl_verifier_base!();
+}