Add Debug trait for X509 and other types.

This currently leaves out at least two useful things:
 - The detailed SubjectPublicKeyInfo, e.g. the modulus of RSA keys.
 - Extensions.

openssl/src/asn1.rs

@@ -67,12 +67,16 @@ foreign_type_and_impl_send_sync! {
 impl fmt::Display for Asn1GeneralizedTimeRef {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         unsafe {
-            let mem_bio = MemBio::new()?;
-            cvt(ffi::ASN1_GENERALIZEDTIME_print(
+            match MemBio::new() {
+                Err(_) => f.write_str(""),
+                Ok(mem_bio) => match cvt(ffi::ASN1_GENERALIZEDTIME_print(
                     mem_bio.as_ptr(),
                     self.as_ptr(),
-            ))?;
-            write!(f, "{}", str::from_utf8_unchecked(mem_bio.get_buf()))
+                )) {
+                    Err(_) => f.write_str(""),
+                    Ok(_) => f.write_str(str::from_utf8_unchecked(mem_bio.get_buf())),
+                },
+            }
         }
     }
 }
@@ -207,12 +211,22 @@ impl<'a> PartialOrd<Asn1Time> for &'a Asn1TimeRef {
 impl fmt::Display for Asn1TimeRef {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         unsafe {
-            let mem_bio = MemBio::new()?;
-            cvt(ffi::ASN1_TIME_print(mem_bio.as_ptr(), self.as_ptr()))?;
-            write!(f, "{}", str::from_utf8_unchecked(mem_bio.get_buf()))
+            match MemBio::new() {
+                Err(_) => f.write_str("error"),
+                Ok(mem_bio) => match cvt(ffi::ASN1_TIME_print(mem_bio.as_ptr(), self.as_ptr())) {
+                    Err(_) => f.write_str("error"),
+                    Ok(_) => f.write_str(str::from_utf8_unchecked(mem_bio.get_buf())),
+                },
             }
         }
     }
+}
+
+impl fmt::Debug for Asn1TimeRef {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.write_str(&self.to_string())
+    }
+}
 
 impl Asn1Time {
     fn new() -> Result<Asn1Time, ErrorStack> {
@@ -389,6 +403,15 @@ impl Asn1StringRef {
     }
 }
 
+impl fmt::Debug for Asn1StringRef {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        match self.as_utf8() {
+            Ok(openssl_string) => openssl_string.fmt(fmt),
+            Err(_) => fmt.write_str("error"),
+        }
+    }
+}
+
 foreign_type_and_impl_send_sync! {
     type CType = ffi::ASN1_INTEGER;
     fn drop = ffi::ASN1_INTEGER_free;
@@ -527,11 +550,19 @@ impl fmt::Display for Asn1ObjectRef {
                 self.as_ptr(),
                 0,
             );
-            let s = str::from_utf8(&buf[..len as usize]).map_err(|_| fmt::Error)?;
-            fmt.write_str(s)
+            match str::from_utf8(&buf[..len as usize]) {
+                Err(_) => fmt.write_str("error"),
+                Ok(s) => fmt.write_str(s),
             }
         }
     }
+}
+
+impl fmt::Debug for Asn1ObjectRef {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        fmt.write_str(self.to_string().as_str())
+    }
+}
 
 cfg_if! {
     if #[cfg(any(ossl110, libressl273))] {

openssl/src/pkey.rs

@@ -49,6 +49,7 @@ use ffi;
 use foreign_types::{ForeignType, ForeignTypeRef};
 use libc::{c_int, c_long};
 use std::ffi::CString;
+use std::fmt;
 use std::mem;
 use std::ptr;
 
@@ -286,6 +287,27 @@ where
     }
 }
 
+impl<T> fmt::Debug for PKey<T> {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        let alg = match self.id() {
+            Id::RSA => "RSA",
+            Id::HMAC => "HMAC",
+            Id::DSA => "DSA",
+            Id::DH => "DH",
+            Id::EC => "EC",
+            #[cfg(ossl111)]
+            Id::ED25519 => "Ed25519",
+            #[cfg(ossl111)]
+            Id::ED448 => "Ed448",
+            _ => "unknown",
+        };
+        fmt.debug_struct("public_key")
+            .field("algorithm", &alg)
+            .finish()
+        // TODO: Print details for each specific type of key
+    }
+}
+
 impl<T> Clone for PKey<T> {
     fn clone(&self) -> PKey<T> {
         PKeyRef::to_owned(self)

openssl/src/stack.rs

@@ -3,6 +3,7 @@ use foreign_types::{ForeignType, ForeignTypeRef, Opaque};
 use libc::c_int;
 use std::borrow::Borrow;
 use std::convert::AsRef;
+use std::fmt;
 use std::iter;
 use std::marker::PhantomData;
 use std::mem;
@@ -43,6 +44,15 @@ pub struct Stack<T: Stackable>(*mut T::StackType);
 unsafe impl<T: Stackable + Send> Send for Stack<T> {}
 unsafe impl<T: Stackable + Sync> Sync for Stack<T> {}
 
+impl<T> fmt::Debug for Stack<T>
+where
+    T: Stackable,
+    T::Ref: fmt::Debug,
+{
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        fmt.debug_list().entries(self).finish()
+    }
+}
 impl<T: Stackable> Drop for Stack<T> {
     fn drop(&mut self) {
         unsafe {

openssl/src/x509/mod.rs

@@ -671,6 +671,35 @@ impl Clone for X509 {
     }
 }
 
+impl fmt::Debug for X509 {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let serial = match &self.serial_number().to_bn() {
+            Ok(bn) => match bn.to_hex_str() {
+                Ok(hex) => hex.to_string(),
+                Err(_) => "".to_string(),
+            },
+            Err(_) => "".to_string(),
+        };
+        let mut debug_struct = formatter.debug_struct("X509");
+        debug_struct.field("serial_number", &serial);
+        debug_struct.field("signature_algorithm", &self.signature_algorithm().object());
+        debug_struct.field("issuer", &self.issuer_name());
+        debug_struct.field("subject", &self.subject_name());
+        if let Some(subject_alt_names) = &self.subject_alt_names() {
+            debug_struct.field("subject_alt_names", subject_alt_names);
+        }
+        debug_struct.field("not_before", &self.not_before());
+        debug_struct.field("not_after", &self.not_after());
+
+        if let Ok(public_key) = &self.public_key() {
+            debug_struct.field("public_key", public_key);
+        };
+        // TODO: Print extensions once they are supported on the X509 struct.
+
+        debug_struct.finish()
+    }
+}
+
 impl AsRef<X509Ref> for X509Ref {
     fn as_ref(&self) -> &X509Ref {
         self
@@ -867,6 +896,12 @@ impl X509NameRef {
     }
 }
 
+impl fmt::Debug for X509NameRef {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.debug_list().entries(self.entries()).finish()
+    }
+}
+
 /// A type to destructure and examine an `X509Name`.
 pub struct X509NameEntries<'a> {
     name: &'a X509NameRef,
@@ -942,6 +977,12 @@ impl X509NameEntryRef {
     }
 }
 
+impl fmt::Debug for X509NameEntryRef {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_fmt(format_args!("{:?} = {:?}", self.object(), self.data()))
+    }
+}
+
 /// A builder used to construct an `X509Req`.
 pub struct X509ReqBuilder(X509Req);
 
@@ -1298,6 +1339,25 @@ impl GeneralNameRef {
     }
 }
 
+impl fmt::Debug for GeneralNameRef {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        if let Some(email) = self.email() {
+            return formatter.write_str(email);
+        }
+        if let Some(dnsname) = self.dnsname() {
+            return formatter.write_str(dnsname);
+        }
+        if let Some(uri) = self.uri() {
+            return formatter.write_str(uri);
+        }
+        if let Some(ipaddress) = self.ipaddress() {
+            let result = String::from_utf8_lossy(ipaddress);
+            return formatter.write_str(&result);
+        }
+        Ok(())
+    }
+}
+
 impl Stackable for GeneralName {
     type StackType = ffi::stack_st_GENERAL_NAME;
 }

openssl/src/x509/tests.rs

@@ -31,6 +31,34 @@ fn test_cert_loading() {
     assert_eq!(hash_vec, &*fingerprint);
 }
 
+#[test]
+fn test_debug() {
+    let cert = include_bytes!("../../test/cert.pem");
+    let cert = X509::from_pem(cert).unwrap();
+    let debugged = format!("{:#?}", cert);
+    let expected = r#"X509 {
+    serial_number: "8771F7BDEE982FA5",
+    signature_algorithm: sha256WithRSAEncryption,
+    issuer: [
+        countryName = "AU",
+        stateOrProvinceName = "Some-State",
+        organizationName = "Internet Widgits Pty Ltd",
+    ],
+    subject: [
+        countryName = "AU",
+        stateOrProvinceName = "Some-State",
+        organizationName = "Internet Widgits Pty Ltd",
+        commonName = "foobar.com",
+    ],
+    not_before: Aug 14 17:00:03 2016 GMT,
+    not_after: Aug 12 17:00:03 2026 GMT,
+    public_key: public_key {
+        algorithm: "RSA",
+    },
+}"#;
+    assert_eq!(expected, debugged);
+}
+
 #[test]
 fn test_cert_issue_validity() {
     let cert = include_bytes!("../../test/cert.pem");