Add Display implementation to X509NameRef

Internally, call `X509_NAME_print_ex(3)` with RFC2253 flags and disable
UTF-8 escaping so the result is a UTF-8-encoded string.

Signed-off-by: Ross Williams <ross@ross-williams.net>

openssl-sys/src/handwritten/x509.rs

@@ -489,6 +489,12 @@ const_ptr_api! {
         pub fn X509_NAME_entry_count(n: #[const_ptr_if(any(ossl110, libressl280))] X509_NAME) -> c_int;
         pub fn X509_NAME_get_index_by_NID(n: #[const_ptr_if(any(ossl300, libressl280))] X509_NAME, nid: c_int, last_pos: c_int) -> c_int;
         pub fn X509_NAME_get_entry(n: #[const_ptr_if(any(ossl110, libressl280))] X509_NAME, loc: c_int) -> *mut X509_NAME_ENTRY;
+        pub fn X509_NAME_print_ex(
+            out: *mut BIO,
+            n: #[const_ptr_if(any(ossl110, libressl280))] X509_NAME,
+            indent: c_int,
+            flags: c_ulong,
+        ) -> c_int;
         pub fn X509_NAME_add_entry_by_NID(
             x: *mut X509_NAME,
             field: c_int,

openssl-sys/src/x509.rs

@@ -4,8 +4,31 @@ pub const X509_FILETYPE_PEM: c_int = 1;
 pub const X509_FILETYPE_ASN1: c_int = 2;
 pub const X509_FILETYPE_DEFAULT: c_int = 3;
 
+pub const XN_FLAG_SEP_COMMA_PLUS: c_ulong = 1 << 16;
+pub const XN_FLAG_DN_REV: c_ulong = 1 << 20;
+pub const XN_FLAG_FN_SN: c_ulong = 0;
+pub const XN_FLAG_DUMP_UNKNOWN_FIELDS: c_ulong = 1 << 24;
+pub const XN_FLAG_RFC2253: c_ulong = ASN1_STRFLGS_RFC2253
+    | XN_FLAG_SEP_COMMA_PLUS
+    | XN_FLAG_DN_REV
+    | XN_FLAG_FN_SN
+    | XN_FLAG_DUMP_UNKNOWN_FIELDS;
+
 pub const ASN1_R_HEADER_TOO_LONG: c_int = 123;
 
+pub const ASN1_STRFLGS_ESC_2253: c_ulong = 1;
+pub const ASN1_STRFLGS_ESC_CTRL: c_ulong = 2;
+pub const ASN1_STRFLGS_ESC_MSB: c_ulong = 4;
+pub const ASN1_STRFLGS_UTF8_CONVERT: c_ulong = 0x10;
+pub const ASN1_STRFLGS_DUMP_UNKNOWN: c_ulong = 0x100;
+pub const ASN1_STRFLGS_DUMP_DER: c_ulong = 0x200;
+pub const ASN1_STRFLGS_RFC2253: c_ulong = ASN1_STRFLGS_ESC_2253
+    | ASN1_STRFLGS_ESC_CTRL
+    | ASN1_STRFLGS_ESC_MSB
+    | ASN1_STRFLGS_UTF8_CONVERT
+    | ASN1_STRFLGS_DUMP_UNKNOWN
+    | ASN1_STRFLGS_DUMP_DER;
+
 cfg_if! {
     if #[cfg(not(any(ossl110, libressl350)))] {
         pub const X509_LU_FAIL: c_int = 0;

openssl/src/x509/mod.rs

@@ -9,7 +9,7 @@
 
 use cfg_if::cfg_if;
 use foreign_types::{ForeignType, ForeignTypeRef, Opaque};
-use libc::{c_int, c_long, c_uint, c_void};
+use libc::{c_int, c_long, c_uint, c_ulong, c_void};
 use std::cmp::{self, Ordering};
 use std::convert::{TryFrom, TryInto};
 use std::error::Error;
@@ -1288,6 +1288,26 @@ impl fmt::Debug for X509NameRef {
     }
 }
 
+impl fmt::Display for X509NameRef {
+    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
+        const INDENT: i32 = 0;
+        const FLAGS: c_ulong = ffi::XN_FLAG_RFC2253 & !ffi::ASN1_STRFLGS_ESC_MSB;
+
+        unsafe {
+            let bio = crate::bio::MemBio::new()?;
+            cvt_n(ffi::X509_NAME_print_ex(
+                bio.as_ptr(),
+                self.as_ptr(),
+                INDENT,
+                FLAGS,
+            ))
+            .or(Err(fmt::Error))?;
+            let value = core::str::from_utf8_unchecked(bio.get_buf());
+            formatter.write_str(value)
+        }
+    }
+}
+
 /// A type to destructure and examine an `X509Name`.
 pub struct X509NameEntries<'a> {
     name: &'a X509NameRef,

openssl/src/x509/tests.rs

@@ -1192,3 +1192,30 @@ fn test_store_all_certificates() {
 
     assert_eq!(store.all_certificates().len(), 1);
 }
+
+#[test]
+fn test_name_display() {
+    let cert = include_bytes!("../../test/cert.pem");
+    let cert = X509::from_pem(cert).unwrap();
+
+    const EXPECTED_TO_STRING_OUTPUT: &str =
+        "CN=foobar.com,O=Internet Widgits Pty Ltd,ST=Some-State,C=AU";
+
+    let rdn = cert.subject_name().to_string();
+    assert_eq!(
+        rdn, EXPECTED_TO_STRING_OUTPUT,
+        "output did not match expected",
+    );
+
+    let emoji_cert = include_bytes!("../../test/emoji_cert.pem");
+    let emoji_cert = X509::from_pem(emoji_cert).unwrap();
+
+    const EXPECTED_EMOJI_OUTPUT: &str =
+        "CN=www.example.com,O=\u{1f980}\u{1f9ea}\u{1f44d},ST=YY,C=XX";
+
+    let rdn = emoji_cert.subject_name().to_string();
+    assert_eq!(
+        rdn, EXPECTED_EMOJI_OUTPUT,
+        "formatting of cert name with Unicode Emoji failed"
+    );
+}

openssl/test/emoji_cert.pem

@@ -0,0 +1,22 @@
+-----BEGIN CERTIFICATE-----
+MIIDqDCCApCgAwIBAgIUWZnfBdTaxSrLilsn6tHRTyZU6PgwDQYJKoZIhvcNAQEL
+BQAwSzELMAkGA1UEBhMCWFgxCzAJBgNVBAgMAllZMR0wGwYDVQQKDBRTb21lIENB
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+h5GaHDAJezJnPMx4kxrM12r5yWw9lkf5J/TGA9zAzud+/0A8+K3AQLMSYljLynvY
+EkK4cLHrQ6LRhwLq4jtj6qATwN1k0iQmwhMPrfOo9s+9CxvZNuf7a/OdWGU0qrt3
+YNHMJsioM4Jvt+RvU8ccjXMviZbDe/2pIPv4eU309q1cSYf7pomK2vduk6vuTeAz
+V1hhUFbr+gU00TVnzGIwpEMkoQEPlvYEXz7uVw==
+-----END CERTIFICATE-----