Adds `RsaPssSaltlen` enum to encode the special values

openssl/src/sign.rs

@@ -79,6 +79,29 @@ use ffi::{EVP_MD_CTX_free, EVP_MD_CTX_new};
 #[cfg(any(ossl101, ossl102))]
 use ffi::{EVP_MD_CTX_create as EVP_MD_CTX_new, EVP_MD_CTX_destroy as EVP_MD_CTX_free};
 
+/// Salt lengths that must be used with `set_rsa_pss_saltlen`.
+pub enum RsaPssSaltlen {
+    /// The salt length is set to the digest length.
+    /// Corresponds to the special value `-1`.
+    DigestLength,
+    /// The salt length is set to the maximum permissible value.
+    /// Corresponds to the special value `-2`.
+    MaximumLength,
+    /// Sets the salt length to the given value.
+    Custom(u32)
+}
+
+impl RsaPssSaltlen {
+    /// Returns the integer representation of `Oid`.
+    fn as_raw(&self) -> c_int {
+        match *self {
+            RsaPssSaltlen::DigestLength => -1,
+            RsaPssSaltlen::MaximumLength => -2,
+            RsaPssSaltlen::Custom(val) => val as c_int,
+        }
+    }
+}
+
 /// A type which computes cryptographic signatures of data.
 pub struct Signer<'a> {
     md_ctx: *mut ffi::EVP_MD_CTX,
@@ -168,11 +191,11 @@ impl<'a> Signer<'a> {
     /// This corresponds to [`EVP_PKEY_CTX_set_rsa_pss_saltlen`].
     ///
     /// [`EVP_PKEY_CTX_set_rsa_pss_saltlen`]: https://www.openssl.org/docs/man1.1.0/crypto/EVP_PKEY_CTX_set_rsa_pss_saltlen.html
-    pub fn set_rsa_pss_saltlen(&mut self, len: c_int) -> Result<(), ErrorStack> {
+    pub fn set_rsa_pss_saltlen(&mut self, len: RsaPssSaltlen) -> Result<(), ErrorStack> {
         unsafe {
             cvt(ffi::EVP_PKEY_CTX_set_rsa_pss_saltlen(
                 self.pctx,
-                len,
+                len.as_raw(),
             )).map(|_| ())
         }
     }
@@ -360,11 +383,11 @@ impl<'a> Verifier<'a> {
     /// This corresponds to [`EVP_PKEY_CTX_set_rsa_pss_saltlen`].
     ///
     /// [`EVP_PKEY_CTX_set_rsa_pss_saltlen`]: https://www.openssl.org/docs/man1.1.0/crypto/EVP_PKEY_CTX_set_rsa_pss_saltlen.html
-    pub fn set_rsa_pss_saltlen(&mut self, len: c_int) -> Result<(), ErrorStack> {
+    pub fn set_rsa_pss_saltlen(&mut self, len: RsaPssSaltlen) -> Result<(), ErrorStack> {
         unsafe {
             cvt(ffi::EVP_PKEY_CTX_set_rsa_pss_saltlen(
                 self.pctx,
-                len,
+                len.as_raw(),
             )).map(|_| ())
         }
     }
@@ -451,7 +474,7 @@ mod test {
     use std::iter;
 
     use hash::MessageDigest;
-    use sign::{Signer, Verifier};
+    use sign::{Signer, Verifier, RsaPssSaltlen};
     use ec::{EcGroup, EcKey};
     use nid::Nid;
     use rsa::{Padding, Rsa};
@@ -634,14 +657,14 @@ mod test {
         let mut signer = Signer::new(MessageDigest::sha256(), &pkey).unwrap();
         signer.set_rsa_padding(Padding::PKCS1_PSS).unwrap();
         assert_eq!(signer.rsa_padding().unwrap(), Padding::PKCS1_PSS);
-        signer.set_rsa_pss_saltlen(-1).unwrap();
+        signer.set_rsa_pss_saltlen(RsaPssSaltlen::DigestLength).unwrap();
         signer.set_rsa_mgf1_md(MessageDigest::sha256()).unwrap();
         signer.update(&Vec::from_hex(INPUT).unwrap()).unwrap();
         let signature = signer.sign_to_vec().unwrap();
 
         let mut verifier = Verifier::new(MessageDigest::sha256(), &pkey).unwrap();
         verifier.set_rsa_padding(Padding::PKCS1_PSS).unwrap();
-        verifier.set_rsa_pss_saltlen(-1).unwrap();
+        verifier.set_rsa_pss_saltlen(RsaPssSaltlen::DigestLength).unwrap();
         verifier.set_rsa_mgf1_md(MessageDigest::sha256()).unwrap();
         verifier.update(&Vec::from_hex(INPUT).unwrap()).unwrap();
         assert!(verifier.verify(&signature).unwrap());