Commit 966cb2ed authored by Rob Shearman's avatar Rob Shearman
Browse files

Add BigNumRef::to_vec_padded 

Wire protocols sometimes define a fixed size for fields that may be
derived from a BigNum, so it is useful to be able to obtain a Vec<u8>
that has been padded accordingly.

So add a BN_bn2binpad -sys function and a to_vec_padded wrapper around
this for BigNumRef.
parent bf20ebeb

openssl-sys/src/bn.rs

+2 −0
Original line number Diff line number Diff line
@@ -19,6 +19,8 @@ extern "C" { 
    pub fn BN_clear_free(bn: *mut BIGNUM);

    pub fn BN_bin2bn(s: *const u8, size: c_int, ret: *mut BIGNUM) -> *mut BIGNUM;

    pub fn BN_bn2bin(a: *const BIGNUM, to: *mut u8) -> c_int;

    #[cfg(ossl110)]

    pub fn BN_bn2binpad(a: *const BIGNUM, to: *mut u8, tolen: c_int) -> c_int;

    pub fn BN_sub(r: *mut BIGNUM, a: *const BIGNUM, b: *const BIGNUM) -> c_int;

    pub fn BN_add(r: *mut BIGNUM, a: *const BIGNUM, b: *const BIGNUM) -> c_int;

    pub fn BN_mul(r: *mut BIGNUM, a: *const BIGNUM, b: *const BIGNUM, ctx: *mut BN_CTX) -> c_int;

openssl/src/bn.rs

+31 −0
Original line number Diff line number Diff line
@@ -885,6 +885,37 @@ impl BigNumRef { 
        v

    }



    /// Returns a big-endian byte vector representation of the absolute value of `self` padded

    /// to `pad_to` bytes.

    ///

    /// If `pad_to` is less than `self.num_bytes()` then an error is returned.

    ///

    /// `self` can be recreated by using `from_slice`.

    ///

    /// ```

    /// # use openssl::bn::BigNum;

    /// let bn = BigNum::from_u32(0x4543).unwrap();

    ///

    /// let bn_vec = bn.to_vec_padded(4).unwrap();

    /// assert_eq!(&bn_vec, &[0, 0, 0x45, 0x43]);

    ///

    /// let r = bn.to_vec_padded(1);

    /// assert!(r.is_err());

    ///

    /// let bn = -BigNum::from_u32(0x4543).unwrap();

    /// let bn_vec = bn.to_vec_padded(4).unwrap();

    /// assert_eq!(&bn_vec, &[0, 0, 0x45, 0x43]);

    /// ```

    #[cfg(ossl110)]

    pub fn to_vec_padded(&self, pad_to: i32) -> Result<Vec<u8>, ErrorStack> {

        let mut v = Vec::with_capacity(pad_to as usize);

        unsafe {

            cvt(ffi::BN_bn2binpad(self.as_ptr(), v.as_mut_ptr(), pad_to))?;

            v.set_len(pad_to as usize);

        }

        Ok(v)

    }



    /// Returns a decimal string representation of `self`.

    ///

    /// ```