single `ffi` module

1 files changed, 56 insertions, 135 deletions

diff --git a/src/bn/mod.rs b/src/bn/mod.rs
index cc64d8cd..29ffd413 100644
--- a/src/bn/mod.rs
+++ b/src/bn/mod.rs
@@ -1,88 +1,12 @@
-
-use libc::{c_void, c_int, c_ulong, c_char};
+use libc::{c_int, c_ulong};
 use std::{fmt, ptr};
 use std::c_str::CString;
 use std::num::{One, Zero};
 
+use ffi;
 use ssl::error::SslError;
 
-#[allow(dead_code)]
-#[repr(C)]
-struct BIGNUM {
-    d: *mut c_void,
-    top: c_int,
-    dmax: c_int,
-    neg: c_int,
-    flags: c_int,
-}
-
-#[allow(non_camel_case_types)]
-type BN_CTX = *mut c_void;
-
-#[link(name = "crypto")]
-extern {
-    fn BN_new() -> *mut BIGNUM;
-    fn BN_clear_free(bn: *mut BIGNUM);
-
-    fn BN_CTX_new() -> *mut BN_CTX;
-    fn BN_CTX_free(ctx: *mut BN_CTX);
-
-    fn BN_set_word(bn: *mut BIGNUM, n: c_ulong) -> c_int;
-    fn BN_set_negative(bn: *mut BIGNUM, n: c_int);
-    fn BN_num_bits(bn: *mut BIGNUM) -> c_int;
-
-    /* Arithmetic operations on BIGNUMs */
-    fn BN_add(r: *mut BIGNUM, a: *mut BIGNUM, b: *mut BIGNUM) -> c_int;
-    fn BN_sub(r: *mut BIGNUM, a: *mut BIGNUM, b: *mut BIGNUM) -> c_int;
-    fn BN_mul(r: *mut BIGNUM, a: *mut BIGNUM, b: *mut BIGNUM, ctx: *mut BN_CTX) -> c_int;
-    fn BN_sqr(r: *mut BIGNUM, a: *mut BIGNUM, ctx: *mut BN_CTX) -> c_int;
-    fn BN_div(dv: *mut BIGNUM, rem: *mut BIGNUM, a: *mut BIGNUM, b: *mut BIGNUM, ctx: *mut BN_CTX) -> c_int;
-    fn BN_nnmod(rem: *mut BIGNUM, a: *mut BIGNUM, m: *mut BIGNUM, ctx: *mut BN_CTX) -> c_int;
-    fn BN_mod_add(r: *mut BIGNUM, a: *mut BIGNUM, b: *mut BIGNUM, m: *mut BIGNUM, ctx: *mut BN_CTX) -> c_int;
-    fn BN_mod_sub(r: *mut BIGNUM, a: *mut BIGNUM, b: *mut BIGNUM, m: *mut BIGNUM, ctx: *mut BN_CTX) -> c_int;
-    fn BN_mod_mul(r: *mut BIGNUM, a: *mut BIGNUM, b: *mut BIGNUM, m: *mut BIGNUM, ctx: *mut BN_CTX) -> c_int;
-    fn BN_mod_sqr(r: *mut BIGNUM, a: *mut BIGNUM, m: *mut BIGNUM, ctx: *mut BN_CTX) -> c_int;
-    fn BN_exp(r: *mut BIGNUM, a: *mut BIGNUM, p: *mut BIGNUM, ctx: *mut BN_CTX) -> c_int;
-    fn BN_mod_exp(r: *mut BIGNUM, a: *mut BIGNUM, p: *mut BIGNUM, m: *mut BIGNUM, ctx: *mut BN_CTX) -> c_int;
-    fn BN_mod_inverse(r: *mut BIGNUM, a: *mut BIGNUM, n: *mut BIGNUM, ctx: *mut BN_CTX) -> *const BIGNUM;
-    fn BN_gcd(r: *mut BIGNUM, a: *mut BIGNUM, b: *mut BIGNUM, ctx: *mut BN_CTX) -> c_int;
-
-    /* Bit operations on BIGNUMs */
-    fn BN_set_bit(a: *mut BIGNUM, n: c_int) -> c_int;
-    fn BN_clear_bit(a: *mut BIGNUM, n: c_int) -> c_int;
-    fn BN_is_bit_set(a: *mut BIGNUM, n: c_int) -> c_int;
-    fn BN_mask_bits(a: *mut BIGNUM, n: c_int) -> c_int;
-    fn BN_lshift(r: *mut BIGNUM, a: *mut BIGNUM, n: c_int) -> c_int;
-    fn BN_lshift1(r: *mut BIGNUM, a: *mut BIGNUM) -> c_int;
-    fn BN_rshift(r: *mut BIGNUM, a: *mut BIGNUM, n: c_int) -> c_int;
-    fn BN_rshift1(r: *mut BIGNUM, a: *mut BIGNUM) -> c_int;
-
-    /* Comparisons on BIGNUMs */
-    fn BN_cmp(a: *mut BIGNUM, b: *mut BIGNUM) -> c_int;
-    fn BN_ucmp(a: *mut BIGNUM, b: *mut BIGNUM) -> c_int;
-    fn BN_is_zero(a: *mut BIGNUM) -> c_int;
-
-    /* Prime handling */
-    fn BN_generate_prime_ex(r: *mut BIGNUM, bits: c_int, safe: c_int, add: *mut BIGNUM, rem: *mut BIGNUM, cb: *const c_void) -> c_int;
-    fn BN_is_prime_ex(p: *mut BIGNUM, checks: c_int, ctx: *mut BN_CTX, cb: *const c_void) -> c_int;
-    fn BN_is_prime_fasttest_ex(p: *mut BIGNUM, checks: c_int, ctx: *mut BN_CTX, do_trial_division: c_int, cb: *const c_void) -> c_int;
-
-    /* Random number handling */
-    fn BN_rand(r: *mut BIGNUM, bits: c_int, top: c_int, bottom: c_int) -> c_int;
-    fn BN_pseudo_rand(r: *mut BIGNUM, bits: c_int, top: c_int, bottom: c_int) -> c_int;
-    fn BN_rand_range(r: *mut BIGNUM, range: *mut BIGNUM) -> c_int;
-    fn BN_pseudo_rand_range(r: *mut BIGNUM, range: *mut BIGNUM) -> c_int;
-
-    /* Conversion from/to binary representation */
-    fn BN_bn2bin(a: *mut BIGNUM, to: *mut u8) -> c_int;
-    fn BN_bin2bn(s: *const u8, size: c_int, ret: *mut BIGNUM) -> *mut BIGNUM;
-
-    /* Conversion from/to string representation */
-    fn BN_bn2dec(a: *mut BIGNUM) -> *const c_char;
-    fn CRYPTO_free(buf: *const c_char);
-}
-
-pub struct BigNum(*mut BIGNUM);
+pub struct BigNum(*mut ffi::BIGNUM);
 
 #[repr(C)]
 pub enum RNGProperty {
@@ -93,12 +17,12 @@ pub enum RNGProperty {
 
 macro_rules! with_ctx(
     ($name:ident, $action:block) => ({
-        let $name = BN_CTX_new();
+        let $name = ffi::BN_CTX_new();
         if ($name).is_null() {
             Err(SslError::get())
         } else {
             let r = $action;
-            BN_CTX_free($name);
+            ffi::BN_CTX_free($name);
             r
         }
     });
@@ -125,7 +49,7 @@ macro_rules! with_bn_in_ctx(
         let tmp = BigNum::new();
         match tmp {
             Ok($name) => {
-                let $ctx_name = BN_CTX_new();
+                let $ctx_name = ffi::BN_CTX_new();
                 if ($ctx_name).is_null() {
                     Err(SslError::get())
                 } else {
@@ -135,7 +59,7 @@ macro_rules! with_bn_in_ctx(
                         } else {
                             Err(SslError::get())
                         };
-                    BN_CTX_free($ctx_name);
+                    ffi::BN_CTX_free($ctx_name);
                     r
                 }
             },
@@ -147,7 +71,7 @@ macro_rules! with_bn_in_ctx(
 impl BigNum {
     pub fn new() -> Result<BigNum, SslError> {
         unsafe {
-            let v = BN_new();
+            let v = ffi::BN_new();
             if v.is_null() {
                 Err(SslError::get())
             } else {
@@ -158,8 +82,8 @@ impl BigNum {
 
     pub fn new_from(n: u64) -> Result<BigNum, SslError> {
         unsafe {
-            let bn = BN_new();
-            if bn.is_null() || BN_set_word(bn, n as c_ulong) == 0 {
+            let bn = ffi::BN_new();
+            if bn.is_null() || ffi::BN_set_word(bn, n as c_ulong) == 0 {
                 Err(SslError::get())
             } else {
                 Ok(BigNum(bn))
@@ -169,8 +93,8 @@ impl BigNum {
 
     pub fn new_from_slice(n: &[u8]) -> Result<BigNum, SslError> {
         unsafe {
-            let bn = BN_new();
-            if bn.is_null() || BN_bin2bn(n.as_ptr(), n.len() as c_int, bn).is_null() {
+            let bn = ffi::BN_new();
+            if bn.is_null() || ffi::BN_bin2bn(n.as_ptr(), n.len() as c_int, bn).is_null() {
                 Err(SslError::get())
             } else {
                 Ok(BigNum(bn))
@@ -180,61 +104,61 @@ impl BigNum {
 
     pub fn checked_sqr(&self) -> Result<BigNum, SslError> {
         unsafe {
-            with_bn_in_ctx!(r, ctx, { BN_sqr(r.raw(), self.raw(), ctx) == 1 })
+            with_bn_in_ctx!(r, ctx, { ffi::BN_sqr(r.raw(), self.raw(), ctx) == 1 })
         }
     }
 
     pub fn checked_nnmod(&self, n: &BigNum) -> Result<BigNum, SslError> {
         unsafe {
-            with_bn_in_ctx!(r, ctx, { BN_nnmod(r.raw(), self.raw(), n.raw(), ctx) == 1 })
+            with_bn_in_ctx!(r, ctx, { ffi::BN_nnmod(r.raw(), self.raw(), n.raw(), ctx) == 1 })
         }
     }
 
     pub fn checked_mod_add(&self, a: &BigNum, n: &BigNum) -> Result<BigNum, SslError> {
         unsafe {
-            with_bn_in_ctx!(r, ctx, { BN_mod_add(r.raw(), self.raw(), a.raw(), n.raw(), ctx) == 1 })
+            with_bn_in_ctx!(r, ctx, { ffi::BN_mod_add(r.raw(), self.raw(), a.raw(), n.raw(), ctx) == 1 })
         }
     }
 
     pub fn checked_mod_sub(&self, a: &BigNum, n: &BigNum) -> Result<BigNum, SslError> {
         unsafe {
-            with_bn_in_ctx!(r, ctx, { BN_mod_sub(r.raw(), self.raw(), a.raw(), n.raw(), ctx) == 1 })
+            with_bn_in_ctx!(r, ctx, { ffi::BN_mod_sub(r.raw(), self.raw(), a.raw(), n.raw(), ctx) == 1 })
         }
     }
 
     pub fn checked_mod_mul(&self, a: &BigNum, n: &BigNum) -> Result<BigNum, SslError> {
         unsafe {
-            with_bn_in_ctx!(r, ctx, { BN_mod_mul(r.raw(), self.raw(), a.raw(), n.raw(), ctx) == 1 })
+            with_bn_in_ctx!(r, ctx, { ffi::BN_mod_mul(r.raw(), self.raw(), a.raw(), n.raw(), ctx) == 1 })
         }
     }
 
     pub fn checked_mod_sqr(&self, n: &BigNum) -> Result<BigNum, SslError> {
         unsafe {
-            with_bn_in_ctx!(r, ctx, { BN_mod_sqr(r.raw(), self.raw(), n.raw(), ctx) == 1 })
+            with_bn_in_ctx!(r, ctx, { ffi::BN_mod_sqr(r.raw(), self.raw(), n.raw(), ctx) == 1 })
         }
     }
 
     pub fn checked_exp(&self, p: &BigNum) -> Result<BigNum, SslError> {
         unsafe {
-            with_bn_in_ctx!(r, ctx, { BN_exp(r.raw(), self.raw(), p.raw(), ctx) == 1 })
+            with_bn_in_ctx!(r, ctx, { ffi::BN_exp(r.raw(), self.raw(), p.raw(), ctx) == 1 })
         }
     }
 
     pub fn checked_mod_exp(&self, p: &BigNum, n: &BigNum) -> Result<BigNum, SslError> {
         unsafe {
-            with_bn_in_ctx!(r, ctx, { BN_mod_exp(r.raw(), self.raw(), p.raw(), n.raw(), ctx) == 1 })
+            with_bn_in_ctx!(r, ctx, { ffi::BN_mod_exp(r.raw(), self.raw(), p.raw(), n.raw(), ctx) == 1 })
         }
     }
 
     pub fn checked_mod_inv(&self, n: &BigNum) -> Result<BigNum, SslError> {
         unsafe {
-            with_bn_in_ctx!(r, ctx, { !BN_mod_inverse(r.raw(), self.raw(), n.raw(), ctx).is_null() })
+            with_bn_in_ctx!(r, ctx, { !ffi::BN_mod_inverse(r.raw(), self.raw(), n.raw(), ctx).is_null() })
         }
     }
 
     pub fn checked_gcd(&self, a: &BigNum) -> Result<BigNum, SslError> {
         unsafe {
-            with_bn_in_ctx!(r, ctx, { BN_gcd(r.raw(), self.raw(), a.raw(), ctx) == 1 })
+            with_bn_in_ctx!(r, ctx, { ffi::BN_gcd(r.raw(), self.raw(), a.raw(), ctx) == 1 })
         }
     }
 
@@ -244,7 +168,7 @@ impl BigNum {
                 let add_arg = add.map(|a| a.raw()).unwrap_or(ptr::mut_null());
                 let rem_arg = rem.map(|r| r.raw()).unwrap_or(ptr::mut_null());
 
-                BN_generate_prime_ex(r.raw(), bits as c_int, safe as c_int, add_arg, rem_arg, ptr::null()) == 1
+                ffi::BN_generate_prime_ex(r.raw(), bits as c_int, safe as c_int, add_arg, rem_arg, ptr::null()) == 1
             })
         }
     }
@@ -252,7 +176,7 @@ impl BigNum {
     pub fn is_prime(&self, checks: i32) -> Result<bool, SslError> {
         unsafe {
             with_ctx!(ctx, {
-                Ok(BN_is_prime_ex(self.raw(), checks as c_int, ctx, ptr::null()) == 1)
+                Ok(ffi::BN_is_prime_ex(self.raw(), checks as c_int, ctx, ptr::null()) == 1)
             })
         }
     }
@@ -260,38 +184,38 @@ impl BigNum {
     pub fn is_prime_fast(&self, checks: i32, do_trial_division: bool) -> Result<bool, SslError> {
         unsafe {
             with_ctx!(ctx, {
-                Ok(BN_is_prime_fasttest_ex(self.raw(), checks as c_int, ctx, do_trial_division as c_int, ptr::null()) == 1)
+                Ok(ffi::BN_is_prime_fasttest_ex(self.raw(), checks as c_int, ctx, do_trial_division as c_int, ptr::null()) == 1)
             })
         }
     }
 
     pub fn checked_new_random(bits: i32, prop: RNGProperty, odd: bool) -> Result<BigNum, SslError> {
         unsafe {
-            with_bn_in_ctx!(r, ctx, { BN_rand(r.raw(), bits as c_int, prop as c_int, odd as c_int) == 1 })
+            with_bn_in_ctx!(r, ctx, { ffi::BN_rand(r.raw(), bits as c_int, prop as c_int, odd as c_int) == 1 })
         }
     }
 
     pub fn checked_new_pseudo_random(bits: i32, prop: RNGProperty, odd: bool) -> Result<BigNum, SslError> {
         unsafe {
-            with_bn_in_ctx!(r, ctx, { BN_pseudo_rand(r.raw(), bits as c_int, prop as c_int, odd as c_int) == 1 })
+            with_bn_in_ctx!(r, ctx, { ffi::BN_pseudo_rand(r.raw(), bits as c_int, prop as c_int, odd as c_int) == 1 })
         }
     }
 
     pub fn checked_rand_in_range(&self) -> Result<BigNum, SslError> {
         unsafe {
-            with_bn_in_ctx!(r, ctx, { BN_rand_range(r.raw(), self.raw()) == 1 })
+            with_bn_in_ctx!(r, ctx, { ffi::BN_rand_range(r.raw(), self.raw()) == 1 })
         }
     }
 
     pub fn checked_pseudo_rand_in_range(&self) -> Result<BigNum, SslError> {
         unsafe {
-            with_bn_in_ctx!(r, ctx, { BN_pseudo_rand_range(r.raw(), self.raw()) == 1 })
+            with_bn_in_ctx!(r, ctx, { ffi::BN_pseudo_rand_range(r.raw(), self.raw()) == 1 })
         }
     }
 
     pub fn set_bit(&mut self, n: i32) -> Result<(), SslError> {
         unsafe {
-            if BN_set_bit(self.raw(), n as c_int) == 1 {
+            if ffi::BN_set_bit(self.raw(), n as c_int) == 1 {
                 Ok(())
             } else {
                 Err(SslError::get())
@@ -301,7 +225,7 @@ impl BigNum {
 
     pub fn clear_bit(&mut self, n: i32) -> Result<(), SslError> {
         unsafe {
-            if BN_clear_bit(self.raw(), n as c_int) == 1 {
+            if ffi::BN_clear_bit(self.raw(), n as c_int) == 1 {
                 Ok(())
             } else {
                 Err(SslError::get())
@@ -311,13 +235,13 @@ impl BigNum {
 
     pub fn is_bit_set(&self, n: i32) -> bool {
         unsafe {
-            BN_is_bit_set(self.raw(), n as c_int) == 1
+            ffi::BN_is_bit_set(self.raw(), n as c_int) == 1
         }
     }
 
     pub fn mask_bits(&mut self, n: i32) -> Result<(), SslError> {
         unsafe {
-            if BN_mask_bits(self.raw(), n as c_int) == 1 {
+            if ffi::BN_mask_bits(self.raw(), n as c_int) == 1 {
                 Ok(())
             } else {
                 Err(SslError::get())
@@ -327,67 +251,67 @@ impl BigNum {
 
     pub fn checked_shl1(&self) -> Result<BigNum, SslError> {
         unsafe {
-            with_bn!(r, { BN_lshift1(r.raw(), self.raw()) == 1 })
+            with_bn!(r, { ffi::BN_lshift1(r.raw(), self.raw()) == 1 })
         }
     }
 
     pub fn checked_shr1(&self) -> Result<BigNum, SslError> {
         unsafe {
-            with_bn!(r, { BN_rshift1(r.raw(), self.raw()) == 1 })
+            with_bn!(r, { ffi::BN_rshift1(r.raw(), self.raw()) == 1 })
         }
     }
 
     pub fn checked_add(&self, a: &BigNum) -> Result<BigNum, SslError> {
         unsafe {
-            with_bn!(r, { BN_add(r.raw(), self.raw(), a.raw()) == 1 })
+            with_bn!(r, { ffi::BN_add(r.raw(), self.raw(), a.raw()) == 1 })
         }
     }
 
     pub fn checked_sub(&self, a: &BigNum) -> Result<BigNum, SslError> {
         unsafe {
-            with_bn!(r, { BN_sub(r.raw(), self.raw(), a.raw()) == 1 })
+            with_bn!(r, { ffi::BN_sub(r.raw(), self.raw(), a.raw()) == 1 })
         }
     }
 
     pub fn checked_mul(&self, a: &BigNum) -> Result<BigNum, SslError> {
         unsafe {
-            with_bn_in_ctx!(r, ctx, { BN_mul(r.raw(), self.raw(), a.raw(), ctx) == 1 })
+            with_bn_in_ctx!(r, ctx, { ffi::BN_mul(r.raw(), self.raw(), a.raw(), ctx) == 1 })
         }
     }
 
     pub fn checked_div(&self, a: &BigNum) -> Result<BigNum, SslError> {
         unsafe {
-            with_bn_in_ctx!(r, ctx, { BN_div(r.raw(), ptr::mut_null(), self.raw(), a.raw(), ctx) == 1 })
+            with_bn_in_ctx!(r, ctx, { ffi::BN_div(r.raw(), ptr::mut_null(), self.raw(), a.raw(), ctx) == 1 })
         }
     }
 
     pub fn checked_mod(&self, a: &BigNum) -> Result<BigNum, SslError> {
         unsafe {
-            with_bn_in_ctx!(r, ctx, { BN_div(ptr::mut_null(), r.raw(), self.raw(), a.raw(), ctx) == 1 })
+            with_bn_in_ctx!(r, ctx, { ffi::BN_div(ptr::mut_null(), r.raw(), self.raw(), a.raw(), ctx) == 1 })
         }
     }
 
     pub fn checked_shl(&self, a: &i32) -> Result<BigNum, SslError> {
         unsafe {
-            with_bn!(r, { BN_lshift(r.raw(), self.raw(), *a as c_int) == 1 })
+            with_bn!(r, { ffi::BN_lshift(r.raw(), self.raw(), *a as c_int) == 1 })
         }
     }
 
     pub fn checked_shr(&self, a: &i32) -> Result<BigNum, SslError> {
         unsafe {
-            with_bn!(r, { BN_rshift(r.raw(), self.raw(), *a as c_int) == 1 })
+            with_bn!(r, { ffi::BN_rshift(r.raw(), self.raw(), *a as c_int) == 1 })
         }
     }
 
     pub fn negate(&mut self) {
         unsafe {
-            BN_set_negative(self.raw(), !self.is_negative() as c_int)
+            ffi::BN_set_negative(self.raw(), !self.is_negative() as c_int)
         }
     }
 
     pub fn abs_cmp(&self, oth: BigNum) -> Ordering {
         unsafe {
-            let res = BN_ucmp(self.raw(), oth.raw()) as i32;
+            let res = ffi::BN_ucmp(self.raw(), oth.raw()) as i32;
             if res < 0 {
                 Less
             } else if res > 0 {
@@ -406,7 +330,7 @@ impl BigNum {
 
     pub fn num_bits(&self) -> i32 {
         unsafe {
-            BN_num_bits(self.raw()) as i32
+            ffi::BN_num_bits(self.raw()) as i32
         }
     }
 
@@ -414,7 +338,7 @@ impl BigNum {
         (self.num_bits() + 7) / 8
     }
 
-    unsafe fn raw(&self) -> *mut BIGNUM {
+    unsafe fn raw(&self) -> *mut ffi::BIGNUM {
         let BigNum(n) = *self;
         n
     }
@@ -423,7 +347,7 @@ impl BigNum {
         let size = self.num_bytes() as uint;
         let mut v = Vec::with_capacity(size);
         unsafe {
-            BN_bn2bin(self.raw(), v.as_mut_ptr());
+            ffi::BN_bn2bin(self.raw(), v.as_mut_ptr());
             v.set_len(size);
         }
         v
@@ -431,11 +355,11 @@ impl BigNum {
 
     pub fn to_dec_str(&self) -> String {
         unsafe {
-            let buf = BN_bn2dec(self.raw());
+            let buf = ffi::BN_bn2dec(self.raw());
             assert!(!buf.is_null());
             let c_str = CString::new(buf, false);
             let str = c_str.as_str().unwrap().to_string();
-            CRYPTO_free(buf);
+            ffi::CRYPTO_free(buf);
             str
         }
     }
@@ -459,7 +383,7 @@ impl Zero for BigNum {
     }
     fn is_zero(&self) -> bool {
         unsafe {
-            BN_is_zero(self.raw()) == 1
+            ffi::BN_is_zero(self.raw()) == 1
         }
     }
 }
@@ -468,7 +392,7 @@ impl Eq for BigNum { }
 impl PartialEq for BigNum {
     fn eq(&self, oth: &BigNum) -> bool {
         unsafe {
-            BN_cmp(self.raw(), oth.raw()) == 0
+            ffi::BN_cmp(self.raw(), oth.raw()) == 0
         }
     }
 }
@@ -482,7 +406,7 @@ impl Ord for BigNum {
 impl PartialOrd for BigNum {
     fn partial_cmp(&self, oth: &BigNum) -> Option<Ordering> {
         unsafe {
-            let v = BN_cmp(self.raw(), oth.raw());
+            let v = ffi::BN_cmp(self.raw(), oth.raw());
             let ret =
                 if v == 0 {
                     Equal
@@ -500,18 +424,15 @@ impl Drop for BigNum {
     fn drop(&mut self) {
         unsafe {
             if !self.raw().is_null() {
-                BN_clear_free(self.raw());
+                ffi::BN_clear_free(self.raw());
             }
         }
     }
 }
 
 pub mod unchecked {
-    use super::{BIGNUM, BigNum};
-
-    extern {
-        fn BN_dup(n: *mut BIGNUM) -> *mut BIGNUM;
-    }
+    use ffi;
+    use super::{BigNum};
 
     impl Add<BigNum, BigNum> for BigNum {
         fn add(&self, oth: &BigNum) -> BigNum {
@@ -558,7 +479,7 @@ pub mod unchecked {
     impl Clone for BigNum {
         fn clone(&self) -> BigNum {
             unsafe {
-                let r = BN_dup(self.raw());
+                let r = ffi::BN_dup(self.raw());
                 if r.is_null() {
                     fail!("Unexpected null pointer from BN_dup(..)")
                 } else {