Add "lax DER" support; bump major version number for recent build system changes

Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 
 name = "secp256k1"
-version = "0.3.3"
+version = "0.4.0"
 authors = [ "Dawid Ciężarkiewicz <dpc@ucore.info>",
             "Andrew Poelstra <apoelstra@wpsoftware.net>" ]
 license = "CC0-1.0"

build.rs

@@ -24,10 +24,10 @@
 extern crate gcc;
 
 fn main() {
-    gcc::Config::new()
+    let mut base_config = gcc::Config::new();
-                .file("depend/secp256k1/src/secp256k1.c")
+    base_config.include("depend/secp256k1/")
-                .include("depend/secp256k1/")
                .include("depend/secp256k1/src")
+               .flag("-g")
                // TODO these three should be changed to use libgmp, at least until secp PR 290 is merged
                .define("USE_NUM_NONE", Some("1"))
                .define("USE_FIELD_INV_BUILTIN", Some("1"))
@@ -38,7 +38,11 @@ fn main() {
                .define("USE_ENDOMORPHISM", Some("1"))
                // These all are OK.
                .define("ENABLE_MODULE_ECDH", Some("1"))
-                .define("ENABLE_MODULE_RECOVERY", Some("1"))
+               .define("ENABLE_MODULE_RECOVERY", Some("1"));
+
+    // secp256k1
+    base_config.file("depend/secp256k1/src/laxder_shim.c")
+               .file("depend/secp256k1/src/secp256k1.c")
                .compile("libsecp256k1.a");
 }
 

depend/secp256k1/src/laxder_shim.c

@@ -0,0 +1,21 @@
+/* Bitcoin secp256k1 bindings
+ * Written in 2015 by
+ *   Andrew Poelstra
+ *
+ * To the extent possible under law, the author(s) have dedicated all
+ * copyright and related and neighboring rights to this software to
+ * the public domain worldwide. This software is distributed without
+ * any warranty.
+ *
+ * You should have received a copy of the CC0 Public Domain Dedication
+ * along with this software.
+ * If not, see <http://creativecommons.org/publicdomain/zero/1.0/>.
+ */
+
+#include "contrib/lax_der_parsing.h"
+
+int secp256k1_ecdsa_signature_parse_der_lax_(const secp256k1_context* ctx, secp256k1_ecdsa_signature* sig, const unsigned char *input, size_t inputlen) {
+    return secp256k1_ecdsa_signature_parse_der_lax(ctx, sig, input, inputlen);
+}
+
+

src/ffi.rs

@@ -154,6 +154,10 @@ extern "C" {
                                                input: *const c_uchar, in_len: size_t)
                                                -> c_int;
 
+    pub fn secp256k1_ecdsa_signature_parse_der_lax_(cx: Context, sig: *mut Signature,
+                                                    input: *const c_uchar, in_len: size_t)
+                                                    -> c_int;
+
     pub fn secp256k1_ecdsa_signature_serialize_der(cx: Context, output: *const c_uchar,
                                                    out_len: *const size_t, sig: *const Signature)
                                                    -> c_int;

src/lib.rs

@@ -99,6 +99,22 @@ impl Signature {
         }
     }
 
+    /// Converts a "lax DER"-encoded byte slice to a signature. This is basically
+    /// only useful for validating signatures in the Bitcoin blockchain from before
+    /// 2016. It should never be used in new applications. This library does not
+    /// support serializing to this "format"
+    pub fn from_der_lax(secp: &Secp256k1, data: &[u8]) -> Result<Signature, Error> {
+        unsafe {
+            let mut ret = ffi::Signature::blank();
+            if ffi::secp256k1_ecdsa_signature_parse_der_lax_(secp.ctx, &mut ret,
+                                                             data.as_ptr(), data.len() as libc::size_t) == 1 {
+                Ok(Signature(ret))
+            } else {
+                Err(Error::InvalidSignature)
+            }
+        }
+    }
+
     /// Obtains a raw pointer suitable for use with FFI functions
     #[inline]
     pub fn as_ptr(&self) -> *const ffi::Signature {
@@ -484,6 +500,7 @@ impl Secp256k1 {
 mod tests {
     use rand::{Rng, thread_rng};
     use std::ptr;
+    use serialize::hex::FromHex;
 
     use key::{SecretKey, PublicKey};
     use super::constants;
@@ -491,6 +508,8 @@ mod tests {
     use super::Error::{InvalidMessage, InvalidPublicKey, IncorrectSignature, InvalidSignature,
                        IncapableContext};
 
+    macro_rules! hex (($hex:expr) => ($hex.from_hex().unwrap()));
+
     #[test]
     fn capabilities() {
         let none = Secp256k1::with_caps(ContextFlag::None);
@@ -610,6 +629,14 @@ mod tests {
          }
     }
 
+    #[test]
+    fn signature_lax_der() {
+        let secp = Secp256k1::without_caps();
+        let sig = hex!("304402204c2dd8a9b6f8d425fcd8ee9a20ac73b619906a6367eac6cb93e70375225ec0160220356878eff111ff3663d7e6bf08947f94443845e0dcc54961664d922f7660b80c01");
+        assert!(Signature::from_der(&secp, &sig[..]).is_err());
+        assert!(Signature::from_der_lax(&secp, &sig[..]).is_ok());
+    }
+
     #[test]
     fn sign_and_verify() {
         let mut s = Secp256k1::new();