Initial parser.

src/lib.rs

@@ -0,0 +1,753 @@
+extern crate num;
+#[cfg(test)]
+#[macro_use]
+extern crate quickcheck;
+
+use num::{BigInt,BigUint,FromPrimitive,One,ToPrimitive,Zero};
+use std::iter::FromIterator;
+use std::mem::size_of;
+
+#[derive(Clone,Debug,PartialEq)]
+pub enum ASN1Block {
+    Boolean(ASN1Class, bool),
+    Integer(ASN1Class, BigInt),
+    BitString(ASN1Class, usize, Vec<u8>),
+    OctetString(ASN1Class, Vec<u8>),
+    Null(ASN1Class),
+    ObjectIdentifier(ASN1Class, Vec<BigUint>),
+    IA5String(ASN1Class, String),
+    UTF8String(ASN1Class, String),
+    Sequence(ASN1Class, Vec<ASN1Block>),
+    Set(ASN1Class, Vec<ASN1Block>),
+    Unknown(ASN1Class, BigUint, Vec<u8>)
+}
+
+#[derive(Clone,Copy,Debug,PartialEq)]
+pub enum ASN1Class { Universal, Application, ContextSpecific, Private }
+
+#[derive(Clone,Debug,PartialEq)]
+pub enum ASN1DecodeErr {
+    EmptyBuffer,
+    BadBooleanLength,
+    LengthTooLarge,
+    UTF8DecodeFailure
+}
+
+#[derive(Clone,Debug,PartialEq)]
+pub enum ASN1EncodeErr {
+    ObjectIdentHasTooFewFields,
+    ObjectIdentVal1TooLarge,
+    ObjectIdentVal2TooLarge
+}
+
+pub fn from_der(i: &[u8]) -> Result<Vec<ASN1Block>,ASN1DecodeErr> {
+    let mut result: Vec<ASN1Block> = Vec::new();
+    let mut index:  usize          = 0;
+    let     len                    = i.len();
+
+    while index < len {
+        let (tag, class) = decode_tag(i, &mut index);
+        let len = decode_length(i, &mut index)?;
+        let body = &i[index .. (index + len)];
+
+        match tag.to_u8() {
+            // BOOLEAN
+            Some(0x01) => {
+                if len != 1 {
+                    return Err(ASN1DecodeErr::BadBooleanLength);
+                }
+                result.push(ASN1Block::Boolean(class, body[0] != 0));
+            }
+            // INTEGER
+            Some(0x02) => {
+                let res = BigInt::from_signed_bytes_be(&body);
+                result.push(ASN1Block::Integer(class, res));
+            }
+            // BIT STRING
+            Some(0x03) if body.len() == 0 => {
+                result.push(ASN1Block::BitString(class, 0, Vec::new()))
+            }
+            Some(0x03) => {
+                let bits = (&body[1..]).to_vec();
+                let nbits = (bits.len() * 8) - (body[0] as usize);
+                result.push(ASN1Block::BitString(class, nbits, bits));
+            }
+            // OCTET STRING
+            Some(0x04) => {
+                result.push(ASN1Block::OctetString(class, body.to_vec()));
+            }
+            // NULL
+            Some(0x05) => {
+                result.push(ASN1Block::Null(class));
+            }
+            // OBJECT IDENTIFIER
+            Some(0x06) => {
+                let mut value1 = BigUint::zero();
+                let mut value2 = BigUint::from_u8(body[0]).unwrap();
+                let mut oidres = Vec::new();
+                let mut bindex = 1;
+
+                if body[0] >= 40 {
+                    if body[0] < 80 {
+                        value1 = BigUint::one();
+                        value2 = value2 - BigUint::from_u8(40).unwrap();
+                    } else {
+                        value1 = BigUint::from_u8(2).unwrap();
+                        value2 = value2 - BigUint::from_u8(80).unwrap();
+                    }
+                }
+
+                oidres.push(value1);
+                oidres.push(value2);
+                while bindex < body.len() {
+                    oidres.push(decode_base127(body, &mut bindex));
+                }
+
+                result.push(ASN1Block::ObjectIdentifier(class, oidres));
+            }
+            // UTF8STRING
+            Some(0x0C) => {
+                match String::from_utf8(body.to_vec()) {
+                    Ok(v) =>
+                        result.push(ASN1Block::UTF8String(class, v)),
+                    Err(_) =>
+                        return Err(ASN1DecodeErr::UTF8DecodeFailure)
+                }
+            }
+            // SEQUENCE
+            Some(0x10) => {
+                match from_der(body) {
+                    Ok(items) =>
+                        result.push(ASN1Block::Sequence(class, items)),
+                    Err(e) =>
+                        return Err(e)
+                }
+            }
+            // SET
+            Some(0x11) => {
+                match from_der(body) {
+                    Ok(items) =>
+                        result.push(ASN1Block::Set(class, items)),
+                    Err(e) =>
+                        return Err(e)
+                }
+            }
+            // IA5 (ASCII) STRING
+            Some(0x16) => {
+                let val = body.iter().map(|x| *x as char);
+                result.push(ASN1Block::IA5String(class, String::from_iter(val)))
+            }
+            // Dunno.
+            _ => {
+                result.push(ASN1Block::Unknown(class, tag, body.to_vec()));
+            }
+        }
+        index += len;
+    }
+
+    if result.is_empty() {
+        Err(ASN1DecodeErr::EmptyBuffer)
+    } else {
+        Ok(result)
+    }
+}
+
+fn decode_tag(i: &[u8], index: &mut usize) -> (BigUint, ASN1Class) {
+    let tagbyte = i[*index];
+    let class   = decode_class(tagbyte);
+    let basetag = tagbyte & 0b11111;
+
+    *index += 1;
+    if basetag == 0b11111 {
+        let res = decode_base127(i, index);
+        (res, class)
+    } else {
+        (BigUint::from(basetag), class)
+    }
+}
+
+fn decode_base127(i: &[u8], index: &mut usize) -> BigUint {
+    let mut res = BigUint::zero();
+
+    loop {
+        let nextbyte = i[*index];
+
+        *index += 1;
+        res = (res << 7) + BigUint::from(nextbyte & 0x7f);
+        if (nextbyte & 0x80) == 0 {
+            return res;
+        }
+    }
+}
+
+fn decode_class(i: u8) -> ASN1Class {
+    match i >> 6 {
+        0b00 => ASN1Class::Universal,
+        0b01 => ASN1Class::Application,
+        0b10 => ASN1Class::ContextSpecific,
+        0b11 => ASN1Class::Private,
+        _    => panic!("The universe is broken.")
+    }
+}
+
+fn decode_length(i: &[u8], index: &mut usize) -> Result<usize,ASN1DecodeErr> {
+    let startbyte = i[*index];
+
+    // NOTE: Technically, this size can be much larger than a usize.
+    // However, our whole universe starts to break down if we get
+    // things that big. So we're boring, and only accept lengths
+    // that fit within a usize.
+    *index += 1;
+    if startbyte >= 0x80 {
+        let mut lenlen = (startbyte & 0x7f) as usize;
+        let mut res = 0;
+
+        if lenlen > size_of::<usize>() {
+            return Err(ASN1DecodeErr::LengthTooLarge);
+        }
+
+        while lenlen > 0 {
+            res = (res << 8) + (i[*index] as usize);
+
+            *index += 1;
+            lenlen -= 1;
+        }
+
+        Ok(res)
+    } else {
+        Ok(startbyte as usize)
+    }
+}
+
+pub fn to_der(i: &ASN1Block) -> Result<Vec<u8>,ASN1EncodeErr> {
+    match i {
+        // BOOLEAN
+        &ASN1Block::Boolean(cl, val) => {
+            let inttag = BigUint::one();
+            let mut tagbytes = encode_tag(cl, &inttag);
+            tagbytes.push(1);
+            tagbytes.push(if val { 0xFF } else { 0x00 });
+            Ok(tagbytes)
+        }
+        // INTEGER
+        &ASN1Block::Integer(cl, ref int) => {
+            let mut base = int.to_signed_bytes_be();
+            let mut lenbytes = encode_len(base.len());
+            let     inttag   = BigUint::from_u8(0x02).unwrap();
+            let mut tagbytes = encode_tag(cl, &inttag);
+
+            let mut result = Vec::new();
+            result.append(&mut tagbytes);
+            result.append(&mut lenbytes);
+            result.append(&mut base);
+            Ok(result)
+        }
+        // BIT STRING
+        &ASN1Block::BitString(cl, bits, ref vs) => {
+            let inttag = BigUint::from_u8(0x03).unwrap();
+            let mut tagbytes = encode_tag(cl, &inttag);
+
+            if bits == 0 {
+                tagbytes.push(0);
+                Ok(tagbytes)
+            } else {
+                let mut lenbytes = encode_len(vs.len() + 1);
+                let     nbits    = (vs.len() * 8) - bits;
+
+                let mut result = Vec::new();
+                result.append(&mut tagbytes);
+                result.append(&mut lenbytes);
+                result.push(nbits as u8);
+                result.extend(vs.iter());
+                Ok(result)
+            }
+        }
+        // OCTET STRING
+        &ASN1Block::OctetString(cl, ref bytes) => {
+            let inttag = BigUint::from_u8(0x04).unwrap();
+            let mut tagbytes = encode_tag(cl, &inttag);
+            let mut lenbytes = encode_len(bytes.len());
+
+            let mut result = Vec::new();
+            result.append(&mut tagbytes);
+            result.append(&mut lenbytes);
+            result.extend(bytes.iter());
+            Ok(result)
+        }
+        // NULL
+        &ASN1Block::Null(cl) => {
+            let inttag = BigUint::from_u8(0x05).unwrap();
+            let mut result = encode_tag(cl, &inttag);
+            result.push(0);
+            Ok(result)
+        }
+        // OBJECT IDENTIFIER
+        &ASN1Block::ObjectIdentifier(cl, ref nums) => {
+            match (nums.get(0), nums.get(1)) {
+                (Some(v1), Some(v2)) => {
+                    let two = BigUint::from_u8(2).unwrap();
+
+                    // first, validate that the first two items meet spec
+                    if v1 > &two {
+                        return Err(ASN1EncodeErr::ObjectIdentVal1TooLarge)
+                    }
+
+                    let u175 = BigUint::from_u8(175).unwrap();
+                    let u39 = BigUint::from_u8(39).unwrap();
+                    let bound = if v1 == &two { u175 } else { u39 };
+
+                    if v2 > &bound {
+                        return Err(ASN1EncodeErr::ObjectIdentVal2TooLarge);
+                    }
+
+                    // the following unwraps must be safe, based on the 
+                    // validation above.
+                    let value1 = v1.to_u8().unwrap();
+                    let value2 = v2.to_u8().unwrap();
+                    let byte1  = (value1 * 40) + value2;
+
+                    // now we can build all the rest of the body
+                    let mut body = vec![byte1];
+                    for num in nums.iter().skip(2) {
+                        let mut local = encode_base127(&num);
+                        body.append(&mut local);
+                    }
+
+                    // now that we have the body, we can build the header
+                    let inttag = BigUint::from_u8(0x06).unwrap();
+                    let mut result = encode_tag(cl, &inttag);
+                    let mut lenbytes = encode_len(body.len());
+
+                    result.append(&mut lenbytes);
+                    result.append(&mut body);
+
+                    Ok(result)
+                }
+                _ => {
+                    Err(ASN1EncodeErr::ObjectIdentHasTooFewFields)
+                }
+            }
+        }
+        // SEQUENCE
+        &ASN1Block::Sequence(cl, ref items) => {
+            let mut body = Vec::new();
+
+            // put all the subsequences into a block
+            for x in items.iter() {
+                let mut bytes = to_der(x)?;
+                body.append(&mut bytes);
+            }
+
+            let inttag = BigUint::from_u8(0x10).unwrap();
+            let mut lenbytes = encode_len(body.len());
+            let mut tagbytes = encode_tag(cl, &inttag);
+
+            let mut res = Vec::new();
+            res.append(&mut tagbytes);
+            res.append(&mut lenbytes);
+            res.append(&mut body);
+            Ok(res)
+        }
+        // SET
+        &ASN1Block::Set(cl, ref items) => {
+            let mut body = Vec::new();
+
+            // put all the subsequences into a block
+            for x in items.iter() {
+                let mut bytes = to_der(x)?;
+                body.append(&mut bytes);
+            }
+
+            let inttag = BigUint::from_u8(0x11).unwrap();
+            let mut lenbytes = encode_len(body.len());
+            let mut tagbytes = encode_tag(cl, &inttag);
+
+            let mut res = Vec::new();
+            res.append(&mut tagbytes);
+            res.append(&mut lenbytes);
+            res.append(&mut body);
+            Ok(res)
+        }
+        // IA5String
+        &ASN1Block::IA5String(cl, ref str) => {
+            let mut body = Vec::new();
+
+            for c in str.chars() {
+                body.push(c as u8);
+            }
+
+            let inttag = BigUint::from_u8(0x16).unwrap();
+            let mut lenbytes = encode_len(body.len());
+            let mut tagbytes = encode_tag(cl, &inttag);
+
+            let mut res = Vec::new();
+            res.append(&mut tagbytes);
+            res.append(&mut lenbytes);
+            res.append(&mut body);
+            Ok(res)
+        }
+        // UTF8STRING
+        &ASN1Block::UTF8String(cl, ref val) => {
+            let mut body = val.clone().into_bytes();
+            let inttag = BigUint::from_u8(0x0C).unwrap();
+            let mut lenbytes = encode_len(body.len());
+            let mut tagbytes = encode_tag(cl, &inttag);
+
+            let mut res = Vec::new();
+            res.append(&mut tagbytes);
+            res.append(&mut lenbytes);
+            res.append(&mut body);
+            Ok(res)
+        }
+        // Unknown blocks
+        &ASN1Block::Unknown(class, ref tag, ref bytes) => {
+            let mut tagbytes = encode_tag(class, &tag);
+            let mut lenbytes = encode_len(bytes.len());
+
+            let mut res = Vec::new();
+            res.append(&mut tagbytes);
+            res.append(&mut lenbytes);
+            res.extend(bytes.iter());
+            Ok(res)
+        }
+    }
+}
+
+fn encode_tag(c: ASN1Class, t: &BigUint) -> Vec<u8> {
+    let cbyte = encode_class(c);
+
+    match t.to_u8() {
+        Some(x) if x < 31 => {
+            vec![cbyte | x]
+        }
+        _ => {
+            let mut res = encode_base127(t);
+            res.insert(0, cbyte | 0b00011111);
+            res
+        }
+    }
+}
+
+fn encode_base127(v: &BigUint) -> Vec<u8> {
+    let mut acc = v.clone();
+    let mut res = Vec::new();
+    let u128 = BigUint::from_u8(128).unwrap();
+    let zero = BigUint::zero();
+
+    while acc > zero {
+        // we build this vector backwards
+        let digit = &acc % &u128;
+        acc = acc >> 7;
+
+        match digit.to_u8() {
+            None =>
+                panic!("7 bits don't fit into 8, cause ..."),
+            Some(x) if res.is_empty() =>
+                res.push(x),
+            Some(x) =>
+                res.push(x | 0x80)
+        }
+    }
+
+    res.reverse();
+    res
+}
+
+fn encode_class(c: ASN1Class) -> u8 {
+    match c {
+        ASN1Class::Universal       => 0b00000000,
+        ASN1Class::Application     => 0b01000000,
+        ASN1Class::ContextSpecific => 0b10000000,
+        ASN1Class::Private         => 0b11000000,
+    }
+}
+
+
+fn encode_len(x: usize) -> Vec<u8> {
+    if x < 128 {
+        vec![x as u8]
+    } else {
+        let mut bstr = Vec::new();
+        let mut work = x;
+
+        // convert this into bytes, backwards
+        while work > 0 {
+            bstr.push(work as u8);
+            work = work >> 8;
+        }
+
+        // encode the front of the length
+        let len = bstr.len() as u8;
+        bstr.push(len | 0x80);
+
+        // and then reverse it into the right order
+        bstr.reverse();
+        bstr
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use quickcheck::{Arbitrary,Gen};
+    use std::fs::File;
+    use std::io::Read;
+    use super::*;
+
+    impl Arbitrary for ASN1Class {
+        fn arbitrary<G: Gen>(g: &mut G) -> ASN1Class {
+            match g.gen::<u8>() % 4 {
+                0 => ASN1Class::Private,
+                1 => ASN1Class::ContextSpecific,
+                2 => ASN1Class::Universal,
+                3 => ASN1Class::Application,
+                _ => panic!("I weep for a broken life.")
+            }
+        }
+    }
+
+    quickcheck! {
+        fn class_encdec_roundtrips(c: ASN1Class) -> bool {
+            c == decode_class(encode_class(c.clone()))
+        }
+
+        fn class_decenc_roundtrips(v: u8) -> bool {
+            (v & 0b11000000) == encode_class(decode_class(v))
+        }
+    }
+
+    #[derive(Clone,Debug)]
+    struct RandomUint {
+        x: BigUint
+    }
+
+    impl Arbitrary for RandomUint {
+        fn arbitrary<G: Gen>(g: &mut G) -> RandomUint {
+            let v = BigUint::from_u32(g.gen::<u32>()).unwrap();
+            RandomUint{ x: v }
+        }
+    }
+
+   quickcheck! {
+        fn tags_encdec_roundtrips(c: ASN1Class, t: RandomUint) -> bool {
+            let bytes = encode_tag(c, &t.x);
+            let mut zero = 0;
+            let (t2, c2) = decode_tag(&bytes[..], &mut zero);
+            (c == c2) && (t.x == t2)
+        }
+
+        fn len_encdec_roundtrips(l: usize) -> bool {
+            let bytes = encode_len(l);
+            let mut zero = 0;
+            match decode_length(&bytes[..], &mut zero) {
+                Err(_) => false,
+                Ok(l2) => l == l2
+            }
+        }
+    }
+
+    #[derive(Clone,Debug)]
+    struct RandomInt {
+        x: BigInt
+    }
+
+    impl Arbitrary for RandomInt {
+        fn arbitrary<G: Gen>(g: &mut G) -> RandomInt {
+            let v = BigInt::from_i64(g.gen::<i64>()).unwrap();
+            RandomInt{ x: v }
+        }
+    }
+
+    type ASN1BlockGen<G: Gen> = fn(&mut G, usize) -> ASN1Block;
+
+    fn arb_boolean<G: Gen>(g: &mut G, _d: usize) -> ASN1Block {
+        let c = ASN1Class::arbitrary(g);
+        let v = g.gen::<bool>();
+        ASN1Block::Boolean(c, v)
+    }
+
+    fn arb_integer<G: Gen>(g: &mut G, _d: usize) -> ASN1Block {
+        let c = ASN1Class::arbitrary(g);
+        let d = RandomInt::arbitrary(g);
+        ASN1Block::Integer(c, d.x)
+    }
+
+    fn arb_bitstr<G: Gen>(g: &mut G, _d: usize) -> ASN1Block {
+        let class = ASN1Class::arbitrary(g);
+        let size = g.gen::<u16>() as usize % 16;
+        let maxbits = (size as usize) * 8;
+        let modbits = g.gen::<u8>() as usize % 8;
+        let nbits = if modbits > maxbits
+                      { maxbits }
+                    else { maxbits - modbits };
+        let bytes = g.gen_iter::<u8>().take(size).collect();
+        ASN1Block::BitString(class, nbits, bytes)
+    }
+
+    fn arb_octstr<G: Gen>(g: &mut G, _d: usize) -> ASN1Block {
+        let class = ASN1Class::arbitrary(g);
+        let size = g.gen::<u16>() as usize % 16;
+        let bytes = g.gen_iter::<u8>().take(size).collect();
+        ASN1Block::OctetString(class, bytes)
+    }
+
+    fn arb_null<G: Gen>(g: &mut G, _d: usize) -> ASN1Block {
+        let class = ASN1Class::arbitrary(g);
+        ASN1Block::Null(class)
+    }
+
+    fn arb_objid<G: Gen>(g: &mut G, _d: usize) -> ASN1Block {
+        let     class = ASN1Class::arbitrary(g);
+        let     count = g.gen_range::<usize>(0, 40);
+        let     val1  = g.gen::<u8>() % 3;
+        let     v2mod = if val1 == 2 { 176 } else { 40 };
+        let     val2  = g.gen::<u8>() % v2mod;
+        let     v1    = BigUint::from_u8(val1).unwrap();
+        let     v2    = BigUint::from_u8(val2).unwrap();
+        let mut nums  = vec![v1, v2];
+
+        for _ in 0..count {
+            let num = RandomUint::arbitrary(g);
+            nums.push(num.x);
+        }
+
+        ASN1Block::ObjectIdentifier(class, nums)
+    }
+
+    fn arb_seq<G: Gen>(g: &mut G, d: usize) -> ASN1Block {
+        let class = ASN1Class::arbitrary(g);
+        let count = g.gen_range::<usize>(1, 64);
+        let mut items = Vec::new();
+
+        for _ in 0..count {
+            items.push(limited_arbitrary(g, d - 1));
+        }
+
+        ASN1Block::Sequence(class, items)
+    }
+
+    fn arb_set<G: Gen>(g: &mut G, d: usize) -> ASN1Block {
+        let class = ASN1Class::arbitrary(g);
+        let count = g.gen_range::<usize>(1, 64);
+        let mut items = Vec::new();
+
+        for _ in 0..count {
+            items.push(limited_arbitrary(g, d - 1));
+        }
+
+        ASN1Block::Set(class, items)
+    }
+
+    fn arb_ia5<G: Gen>(g: &mut G, _d: usize) -> ASN1Block {
+        let class = ASN1Class::arbitrary(g);
+        let count = g.gen_range::<usize>(0, 384);
+        let mut items = Vec::new();
+
+        for _ in 0..count {
+            items.push(g.gen::<u8>() as char);
+        }
+
+        ASN1Block::IA5String(class, String::from_iter(items.iter()))
+    }
+
+    fn arb_utf8<G: Gen>(g: &mut G, _d: usize) -> ASN1Block {
+        let class = ASN1Class::arbitrary(g);
+        let val = String::arbitrary(g);
+        ASN1Block::UTF8String(class, val)
+    }
+
+    fn arb_unknown<G: Gen>(g: &mut G, _d: usize) -> ASN1Block {
+        let class = ASN1Class::arbitrary(g);
+        let tag   = RandomUint::arbitrary(g);
+        let size  = g.gen_range::<usize>(0, 128);
+        let items = g.gen_iter::<u8>().take(size).collect();
+
+        ASN1Block::Unknown(class, tag.x, items)
+    }
+
+    fn limited_arbitrary<G: Gen>(g: &mut G, d: usize) -> ASN1Block {
+        let mut possibles: Vec<ASN1BlockGen<G>> =
+            vec![arb_boolean,
+                 arb_integer,
+                 arb_bitstr,
+                 arb_octstr,
+                 arb_null,
+                 arb_objid,
+                 arb_ia5,
+                 arb_utf8,
+                 arb_unknown];
+
+        if d > 0 {
+            possibles.push(arb_seq);
+            possibles.push(arb_set);
+        }
+
+        match g.choose(&possibles[..]) {
+            Some(f) => f(g, d),
+            None    => panic!("Couldn't generate arbitrary value.")
+        }
+    }
+
+    impl Arbitrary for ASN1Block {
+        fn arbitrary<G: Gen>(g: &mut G) -> ASN1Block {
+            limited_arbitrary(g, 2)
+        }
+    }
+
+    quickcheck! {
+        fn encode_decode_roundtrips(v: ASN1Block) -> bool {
+            match to_der(&v) {
+                Err(e) => {
+                    println!("Serialization error: {:?}", e);
+                    false
+                }
+                Ok(bytes) =>
+                    match from_der(&bytes[..]) {
+                        Err(e) => {
+                            println!("Parse error: {:?}", e);
+                            false
+                        }
+                        Ok(ref rvec) if rvec.len() == 1 => {
+                            let v2 = rvec.get(0).unwrap();
+                            if &v != v2 {
+                                println!("Original: {:?}", v);
+                                println!("Constructed: {:?}", v2);
+                            }
+                            &v == v2
+                        }
+                        Ok(_) => {
+                            println!("Too many results returned.");
+                            false
+                        }
+                    }
+            }
+        }
+    }
+
+    fn result_int(v: i16) -> Result<Vec<ASN1Block>,ASN1DecodeErr> {
+        let val = BigInt::from(v);
+        Ok(vec![ASN1Block::Integer(ASN1Class::Universal, val)])
+    }
+
+    #[test]
+    fn base_integer_tests() {
+        assert_eq!(from_der(&vec![0x02,0x01,0x00]), result_int(0));
+        assert_eq!(from_der(&vec![0x02,0x01,0x7F]), result_int(127));
+        assert_eq!(from_der(&vec![0x02,0x02,0x00,0x80]), result_int(128));
+        assert_eq!(from_der(&vec![0x02,0x02,0x01,0x00]), result_int(256));
+        assert_eq!(from_der(&vec![0x02,0x01,0x80]), result_int(-128));
+        assert_eq!(from_der(&vec![0x02,0x02,0xFF,0x7F]), result_int(-129));
+    }
+
+    fn can_parse(f: &str) -> Result<Vec<ASN1Block>,ASN1DecodeErr> {
+        let mut fd = File::open(f).unwrap();
+        let mut buffer = Vec::new();
+        fd.read_to_end(&mut buffer);
+        from_der(&buffer[..])
+    }
+
+    #[test]
+    fn x509_tests() {
+        assert!(can_parse("test/server.bin").is_ok());
+        assert!(can_parse("test/key.bin").is_ok());
+    }
+}