metainfo parsing

src/bencode/decode.rs

@@ -46,7 +46,7 @@ fn decode_object(buf: &mut Buffer) -> DecodeResult<Object> {
                 }
                 list.push(decode_object(buf)?);
             }
-            Ok(List::new(list))
+            Ok(List::wrap(list))
         }
         Some(b'd') => {
             buf.advance(1);
@@ -60,7 +60,7 @@ fn decode_object(buf: &mut Buffer) -> DecodeResult<Object> {
                 let val = decode_object(buf)?;
                 dict.insert(Bytes(key), val);
             }
-            Ok(Dict::new(dict))
+            Ok(Dict::wrap(dict))
         }
         _ => Err(DecodeError),
     }
@@ -84,7 +84,7 @@ fn _decode_int(buf: &mut Buffer, term: u8) -> DecodeResult<i64> {
 }
 
 fn decode_bytes(buf: &mut Buffer) -> DecodeResult<Object> {
-    _decode_bytes(buf).map(|bytes| Bytes::new(bytes))
+    _decode_bytes(buf).map(|bytes| Bytes::wrap(bytes))
 }
 
 fn _decode_bytes(buf: &mut Buffer) -> Result<Vec<u8>, DecodeError> {
@@ -116,7 +116,7 @@ fn test_int_neg() {
 fn test_bytes() {
     let mut buf = Buffer::new(b"5:hello");
 
-    assert_eq!(decode_bytes(&mut buf).unwrap(), Bytes::new(b"hello".to_vec()));
+    assert_eq!(decode_bytes(&mut buf).unwrap(), Bytes::wrap(b"hello".to_vec()));
     assert_eq!(buf.pos(), 7);
 }
 

src/bencode/encode.rs

@@ -57,7 +57,7 @@ fn test_int_neg() {
 fn test_bytes() {
     use bencode::Bytes;
 
-    assert_eq!(encode(Bytes::new(b"hello".to_vec())), b"5:hello");
+    assert_eq!(encode(Bytes::wrap(b"hello".to_vec())), b"5:hello");
 }
 
 #[test]
@@ -65,7 +65,7 @@ fn test_list() {
     use bencode::List;
 
     let list = vec![Object::Int(1), Object::Int(2), Object::Int(3)];
-    assert_eq!(encode(List::new(list)), b"li1ei2ei3ee");
+    assert_eq!(encode(List::wrap(list)), b"li1ei2ei3ee");
 }
 
 #[test]
@@ -75,5 +75,5 @@ fn test_dict() {
 
     let mut dict = BTreeMap::new();
     dict.insert(Bytes(b"hello".to_vec()), Object::Int(1337));
-    assert_eq!(encode(Dict::new(dict)), b"d5:helloi1337ee")
+    assert_eq!(encode(Dict::wrap(dict)), b"d5:helloi1337ee")
 }

src/bencode/mod.rs

@@ -87,8 +87,12 @@ impl fmt::Debug for Object {
 pub struct Bytes(Vec<u8>);
 
 impl Bytes {
-    pub fn new(bytes: Vec<u8>) -> Object {
-        Object::Bytes(Bytes(bytes))
+    pub fn new<A>(bytes: A) -> Bytes where A: Into<Vec<u8>> {
+        Bytes(bytes.into())
+    }
+
+    pub fn wrap<A>(bytes: A) -> Object where A: Into<Vec<u8>> {
+        Object::Bytes(Bytes(bytes.into()))
     }
 
     pub fn str(&self) -> Option<&str> {
@@ -140,7 +144,11 @@ impl<'a> AsBytes for &'a [u8] {
 pub struct List(Vec<Object>);
 
 impl List {
-    pub fn new(list: Vec<Object>) -> Object {
+    pub fn new() -> List {
+        List(Vec::new())
+    }
+
+    pub fn wrap(list: Vec<Object>) -> Object {
         Object::List(List(list))
     }
 }
@@ -163,7 +171,11 @@ impl DerefMut for List {
 pub struct Dict(BTreeMap<Bytes, Object>);
 
 impl Dict {
-    pub fn new(dict: BTreeMap<Bytes, Object>) -> Object {
+    pub fn new() -> Dict {
+        Dict(BTreeMap::new())
+    }
+
+    pub fn wrap(dict: BTreeMap<Bytes, Object>) -> Object {
         Object::Dict(Dict(dict))
     }
 

src/lib.rs

@@ -1,2 +1,3 @@
 pub mod bencode;
 pub mod buffer;
+pub mod metainfo;

src/metainfo.rs

@@ -0,0 +1,169 @@
+use std::path::PathBuf;
+
+use sha1::Sha1;
+
+use bencode::{encode, Object};
+
+macro_rules! ts {
+    ( $e:expr ) => {
+        match $e {
+            Some(x) => x,
+            None => return None,
+        }
+    }
+}
+
+#[derive(Debug)]
+pub struct Metainfo {
+    pub announce: String,
+    pub announce_list: Vec<Vec<String>>,
+    pub files: Vec<MetainfoFile>,
+    pub info_hash: [u8; 20],
+    pub piece_length: u64,
+    pub pieces: Vec<[u8; 20]>,
+}
+
+impl Metainfo {
+    pub fn from_bencode(obj: Object) -> Option<Metainfo> {
+        let metainfo = ts!(obj.as_dict());
+        let info = ts!(metainfo.get_dict("info"));
+
+        let announce = ts!(metainfo.get_string("announce"));
+        let info_hash = sha1(&encode(ts!(metainfo.get_object("info"))));
+        let name = ts!(info.get_str("name"));
+        let piece_length = ts!(info.get_int("piece length"));
+        let pieces = ts!(info.get_bytes("pieces"));
+
+        let mut announce_list = vec![];
+        if let Some(list) = metainfo.get_list("announce-list") {
+            for tier in list.iter() {
+                let mut urls = vec![];
+                for url in ts!(tier.as_list()).iter() {
+                    urls.push(ts!(url.as_string()));
+                }
+                announce_list.push(urls);
+            }
+        }
+
+        let mut files = vec![];
+        if let Some(list) = info.get_list("files") {
+            for obj in list.iter() {
+                let file = ts!(obj.as_dict());
+
+                let mut path = PathBuf::new();
+                path.push(name);
+                for component in ts!(file.get_list("path")).iter() {
+                    path.push(ts!(component.as_str()));
+                }
+
+                files.push(MetainfoFile {
+                    length: ts!(file.get_int("length")) as u64,
+                    path: path,
+                });
+            }
+        } else {
+            let mut path = PathBuf::new();
+            path.push(name);
+
+            files.push(MetainfoFile{
+                length: ts!(info.get_int("length")) as u64,
+                path: path,
+            })
+        }
+
+        Some(Metainfo {
+            announce: announce,
+            announce_list: announce_list,
+            files: files,
+            info_hash: info_hash,
+            piece_length: piece_length as u64,
+            pieces: pieces.chunks(20).map(|c| piece_from_slice(c)).collect::<Vec<_>>(),
+        })
+    }
+}
+
+#[derive(Debug)]
+pub struct MetainfoFile {
+    pub length: u64,
+    pub path: PathBuf,
+}
+
+fn sha1(bytes: &[u8]) -> [u8; 20] {
+    let mut hasher = Sha1::new();
+    hasher.update(bytes);
+    hasher.digest().bytes()
+}
+
+fn piece_from_slice(src: &[u8]) -> [u8; 20] {
+    assert_eq!(src.len(), 20);
+
+    let mut dst = [0u8; 20];
+    dst.copy_from_slice(src);
+    dst
+}
+
+#[cfg(test)]
+mod tests {
+    use std::path::Path;
+
+    use bencode::{Bytes, Dict, List, Object};
+    use metainfo::Metainfo;
+
+    #[test]
+    fn test_single_file() {
+        let mut meta = Dict::new();
+        meta.insert(Bytes::new("announce"), Bytes::wrap("http://ubuntu.com/tracker:6969"));
+
+        let mut info = Dict::new();
+        info.insert(Bytes::new("name"), Bytes::wrap("ubuntu-16.04-desktop.iso"));
+        info.insert(Bytes::new("length"), Object::Int(1024 * 1024 * 1024));
+        info.insert(Bytes::new("piece length"), Object::Int(1024 * 512));
+        info.insert(Bytes::new("pieces"), Bytes::wrap(""));
+
+        meta.insert(Bytes::new("info"), Object::Dict(info));
+
+        let metainfo = Metainfo::from_bencode(Object::Dict(meta)).unwrap();
+        assert_eq!(metainfo.announce, "http://ubuntu.com/tracker:6969");
+        assert_eq!(metainfo.piece_length, 1024 * 512);
+
+        let file = &metainfo.files[0];
+        assert_eq!(file.path.to_str().unwrap(), "ubuntu-16.04-desktop.iso");
+        assert_eq!(file.length, 1024 * 1024 * 1024);
+    }
+
+    #[test]
+    fn test_multiple_files() {
+        let mut meta = Dict::new();
+        meta.insert(Bytes::new("announce"), Bytes::wrap("http://ubuntu.com/tracker:6969"));
+
+        let mut info = Dict::new();
+        info.insert(Bytes::new("name"), Bytes::wrap("base_folder"));
+        info.insert(Bytes::new("piece length"), Object::Int(1024 * 512));
+        info.insert(Bytes::new("pieces"), Bytes::wrap(""));
+
+        let mut files = List::new();
+        let mut file1 = Dict::new();
+        file1.insert(Bytes::new("path"), List::wrap(vec![Bytes::wrap("folder2"), Bytes::wrap("image.txt")]));
+        file1.insert(Bytes::new("length"), Object::Int(512));
+        files.push(Object::Dict(file1));
+        let mut file2 = Dict::new();
+        file2.insert(Bytes::new("path"), List::wrap(vec![Bytes::wrap("txt.jpg")]));
+        file2.insert(Bytes::new("length"), Object::Int(64));
+        files.push(Object::Dict(file2));
+        info.insert(Bytes::new("files"), Object::List(files));
+
+        meta.insert(Bytes::new("info"), Object::Dict(info));
+
+        let metainfo = Metainfo::from_bencode(Object::Dict(meta)).unwrap();
+        assert_eq!(metainfo.announce, "http://ubuntu.com/tracker:6969");
+        assert_eq!(metainfo.piece_length, 1024 * 512);
+
+        let file1 = &metainfo.files[0];
+        assert_eq!(file1.path, Path::new("base_folder/folder2/image.txt"));
+        assert_eq!(file1.length, 512);
+
+        let file2 = &metainfo.files[1];
+        assert_eq!(file2.path, Path::new("base_folder/txt.jpg"));
+        assert_eq!(file2.length, 64);
+    }
+}