feat: include crate version in peer_id

crates/librqbit_core/Cargo.toml

@@ -20,7 +20,7 @@ tokio = { version = "1", features = ["rt-multi-thread", "macros", "time"] }
 hex = "0.4"
 anyhow = "1"
 url = { version = "2", default-features = false }
-uuid = { version = "1", features = ["v4"] }
+rand = "0.8"
 parking_lot = "0.12"
 serde = { version = "1", features = ["derive"] }
 buffers = { path = "../buffers", package = "librqbit-buffers", version = "4.2" }

crates/librqbit_core/src/peer_id.rs

@@ -1,4 +1,18 @@
 use crate::hash_id::Id20;
+use rand::{self, RngCore};
+
+/// Return the version of the invoking crate as a tuple
+#[macro_export]
+macro_rules! crate_version {
+    () => {
+        (
+            env!("CARGO_PKG_VERSION_MAJOR").parse::<u8>().unwrap_or(0),
+            env!("CARGO_PKG_VERSION_MINOR").parse::<u8>().unwrap_or(0),
+            env!("CARGO_PKG_VERSION_PATCH").parse::<u8>().unwrap_or(0),
+            env!("CARGO_PKG_VERSION_PRE").parse::<u8>().unwrap_or(0),
+        )
+    };
+}
 
 #[derive(Debug)]
 pub enum AzureusStyleKind {
@@ -8,13 +22,13 @@ pub enum AzureusStyleKind {
     QBittorrent,
     UTorrent,
     RQBit,
-    Other([char; 2]),
+    Other([u8; 2]),
 }
 
 #[derive(Debug)]
 pub struct AzureusStyle {
     pub kind: AzureusStyleKind,
-    pub version: [char; 4],
+    pub version: [u8; 4],
 }
 
 impl AzureusStyleKind {
@@ -26,7 +40,7 @@ impl AzureusStyleKind {
             b"qB" => AzureusStyleKind::QBittorrent,
             b"UT" => AzureusStyleKind::UTorrent,
             b"rQ" => AzureusStyleKind::RQBit,
-            _ => AzureusStyleKind::Other([b1 as char, b2 as char]),
+            other => AzureusStyleKind::Other(*other),
         }
     }
 }
@@ -36,9 +50,9 @@ fn try_decode_azureus_style(p: &Id20) -> Option<AzureusStyle> {
     if !(p[0] == b'-' && p[7] == b'-') {
         return None;
     }
-    let mut version = ['0'; 4];
+    let mut version = [b'0'; 4];
     for (i, c) in p[3..7].iter().copied().enumerate() {
-        version[i] = c as char;
+        version[i] = version_digit_from_id(c)?;
     }
     let kind = AzureusStyleKind::from_bytes(p[1], p[2]);
     Some(AzureusStyle { kind, version })
@@ -53,13 +67,62 @@ pub fn try_decode_peer_id(p: Id20) -> Option<PeerId> {
     Some(PeerId::AzureusStyle(try_decode_azureus_style(&p)?))
 }
 
-pub fn generate_peer_id() -> Id20 {
+/// Returns `None` for bytes greater than 64
+fn version_digit_to_id(d: u8) -> Option<u8> {
+    let version_map = b"0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz.-";
+    version_map.get(d as usize).copied()
+}
+
+/// Returns `None` for bytes that aren't alphanumeric, `.` or `-`.
+fn version_digit_from_id(d: u8) -> Option<u8> {
+    match d {
+        b'0'..=b'9' => Some(d - b'0'),
+        b'A'..=b'Z' => Some(d - b'0' - 10),
+        b'a'..=b'z' => Some(d - b'0' - 10 - 26),
+        b'.' => Some(62),
+        b'-' => Some(63),
+        _ => None,
+    }
+}
+
+/// Generate a client fingerprint in the Azereus format, where `b"-xx1234-"` corresponds to version `1.2.3.4`` of the torrent client abbreviated by `xx`
+pub fn generate_azereus_style(client: [u8; 2], version: (u8, u8, u8, u8)) -> Id20 {
+    let mut fingerprint = [b'-'; 8];
+
+    fingerprint[1..3].copy_from_slice(&client);
+    fingerprint[3] = version_digit_to_id(version.0).unwrap();
+    fingerprint[4] = version_digit_to_id(version.1).unwrap();
+    fingerprint[5] = version_digit_to_id(version.2).unwrap();
+    fingerprint[6] = version_digit_to_id(version.3).unwrap();
+    generate_peer_id(&fingerprint)
+}
+
+/// Panics if the `fingerprint` slice isn't eight bytes long
+pub fn generate_peer_id(fingerprint: &[u8]) -> Id20 {
     let mut peer_id = [0u8; 20];
 
-    let u = uuid::Uuid::new_v4();
-    peer_id[4..20].copy_from_slice(&u.as_bytes()[..]);
-
-    peer_id[..8].copy_from_slice(b"-rQ7000-");
+    peer_id[..8].copy_from_slice(fingerprint);
+    rand::thread_rng().fill_bytes(&mut peer_id[8..]);
 
     Id20::new(peer_id)
 }
+
+#[cfg(test)]
+mod tests {
+    use crate::peer_id::generate_azereus_style;
+
+    #[test]
+    fn test_azereus_peer_id_generation() {
+        for (client, version, correct_fingerprint) in [
+            (*b"xx", (1, 2, 3, 4), *b"-xx1234-"),
+            (*b"00", (10, 0, 0, 0), *b"-00A000-"),
+            (*b"\xFF\xFF", (36, 37, 62, 63), *b"-\xFF\xFFab.--"),
+        ] {
+            let id1 = generate_azereus_style(client, version);
+            let id2 = generate_azereus_style(client, version);
+            assert_ne!(id1, id2);
+            assert_eq!(id1.0[..8], id2.0[..8]);
+            assert_eq!(id1.0[..8], correct_fingerprint);
+        }
+    }
+}