chore: initial sanitized public snapshot

2026-07-18 15:24:15 +08:00
commit e489b29e01
321 changed files with 76890 additions and 0 deletions
@@ -0,0 +1,69 @@
+use super::bencode::BencodeValue;
+
+/// Decodes a 40-character hexadecimal string into a fixed-width 20-byte array.
+pub(super) fn decode_hex_20_array(input: &str) -> Result<[u8; 20], String> {
+    if input.len() != 40 {
+        return Err(format!(
+            "expected 40 hex characters for 20-byte info-hash, got {}",
+            input.len()
+        ));
+    }
+    let mut out = [0_u8; 20];
+    for (index, chunk) in input.as_bytes().chunks_exact(2).enumerate() {
+        let hi = decode_hex_nibble(chunk[0])
+            .ok_or_else(|| "info-hash contains non-hex characters".to_owned())?;
+        let lo = decode_hex_nibble(chunk[1])
+            .ok_or_else(|| "info-hash contains non-hex characters".to_owned())?;
+        out[index] = (hi << 4) | lo;
+    }
+    Ok(out)
+}
+
+/// Decodes one ASCII hexadecimal nibble.
+const fn decode_hex_nibble(byte: u8) -> Option<u8> {
+    match byte {
+        b'0'..=b'9' => Some(byte - b'0'),
+        b'a'..=b'f' => Some(byte - b'a' + 10),
+        b'A'..=b'F' => Some(byte - b'A' + 10),
+        _ => None,
+    }
+}
+
+/// Decodes torrent byte strings into owned lossy UTF-8 text.
+pub(super) fn bytes_to_string(bytes: &[u8]) -> String {
+    String::from_utf8_lossy(bytes).into_owned()
+}
+
+/// Converts one torrent bencode value into human-readable string form.
+pub(super) fn value_to_string(value: &BencodeValue) -> String {
+    match value {
+        BencodeValue::Bytes(bytes) => bytes_to_string(bytes),
+        BencodeValue::Int(value) => value.to_string(),
+        BencodeValue::List(values) => values
+            .iter()
+            .map(value_to_string)
+            .collect::<Vec<_>>()
+            .join(","),
+        BencodeValue::Dict(map) => map
+            .iter()
+            .map(|(key, value)| format!("{key}={}", value_to_string(value)))
+            .collect::<Vec<_>>()
+            .join("&"),
+    }
+}
+
+/// Hex-encodes raw torrent bytes using lowercase hexadecimal.
+pub(super) fn hex_encode(bytes: &[u8]) -> String {
+    const HEX: &[u8; 16] = b"0123456789abcdef";
+    let mut out = String::with_capacity(bytes.len() * 2);
+    for &byte in bytes {
+        out.push(char::from(HEX[usize::from(byte >> 4)]));
+        out.push(char::from(HEX[usize::from(byte & 0x0f)]));
+    }
+    out
+}
+
+/// Saturates an integer-like torrent length field into `u64`.
+pub(super) fn i64_to_u64(value: i64) -> u64 {
+    u64::try_from(value.max(0)).unwrap_or(u64::MAX)
+}