feat: initial utils for reading/writing e2s files

portal-bridge/src/types/e2s.rs

@@ -0,0 +1,190 @@
+use anyhow::anyhow;
+use ssz_derive::{Decode, Encode};
+
+const _SLOTS_PER_HISTORICAL_ROOT: usize = 8192;
+const HEADER_SIZE: u16 = 8;
+const VALUE_SIZE_LIMIT: usize = 1024 * 1024 * 50; // 50 MB
+
+struct File {
+    entries: Vec<Entry>,
+}
+
+#[allow(dead_code)]
+impl File {
+    fn encode(&self) -> anyhow::Result<Vec<u8>> {
+        let length = self.entries.iter().map(|e| e.length() as u32).sum::<u32>() as usize;
+        let mut buf = vec![0; length];
+        self.write(&mut buf)?;
+        Ok(buf)
+    }
+
+    fn write(&self, buf: &mut [u8]) -> anyhow::Result<()> {
+        let mut offset = 0;
+        for entry in &self.entries {
+            let entry_length = entry.length();
+            entry.write(&mut buf[offset..offset + entry_length])?;
+            offset += entry_length;
+        }
+        Ok(())
+    }
+
+    fn read(buf: &[u8]) -> anyhow::Result<Self> {
+        let mut entries = Vec::new();
+        let mut offset = 0;
+        while offset < buf.len() {
+            let entry_length = u32::from_le_bytes([
+                buf[offset + 2],
+                buf[offset + 3],
+                buf[offset + 4],
+                buf[offset + 5],
+            ]) + HEADER_SIZE as u32;
+            let terminating_entry_index = offset + entry_length as usize;
+            if buf.len() < terminating_entry_index {
+                return Err(anyhow!(
+                    "invalid buf length: {} - expected {}",
+                    buf.len(),
+                    terminating_entry_index
+                ));
+            }
+            let entry = Entry::read(&buf[offset..terminating_entry_index])?;
+            offset += entry_length as usize;
+            entries.push(entry);
+        }
+        Ok(Self { entries })
+    }
+}
+
+struct Entry {
+    header: Header,
+    value: Vec<u8>,
+}
+
+#[allow(dead_code)]
+impl Entry {
+    fn length(&self) -> usize {
+        HEADER_SIZE as usize + self.header.length as usize
+    }
+
+    fn encode(&self) -> anyhow::Result<Vec<u8>> {
+        let length = self.length();
+        let mut buf = vec![0; length];
+        self.write(&mut buf)?;
+        Ok(buf)
+    }
+
+    fn write(&self, buf: &mut [u8]) -> anyhow::Result<()> {
+        if self.length() != buf.len() {
+            return Err(anyhow!(
+                "found invalid buf length for entry: {} - expected {}",
+                buf.len(),
+                self.length()
+            ));
+        }
+        if self.length() > VALUE_SIZE_LIMIT {
+            return Err(anyhow!(
+                "entry value size limit exceeded: {} - {}",
+                self.length(),
+                VALUE_SIZE_LIMIT
+            ));
+        }
+        self.header.write(buf);
+        buf[8..].copy_from_slice(&self.value);
+        Ok(())
+    }
+
+    fn read(buf: &[u8]) -> anyhow::Result<Self> {
+        Ok(Self {
+            header: Header::read(&buf[0..8])?,
+            value: buf[8..].to_vec(),
+        })
+    }
+}
+
+#[derive(Decode, Encode)]
+struct Header {
+    entry_type: u16,
+    length: u32,
+    reserved: u16,
+}
+
+impl Header {
+    fn write(&self, buf: &mut [u8]) {
+        buf[0..2].copy_from_slice(&self.entry_type.to_le_bytes());
+        buf[2..6].copy_from_slice(&self.length.to_le_bytes());
+        buf[6..8].copy_from_slice(&self.reserved.to_le_bytes());
+    }
+
+    fn read(buf: &[u8]) -> anyhow::Result<Self> {
+        if buf.len() != HEADER_SIZE as usize {
+            return Err(anyhow!("invalid header size: {}", buf.len()));
+        }
+        let entry_type = u16::from_le_bytes([buf[0], buf[1]]);
+        let length = u32::from_le_bytes([buf[2], buf[3], buf[4], buf[5]]);
+        let reserved = u16::from_le_bytes([buf[6], buf[7]]);
+        if reserved != 0 {
+            return Err(anyhow!("invalid reserved value: {} - expected 0", reserved));
+        }
+        Ok(Self {
+            entry_type,
+            length,
+            reserved,
+        })
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+    use ethportal_api::utils::bytes::{hex_decode, hex_encode};
+
+    // test cases sourced from: https://github.com/ethereum/go-ethereum/pull/26621/
+
+    #[test]
+    fn test_entry_empty() {
+        let expected = "0xffff000000000000";
+        let entry = Entry::read(&hex_decode(expected).unwrap()).unwrap();
+        assert_eq!(entry.header.entry_type, 0xffff);
+        assert_eq!(entry.header.length, 0);
+        assert_eq!(entry.header.reserved, 0);
+        assert_eq!(entry.value.len(), 0);
+        let actual = entry.encode().unwrap();
+        assert_eq!(hex_encode(actual), expected);
+    }
+
+    #[test]
+    fn test_entry_beef() {
+        let expected = "0x2a00020000000000beef";
+        let entry = Entry::read(&hex_decode(expected).unwrap()).unwrap();
+        assert_eq!(entry.header.entry_type, 0x2a); // 42
+        assert_eq!(entry.header.length, 2);
+        assert_eq!(entry.header.reserved, 0);
+        assert_eq!(entry.value, vec![0xbe, 0xef]);
+        let actual = entry.encode().unwrap();
+        assert_eq!(hex_encode(actual), expected);
+    }
+
+    #[test]
+    fn test_entry_multiple() {
+        let expected = "0x2a00020000000000beef0900040000000000abcdabcd";
+        let file = File::read(&hex_decode(expected).unwrap()).unwrap();
+        assert_eq!(file.entries.len(), 2);
+        assert_eq!(file.entries[0].header.entry_type, 0x2a); // 42
+        assert_eq!(file.entries[0].header.length, 2);
+        assert_eq!(file.entries[0].header.reserved, 0);
+        assert_eq!(file.entries[0].value, vec![0xbe, 0xef]);
+        assert_eq!(file.entries[1].header.entry_type, 0x09); // 9
+        assert_eq!(file.entries[1].header.length, 4);
+        assert_eq!(file.entries[1].header.reserved, 0);
+        assert_eq!(file.entries[1].value, vec![0xab, 0xcd, 0xab, 0xcd]);
+        let actual = file.encode().unwrap();
+        assert_eq!(hex_encode(actual), expected);
+    }
+
+    #[rstest::rstest]
+    #[case("0xffff000000000001")] // reserved bytes are non-zero
+    #[case("0xbeef010000000000")] // length exceeds buffer
+    fn test_entry_invalid_decoding(#[case] input: &str) {
+        let buf = hex_decode(input).unwrap();
+        assert!(File::read(&buf).is_err());
+    }
+}

portal-bridge/src/types/mod.rs

@@ -1,3 +1,4 @@
+pub mod e2s;
 pub mod full_header;
 pub mod mode;
 pub mod network;