Initial

.gitignore

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+target/

Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "messages"
+version = "0.1.0"

README.md

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+# sans-gres
+A sans-io based implementation of the postgres protocol

cargo.toml

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+[workspace]
+members = ["messages"]
+resolver = "3"

messages/.gitignore

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+/target

messages/Cargo.toml

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+[package]
+name = "messages"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]

messages/src/datatypes.rs

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+//! [Postgres Docs](https://www.postgresql.org/docs/current/protocol-message-types.html#PROTOCOL-MESSAGE-TYPES)
+
+#[derive(Debug)]
+pub enum DataTypeError {
+    Other(&'static str),
+}
+
+pub trait DataType: Sized {
+    fn parse<'b1, 'b2>(buffer: &'b1 [u8]) -> Result<(Self, &'b2 [u8]), DataTypeError> where 'b1: 'b2;
+
+    fn encoding_length(&self) -> usize;
+    fn encode<W>(&self, writer: &mut W) where W: std::io::Write;
+}
+
+impl DataType for i32 {
+    fn parse<'b1, 'b2>(buffer: &'b1 [u8]) -> Result<(Self, &'b2 [u8]), DataTypeError> where 'b1: 'b2 {
+        let relevant_data = &buffer[0..4];
+        let value = i32::from_be_bytes(relevant_data.try_into().unwrap());
+
+        Ok((value, &buffer[4..]))
+    }
+
+    fn encoding_length(&self) -> usize {
+        4
+    }
+
+    fn encode<W>(&self, writer: &mut W) where W: std::io::Write {
+        let content = self.to_be_bytes();
+        writer.write_all(&content).unwrap();
+    }
+}
+
+impl DataType for String {
+    fn parse<'b1, 'b2>(buffer: &'b1 [u8]) -> Result<(Self, &'b2 [u8]), DataTypeError> where 'b1: 'b2 {
+        let str_length = buffer.iter().enumerate().find(|(_, v)| **v == 0).map(|(i, _)| i).unwrap();
+        let raw_content = &buffer[0..str_length];
+        let content = str::from_utf8(raw_content).unwrap();
+
+        Ok((content.to_owned(), &buffer[str_length+1..]))
+    }
+
+    fn encoding_length(&self) -> usize {
+        self.len() + 1
+    }
+
+    fn encode<W>(&self, writer: &mut W) where W: std::io::Write {
+        writer.write_all(self.as_bytes()).unwrap();
+        writer.write_all(&[0]).unwrap();
+    }
+}

messages/src/lib.rs

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+pub mod startup;
+pub mod datatypes;
+
+#[derive(Debug)]
+pub enum MessageParseError {
+    MismatchedId {
+        expected: u8,
+        found: u8,
+    },
+    Other(&'static str),
+}
+
+#[derive(Debug)]
+pub enum EncodeError {
+    IO(std::io::Error),
+    Other(&'static str),
+}
+
+pub trait Message: Sized {
+    const ID: Option<u8>;
+
+    fn parse<'b1, 'b2>(buffer: &'b1 [u8]) -> Result<(Self, &'b2 [u8]), MessageParseError> where 'b1: 'b2;
+
+    fn encode<W>(&self, writer: &mut W) -> Result<(), EncodeError> where W: std::io::Write;
+}
+
+impl From<std::io::Error> for EncodeError {
+    fn from(value: std::io::Error) -> Self {
+        Self::IO(value)
+    }
+}

messages/src/startup.rs

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+use crate::{EncodeError, Message, MessageParseError, datatypes::DataType};
+
+/// Sent by the Frontend
+///
+/// [Postgres Docs](https://www.postgresql.org/docs/current/protocol-message-formats.html#PROTOCOL-MESSAGE-FORMATS-SSLREQUEST)
+#[derive(Debug, PartialEq)]
+pub struct SSLRequest {}
+
+impl Message for SSLRequest {
+    const ID: Option<u8> = None;
+
+    fn parse<'b1, 'b2>(buffer: &'b1 [u8]) -> Result<(Self, &'b2 [u8]), MessageParseError> where 'b1: 'b2 {
+        let (length, _) = i32::parse(buffer).unwrap();
+        let (code, _) = i32::parse(&buffer[4..8]).unwrap();
+
+        if length != 8 || code != 80877103 {
+            return Err(MessageParseError::Other("Not an SSLRequest"));
+        }
+
+        Ok((Self {}, &buffer[8..]))
+    }
+
+    fn encode<W>(&self, writer: &mut W) -> Result<(), EncodeError> where W: std::io::Write {
+        8i32.encode(writer);
+        80877103i32.encode(writer);
+        Ok(())
+    }
+}
+
+/// Sent by the Backend
+#[derive(Debug, PartialEq)]
+pub struct SSLResponse {
+    pub enabled: bool,
+}
+
+impl Message for SSLResponse {
+    const ID: Option<u8> = None;
+
+    fn parse<'b1, 'b2>(buffer: &'b1 [u8]) -> Result<(Self, &'b2 [u8]), MessageParseError> where 'b1: 'b2 {
+        let flag = buffer[0];
+
+        if flag != b'S' && flag != b'N' {
+            return Err(MessageParseError::Other("Invalid value for SSL Response"));
+        }
+
+        Ok((Self {
+            enabled: flag == b'S',
+        }, &buffer[1..]))
+    }
+
+    fn encode<W>(&self, writer: &mut W) -> Result<(), EncodeError> where W: std::io::Write {
+        let flag = if self.enabled { b'S' } else { b'N' };
+        writer.write_all(&[flag])?;
+        Ok(())
+    }
+}
+
+/// Sent by the frontend
+///
+/// [Postgres Docs](https://www.postgresql.org/docs/current/protocol-message-formats.html#PROTOCOL-MESSAGE-FORMATS-STARTUPMESSAGE)
+#[derive(Debug, PartialEq)]
+pub struct Startup {
+    pub version: i32,
+    pub parameters: Vec<(String, String)>,
+}
+
+impl Message for Startup {
+    const ID: Option<u8> = None;
+
+    fn parse<'b1, 'b2>(in_buffer: &'b1 [u8]) -> Result<(Self, &'b2 [u8]), crate::MessageParseError> where 'b1: 'b2 {
+        let (length, _) = i32::parse(in_buffer).unwrap();
+
+        let buffer = &in_buffer[4..length as usize];
+        
+        let (version, buffer) = i32::parse(buffer).unwrap();
+        
+        let mut parameters = Vec::new();
+
+        let mut buffer = buffer;
+        while buffer.first().is_some_and(|v| *v != 0) {
+            let (name, tmp_buffer) = String::parse(buffer).unwrap();
+            let (value, tmp_buffer) = String::parse(tmp_buffer).unwrap();
+
+            parameters.push((name, value));
+
+            buffer = tmp_buffer;
+        }
+
+        if !buffer.first().is_some_and(|v| *v == 0) {
+            return Err(MessageParseError::Other("TODO"));
+        }
+
+        Ok((Self {
+            version,
+            parameters,
+        }, &in_buffer[length as usize..]))
+    }
+
+    fn encode<W>(&self, writer: &mut W) -> Result<(), EncodeError> where W: std::io::Write {
+        let version_length = self.version.encoding_length();
+        let parameters_length = self.parameters.iter().map(|(k, v)| k.encoding_length() + v.encoding_length()).sum::<usize>()+1;
+
+        ((4+version_length+parameters_length) as i32).encode(writer);
+        self.version.encode(writer);
+        for (k, v) in self.parameters.iter() {
+            k.encode(writer);
+            v.encode(writer);
+        }
+        writer.write_all(&[0])?;
+        Ok(())
+    }
+}
+
+/// Sent by the backend
+///
+/// [Postgres Docs](https://www.postgresql.org/docs/current/protocol-message-formats.html#PROTOCOL-MESSAGE-FORMATS-AUTHENTICATIONOK)
+#[derive(Debug, PartialEq)]
+pub struct AuthenticationOk {}
+
+impl Message for AuthenticationOk {
+    const ID: Option<u8> = Some(b'R');
+
+    fn parse<'b1, 'b2>(buffer: &'b1 [u8]) -> Result<(Self, &'b2 [u8]), MessageParseError> where 'b1: 'b2 {
+        let id = buffer[0];
+        if id != Self::ID.unwrap() {
+            return Err(MessageParseError::MismatchedId { expected: Self::ID.unwrap(), found: id });
+        }
+
+        let (len, buffer) = i32::parse(&buffer[1..]).unwrap();
+        if len != 8 {
+            return Err(MessageParseError::Other("Expected a length of 8"));
+        }
+
+        let (code, buffer) = i32::parse(buffer).unwrap();
+        if code != 0 {
+            return Err(MessageParseError::Other("Expectede the code to be 0"));
+        }
+
+        Ok((Self {}, buffer))
+    }
+
+    fn encode<W>(&self, writer: &mut W) -> Result<(), EncodeError> where W: std::io::Write {
+        writer.write_all(&[Self::ID.unwrap()])?;
+        8i32.encode(writer);
+        0i32.encode(writer);
+        Ok(())
+    }
+}
+
+/// Sent by the backend
+///
+/// [Postgres Docs](https://www.postgresql.org/docs/current/protocol-message-formats.html#PROTOCOL-MESSAGE-FORMATS-PARAMETERSTATUS)
+#[derive(Debug, PartialEq)]
+pub struct ParameterStatus {
+    pub name: String,
+    pub value: String,
+}
+
+impl Message for ParameterStatus {
+    const ID: Option<u8> = Some(b'S');
+
+    fn parse<'b1, 'b2>(buffer: &'b1 [u8]) -> Result<(Self, &'b2 [u8]), MessageParseError> where 'b1: 'b2 {
+        let id = buffer[0];
+        if id != Self::ID.unwrap() {
+            return Err(MessageParseError::MismatchedId { expected: Self::ID.unwrap(), found: id });
+        }
+
+        let (len, buffer) = i32::parse(&buffer[1..]).unwrap();
+
+        let (name, buffer) = String::parse(buffer).unwrap();
+        let (value, buffer) = String::parse(buffer).unwrap();
+
+        Ok((Self { name, value }, buffer))
+    }
+
+    fn encode<W>(&self, writer: &mut W) -> Result<(), EncodeError> where W: std::io::Write {
+        let name_length = self.name.encoding_length();
+        let value_length = self.value.encoding_length();
+
+        writer.write_all(&[Self::ID.unwrap()])?;
+        ((4+name_length+value_length) as i32).encode(writer);
+        self.name.encode(writer);
+        self.value.encode(writer);
+        Ok(())
+    }
+}
+
+/// Sent by the backend
+///
+/// [Postgres Docs](https://www.postgresql.org/docs/current/protocol-message-formats.html#PROTOCOL-MESSAGE-FORMATS-BACKENDKEYDATA)
+#[derive(Debug, PartialEq)]
+pub struct BackendKeyData {
+    pub process_id: i32,
+    pub secret_key: Vec<u8>,
+}
+
+impl Message for BackendKeyData {
+    const ID: Option<u8> = Some(b'K');
+
+    fn parse<'b1, 'b2>(buffer: &'b1 [u8]) -> Result<(Self, &'b2 [u8]), MessageParseError> where 'b1: 'b2 {
+        let id = buffer[0];
+        if id != Self::ID.unwrap() {
+            return Err(MessageParseError::MismatchedId { expected: Self::ID.unwrap(), found: id });
+        }
+
+        let (len, buffer) = i32::parse(&buffer[1..]).unwrap();
+
+        let inner_buffer = &buffer[..len as usize - 4];
+
+        let (process_id, inner_buffer) = i32::parse(inner_buffer).unwrap();
+
+        Ok((Self {
+            process_id,
+            secret_key: inner_buffer.to_vec(),
+        }, &buffer[len as usize - 4..]))
+    }
+
+    fn encode<W>(&self, writer: &mut W) -> Result<(), EncodeError> where W: std::io::Write {
+        let process_len = self.process_id.encoding_length();
+        let secret_key_length = self.secret_key.len();
+
+        writer.write_all(&[Self::ID.unwrap()])?;
+        ((4+process_len+secret_key_length) as i32).encode(writer);
+        self.process_id.encode(writer);
+        writer.write_all(self.secret_key.as_slice())?;
+
+        Ok(())
+    }
+}

messages/tests/startup.rs

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+use messages::{Message, startup::{AuthenticationOk, BackendKeyData, ParameterStatus, SSLRequest, SSLResponse, Startup}};
+
+#[test]
+fn collected_startup() {
+    let raw_bytes: &[u8] = &[0x0, 0x0, 0x0, 0x3f, 0x0, 0x3, 0x0, 0x0, 0x75, 0x73, 0x65, 0x72, 0x0, 0x70, 0x6f, 0x73, 0x74, 0x67, 0x72, 0x65, 0x73, 0x0, 0x64, 0x61, 0x74, 0x61, 0x62, 0x61, 0x73, 0x65, 0x0, 0x70, 0x6f, 0x73, 0x74, 0x67, 0x72, 0x65, 0x73, 0x0, 0x61, 0x70, 0x70, 0x6c, 0x69, 0x63, 0x61, 0x74, 0x69, 0x6f, 0x6e, 0x5f, 0x6e, 0x61, 0x6d, 0x65, 0x0, 0x70, 0x73, 0x71, 0x6c, 0x0, 0x0];
+
+    let (parsed, rem) = Startup::parse(raw_bytes).unwrap();
+
+    assert_eq!(&[] as &[u8], rem);
+    assert_eq!(Startup {
+        version: 196608,
+        parameters: vec![
+            ("user".into(), "postgres".into()),
+            ("database".into(), "postgres".into()),
+            ("application_name".into(), "psql".into()),
+        ],
+    }, parsed);
+
+    let mut output = Vec::<u8>::new();
+    parsed.encode(&mut output);
+    assert_eq!(raw_bytes, output.as_slice());
+}
+
+#[test]
+fn collected_sslrequest() {
+    let raw_bytes: &[u8] = &[0x0, 0x0, 0x0, 0x8, 0x4, 0xd2, 0x16, 0x2f];
+
+    let (parsed, rem) = SSLRequest::parse(raw_bytes).unwrap();
+
+    assert_eq!(&[] as &[u8], rem);
+    assert_eq!(SSLRequest {}, parsed);
+
+    let mut output = Vec::<u8>::new();
+    parsed.encode(&mut output);
+    assert_eq!(raw_bytes, output.as_slice());
+}
+
+#[test]
+fn collected_sslresponse() {
+    let raw_bytes: &[u8] = &[0x4e];
+
+    let (parsed, rem) = SSLResponse::parse(raw_bytes).unwrap();
+
+    assert_eq!(&[] as &[u8], rem);
+    assert_eq!(SSLResponse {
+        enabled: false,
+    }, parsed);
+
+    let mut output = Vec::<u8>::new();
+    parsed.encode(&mut output);
+    assert_eq!(raw_bytes, output.as_slice());
+}
+
+#[test]
+fn collected_authenticationok() {
+    let raw_bytes: &[u8] = &[0x52, 0x0, 0x0, 0x0, 0x8, 0x0, 0x0, 0x0, 0x0];
+
+    let (parsed, rem) = AuthenticationOk::parse(raw_bytes).unwrap();
+
+    assert_eq!(&[] as &[u8], rem);
+    assert_eq!(AuthenticationOk {}, parsed);
+
+    let mut output = Vec::<u8>::new();
+    parsed.encode(&mut output);
+    assert_eq!(raw_bytes, output.as_slice());
+}
+
+#[test]
+fn collected_parameterstatus() {
+    let raw_bytes: &[u8] = &[0x53, 0x0, 0x0, 0x0, 0x17, 0x69, 0x6e, 0x5f, 0x68, 0x6f, 0x74, 0x5f, 0x73, 0x74, 0x61, 0x6e, 0x64, 0x62, 0x79, 0x0, 0x6f, 0x66, 0x66, 0x0];
+
+    let (parsed, rem) = ParameterStatus::parse(raw_bytes).unwrap();
+
+    assert_eq!(&[] as &[u8], rem);
+    assert_eq!(ParameterStatus {
+        name: "in_hot_standby".into(),
+        value: "off".into(),
+    }, parsed);
+
+    let mut output = Vec::<u8>::new();
+    parsed.encode(&mut output);
+    assert_eq!(raw_bytes, output.as_slice());
+}
+
+#[test]
+fn collected_backendkeydata() {
+    let raw_bytes: &[u8] = &[0x4b, 0x0, 0x0, 0x0, 0xc, 0x0, 0x0, 0x0, 0x4b, 0x72, 0xb, 0xd3, 0xd6];
+
+    let (parsed, rem) = BackendKeyData::parse(raw_bytes).unwrap();
+
+    assert_eq!(&[] as &[u8], rem);
+    assert_eq!(BackendKeyData {
+        process_id: 75,
+        secret_key: vec![0x72, 0x0b, 0xd3, 0xd6],
+    }, parsed);
+
+    let mut output = Vec::<u8>::new();
+    parsed.encode(&mut output);
+    assert_eq!(raw_bytes, output.as_slice());
+}

traces/README.md

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+# Traces

traces/trace.sh

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+#!/bin/bash
+
+set -xe
+
+DB_CONTAINER_ID=$(docker run -d -e POSTGRES_PASSWORD=test postgres:18)
+
+echo $DB_CONTAINER_ID
+
+mkdir -p output/
+
+TRACE_CONTAINER_ID=$(docker run --rm \
+  --network container:$DB_CONTAINER_ID \
+  --cap-add NET_RAW \
+  --cap-add NET_ADMIN \
+  -v "$PWD/output:/captures" \
+  -d \
+  nicolaka/netshoot \
+  tcpdump -i lo -nn -U -w /captures/container.pcap)
+
+sleep 3
+
+echo "SELECT 1;" | docker run --rm --network container:$DB_CONTAINER_ID -i postgres:18 psql -h localhost -p 5432 -U postgres;
+
+sleep 3
+
+docker stop $TRACE_CONTAINER_ID
+docker stop $DB_CONTAINER_ID