add git http handling

4 files changed, 730 insertions, 0 deletions

diff --git a/src/git/handlers.rs b/src/git/handlers.rs
new file mode 100644
index 0000000..0efc9d0
--- /dev/null
+++ b/src/git/handlers.rs
@@ -0,0 +1,209 @@
+//! Git HTTP Protocol Handlers
+//!
+//! This module implements the HTTP handlers for Git Smart HTTP protocol.
+
+use std::path::PathBuf;
+use hyper::{body::Bytes, Response, StatusCode};
+use tokio::io::{AsyncReadExt, AsyncWriteExt};
+use tracing::{debug, error, warn};
+
+use super::protocol::{GitService, PktLine};
+use super::subprocess::GitSubprocess;
+
+/// Handle GET /info/refs?service=git-{upload,receive}-pack
+///
+/// This advertises the repository's refs to the client.
+pub async fn handle_info_refs(
+    repo_path: PathBuf,
+    service: GitService,
+) -> Result<Response<String>, GitError> {
+    debug!("Handling info/refs for {:?} with service {:?}", repo_path, service);
+
+    // Check if repository exists
+    if !repo_path.exists() {
+        warn!("Repository not found: {:?}", repo_path);
+        return Err(GitError::RepositoryNotFound);
+    }
+
+    // Spawn git with --advertise-refs
+    let mut git = GitSubprocess::spawn(service, &repo_path, true)
+        .map_err(|e| {
+            error!("Failed to spawn git process: {}", e);
+            GitError::ProcessSpawnFailed(e)
+        })?;
+
+    // Read the output from git
+    let mut output = Vec::new();
+    if let Some(stdout) = git.take_stdout() {
+        let mut stdout = stdout;
+        stdout.read_to_end(&mut output).await
+            .map_err(|e| {
+                error!("Failed to read git output: {}", e);
+                GitError::IoError(e)
+            })?;
+    }
+
+    // Wait for process to complete
+    let status = git.wait().await
+        .map_err(|e| {
+            error!("Failed to wait for git process: {}", e);
+            GitError::IoError(e)
+        })?;
+
+    if !status.success() {
+        error!("Git process failed with status: {:?}", status);
+        return Err(GitError::GitFailed(status.code()));
+    }
+
+    // Build response with pkt-line header
+    let mut response_body = Vec::new();
+    
+    // First line: service advertisement
+    let service_line = format!("# service={}\n", service.as_str());
+    response_body.extend_from_slice(&PktLine::data(service_line.as_bytes()).encode());
+    response_body.extend_from_slice(&PktLine::flush().encode());
+    
+    // Then the git output
+    response_body.extend_from_slice(&output);
+
+    Ok(Response::builder()
+        .status(StatusCode::OK)
+        .header("content-type", service.advertisement_content_type())
+        .header("cache-control", "no-cache")
+        .body(String::from_utf8_lossy(&response_body).to_string())
+        .unwrap())
+}
+
+/// Handle POST /git-upload-pack (clone/fetch)
+pub async fn handle_upload_pack(
+    repo_path: PathBuf,
+    request_body: Bytes,
+) -> Result<Response<String>, GitError> {
+    debug!("Handling upload-pack for {:?}", repo_path);
+
+    if !repo_path.exists() {
+        return Err(GitError::RepositoryNotFound);
+    }
+
+    // Spawn git upload-pack
+    let mut git = GitSubprocess::spawn(GitService::UploadPack, &repo_path, false)
+        .map_err(GitError::ProcessSpawnFailed)?;
+
+    // Write request to git's stdin
+    if let Some(mut stdin) = git.take_stdin() {
+        stdin.write_all(&request_body).await
+            .map_err(GitError::IoError)?;
+        // Close stdin to signal end of input
+        drop(stdin);
+    }
+
+    // Read response from git's stdout
+    let mut output = Vec::new();
+    if let Some(stdout) = git.take_stdout() {
+        let mut stdout = stdout;
+        stdout.read_to_end(&mut output).await
+            .map_err(GitError::IoError)?;
+    }
+
+    // Wait for process
+    let status = git.wait().await
+        .map_err(GitError::IoError)?;
+
+    if !status.success() {
+        return Err(GitError::GitFailed(status.code()));
+    }
+
+    Ok(Response::builder()
+        .status(StatusCode::OK)
+        .header("content-type", GitService::UploadPack.result_content_type())
+        .header("cache-control", "no-cache")
+        .body(String::from_utf8_lossy(&output).to_string())
+        .unwrap())
+}
+
+/// Handle POST /git-receive-pack (push)
+///
+/// This includes an authorization hook point where GRASP validation will be added.
+pub async fn handle_receive_pack(
+    repo_path: PathBuf,
+    request_body: Bytes,
+) -> Result<Response<String>, GitError> {
+    debug!("Handling receive-pack for {:?}", repo_path);
+
+    if !repo_path.exists() {
+        return Err(GitError::RepositoryNotFound);
+    }
+
+    // TODO: Add GRASP authorization here
+    // For now, we'll accept all pushes to enable testing
+    debug!("Authorization check would go here (currently accepting all pushes)");
+
+    // Spawn git receive-pack
+    let mut git = GitSubprocess::spawn(GitService::ReceivePack, &repo_path, false)
+        .map_err(GitError::ProcessSpawnFailed)?;
+
+    // Write request to git's stdin
+    if let Some(mut stdin) = git.take_stdin() {
+        stdin.write_all(&request_body).await
+            .map_err(GitError::IoError)?;
+        drop(stdin);
+    }
+
+    // Read response from git's stdout
+    let mut output = Vec::new();
+    if let Some(stdout) = git.take_stdout() {
+        let mut stdout = stdout;
+        stdout.read_to_end(&mut output).await
+            .map_err(GitError::IoError)?;
+    }
+
+    // Wait for process
+    let status = git.wait().await
+        .map_err(GitError::IoError)?;
+
+    if !status.success() {
+        return Err(GitError::GitFailed(status.code()));
+    }
+
+    Ok(Response::builder()
+        .status(StatusCode::OK)
+        .header("content-type", GitService::ReceivePack.result_content_type())
+        .header("cache-control", "no-cache")
+        .body(String::from_utf8_lossy(&output).to_string())
+        .unwrap())
+}
+
+/// Errors that can occur in Git handlers
+#[derive(Debug)]
+pub enum GitError {
+    RepositoryNotFound,
+    ProcessSpawnFailed(std::io::Error),
+    IoError(std::io::Error),
+    GitFailed(Option<i32>),
+    Unauthorized,
+}
+
+impl std::fmt::Display for GitError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Self::RepositoryNotFound => write!(f, "repository not found"),
+            Self::ProcessSpawnFailed(e) => write!(f, "failed to spawn git process: {}", e),
+            Self::IoError(e) => write!(f, "IO error: {}", e),
+            Self::GitFailed(code) => write!(f, "git process failed with code: {:?}", code),
+            Self::Unauthorized => write!(f, "unauthorized"),
+        }
+    }
+}
+
+impl std::error::Error for GitError {}
+
+impl GitError {
+    /// Convert to HTTP status code
+    pub fn status_code(&self) -> StatusCode {
+        match self {
+            Self::RepositoryNotFound => StatusCode::NOT_FOUND,
+            Self::Unauthorized => StatusCode::FORBIDDEN,
+            _ => StatusCode::INTERNAL_SERVER_ERROR,
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/git/mod.rs b/src/git/mod.rs
new file mode 100644
index 0000000..bd3b9e8
--- /dev/null
+++ b/src/git/mod.rs
@@ -0,0 +1,127 @@
+//! Git Smart HTTP Backend
+//!
+//! This module implements Git Smart HTTP protocol support for ngit-grasp.
+//! It provides handlers for clone, fetch, and push operations over HTTP.
+//!
+//! # Architecture
+//!
+//! - `protocol` - Git pkt-line format parsing and utilities
+//! - `subprocess` - Git process spawning and management
+//! - `handlers` - HTTP request handlers for Git operations
+//!
+//! # URL Patterns
+//!
+//! The following URL patterns are supported:
+//! - `GET /<npub>/<identifier>.git/info/refs?service=git-upload-pack` - Clone/fetch advertisement
+//! - `GET /<npub>/<identifier>.git/info/refs?service=git-receive-pack` - Push advertisement
+//! - `POST /<npub>/<identifier>.git/git-upload-pack` - Clone/fetch operation
+//! - `POST /<npub>/<identifier>.git/git-receive-pack` - Push operation
+
+pub mod handlers;
+pub mod protocol;
+pub mod subprocess;
+
+use std::path::PathBuf;
+
+/// Parse a Git repository path from URL components
+///
+/// Converts /<npub>/<identifier>.git/* to a filesystem path
+///
+/// # Arguments
+/// * `git_data_path` - Base directory for Git repositories
+/// * `npub` - The npub (Nostr public key in bech32 format)
+/// * `identifier` - The repository identifier
+///
+/// # Returns
+/// Path to the bare Git repository
+pub fn resolve_repo_path(git_data_path: &str, npub: &str, identifier: &str) -> PathBuf {
+    // Remove .git suffix if present
+    let identifier = identifier.strip_suffix(".git").unwrap_or(identifier);
+    
+    PathBuf::from(git_data_path)
+        .join(npub)
+        .join(format!("{}.git", identifier))
+}
+
+/// Extract npub and identifier from a Git URL path
+///
+/// Parses paths like `/<npub>/<identifier>.git/info/refs`
+///
+/// Returns (npub, identifier, subpath) where subpath is the part after .git/
+pub fn parse_git_url(path: &str) -> Option<(&str, &str, &str)> {
+    // Remove leading slash
+    let path = path.strip_prefix('/').unwrap_or(path);
+    
+    // Split into components
+    let parts: Vec<&str> = path.splitn(3, '/').collect();
+    
+    if parts.len() < 3 {
+        return None;
+    }
+    
+    let npub = parts[0];
+    let repo_part = parts[1];
+    let subpath = parts[2];
+    
+    // Extract identifier (remove .git suffix if present for the middle part)
+    let identifier = if repo_part.ends_with(".git") {
+        &repo_part[..repo_part.len() - 4]
+    } else {
+        repo_part
+    };
+    
+    Some((npub, identifier, subpath))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_resolve_repo_path() {
+        let path = resolve_repo_path(
+            "/data/git",
+            "npub1abc123",
+            "my-repo"
+        );
+        assert_eq!(
+            path,
+            PathBuf::from("/data/git/npub1abc123/my-repo.git")
+        );
+    }
+
+    #[test]
+    fn test_resolve_repo_path_with_git_suffix() {
+        let path = resolve_repo_path(
+            "/data/git",
+            "npub1abc123",
+            "my-repo.git"
+        );
+        assert_eq!(
+            path,
+            PathBuf::from("/data/git/npub1abc123/my-repo.git")
+        );
+    }
+
+    #[test]
+    fn test_parse_git_url_info_refs() {
+        let (npub, id, subpath) = parse_git_url("/npub1abc/repo.git/info/refs").unwrap();
+        assert_eq!(npub, "npub1abc");
+        assert_eq!(id, "repo");
+        assert_eq!(subpath, "info/refs");
+    }
+
+    #[test]
+    fn test_parse_git_url_upload_pack() {
+        let (npub, id, subpath) = parse_git_url("/npub1abc/repo.git/git-upload-pack").unwrap();
+        assert_eq!(npub, "npub1abc");
+        assert_eq!(id, "repo");
+        assert_eq!(subpath, "git-upload-pack");
+    }
+
+    #[test]
+    fn test_parse_git_url_invalid() {
+        assert!(parse_git_url("/npub1abc").is_none());
+        assert!(parse_git_url("/npub1abc/repo").is_none());
+    }
+}
\ No newline at end of file
diff --git a/src/git/protocol.rs b/src/git/protocol.rs
new file mode 100644
index 0000000..84da131
--- /dev/null
+++ b/src/git/protocol.rs
@@ -0,0 +1,254 @@
+//! Git Smart HTTP Protocol Implementation
+//!
+//! This module implements the Git pkt-line format and protocol utilities.
+//!
+//! # Pkt-line Format
+//!
+//! A pkt-line is a variable length binary string with a 4-byte length prefix:
+//! - First 4 bytes: hex digits representing total length (including these 4 bytes)
+//! - Remaining bytes: payload data
+//! - Special case "0000": flush packet (end of section)
+//!
+//! # References
+//! - https://git-scm.com/docs/protocol-common#_pkt_line_format
+
+use std::fmt;
+
+/// Represents a Git pkt-line packet
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum PktLine {
+    /// Data packet with payload
+    Data(Vec<u8>),
+    /// Flush packet (0000)
+    Flush,
+}
+
+impl PktLine {
+    /// Create a data packet from bytes
+    pub fn data(data: impl Into<Vec<u8>>) -> Self {
+        Self::Data(data.into())
+    }
+
+    /// Create a flush packet
+    pub fn flush() -> Self {
+        Self::Flush
+    }
+
+    /// Encode this packet to wire format
+    pub fn encode(&self) -> Vec<u8> {
+        match self {
+            PktLine::Flush => b"0000".to_vec(),
+            PktLine::Data(data) => {
+                let len = data.len() + 4;
+                let mut result = Vec::with_capacity(len);
+                result.extend_from_slice(format!("{:04x}", len).as_bytes());
+                result.extend_from_slice(data);
+                result
+            }
+        }
+    }
+
+    /// Parse a single pkt-line from bytes
+    /// Returns (packet, remaining_bytes)
+    pub fn parse(input: &[u8]) -> Result<(Self, &[u8]), ProtocolError> {
+        if input.len() < 4 {
+            return Err(ProtocolError::InsufficientData);
+        }
+
+        let len_str = std::str::from_utf8(&input[0..4])
+            .map_err(|_| ProtocolError::InvalidLength)?;
+        
+        let len = u16::from_str_radix(len_str, 16)
+            .map_err(|_| ProtocolError::InvalidLength)? as usize;
+
+        if len == 0 {
+            // Flush packet
+            return Ok((PktLine::Flush, &input[4..]));
+        }
+
+        if len < 4 {
+            return Err(ProtocolError::InvalidLength);
+        }
+
+        if input.len() < len {
+            return Err(ProtocolError::InsufficientData);
+        }
+
+        let data = input[4..len].to_vec();
+        Ok((PktLine::Data(data), &input[len..]))
+    }
+
+    /// Parse all pkt-lines from bytes
+    pub fn parse_all(mut input: &[u8]) -> Result<Vec<Self>, ProtocolError> {
+        let mut packets = Vec::new();
+        
+        while !input.is_empty() {
+            let (packet, remaining) = Self::parse(input)?;
+            let is_flush = matches!(packet, PktLine::Flush);
+            packets.push(packet);
+            input = remaining;
+            
+            // Stop at flush packet
+            if is_flush {
+                break;
+            }
+        }
+        
+        Ok(packets)
+    }
+}
+
+/// Errors that can occur during protocol parsing
+#[derive(Debug)]
+pub enum ProtocolError {
+    /// Not enough data to parse a complete packet
+    InsufficientData,
+    /// Invalid length prefix
+    InvalidLength,
+    /// Invalid UTF-8 in packet data
+    InvalidUtf8,
+    /// IO error
+    Io(std::io::Error),
+}
+
+impl fmt::Display for ProtocolError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::InsufficientData => write!(f, "insufficient data for pkt-line"),
+            Self::InvalidLength => write!(f, "invalid pkt-line length"),
+            Self::InvalidUtf8 => write!(f, "invalid UTF-8 in pkt-line"),
+            Self::Io(e) => write!(f, "IO error: {}", e),
+        }
+    }
+}
+
+impl std::error::Error for ProtocolError {}
+
+impl From<std::io::Error> for ProtocolError {
+    fn from(e: std::io::Error) -> Self {
+        Self::Io(e)
+    }
+}
+
+/// Git service type
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum GitService {
+    /// Upload pack (clone/fetch)
+    UploadPack,
+    /// Receive pack (push)
+    ReceivePack,
+}
+
+impl GitService {
+    /// Parse service from query parameter
+    pub fn from_query_param(service: &str) -> Option<Self> {
+        match service {
+            "git-upload-pack" => Some(Self::UploadPack),
+            "git-receive-pack" => Some(Self::ReceivePack),
+            _ => None,
+        }
+    }
+
+    /// Get the service name as used in Git protocol
+    pub fn as_str(&self) -> &'static str {
+        match self {
+            Self::UploadPack => "git-upload-pack",
+            Self::ReceivePack => "git-receive-pack",
+        }
+    }
+
+    /// Get the content type for the service advertisement
+    pub fn advertisement_content_type(&self) -> &'static str {
+        match self {
+            Self::UploadPack => "application/x-git-upload-pack-advertisement",
+            Self::ReceivePack => "application/x-git-receive-pack-advertisement",
+        }
+    }
+
+    /// Get the content type for the service result
+    pub fn result_content_type(&self) -> &'static str {
+        match self {
+            Self::UploadPack => "application/x-git-upload-pack-result",
+            Self::ReceivePack => "application/x-git-receive-pack-result",
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_pktline_encode_flush() {
+        let pkt = PktLine::flush();
+        assert_eq!(pkt.encode(), b"0000");
+    }
+
+    #[test]
+    fn test_pktline_encode_data() {
+        let pkt = PktLine::data(b"hello");
+        assert_eq!(pkt.encode(), b"0009hello");
+    }
+
+    #[test]
+    fn test_pktline_parse_flush() {
+        let (pkt, remaining) = PktLine::parse(b"0000extra").unwrap();
+        assert_eq!(pkt, PktLine::Flush);
+        assert_eq!(remaining, b"extra");
+    }
+
+    #[test]
+    fn test_pktline_parse_data() {
+        let (pkt, remaining) = PktLine::parse(b"0009helloworld").unwrap();
+        assert_eq!(pkt, PktLine::data(b"hello"));
+        assert_eq!(remaining, b"world");
+    }
+
+    #[test]
+    fn test_pktline_parse_insufficient_data() {
+        let result = PktLine::parse(b"000");
+        assert!(matches!(result, Err(ProtocolError::InsufficientData)));
+    }
+
+    #[test]
+    fn test_pktline_parse_invalid_length() {
+        let result = PktLine::parse(b"xxxx");
+        assert!(matches!(result, Err(ProtocolError::InvalidLength)));
+    }
+
+    #[test]
+    fn test_pktline_parse_all() {
+        let input = b"0009hello000aworld\n0000";
+        let packets = PktLine::parse_all(input).unwrap();
+        assert_eq!(packets.len(), 3);
+        assert_eq!(packets[0], PktLine::data(b"hello"));
+        assert_eq!(packets[1], PktLine::data(b"world\n"));
+        assert_eq!(packets[2], PktLine::Flush);
+    }
+
+    #[test]
+    fn test_git_service_from_query() {
+        assert_eq!(
+            GitService::from_query_param("git-upload-pack"),
+            Some(GitService::UploadPack)
+        );
+        assert_eq!(
+            GitService::from_query_param("git-receive-pack"),
+            Some(GitService::ReceivePack)
+        );
+        assert_eq!(GitService::from_query_param("invalid"), None);
+    }
+
+    #[test]
+    fn test_git_service_content_types() {
+        let upload = GitService::UploadPack;
+        assert_eq!(
+            upload.advertisement_content_type(),
+            "application/x-git-upload-pack-advertisement"
+        );
+        assert_eq!(
+            upload.result_content_type(),
+            "application/x-git-upload-pack-result"
+        );
+    }
+}
\ No newline at end of file
diff --git a/src/git/subprocess.rs b/src/git/subprocess.rs
new file mode 100644
index 0000000..96eed26
--- /dev/null
+++ b/src/git/subprocess.rs
@@ -0,0 +1,140 @@
+//! Git Subprocess Management
+//!
+//! This module provides utilities for spawning and managing Git subprocesses
+//! for upload-pack and receive-pack operations.
+
+use std::path::Path;
+use std::process::Stdio;
+use tokio::io::{AsyncRead, AsyncWrite};
+use tokio::process::{Child, Command};
+
+use super::protocol::GitService;
+
+/// Git subprocess wrapper
+pub struct GitSubprocess {
+    child: Child,
+}
+
+impl GitSubprocess {
+    /// Spawn a git subprocess for the given service and repository path
+    ///
+    /// # Arguments
+    /// * `service` - The Git service (upload-pack or receive-pack)
+    /// * `repo_path` - Path to the bare Git repository
+    /// * `advertise` - If true, run with --advertise-refs flag
+    pub fn spawn(
+        service: GitService,
+        repo_path: impl AsRef<Path>,
+        advertise: bool,
+    ) -> std::io::Result<Self> {
+        let repo_path = repo_path.as_ref();
+        
+        let mut cmd = Command::new("git");
+        cmd.arg(service.as_str());
+        
+        if advertise {
+            cmd.arg("--advertise-refs");
+        }
+        
+        cmd.arg("--stateless-rpc");
+        cmd.arg(repo_path);
+        
+        cmd.stdin(Stdio::piped());
+        cmd.stdout(Stdio::piped());
+        cmd.stderr(Stdio::piped());
+        
+        let child = cmd.spawn()?;
+        
+        Ok(Self { child })
+    }
+
+    /// Get a mutable reference to stdin
+    pub fn stdin(&mut self) -> Option<&mut (impl AsyncWrite + Unpin)> {
+        self.child.stdin.as_mut()
+    }
+
+    /// Get a mutable reference to stdout
+    pub fn stdout(&mut self) -> Option<&mut (impl AsyncRead + Unpin)> {
+        self.child.stdout.as_mut()
+    }
+
+    /// Get a mutable reference to stderr
+    pub fn stderr(&mut self) -> Option<&mut (impl AsyncRead + Unpin)> {
+        self.child.stderr.as_mut()
+    }
+
+    /// Take ownership of stdin
+    pub fn take_stdin(&mut self) -> Option<impl AsyncWrite> {
+        self.child.stdin.take()
+    }
+
+    /// Take ownership of stdout
+    pub fn take_stdout(&mut self) -> Option<impl AsyncRead> {
+        self.child.stdout.take()
+    }
+
+    /// Take ownership of stderr  
+    pub fn take_stderr(&mut self) -> Option<impl AsyncRead> {
+        self.child.stderr.take()
+    }
+
+    /// Wait for the subprocess to complete
+    pub async fn wait(mut self) -> std::io::Result<std::process::ExitStatus> {
+        self.child.wait().await
+    }
+
+    /// Kill the subprocess
+    pub async fn kill(&mut self) -> std::io::Result<()> {
+        self.child.kill().await
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use tempfile::TempDir;
+    use std::process::Command as StdCommand;
+
+    fn create_bare_repo() -> TempDir {
+        let dir = TempDir::new().unwrap();
+        let status = StdCommand::new("git")
+            .args(["init", "--bare"])
+            .arg(dir.path())
+            .status()
+            .expect("Failed to run git init");
+        assert!(status.success());
+        dir
+    }
+
+    #[tokio::test]
+    async fn test_spawn_upload_pack_advertise() {
+        let repo = create_bare_repo();
+        let mut proc = GitSubprocess::spawn(
+            GitService::UploadPack,
+            repo.path(),
+            true,
+        ).expect("Failed to spawn git");
+
+        // Should have spawned successfully
+        assert!(proc.stdout().is_some());
+        assert!(proc.stdin().is_some());
+
+        // Clean up
+        let _ = proc.kill().await;
+    }
+
+    #[tokio::test]
+    async fn test_spawn_receive_pack() {
+        let repo = create_bare_repo();
+        let mut proc = GitSubprocess::spawn(
+            GitService::ReceivePack,
+            repo.path(),
+            false,
+        ).expect("Failed to spawn git");
+
+        assert!(proc.stdout().is_some());
+        assert!(proc.stdin().is_some());
+
+        let _ = proc.kill().await;
+    }
+}
\ No newline at end of file