Make git_hooks_handle portable ish?

2 files changed, 338 insertions, 0 deletions

diff --git a/git_hooks_handle.go b/git_hooks_handle_linux.go
index f41507c..40ba1ac 100644
--- a/git_hooks_handle.go
+++ b/git_hooks_handle_linux.go
@@ -1,5 +1,7 @@
 // SPDX-License-Identifier: AGPL-3.0-only
 // SPDX-FileContributor: Runxi Yu <https://runxiyu.org>
+//
+//go:build linux
 
 package main
 
diff --git a/git_hooks_handle_other.go b/git_hooks_handle_other.go
new file mode 100644
index 0000000..8bd1f7a
--- /dev/null
+++ b/git_hooks_handle_other.go
@@ -0,0 +1,336 @@
+// SPDX-License-Identifier: AGPL-3.0-only
+// SPDX-FileContributor: Runxi Yu <https://runxiyu.org>
+//
+//go:build !linux
+
+package main
+
+import (
+	"bytes"
+	"context"
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"io"
+	"net"
+	"path/filepath"
+	"strconv"
+	"strings"
+
+	"github.com/go-git/go-git/v5/plumbing"
+	"github.com/go-git/go-git/v5/plumbing/object"
+	"github.com/jackc/pgx/v5"
+	"go.lindenii.runxiyu.org/lindenii-common/ansiec"
+	"go.lindenii.runxiyu.org/lindenii-common/clog"
+)
+
+var (
+	errGetFD = errors.New("unable to get file descriptor")
+)
+
+// hooksHandler handles a connection from hookc via the
+// unix socket.
+func hooksHandler(conn net.Conn) {
+	var ctx context.Context
+	var cancel context.CancelFunc
+	var err error
+	var cookie []byte
+	var packPass packPass
+	var sshStderr io.Writer
+	var hookRet byte
+
+	defer conn.Close()
+	ctx, cancel = context.WithCancel(context.Background())
+	defer cancel()
+
+	// TODO: Validate that the connection is from the right user.
+
+	cookie = make([]byte, 64)
+	if _, err = conn.Read(cookie); err != nil {
+		if _, err = conn.Write([]byte{1}); err != nil {
+			return
+		}
+		writeRedError(conn, "\nFailed to read cookie: %v", err)
+		return
+	}
+
+	{
+		var ok bool
+		packPass, ok = packPasses.Load(string(cookie))
+		if !ok {
+			if _, err = conn.Write([]byte{1}); err != nil {
+				return
+			}
+			writeRedError(conn, "\nInvalid handler cookie")
+			return
+		}
+	}
+
+	sshStderr = packPass.session.Stderr()
+
+	_, _ = sshStderr.Write([]byte{'\n'})
+
+	hookRet = func() byte {
+		var argc64 uint64
+		if err = binary.Read(conn, binary.NativeEndian, &argc64); err != nil {
+			writeRedError(sshStderr, "Failed to read argc: %v", err)
+			return 1
+		}
+		var args []string
+		for range argc64 {
+			var arg bytes.Buffer
+			for {
+				nextByte := make([]byte, 1)
+				n, err := conn.Read(nextByte)
+				if err != nil || n != 1 {
+					writeRedError(sshStderr, "Failed to read arg: %v", err)
+					return 1
+				}
+				if nextByte[0] == 0 {
+					break
+				}
+				arg.WriteByte(nextByte[0])
+			}
+			args = append(args, arg.String())
+		}
+
+		gitEnv := make(map[string]string)
+		for {
+			var envLine bytes.Buffer
+			for {
+				nextByte := make([]byte, 1)
+				n, err := conn.Read(nextByte)
+				if err != nil || n != 1 {
+					writeRedError(sshStderr, "Failed to read environment variable: %v", err)
+					return 1
+				}
+				if nextByte[0] == 0 {
+					break
+				}
+				envLine.WriteByte(nextByte[0])
+			}
+			if envLine.Len() == 0 {
+				break
+			}
+			kv := envLine.String()
+			parts := strings.SplitN(kv, "=", 2)
+			if len(parts) < 2 {
+				writeRedError(sshStderr, "Invalid environment variable line: %v", kv)
+				return 1
+			}
+			gitEnv[parts[0]] = parts[1]
+		}
+
+		var stdin bytes.Buffer
+		if _, err = io.Copy(&stdin, conn); err != nil {
+			writeRedError(conn, "Failed to read to the stdin buffer: %v", err)
+		}
+
+		switch filepath.Base(args[0]) {
+		case "pre-receive":
+			if packPass.directAccess {
+				return 0
+			}
+			allOK := true
+			for {
+				var line, oldOID, rest, newIOID, refName string
+				var found bool
+				var oldHash, newHash plumbing.Hash
+				var oldCommit, newCommit *object.Commit
+				var pushOptCount int
+
+				pushOptCount, err = strconv.Atoi(gitEnv["GIT_PUSH_OPTION_COUNT"])
+				if err != nil {
+					writeRedError(sshStderr, "Failed to parse GIT_PUSH_OPTION_COUNT: %v", err)
+					return 1
+				}
+
+				// TODO: Allow existing users (even if they are already federated or registered) to add a federated user ID... though perhaps this should be in the normal SSH interface instead of the git push interface?
+				// Also it'd be nice to be able to combine users or whatever
+				if packPass.contribReq == "federated" && packPass.userType != "federated" && packPass.userType != "registered" {
+					if pushOptCount == 0 {
+						writeRedError(sshStderr, "This repo requires contributors to be either federated or registered users. You must supply your federated user ID as a push option. For example, git push -o fedid=sr.ht:runxiyu")
+						return 1
+					}
+					for pushOptIndex := range pushOptCount {
+						pushOpt, ok := gitEnv[fmt.Sprintf("GIT_PUSH_OPTION_%d", pushOptIndex)]
+						if !ok {
+							writeRedError(sshStderr, "Failed to get push option %d", pushOptIndex)
+							return 1
+						}
+						if strings.HasPrefix(pushOpt, "fedid=") {
+							fedUserID := strings.TrimPrefix(pushOpt, "fedid=")
+							service, username, found := strings.Cut(fedUserID, ":")
+							if !found {
+								writeRedError(sshStderr, "Invalid federated user identifier %#v does not contain a colon", fedUserID)
+								return 1
+							}
+
+							ok, err := fedauth(ctx, packPass.userID, service, username, packPass.pubkey)
+							if err != nil {
+								writeRedError(sshStderr, "Failed to verify federated user identifier %#v: %v", fedUserID, err)
+								return 1
+							}
+							if !ok {
+								writeRedError(sshStderr, "Failed to verify federated user identifier %#v: you don't seem to be on the list", fedUserID)
+								return 1
+							}
+
+							break
+						}
+						if pushOptIndex == pushOptCount-1 {
+							writeRedError(sshStderr, "This repo requires contributors to be either federated or registered users. You must supply your federated user ID as a push option. For example, git push -o fedid=sr.ht:runxiyu")
+							return 1
+						}
+					}
+				}
+
+				line, err = stdin.ReadString('\n')
+				if errors.Is(err, io.EOF) {
+					break
+				} else if err != nil {
+					writeRedError(sshStderr, "Failed to read pre-receive line: %v", err)
+					return 1
+				}
+				line = line[:len(line)-1]
+
+				oldOID, rest, found = strings.Cut(line, " ")
+				if !found {
+					writeRedError(sshStderr, "Invalid pre-receive line: %v", line)
+					return 1
+				}
+
+				newIOID, refName, found = strings.Cut(rest, " ")
+				if !found {
+					writeRedError(sshStderr, "Invalid pre-receive line: %v", line)
+					return 1
+				}
+
+				if strings.HasPrefix(refName, "refs/heads/contrib/") {
+					if allZero(oldOID) { // New branch
+						fmt.Fprintln(sshStderr, ansiec.Blue+"POK"+ansiec.Reset, refName)
+						var newMRID int
+
+						if packPass.userID != 0 {
+							err = database.QueryRow(ctx,
+								"INSERT INTO merge_requests (repo_id, creator, source_ref, status) VALUES ($1, $2, $3, 'open') RETURNING id",
+								packPass.repoID, packPass.userID, strings.TrimPrefix(refName, "refs/heads/"),
+							).Scan(&newMRID)
+						} else {
+							err = database.QueryRow(ctx,
+								"INSERT INTO merge_requests (repo_id, source_ref, status) VALUES ($1, $2, 'open') RETURNING id",
+								packPass.repoID, strings.TrimPrefix(refName, "refs/heads/"),
+							).Scan(&newMRID)
+						}
+						if err != nil {
+							writeRedError(sshStderr, "Error creating merge request: %v", err)
+							return 1
+						}
+						mergeRequestWebURL := fmt.Sprintf("%s/contrib/%d/", genHTTPRemoteURL(packPass.groupPath, packPass.repoName), newMRID)
+						fmt.Fprintln(sshStderr, ansiec.Blue+"Created merge request at", mergeRequestWebURL+ansiec.Reset)
+						select {
+						case ircSendBuffered <- "PRIVMSG #chat :New merge request at " + mergeRequestWebURL:
+						default:
+							clog.Error("IRC SendQ exceeded")
+						}
+					} else { // Existing contrib branch
+						var existingMRUser int
+						var isAncestor bool
+
+						err = database.QueryRow(ctx,
+							"SELECT COALESCE(creator, 0) FROM merge_requests WHERE source_ref = $1 AND repo_id = $2",
+							strings.TrimPrefix(refName, "refs/heads/"), packPass.repoID,
+						).Scan(&existingMRUser)
+						if err != nil {
+							if errors.Is(err, pgx.ErrNoRows) {
+								writeRedError(sshStderr, "No existing merge request for existing contrib branch: %v", err)
+							} else {
+								writeRedError(sshStderr, "Error querying for existing merge request: %v", err)
+							}
+							return 1
+						}
+						if existingMRUser == 0 {
+							allOK = false
+							fmt.Fprintln(sshStderr, ansiec.Red+"NAK"+ansiec.Reset, refName, "(branch belongs to unowned MR)")
+							continue
+						}
+
+						if existingMRUser != packPass.userID {
+							allOK = false
+							fmt.Fprintln(sshStderr, ansiec.Red+"NAK"+ansiec.Reset, refName, "(branch belongs another user's MR)")
+							continue
+						}
+
+						oldHash = plumbing.NewHash(oldOID)
+
+						if oldCommit, err = packPass.repo.CommitObject(oldHash); err != nil {
+							writeRedError(sshStderr, "Daemon failed to get old commit: %v", err)
+							return 1
+						}
+
+						// Potential BUG: I'm not sure if new_commit is guaranteed to be
+						// detectable as they haven't been merged into the main repo's
+						// objects yet. But it seems to work, and I don't think there's
+						// any reason for this to only work intermitently.
+						newHash = plumbing.NewHash(newIOID)
+						if newCommit, err = packPass.repo.CommitObject(newHash); err != nil {
+							writeRedError(sshStderr, "Daemon failed to get new commit: %v", err)
+							return 1
+						}
+
+						if isAncestor, err = oldCommit.IsAncestor(newCommit); err != nil {
+							writeRedError(sshStderr, "Daemon failed to check if old commit is ancestor: %v", err)
+							return 1
+						}
+
+						if !isAncestor {
+							// TODO: Create MR snapshot ref instead
+							allOK = false
+							fmt.Fprintln(sshStderr, ansiec.Red+"NAK"+ansiec.Reset, refName, "(force pushes are not supported yet)")
+							continue
+						}
+
+						fmt.Fprintln(sshStderr, ansiec.Blue+"POK"+ansiec.Reset, refName)
+					}
+				} else { // Non-contrib branch
+					allOK = false
+					fmt.Fprintln(sshStderr, ansiec.Red+"NAK"+ansiec.Reset, refName, "(you cannot push to branches outside of contrib/*)")
+				}
+			}
+
+			fmt.Fprintln(sshStderr)
+			if allOK {
+				fmt.Fprintln(sshStderr, "Overall "+ansiec.Green+"ACK"+ansiec.Reset+" (all checks passed)")
+				return 0
+			}
+			fmt.Fprintln(sshStderr, "Overall "+ansiec.Red+"NAK"+ansiec.Reset+" (one or more branches failed checks)")
+			return 1
+		default:
+			fmt.Fprintln(sshStderr, ansiec.Red+"Invalid hook:", args[0]+ansiec.Reset)
+			return 1
+		}
+	}()
+
+	fmt.Fprintln(sshStderr)
+
+	_, _ = conn.Write([]byte{hookRet})
+}
+
+func serveGitHooks(listener net.Listener) error {
+	for {
+		conn, err := listener.Accept()
+		if err != nil {
+			return err
+		}
+		go hooksHandler(conn)
+	}
+}
+
+func allZero(s string) bool {
+	for _, r := range s {
+		if r != '0' {
+			return false
+		}
+	}
+	return true
+}