Artifact [e7273ffe7d]

Artifact e7273ffe7d0b0135e54eff59415d56890d1aaff286942f55e12f3a8375e2b781:

• File repo_sync.go — part of check-in [21a447e620] at 2026-07-25 02:15:37 on branch trunk — fix: decode sync replies by the wire's real Content-Type, not a hardcoded assumption (#165)

  The public byte-oriented Transport discarded the reply's Content-Type, and the adapter bridging it to the internal xfer decoder hardcoded the §4.1 compressed container framing unconditionally. That assumption holds only when both peers are this implementation (Message.Encode always emits the compressed container). Against a peer that legitimately replies uncompressed -- a real Fossil clone-v3 reply uses plain card text -- the adapter read the first four bytes of the card text (`prag` from `pragma server-version`) as a big-endian length prefix and failed on exchange round 0 with "declared container length ... exceeds ... bytes".

  Add an optional FramedTransport interface a Transport may also implement to report the framing signal (e.g. an HTTP Content-Type) it observed on a reply, via a per-call RoundTripFramed return value -- no shared mutable state, so a reused transport stays safe. httpTransport implements it by returning the HTTP response Content-Type. transportAdapter.Exchange decodes by that signal when the transport reports one and otherwise falls back to the compressed framing, so MockTransport / TransportFunc and any fixed-framing peer transport keep working unchanged.

  The low-level xfer.Decode framing selection is unchanged. No trial-and-error framing detection is reintroduced. (user: [email protected], size: 7595) [annotate] [blame] [check-ins using]

package libfossil

import (
	"context"
	"fmt"
	"net/http"

	internalsync "github.com/danmestas/go-libfossil/internal/sync"
	"github.com/danmestas/go-libfossil/internal/xfer"
)

// SyncOpts configures a sync operation.
type SyncOpts struct {
	Push        bool
	Pull        bool
	UV          bool
	ProjectCode string
	ServerCode  string
	User        string
	Password    string
	PeerID      string // identifies this leaf agent instance
	MaxSend     int
	XTableSync  bool // enable extension table sync (peer_registry, etc.)
	Private     bool // enable private artifact sync
	Observer    SyncObserver
	Buggify     BuggifyChecker
}

// SyncResult describes the outcome of a sync session.
type SyncResult struct {
	Rounds       int
	FilesSent    int
	FilesRecvd   int
	UVFilesSent  int
	UVFilesRecvd int
	UVGimmesSent int
	BytesSent    int64
	BytesRecvd   int64
	Errors       []string
}

// HandleOpts configures server-side sync handling.
type HandleOpts struct {
	Observer SyncObserver
	Buggify  BuggifyChecker
}

// CloneOpts configures a clone operation.
type CloneOpts struct {
	User     string
	Password string
	Observer SyncObserver
	Buggify  BuggifyChecker // fault injection for DST (nil = no faults)
}

// transportAdapter bridges the public byte-level Transport to the internal
// xfer.Message-based sync.Transport.
type transportAdapter struct {
	pub Transport
}

func (a *transportAdapter) Exchange(ctx context.Context, req *xfer.Message) (*xfer.Message, error) {
	payload, err := req.Encode()
	if err != nil {
		return nil, fmt.Errorf("libfossil: transport encode: %w", err)
	}
	// When the transport can report the reply's framing signal (e.g. an HTTP
	// Content-Type), decode by that signal — a §4-conforming peer may reply
	// with either framing, and a real Fossil clone reply is uncompressed. §4
	// framing selection lives in xfer.Decode.
	if ft, ok := a.pub.(FramedTransport); ok {
		respBytes, contentType, err := ft.RoundTripFramed(ctx, payload)
		if err != nil {
			return nil, err
		}
		return xfer.Decode(respBytes, contentType)
	}
	respBytes, err := a.pub.RoundTrip(ctx, payload)
	if err != nil {
		return nil, err
	}
	// The transport reports no framing signal. Both ends are libfossil and
	// reply via Message.Encode, which always produces the §4.1 compressed
	// container, so the framing is fixed by construction rather than negotiated.
	return xfer.Decode(respBytes, xfer.ContentTypeCompressed)
}

// observerAdapter bridges the public context-free SyncObserver to the internal
// context-carrying sync.Observer.
type observerAdapter struct {
	pub SyncObserver
}

func (a *observerAdapter) Started(ctx context.Context, info internalsync.SessionStart) context.Context {
	a.pub.Started(SessionStart{
		ProjectCode: info.ProjectCode,
		Push:        info.Push,
		Pull:        info.Pull,
		UV:          info.UV,
	})
	return ctx
}

func (a *observerAdapter) RoundStarted(ctx context.Context, round int) context.Context {
	a.pub.RoundStarted(round)
	return ctx
}

func (a *observerAdapter) RoundCompleted(_ context.Context, round int, stats internalsync.RoundStats) {
	a.pub.RoundCompleted(round, RoundStats{
		FilesSent:  stats.FilesSent,
		FilesRecvd: stats.FilesReceived,
		BytesSent:  int(stats.BytesSent),
		BytesRecvd: int(stats.BytesReceived),
		Gimmes:     stats.GimmesSent,
		IGots:      stats.IgotsSent,
	})
}

func (a *observerAdapter) Completed(_ context.Context, info internalsync.SessionEnd, _ error) {
	a.pub.Completed(SessionEnd{
		Rounds:     info.Rounds,
		FilesSent:  info.FilesSent,
		FilesRecvd: info.FilesRecvd,
	})
}

func (a *observerAdapter) Error(_ context.Context, err error) {
	a.pub.Error(err)
}

func (a *observerAdapter) HandleStarted(ctx context.Context, info internalsync.HandleStart) context.Context {
	a.pub.HandleStarted(HandleStart{
		RemoteAddr: info.RemoteAddr,
	})
	return ctx
}

func (a *observerAdapter) HandleCompleted(_ context.Context, info internalsync.HandleEnd) {
	a.pub.HandleCompleted(HandleEnd{
		FilesSent:  info.FilesSent,
		FilesRecvd: info.FilesReceived,
	})
}

func (a *observerAdapter) TableSyncStarted(_ context.Context, info internalsync.TableSyncStart) {
	a.pub.TableSyncStarted(TableSyncStart{
		Table: info.Table,
	})
}

func (a *observerAdapter) TableSyncCompleted(_ context.Context, info internalsync.TableSyncEnd) {
	a.pub.TableSyncCompleted(TableSyncEnd{
		Table:     info.Table,
		RowsSent:  info.Sent,
		RowsRecvd: info.Received,
	})
}

// adaptObserver returns an internal sync.Observer wrapping the public SyncObserver.
// Returns nil if pub is nil (internal packages treat nil as nop).
func adaptObserver(pub SyncObserver) internalsync.Observer {
	if pub == nil {
		return nil
	}
	return &observerAdapter{pub: pub}
}

// Sync runs a sync session against the given transport.
func (r *Repo) Sync(ctx context.Context, t Transport, opts SyncOpts) (*SyncResult, error) {
	adapter := &transportAdapter{pub: t}
	iOpts := internalsync.SyncOpts{
		Push:        opts.Push,
		Pull:        opts.Pull,
		UV:          opts.UV,
		ProjectCode: opts.ProjectCode,
		ServerCode:  opts.ServerCode,
		User:        opts.User,
		Password:    opts.Password,
		PeerID:      opts.PeerID,
		MaxSend:     opts.MaxSend,
		XTableSync:  opts.XTableSync,
		Private:     opts.Private,
		Observer:    adaptObserver(opts.Observer),
		Buggify:     opts.Buggify,
	}
	res, err := internalsync.Sync(ctx, r.inner, adapter, iOpts)
	if err != nil {
		return convertSyncResult(res), fmt.Errorf("libfossil: sync: %w", err)
	}
	return convertSyncResult(res), nil
}

func convertSyncResult(r *internalsync.SyncResult) *SyncResult {
	if r == nil {
		return nil
	}
	return &SyncResult{
		Rounds:       r.Rounds,
		FilesSent:    r.FilesSent,
		FilesRecvd:   r.FilesRecvd,
		UVFilesSent:  r.UVFilesSent,
		UVFilesRecvd: r.UVFilesRecvd,
		UVGimmesSent: r.UVGimmesSent,
		BytesSent:    r.BytesSent,
		BytesRecvd:   r.BytesRecvd,
		Errors:       r.Errors,
	}
}

// HandleSync processes an incoming xfer request (server-side).
// The payload is a raw xfer-encoded byte slice; the response is also raw bytes.
func (r *Repo) HandleSync(ctx context.Context, payload []byte) ([]byte, error) {
	return r.HandleSyncWithOpts(ctx, payload, HandleOpts{})
}

// HandleSyncWithOpts processes an incoming xfer request with optional configuration.
func (r *Repo) HandleSyncWithOpts(ctx context.Context, payload []byte, opts HandleOpts) ([]byte, error) {
	// The payload arrives without a Content-Type; a libfossil peer always sends
	// the §4.1 compressed container (Message.Encode), so the framing is fixed.
	msg, err := xfer.Decode(payload, xfer.ContentTypeCompressed)
	if err != nil {
		return nil, fmt.Errorf("libfossil: decode xfer: %w", err)
	}
	iOpts := internalsync.HandleOpts{
		Observer: adaptObserver(opts.Observer),
	}
	if opts.Buggify != nil {
		iOpts.Buggify = opts.Buggify
	}
	resp, err := internalsync.HandleSyncWithOpts(ctx, r.inner, msg, iOpts)
	if err != nil {
		return nil, fmt.Errorf("libfossil: handle sync: %w", err)
	}
	return resp.Encode()
}

// XferHandler returns an http.HandlerFunc that decodes Fossil xfer requests,
// dispatches to HandleSync, and encodes the response. Use this to compose
// a custom mux alongside operational endpoints (e.g., /healthz).
func (r *Repo) XferHandler() http.HandlerFunc {
	h := internalsync.HandleSync
	return internalsync.XferHandler(r.inner, h)
}

// ServeHTTP starts an HTTP server that accepts Fossil xfer requests.
// Blocks until ctx is cancelled.
func (r *Repo) ServeHTTP(ctx context.Context, addr string) error {
	return internalsync.ServeHTTP(ctx, addr, r.inner, internalsync.HandleSync)
}