gitlabhq/gitlab-shell

package lfstransfer

import (
    "context"
    "encoding/base64"
    "fmt"

    "github.com/charmbracelet/git-lfs-transfer/transfer"
    "gitlab.com/gitlab-org/gitlab-shell/v14/internal/command"
    "gitlab.com/gitlab-org/gitlab-shell/v14/internal/command/commandargs"
    "gitlab.com/gitlab-org/gitlab-shell/v14/internal/command/readwriter"
    "gitlab.com/gitlab-org/gitlab-shell/v14/internal/command/shared/accessverifier"
    "gitlab.com/gitlab-org/gitlab-shell/v14/internal/command/shared/disallowedcommand"
    "gitlab.com/gitlab-org/gitlab-shell/v14/internal/config"
    "gitlab.com/gitlab-org/gitlab-shell/v14/internal/gitlabnet/lfsauthenticate"
    "gitlab.com/gitlab-org/labkit/log"
)

var (
    capabilities = []string{
        "version=1",
        "locking",
    }
)

type Command struct {
    Config     *config.Config
    Args       *commandargs.Shell
    ReadWriter *readwriter.ReadWriter
}

func (c *Command) Execute(ctx context.Context) (context.Context, error) {
    args := c.Args.SshArgs
    if len(args) != 3 {
        return ctx, disallowedcommand.Error
    }

    // e.g. git-lfs-transfer user/repo.git download
    repo := args[1]
    operation := args[2]

    action, err := actionFromOperation(operation)
    if err != nil {
        return ctx, err
    }

    accessResponse, err := c.verifyAccess(ctx, action, repo)
    if err != nil {
        return ctx, err
    }

    ctxWithLogData := context.WithValue(ctx, "logData", command.NewLogData(
        accessResponse.Gitaly.Repo.GlProjectPath,
        accessResponse.Username,
        accessResponse.ProjectID,
        accessResponse.RootNamespaceID,
    ))

    log.WithContextFields(ctxWithLogData, log.Fields{"action": action}).Info("processing action")

    auth, err := c.authenticate(ctx, operation, repo, accessResponse.UserID)
    if err != nil {
        return ctxWithLogData, err
    }

    logger := NewWrappedLoggerForGitLFSTransfer(ctxWithLogData)

    backend, err := NewGitlabBackend(ctxWithLogData, c.Config, c.Args, auth)
    if err != nil {
        return ctxWithLogData, err
    }

    handler := transfer.NewPktline(c.ReadWriter.In, c.ReadWriter.Out, logger)

    for _, cap := range capabilities {
        if err := handler.WritePacketText(cap); err != nil {
            log.WithContextFields(ctxWithLogData, log.Fields{"capability": cap}).WithError(err).Error("error sending capability")
        }
    }

    if err := handler.WriteFlush(); err != nil {
        log.WithContextFields(ctxWithLogData, log.Fields{}).WithError(err).Error("error flushing capabilities")
    }

    p := transfer.NewProcessor(handler, backend, logger)
    defer log.WithContextFields(ctxWithLogData, log.Fields{"action": action}).Info("done processing commands")

    switch operation {
    case transfer.DownloadOperation:
        return ctxWithLogData, p.ProcessCommands(transfer.DownloadOperation)
    case transfer.UploadOperation:
        return ctxWithLogData, p.ProcessCommands(transfer.UploadOperation)
    default:
        return ctxWithLogData, fmt.Errorf("unknown operation %q", operation)
    }
}

func actionFromOperation(operation string) (commandargs.CommandType, error) {
    var action commandargs.CommandType

    switch operation {
    case transfer.DownloadOperation:
        action = commandargs.UploadPack
    case transfer.UploadOperation:
        action = commandargs.ReceivePack
    default:
        return "", disallowedcommand.Error
    }

    return action, nil
}

func (c *Command) verifyAccess(ctx context.Context, action commandargs.CommandType, repo string) (*accessverifier.Response, error) {
    cmd := accessverifier.Command{c.Config, c.Args, c.ReadWriter}

    return cmd.Verify(ctx, action, repo)
}

func (c *Command) authenticate(ctx context.Context, operation string, repo string, userID string) (*GitlabAuthentication, error) {
    client, err := lfsauthenticate.NewClient(c.Config, c.Args)
    if err != nil {
        return nil, err
    }

    response, err := client.Authenticate(ctx, operation, repo, userID)
    if err != nil {
        return nil, err
    }

    basicAuth := fmt.Sprintf("Basic %s", base64.StdEncoding.EncodeToString([]byte(fmt.Sprintf("%s:%s", response.Username, response.LfsToken))))
    return &GitlabAuthentication{
        href: fmt.Sprintf("%s/info/lfs", response.RepoPath),
        auth: basicAuth,
    }, nil
}