gitlabhq/gitlab-shell

package lfsauthenticate

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

    "gitlab.com/gitlab-org/labkit/log"

    "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"
)

const (
    downloadOperation = "download"
    uploadOperation   = "upload"
)

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

type PayloadHeader struct {
    Auth string `json:"Authorization"`
}

type Payload struct {
    Header    PayloadHeader `json:"header"`
    Href      string        `json:"href"`
    ExpiresIn int           `json:"expires_in,omitempty"`
}

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-authenticate 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
    }

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

    payload, err := c.authenticate(ctx, operation, repo, accessResponse.UserID)
    if err != nil {
        // return nothing just like Ruby's GitlabShell#lfs_authenticate does
        log.WithContextFields(
            ctx,
            log.Fields{"operation": operation, "repo": repo, "user_id": accessResponse.UserID},
        ).WithError(err).Debug("lfsauthenticate: execute: LFS authentication failed")

        return ctxWithLogData, nil
    }

    fmt.Fprintf(c.ReadWriter.Out, "%s\n", payload)

    return ctxWithLogData, nil
}

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

    switch operation {
    case downloadOperation:
        action = commandargs.UploadPack
    case 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, userId string) ([]byte, 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 := base64.StdEncoding.EncodeToString([]byte(response.Username + ":" + response.LfsToken))
    payload := &Payload{
        Header:    PayloadHeader{Auth: "Basic " + basicAuth},
        Href:      response.RepoPath + "/info/lfs",
        ExpiresIn: response.ExpiresIn,
    }

    return json.Marshal(payload)
}