/
auth.go
330 lines (273 loc) · 9.98 KB
/
auth.go
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package lfsapi
import (
"encoding/base64"
"fmt"
"net/http"
"net/url"
"os"
"strings"
"github.com/git-lfs/git-lfs/v2/creds"
"github.com/git-lfs/git-lfs/v2/errors"
"github.com/git-lfs/git-lfs/v2/lfshttp"
"github.com/rubyist/tracerx"
)
var (
defaultEndpointFinder = NewEndpointFinder(nil)
)
// DoWithAuth sends an HTTP request to get an HTTP response. It attempts to add
// authentication from netrc or git's credential helpers if necessary,
// supporting basic authentication.
func (c *Client) DoWithAuth(remote string, access creds.Access, req *http.Request) (*http.Response, error) {
res, err := c.doWithAuth(remote, access, req, nil)
if errors.IsAuthError(err) {
if len(req.Header.Get("Authorization")) == 0 {
// This case represents a rejected request that
// should have been authenticated but wasn't. Do
// not count this against our redirection
// maximum.
newAccess := c.Endpoints.AccessFor(access.URL())
tracerx.Printf("api: http response indicates %q authentication. Resubmitting...", newAccess.Mode())
return c.DoWithAuth(remote, newAccess, req)
}
}
return res, err
}
// DoWithAuthNoRetry sends an HTTP request to get an HTTP response. It works in
// the same way as DoWithAuth, but will not retry the request if it fails with
// an authorization error.
func (c *Client) DoWithAuthNoRetry(remote string, access creds.Access, req *http.Request) (*http.Response, error) {
return c.doWithAuth(remote, access, req, nil)
}
// DoAPIRequestWithAuth sends an HTTP request to get an HTTP response similarly
// to DoWithAuth, but using the LFS API endpoint for the provided remote and
// operation to determine the access mode.
func (c *Client) DoAPIRequestWithAuth(remote string, req *http.Request) (*http.Response, error) {
operation := getReqOperation(req)
apiEndpoint := c.Endpoints.Endpoint(operation, remote)
access := c.Endpoints.AccessFor(apiEndpoint.Url)
return c.DoWithAuth(remote, access, req)
}
func (c *Client) doWithAuth(remote string, access creds.Access, req *http.Request, via []*http.Request) (*http.Response, error) {
req.Header = c.client.ExtraHeadersFor(req)
credWrapper, err := c.getCreds(remote, access, req)
if err != nil {
return nil, err
}
res, err := c.doWithCreds(req, credWrapper, access, via)
if err != nil {
if errors.IsAuthError(err) {
newAccess := access.Upgrade(getAuthAccess(res))
if newAccess.Mode() != access.Mode() {
c.Endpoints.SetAccess(newAccess)
}
if credWrapper.Creds != nil {
req.Header.Del("Authorization")
credWrapper.CredentialHelper.Reject(credWrapper.Creds)
}
}
}
if res != nil && res.StatusCode < 300 && res.StatusCode > 199 {
credWrapper.CredentialHelper.Approve(credWrapper.Creds)
}
return res, err
}
func (c *Client) doWithCreds(req *http.Request, credWrapper creds.CredentialHelperWrapper, access creds.Access, via []*http.Request) (*http.Response, error) {
if access.Mode() == creds.NegotiateAccess {
return c.doWithNegotiate(req, credWrapper)
}
req.Header.Set("User-Agent", lfshttp.UserAgent)
client, err := c.client.HttpClient(req.URL, access.Mode())
if err != nil {
return nil, err
}
redirectedReq, res, err := c.client.DoWithRedirect(client, req, "", via)
if err != nil || res != nil {
return res, err
}
if redirectedReq == nil {
return res, errors.New("failed to redirect request")
}
return c.doWithAuth("", access, redirectedReq, via)
}
// getCreds fills the authorization header for the given request if possible,
// from the following sources:
//
// 1. NTLM access is handled elsewhere.
// 2. Existing Authorization or ?token query tells LFS that the request is ready.
// 3. Netrc based on the hostname.
// 4. URL authentication on the Endpoint URL or the Git Remote URL.
// 5. Git Credential Helper, potentially prompting the user.
//
// There are three URLs in play, that make this a little confusing.
//
// 1. The request URL, which should be something like "https://git.com/repo.git/info/lfs/objects/batch"
// 2. The LFS API URL, which should be something like "https://git.com/repo.git/info/lfs"
// This URL used for the "lfs.URL.access" git config key, which determines
// what kind of auth the LFS server expects. Could be BasicAccess,
// NTLMAccess, NegotiateAccess, or NoneAccess, in which the Git Credential
// Helper step is skipped. We do not want to prompt the user for a password
// to fetch public repository data.
// 3. The Git Remote URL, which should be something like "https://git.com/repo.git"
// This URL is used for the Git Credential Helper. This way existing https
// Git remote credentials can be re-used for LFS.
func (c *Client) getCreds(remote string, access creds.Access, req *http.Request) (creds.CredentialHelperWrapper, error) {
ef := c.Endpoints
if ef == nil {
ef = defaultEndpointFinder
}
operation := getReqOperation(req)
apiEndpoint := ef.Endpoint(operation, remote)
if access.Mode() != creds.NegotiateAccess {
if requestHasAuth(req) || access.Mode() == creds.NoneAccess {
return creds.CredentialHelperWrapper{CredentialHelper: creds.NullCreds, Input: nil, Url: nil, Creds: nil}, nil
}
credsURL, err := getCredURLForAPI(ef, operation, remote, apiEndpoint, req)
if err != nil {
return creds.CredentialHelperWrapper{CredentialHelper: creds.NullCreds, Input: nil, Url: nil, Creds: nil}, errors.Wrap(err, "creds")
}
if credsURL == nil {
return creds.CredentialHelperWrapper{CredentialHelper: creds.NullCreds, Input: nil, Url: nil, Creds: nil}, nil
}
credWrapper := c.getGitCredsWrapper(ef, req, credsURL)
err = credWrapper.FillCreds()
if err == nil {
tracerx.Printf("Filled credentials for %s", credsURL)
setRequestAuth(req, credWrapper.Creds["username"], credWrapper.Creds["password"])
}
return credWrapper, err
}
// Negotiate only
credsURL, err := url.Parse(apiEndpoint.Url)
if err != nil {
return creds.CredentialHelperWrapper{CredentialHelper: creds.NullCreds, Input: nil, Url: nil, Creds: nil}, errors.Wrap(err, "creds")
}
// NTLM uses creds to create the session
credWrapper := c.getGitCredsWrapper(ef, req, credsURL)
return credWrapper, err
}
func (c *Client) getGitCredsWrapper(ef EndpointFinder, req *http.Request, u *url.URL) creds.CredentialHelperWrapper {
return c.credContext.GetCredentialHelper(c.Credentials, u)
}
func getCredURLForAPI(ef EndpointFinder, operation, remote string, apiEndpoint lfshttp.Endpoint, req *http.Request) (*url.URL, error) {
apiURL, err := url.Parse(apiEndpoint.Url)
if err != nil {
return nil, err
}
// if the LFS request doesn't match the current LFS url, don't bother
// attempting to set the Authorization header from the LFS or Git remote URLs.
if req.URL.Scheme != apiURL.Scheme ||
req.URL.Host != apiURL.Host {
return req.URL, nil
}
if setRequestAuthFromURL(req, apiURL) {
return nil, nil
}
if len(remote) > 0 {
if u := ef.GitRemoteURL(remote, operation == "upload"); u != "" {
schemedUrl, _ := fixSchemelessURL(u)
gitRemoteURL, err := url.Parse(schemedUrl)
if err != nil {
return nil, err
}
if gitRemoteURL.Scheme == apiURL.Scheme &&
gitRemoteURL.Host == apiURL.Host {
if setRequestAuthFromURL(req, gitRemoteURL) {
return nil, nil
}
return gitRemoteURL, nil
}
}
}
return apiURL, nil
}
// fixSchemelessURL prepends an empty scheme "//" if none was found in
// the URL and replaces the first colon with a slash in order to satisfy RFC
// 3986 §3.3, and `net/url.Parse()`.
//
// It returns a string parse-able with `net/url.Parse()` and a boolean whether
// or not an empty scheme was added.
func fixSchemelessURL(u string) (string, bool) {
if hasScheme(u) {
return u, false
}
colon := strings.Index(u, ":")
slash := strings.Index(u, "/")
if colon >= 0 && (slash < 0 || colon < slash) {
// First path segment has a colon, assumed that it's a
// scheme-less URL. Append an empty scheme on top to
// satisfy RFC 3986 §3.3, and `net/url.Parse()`.
//
// In addition, replace the first colon with a slash since
// otherwise the colon looks like it's introducing a port
// number.
return fmt.Sprintf("//%s", strings.Replace(u, ":", "/", 1)), true
}
return u, true
}
var (
// supportedSchemes is the list of URL schemes the `lfsapi` package
// supports.
supportedSchemes = []string{"ssh", "http", "https"}
)
// hasScheme returns whether or not a given string (taken to represent a RFC
// 3986 URL) has a scheme that is supported by the `lfsapi` package.
func hasScheme(what string) bool {
for _, scheme := range supportedSchemes {
if strings.HasPrefix(what, fmt.Sprintf("%s://", scheme)) {
return true
}
}
return false
}
func requestHasAuth(req *http.Request) bool {
// The "Authorization" string constant is safe, since we assume that all
// request headers have been canonicalized.
if len(req.Header.Get("Authorization")) > 0 {
return true
}
return len(req.URL.Query().Get("token")) > 0
}
func setRequestAuthFromURL(req *http.Request, u *url.URL) bool {
if u.User == nil {
return false
}
if pass, ok := u.User.Password(); ok {
fmt.Fprintln(os.Stderr, "warning: current Git remote contains credentials")
setRequestAuth(req, u.User.Username(), pass)
return true
}
return false
}
func setRequestAuth(req *http.Request, user, pass string) {
if len(user) == 0 && len(pass) == 0 {
return
}
token := fmt.Sprintf("%s:%s", user, pass)
auth := "Basic " + strings.TrimSpace(base64.StdEncoding.EncodeToString([]byte(token)))
req.Header.Set("Authorization", auth)
}
func getReqOperation(req *http.Request) string {
operation := "download"
if req.Method == "POST" || req.Method == "PUT" {
operation = "upload"
}
return operation
}
var (
authenticateHeaders = []string{"Lfs-Authenticate", "Www-Authenticate"}
)
func getAuthAccess(res *http.Response) creds.AccessMode {
for _, headerName := range authenticateHeaders {
for _, auth := range res.Header[headerName] {
pieces := strings.SplitN(strings.ToLower(auth), " ", 2)
if len(pieces) == 0 {
continue
}
switch creds.AccessMode(pieces[0]) {
case creds.NegotiateAccess:
return creds.AccessMode(pieces[0])
}
}
}
return creds.BasicAccess
}