Git LFS support v2 (#122)

* Import github.com/git-lfs/lfs-test-server as lfs module base

Imported commit is 3968aac269a77b73924649b9412ae03f7ccd3198

Removed:

Dockerfile CONTRIBUTING.md mgmt* script/ vendor/ kvlogger.go
.dockerignore .gitignore README.md

* Remove config, add JWT support from github.com/mgit-at/lfs-test-server

Imported commit f0cdcc5a01599c5a955dc1bbf683bb4acecdba83

* Add LFS settings

* Add LFS meta object model

* Add LFS routes and initialization

* Import github.com/dgrijalva/jwt-go into vendor/

* Adapt LFS module: handlers, routing, meta store

* Move LFS routes to /user/repo/info/lfs/*

* Add request header checks to LFS BatchHandler / PostHandler

* Implement LFS basic authentication

* Rework JWT secret generation / load

* Implement LFS SSH token authentication with JWT

Specification: https://github.com/github/git-lfs/tree/master/docs/api

* Integrate LFS settings into install process

* Remove LFS objects when repository is deleted

Only removes objects from content store when deleted repo is the only
referencing repository

* Make LFS module stateless

Fixes bug where LFS would not work after installation without
restarting Gitea

* Change 500 'Internal Server Error' to 400 'Bad Request'

* Change sql query to xorm call

* Remove unneeded type from LFS module

* Change internal imports to code.gitea.io/gitea/

* Add Gitea authors copyright

* Change basic auth realm to "gitea-lfs"

* Add unique indexes to LFS model

* Use xorm count function in LFS check on repository delete

* Return io.ReadCloser from content store and close after usage

* Add LFS info to runWeb()

* Export LFS content store base path

* LFS file download from UI

* Work around git-lfs client issue with unauthenticated requests

Returning a dummy Authorization header for unauthenticated requests
lets git-lfs client skip asking for auth credentials
See: https://github.com/github/git-lfs/issues/1088

* Fix unauthenticated UI downloads from public repositories

* Authentication check order, Finish LFS file view logic

* Ignore LFS hooks if installed for current OS user

Fixes Gitea UI actions for repositories tracking LFS files.
Checks for minimum needed git version by parsing the semantic version
string.

* Hide LFS metafile diff from commit view, marking as binary

* Show LFS notice if file in commit view is tracked

* Add notbefore/nbf JWT claim

* Correct lint suggestions - comments for structs and functions

- Add comments to LFS model
- Function comment for GetRandomBytesAsBase64
- LFS server function comments and lint variable suggestion

* Move secret generation code out of conditional

Ensures no LFS code may run with an empty secret

* Do not hand out JWT tokens if LFS server support is disabled

vendor/github.com/dgrijalva/jwt-go/errors.go

@@ -0,0 +1,59 @@
+package jwt
+
+import (
+	"errors"
+)
+
+// Error constants
+var (
+	ErrInvalidKey      = errors.New("key is invalid")
+	ErrInvalidKeyType  = errors.New("key is of invalid type")
+	ErrHashUnavailable = errors.New("the requested hash function is unavailable")
+)
+
+// The errors that might occur when parsing and validating a token
+const (
+	ValidationErrorMalformed        uint32 = 1 << iota // Token is malformed
+	ValidationErrorUnverifiable                        // Token could not be verified because of signing problems
+	ValidationErrorSignatureInvalid                    // Signature validation failed
+
+	// Standard Claim validation errors
+	ValidationErrorAudience      // AUD validation failed
+	ValidationErrorExpired       // EXP validation failed
+	ValidationErrorIssuedAt      // IAT validation failed
+	ValidationErrorIssuer        // ISS validation failed
+	ValidationErrorNotValidYet   // NBF validation failed
+	ValidationErrorId            // JTI validation failed
+	ValidationErrorClaimsInvalid // Generic claims validation error
+)
+
+// Helper for constructing a ValidationError with a string error message
+func NewValidationError(errorText string, errorFlags uint32) *ValidationError {
+	return &ValidationError{
+		text:   errorText,
+		Errors: errorFlags,
+	}
+}
+
+// The error from Parse if token is not valid
+type ValidationError struct {
+	Inner  error  // stores the error returned by external dependencies, i.e.: KeyFunc
+	Errors uint32 // bitfield.  see ValidationError... constants
+	text   string // errors that do not have a valid error just have text
+}
+
+// Validation error is an error type
+func (e ValidationError) Error() string {
+	if e.Inner != nil {
+		return e.Inner.Error()
+	} else if e.text != "" {
+		return e.text
+	} else {
+		return "token is invalid"
+	}
+}
+
+// No errors
+func (e *ValidationError) valid() bool {
+	return e.Errors == 0
+}