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/claims.go

@@ -0,0 +1,134 @@
+package jwt
+
+import (
+	"crypto/subtle"
+	"fmt"
+	"time"
+)
+
+// For a type to be a Claims object, it must just have a Valid method that determines
+// if the token is invalid for any supported reason
+type Claims interface {
+	Valid() error
+}
+
+// Structured version of Claims Section, as referenced at
+// https://tools.ietf.org/html/rfc7519#section-4.1
+// See examples for how to use this with your own claim types
+type StandardClaims struct {
+	Audience  string `json:"aud,omitempty"`
+	ExpiresAt int64  `json:"exp,omitempty"`
+	Id        string `json:"jti,omitempty"`
+	IssuedAt  int64  `json:"iat,omitempty"`
+	Issuer    string `json:"iss,omitempty"`
+	NotBefore int64  `json:"nbf,omitempty"`
+	Subject   string `json:"sub,omitempty"`
+}
+
+// Validates time based claims "exp, iat, nbf".
+// There is no accounting for clock skew.
+// As well, if any of the above claims are not in the token, it will still
+// be considered a valid claim.
+func (c StandardClaims) Valid() error {
+	vErr := new(ValidationError)
+	now := TimeFunc().Unix()
+
+	// The claims below are optional, by default, so if they are set to the
+	// default value in Go, let's not fail the verification for them.
+	if c.VerifyExpiresAt(now, false) == false {
+		delta := time.Unix(now, 0).Sub(time.Unix(c.ExpiresAt, 0))
+		vErr.Inner = fmt.Errorf("token is expired by %v", delta)
+		vErr.Errors |= ValidationErrorExpired
+	}
+
+	if c.VerifyIssuedAt(now, false) == false {
+		vErr.Inner = fmt.Errorf("Token used before issued")
+		vErr.Errors |= ValidationErrorIssuedAt
+	}
+
+	if c.VerifyNotBefore(now, false) == false {
+		vErr.Inner = fmt.Errorf("token is not valid yet")
+		vErr.Errors |= ValidationErrorNotValidYet
+	}
+
+	if vErr.valid() {
+		return nil
+	}
+
+	return vErr
+}
+
+// Compares the aud claim against cmp.
+// If required is false, this method will return true if the value matches or is unset
+func (c *StandardClaims) VerifyAudience(cmp string, req bool) bool {
+	return verifyAud(c.Audience, cmp, req)
+}
+
+// Compares the exp claim against cmp.
+// If required is false, this method will return true if the value matches or is unset
+func (c *StandardClaims) VerifyExpiresAt(cmp int64, req bool) bool {
+	return verifyExp(c.ExpiresAt, cmp, req)
+}
+
+// Compares the iat claim against cmp.
+// If required is false, this method will return true if the value matches or is unset
+func (c *StandardClaims) VerifyIssuedAt(cmp int64, req bool) bool {
+	return verifyIat(c.IssuedAt, cmp, req)
+}
+
+// Compares the iss claim against cmp.
+// If required is false, this method will return true if the value matches or is unset
+func (c *StandardClaims) VerifyIssuer(cmp string, req bool) bool {
+	return verifyIss(c.Issuer, cmp, req)
+}
+
+// Compares the nbf claim against cmp.
+// If required is false, this method will return true if the value matches or is unset
+func (c *StandardClaims) VerifyNotBefore(cmp int64, req bool) bool {
+	return verifyNbf(c.NotBefore, cmp, req)
+}
+
+// ----- helpers
+
+func verifyAud(aud string, cmp string, required bool) bool {
+	if aud == "" {
+		return !required
+	}
+	if subtle.ConstantTimeCompare([]byte(aud), []byte(cmp)) != 0 {
+		return true
+	} else {
+		return false
+	}
+}
+
+func verifyExp(exp int64, now int64, required bool) bool {
+	if exp == 0 {
+		return !required
+	}
+	return now <= exp
+}
+
+func verifyIat(iat int64, now int64, required bool) bool {
+	if iat == 0 {
+		return !required
+	}
+	return now >= iat
+}
+
+func verifyIss(iss string, cmp string, required bool) bool {
+	if iss == "" {
+		return !required
+	}
+	if subtle.ConstantTimeCompare([]byte(iss), []byte(cmp)) != 0 {
+		return true
+	} else {
+		return false
+	}
+}
+
+func verifyNbf(nbf int64, now int64, required bool) bool {
+	if nbf == 0 {
+		return !required
+	}
+	return now >= nbf
+}