Support CORS headers to git smart http protocol (#5719)

Author: lunny

Diff for: custom/conf/app.ini.sample

@@ -31,6 +31,9 @@ PULL_REQUEST_QUEUE_LENGTH = 1000
 PREFERRED_LICENSES = Apache License 2.0,MIT License
 ; Disable the ability to interact with repositories using the HTTP protocol
 DISABLE_HTTP_GIT = false
+; Value for Access-Control-Allow-Origin header, default is not to present
+; WARNING: This maybe harmful to you website if you do not give it a right value.
+ACCESS_CONTROL_ALLOW_ORIGIN = 
 ; Force ssh:// clone url instead of scp-style uri when default SSH port is used
 USE_COMPAT_SSH_URI = false
 

Diff for: docs/content/doc/advanced/config-cheat-sheet.en-us.md

@@ -62,6 +62,9 @@ Values containing `#` or `;` must be quoted using `` ` `` or `"""`.
    HTTP protocol.
 - `USE_COMPAT_SSH_URI`: **false**: Force ssh:// clone url instead of scp-style uri when
    default SSH port is used.
+- `ACCESS_CONTROL_ALLOW_ORIGIN`: **\<empty\>**: Value for Access-Control-Allow-Origin header,
+   default is not to present. **WARNING**: This maybe harmful to you website if you do not
+   give it a right value.
 
 ### Repository - Pull Request (`repository.pull-request`)
 - `WORK_IN_PROGRESS_PREFIXES`: **WIP:,\[WIP\]**: List of prefixes used in Pull Request

Diff for: modules/setting/setting.go

@@ -201,15 +201,16 @@ var (
 
 	// Repository settings
 	Repository = struct {
-		AnsiCharset            string
-		ForcePrivate           bool
-		DefaultPrivate         string
-		MaxCreationLimit       int
-		MirrorQueueLength      int
-		PullRequestQueueLength int
-		PreferredLicenses      []string
-		DisableHTTPGit         bool
-		UseCompatSSHURI        bool
+		AnsiCharset              string
+		ForcePrivate             bool
+		DefaultPrivate           string
+		MaxCreationLimit         int
+		MirrorQueueLength        int
+		PullRequestQueueLength   int
+		PreferredLicenses        []string
+		DisableHTTPGit           bool
+		AccessControlAllowOrigin string
+		UseCompatSSHURI          bool
 
 		// Repository editor settings
 		Editor struct {
@@ -237,15 +238,16 @@ var (
 			WorkInProgressPrefixes []string
 		} `ini:"repository.pull-request"`
 	}{
-		AnsiCharset:            "",
-		ForcePrivate:           false,
-		DefaultPrivate:         RepoCreatingLastUserVisibility,
-		MaxCreationLimit:       -1,
-		MirrorQueueLength:      1000,
-		PullRequestQueueLength: 1000,
-		PreferredLicenses:      []string{"Apache License 2.0,MIT License"},
-		DisableHTTPGit:         false,
-		UseCompatSSHURI:        false,
+		AnsiCharset:              "",
+		ForcePrivate:             false,
+		DefaultPrivate:           RepoCreatingLastUserVisibility,
+		MaxCreationLimit:         -1,
+		MirrorQueueLength:        1000,
+		PullRequestQueueLength:   1000,
+		PreferredLicenses:        []string{"Apache License 2.0,MIT License"},
+		DisableHTTPGit:           false,
+		AccessControlAllowOrigin: "",
+		UseCompatSSHURI:          false,
 
 		// Repository editor settings
 		Editor: struct {

Diff for: routers/repo/http.go

@@ -27,6 +27,18 @@ import (
 
 // HTTP implmentation git smart HTTP protocol
 func HTTP(ctx *context.Context) {
+	if len(setting.Repository.AccessControlAllowOrigin) > 0 {
+		// Set CORS headers for browser-based git clients
+		ctx.Resp.Header().Set("Access-Control-Allow-Origin", setting.Repository.AccessControlAllowOrigin)
+		ctx.Resp.Header().Set("Access-Control-Allow-Headers", "Content-Type, Authorization, User-Agent")
+
+		// Handle preflight OPTIONS request
+		if ctx.Req.Method == "OPTIONS" {
+			ctx.Status(http.StatusOK)
+			return
+		}
+	}
+
 	username := ctx.Params(":username")
 	reponame := strings.TrimSuffix(ctx.Params(":reponame"), ".git")