[Filebeat][httpjson] httpjson oauth2 authentication mechanism for sal…

…esforce events (#29087)

* Add grant-type: passoword in httpjson oauth2

* refactor code and add new properties tests in config_test.go

* Add grant_type: password in oAuth2ProviderDefault

* Update CHANGELOG.next.asciidoc

* update input-httpjson.asciidoc with new extended httpjson authentication method

* add comment for authstyleparam variable

* update user dummy value in the doc

* Update input-httpjson.asciidoc - provider should be default only for user-passowrd method

* refactor code and add new properties tests in config_test.go

* Add grant_type: password in oAuth2ProviderDefault

Co-authored-by: Sunny Chaudhari <sunny.chaudhari@elastic.co>

CHANGELOG.next.asciidoc

@@ -350,6 +350,7 @@ https://github.com/elastic/beats/compare/v7.0.0-alpha2...master[Check the HEAD d
 - Add support in aws-s3 input for custom script parsing of s3 notifications. {pull}28946[28946]
 - Improve error handling in aws-s3 input for malformed s3 notifications. {issue}28828[28828] {pull}28946[28946]
 - Add support for parsers on journald input {pull}29070[29070]
+- Add support in httpjson input for oAuth2ProviderDefault of password grant_type. {pull}29087[29087]
 
 *Heartbeat*
 

x-pack/filebeat/docs/inputs/input-httpjson.asciidoc

@@ -85,6 +85,19 @@ filebeat.inputs:
   request.url: http://localhost
 ----
 
+["source","yaml",subs="attributes"]
+----
+filebeat.inputs:
+- type: httpjson
+  auth.oauth2:
+    client.id: 12345678901234567890abcdef
+    client.secret: abcdef12345678901234567890
+    token_url: http://localhost/oauth2/token
+    user: user@domain.tld
+    password: P@$$W0₹D
+  request.url: http://localhost
+----
+
 [[input-state]]
 ==== Input state
 
@@ -265,6 +278,22 @@ except if using `google` as provider. Required for providers: `default`, `azure`
 The client secret used as part of the authentication flow. It is always required
 except if using `google` as provider. Required for providers: `default`, `azure`.
 
+[float]
+==== `auth.oauth2.user`
+
+The user used as part of the authentication flow. It is required for authentication
+ - grant type password. It is only available for provider `default`.
+
+[float]
+==== `auth.oauth2.password`
+
+The password used as part of the authentication flow. It is required for authentication
+ - grant type password. It is only available for provider `default`.
+
+NOTE: user and password are required for grant_type password. If user and 
+password is not used then it will automatically use the `token_url` and 
+`client credential` method.
+
 [float]
 ==== `auth.oauth2.scopes`
 

x-pack/filebeat/input/httpjson/config_auth.go

@@ -22,6 +22,9 @@ import (
 	"github.com/elastic/beats/v7/libbeat/common"
 )
 
+// authStyleInParams sends the "client_id" and "client_secret" in the POST body as application/x-www-form-urlencoded parameters.
+const authStyleInParams = 1
+
 type authConfig struct {
 	Basic  *basicAuthConfig `config:"basic"`
 	OAuth2 *oAuth2Config    `config:"oauth2"`
@@ -83,9 +86,11 @@ type oAuth2Config struct {
 	ClientID       string              `config:"client.id"`
 	ClientSecret   string              `config:"client.secret"`
 	EndpointParams map[string][]string `config:"endpoint_params"`
+	Password       string              `config:"password"`
 	Provider       oAuth2Provider      `config:"provider"`
 	Scopes         []string            `config:"scopes"`
 	TokenURL       string              `config:"token_url"`
+	User           string              `config:"user"`
 
 	// google specific
 	GoogleCredentialsFile  string          `config:"google.credentials_file"`
@@ -103,20 +108,43 @@ func (o *oAuth2Config) isEnabled() bool {
 	return o != nil && (o.Enabled == nil || *o.Enabled)
 }
 
+// clientCredentialsGrant creates http client from token_url and client credentials
+func (o *oAuth2Config) clientCredentialsGrant(ctx context.Context, client *http.Client) *http.Client {
+	creds := clientcredentials.Config{
+		ClientID:       o.ClientID,
+		ClientSecret:   o.ClientSecret,
+		TokenURL:       o.getTokenURL(),
+		Scopes:         o.Scopes,
+		EndpointParams: o.getEndpointParams(),
+	}
+	return creds.Client(ctx)
+}
+
 // Client wraps the given http.Client and returns a new one that will use the oauth authentication.
 func (o *oAuth2Config) client(ctx context.Context, client *http.Client) (*http.Client, error) {
 	ctx = context.WithValue(ctx, oauth2.HTTPClient, client)
 
 	switch o.getProvider() {
-	case oAuth2ProviderAzure, oAuth2ProviderDefault:
-		creds := clientcredentials.Config{
-			ClientID:       o.ClientID,
-			ClientSecret:   o.ClientSecret,
-			TokenURL:       o.getTokenURL(),
-			Scopes:         o.Scopes,
-			EndpointParams: o.getEndpointParams(),
+	case oAuth2ProviderDefault:
+		if o.User != "" || o.Password != "" {
+			conf := &oauth2.Config{
+				ClientID:     o.ClientID,
+				ClientSecret: o.ClientSecret,
+				Endpoint: oauth2.Endpoint{
+					TokenURL:  o.TokenURL,
+					AuthStyle: authStyleInParams,
+				},
+			}
+			token, err := conf.PasswordCredentialsToken(ctx, o.User, o.Password)
+			if err != nil {
+				return nil, fmt.Errorf("oauth2 client: error loading credentials using user and password: %w", err)
+			}
+			return conf.Client(ctx, token), nil
+		} else {
+			return o.clientCredentialsGrant(ctx, client), nil
 		}
-		return creds.Client(ctx), nil
+	case oAuth2ProviderAzure:
+		return o.clientCredentialsGrant(ctx, client), nil
 	case oAuth2ProviderGoogle:
 		if o.GoogleJWTFile != "" {
 			cfg, err := google.JWTConfigFromJSON(o.GoogleCredentialsJSON, o.Scopes...)
@@ -184,6 +212,9 @@ func (o *oAuth2Config) Validate() error {
 		if o.TokenURL == "" || o.ClientID == "" || o.ClientSecret == "" {
 			return errors.New("both token_url and client credentials must be provided")
 		}
+		if (o.User != "" && o.Password == "") || (o.User == "" && o.Password != "") {
+			return errors.New("both user and password credentials must be provided")
+		}
 	default:
 		return fmt.Errorf("unknown provider %q", o.getProvider())
 	}

x-pack/filebeat/input/httpjson/config_test.go

@@ -152,6 +152,48 @@ func TestConfigOauth2Validation(t *testing.T) {
 				"auth.oauth2": map[string]interface{}{},
 			},
 		},
+		{
+			name: "if user and password is set oauth2 must use user-password authentication",
+			input: map[string]interface{}{
+				"auth.oauth2": map[string]interface{}{
+					"user":      "a_client_user",
+					"password":  "a_client_password",
+					"token_url": "localhost",
+					"client": map[string]interface{}{
+						"id":     "a_client_id",
+						"secret": "a_client_secret",
+					},
+				},
+			},
+		},
+		{
+			name:        "if user is set password credentials must be set for user-password authentication",
+			expectedErr: "both user and password credentials must be provided accessing 'auth.oauth2'",
+			input: map[string]interface{}{
+				"auth.oauth2": map[string]interface{}{
+					"user":      "a_client_user",
+					"token_url": "localhost",
+					"client": map[string]interface{}{
+						"id":     "a_client_id",
+						"secret": "a_client_secret",
+					},
+				},
+			},
+		},
+		{
+			name:        "if password is set user credentials must be set for user-password authentication",
+			expectedErr: "both user and password credentials must be provided accessing 'auth.oauth2'",
+			input: map[string]interface{}{
+				"auth.oauth2": map[string]interface{}{
+					"password":  "a_client_password",
+					"token_url": "localhost",
+					"client": map[string]interface{}{
+						"id":     "a_client_id",
+						"secret": "a_client_secret",
+					},
+				},
+			},
+		},
 		{
 			name:        "must fail with an unknown provider",
 			expectedErr: "unknown provider \"unknown\" accessing 'auth.oauth2'",