[SERVER] iscsi: Reply OK to any task management function

Since we process everything sequentially, by the time we receive any
task management function, the task referenced in the request has already
been rejected (or processed), so we just reply OK for now, so the SNs
don't get messed up.

2 files changed, 235 insertions, 1 deletions

diff --git a/src/server/iscsi.c b/src/server/iscsi.c
index b0b171e..892172e 100644
--- a/src/server/iscsi.c
+++ b/src/server/iscsi.c
@@ -109,6 +109,8 @@ static iscsi_bhs_packet *iscsi_connection_pdu_resize(iscsi_pdu *pdu, const uint
 
 static bool iscsi_connection_pdu_write(iscsi_connection *conn, iscsi_pdu *pdu);
 
+static int iscsi_connection_handle_reject(iscsi_connection *conn, iscsi_pdu *pdu, int reason_code);
+
 
 /**
  * @brief Copies a string with additional padding character to fill in a specified size.
@@ -3067,6 +3069,38 @@ static int iscsi_connection_handle_logout_req(iscsi_connection *conn, iscsi_pdu
 }
 
 /**
+ * @brief Handles an iSCSI task management function request and generates an appropriate response.
+ *
+ * This function processes an incoming iSCSI task management function request PDU,
+ * constructs a corresponding response PDU, and sends it back to the initiator.
+ *
+ * @param[in] conn Pointer to the iSCSI connection structure. Must not be NULL.
+ * This represents the connection for which the request is being handled.
+ * @param[in] request_pdu Pointer to the incoming iSCSI task management function
+ * request PDU. Must not be NULL.
+ *
+ * @return 0 on successful PDU write, or -1 on failure.
+ */
+static int iscsi_connection_handle_task_func_req(iscsi_connection *conn, iscsi_pdu *request_pdu)
+{
+	iscsi_pdu CLEANUP_PDU response_pdu;
+	if ( !iscsi_connection_pdu_init( &response_pdu, 0, false ) )
+		return ISCSI_CONNECT_PDU_READ_ERR_FATAL;
+	iscsi_task_mgmt_func_response_packet *mgmt_resp = (iscsi_task_mgmt_func_response_packet *) response_pdu.bhs_pkt;
+	iscsi_task_mgmt_func_req_packet *mgmt_req = (iscsi_task_mgmt_func_req_packet *) request_pdu->bhs_pkt;
+
+	mgmt_resp->opcode        = ISCSI_OPCODE_SERVER_TASK_FUNC_RES;
+	mgmt_resp->response      = ISCSI_TASK_MGMT_FUNC_RESPONSE_FUNC_COMPLETE;
+	mgmt_resp->flags         = 0x80;
+	mgmt_resp->init_task_tag = mgmt_req->init_task_tag; // Copying over doesn't change endianess.
+	iscsi_put_be32( (uint8_t *) &mgmt_resp->stat_sn, conn->stat_sn++ );
+	iscsi_put_be32( (uint8_t *) &mgmt_resp->exp_cmd_sn, conn->session->exp_cmd_sn );
+	iscsi_put_be32( (uint8_t *) &mgmt_resp->max_cmd_sn, conn->session->max_cmd_sn );
+
+	return iscsi_connection_pdu_write( conn, &response_pdu ) ? 0 : -1;
+}
+
+/**
  * @brief Handles an incoming iSCSI payload data NOP-Out request PDU.
  *
  * This function handles NOP-Out request payload
@@ -3624,7 +3658,8 @@ static int iscsi_connection_pdu_handle(iscsi_connection *conn, iscsi_pdu *reques
 				break;
 			}
 			case ISCSI_OPCODE_CLIENT_TASK_FUNC_REQ : {
-				// TODO: Send OK if a task is requested to be cancelled
+				rc = iscsi_connection_handle_task_func_req( conn, request_pdu );
+
 				break;
 			}
 			default : {
diff --git a/src/server/iscsi.h b/src/server/iscsi.h
index ff33acd..a806530 100644
--- a/src/server/iscsi.h
+++ b/src/server/iscsi.h
@@ -3624,6 +3624,205 @@ typedef struct __attribute__((packed)) iscsi_scsi_response_packet {
 	uint32_t res_cnt;
 } iscsi_scsi_response_packet;
 
+
+/**
+ * @brief iSCSI Task Management Function Request packet data.
+ *
+ * This structure is used to explicity control the execution of one
+ * or more tasks (iSCSI and SCSI).
+ */
+typedef struct __attribute__((packed)) iscsi_task_mgmt_func_req_packet {
+    /// Always 2 according to iSCSI specification.
+    uint8_t opcode;
+
+    /**
+     * @brief Function.
+     *
+     * The task management functions provide an initiator with a way to
+     * explicitly control the execution of one or more tasks (SCSI and iSCSI
+     * tasks). The task management function codes are listed below. For a
+     * more detailed description of SCSI task management, see SAM2.
+     */
+    int8_t func;
+
+    /// Reserved fot future usage, always MUST be 0.
+    uint16_t reserved;
+
+    /// TotalAHSLength (MUST be 0 for this PDU).
+    uint8_t total_ahs_len;
+
+    /// DataSegmentLength (MUST be 0 for this PDU).
+    uint8_t ds_len[3];
+
+    /**
+     * @brief Logical Unit Number (LUN) or Reserved.
+     *
+     * This field is required for functions that address a specific LU
+     * (ABORT TASK, CLEAR TASK SET, ABORT TASK SET, CLEAR ACA, LOGICAL UNIT
+     * RESET) and is reserved in all others
+     */
+    uint64_t lun;
+
+    /**
+     * @brief Initiator Task Tag (ITT).
+     *
+     * This is the Initiator Task Tag of the task to be aborted for the
+     * ABORT TASK function or reassigned for the TASK REASSIGN function.
+     * For all the other functions, this field MUST be set to the reserved
+     * value 0xFFFFFFFF.
+     */
+    uint32_t init_task_tag;
+
+    /// Referenced task tag or 0xFFFFFFFF.
+    uint32_t ref_task_tag;
+
+    /// CmdSN.
+    uint32_t cmd_sn;
+
+    /// ExpStatSN
+    uint32_t exp_stat_sn;
+
+    /**
+     * @brief RefCmdSN or Reserved.
+     *
+     * If an ABORT TASK is issued for a task created by an immediate
+     * command, then the RefCmdSN MUST be that of the task management
+     * request itself (i.e., the CmdSN and RefCmdSN are equal).\n
+     * For an ABORT TASK of a task created by a non-immediate command, the
+     * RefCmdSN MUST be set to the CmdSN of the task identified by the
+     * Referenced Task Tag field. Targets must use this field when the task
+     * identified by the Referenced Task Tag field is not with the target.
+     * Otherwise, this field is reserved.
+     */
+    uint32_t ref_cmd_sn;
+
+    /**
+     * @brief ExpDataSN or Reserved.
+     *
+     * For recovery purposes, the iSCSI target and initiator maintain a data
+     * acknowledgment reference number - the first input DataSN number
+     * unacknowledged by the initiator. When issuing a new command, this
+     * number is set to 0. If the function is TASK REASSIGN, which
+     * establishes a new connection allegiance for a previously issued read
+     * or bidirectional command, the ExpDataSN will contain an updated data
+     * acknowledgment reference number or the value 0; the latter indicates
+     * that the data acknowledgment reference number is unchanged. The
+     * initiator MUST discard any data PDUs from the previous execution that
+     * it did not acknowledge, and the target MUST transmit all Data-In PDUs
+     * (if any) starting with the data acknowledgment reference number. The
+     * number of retransmitted PDUs may or may not be the same as the
+     * original transmission, depending on if there was a change in
+     * MaxRecvDataSegmentLength in the reassignment. The target MAY also
+     * send no more Data-In PDUs if all data has been acknowledged.
+     * The value of ExpDataSN MUST be 0 or higher than the DataSN of the
+     * last acknowledged Data-In PDU, but not larger than DataSN + 1 of the
+     * last Data-IN PDU sent by the target. Any other value MUST be ignored
+     * by the target.
+     * For other functions, this field is reserved
+     */
+    uint32_t exp_data_sn;
+
+    /// Reserved for future usage, always MUST be 0.
+    uint64_t reserved2;
+} iscsi_task_mgmt_func_req_packet;
+
+
+/// Task management function response: Function complete.
+#define ISCSI_TASK_MGMT_FUNC_RESPONSE_FUNC_COMPLETE               0x00
+
+/**
+ * @brief iSCSI Task Management Function Response packet data.
+ *
+ * For the functions ABORT TASK, ABORT TASK SET, CLEAR ACA, CLEAR TASK
+ * SET, LOGICAL UNIT RESET, TARGET COLD RESET, TARGET WARM RESET, and
+ * TASK REASSIGN, the target performs the requested task management
+ * function and sends a task management response back to the initiator.
+ * For TASK REASSIGN, the new connection allegiance MUST ONLY become
+ * effective at the target after the target issues the task management
+ * response.
+ */
+typedef struct __attribute__((packed)) iscsi_task_mgmt_func_response_packet {
+    /// Always 0x22 according to specification.
+    uint8_t opcode;
+
+    /// Reserved for future usage (always MUST be 0x80 for now).
+    uint8_t flags;
+
+    /**
+     * @brief Function response.
+     *
+     * For the TARGET COLD RESET and TARGET WARM RESET functions, the target
+     * cancels all pending operations across all LUs known to the issuing
+     * initiator. For the TARGET COLD RESET function, the target MUST then
+     * close all of its TCP connections to all initiators (terminates all
+     * sessions).\n
+     * The mapping of the response code into a SCSI service response code
+     * value, if needed, is outside the scope of this document. However, in
+     * symbolic terms, Response values 0 and 1 map to the SCSI service
+     * response of FUNCTION COMPLETE. Response value 2 maps to the SCSI
+     * service response of INCORRECT LOGICAL UNIT NUMBER. All other
+     * Response values map to the SCSI service response of FUNCTION
+     * REJECTED. If a Task Management Function Response PDU does not arrive
+     * before the session is terminated, the SCSI service response is
+     * SERVICE DELIVERY OR TARGET FAILURE.\n
+     * The response to ABORT TASK SET and CLEAR TASK SET MUST only be issued
+     * by the target after all of the commands affected have been received
+     * by the target, the corresponding task management functions have been
+     * executed by the SCSI target, and the delivery of all responses
+     * delivered until the task management function completion has been
+     * confirmed (acknowledged through the ExpStatSN) by the initiator on
+     * all connections of this session.\n
+     * For the ABORT TASK function,\n
+     * -# if the Referenced Task Tag identifies a valid task leading to a
+     *    successful termination, then targets must return the "Function
+     *    complete" response.
+     * -# if the Referenced Task Tag does not identify an existing task
+     *    but the CmdSN indicated by the RefCmdSN field in the Task
+     *    Management Function Request is within the valid CmdSN window
+     *    and less than the CmdSN of the Task Management Function Request
+     *    itself, then targets must consider the CmdSN as received and
+     *    return the "Function complete" response.
+     * -# if the Referenced Task Tag does not identify an existing task
+     *    and the CmdSN indicated by the RefCmdSN field in the Task
+     *    Management Function Request is outside the valid CmdSN window,
+     *    then targets must return the "Task does not exist" response
+     */
+    uint8_t response;
+
+    /// Reserved for future usage, always MUST be 0.
+    uint8_t reserved;
+
+    /// TotalAHSLength (MUST be 0 for this PDU).
+    uint8_t total_ahs_len;
+
+    /// DataSegmentLength (MUST be 0 for this PDU).
+    uint8_t ds_len[3];
+
+    /// Reserved for future usage, always MUST be 0.
+    uint64_t reserved2;
+
+    /// Initiator Task Tag (ITT).
+    uint32_t init_task_tag;
+
+    /// Reserved for future usage, always MUST be 0.
+    uint32_t reserved3;
+
+    /// StatSN.
+    uint32_t stat_sn;
+
+    /// ExpCmdSN.
+    uint32_t exp_cmd_sn;
+
+    /// MaxCmdSN.
+    uint32_t max_cmd_sn;
+
+    /// Reserved for future usage, always MUST be 0.
+    uint32_t reserved4;
+
+    /// Reserved for future usage, always MUST be 0.
+    uint64_t reserved5;
+} iscsi_task_mgmt_func_response_packet;
+
 /// SCSI data out / in flags: Immediately process transfer.
 #define ISCSI_SCSI_DATA_OUT_DATA_IN_FLAGS_IMMEDIATE (1 << 7)