From a81eacc0b16552fe63ea1536cffec547c6e3db53 Mon Sep 17 00:00:00 2001
From: lishiao <1447175116@qq.com>
Date: Tue, 17 Jun 2025 11:57:38 +0800
Subject: [PATCH] iscsi: compute Data Digest for out_data segments

---
 include/iscsi-private.h |  2 ++
 lib/socket.c            | 24 ++++++++++++++++++++----
 2 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/include/iscsi-private.h b/include/iscsi-private.h
index 1fce36a..69c9e3b 100644
--- a/include/iscsi-private.h
+++ b/include/iscsi-private.h
@@ -20,6 +20,7 @@
 #include <stdint.h>
 #include <time.h>
 #include <unistd.h>
+#include <stdbool.h>
 
 #if defined(_WIN32)
 #include <basetsd.h>
@@ -316,6 +317,7 @@ struct iscsi_pdu {
 	uint32_t expxferlen;
 
 	uint32_t calculated_data_digest;
+	bool outdata_digest_computed;
 };
 
 struct iscsi_pdu *iscsi_allocate_pdu(struct iscsi_context *iscsi,
diff --git a/lib/socket.c b/lib/socket.c
index 0b45663..9100064 100644
--- a/lib/socket.c
+++ b/lib/socket.c
@@ -839,13 +839,12 @@ static int iscsi_pdu_update_headerdigest(struct iscsi_context *iscsi, struct isc
 static int
 iscsi_write_to_socket(struct iscsi_context *iscsi)
 {
-	ssize_t count;
+	ssize_t count, data_segment_len;
 	size_t total;
 	struct iscsi_pdu *pdu;
 	static char padding_buf[3];
 	int socket_flags = 0;
-	bool do_data_digest = (iscsi->data_digest != ISCSI_DATA_DIGEST_NONE);
-
+	bool do_data_digest = (iscsi->data_digest != ISCSI_DATA_DIGEST_NONE), execute_data_digest;
 #ifdef MSG_NOSIGNAL
 	socket_flags |= MSG_NOSIGNAL;
 #elif SO_NOSIGPIPE
@@ -935,6 +934,23 @@ iscsi_write_to_socket(struct iscsi_context *iscsi)
 			return 0;
 		}
 
+		data_segment_len = iscsi_get_pdu_data_size(pdu->outdata.data);
+		if (do_data_digest &&
+			data_segment_len &&
+			!pdu->payload_len)
+			execute_data_digest = true;
+		else
+			execute_data_digest = false;
+
+		if (execute_data_digest && !pdu->outdata_digest_computed)
+		{
+			uint8_t ahslen = pdu->outdata.data[4];
+			uint8_t head_len = iscsi->header_digest != ISCSI_HEADER_DIGEST_NONE ? 52 : 48;
+			uint32_t offset = head_len + ahslen * 4;
+			pdu->calculated_data_digest = crc32c_chain(pdu->calculated_data_digest, pdu->outdata.data + offset, pdu->outdata.size - offset);
+			pdu->outdata_digest_computed = true;
+		}
+
 		/* Write any iovectors that might have been passed to us */
 		while (pdu->payload_written < pdu->payload_len) {
 			struct scsi_iovector* iovector_out;
@@ -991,7 +1007,7 @@ iscsi_write_to_socket(struct iscsi_context *iscsi)
 		 * 1. DataDigest has been negociated, and
 		 * 2. We have actually written some data
 		 */
-		if (do_data_digest && pdu->payload_written) {
+		if (execute_data_digest || (do_data_digest && pdu->payload_written)) {
 			uint32_t data_digest = crc32c_chain_done(pdu->calculated_data_digest);
 			char data_digest_buf[ISCSI_DIGEST_SIZE];