diff --git a/COPYING b/COPYING
index dddde82..ac8d5bf 100644
--- a/COPYING
+++ b/COPYING
@@ -15,16 +15,8 @@ A copy of LGPL 2.1 is included in the file LICENCE-LGPL-2.1.txt but can also be
 This is the licence that applies to the libiscsi library and its use.
 
 
-src/ld_iscsi.c
-==============
-This LD_PRELOAD utility is licenced under GNU Lesser General Public License
-as published by the Free Software Foundation; either version 2.1 of the
-License, or (at your option) any later version.
-
-
-
-The src, examples and test-tool directories EXCEPT src/ld_iscsi.c
-=============================================================
+The src, examples and test-tool directories
+===========================================
 The utility and example applications using this library, i.e. the src and the
 examples directories, are licenced under the GNU General Public License
 as published by the Free Software Foundation; either version 2 of the
diff --git a/Makefile.am b/Makefile.am
index bd2ca58..abefb53 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -29,5 +29,5 @@ pkgconfig_DATA = libiscsi.pc
 iscsi_includedir = $(includedir)/iscsi
 dist_iscsi_include_HEADERS = include/iscsi.h include/scsi-lowlevel.h
 dist_noinst_HEADERS = include/iscsi-private.h include/md5.h include/slist.h \
-	              include/iser-private.h
+	              include/iser-private.h include/utils.h
 
diff --git a/README.md b/README.md
index f5d4f91..0886e58 100644
--- a/README.md
+++ b/README.md
@@ -46,6 +46,7 @@ Username and password for bidirectional CHAP authentication:
 target_user=<account>
 target_password=<password>
 header_digest=<crc32c|none>
+data_digest=<crc32c|none>
 Transport:
 iser
 
@@ -126,6 +127,15 @@ be overridden by an application by calling iscsi_set_header_digest() if the
 application wants to force a specific setting.
 
 
+Data Digest
+===========
+
+Libiscsi supports DataDigest.  By default, libiscsi will offer None so that
+Data digest will not be used, no matter what the target setting is.  This can
+be overridden by an application by calling iscsi_set_data_digest() if the
+application wants to force a specific setting.
+
+
 Patches
 =======
 
diff --git a/configure.ac b/configure.ac
index c81b916..13ae3bb 100644
--- a/configure.ac
+++ b/configure.ac
@@ -78,8 +78,43 @@ AM_CONDITIONAL([BUILD_EXAMPLES],
 
 AC_CONFIG_HEADERS([config.h])
 
-AC_CHECK_LIB([gcrypt], [gcry_control])
-AM_CONDITIONAL([HAVE_LIBGCRYPT], [test $ac_cv_lib_gcrypt_gcry_control = yes])
+AC_ARG_WITH([gnutls],
+	    [AS_HELP_STRING([--with-gnutls],
+			    [Use gnutls to compute MD5])],
+	    [WITH_GNUTLS=$withval],
+	    [WITH_GNUTLS=auto])
+
+AC_ARG_WITH([libgcrypt],
+	    [AS_HELP_STRING([--with-libgcrypt],
+			    [Use libgcrypt to compute MD5])],
+	    [WITH_LIBGCRYPT=$withval],
+	    [WITH_LIBGCRYPT=auto])
+
+if test "$WITH_GNUTLS" != no; then
+  AC_CHECK_LIB([gnutls], [gnutls_hash_init])
+  if test "$WITH_GNUTLS" = yes && test "$ac_cv_lib_gnutls_gnutls_hash_init" != yes; then
+    AC_MSG_ERROR([gnutls not found])
+  fi
+  WITH_GNUTLS=$ac_cv_lib_gnutls_gnutls_hash_init
+fi
+if test "$WITH_GNUTLS" = yes; then
+  WITH_LIBGCRYPT=no
+fi
+
+if test "$WITH_LIBGCRYPT" != no; then
+  AC_CHECK_LIB([gcrypt], [gcry_control])
+  if test "$WITH_LIBGCRYPT" = yes && test "$ac_cv_lib_gcrypt_gcry_control" != yes; then
+    AC_MSG_ERROR([libgcrypt not found])
+  fi
+  WITH_LIBGCRYPT=$ac_cv_lib_gcrypt_gcry_control
+fi
+
+NEED_MD5=no
+if test "$WITH_GNUTLS" = no && test "$WITH_LIBGCRYPT" = no; then
+  NEED_MD5=yes
+fi
+AM_CONDITIONAL([NEED_MD5],
+	       [expr "$NEED_MD5" : yes > /dev/null 2>&1])
 
 # For MinGW.
 AC_CHECK_LIB([ws2_32], [gethostbyname])
diff --git a/include/iscsi-private.h b/include/iscsi-private.h
index 82a328f..4a06658 100644
--- a/include/iscsi-private.h
+++ b/include/iscsi-private.h
@@ -61,6 +61,13 @@ struct iscsi_in_pdu {
 
 	long long data_pos;
 	unsigned char *data;
+
+	/*
+	 * Some data structures wrt Data Digest (if negociated)
+	 */
+	unsigned char data_digest_buf[ISCSI_DIGEST_SIZE];
+	int received_data_digest_bytes;
+	uint32_t calculated_data_digest;
 };
 void iscsi_free_iscsi_in_pdu(struct iscsi_context *iscsi, struct iscsi_in_pdu *in);
 
@@ -105,6 +112,8 @@ struct iscsi_context {
 	uint32_t statsn;
 	enum iscsi_header_digest want_header_digest;
 	enum iscsi_header_digest header_digest;
+	enum iscsi_data_digest want_data_digest;
+	enum iscsi_data_digest data_digest;
 
 	int fd;
 	int is_connected;
@@ -272,6 +281,8 @@ struct iscsi_pdu {
 	struct iscsi_scsi_cbdata scsi_cbdata;
 	time_t scsi_timeout;
 	uint32_t expxferlen;
+
+	uint32_t calculated_data_digest;
 };
 
 struct iscsi_pdu *iscsi_allocate_pdu(struct iscsi_context *iscsi,
@@ -293,6 +304,7 @@ void iscsi_pdu_set_ritt(struct iscsi_pdu *pdu, uint32_t ritt);
 void iscsi_pdu_set_datasn(struct iscsi_pdu *pdu, uint32_t datasn);
 void iscsi_pdu_set_bufferoffset(struct iscsi_pdu *pdu, uint32_t bufferoffset);
 void iscsi_cancel_pdus(struct iscsi_context *iscsi);
+void iscsi_cancel_lun_pdus(struct iscsi_context *iscsi, uint32_t lun);
 int iscsi_pdu_add_data(struct iscsi_context *iscsi, struct iscsi_pdu *pdu,
 		       const unsigned char *dptr, int dsize);
 int iscsi_queue_pdu(struct iscsi_context *iscsi, struct iscsi_pdu *pdu);
@@ -350,6 +362,9 @@ void* iscsi_szmalloc(struct iscsi_context *iscsi, size_t size);
 void iscsi_sfree(struct iscsi_context *iscsi, void* ptr);
 
 uint32_t crc32c(uint8_t *buf, int len);
+void crc32c_init(uint32_t *crc_ptr);
+uint32_t crc32c_chain(uint32_t crc, uint8_t *buf, int len);
+uint32_t crc32c_chain_done(uint32_t crc);
 
 struct scsi_task *iscsi_scsi_get_task_from_pdu(struct iscsi_pdu *pdu);
 
diff --git a/include/iscsi.h b/include/iscsi.h
index 8196f64..af557e7 100644
--- a/include/iscsi.h
+++ b/include/iscsi.h
@@ -335,6 +335,29 @@ enum iscsi_header_digest {
 EXTERN int iscsi_set_header_digest(struct iscsi_context *iscsi,
 			    enum iscsi_header_digest header_digest);
 
+/*
+ * Types of data digest we support. Default is NONE
+ */
+enum iscsi_data_digest {
+	ISCSI_DATA_DIGEST_NONE        = 0,
+	ISCSI_DATA_DIGEST_NONE_CRC32C = 1,
+	ISCSI_DATA_DIGEST_CRC32C_NONE = 2,
+	ISCSI_DATA_DIGEST_CRC32C      = 3,
+	ISCSI_DATA_DIGEST_LAST        = ISCSI_DATA_DIGEST_CRC32C
+};
+
+/*
+ * Set the desired data digest for a scsi context.
+ * Data digest can only be set/changed before the context
+ * is logged in to the target.
+ *
+ * Returns:
+ *  0: success
+ * <0: error
+ */
+EXTERN int iscsi_set_data_digest(struct iscsi_context *iscsi,
+			    enum iscsi_data_digest data_digest);
+
 /*
  * Specify the username and password to use for chap authentication
  */
diff --git a/lib/Makefile.am b/lib/Makefile.am
index b81fd3d..ba6aaee 100644
--- a/lib/Makefile.am
+++ b/lib/Makefile.am
@@ -12,7 +12,7 @@ if TARGET_OS_IS_WIN32
 libiscsipriv_la_SOURCES += ../win32/win32_compat.c
 endif
 
-if !HAVE_LIBGCRYPT
+if NEED_MD5
 libiscsipriv_la_SOURCES += md5.c
 endif
 
@@ -45,7 +45,7 @@ endif
 
 EXTRA_libiscsi_la_DEPENDENCIES = libiscsi.syms
 
-SOCURRENT=9
+SOCURRENT=10
 SOREVISON=0
 SOAGE=0
 libiscsi_la_LDFLAGS = \
diff --git a/lib/connect.c b/lib/connect.c
index 5234e46..1960ef2 100644
--- a/lib/connect.c
+++ b/lib/connect.c
@@ -431,6 +431,7 @@ static int reconnect(struct iscsi_context *iscsi, int force)
 	iscsi_set_targetname(tmp_iscsi, iscsi->target_name);
 
 	iscsi_set_header_digest(tmp_iscsi, iscsi->want_header_digest);
+	iscsi_set_data_digest(tmp_iscsi, iscsi->want_data_digest);
 
 	iscsi_set_initiator_username_pwd(tmp_iscsi, iscsi->user, iscsi->passwd);
 	iscsi_set_target_username_pwd(tmp_iscsi, iscsi->target_user, iscsi->target_passwd);
diff --git a/lib/crc32c.c b/lib/crc32c.c
index 10180ba..313cad0 100644
--- a/lib/crc32c.c
+++ b/lib/crc32c.c
@@ -118,3 +118,22 @@ uint32_t crc32c(uint8_t *buf, int len)
 	return crc^0xffffffff;
 }
 
+void crc32c_init(uint32_t *crc_ptr)
+{
+   if (crc_ptr)
+      *crc_ptr = 0xffffffff;
+}
+
+uint32_t crc32c_chain(uint32_t crc, uint8_t *buf, int len)
+{
+	while (len-- > 0) {
+		crc = (crc>>8) ^ crctable[(crc ^ (*buf++)) & 0xFF];
+	}
+	return crc;
+}
+
+uint32_t crc32c_chain_done(uint32_t crc)
+{
+	return crc^0xffffffff;
+}
+
diff --git a/lib/init.c b/lib/init.c
index 6bcc761..cb3baeb 100644
--- a/lib/init.c
+++ b/lib/init.c
@@ -244,6 +244,7 @@ iscsi_create_context(const char *initiator_name)
 	iscsi->want_immediate_data                    = ISCSI_IMMEDIATE_DATA_YES;
 	iscsi->use_immediate_data                     = ISCSI_IMMEDIATE_DATA_YES;
 	iscsi->want_header_digest                     = ISCSI_HEADER_DIGEST_NONE_CRC32C;
+	iscsi->want_data_digest                       = ISCSI_DATA_DIGEST_NONE;
 
 	iscsi->tcp_keepcnt=3;
 	iscsi->tcp_keepintvl=30;
@@ -492,6 +493,25 @@ iscsi_set_header_digest(struct iscsi_context *iscsi,
 	return 0;
 }
 
+int
+iscsi_set_data_digest(struct iscsi_context *iscsi,
+			enum iscsi_data_digest data_digest)
+{
+	if (iscsi->is_loggedin) {
+		iscsi_set_error(iscsi, "trying to set data digest while "
+				"logged in");
+		return -1;
+	}
+	if ((unsigned)data_digest > ISCSI_DATA_DIGEST_LAST) {
+		iscsi_set_error(iscsi, "invalid data digest value");
+		return -1;
+	}
+
+	iscsi->want_data_digest = data_digest;
+
+	return 0;
+}
+
 int
 iscsi_is_logged_in(struct iscsi_context *iscsi)
 {
@@ -602,19 +622,32 @@ iscsi_parse_url(struct iscsi_context *iscsi, const char *url, int full)
 			if (value != NULL) {
 				*value++ = 0;
 			}
-                        if (!strcmp(key, "header_digest")) {
-                                if (!strcmp(value, "crc32c")) {
-                                        iscsi_set_header_digest(
-                                            iscsi, ISCSI_HEADER_DIGEST_CRC32C);
-                                } else if (!strcmp(value, "none")) {
-                                        iscsi_set_header_digest(
-                                            iscsi, ISCSI_HEADER_DIGEST_NONE);
-                                } else {
-                                        iscsi_set_error(iscsi,
-                                            "Invalid URL argument for header_digest: %s", value);
-                                        return NULL;
-                                }
-                        }
+			if (!strcmp(key, "header_digest")) {
+				if (!strcmp(value, "crc32c")) {
+					iscsi_set_header_digest(
+						iscsi, ISCSI_HEADER_DIGEST_CRC32C);
+				} else if (!strcmp(value, "none")) {
+					iscsi_set_header_digest(
+						iscsi, ISCSI_HEADER_DIGEST_NONE);
+				} else {
+					iscsi_set_error(iscsi,
+						"Invalid URL argument for header_digest: %s", value);
+					return NULL;
+				}
+			}
+			if (!strcmp(key, "data_digest")) {
+				if (!strcmp(value, "crc32c")) {
+					iscsi_set_data_digest(
+						iscsi, ISCSI_DATA_DIGEST_CRC32C);
+				} else if (!strcmp(value, "none")) {
+					iscsi_set_data_digest(
+						iscsi, ISCSI_DATA_DIGEST_NONE);
+				} else {
+					iscsi_set_error(iscsi,
+						"Invalid URL argument for data_digest: %s", value);
+					return NULL;
+				}
+			}
 			if (!strcmp(key, "target_user")) {
 				target_user = value;
 			} else if (!strcmp(key, "target_password")) {
diff --git a/lib/libiscsi.def b/lib/libiscsi.def
index c56fe59..6b59726 100644
--- a/lib/libiscsi.def
+++ b/lib/libiscsi.def
@@ -115,6 +115,7 @@ iscsi_set_initial_r2t
 iscsi_set_log_level
 iscsi_set_log_fn
 iscsi_set_header_digest
+iscsi_set_data_digest
 iscsi_set_initiator_username_pwd
 iscsi_set_isid_en
 iscsi_set_isid_oui
diff --git a/lib/libiscsi.syms.in b/lib/libiscsi.syms.in
index 2eb50a7..daf2b0f 100644
--- a/lib/libiscsi.syms.in
+++ b/lib/libiscsi.syms.in
@@ -116,6 +116,7 @@ iscsi_set_alias
 iscsi_set_bind_interfaces
 iscsi_set_cache_allocations
 iscsi_set_header_digest
+iscsi_set_data_digest
 iscsi_set_immediate_data
 iscsi_set_initial_r2t
 iscsi_set_initiator_username_pwd
diff --git a/lib/login.c b/lib/login.c
index 8251d16..268c409 100644
--- a/lib/login.c
+++ b/lib/login.c
@@ -44,6 +44,10 @@
 #include "iscsi-private.h"
 #include "scsi-lowlevel.h"
 #include "md5.h"
+
+#ifdef HAVE_LIBGNUTLS
+#include <gnutls/crypto.h>
+#endif
 #ifdef HAVE_LIBGCRYPT
 #include <gcrypt.h>
 #endif
@@ -202,7 +206,24 @@ iscsi_login_add_datadigest(struct iscsi_context *iscsi, struct iscsi_pdu *pdu)
 		return 0;
 	}
 
-	strncpy(str,"DataDigest=None",MAX_STRING_SIZE);
+	switch (iscsi->want_data_digest) {
+	case ISCSI_DATA_DIGEST_NONE:
+		strncpy(str,"DataDigest=None",MAX_STRING_SIZE);
+		break;
+	case ISCSI_DATA_DIGEST_NONE_CRC32C:
+		strncpy(str,"DataDigest=None,CRC32C",MAX_STRING_SIZE);
+		break;
+	case ISCSI_DATA_DIGEST_CRC32C_NONE:
+		strncpy(str,"DataDigest=CRC32C,None",MAX_STRING_SIZE);
+		break;
+	case ISCSI_DATA_DIGEST_CRC32C:
+		strncpy(str,"DataDigest=CRC32C",MAX_STRING_SIZE);
+		break;
+	default:
+		iscsi_set_error(iscsi, "invalid data digest value");
+		return -1;
+	}
+
 	if (iscsi_pdu_add_data(iscsi, pdu, (unsigned char *)str, strlen(str)+1)
 	    != 0) {
 		iscsi_set_error(iscsi, "Out-of-memory: pdu add data failed.");
@@ -681,41 +702,61 @@ i2h(int i)
 	return i + '0';
 }
 
-#ifndef HAVE_LIBGCRYPT
-typedef struct MD5Context *gcry_md_hd_t;
-#define gcry_md_write MD5Update
-#define GCRY_MD_MD5 1
+#if defined HAVE_LIBGNUTLS
+#define md5_context_t gnutls_hash_hd_t
+#define md5_open(hd)  gnutls_hash_init(hd, GNUTLS_DIG_MD5)
+#define md5_write     gnutls_hash
+#define md5_read      gnutls_hash_output
 
-static void gcry_md_open(gcry_md_hd_t *hd, int algo, unsigned int flags)
+static void md5_close(md5_context_t h)
+{
+       unsigned char digest[16];
+
+       gnutls_hash_deinit(h, digest);
+}
+
+#elif defined HAVE_LIBGCRYPT
+typedef gcry_md_hd_t md5_context_t;
+#define md5_open(hd) gcry_md_open(hd, GCRY_MD_MD5, 0)
+#define md5_write gcry_md_write
+#define md5_close gcry_md_close
+
+static void md5_read(md5_context_t h, uint8_t *result)
+{
+	memcpy(result, gcry_md_read(h, 0), 16);
+}
+#else
+typedef struct MD5Context *md5_context_t;
+#define md5_write MD5Update
+
+static void md5_open(md5_context_t *hd)
 {
-	assert(algo == GCRY_MD_MD5 && flags == 0);
 	*hd = malloc(sizeof(struct MD5Context));
 	if (*hd) {
 		MD5Init(*hd);
 	}
 }
 
-static void gcry_md_putc(gcry_md_hd_t h, unsigned char c)
-{
-	MD5Update(h, &c, 1);
-}
-
-static char *gcry_md_read(gcry_md_hd_t h, int algo)
+static void md5_read(md5_context_t h, uint8_t *result)
 {
 	unsigned char digest[16];
-	assert(algo == 0 || algo == GCRY_MD_MD5);
 
 	MD5Final(digest, h);
-	return memcpy(h->buf, digest, sizeof(digest));
+	memcpy(result, digest, sizeof(digest));
 }
 
-static void gcry_md_close(gcry_md_hd_t h)
+static void md5_close(md5_context_t h)
 {
 	memset(h, 0, sizeof(*h));
 	free(h);
 }
 #endif
 
+static inline void md5_putc(md5_context_t h, unsigned char c)
+{
+	md5_write(h, &c, 1);
+}
+
 /* size of the challenge used for bidirectional chap */
 #define TARGET_CHAP_C_SIZE 32
 
@@ -726,7 +767,7 @@ iscsi_login_add_chap_response(struct iscsi_context *iscsi, struct iscsi_pdu *pdu
 	char * strp;
 	unsigned char c, cc[2];
 	unsigned char digest[CHAP_R_SIZE];
-	gcry_md_hd_t ctx;
+	md5_context_t ctx;
 	int i;
 
 	if (iscsi->current_phase != ISCSI_PDU_LOGIN_CSG_SECNEG
@@ -739,22 +780,22 @@ iscsi_login_add_chap_response(struct iscsi_context *iscsi, struct iscsi_pdu *pdu
 		return -1;
 	}
 
-	gcry_md_open(&ctx, GCRY_MD_MD5, 0);
+	md5_open(&ctx);
 	if (ctx == NULL) {
 		iscsi_set_error(iscsi, "Cannot create MD5 algorithm");
 		return -1;
 	}
-	gcry_md_putc(ctx, iscsi->chap_i);
-	gcry_md_write(ctx, (unsigned char *)iscsi->passwd, strlen(iscsi->passwd));
+	md5_putc(ctx, iscsi->chap_i);
+	md5_write(ctx, (unsigned char *)iscsi->passwd, strlen(iscsi->passwd));
 
 	strp = iscsi->chap_c;
 	while (*strp != 0) {
 		c = (h2i(strp[0]) << 4) | h2i(strp[1]);
 		strp += 2;
-		gcry_md_putc(ctx, c);
+		md5_putc(ctx, c);
 	}
-	memcpy(digest, gcry_md_read(ctx, 0), sizeof(digest));
-	gcry_md_close(ctx);
+	md5_read(ctx, digest);
+	md5_close(ctx);
 
 	strncpy(str,"CHAP_R=0x",MAX_STRING_SIZE);
 	if (iscsi_pdu_add_data(iscsi, pdu, (unsigned char *)str, strlen(str))
@@ -822,20 +863,19 @@ iscsi_login_add_chap_response(struct iscsi_context *iscsi, struct iscsi_pdu *pdu
 			return -1;
 		}
 
-		gcry_md_open(&ctx, GCRY_MD_MD5, 0);
+		md5_open(&ctx);
 		if (ctx == NULL) {
 			iscsi_set_error(iscsi, "Cannot create MD5 algorithm");
 			return -1;
 		}
-		gcry_md_putc(ctx, iscsi->target_chap_i);
-		gcry_md_write(ctx, (unsigned char *)iscsi->target_passwd,
+		md5_putc(ctx, iscsi->target_chap_i);
+		md5_write(ctx, (unsigned char *)iscsi->target_passwd,
 			      strlen(iscsi->target_passwd));
-		gcry_md_write(ctx, (unsigned char *)target_chap_c,
+		md5_write(ctx, (unsigned char *)target_chap_c,
 			      TARGET_CHAP_C_SIZE);
 
-		memcpy(iscsi->target_chap_r, gcry_md_read(ctx, 0),
-		       sizeof(iscsi->target_chap_r));
-		gcry_md_close(ctx);
+		md5_read(ctx, iscsi->target_chap_r);
+		md5_close(ctx);
 	}
 
 	return 0;
@@ -1200,6 +1240,16 @@ iscsi_process_login_reply(struct iscsi_context *iscsi, struct iscsi_pdu *pdu,
 			}
 		}
 
+		if (!strncmp(ptr, "DataDigest=", 11)) {
+			if (!strcmp(ptr + 11, "CRC32C")) {
+				iscsi->want_data_digest
+				  = ISCSI_DATA_DIGEST_CRC32C;
+			} else {
+				iscsi->want_data_digest
+				  = ISCSI_DATA_DIGEST_NONE;
+			}
+		}
+
 		if (!strncmp(ptr, "FirstBurstLength=", 17)) {
 			iscsi->first_burst_length = strtol(ptr + 17, NULL, 10);
 		}
@@ -1370,6 +1420,7 @@ iscsi_process_login_reply(struct iscsi_context *iscsi, struct iscsi_pdu *pdu,
 		iscsi->is_loggedin = 1;
 		iscsi_itt_post_increment(iscsi);
 		iscsi->header_digest  = iscsi->want_header_digest;
+		iscsi->data_digest  = iscsi->want_data_digest;
 		ISCSI_LOG(iscsi, 2, "login successful");
 		pdu->callback(iscsi, SCSI_STATUS_GOOD, NULL, pdu->private_data);
 	} else {
diff --git a/lib/pdu.c b/lib/pdu.c
index 5a97e43..be0a646 100644
--- a/lib/pdu.c
+++ b/lib/pdu.c
@@ -225,6 +225,9 @@ iscsi_allocate_pdu(struct iscsi_context *iscsi, enum iscsi_opcode opcode,
 	/* flags */
 	pdu->flags = flags;
 
+	/* DataDigest - may or may not be calculated.  Initialize anyway. */
+	crc32c_init(&pdu->calculated_data_digest);
+
 	return pdu;
 }
 
@@ -537,6 +540,25 @@ iscsi_process_pdu(struct iscsi_context *iscsi, struct iscsi_in_pdu *in)
 		}
 	}
 
+	/* verify data checksum ... */
+	if (iscsi->data_digest != ISCSI_DATA_DIGEST_NONE) {
+		int dsl = scsi_get_uint32(&in->hdr[4]) & 0x00ffffff;
+		/* ... but only if some data is present. */
+		if (dsl) {
+			uint32_t crc_rcvd = 0;
+			uint32_t crc = crc32c_chain_done(in->calculated_data_digest);
+
+			crc_rcvd |= in->data_digest_buf[0];
+			crc_rcvd |= in->data_digest_buf[1] << 8;
+			crc_rcvd |= in->data_digest_buf[2] << 16;
+			crc_rcvd |= in->data_digest_buf[3] << 24;
+			if (crc != crc_rcvd) {
+				iscsi_set_error(iscsi, "data checksum verification failed: calculated 0x%" PRIx32 " received 0x%" PRIx32, crc, crc_rcvd);
+				return -1;
+			}
+		}
+	}
+
 	if (ahslen != 0) {
 		iscsi_set_error(iscsi, "cant handle expanded headers yet");
 		return -1;
@@ -947,3 +969,36 @@ iscsi_cancel_pdus(struct iscsi_context *iscsi)
 		iscsi->drv->free_pdu(iscsi, pdu);
 	}
 }
+
+void
+iscsi_cancel_lun_pdus(struct iscsi_context *iscsi, uint32_t lun)
+{
+	struct iscsi_pdu *pdu;
+	struct iscsi_pdu *next_pdu;
+	uint32_t cmdsn_gap = 0;
+	struct scsi_task * task = NULL;
+
+	for (pdu = iscsi->outqueue; pdu; pdu = next_pdu) {
+		next_pdu = pdu->next;
+		task = iscsi_scsi_get_task_from_pdu(pdu);
+
+		if (cmdsn_gap > 0) {
+			iscsi_pdu_set_cmdsn(pdu, pdu->cmdsn - cmdsn_gap);
+		}
+		if (task == NULL || task->lun != lun) {
+			continue;
+		}
+		if (!(pdu->outdata.data[0] & ISCSI_PDU_IMMEDIATE) &&
+		    (pdu->outdata.data[0] & 0x3f) != ISCSI_PDU_DATA_OUT) {
+			iscsi->cmdsn--;
+			cmdsn_gap++;
+		}
+		ISCSI_LIST_REMOVE(&iscsi->outqueue, pdu);
+		iscsi_set_error(iscsi, "command cancelled");
+		if (pdu->callback) {
+			pdu->callback(iscsi, SCSI_STATUS_CANCELLED,
+				NULL, pdu->private_data);
+		}
+		iscsi->drv->free_pdu(iscsi, pdu);
+	}
+}
diff --git a/lib/scsi-lowlevel.c b/lib/scsi-lowlevel.c
index 1b49853..e23ec0d 100644
--- a/lib/scsi-lowlevel.c
+++ b/lib/scsi-lowlevel.c
@@ -79,7 +79,9 @@ scsi_free_scsi_task(struct scsi_task *task)
 	}
 
 	free(task->datain.data);
+	task->datain.data = NULL;
 	free(task);
+	task = NULL;
 }
 
 struct scsi_task *
diff --git a/lib/socket.c b/lib/socket.c
index db7f667..d8fbfc9 100644
--- a/lib/socket.c
+++ b/lib/socket.c
@@ -62,6 +62,7 @@
 #include <sys/uio.h>
 #endif
 
+#include <stdbool.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -514,7 +515,7 @@ iscsi_out_queue_length(struct iscsi_context *iscsi)
 }
 
 ssize_t
-iscsi_iovector_readv_writev(struct iscsi_context *iscsi, struct scsi_iovector *iovector, uint32_t pos, ssize_t count, int do_write)
+iscsi_iovector_readv_writev(struct iscsi_context *iscsi, struct scsi_iovector *iovector, uint32_t pos, ssize_t count, uint32_t *data_digest_ptr, int do_write)
 {
 	struct scsi_iovec *iov, *iov2;
 	int niov;
@@ -598,6 +599,19 @@ iscsi_iovector_readv_writev(struct iscsi_context *iscsi, struct scsi_iovector *i
 		n = readv(iscsi->fd, (struct iovec*) iov, niov);
 	}
 
+	/* Update the data digest */
+	if (data_digest_ptr && n > 0) {
+		int i;
+		size_t bytes_to_crc = n;
+		struct iovec *iov_ptr = (struct iovec*)iov;
+
+		for ( i=0; iov_ptr && i<niov && bytes_to_crc; iov_ptr++, i++) {
+			size_t chunk = MIN(bytes_to_crc, iov_ptr->iov_len);
+			*data_digest_ptr = crc32c_chain(*data_digest_ptr, iov_ptr->iov_base, chunk);
+			bytes_to_crc -= chunk;
+		}
+	}
+
 	/* restore original values */
 	iov->iov_base = (void*) ((uintptr_t)iov->iov_base - pos);
 	iov->iov_len += pos;
@@ -619,6 +633,7 @@ iscsi_read_from_socket(struct iscsi_context *iscsi)
 {
 	struct iscsi_in_pdu *in;
 	ssize_t hdr_size, data_size, count, padding_size;
+	bool do_data_digest = (iscsi->data_digest != ISCSI_DATA_DIGEST_NONE);
 
 	do {
 		hdr_size = ISCSI_HEADER_SIZE(iscsi->header_digest);
@@ -628,6 +643,7 @@ iscsi_read_from_socket(struct iscsi_context *iscsi)
 				iscsi_set_error(iscsi, "Out-of-memory: failed to malloc iscsi_in_pdu");
 				return -1;
 			}
+			crc32c_init(&(iscsi->incoming->calculated_data_digest));
 			iscsi->incoming->hdr = iscsi_smalloc(iscsi, hdr_size);
 			if (iscsi->incoming->hdr == NULL) {
 				iscsi_set_error(iscsi, "Out-of-memory");
@@ -682,7 +698,7 @@ iscsi_read_from_socket(struct iscsi_context *iscsi)
 			iovector_in = iscsi_get_scsi_task_iovector_in(iscsi, in);
 			if (iovector_in != NULL && count > padding_size) {
 				uint32_t offset = scsi_get_uint32(&in->hdr[40]);
-				count = iscsi_iovector_readv_writev(iscsi, iovector_in, in->data_pos + offset, count - padding_size, 0);
+				count = iscsi_iovector_readv_writev(iscsi, iovector_in, in->data_pos + offset, count - padding_size, do_data_digest ? &(in->calculated_data_digest) : NULL, 0);
 			} else {
 				if (iovector_in == NULL) {
 					if (in->data == NULL) {
@@ -695,6 +711,8 @@ iscsi_read_from_socket(struct iscsi_context *iscsi)
 					buf = &in->data[in->data_pos];
 				}
 				count = recv(iscsi->fd, (void *)buf, count, 0);
+				if (do_data_digest && count > 0)
+					in->calculated_data_digest = crc32c_chain(in->calculated_data_digest, buf, count);
 			}
 			if (count == 0) {
 				/* remote side has closed the socket. */
@@ -713,6 +731,28 @@ iscsi_read_from_socket(struct iscsi_context *iscsi)
 			break;
 		}
 
+		/* Handle Data Digest receive */
+		if (data_size != 0 && do_data_digest &&
+			in->received_data_digest_bytes < ISCSI_DIGEST_SIZE) {
+
+			count = recv(iscsi->fd, (void *)(in->data_digest_buf + in->received_data_digest_bytes), ISCSI_DIGEST_SIZE - in->received_data_digest_bytes, 0);
+			if (count == 0) {
+				/* remote side has closed the socket. */
+				return -1;
+			}
+			if (count < 0) {
+				if (errno == EINTR || errno == EAGAIN) {
+					break;
+				}
+				return -1;
+			}
+			in->received_data_digest_bytes += count;
+
+			if (in->received_data_digest_bytes < ISCSI_DIGEST_SIZE) {
+				break;
+			}
+		}
+
 		iscsi->incoming = NULL;
 		if (iscsi_process_pdu(iscsi, in) != 0) {
 			iscsi_free_iscsi_in_pdu(iscsi, in);
@@ -751,6 +791,7 @@ iscsi_write_to_socket(struct iscsi_context *iscsi)
 	struct iscsi_pdu *pdu;
 	static char padding_buf[3];
 	int socket_flags = 0;
+	bool do_data_digest = (iscsi->data_digest != ISCSI_DATA_DIGEST_NONE);
 
 #ifdef MSG_NOSIGNAL
 	socket_flags |= MSG_NOSIGNAL;
@@ -848,7 +889,7 @@ iscsi_write_to_socket(struct iscsi_context *iscsi)
 			count = iscsi_iovector_readv_writev(iscsi,
 				iovector_out,
 				pdu->payload_offset + pdu->payload_written,
-				pdu->payload_len - pdu->payload_written, 1);
+				pdu->payload_len - pdu->payload_written, do_data_digest ? &(pdu->calculated_data_digest) : NULL, 1);
 			if (count == -1) {
 				if (errno == EAGAIN || errno == EWOULDBLOCK) {
 					return 0;
@@ -873,12 +914,56 @@ iscsi_write_to_socket(struct iscsi_context *iscsi)
 						"socket :%d", errno);
 				return -1;
 			}
+
+			if (do_data_digest)
+				pdu->calculated_data_digest = crc32c_chain(pdu->calculated_data_digest, (uint8_t *)padding_buf, count);
+
 			pdu->payload_written += count;
 		}
+
 		/* if we havent written the full padding yet. */
+		if (pdu->payload_written < total) {
+			return 0;
+		}
+
+		/*
+		 * Maybe update the total again, and write the digest, but only if
+		 * 1. DataDigest has been negociated, and
+		 * 2. We have actually written some data
+		 */
+		if (do_data_digest && pdu->payload_written) {
+			uint32_t data_digest = crc32c_chain_done(pdu->calculated_data_digest);
+			char data_digest_buf[ISCSI_DIGEST_SIZE];
+
+			total += ISCSI_DIGEST_SIZE;
+
+			data_digest_buf[3] = (data_digest >> 24);
+			data_digest_buf[2] = (data_digest >> 16);
+			data_digest_buf[1] = (data_digest >>  8);
+			data_digest_buf[0] = (data_digest);
+
+			/* Write data digest */
+			if (pdu->payload_written < total) {
+				int todo = total - pdu->payload_written;
+				count = send(iscsi->fd, data_digest_buf + (ISCSI_DIGEST_SIZE - todo), todo, socket_flags);
+				if (count == -1) {
+					if (errno == EAGAIN || errno == EWOULDBLOCK) {
+						return 0;
+					}
+					iscsi_set_error(iscsi, "Error when writing to "
+							"socket :%d", errno);
+					return -1;
+				}
+
+				pdu->payload_written += count;
+			}
+		}
+
+		/* if we havent written everything yet. */
 		if (pdu->payload_written != total) {
 			return 0;
 		}
+
 		if (pdu->flags & ISCSI_PDU_CORK_WHEN_SENT) {
 			iscsi->is_corked = 1;
 		}
diff --git a/lib/task_mgmt.c b/lib/task_mgmt.c
index b0ad251..f3e6824 100644
--- a/lib/task_mgmt.c
+++ b/lib/task_mgmt.c
@@ -130,7 +130,7 @@ iscsi_task_mgmt_lun_reset_async(struct iscsi_context *iscsi,
 		      uint32_t lun,
 		      iscsi_command_cb cb, void *private_data)
 {
-	iscsi_scsi_cancel_all_tasks(iscsi);
+	iscsi_cancel_lun_pdus(iscsi, lun);
 
 	return iscsi_task_mgmt_async(iscsi,
 		      lun, ISCSI_TM_LUN_RESET,
diff --git a/packaging/RPM/libiscsi.spec.in b/packaging/RPM/libiscsi.spec.in
index 4afa9d3..19602b0 100644
--- a/packaging/RPM/libiscsi.spec.in
+++ b/packaging/RPM/libiscsi.spec.in
@@ -1,6 +1,6 @@
 Name: libiscsi
 Summary: iSCSI client library
-Version: 1.19.0
+Version: 1.20.0
 Release: 1GITHASH%{?dist}
 License: LGPLv2+
 Group: System Environment/Libraries
@@ -75,9 +75,13 @@ to iSCSI servers without having to set up the Linux iSCSI initiator.
 %{_bindir}/iscsi-perf
 %{_bindir}/iscsi-readcapacity16
 %{_bindir}/iscsi-swp
+%{_bindir}/iscsi-discard
+%{_bindir}/iscsi-md5sum
+%{_bindir}/iscsi-pr
 %{_mandir}/man1/iscsi-inq.1.gz
 %{_mandir}/man1/iscsi-ls.1.gz
 %{_mandir}/man1/iscsi-swp.1.gz
+%{_mandir}/man1/iscsi-md5sum.1.gz
 
 %package devel
 Summary: iSCSI client development libraries
@@ -109,6 +113,8 @@ Test tool for iSCSI/SCSI targets
 
 
 %changelog
+* Mon Feb 5 2024 : 1.20.0
+ - Various updates to the test tool
 * Sun Jul 14 2019 : 1.19.0
  - iSER improvements
  - Add support to senable/disable digests via URL arguments
@@ -229,7 +235,7 @@ Test tool for iSCSI/SCSI targets
  - Change all default iqn names so they are valid iqn names.
 * Mon Jul 9 2012 : 1.5.0
  - Make sure we can handle racy eventsystems which might call us for 
-   POLLIN eventhough there is no longer any data to read from the socket.
+   POLLIN even though there is no longer any data to read from the socket.
  - Only set up tcp keepalives on systems that support them.
  - Only export symbols we really want to make public
  - FreeBSD and Illumos does not define SOL_TCP
diff --git a/test-tool/iscsi-support.c b/test-tool/iscsi-support.c
index 9363140..9375952 100644
--- a/test-tool/iscsi-support.c
+++ b/test-tool/iscsi-support.c
@@ -202,7 +202,7 @@ static int check_result(const char *opcode, struct scsi_device *sdev,
         }
         if (status == SCSI_STATUS_GOOD && task->status != SCSI_STATUS_GOOD) {
                 logging(LOG_NORMAL,
-                        "[FAILED] %s command failed with status %d / sense key %s(0x%02x) / ASCQ %s(0x%04x)",
+                        "[FAILED] %s command failed with status 0x%x / sense key %s(0x%02x) / ASCQ %s(0x%04x)",
                         opcode, task->status,
                         scsi_sense_key_str(task->sense.key), task->sense.key,
                         scsi_sense_ascq_str(task->sense.ascq), task->sense.ascq);
@@ -457,6 +457,8 @@ void logging(int level, const char *format, ...)
         va_list ap;
         static char message[1024];
         int ret;
+        struct timespec ts;
+        struct tm tm;
 
         if (loglevel < level) {
                 return;
@@ -467,6 +469,17 @@ void logging(int level, const char *format, ...)
                 return;
         }
 
+        if (clock_gettime(CLOCK_REALTIME, &ts) == -1) {
+                return;
+	}
+
+        if (!localtime_r(&ts.tv_sec, &tm)) {
+                return;
+        }
+
+        printf("    %04d-%02d-%02d %02d:%02d:%02d.%06d ",
+                tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday, tm.tm_hour, tm.tm_min, tm.tm_sec, (int)ts.tv_nsec / 1000);
+
         va_start(ap, format);
         ret = vsnprintf(message, 1024, format, ap);
         va_end(ap);
@@ -2735,7 +2748,7 @@ int set_swp(struct scsi_device *sdev)
         logging(LOG_VERBOSE, "[SUCCESS] CONTROL page fetched.");
 
         ms = scsi_datain_unmarshall(sense_task);
-        if (ms == NULL) {
+        if (ms == NULL || ms->pages == NULL) {
                 logging(LOG_NORMAL, "failed to unmarshall mode sense datain "
                         "blob");
                 ret = -1;
diff --git a/test-tool/test_compareandwrite_miscompare.c b/test-tool/test_compareandwrite_miscompare.c
index 04a9fb5..a8bdef3 100644
--- a/test-tool/test_compareandwrite_miscompare.c
+++ b/test-tool/test_compareandwrite_miscompare.c
@@ -95,7 +95,7 @@ test_compareandwrite_miscompare(void)
                 for (j = 0; j < i * block_size; j++) {
                         if (scratch[j] != 'A') {
                                 logging(LOG_VERBOSE, "[FAILED] Data changed "
-                                        "eventhough there was a miscompare");
+                                        "even though there was a miscompare");
                                 CU_FAIL("Block was written to");
                                 return;
                         }
@@ -151,7 +151,7 @@ test_compareandwrite_miscompare(void)
                 for (j = 0; j < i * block_size; j++) {
                         if (scratch[j] != 'A') {
                                 logging(LOG_VERBOSE, "[FAILED] Data changed "
-                                        "eventhough there was a miscompare");
+                                        "even though there was a miscompare");
                                 CU_FAIL("Block was written to");
                                 return;
                         }
diff --git a/test-tool/test_sanitize_block_erase.c b/test-tool/test_sanitize_block_erase.c
index 15940be..cea72b9 100644
--- a/test-tool/test_sanitize_block_erase.c
+++ b/test-tool/test_sanitize_block_erase.c
@@ -161,7 +161,7 @@ check_unmap(void)
                         lbas->descriptors[i].lba + lbas->descriptors[i].num_blocks);
                 if (lbas->descriptors[i].provisioning == SCSI_PROVISIONING_TYPE_MAPPED) {
                           logging(LOG_VERBOSE, "[FAILED] Descriptor %d is MAPPED."
-                                "All descriptors shoudl be either DEALLOCATED "
+                                "All descriptors should be either DEALLOCATED "
                                 "or ANCHORED after SANITIZE", i);
                           CU_FAIL("[FAILED] LBA status descriptor is MAPPED.");
                 }
diff --git a/test-tool/test_sanitize_reset.c b/test-tool/test_sanitize_reset.c
index fffc55a..eed451f 100644
--- a/test-tool/test_sanitize_reset.c
+++ b/test-tool/test_sanitize_reset.c
@@ -58,7 +58,7 @@ test_sanitize_reset(void)
                 return;
         }
 
-        logging(LOG_VERBOSE, "Send an asyncronous SANITIZE to the target.");
+        logging(LOG_VERBOSE, "Send an asynchronous SANITIZE to the target.");
         data.size = block_size + 4;
         data.data = alloca(data.size);
         memset(&data.data[4], 0, block_size);
diff --git a/utils/iscsi-perf.c b/utils/iscsi-perf.c
index b43d949..f2f6aee 100644
--- a/utils/iscsi-perf.c
+++ b/utils/iscsi-perf.c
@@ -151,7 +151,7 @@ void cb(struct iscsi_context *iscsi, int status, void *command_data, void *priva
 	if (status == SCSI_STATUS_BUSY ||
 		(status == SCSI_STATUS_CHECK_CONDITION && task->sense.key == SCSI_SENSE_UNIT_ATTENTION)) {
 		if (client->retry_cnt++ > 4 * max_in_flight) {
-			fprintf(stderr, "maxium number of command retries reached...\n");
+			fprintf(stderr, "maximum number of command retries reached...\n");
 			client->err_cnt++;
 			goto out;
 		}
diff --git a/utils/iscsi-pr.c b/utils/iscsi-pr.c
index 309e6ca..71ae48c 100644
--- a/utils/iscsi-pr.c
+++ b/utils/iscsi-pr.c
@@ -236,7 +236,7 @@ static void print_help(const char *bin)
         fprintf(stderr, "  -S, --param-sark=SARK          PR Out: parameter service action reservation key (SARK is in hex)\n");
         fprintf(stderr, "  -T, --prout-type=TYPE          PR Out: type field\n");
         fprintf(stderr, "  -G, --register                 PR Out: Register\n");
-        fprintf(stderr, "  -R, --reserve                  PR Out: Reserve, SARK only(register sark implicity)\n");
+        fprintf(stderr, "  -R, --reserve                  PR Out: Reserve, SARK only(register sark implicitly)\n");
         fprintf(stderr, "  -L, --release                  PR Out: Release, SARK only. This program releases TYPE 7 and TYPE 8 only\n");
         fprintf(stderr, "  -C, --clear                    PR Out: Clear, SARK only\n");
         fprintf(stderr, "  -P, --preempt                  PR Out: Preempt, use SARK to preempt reservation from RK\n");