/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2012 The FreeBSD Foundation
 *
 * This software was developed by Edward Tomasz Napierala under sponsorship
 * from the FreeBSD Foundation.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 */

#include <sys/types.h>
#include <sys/ioctl.h>
#include <assert.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <netinet/in.h>

#include "iscsid.h"
#include "iscsi_proto.h"

static int
login_nsg(const struct pdu *response)
{
        struct iscsi_bhs_login_response *bhslr;

        bhslr = (struct iscsi_bhs_login_response *)response->pdu_bhs;

        return (bhslr->bhslr_flags & 0x03);
}

static void
login_set_nsg(struct pdu *request, int nsg)
{
        struct iscsi_bhs_login_request *bhslr;

        assert(nsg == BHSLR_STAGE_SECURITY_NEGOTIATION ||
            nsg == BHSLR_STAGE_OPERATIONAL_NEGOTIATION ||
            nsg == BHSLR_STAGE_FULL_FEATURE_PHASE);

        bhslr = (struct iscsi_bhs_login_request *)request->pdu_bhs;

        bhslr->bhslr_flags &= 0xFC;
        bhslr->bhslr_flags |= nsg;
}

static void
login_set_csg(struct pdu *request, int csg)
{
        struct iscsi_bhs_login_request *bhslr;

        assert(csg == BHSLR_STAGE_SECURITY_NEGOTIATION ||
            csg == BHSLR_STAGE_OPERATIONAL_NEGOTIATION ||
            csg == BHSLR_STAGE_FULL_FEATURE_PHASE);

        bhslr = (struct iscsi_bhs_login_request *)request->pdu_bhs;

        bhslr->bhslr_flags &= 0xF3;
        bhslr->bhslr_flags |= csg << 2;
}

static const char *
login_target_error_str(int class, int detail)
{
        static char msg[128];

        /*
         * RFC 3270, 10.13.5.  Status-Class and Status-Detail
         */
        switch (class) {
        case 0x01:
                switch (detail) {
                case 0x01:
                        return ("Target moved temporarily");
                case 0x02:
                        return ("Target moved permanently");
                default:
                        snprintf(msg, sizeof(msg), "unknown redirection; "
                            "Status-Class 0x%x, Status-Detail 0x%x",
                            class, detail);
                        return (msg);
                }
        case 0x02:
                switch (detail) {
                case 0x00:
                        return ("Initiator error");
                case 0x01:
                        return ("Authentication failure");
                case 0x02:
                        return ("Authorization failure");
                case 0x03:
                        return ("Not found");
                case 0x04:
                        return ("Target removed");
                case 0x05:
                        return ("Unsupported version");
                case 0x06:
                        return ("Too many connections");
                case 0x07:
                        return ("Missing parameter");
                case 0x08:
                        return ("Can't include in session");
                case 0x09:
                        return ("Session type not supported");
                case 0x0a:
                        return ("Session does not exist");
                case 0x0b:
                        return ("Invalid during login");
                default:
                        snprintf(msg, sizeof(msg), "unknown initiator error; "
                            "Status-Class 0x%x, Status-Detail 0x%x",
                            class, detail);
                        return (msg);
                }
        case 0x03:
                switch (detail) {
                case 0x00:
                        return ("Target error");
                case 0x01:
                        return ("Service unavailable");
                case 0x02:
                        return ("Out of resources");
                default:
                        snprintf(msg, sizeof(msg), "unknown target error; "
                            "Status-Class 0x%x, Status-Detail 0x%x",
                            class, detail);
                        return (msg);
                }
        default:
                snprintf(msg, sizeof(msg), "unknown error; "
                    "Status-Class 0x%x, Status-Detail 0x%x",
                    class, detail);
                return (msg);
        }
}

static void
kernel_modify(const struct iscsid_connection *conn, const char *target_address)
{
        struct iscsi_session_modify ism;
        int error;

        memset(&ism, 0, sizeof(ism));
        ism.ism_session_id = conn->conn_session_id;
        memcpy(&ism.ism_conf, &conn->conn_conf, sizeof(ism.ism_conf));
        strlcpy(ism.ism_conf.isc_target_addr, target_address,
            sizeof(ism.ism_conf.isc_target_addr));
        error = ioctl(conn->conn_iscsi_fd, ISCSISMODIFY, &ism);
        if (error != 0) {
                log_err(1, "failed to redirect to %s: ISCSISMODIFY",
                    target_address);
        }
}

/*
 * XXX: The way it works is suboptimal; what should happen is described
 *      in draft-gilligan-iscsi-fault-tolerance-00.  That, however, would
 *      be much more complicated: we would need to keep "dependencies"
 *      for sessions, so that, in case described in draft and using draft
 *      terminology, we would have three sessions: one for discovery,
 *      one for initial target portal, and one for redirect portal.
 *      This would allow us to "backtrack" on connection failure,
 *      as described in draft.
 */
static void
login_handle_redirection(struct iscsid_connection *conn, struct pdu *response)
{
        struct iscsi_bhs_login_response *bhslr;
        struct keys *response_keys;
        const char *target_address;

        bhslr = (struct iscsi_bhs_login_response *)response->pdu_bhs;
        assert (bhslr->bhslr_status_class == 1);

        response_keys = keys_new();
        keys_load_pdu(response_keys, response);

        target_address = keys_find(response_keys, "TargetAddress");
        if (target_address == NULL)
                log_errx(1, "received redirection without TargetAddress");
        if (target_address[0] == '\0')
                log_errx(1, "received redirection with empty TargetAddress");
        if (strlen(target_address) >=
            sizeof(conn->conn_conf.isc_target_addr) - 1)
                log_errx(1, "received TargetAddress is too long");

        log_debugx("received redirection to \"%s\"", target_address);
        kernel_modify(conn, target_address);
        keys_delete(response_keys);
}

static struct pdu *
login_receive(struct connection *conn)
{
        struct pdu *response;
        struct iscsi_bhs_login_response *bhslr;
        const char *errorstr;
        static bool initial = true;

        response = pdu_new(conn);
        pdu_receive(response);
        if (response->pdu_bhs->bhs_opcode != ISCSI_BHS_OPCODE_LOGIN_RESPONSE) {
                log_errx(1, "protocol error: received invalid opcode 0x%x",
                    response->pdu_bhs->bhs_opcode);
        }
        bhslr = (struct iscsi_bhs_login_response *)response->pdu_bhs;
        /*
         * XXX: Implement the C flag some day.
         */
        if ((bhslr->bhslr_flags & BHSLR_FLAGS_CONTINUE) != 0)
                log_errx(1, "received Login PDU with unsupported \"C\" flag");
        if (bhslr->bhslr_version_max != 0x00)
                log_errx(1, "received Login PDU with unsupported "
                    "Version-max 0x%x", bhslr->bhslr_version_max);
        if (bhslr->bhslr_version_active != 0x00)
                log_errx(1, "received Login PDU with unsupported "
                    "Version-active 0x%x", bhslr->bhslr_version_active);
        if (bhslr->bhslr_status_class == 1) {
                login_handle_redirection((struct iscsid_connection *)conn,
                    response);
                log_debugx("redirection handled; exiting");
                exit(0);
        }
        if (bhslr->bhslr_status_class != 0) {
                errorstr = login_target_error_str(bhslr->bhslr_status_class,
                    bhslr->bhslr_status_detail);
                fail(conn, errorstr);
                log_errx(1, "target returned error: %s", errorstr);
        }
        if (initial == false &&
            ntohl(bhslr->bhslr_statsn) != conn->conn_statsn + 1) {
                /*
                 * It's a warning, not an error, to work around what seems
                 * to be bug in NetBSD iSCSI target.
                 */
                log_warnx("received Login PDU with wrong StatSN: "
                    "is %u, should be %u", ntohl(bhslr->bhslr_statsn),
                    conn->conn_statsn + 1);
        }
        conn->conn_tsih = ntohs(bhslr->bhslr_tsih);
        conn->conn_statsn = ntohl(bhslr->bhslr_statsn);

        initial = false;

        return (response);
}

static struct pdu *
login_new_request(struct connection *conn, int csg)
{
        struct pdu *request;
        struct iscsi_bhs_login_request *bhslr;
        int nsg;

        request = pdu_new(conn);
        bhslr = (struct iscsi_bhs_login_request *)request->pdu_bhs;
        bhslr->bhslr_opcode = ISCSI_BHS_OPCODE_LOGIN_REQUEST |
            ISCSI_BHS_OPCODE_IMMEDIATE;

        bhslr->bhslr_flags = BHSLR_FLAGS_TRANSIT;
        switch (csg) {
        case BHSLR_STAGE_SECURITY_NEGOTIATION:
                nsg = BHSLR_STAGE_OPERATIONAL_NEGOTIATION;
                break;
        case BHSLR_STAGE_OPERATIONAL_NEGOTIATION:
                nsg = BHSLR_STAGE_FULL_FEATURE_PHASE;
                break;
        default:
                assert(!"invalid csg");
                log_errx(1, "invalid csg %d", csg);
        }
        login_set_csg(request, csg);
        login_set_nsg(request, nsg);

        memcpy(bhslr->bhslr_isid, &conn->conn_isid, sizeof(bhslr->bhslr_isid));
        bhslr->bhslr_tsih = htons(conn->conn_tsih);
        bhslr->bhslr_initiator_task_tag = 0;
        bhslr->bhslr_cmdsn = 0;
        bhslr->bhslr_expstatsn = htonl(conn->conn_statsn + 1);

        return (request);
}

static int
login_list_prefers(const char *list,
    const char *choice1, const char *choice2)
{
        char *tofree, *str, *token;

        tofree = str = checked_strdup(list);

        while ((token = strsep(&str, ",")) != NULL) {
                if (strcmp(token, choice1) == 0) {
                        free(tofree);
                        return (1);
                }
                if (strcmp(token, choice2) == 0) {
                        free(tofree);
                        return (2);
                }
        }
        free(tofree);
        return (-1);
}

static void
login_negotiate_key(struct iscsid_connection *conn, const char *name,
    const char *value)
{
        struct iscsi_session_limits *isl;
        int which, tmp;

        isl = &conn->conn_limits;
        if (strcmp(name, "TargetAlias") == 0) {
                strlcpy(conn->conn_target_alias, value,
                    sizeof(conn->conn_target_alias));
        } else if (strcmp(value, "Irrelevant") == 0) {
                /* Ignore. */
        } else if (strcmp(name, "iSCSIProtocolLevel") == 0) {
                tmp = strtoul(value, NULL, 10);
                if (tmp < 0 || tmp > 31)
                        log_errx(1, "received invalid iSCSIProtocolLevel");
                conn->conn_protocol_level = tmp;
        } else if (strcmp(name, "HeaderDigest") == 0) {
                which = login_list_prefers(value, "CRC32C", "None");
                switch (which) {
                case 1:
                        log_debugx("target prefers CRC32C "
                            "for header digest; we'll use it");
                        conn->conn.conn_header_digest = CONN_DIGEST_CRC32C;
                        break;
                case 2:
                        log_debugx("target prefers not to do "
                            "header digest; we'll comply");
                        break;
                default:
                        log_warnx("target sent unrecognized "
                            "HeaderDigest value \"%s\"; will use None", value);
                        break;
                }
        } else if (strcmp(name, "DataDigest") == 0) {
                which = login_list_prefers(value, "CRC32C", "None");
                switch (which) {
                case 1:
                        log_debugx("target prefers CRC32C "
                            "for data digest; we'll use it");
                        conn->conn.conn_data_digest = CONN_DIGEST_CRC32C;
                        break;
                case 2:
                        log_debugx("target prefers not to do "
                            "data digest; we'll comply");
                        break;
                default:
                        log_warnx("target sent unrecognized "
                            "DataDigest value \"%s\"; will use None", value);
                        break;
                }
        } else if (strcmp(name, "MaxConnections") == 0) {
                /* Ignore. */
        } else if (strcmp(name, "InitialR2T") == 0) {
                if (strcmp(value, "Yes") == 0)
                        conn->conn_initial_r2t = true;
                else
                        conn->conn_initial_r2t = false;
        } else if (strcmp(name, "ImmediateData") == 0) {
                if (strcmp(value, "Yes") == 0)
                        conn->conn.conn_immediate_data = true;
                else
                        conn->conn.conn_immediate_data = false;
        } else if (strcmp(name, "MaxRecvDataSegmentLength") == 0) {
                tmp = strtoul(value, NULL, 10);
                if (tmp <= 0)
                        log_errx(1, "received invalid "
                            "MaxRecvDataSegmentLength");
                if (tmp > isl->isl_max_send_data_segment_length) {
                        log_debugx("capping max_send_data_segment_length "
                            "from %d to %d", tmp,
                            isl->isl_max_send_data_segment_length);
                        tmp = isl->isl_max_send_data_segment_length;
                }
                conn->conn.conn_max_send_data_segment_length = tmp;
        } else if (strcmp(name, "MaxBurstLength") == 0) {
                tmp = strtoul(value, NULL, 10);
                if (tmp <= 0)
                        log_errx(1, "received invalid MaxBurstLength");
                if (tmp > isl->isl_max_burst_length) {
                        log_debugx("capping MaxBurstLength "
                            "from %d to %d", tmp, isl->isl_max_burst_length);
                        tmp = isl->isl_max_burst_length;
                }
                conn->conn.conn_max_burst_length = tmp;
        } else if (strcmp(name, "FirstBurstLength") == 0) {
                tmp = strtoul(value, NULL, 10);
                if (tmp <= 0)
                        log_errx(1, "received invalid FirstBurstLength");
                if (tmp > isl->isl_first_burst_length) {
                        log_debugx("capping FirstBurstLength "
                            "from %d to %d", tmp, isl->isl_first_burst_length);
                        tmp = isl->isl_first_burst_length;
                }
                conn->conn.conn_first_burst_length = tmp;
        } else if (strcmp(name, "DefaultTime2Wait") == 0) {
                /* Ignore */
        } else if (strcmp(name, "DefaultTime2Retain") == 0) {
                /* Ignore */
        } else if (strcmp(name, "MaxOutstandingR2T") == 0) {
                /* Ignore */
        } else if (strcmp(name, "DataPDUInOrder") == 0) {
                /* Ignore */
        } else if (strcmp(name, "DataSequenceInOrder") == 0) {
                /* Ignore */
        } else if (strcmp(name, "ErrorRecoveryLevel") == 0) {
                /* Ignore */
        } else if (strcmp(name, "OFMarker") == 0) {
                /* Ignore */
        } else if (strcmp(name, "IFMarker") == 0) {
                /* Ignore */
        } else if (strcmp(name, "RDMAExtensions") == 0) {
                if (conn->conn_conf.isc_iser == 1 &&
                    strcmp(value, "Yes") != 0) {
                        log_errx(1, "received unsupported RDMAExtensions");
                }
        } else if (strcmp(name, "InitiatorRecvDataSegmentLength") == 0) {
                tmp = strtoul(value, NULL, 10);
                if (tmp <= 0)
                        log_errx(1, "received invalid "
                            "InitiatorRecvDataSegmentLength");
                if ((int)tmp > isl->isl_max_recv_data_segment_length) {
                        log_debugx("capping InitiatorRecvDataSegmentLength "
                            "from %d to %d", tmp,
                            isl->isl_max_recv_data_segment_length);
                        tmp = isl->isl_max_recv_data_segment_length;
                }
                conn->conn.conn_max_recv_data_segment_length = tmp;
        } else if (strcmp(name, "TargetPortalGroupTag") == 0) {
                /* Ignore */
        } else if (strcmp(name, "TargetRecvDataSegmentLength") == 0) {
                tmp = strtoul(value, NULL, 10);
                if (tmp <= 0) {
                        log_errx(1,
                            "received invalid TargetRecvDataSegmentLength");
                }
                if (tmp > isl->isl_max_send_data_segment_length) {
                        log_debugx("capping TargetRecvDataSegmentLength "
                            "from %d to %d", tmp,
                            isl->isl_max_send_data_segment_length);
                        tmp = isl->isl_max_send_data_segment_length;
                }
                conn->conn.conn_max_send_data_segment_length = tmp;
        } else {
                log_debugx("unknown key \"%s\"; ignoring",  name);
        }
}

static void
login_negotiate(struct iscsid_connection *conn)
{
        struct pdu *request, *response;
        struct keys *request_keys, *response_keys;
        struct iscsi_bhs_login_response *bhslr;
        int i, nrequests = 0;
        struct iscsi_session_limits *isl;

        log_debugx("beginning operational parameter negotiation");
        request = login_new_request(&conn->conn,
            BHSLR_STAGE_OPERATIONAL_NEGOTIATION);
        request_keys = keys_new();

        isl = &conn->conn_limits;
        log_debugx("Limits for offload \"%s\" are "
            "MaxRecvDataSegment=%d, max_send_dsl=%d, "
            "MaxBurstLength=%d, FirstBurstLength=%d",
            conn->conn_conf.isc_offload, isl->isl_max_recv_data_segment_length,
            isl->isl_max_send_data_segment_length, isl->isl_max_burst_length,
            isl->isl_first_burst_length);

        /*
         * The following keys are irrelevant for discovery sessions.
         */
        if (conn->conn_conf.isc_discovery == 0) {
                keys_add(request_keys, "iSCSIProtocolLevel", "2");
                if (conn->conn_conf.isc_header_digest != 0)
                        keys_add(request_keys, "HeaderDigest", "CRC32C");
                else
                        keys_add(request_keys, "HeaderDigest", "None");
                if (conn->conn_conf.isc_data_digest != 0)
                        keys_add(request_keys, "DataDigest", "CRC32C");
                else
                        keys_add(request_keys, "DataDigest", "None");

                keys_add(request_keys, "ImmediateData", "Yes");
                keys_add_int(request_keys, "MaxBurstLength",
                    isl->isl_max_burst_length);
                keys_add_int(request_keys, "FirstBurstLength",
                    isl->isl_first_burst_length);
                keys_add(request_keys, "InitialR2T", "Yes");
                keys_add(request_keys, "MaxOutstandingR2T", "1");
                if (conn->conn_conf.isc_iser == 1) {
                        keys_add_int(request_keys, "InitiatorRecvDataSegmentLength",
                            isl->isl_max_recv_data_segment_length);
                        keys_add_int(request_keys, "TargetRecvDataSegmentLength",
                            isl->isl_max_send_data_segment_length);
                        keys_add(request_keys, "RDMAExtensions", "Yes");
                } else {
                        keys_add_int(request_keys, "MaxRecvDataSegmentLength",
                            isl->isl_max_recv_data_segment_length);
                }
        } else {
                keys_add(request_keys, "HeaderDigest", "None");
                keys_add(request_keys, "DataDigest", "None");
                keys_add_int(request_keys, "MaxRecvDataSegmentLength",
                    isl->isl_max_recv_data_segment_length);
        }

        conn->conn.conn_max_recv_data_segment_length =
            isl->isl_max_recv_data_segment_length;

        keys_add(request_keys, "DefaultTime2Wait", "0");
        keys_add(request_keys, "DefaultTime2Retain", "0");
        keys_add(request_keys, "ErrorRecoveryLevel", "0");
        keys_save_pdu(request_keys, request);
        keys_delete(request_keys);
        request_keys = NULL;
        pdu_send(request);
        pdu_delete(request);
        request = NULL;

        response = login_receive(&conn->conn);
        response_keys = keys_new();
        keys_load_pdu(response_keys, response);
        for (i = 0; i < KEYS_MAX; i++) {
                if (response_keys->keys_names[i] == NULL)
                        break;

                login_negotiate_key(conn,
                    response_keys->keys_names[i], response_keys->keys_values[i]);
        }

        keys_delete(response_keys);
        response_keys = NULL;

        for (;;) {
                bhslr = (struct iscsi_bhs_login_response *)response->pdu_bhs;
                if ((bhslr->bhslr_flags & BHSLR_FLAGS_TRANSIT) != 0)
                        break;

                nrequests++;
                if (nrequests > 5) {
                        log_warnx("received login response "
                            "without the \"T\" flag too many times; giving up");
                        break;
                }

                log_debugx("received login response "
                    "without the \"T\" flag; sending another request");

                pdu_delete(response);

                request = login_new_request(&conn->conn,
                    BHSLR_STAGE_OPERATIONAL_NEGOTIATION);
                pdu_send(request);
                pdu_delete(request);

                response = login_receive(&conn->conn);
        }

        if (login_nsg(response) != BHSLR_STAGE_FULL_FEATURE_PHASE)
                log_warnx("received final login response with wrong NSG 0x%x",
                    login_nsg(response));
        pdu_delete(response);

        log_debugx("operational parameter negotiation done; "
            "transitioning to Full Feature phase");
}

static void
login_send_chap_a(struct connection *conn)
{
        struct pdu *request;
        struct keys *request_keys;

        request = login_new_request(conn, BHSLR_STAGE_SECURITY_NEGOTIATION);
        request_keys = keys_new();
        keys_add(request_keys, "CHAP_A", "5");
        keys_save_pdu(request_keys, request);
        keys_delete(request_keys);
        pdu_send(request);
        pdu_delete(request);
}

static void
login_send_chap_r(struct pdu *response)
{
        struct iscsid_connection *conn;
        struct pdu *request;
        struct keys *request_keys, *response_keys;
        struct rchap *rchap;
        const char *chap_a, *chap_c, *chap_i;
        char *chap_r;
        int error;
        char *mutual_chap_c, *mutual_chap_i;

        /*
         * As in the rest of the initiator, 'request' means
         * 'initiator -> target', and 'response' means 'target -> initiator',
         *
         * So, here the 'response' from the target is the packet that contains
         * CHAP challenge; our CHAP response goes into 'request'.
         */

        conn = (struct iscsid_connection *)response->pdu_connection;

        response_keys = keys_new();
        keys_load_pdu(response_keys, response);

        /*
         * First, compute the response.
         */
        chap_a = keys_find(response_keys, "CHAP_A");
        if (chap_a == NULL)
                log_errx(1, "received CHAP packet without CHAP_A");
        chap_c = keys_find(response_keys, "CHAP_C");
        if (chap_c == NULL)
                log_errx(1, "received CHAP packet without CHAP_C");
        chap_i = keys_find(response_keys, "CHAP_I");
        if (chap_i == NULL)
                log_errx(1, "received CHAP packet without CHAP_I");

        if (strcmp(chap_a, "5") != 0) {
                log_errx(1, "received CHAP packet "
                    "with unsupported CHAP_A \"%s\"", chap_a);
        }

        rchap = rchap_new(conn->conn_conf.isc_secret);
        error = rchap_receive(rchap, chap_i, chap_c);
        if (error != 0) {
                log_errx(1, "received CHAP packet "
                    "with malformed CHAP_I or CHAP_C");
        }
        chap_r = rchap_get_response(rchap);
        rchap_delete(rchap);

        keys_delete(response_keys);

        request = login_new_request(&conn->conn,
            BHSLR_STAGE_SECURITY_NEGOTIATION);
        request_keys = keys_new();
        keys_add(request_keys, "CHAP_N", conn->conn_conf.isc_user);
        keys_add(request_keys, "CHAP_R", chap_r);
        free(chap_r);

        /*
         * If we want mutual authentication, we're expected to send
         * our CHAP_I/CHAP_C now.
         */
        if (conn->conn_conf.isc_mutual_user[0] != '\0') {
                log_debugx("requesting mutual authentication; "
                    "binary challenge size is %zd bytes",
                    sizeof(conn->conn_mutual_chap->chap_challenge));

                assert(conn->conn_mutual_chap == NULL);
                conn->conn_mutual_chap = chap_new();
                mutual_chap_i = chap_get_id(conn->conn_mutual_chap);
                mutual_chap_c = chap_get_challenge(conn->conn_mutual_chap);
                keys_add(request_keys, "CHAP_I", mutual_chap_i);
                keys_add(request_keys, "CHAP_C", mutual_chap_c);
                free(mutual_chap_i);
                free(mutual_chap_c);
        }

        keys_save_pdu(request_keys, request);
        keys_delete(request_keys);
        pdu_send(request);
        pdu_delete(request);
}

static void
login_verify_mutual(const struct pdu *response)
{
        struct iscsid_connection *conn;
        struct keys *response_keys;
        const char *chap_n, *chap_r;
        int error;

        conn = (struct iscsid_connection *)response->pdu_connection;

        response_keys = keys_new();
        keys_load_pdu(response_keys, response);

        chap_n = keys_find(response_keys, "CHAP_N");
        if (chap_n == NULL)
                log_errx(1, "received CHAP Response PDU without CHAP_N");
        chap_r = keys_find(response_keys, "CHAP_R");
        if (chap_r == NULL)
                log_errx(1, "received CHAP Response PDU without CHAP_R");

        error = chap_receive(conn->conn_mutual_chap, chap_r);
        if (error != 0)
                log_errx(1, "received CHAP Response PDU with invalid CHAP_R");

        if (strcmp(chap_n, conn->conn_conf.isc_mutual_user) != 0) {
                fail(&conn->conn, "Mutual CHAP failed");
                log_errx(1, "mutual CHAP authentication failed: wrong user");
        }

        error = chap_authenticate(conn->conn_mutual_chap,
            conn->conn_conf.isc_mutual_secret);
        if (error != 0) {
                fail(&conn->conn, "Mutual CHAP failed");
                log_errx(1, "mutual CHAP authentication failed: wrong secret");
        }

        keys_delete(response_keys);
        chap_delete(conn->conn_mutual_chap);
        conn->conn_mutual_chap = NULL;

        log_debugx("mutual CHAP authentication succeeded");
}

static void
login_chap(struct iscsid_connection *conn)
{
        struct pdu *response;

        log_debugx("beginning CHAP authentication; sending CHAP_A");
        login_send_chap_a(&conn->conn);

        log_debugx("waiting for CHAP_A/CHAP_C/CHAP_I");
        response = login_receive(&conn->conn);

        log_debugx("sending CHAP_N/CHAP_R");
        login_send_chap_r(response);
        pdu_delete(response);

        /*
         * XXX: Make sure this is not susceptible to MITM.
         */

        log_debugx("waiting for CHAP result");
        response = login_receive(&conn->conn);
        if (conn->conn_conf.isc_mutual_user[0] != '\0')
                login_verify_mutual(response);
        pdu_delete(response);

        log_debugx("CHAP authentication done");
}

void
login(struct iscsid_connection *conn)
{
        struct pdu *request, *response;
        struct keys *request_keys, *response_keys;
        struct iscsi_bhs_login_response *bhslr2;
        const char *auth_method;
        int i;

        log_debugx("beginning Login phase; sending Login PDU");
        request = login_new_request(&conn->conn,
            BHSLR_STAGE_SECURITY_NEGOTIATION);
        request_keys = keys_new();
        if (conn->conn_conf.isc_mutual_user[0] != '\0') {
                keys_add(request_keys, "AuthMethod", "CHAP");
        } else if (conn->conn_conf.isc_user[0] != '\0') {
                /*
                 * Give target a chance to skip authentication if it
                 * doesn't feel like it.
                 *
                 * None is first, CHAP second; this is to work around
                 * what seems to be LIO (Linux target) bug: otherwise,
                 * if target is configured with no authentication,
                 * and we are configured to authenticate, the target
                 * will erroneously respond with AuthMethod=CHAP
                 * instead of AuthMethod=None, and will subsequently
                 * fail the connection.  This usually happens with
                 * Discovery sessions, which default to no authentication.
                 */
                keys_add(request_keys, "AuthMethod", "None,CHAP");
        } else {
                keys_add(request_keys, "AuthMethod", "None");
        }
        keys_add(request_keys, "InitiatorName",
            conn->conn_conf.isc_initiator);
        if (conn->conn_conf.isc_initiator_alias[0] != '\0') {
                keys_add(request_keys, "InitiatorAlias",
                    conn->conn_conf.isc_initiator_alias);
        }
        if (conn->conn_conf.isc_discovery == 0) {
                keys_add(request_keys, "SessionType", "Normal");
                keys_add(request_keys,
                    "TargetName", conn->conn_conf.isc_target);
        } else {
                keys_add(request_keys, "SessionType", "Discovery");
        }
        keys_save_pdu(request_keys, request);
        keys_delete(request_keys);
        pdu_send(request);
        pdu_delete(request);

        response = login_receive(&conn->conn);

        response_keys = keys_new();
        keys_load_pdu(response_keys, response);

        for (i = 0; i < KEYS_MAX; i++) {
                if (response_keys->keys_names[i] == NULL)
                        break;

                /*
                 * Not interested in AuthMethod at this point; we only need
                 * to parse things such as TargetAlias.
                 *
                 * XXX: This is somewhat ugly.  We should have a way to apply
                 *      all the keys to the session and use that by default
                 *      instead of discarding them.
                 */
                if (strcmp(response_keys->keys_names[i], "AuthMethod") == 0)
                        continue;

                login_negotiate_key(conn,
                    response_keys->keys_names[i], response_keys->keys_values[i]);
        }

        bhslr2 = (struct iscsi_bhs_login_response *)response->pdu_bhs;
        if ((bhslr2->bhslr_flags & BHSLR_FLAGS_TRANSIT) != 0 &&
            login_nsg(response) == BHSLR_STAGE_OPERATIONAL_NEGOTIATION) {
                if (conn->conn_conf.isc_mutual_user[0] != '\0') {
                        log_errx(1, "target requested transition "
                            "to operational parameter negotiation, "
                            "but we require mutual CHAP");
                }

                log_debugx("target requested transition "
                    "to operational parameter negotiation");
                keys_delete(response_keys);
                pdu_delete(response);
                login_negotiate(conn);
                return;
        }

        auth_method = keys_find(response_keys, "AuthMethod");
        if (auth_method == NULL)
                log_errx(1, "received response without AuthMethod");
        if (strcmp(auth_method, "None") == 0) {
                if (conn->conn_conf.isc_mutual_user[0] != '\0') {
                        log_errx(1, "target does not require authantication, "
                            "but we require mutual CHAP");
                }

                log_debugx("target does not require authentication");
                keys_delete(response_keys);
                pdu_delete(response);
                login_negotiate(conn);
                return;
        }

        if (strcmp(auth_method, "CHAP") != 0) {
                fail(&conn->conn, "Unsupported AuthMethod");
                log_errx(1, "received response "
                    "with unsupported AuthMethod \"%s\"", auth_method);
        }

        if (conn->conn_conf.isc_user[0] == '\0' ||
            conn->conn_conf.isc_secret[0] == '\0') {
                fail(&conn->conn, "Authentication required");
                log_errx(1, "target requests CHAP authentication, but we don't "
                    "have user and secret");
        }

        keys_delete(response_keys);
        response_keys = NULL;
        pdu_delete(response);
        response = NULL;

        login_chap(conn);
        login_negotiate(conn);
}