/* Copyright (c) 2004-2007, Sara Golemon <sarag@libssh2.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms,
 * with or without modification, are permitted provided
 * that the following conditions are met:
 *
 *   Redistributions of source code must retain the above
 *   copyright notice, this list of conditions and the
 *   following disclaimer.
 *
 *   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.
 *
 *   Neither the name of the copyright holder nor the names
 *   of any other contributors may be used to endorse or
 *   promote products derived from this software without
 *   specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT OWNER 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 "libssh2_priv.h"
#include "libssh2_publickey.h"

#define LIBSSH2_PUBLICKEY_VERSION               2

/* Numericised response codes -- Not IETF standard, just a local representation */
#define LIBSSH2_PUBLICKEY_RESPONSE_STATUS       0
#define LIBSSH2_PUBLICKEY_RESPONSE_VERSION      1
#define LIBSSH2_PUBLICKEY_RESPONSE_PUBLICKEY    2

typedef struct _LIBSSH2_PUBLICKEY_CODE_LIST {
    int code;
    const char *name;
    int name_len;
} LIBSSH2_PUBLICKEY_CODE_LIST;

static const LIBSSH2_PUBLICKEY_CODE_LIST libssh2_publickey_response_codes[] = {
    { LIBSSH2_PUBLICKEY_RESPONSE_STATUS, "status", sizeof("status") - 1 },
    { LIBSSH2_PUBLICKEY_RESPONSE_VERSION, "version", sizeof("version") - 1 },
    { LIBSSH2_PUBLICKEY_RESPONSE_PUBLICKEY, "publickey", sizeof("publickey") - 1 },
    { 0, NULL, 0 }
};

/* PUBLICKEY status codes -- IETF defined */
#define LIBSSH2_PUBLICKEY_SUCCESS               0
#define LIBSSH2_PUBLICKEY_ACCESS_DENIED         1
#define LIBSSH2_PUBLICKEY_STORAGE_EXCEEDED      2
#define LIBSSH2_PUBLICKEY_VERSION_NOT_SUPPORTED 3
#define LIBSSH2_PUBLICKEY_KEY_NOT_FOUND         4
#define LIBSSH2_PUBLICKEY_KEY_NOT_SUPPORTED     5
#define LIBSSH2_PUBLICKEY_KEY_ALREADY_PRESENT   6
#define LIBSSH2_PUBLICKEY_GENERAL_FAILURE       7
#define LIBSSH2_PUBLICKEY_REQUEST_NOT_SUPPORTED 8

#define LIBSSH2_PUBLICKEY_STATUS_CODE_MAX       8

static const LIBSSH2_PUBLICKEY_CODE_LIST libssh2_publickey_status_codes[] = {
    { LIBSSH2_PUBLICKEY_SUCCESS,                "success",                  sizeof("success") - 1 },
    { LIBSSH2_PUBLICKEY_ACCESS_DENIED,          "access denied",            sizeof("access denied") - 1 },
    { LIBSSH2_PUBLICKEY_STORAGE_EXCEEDED,       "storage exceeded",         sizeof("storage exceeded") - 1 },
    { LIBSSH2_PUBLICKEY_VERSION_NOT_SUPPORTED,  "version not supported",    sizeof("version not supported") - 1 },
    { LIBSSH2_PUBLICKEY_KEY_NOT_FOUND,          "key not found",            sizeof("key not found") - 1 },
    { LIBSSH2_PUBLICKEY_KEY_NOT_SUPPORTED,      "key not supported",        sizeof("key not supported") - 1 },
    { LIBSSH2_PUBLICKEY_KEY_ALREADY_PRESENT,    "key already present",      sizeof("key already present") - 1 },
    { LIBSSH2_PUBLICKEY_GENERAL_FAILURE,        "general failure",          sizeof("general failure") - 1 },
    { LIBSSH2_PUBLICKEY_REQUEST_NOT_SUPPORTED,  "request not supported",    sizeof("request not supported") - 1 },
    { 0, NULL, 0 }
};

/* {{{ libssh2_publickey_status_error
 * Format an error message from a status code
 */
#define LIBSSH2_PUBLICKEY_STATUS_TEXT_START     "Publickey Subsystem Error: \""
#define LIBSSH2_PUBLICKEY_STATUS_TEXT_MID       "\" Server Resports: \""
#define LIBSSH2_PUBLICKEY_STATUS_TEXT_END       "\""
static void
libssh2_publickey_status_error(const LIBSSH2_PUBLICKEY *pkey, LIBSSH2_SESSION *session, int status,
                               const unsigned char *message, int message_len)
{
    const char *status_text;
    int status_text_len;
    char *m, *s;
    int m_len;

    /* GENERAL_FAILURE got remapped between version 1 and 2 */
    if (status == 6 && pkey && pkey->version == 1) {
        status = 7;
    }

    if (status < 0 || status > LIBSSH2_PUBLICKEY_STATUS_CODE_MAX) {
        status_text = "unknown";
        status_text_len = sizeof("unknown") - 1;
    } else {
        status_text = libssh2_publickey_status_codes[status].name;
        status_text_len = libssh2_publickey_status_codes[status].name_len;
    }

    m_len = (sizeof(LIBSSH2_PUBLICKEY_STATUS_TEXT_START) - 1) + status_text_len + 
            (sizeof(LIBSSH2_PUBLICKEY_STATUS_TEXT_MID) - 1) + message_len +
            (sizeof(LIBSSH2_PUBLICKEY_STATUS_TEXT_END) - 1);
    m = LIBSSH2_ALLOC(session, m_len + 1);
    if (!m) {
        libssh2_error(session, LIBSSH2_ERROR_ALLOC, "Unable to allocate memory for status message", 0);
        return;
    }
    s = m;
    memcpy(s, LIBSSH2_PUBLICKEY_STATUS_TEXT_START, sizeof(LIBSSH2_PUBLICKEY_STATUS_TEXT_START) - 1);
                                                            s += sizeof(LIBSSH2_PUBLICKEY_STATUS_TEXT_START) - 1;
    memcpy(s, status_text, status_text_len);                s += status_text_len;
    memcpy(s, LIBSSH2_PUBLICKEY_STATUS_TEXT_MID, sizeof(LIBSSH2_PUBLICKEY_STATUS_TEXT_MID) - 1);
                                                            s += sizeof(LIBSSH2_PUBLICKEY_STATUS_TEXT_MID) - 1;
    memcpy(s, message, message_len);                        s += message_len;
    memcpy(s, LIBSSH2_PUBLICKEY_STATUS_TEXT_END, sizeof(LIBSSH2_PUBLICKEY_STATUS_TEXT_END) - 1);
                                                            s += sizeof(LIBSSH2_PUBLICKEY_STATUS_TEXT_END);
    libssh2_error(session, LIBSSH2_ERROR_PUBLICKEY_PROTOCOL, m, 1);
}
/* }}} */

/* {{{ libssh2_publickey_packet_receive
 * Read a packet from the subsystem
 */
static int
libssh2_publickey_packet_receive(LIBSSH2_PUBLICKEY *pkey, unsigned char **data, unsigned long *data_len)
{
    LIBSSH2_CHANNEL *channel = pkey->channel;
    LIBSSH2_SESSION *session = channel->session;
    unsigned char buffer[4];
    int rc;

    if (pkey->receive_state == libssh2_NB_state_idle) {
        rc = libssh2_channel_read_ex(channel, 0, (char *)buffer, 4);
        if (rc == PACKET_EAGAIN) {
            return PACKET_EAGAIN;
        }
        else if (rc != 4) {
            libssh2_error(session, LIBSSH2_ERROR_PUBLICKEY_PROTOCOL, "Invalid response from publickey subsystem", 0);
            return -1;
        }

        pkey->receive_packet_len = libssh2_ntohu32(buffer);
        pkey->receive_packet = LIBSSH2_ALLOC(session, pkey->receive_packet_len);
        if (!pkey->receive_packet) {
            libssh2_error(session, LIBSSH2_ERROR_ALLOC, "Unable to allocate publickey response buffer", 0);
            return -1;
        }
        
        pkey->receive_state = libssh2_NB_state_sent;
    }

    if (pkey->receive_state == libssh2_NB_state_sent) {
        rc = libssh2_channel_read_ex(channel, 0, (char *)pkey->receive_packet, pkey->receive_packet_len);
        if (rc == PACKET_EAGAIN) {
            return PACKET_EAGAIN;
        }
        else if (rc != pkey->receive_packet_len) {
            libssh2_error(session, LIBSSH2_ERROR_SOCKET_TIMEOUT, "Timeout waiting for publickey subsystem response packet", 0);
            LIBSSH2_FREE(session, pkey->receive_packet);
            pkey->receive_packet = NULL;
            pkey->receive_state = libssh2_NB_state_idle;
            return -1;
        }

        *data = pkey->receive_packet;
        *data_len = pkey->receive_packet_len;
    }
    
    pkey->receive_state = libssh2_NB_state_idle;

    return 0;
}
/* }}} */

/* {{{ libssh2_publickey_response_id
 * Translate a string response name to a numeric code
 * Data will be incremented by 4 + response_len on success only
 */
static int libssh2_publickey_response_id(unsigned char **pdata, int data_len)
{
    unsigned long response_len;
    unsigned char *data = *pdata;
    const LIBSSH2_PUBLICKEY_CODE_LIST *codes = libssh2_publickey_response_codes;

    if (data_len < 4) {
        /* Malformed response */
        return -1;
    }
    response_len = libssh2_ntohu32(data);           data += 4;          data_len -= 4;
    if (data_len < response_len) {
        /* Malformed response */
        return -1;
    }

    while (codes->name) {
        if (codes->name_len == response_len &&
            strncmp(codes->name, (char *)data, response_len) == 0) {
            *pdata = data + response_len;
            return codes->code;
        }
        codes++;
    }

    return -1;
}
/* }}} */

/* {{{ libssh2_publickey_response_success
 * Generic helper routine to wait for success response and nothing else
 */
static int libssh2_publickey_response_success(LIBSSH2_PUBLICKEY *pkey)
{
    LIBSSH2_SESSION *session = pkey->channel->session;
    unsigned char *data, *s;
    unsigned long data_len;
    int response;
    int rc;

    while (1) {
        rc = libssh2_publickey_packet_receive(pkey, &data, &data_len);
        if (rc == PACKET_EAGAIN) {
            return PACKET_EAGAIN;
        }
        else if (rc) {
            libssh2_error(session, LIBSSH2_ERROR_SOCKET_TIMEOUT, "Timeout waiting for response from publickey subsystem", 0);
            return -1;
        }

        s = data;
        if ((response = libssh2_publickey_response_id(&s, data_len)) < 0) {
            libssh2_error(session, LIBSSH2_ERROR_PUBLICKEY_PROTOCOL, "Invalid publickey subsystem response code", 0);
            LIBSSH2_FREE(session, data);
            return -1;
        }

        switch (response) {
            case LIBSSH2_PUBLICKEY_RESPONSE_STATUS:
            /* Error, or processing complete */
            {
                unsigned long status, descr_len, lang_len;
                unsigned char *descr, *lang;
                
                status = libssh2_ntohu32(s);                    s += 4;
                descr_len = libssh2_ntohu32(s);                 s += 4;
                descr = s;                                      s += descr_len;
                lang_len = libssh2_ntohu32(s);                  s += 4;
                lang = s;                                       s += lang_len;

                if (s > data + data_len) {
                    libssh2_error(session, LIBSSH2_ERROR_PUBLICKEY_PROTOCOL, "Malformed publickey subsystem packet", 0);
                    LIBSSH2_FREE(session, data);
                    return -1;
                }

                if (status == LIBSSH2_PUBLICKEY_SUCCESS) {
                    LIBSSH2_FREE(session, data);
                    return 0;
                }

                libssh2_publickey_status_error(pkey, session, status, descr, descr_len);
                LIBSSH2_FREE(session, data);
                return -1;
            }
            default:
                /* Unknown/Unexpected */
                libssh2_error(session, LIBSSH2_ERROR_PUBLICKEY_PROTOCOL, "Unexpected publickey subsystem response, ignoring", 0);
                LIBSSH2_FREE(session, data);
                data = NULL;
        }
    }
    /* never reached, but include `return` to silence compiler warnings */
    return -1;
}
/* }}} */


/* *****************
   * Publickey API *
   ***************** */

/* {{{ libssh2_publickey_init
 * Startup the publickey subsystem
 */
LIBSSH2_API LIBSSH2_PUBLICKEY *libssh2_publickey_init(LIBSSH2_SESSION *session)
{
    /* 19 = packet_len(4) + version_len(4) + "version"(7) + version_num(4) */
    unsigned char buffer[19];
    unsigned char *s;
    int response;
    int rc;

    if (session->pkeyInit_state == libssh2_NB_state_idle) {
        session->pkeyInit_data = NULL;
        session->pkeyInit_pkey = NULL;
        session->pkeyInit_channel = NULL;
        
        _libssh2_debug(session, LIBSSH2_DBG_PUBLICKEY, "Initializing publickey subsystem");
        
        session->pkeyInit_state = libssh2_NB_state_allocated;
    }

    if (session->pkeyInit_state == libssh2_NB_state_allocated) {
        do {
            session->pkeyInit_channel = libssh2_channel_open_ex(session, "session", sizeof("session") - 1,
                                                                LIBSSH2_CHANNEL_WINDOW_DEFAULT, LIBSSH2_CHANNEL_PACKET_DEFAULT,
                                                                NULL, 0);
            if (!session->pkeyInit_channel && (libssh2_session_last_errno(session) == LIBSSH2_ERROR_EAGAIN)) {
                /* The error state is already set, so leave it */
                libssh2_error(session, LIBSSH2_ERROR_EAGAIN, "Would block to startup channel", 0);
                return NULL;
            }
            else if (!session->pkeyInit_channel && (libssh2_session_last_errno(session) != LIBSSH2_ERROR_EAGAIN)) {
                libssh2_error(session, LIBSSH2_ERROR_CHANNEL_FAILURE, "Unable to startup channel", 0);
                goto err_exit;
            }
        } while (!session->pkeyInit_channel);
        
        session->pkeyInit_state = libssh2_NB_state_sent;
    }
    
    if (session->pkeyInit_state == libssh2_NB_state_sent) {
        rc = libssh2_channel_process_startup(session->pkeyInit_channel, "subsystem", sizeof("subsystem") - 1,
                                             "publickey", strlen("publickey"));
        if (rc == PACKET_EAGAIN) {
            libssh2_error(session, LIBSSH2_ERROR_EAGAIN, "Would block starting publickkey subsystem", 0);
            return NULL;
        }
        else if (rc) {
            libssh2_error(session, LIBSSH2_ERROR_CHANNEL_FAILURE, "Unable to request publickey subsystem", 0);
            goto err_exit;
        }
        
        session->pkeyInit_state = libssh2_NB_state_sent1;
    }

    if (session->pkeyInit_state == libssh2_NB_state_sent1) {
        rc = libssh2_channel_handle_extended_data2(session->pkeyInit_channel, LIBSSH2_CHANNEL_EXTENDED_DATA_IGNORE);
        if (rc == PACKET_EAGAIN) {
            libssh2_error(session, LIBSSH2_ERROR_EAGAIN, "Would block starting publickkey subsystem", 0);
            return NULL;
        }

        session->pkeyInit_pkey = LIBSSH2_ALLOC(session, sizeof(LIBSSH2_PUBLICKEY));
        if (!session->pkeyInit_pkey) {
            libssh2_error(session, LIBSSH2_ERROR_ALLOC, "Unable to allocate a new publickey structure", 0);
            goto err_exit;
        }
        memset(session->pkeyInit_pkey, 0, sizeof(LIBSSH2_PUBLICKEY));
        session->pkeyInit_pkey->channel = session->pkeyInit_channel;
        session->pkeyInit_pkey->version = 0;

        s = buffer;
        libssh2_htonu32(s, 4 + (sizeof("version") - 1) + 4);    s += 4;
        libssh2_htonu32(s, sizeof("version") - 1);              s += 4;
        memcpy(s, "version", sizeof("version") - 1);            s += sizeof("version") - 1;
        libssh2_htonu32(s, LIBSSH2_PUBLICKEY_VERSION);          s += 4;

        _libssh2_debug(session, LIBSSH2_DBG_PUBLICKEY, "Sending publickey version packet advertising version %d support",
                       (int)LIBSSH2_PUBLICKEY_VERSION);
        
        session->pkeyInit_state = libssh2_NB_state_sent2;
    }
    
    if (session->pkeyInit_state == libssh2_NB_state_sent2) {
        rc = libssh2_channel_write_ex(session->pkeyInit_channel, 0, (char*)buffer, (s - buffer));
        if (rc == PACKET_EAGAIN) {
            libssh2_error(session, LIBSSH2_ERROR_EAGAIN, "Would block sending publickkey version packet", 0);
            return NULL;
        }
        else if ((s - buffer) != rc) {
            libssh2_error(session, LIBSSH2_ERROR_SOCKET_SEND, "Unable to send publickey version packet", 0);
            goto err_exit;
        }
        
        session->pkeyInit_state = libssh2_NB_state_sent3;
    }
    
    if (session->pkeyInit_state == libssh2_NB_state_sent3) {
        while (1) {
            rc = libssh2_publickey_packet_receive(session->pkeyInit_pkey, &session->pkeyInit_data, &session->pkeyInit_data_len);
            if (rc == PACKET_EAGAIN) {
                libssh2_error(session, LIBSSH2_ERROR_EAGAIN, "Would block waiting for response from publickey subsystem", 0);
                return NULL;
            }
            else if (rc) {
                libssh2_error(session, LIBSSH2_ERROR_SOCKET_TIMEOUT, "Timeout waiting for response from publickey subsystem", 0);
                goto err_exit;
            }

            s = session->pkeyInit_data;
            if ((response = libssh2_publickey_response_id(&s, session->pkeyInit_data_len)) < 0) {
                libssh2_error(session, LIBSSH2_ERROR_PUBLICKEY_PROTOCOL, "Invalid publickey subsystem response code", 0);
                goto err_exit;
            }

            switch (response) {
                case LIBSSH2_PUBLICKEY_RESPONSE_STATUS:
                    /* Error */
                    {
                        unsigned long status, descr_len, lang_len;
                        unsigned char *descr, *lang;
                        
                        status = libssh2_ntohu32(s);                    s += 4;
                        descr_len = libssh2_ntohu32(s);                 s += 4;
                        descr = s;                                      s += descr_len;
                        lang_len = libssh2_ntohu32(s);                  s += 4;
                        lang = s;                                       s += lang_len;

                        if (s > session->pkeyInit_data + session->pkeyInit_data_len) {
                            libssh2_error(session, LIBSSH2_ERROR_PUBLICKEY_PROTOCOL, "Malformed publickey subsystem packet", 0);
                            goto err_exit;
                        }

                        libssh2_publickey_status_error(NULL, session, status, descr, descr_len);
                        goto err_exit;
                    }
                    
                case LIBSSH2_PUBLICKEY_RESPONSE_VERSION:
                    /* What we want */
                    session->pkeyInit_pkey->version = libssh2_ntohu32(s);
                    if (session->pkeyInit_pkey->version > LIBSSH2_PUBLICKEY_VERSION) {
                        _libssh2_debug(session, LIBSSH2_DBG_PUBLICKEY, "Truncating remote publickey version from %lu",
                                       session->pkeyInit_pkey->version);
                        session->pkeyInit_pkey->version = LIBSSH2_PUBLICKEY_VERSION;
                    }
                    _libssh2_debug(session, LIBSSH2_DBG_PUBLICKEY, "Enabling publickey subsystem version %lu",
                                   session->pkeyInit_pkey->version);
                    LIBSSH2_FREE(session, session->pkeyInit_data);
                    session->pkeyInit_data = NULL;
                    session->pkeyInit_state = libssh2_NB_state_idle;
                    return session->pkeyInit_pkey;
                    
                default:
                    /* Unknown/Unexpected */
                    libssh2_error(session, LIBSSH2_ERROR_PUBLICKEY_PROTOCOL,
                                  "Unexpected publickey subsystem response, ignoring", 0);
                    LIBSSH2_FREE(session, session->pkeyInit_data);
                    session->pkeyInit_data = NULL;
            }
        }
    }

    /* Never reached except by direct goto */
 err_exit:
    session->pkeyInit_state = libssh2_NB_state_sent4;
    if (session->pkeyInit_channel) {
        rc = libssh2_channel_close(session->pkeyInit_channel);
        if (rc == PACKET_EAGAIN) {
            libssh2_error(session, LIBSSH2_ERROR_EAGAIN, "Would block closing channel", 0);
            return NULL;
        }
    }
    if (session->pkeyInit_pkey) {
        LIBSSH2_FREE(session, session->pkeyInit_pkey);
        session->pkeyInit_pkey = NULL;
    }
    if (session->pkeyInit_data) {
        LIBSSH2_FREE(session, session->pkeyInit_data);
        session->pkeyInit_data = NULL;
    }
    session->pkeyInit_state = libssh2_NB_state_idle;
    return NULL;
}
/* }}} */

/* {{{ libssh2_publickey_add_ex
 * Add a new public key entry
 */
LIBSSH2_API int 
libssh2_publickey_add_ex(LIBSSH2_PUBLICKEY *pkey, const unsigned char *name, unsigned long name_len,
                         const unsigned char *blob, unsigned long blob_len, char overwrite, unsigned long num_attrs,
                         const libssh2_publickey_attribute attrs[])
{
    LIBSSH2_CHANNEL *channel = pkey->channel;
    LIBSSH2_SESSION *session = channel->session;
    /*  19 = packet_len(4) + add_len(4) + "add"(3) + name_len(4) + {name} blob_len(4) + {blob} */
    unsigned long i, packet_len = 19 + name_len + blob_len;
    unsigned char *comment = NULL;
    unsigned long comment_len = 0;
    int rc;

    if (pkey->add_state == libssh2_NB_state_idle) {
        pkey->add_packet = NULL;
        
        _libssh2_debug(session, LIBSSH2_DBG_PUBLICKEY, "Adding %s publickey", name);

        if (pkey->version == 1) {
            for(i = 0; i < num_attrs; i++) {
                /* Search for a comment attribute */
                if (attrs[i].name_len == (sizeof("comment") - 1) &&
                    strncmp(attrs[i].name, "comment", sizeof("comment") - 1) == 0) {
                    comment = (unsigned char *)attrs[i].value;
                    comment_len = attrs[i].value_len;
                    break;
                }
            }
            packet_len += 4 + comment_len;
        } else {
            packet_len += 5; /* overwrite(1) + attribute_count(4) */
            for(i = 0; i < num_attrs; i++) {
                packet_len += 9 + attrs[i].name_len + attrs[i].value_len;
                /* name_len(4) + value_len(4) + mandatory(1) */
            }
        }

        pkey->add_packet = LIBSSH2_ALLOC(session, packet_len);
        if (!pkey->add_packet) {
            libssh2_error(session, LIBSSH2_ERROR_ALLOC, "Unable to allocate memory for publickey \"add\" packet", 0);
            return -1;
        }

        pkey->add_s = pkey->add_packet;
        libssh2_htonu32(pkey->add_s, packet_len - 4);                     pkey->add_s += 4;
        libssh2_htonu32(pkey->add_s, sizeof("add") - 1);                  pkey->add_s += 4;
        memcpy(pkey->add_s, "add", sizeof("add") - 1);                    pkey->add_s += sizeof("add") - 1;
        if (pkey->version == 1) {
            libssh2_htonu32(pkey->add_s, comment_len);                    pkey->add_s += 4;
            if (comment) {
                memcpy(pkey->add_s, comment, comment_len);                pkey->add_s += comment_len;
            }

            libssh2_htonu32(pkey->add_s, name_len);                       pkey->add_s += 4;
            memcpy(pkey->add_s, name, name_len);                          pkey->add_s += name_len;
            libssh2_htonu32(pkey->add_s, blob_len);                       pkey->add_s += 4;
            memcpy(pkey->add_s, blob, blob_len);                          pkey->add_s += blob_len;
        } else {
            /* Version == 2 */

            libssh2_htonu32(pkey->add_s, name_len);                       pkey->add_s += 4;
            memcpy(pkey->add_s, name, name_len);                          pkey->add_s += name_len;
            libssh2_htonu32(pkey->add_s, blob_len);                       pkey->add_s += 4;
            memcpy(pkey->add_s, blob, blob_len);                          pkey->add_s += blob_len;
            *(pkey->add_s++) = overwrite ? 0x01 : 0;
            libssh2_htonu32(pkey->add_s, num_attrs);                      pkey->add_s += 4;
            for(i = 0; i < num_attrs; i++) {
                libssh2_htonu32(pkey->add_s, attrs[i].name_len);          pkey->add_s += 4;
                memcpy(pkey->add_s, attrs[i].name, attrs[i].name_len);    pkey->add_s += attrs[i].name_len;
                libssh2_htonu32(pkey->add_s, attrs[i].value_len);         pkey->add_s += 4;
                memcpy(pkey->add_s, attrs[i].value, attrs[i].value_len);  pkey->add_s += attrs[i].value_len;
                *(pkey->add_s++) = attrs[i].mandatory ? 0x01 : 0;
            }
        }

        _libssh2_debug(session, LIBSSH2_DBG_PUBLICKEY, "Sending publickey \"add\" packet: type=%s blob_len=%ld num_attrs=%ld",
                       name, blob_len, num_attrs);
        
        pkey->add_state = libssh2_NB_state_created;
    }
    
    if (pkey->add_state == libssh2_NB_state_created) {
        rc = libssh2_channel_write_ex(channel, 0, (char *)pkey->add_packet, (pkey->add_s - pkey->add_packet));
        if (rc == PACKET_EAGAIN) {
            return PACKET_EAGAIN;
        }
        else if ((pkey->add_s - pkey->add_packet) != rc) {
            libssh2_error(session, LIBSSH2_ERROR_SOCKET_SEND, "Unable to send publickey add packet", 0);
            LIBSSH2_FREE(session, pkey->add_packet);
            pkey->add_packet = NULL;
            return -1;
        }
        LIBSSH2_FREE(session, pkey->add_packet);
        pkey->add_packet = NULL;
        
        pkey->add_state = libssh2_NB_state_sent;
    }

    rc = libssh2_publickey_response_success(pkey);
    if (rc == PACKET_EAGAIN) {
        return PACKET_EAGAIN;
    }
    
    pkey->add_state = libssh2_NB_state_idle;
    
    return rc;
}
/* }}} */

/* {{{ libssh2_publickey_remove_ex
 * Remove an existing publickey so that authentication can no longer be performed using it
 */
LIBSSH2_API int 
libssh2_publickey_remove_ex(LIBSSH2_PUBLICKEY *pkey, const unsigned char *name, unsigned long name_len,
                            const unsigned char *blob, unsigned long blob_len)
{
    LIBSSH2_CHANNEL *channel = pkey->channel;
    LIBSSH2_SESSION *session = channel->session;
    /* 22 = packet_len(4) + remove_len(4) + "remove"(6) + name_len(4) + {name} + blob_len(4) + {blob} */
    unsigned long packet_len = 22 + name_len + blob_len;
    int rc;

    if (pkey->remove_state == libssh2_NB_state_idle) {
        pkey->remove_packet = NULL;
        
        pkey->remove_packet = LIBSSH2_ALLOC(session, packet_len);
        if (!pkey->remove_packet) {
            libssh2_error(session, LIBSSH2_ERROR_ALLOC, "Unable to allocate memory for publickey \"remove\" packet", 0);
            return -1;
        }

        pkey->remove_s = pkey->remove_packet;
        libssh2_htonu32(pkey->remove_s, packet_len - 4);                         pkey->remove_s += 4;
        libssh2_htonu32(pkey->remove_s, sizeof("remove") - 1);                   pkey->remove_s += 4;
        memcpy(pkey->remove_s, "remove", sizeof("remove") - 1);                  pkey->remove_s += sizeof("remove") - 1;
        libssh2_htonu32(pkey->remove_s, name_len);                               pkey->remove_s += 4;
        memcpy(pkey->remove_s, name, name_len);                                  pkey->remove_s += name_len;
        libssh2_htonu32(pkey->remove_s, blob_len);                               pkey->remove_s += 4;
        memcpy(pkey->remove_s, blob, blob_len);                                  pkey->remove_s += blob_len;

        _libssh2_debug(session, LIBSSH2_DBG_PUBLICKEY, "Sending publickey \"remove\" packet: type=%s blob_len=%ld", name, blob_len);
        
        pkey->remove_state = libssh2_NB_state_created;
    }
    
    if (pkey->remove_state == libssh2_NB_state_created) {
        rc = libssh2_channel_write_ex(channel, 0, (char *)pkey->remove_packet, (pkey->remove_s - pkey->remove_packet));
        if (rc == PACKET_EAGAIN) {
            return PACKET_EAGAIN;
        }
        else if ((pkey->remove_s - pkey->remove_packet) != rc) {
            libssh2_error(session, LIBSSH2_ERROR_SOCKET_SEND, "Unable to send publickey remove packet", 0);
            LIBSSH2_FREE(session, pkey->remove_packet);
            pkey->remove_packet = NULL;
            pkey->remove_state = libssh2_NB_state_idle;
            return -1;
        }
        LIBSSH2_FREE(session, pkey->remove_packet);
        pkey->remove_packet = NULL;
        
        pkey->remove_state = libssh2_NB_state_sent;
    }

    rc = libssh2_publickey_response_success(pkey);
    if (rc == PACKET_EAGAIN) {
        return PACKET_EAGAIN;
    }
    
    pkey->remove_state = libssh2_NB_state_idle;
    
    return rc;
}
/* }}} */

/* {{{ libssh2_publickey_list_fetch
 * Fetch a list of supported public key from a server
 */
LIBSSH2_API int
libssh2_publickey_list_fetch(LIBSSH2_PUBLICKEY *pkey, unsigned long *num_keys, libssh2_publickey_list **pkey_list)
{
    LIBSSH2_CHANNEL *channel = pkey->channel;
    LIBSSH2_SESSION *session = channel->session;
    libssh2_publickey_list *list = NULL;
    unsigned long buffer_len = 12, keys = 0, max_keys = 0, i;
    /* 12 = packet_len(4) + list_len(4) + "list"(4) */
    int response;
    int rc;

    if (pkey->listFetch_state == libssh2_NB_state_idle) {
        pkey->listFetch_data = NULL;
        
        pkey->listFetch_s = pkey->listFetch_buffer;
        libssh2_htonu32(pkey->listFetch_s, buffer_len - 4);                 pkey->listFetch_s += 4;
        libssh2_htonu32(pkey->listFetch_s, sizeof("list") - 1);             pkey->listFetch_s += 4;
        memcpy(pkey->listFetch_s, "list", sizeof("list") - 1);              pkey->listFetch_s += sizeof("list") - 1;

        _libssh2_debug(session, LIBSSH2_DBG_PUBLICKEY, "Sending publickey \"list\" packet");
        
        pkey->listFetch_state = libssh2_NB_state_created;
    }
    
    if (pkey->listFetch_state == libssh2_NB_state_created) {
        rc = libssh2_channel_write_ex(channel, 0, (char *)pkey->listFetch_buffer, (pkey->listFetch_s - pkey->listFetch_buffer));
        if (rc == PACKET_EAGAIN) {
            return PACKET_EAGAIN;
        }
        else if ((pkey->listFetch_s - pkey->listFetch_buffer) != rc) {
            libssh2_error(session, LIBSSH2_ERROR_SOCKET_SEND, "Unable to send publickey list packet", 0);
            pkey->listFetch_state = libssh2_NB_state_idle;
            return -1;
        }
        
        pkey->listFetch_state = libssh2_NB_state_sent;
    }

    while (1) {
        rc = libssh2_publickey_packet_receive(pkey, &pkey->listFetch_data, &pkey->listFetch_data_len);
        if (rc == PACKET_EAGAIN) {
            return PACKET_EAGAIN;
        }
        else if (rc) {
            libssh2_error(session, LIBSSH2_ERROR_SOCKET_TIMEOUT, "Timeout waiting for response from publickey subsystem", 0);
            goto err_exit;
        }

        pkey->listFetch_s = pkey->listFetch_data;
        if ((response = libssh2_publickey_response_id(&pkey->listFetch_s, pkey->listFetch_data_len)) < 0) {
            libssh2_error(session, LIBSSH2_ERROR_PUBLICKEY_PROTOCOL, "Invalid publickey subsystem response code", 0);
            goto err_exit;
        }

        switch (response) {
            case LIBSSH2_PUBLICKEY_RESPONSE_STATUS:
            /* Error, or processing complete */
            {
                unsigned long status, descr_len, lang_len;
                unsigned char *descr, *lang;
                
                status = libssh2_ntohu32(pkey->listFetch_s);                    pkey->listFetch_s += 4;
                descr_len = libssh2_ntohu32(pkey->listFetch_s);                 pkey->listFetch_s += 4;
                descr = pkey->listFetch_s;                                      pkey->listFetch_s += descr_len;
                lang_len = libssh2_ntohu32(pkey->listFetch_s);                  pkey->listFetch_s += 4;
                lang = pkey->listFetch_s;                                       pkey->listFetch_s += lang_len;

                if (pkey->listFetch_s > pkey->listFetch_data + pkey->listFetch_data_len) {
                    libssh2_error(session, LIBSSH2_ERROR_PUBLICKEY_PROTOCOL, "Malformed publickey subsystem packet", 0);
                    goto err_exit;
                }

                if (status == LIBSSH2_PUBLICKEY_SUCCESS) {
                    LIBSSH2_FREE(session, pkey->listFetch_data);
                    pkey->listFetch_data = NULL;
                    *pkey_list = list;
                    *num_keys = keys;
                    pkey->listFetch_state = libssh2_NB_state_idle;
                    return 0;
                }

                libssh2_publickey_status_error(pkey, session, status, descr, descr_len);
                goto err_exit;
            }
            case LIBSSH2_PUBLICKEY_RESPONSE_PUBLICKEY:
                /* What we want */
                if (keys >= max_keys) {
                    libssh2_publickey_list *newlist;
                    /* Grow the key list if necessary */
                    max_keys += 8;
                    newlist = LIBSSH2_REALLOC(session, list, (max_keys + 1) * sizeof(libssh2_publickey_list));
                    if (!newlist) {
                        libssh2_error(session, LIBSSH2_ERROR_ALLOC, "Unable to allocate memory for publickey list", 0);
                        goto err_exit;
                    }
                    list = newlist;
                }
                if (pkey->version == 1) {
                    unsigned long comment_len;

                    comment_len = libssh2_ntohu32(pkey->listFetch_s);           pkey->listFetch_s += 4;
                    if (comment_len) {
                        list[keys].num_attrs = 1;
                        list[keys].attrs = LIBSSH2_ALLOC(session, sizeof(libssh2_publickey_attribute));
                        if (!list[keys].attrs) {
                            libssh2_error(session, LIBSSH2_ERROR_ALLOC, "Unable to allocate memory for publickey attributes", 0);
                            goto err_exit;
                        }
                        list[keys].attrs[0].name = "comment";
                        list[keys].attrs[0].name_len = sizeof("comment") - 1;
                        list[keys].attrs[0].value = (char *)pkey->listFetch_s;
                        list[keys].attrs[0].value_len = comment_len;
                        list[keys].attrs[0].mandatory = 0;

                        pkey->listFetch_s += comment_len;
                    } else {
                        list[keys].num_attrs = 0;
                        list[keys].attrs = NULL;
                    }
                    list[keys].name_len = libssh2_ntohu32(pkey->listFetch_s);   pkey->listFetch_s += 4;
                    list[keys].name = pkey->listFetch_s;                        pkey->listFetch_s += list[keys].name_len;
                    list[keys].blob_len = libssh2_ntohu32(pkey->listFetch_s);   pkey->listFetch_s += 4;
                    list[keys].blob = pkey->listFetch_s;                        pkey->listFetch_s += list[keys].blob_len;
                } else {
                    /* Version == 2 */
                    list[keys].name_len = libssh2_ntohu32(pkey->listFetch_s);   pkey->listFetch_s += 4;
                    list[keys].name = pkey->listFetch_s;                        pkey->listFetch_s += list[keys].name_len;
                    list[keys].blob_len = libssh2_ntohu32(pkey->listFetch_s);   pkey->listFetch_s += 4;
                    list[keys].blob = pkey->listFetch_s;                        pkey->listFetch_s += list[keys].blob_len;
                    list[keys].num_attrs = libssh2_ntohu32(pkey->listFetch_s);  pkey->listFetch_s += 4;
                    if (list[keys].num_attrs) {
                        list[keys].attrs = LIBSSH2_ALLOC(session, list[keys].num_attrs * sizeof(libssh2_publickey_attribute));
                        if (!list[keys].attrs) {
                            libssh2_error(session, LIBSSH2_ERROR_ALLOC, "Unable to allocate memory for publickey attributes", 0);
                            goto err_exit;
                        }
                        for(i = 0; i < list[keys].num_attrs; i++) {
                            list[keys].attrs[i].name_len = libssh2_ntohu32(pkey->listFetch_s);
                                                                                pkey->listFetch_s += 4;
                            list[keys].attrs[i].name = (char *)pkey->listFetch_s;
                                                                                pkey->listFetch_s += list[keys].attrs[i].name_len;
                            list[keys].attrs[i].value_len = libssh2_ntohu32(pkey->listFetch_s);
                                                                                pkey->listFetch_s += 4;
                            list[keys].attrs[i].value = (char *)pkey->listFetch_s;
                                                                                pkey->listFetch_s += list[keys].attrs[i].value_len;
                            list[keys].attrs[i].mandatory = 0;  /* actually an ignored value */
                        }
                    } else {
                        list[keys].attrs = NULL;
                    }
                }
                list[keys].packet = pkey->listFetch_data; /* To be FREEd in libssh2_publickey_list_free() */
                keys++;

                list[keys].packet = NULL; /* Terminate the list */
                pkey->listFetch_data = NULL;
                break;
            default:
                /* Unknown/Unexpected */
                libssh2_error(session, LIBSSH2_ERROR_PUBLICKEY_PROTOCOL, "Unexpected publickey subsystem response, ignoring", 0);
                LIBSSH2_FREE(session, pkey->listFetch_data);
                pkey->listFetch_data = NULL;
        }
    }

    /* Only reached via explicit goto */
 err_exit:
    if (pkey->listFetch_data) {
        LIBSSH2_FREE(session, pkey->listFetch_data);
        pkey->listFetch_data = NULL;
    }
    if (list) {
        libssh2_publickey_list_free(pkey, list);
    }
    pkey->listFetch_state = libssh2_NB_state_idle;
    return -1;
}
/* }}} */

/* {{{ libssh2_publickey_list_free
 * Free a previously fetched list of public keys
 */
LIBSSH2_API void libssh2_publickey_list_free(LIBSSH2_PUBLICKEY *pkey, libssh2_publickey_list *pkey_list)
{
    LIBSSH2_SESSION *session = pkey->channel->session;
    libssh2_publickey_list *p = pkey_list;

    while (p->packet) {
        if (p->attrs) {
            LIBSSH2_FREE(session, p->attrs);
        }
        LIBSSH2_FREE(session, p->packet);
        p++;
    }

    LIBSSH2_FREE(session, pkey_list);
}
/* }}} */

/* {{{ libssh2_publickey_shutdown
 * Shutdown the publickey subsystem
 */
LIBSSH2_API int libssh2_publickey_shutdown(LIBSSH2_PUBLICKEY *pkey)
{
    LIBSSH2_SESSION *session = pkey->channel->session;

    /*
     * Make sure all memory used in the state variables are free
     */
    if (pkey->receive_packet) {
        LIBSSH2_FREE(session, pkey->receive_packet);
        pkey->receive_packet = NULL;
    }
    if (pkey->add_packet) {
        LIBSSH2_FREE(session, pkey->add_packet);
        pkey->add_packet = NULL;
    }
    if (pkey->remove_packet) {
        LIBSSH2_FREE(session, pkey->remove_packet);
        pkey->remove_packet = NULL;
    }
    if (pkey->listFetch_data) {
        LIBSSH2_FREE(session, pkey->listFetch_data);
        pkey->listFetch_data = NULL;
    }
    
    if (libssh2_channel_free(pkey->channel) == PACKET_EAGAIN) {
        return PACKET_EAGAIN;
    }
    
    LIBSSH2_FREE(session, pkey);
    return 0;
}
/* }}} */