fe-auth.c

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/*-------------------------------------------------------------------------
 *
 * fe-auth.c
 *     The front-end (client) authorization routines
 *
 * Portions Copyright (c) 1996-2013, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * IDENTIFICATION
 *    src/interfaces/libpq/fe-auth.c
 *
 *-------------------------------------------------------------------------
 */

/*
 * INTERFACE ROUTINES
 *     frontend (client) routines:
 *      pg_fe_sendauth          send authentication information
 *      pg_fe_getauthname       get user's name according to the client side
 *                              of the authentication system
 */

#include "postgres_fe.h"

#ifdef WIN32
#include "win32.h"
#else
#include <unistd.h>
#include <fcntl.h>
#include <sys/param.h>          /* for MAXHOSTNAMELEN on most */
#include <sys/socket.h>
#ifdef HAVE_SYS_UCRED_H
#include <sys/ucred.h>
#endif
#ifndef  MAXHOSTNAMELEN
#include <netdb.h>              /* for MAXHOSTNAMELEN on some */
#endif
#include <pwd.h>
#endif

#include "libpq-fe.h"
#include "fe-auth.h"
#include "libpq/md5.h"


#ifdef KRB5
/*
 * MIT Kerberos authentication system - protocol version 5
 */

#include <krb5.h>
/* Some old versions of Kerberos do not include <com_err.h> in <krb5.h> */
#if !defined(__COM_ERR_H) && !defined(__COM_ERR_H__)
#include <com_err.h>
#endif

/*
 * Heimdal doesn't have a free function for unparsed names. Just pass it to
 * standard free() which should work in these cases.
 */
#ifndef HAVE_KRB5_FREE_UNPARSED_NAME
static void
krb5_free_unparsed_name(krb5_context context, char *val)
{
    free(val);
}
#endif

/*
 * pg_an_to_ln -- return the local name corresponding to an authentication
 *                name
 *
 * XXX Assumes that the first aname component is the user name.  This is NOT
 *     necessarily so, since an aname can actually be something out of your
 *     worst X.400 nightmare, like
 *        ORGANIZATION=U. C. Berkeley/NAME=Paul M. [email protected]
 *     Note that the MIT an_to_ln code does the same thing if you don't
 *     provide an aname mapping database...it may be a better idea to use
 *     krb5_an_to_ln, except that it punts if multiple components are found,
 *     and we can't afford to punt.
 *
 * For WIN32, convert username to lowercase because the Win32 kerberos library
 * generates tickets with the username as the user entered it instead of as
 * it is entered in the directory.
 */
static char *
pg_an_to_ln(char *aname)
{
    char       *p;

    if ((p = strchr(aname, '/')) || (p = strchr(aname, '@')))
        *p = '\0';
#ifdef WIN32
    for (p = aname; *p; p++)
        *p = pg_tolower((unsigned char) *p);
#endif

    return aname;
}


/*
 * Various krb5 state which is not connection specific, and a flag to
 * indicate whether we have initialised it yet.
 */
/*
static int  pg_krb5_initialised;
static krb5_context pg_krb5_context;
static krb5_ccache pg_krb5_ccache;
static krb5_principal pg_krb5_client;
static char *pg_krb5_name;
*/

struct krb5_info
{
    int         pg_krb5_initialised;
    krb5_context pg_krb5_context;
    krb5_ccache pg_krb5_ccache;
    krb5_principal pg_krb5_client;
    char       *pg_krb5_name;
};


static int
pg_krb5_init(PQExpBuffer errorMessage, struct krb5_info * info)
{
    krb5_error_code retval;

    if (info->pg_krb5_initialised)
        return STATUS_OK;

    retval = krb5_init_context(&(info->pg_krb5_context));
    if (retval)
    {
        printfPQExpBuffer(errorMessage,
                          "pg_krb5_init: krb5_init_context: %s\n",
                          error_message(retval));
        return STATUS_ERROR;
    }

    retval = krb5_cc_default(info->pg_krb5_context, &(info->pg_krb5_ccache));
    if (retval)
    {
        printfPQExpBuffer(errorMessage,
                          "pg_krb5_init: krb5_cc_default: %s\n",
                          error_message(retval));
        krb5_free_context(info->pg_krb5_context);
        return STATUS_ERROR;
    }

    retval = krb5_cc_get_principal(info->pg_krb5_context, info->pg_krb5_ccache,
                                   &(info->pg_krb5_client));
    if (retval)
    {
        printfPQExpBuffer(errorMessage,
                          "pg_krb5_init: krb5_cc_get_principal: %s\n",
                          error_message(retval));
        krb5_cc_close(info->pg_krb5_context, info->pg_krb5_ccache);
        krb5_free_context(info->pg_krb5_context);
        return STATUS_ERROR;
    }

    retval = krb5_unparse_name(info->pg_krb5_context, info->pg_krb5_client, &(info->pg_krb5_name));
    if (retval)
    {
        printfPQExpBuffer(errorMessage,
                          "pg_krb5_init: krb5_unparse_name: %s\n",
                          error_message(retval));
        krb5_free_principal(info->pg_krb5_context, info->pg_krb5_client);
        krb5_cc_close(info->pg_krb5_context, info->pg_krb5_ccache);
        krb5_free_context(info->pg_krb5_context);
        return STATUS_ERROR;
    }

    info->pg_krb5_name = pg_an_to_ln(info->pg_krb5_name);

    info->pg_krb5_initialised = 1;
    return STATUS_OK;
}

static void
pg_krb5_destroy(struct krb5_info * info)
{
    krb5_free_principal(info->pg_krb5_context, info->pg_krb5_client);
    krb5_cc_close(info->pg_krb5_context, info->pg_krb5_ccache);
    krb5_free_unparsed_name(info->pg_krb5_context, info->pg_krb5_name);
    krb5_free_context(info->pg_krb5_context);
}


/*
 * pg_krb5_sendauth -- client routine to send authentication information to
 *                     the server
 */
static int
pg_krb5_sendauth(PGconn *conn)
{
    krb5_error_code retval;
    int         ret;
    krb5_principal server;
    krb5_auth_context auth_context = NULL;
    krb5_error *err_ret = NULL;
    struct krb5_info info;

    info.pg_krb5_initialised = 0;

    if (!(conn->pghost && conn->pghost[0] != '\0'))
    {
        printfPQExpBuffer(&conn->errorMessage,
                          libpq_gettext("host name must be specified\n"));
        return STATUS_ERROR;
    }

    ret = pg_krb5_init(&conn->errorMessage, &info);
    if (ret != STATUS_OK)
        return ret;

    retval = krb5_sname_to_principal(info.pg_krb5_context, conn->pghost,
                                     conn->krbsrvname,
                                     KRB5_NT_SRV_HST, &server);
    if (retval)
    {
        printfPQExpBuffer(&conn->errorMessage,
                          "pg_krb5_sendauth: krb5_sname_to_principal: %s\n",
                          error_message(retval));
        pg_krb5_destroy(&info);
        return STATUS_ERROR;
    }

    /*
     * libpq uses a non-blocking socket. But kerberos needs a blocking socket,
     * and we have to block somehow to do mutual authentication anyway. So we
     * temporarily make it blocking.
     */
    if (!pg_set_block(conn->sock))
    {
        char        sebuf[256];

        printfPQExpBuffer(&conn->errorMessage,
                          libpq_gettext("could not set socket to blocking mode: %s\n"), pqStrerror(errno, sebuf, sizeof(sebuf)));
        krb5_free_principal(info.pg_krb5_context, server);
        pg_krb5_destroy(&info);
        return STATUS_ERROR;
    }

    retval = krb5_sendauth(info.pg_krb5_context, &auth_context,
                       (krb5_pointer) &conn->sock, (char *) conn->krbsrvname,
                           info.pg_krb5_client, server,
                           AP_OPTS_MUTUAL_REQUIRED,
                           NULL, 0,     /* no creds, use ccache instead */
                           info.pg_krb5_ccache, &err_ret, NULL, NULL);
    if (retval)
    {
        if (retval == KRB5_SENDAUTH_REJECTED && err_ret)
        {
#if defined(HAVE_KRB5_ERROR_TEXT_DATA)
            printfPQExpBuffer(&conn->errorMessage,
                  libpq_gettext("Kerberos 5 authentication rejected: %*s\n"),
                              (int) err_ret->text.length, err_ret->text.data);
#elif defined(HAVE_KRB5_ERROR_E_DATA)
            printfPQExpBuffer(&conn->errorMessage,
                  libpq_gettext("Kerberos 5 authentication rejected: %*s\n"),
                              (int) err_ret->e_data->length,
                              (const char *) err_ret->e_data->data);
#else
#error "bogus configuration"
#endif
        }
        else
        {
            printfPQExpBuffer(&conn->errorMessage,
                              "krb5_sendauth: %s\n", error_message(retval));
        }

        if (err_ret)
            krb5_free_error(info.pg_krb5_context, err_ret);

        ret = STATUS_ERROR;
    }

    krb5_free_principal(info.pg_krb5_context, server);

    if (!pg_set_noblock(conn->sock))
    {
        char        sebuf[256];

        printfPQExpBuffer(&conn->errorMessage,
        libpq_gettext("could not restore nonblocking mode on socket: %s\n"),
                          pqStrerror(errno, sebuf, sizeof(sebuf)));
        ret = STATUS_ERROR;
    }
    pg_krb5_destroy(&info);

    return ret;
}
#endif   /* KRB5 */

#ifdef ENABLE_GSS
/*
 * GSSAPI authentication system.
 */

#if defined(WIN32) && !defined(WIN32_ONLY_COMPILER)
/*
 * MIT Kerberos GSSAPI DLL doesn't properly export the symbols for MingW
 * that contain the OIDs required. Redefine here, values copied
 * from src/athena/auth/krb5/src/lib/gssapi/generic/gssapi_generic.c
 */
static const gss_OID_desc GSS_C_NT_HOSTBASED_SERVICE_desc =
{10, (void *) "\x2a\x86\x48\x86\xf7\x12\x01\x02\x01\x04"};
static GSS_DLLIMP gss_OID GSS_C_NT_HOSTBASED_SERVICE = &GSS_C_NT_HOSTBASED_SERVICE_desc;
#endif

/*
 * Fetch all errors of a specific type and append to "str".
 */
static void
pg_GSS_error_int(PQExpBuffer str, const char *mprefix,
                 OM_uint32 stat, int type)
{
    OM_uint32   lmin_s;
    gss_buffer_desc lmsg;
    OM_uint32   msg_ctx = 0;

    do
    {
        gss_display_status(&lmin_s, stat, type,
                           GSS_C_NO_OID, &msg_ctx, &lmsg);
        appendPQExpBuffer(str, "%s: %s\n", mprefix, (char *) lmsg.value);
        gss_release_buffer(&lmin_s, &lmsg);
    } while (msg_ctx);
}

/*
 * GSSAPI errors contain two parts; put both into conn->errorMessage.
 */
static void
pg_GSS_error(const char *mprefix, PGconn *conn,
             OM_uint32 maj_stat, OM_uint32 min_stat)
{
    resetPQExpBuffer(&conn->errorMessage);

    /* Fetch major error codes */
    pg_GSS_error_int(&conn->errorMessage, mprefix, maj_stat, GSS_C_GSS_CODE);

    /* Add the minor codes as well */
    pg_GSS_error_int(&conn->errorMessage, mprefix, min_stat, GSS_C_MECH_CODE);
}

/*
 * Continue GSS authentication with next token as needed.
 */
static int
pg_GSS_continue(PGconn *conn)
{
    OM_uint32   maj_stat,
                min_stat,
                lmin_s;

    maj_stat = gss_init_sec_context(&min_stat,
                                    GSS_C_NO_CREDENTIAL,
                                    &conn->gctx,
                                    conn->gtarg_nam,
                                    GSS_C_NO_OID,
                                    GSS_C_MUTUAL_FLAG,
                                    0,
                                    GSS_C_NO_CHANNEL_BINDINGS,
          (conn->gctx == GSS_C_NO_CONTEXT) ? GSS_C_NO_BUFFER : &conn->ginbuf,
                                    NULL,
                                    &conn->goutbuf,
                                    NULL,
                                    NULL);

    if (conn->gctx != GSS_C_NO_CONTEXT)
    {
        free(conn->ginbuf.value);
        conn->ginbuf.value = NULL;
        conn->ginbuf.length = 0;
    }

    if (conn->goutbuf.length != 0)
    {
        /*
         * GSS generated data to send to the server. We don't care if it's the
         * first or subsequent packet, just send the same kind of password
         * packet.
         */
        if (pqPacketSend(conn, 'p',
                         conn->goutbuf.value, conn->goutbuf.length)
            != STATUS_OK)
        {
            gss_release_buffer(&lmin_s, &conn->goutbuf);
            return STATUS_ERROR;
        }
    }
    gss_release_buffer(&lmin_s, &conn->goutbuf);

    if (maj_stat != GSS_S_COMPLETE && maj_stat != GSS_S_CONTINUE_NEEDED)
    {
        pg_GSS_error(libpq_gettext("GSSAPI continuation error"),
                     conn,
                     maj_stat, min_stat);
        gss_release_name(&lmin_s, &conn->gtarg_nam);
        if (conn->gctx)
            gss_delete_sec_context(&lmin_s, &conn->gctx, GSS_C_NO_BUFFER);
        return STATUS_ERROR;
    }

    if (maj_stat == GSS_S_COMPLETE)
        gss_release_name(&lmin_s, &conn->gtarg_nam);

    return STATUS_OK;
}

/*
 * Send initial GSS authentication token
 */
static int
pg_GSS_startup(PGconn *conn)
{
    OM_uint32   maj_stat,
                min_stat;
    int         maxlen;
    gss_buffer_desc temp_gbuf;

    if (!(conn->pghost && conn->pghost[0] != '\0'))
    {
        printfPQExpBuffer(&conn->errorMessage,
                          libpq_gettext("host name must be specified\n"));
        return STATUS_ERROR;
    }

    if (conn->gctx)
    {
        printfPQExpBuffer(&conn->errorMessage,
                    libpq_gettext("duplicate GSS authentication request\n"));
        return STATUS_ERROR;
    }

    /*
     * Import service principal name so the proper ticket can be acquired by
     * the GSSAPI system.
     */
    maxlen = NI_MAXHOST + strlen(conn->krbsrvname) + 2;
    temp_gbuf.value = (char *) malloc(maxlen);
    snprintf(temp_gbuf.value, maxlen, "%s@%s",
             conn->krbsrvname, conn->pghost);
    temp_gbuf.length = strlen(temp_gbuf.value);

    maj_stat = gss_import_name(&min_stat, &temp_gbuf,
                               GSS_C_NT_HOSTBASED_SERVICE, &conn->gtarg_nam);
    free(temp_gbuf.value);

    if (maj_stat != GSS_S_COMPLETE)
    {
        pg_GSS_error(libpq_gettext("GSSAPI name import error"),
                     conn,
                     maj_stat, min_stat);
        return STATUS_ERROR;
    }

    /*
     * Initial packet is the same as a continuation packet with no initial
     * context.
     */
    conn->gctx = GSS_C_NO_CONTEXT;

    return pg_GSS_continue(conn);
}
#endif   /* ENABLE_GSS */


#ifdef ENABLE_SSPI
/*
 * SSPI authentication system (Windows only)
 */

static void
pg_SSPI_error(PGconn *conn, const char *mprefix, SECURITY_STATUS r)
{
    char        sysmsg[256];

    if (FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM, NULL, r, 0,
                      sysmsg, sizeof(sysmsg), NULL) == 0)
        printfPQExpBuffer(&conn->errorMessage, "%s: SSPI error %x",
                          mprefix, (unsigned int) r);
    else
        printfPQExpBuffer(&conn->errorMessage, "%s: %s (%x)",
                          mprefix, sysmsg, (unsigned int) r);
}

/*
 * Continue SSPI authentication with next token as needed.
 */
static int
pg_SSPI_continue(PGconn *conn)
{
    SECURITY_STATUS r;
    CtxtHandle  newContext;
    ULONG       contextAttr;
    SecBufferDesc inbuf;
    SecBufferDesc outbuf;
    SecBuffer   OutBuffers[1];
    SecBuffer   InBuffers[1];

    if (conn->sspictx != NULL)
    {
        /*
         * On runs other than the first we have some data to send. Put this
         * data in a SecBuffer type structure.
         */
        inbuf.ulVersion = SECBUFFER_VERSION;
        inbuf.cBuffers = 1;
        inbuf.pBuffers = InBuffers;
        InBuffers[0].pvBuffer = conn->ginbuf.value;
        InBuffers[0].cbBuffer = conn->ginbuf.length;
        InBuffers[0].BufferType = SECBUFFER_TOKEN;
    }

    OutBuffers[0].pvBuffer = NULL;
    OutBuffers[0].BufferType = SECBUFFER_TOKEN;
    OutBuffers[0].cbBuffer = 0;
    outbuf.cBuffers = 1;
    outbuf.pBuffers = OutBuffers;
    outbuf.ulVersion = SECBUFFER_VERSION;

    r = InitializeSecurityContext(conn->sspicred,
                                  conn->sspictx,
                                  conn->sspitarget,
                                  ISC_REQ_ALLOCATE_MEMORY,
                                  0,
                                  SECURITY_NETWORK_DREP,
                                  (conn->sspictx == NULL) ? NULL : &inbuf,
                                  0,
                                  &newContext,
                                  &outbuf,
                                  &contextAttr,
                                  NULL);

    if (r != SEC_E_OK && r != SEC_I_CONTINUE_NEEDED)
    {
        pg_SSPI_error(conn, libpq_gettext("SSPI continuation error"), r);

        return STATUS_ERROR;
    }

    if (conn->sspictx == NULL)
    {
        /* On first run, transfer retreived context handle */
        conn->sspictx = malloc(sizeof(CtxtHandle));
        if (conn->sspictx == NULL)
        {
            printfPQExpBuffer(&conn->errorMessage, libpq_gettext("out of memory\n"));
            return STATUS_ERROR;
        }
        memcpy(conn->sspictx, &newContext, sizeof(CtxtHandle));
    }
    else
    {
        /*
         * On subsequent runs when we had data to send, free buffers that
         * contained this data.
         */
        free(conn->ginbuf.value);
        conn->ginbuf.value = NULL;
        conn->ginbuf.length = 0;
    }

    /*
     * If SSPI returned any data to be sent to the server (as it normally
     * would), send this data as a password packet.
     */
    if (outbuf.cBuffers > 0)
    {
        if (outbuf.cBuffers != 1)
        {
            /*
             * This should never happen, at least not for Kerberos
             * authentication. Keep check in case it shows up with other
             * authentication methods later.
             */
            printfPQExpBuffer(&conn->errorMessage, "SSPI returned invalid number of output buffers\n");
            return STATUS_ERROR;
        }

        /*
         * If the negotiation is complete, there may be zero bytes to send.
         * The server is at this point not expecting any more data, so don't
         * send it.
         */
        if (outbuf.pBuffers[0].cbBuffer > 0)
        {
            if (pqPacketSend(conn, 'p',
                   outbuf.pBuffers[0].pvBuffer, outbuf.pBuffers[0].cbBuffer))
            {
                FreeContextBuffer(outbuf.pBuffers[0].pvBuffer);
                return STATUS_ERROR;
            }
        }
        FreeContextBuffer(outbuf.pBuffers[0].pvBuffer);
    }

    /* Cleanup is handled by the code in freePGconn() */
    return STATUS_OK;
}

/*
 * Send initial SSPI authentication token.
 * If use_negotiate is 0, use kerberos authentication package which is
 * compatible with Unix. If use_negotiate is 1, use the negotiate package
 * which supports both kerberos and NTLM, but is not compatible with Unix.
 */
static int
pg_SSPI_startup(PGconn *conn, int use_negotiate)
{
    SECURITY_STATUS r;
    TimeStamp   expire;

    conn->sspictx = NULL;

    /*
     * Retreive credentials handle
     */
    conn->sspicred = malloc(sizeof(CredHandle));
    if (conn->sspicred == NULL)
    {
        printfPQExpBuffer(&conn->errorMessage, libpq_gettext("out of memory\n"));
        return STATUS_ERROR;
    }

    r = AcquireCredentialsHandle(NULL,
                                 use_negotiate ? "negotiate" : "kerberos",
                                 SECPKG_CRED_OUTBOUND,
                                 NULL,
                                 NULL,
                                 NULL,
                                 NULL,
                                 conn->sspicred,
                                 &expire);
    if (r != SEC_E_OK)
    {
        pg_SSPI_error(conn, libpq_gettext("could not acquire SSPI credentials"), r);
        free(conn->sspicred);
        conn->sspicred = NULL;
        return STATUS_ERROR;
    }

    /*
     * Compute target principal name. SSPI has a different format from GSSAPI,
     * but not more complex. We can skip the @REALM part, because Windows will
     * fill that in for us automatically.
     */
    if (!(conn->pghost && conn->pghost[0] != '\0'))
    {
        printfPQExpBuffer(&conn->errorMessage,
                          libpq_gettext("host name must be specified\n"));
        return STATUS_ERROR;
    }
    conn->sspitarget = malloc(strlen(conn->krbsrvname) + strlen(conn->pghost) + 2);
    if (!conn->sspitarget)
    {
        printfPQExpBuffer(&conn->errorMessage, libpq_gettext("out of memory\n"));
        return STATUS_ERROR;
    }
    sprintf(conn->sspitarget, "%s/%s", conn->krbsrvname, conn->pghost);

    /*
     * Indicate that we're in SSPI authentication mode to make sure that
     * pg_SSPI_continue is called next time in the negotiation.
     */
    conn->usesspi = 1;

    return pg_SSPI_continue(conn);
}
#endif   /* ENABLE_SSPI */

/*
 * Respond to AUTH_REQ_SCM_CREDS challenge.
 *
 * Note: this is dead code as of Postgres 9.1, because current backends will
 * never send this challenge.  But we must keep it as long as libpq needs to
 * interoperate with pre-9.1 servers.  It is believed to be needed only on
 * Debian/kFreeBSD (ie, FreeBSD kernel with Linux userland, so that the
 * getpeereid() function isn't provided by libc).
 */
static int
pg_local_sendauth(PGconn *conn)
{
#ifdef HAVE_STRUCT_CMSGCRED
    char        buf;
    struct iovec iov;
    struct msghdr msg;
    struct cmsghdr *cmsg;
    union
    {
        struct cmsghdr hdr;
        unsigned char buf[CMSG_SPACE(sizeof(struct cmsgcred))];
    }           cmsgbuf;

    /*
     * The backend doesn't care what we send here, but it wants exactly one
     * character to force recvmsg() to block and wait for us.
     */
    buf = '\0';
    iov.iov_base = &buf;
    iov.iov_len = 1;

    memset(&msg, 0, sizeof(msg));
    msg.msg_iov = &iov;
    msg.msg_iovlen = 1;

    /* We must set up a message that will be filled in by kernel */
    memset(&cmsgbuf, 0, sizeof(cmsgbuf));
    msg.msg_control = &cmsgbuf.buf;
    msg.msg_controllen = sizeof(cmsgbuf.buf);
    cmsg = CMSG_FIRSTHDR(&msg);
    cmsg->cmsg_len = CMSG_LEN(sizeof(struct cmsgcred));
    cmsg->cmsg_level = SOL_SOCKET;
    cmsg->cmsg_type = SCM_CREDS;

    if (sendmsg(conn->sock, &msg, 0) == -1)
    {
        char        sebuf[256];

        printfPQExpBuffer(&conn->errorMessage,
                          "pg_local_sendauth: sendmsg: %s\n",
                          pqStrerror(errno, sebuf, sizeof(sebuf)));
        return STATUS_ERROR;
    }
    return STATUS_OK;
#else
    printfPQExpBuffer(&conn->errorMessage,
            libpq_gettext("SCM_CRED authentication method not supported\n"));
    return STATUS_ERROR;
#endif
}

static int
pg_password_sendauth(PGconn *conn, const char *password, AuthRequest areq)
{
    int         ret;
    char       *crypt_pwd = NULL;
    const char *pwd_to_send;

    /* Encrypt the password if needed. */

    switch (areq)
    {
        case AUTH_REQ_MD5:
            {
                char       *crypt_pwd2;

                /* Allocate enough space for two MD5 hashes */
                crypt_pwd = malloc(2 * (MD5_PASSWD_LEN + 1));
                if (!crypt_pwd)
                {
                    printfPQExpBuffer(&conn->errorMessage,
                                      libpq_gettext("out of memory\n"));
                    return STATUS_ERROR;
                }

                crypt_pwd2 = crypt_pwd + MD5_PASSWD_LEN + 1;
                if (!pg_md5_encrypt(password, conn->pguser,
                                    strlen(conn->pguser), crypt_pwd2))
                {
                    free(crypt_pwd);
                    return STATUS_ERROR;
                }
                if (!pg_md5_encrypt(crypt_pwd2 + strlen("md5"), conn->md5Salt,
                                    sizeof(conn->md5Salt), crypt_pwd))
                {
                    free(crypt_pwd);
                    return STATUS_ERROR;
                }

                pwd_to_send = crypt_pwd;
                break;
            }
        case AUTH_REQ_PASSWORD:
            pwd_to_send = password;
            break;
        default:
            return STATUS_ERROR;
    }
    /* Packet has a message type as of protocol 3.0 */
    if (PG_PROTOCOL_MAJOR(conn->pversion) >= 3)
        ret = pqPacketSend(conn, 'p', pwd_to_send, strlen(pwd_to_send) + 1);
    else
        ret = pqPacketSend(conn, 0, pwd_to_send, strlen(pwd_to_send) + 1);
    if (crypt_pwd)
        free(crypt_pwd);
    return ret;
}

/*
 * pg_fe_sendauth
 *      client demux routine for outgoing authentication information
 */
int
pg_fe_sendauth(AuthRequest areq, PGconn *conn)
{
    switch (areq)
    {
        case AUTH_REQ_OK:
            break;

        case AUTH_REQ_KRB4:
            printfPQExpBuffer(&conn->errorMessage,
                 libpq_gettext("Kerberos 4 authentication not supported\n"));
            return STATUS_ERROR;

        case AUTH_REQ_KRB5:
#ifdef KRB5
            pglock_thread();
            if (pg_krb5_sendauth(conn) != STATUS_OK)
            {
                /* Error message already filled in */
                pgunlock_thread();
                return STATUS_ERROR;
            }
            pgunlock_thread();
            break;
#else
            printfPQExpBuffer(&conn->errorMessage,
                 libpq_gettext("Kerberos 5 authentication not supported\n"));
            return STATUS_ERROR;
#endif

#if defined(ENABLE_GSS) || defined(ENABLE_SSPI)
        case AUTH_REQ_GSS:
#if !defined(ENABLE_SSPI)
            /* no native SSPI, so use GSSAPI library for it */
        case AUTH_REQ_SSPI:
#endif
            {
                int         r;

                pglock_thread();

                /*
                 * If we have both GSS and SSPI support compiled in, use SSPI
                 * support by default. This is overridable by a connection
                 * string parameter. Note that when using SSPI we still leave
                 * the negotiate parameter off, since we want SSPI to use the
                 * GSSAPI kerberos protocol. For actual SSPI negotiate
                 * protocol, we use AUTH_REQ_SSPI.
                 */
#if defined(ENABLE_GSS) && defined(ENABLE_SSPI)
                if (conn->gsslib && (pg_strcasecmp(conn->gsslib, "gssapi") == 0))
                    r = pg_GSS_startup(conn);
                else
                    r = pg_SSPI_startup(conn, 0);
#elif defined(ENABLE_GSS) && !defined(ENABLE_SSPI)
                r = pg_GSS_startup(conn);
#elif !defined(ENABLE_GSS) && defined(ENABLE_SSPI)
                r = pg_SSPI_startup(conn, 0);
#endif
                if (r != STATUS_OK)
                {
                    /* Error message already filled in. */
                    pgunlock_thread();
                    return STATUS_ERROR;
                }
                pgunlock_thread();
            }
            break;

        case AUTH_REQ_GSS_CONT:
            {
                int         r;

                pglock_thread();
#if defined(ENABLE_GSS) && defined(ENABLE_SSPI)
                if (conn->usesspi)
                    r = pg_SSPI_continue(conn);
                else
                    r = pg_GSS_continue(conn);
#elif defined(ENABLE_GSS) && !defined(ENABLE_SSPI)
                r = pg_GSS_continue(conn);
#elif !defined(ENABLE_GSS) && defined(ENABLE_SSPI)
                r = pg_SSPI_continue(conn);
#endif
                if (r != STATUS_OK)
                {
                    /* Error message already filled in. */
                    pgunlock_thread();
                    return STATUS_ERROR;
                }
                pgunlock_thread();
            }
            break;
#else                           /* defined(ENABLE_GSS) || defined(ENABLE_SSPI) */
            /* No GSSAPI *or* SSPI support */
        case AUTH_REQ_GSS:
        case AUTH_REQ_GSS_CONT:
            printfPQExpBuffer(&conn->errorMessage,
                     libpq_gettext("GSSAPI authentication not supported\n"));
            return STATUS_ERROR;
#endif   /* defined(ENABLE_GSS) || defined(ENABLE_SSPI) */

#ifdef ENABLE_SSPI
        case AUTH_REQ_SSPI:

            /*
             * SSPI has it's own startup message so libpq can decide which
             * method to use. Indicate to pg_SSPI_startup that we want SSPI
             * negotiation instead of Kerberos.
             */
            pglock_thread();
            if (pg_SSPI_startup(conn, 1) != STATUS_OK)
            {
                /* Error message already filled in. */
                pgunlock_thread();
                return STATUS_ERROR;
            }
            pgunlock_thread();
            break;
#else

            /*
             * No SSPI support. However, if we have GSSAPI but not SSPI
             * support, AUTH_REQ_SSPI will have been handled in the codepath
             * for AUTH_REQ_GSSAPI above, so don't duplicate the case label in
             * that case.
             */
#if !defined(ENABLE_GSS)
        case AUTH_REQ_SSPI:
            printfPQExpBuffer(&conn->errorMessage,
                       libpq_gettext("SSPI authentication not supported\n"));
            return STATUS_ERROR;
#endif   /* !define(ENABLE_GSSAPI) */
#endif   /* ENABLE_SSPI */


        case AUTH_REQ_CRYPT:
            printfPQExpBuffer(&conn->errorMessage,
                      libpq_gettext("Crypt authentication not supported\n"));
            return STATUS_ERROR;

        case AUTH_REQ_MD5:
        case AUTH_REQ_PASSWORD:
            conn->password_needed = true;
            if (conn->pgpass == NULL || conn->pgpass[0] == '\0')
            {
                printfPQExpBuffer(&conn->errorMessage,
                                  PQnoPasswordSupplied);
                return STATUS_ERROR;
            }
            if (pg_password_sendauth(conn, conn->pgpass, areq) != STATUS_OK)
            {
                printfPQExpBuffer(&conn->errorMessage,
                     "fe_sendauth: error sending password authentication\n");
                return STATUS_ERROR;
            }
            break;

        case AUTH_REQ_SCM_CREDS:
            if (pg_local_sendauth(conn) != STATUS_OK)
                return STATUS_ERROR;
            break;

        default:
            printfPQExpBuffer(&conn->errorMessage,
            libpq_gettext("authentication method %u not supported\n"), areq);
            return STATUS_ERROR;
    }

    return STATUS_OK;
}


/*
 * pg_fe_getauthname -- returns a pointer to dynamic space containing whatever
 *                   name the user has authenticated to the system
 *
 * if there is an error, return NULL with an error message in errorMessage
 */
char *
pg_fe_getauthname(PQExpBuffer errorMessage)
{
    const char *name = NULL;
    char       *authn;

#ifdef WIN32
    char        username[128];
    DWORD       namesize = sizeof(username) - 1;
#else
    char        pwdbuf[BUFSIZ];
    struct passwd pwdstr;
    struct passwd *pw = NULL;
#endif

    /*
     * Some users are using configure --enable-thread-safety-force, so we
     * might as well do the locking within our library to protect
     * pqGetpwuid(). In fact, application developers can use getpwuid() in
     * their application if they use the locking call we provide, or install
     * their own locking function using PQregisterThreadLock().
     */
    pglock_thread();

    if (!name)
    {
#ifdef WIN32
        if (GetUserName(username, &namesize))
            name = username;
#else
        if (pqGetpwuid(geteuid(), &pwdstr, pwdbuf, sizeof(pwdbuf), &pw) == 0)
            name = pw->pw_name;
#endif
    }

    authn = name ? strdup(name) : NULL;

    pgunlock_thread();

    return authn;
}


/*
 * PQencryptPassword -- exported routine to encrypt a password
 *
 * This is intended to be used by client applications that wish to send
 * commands like ALTER USER joe PASSWORD 'pwd'.  The password need not
 * be sent in cleartext if it is encrypted on the client side.  This is
 * good because it ensures the cleartext password won't end up in logs,
 * pg_stat displays, etc.  We export the function so that clients won't
 * be dependent on low-level details like whether the enceyption is MD5
 * or something else.
 *
 * Arguments are the cleartext password, and the SQL name of the user it
 * is for.
 *
 * Return value is a malloc'd string, or NULL if out-of-memory.  The client
 * may assume the string doesn't contain any special characters that would
 * require escaping.
 */
char *
PQencryptPassword(const char *passwd, const char *user)
{
    char       *crypt_pwd;

    crypt_pwd = malloc(MD5_PASSWD_LEN + 1);
    if (!crypt_pwd)
        return NULL;

    if (!pg_md5_encrypt(passwd, user, strlen(user), crypt_pwd))
    {
        free(crypt_pwd);
        return NULL;
    }

    return crypt_pwd;
}