/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright 1998 Juniper Networks, Inc.
 * All rights reserved.
 *
 * 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/socket.h>
#include <sys/time.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#ifdef WITH_SSL
#include <openssl/hmac.h>
#include <openssl/md5.h>
#define MD5Init MD5_Init
#define MD5Update MD5_Update
#define MD5Final MD5_Final
#else
#define MD5_DIGEST_LENGTH 16
#include <md5.h>
#endif

#define MAX_FIELDS      7

/* We need the MPPE_KEY_LEN define */
#include <netgraph/ng_mppc.h>

#include <errno.h>
#include <netdb.h>
#include <stdarg.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "radlib_private.h"

static void      clear_password(struct rad_handle *);
static void      generr(struct rad_handle *, const char *, ...)
                    __printflike(2, 3);
static void      insert_scrambled_password(struct rad_handle *, int);
static void      insert_request_authenticator(struct rad_handle *, int);
static void      insert_message_authenticator(struct rad_handle *, int);
static int       is_valid_response(struct rad_handle *, int,
                    const struct sockaddr_in *);
static int       put_password_attr(struct rad_handle *, int,
                    const void *, size_t);
static int       put_raw_attr(struct rad_handle *, int,
                    const void *, size_t);
static int       split(char *, char *[], int, char *, size_t);

static void
clear_password(struct rad_handle *h)
{
        if (h->pass_len != 0) {
                explicit_bzero(h->pass, h->pass_len);
                h->pass_len = 0;
        }
        h->pass_pos = 0;
}

static void
generr(struct rad_handle *h, const char *format, ...)
{
        va_list          ap;

        va_start(ap, format);
        vsnprintf(h->errmsg, ERRSIZE, format, ap);
        va_end(ap);
}

static void
insert_scrambled_password(struct rad_handle *h, int srv)
{
        MD5_CTX ctx;
        unsigned char md5[MD5_DIGEST_LENGTH];
        const struct rad_server *srvp;
        int padded_len;
        int pos;

        srvp = &h->servers[srv];
        padded_len = h->pass_len == 0 ? 16 : (h->pass_len+15) & ~0xf;

        memcpy(md5, &h->out[POS_AUTH], LEN_AUTH);
        for (pos = 0;  pos < padded_len;  pos += 16) {
                int i;

                /* Calculate the new scrambler */
                MD5Init(&ctx);
                MD5Update(&ctx, srvp->secret, strlen(srvp->secret));
                MD5Update(&ctx, md5, 16);
                MD5Final(md5, &ctx);

                /*
                 * Mix in the current chunk of the password, and copy
                 * the result into the right place in the request.  Also
                 * modify the scrambler in place, since we will use this
                 * in calculating the scrambler for next time.
                 */
                for (i = 0;  i < 16;  i++)
                        h->out[h->pass_pos + pos + i] =
                            md5[i] ^= h->pass[pos + i];
        }
}

static void
insert_request_authenticator(struct rad_handle *h, int resp)
{
        MD5_CTX ctx;
        const struct rad_server *srvp;

        srvp = &h->servers[h->srv];

        /* Create the request authenticator */
        MD5Init(&ctx);
        MD5Update(&ctx, &h->out[POS_CODE], POS_AUTH - POS_CODE);
        if (resp)
            MD5Update(&ctx, &h->in[POS_AUTH], LEN_AUTH);
        else
            MD5Update(&ctx, &h->out[POS_AUTH], LEN_AUTH);
        MD5Update(&ctx, &h->out[POS_ATTRS], h->out_len - POS_ATTRS);
        MD5Update(&ctx, srvp->secret, strlen(srvp->secret));
        MD5Final(&h->out[POS_AUTH], &ctx);
}

static void
insert_message_authenticator(struct rad_handle *h, int resp)
{
#ifdef WITH_SSL
        u_char md[EVP_MAX_MD_SIZE];
        u_int md_len;
        const struct rad_server *srvp;
        HMAC_CTX *ctx;
        srvp = &h->servers[h->srv];

        if (h->authentic_pos != 0) {
                ctx = HMAC_CTX_new();
                HMAC_Init_ex(ctx, srvp->secret, strlen(srvp->secret), EVP_md5(), NULL);
                HMAC_Update(ctx, &h->out[POS_CODE], POS_AUTH - POS_CODE);
                if (resp)
                    HMAC_Update(ctx, &h->in[POS_AUTH], LEN_AUTH);
                else
                    HMAC_Update(ctx, &h->out[POS_AUTH], LEN_AUTH);
                HMAC_Update(ctx, &h->out[POS_ATTRS],
                    h->out_len - POS_ATTRS);
                HMAC_Final(ctx, md, &md_len);
                HMAC_CTX_free(ctx);
                memcpy(&h->out[h->authentic_pos + 2], md, md_len);
        }
#endif
}

/*
 * Return true if the current response is valid for a request to the
 * specified server.
 */
static int
is_valid_response(struct rad_handle *h, int srv,
    const struct sockaddr_in *from)
{
        MD5_CTX ctx;
        unsigned char md5[MD5_DIGEST_LENGTH];
        const struct rad_server *srvp;

        int len;
#ifdef WITH_SSL
        int alen;
        HMAC_CTX *hctx;
        u_char resp[MSGSIZE], md[EVP_MAX_MD_SIZE];
        u_int md_len;
        int pos;
#endif

        srvp = &h->servers[srv];

        /* Check the source address */
        if (from->sin_family != srvp->addr.sin_family ||
            from->sin_addr.s_addr != srvp->addr.sin_addr.s_addr ||
            from->sin_port != srvp->addr.sin_port)
                return 0;

        /* Check the message length */
        if (h->in_len < POS_ATTRS)
                return 0;
        len = (h->in[POS_LENGTH] << 8) | h->in[POS_LENGTH + 1];
        if (len < POS_ATTRS || len > h->in_len)
                return 0;

        /* Check the response authenticator */
        MD5Init(&ctx);
        MD5Update(&ctx, &h->in[POS_CODE], POS_AUTH - POS_CODE);
        MD5Update(&ctx, &h->out[POS_AUTH], LEN_AUTH);
        MD5Update(&ctx, &h->in[POS_ATTRS], len - POS_ATTRS);
        MD5Update(&ctx, srvp->secret, strlen(srvp->secret));
        MD5Final(md5, &ctx);
        if (memcmp(&h->in[POS_AUTH], md5, sizeof md5) != 0)
                return 0;

#ifdef WITH_SSL
        /*
         * For non accounting responses check the message authenticator,
         * if any.
         */
        if (h->in[POS_CODE] != RAD_ACCOUNTING_RESPONSE) {

                memcpy(resp, h->in, MSGSIZE);
                pos = POS_ATTRS;

                /* Search and verify the Message-Authenticator */
                hctx = HMAC_CTX_new();
                while (pos < len - 2) {
                        if (h->in[pos] == RAD_MESSAGE_AUTHENTIC) {
                                if (h->in[pos + 1] != MD5_DIGEST_LENGTH + 2) {
                                        HMAC_CTX_free(hctx);
                                        return 0;
                                }
                                if (len - pos < MD5_DIGEST_LENGTH + 2) {
                                        HMAC_CTX_free(hctx);
                                        return 0;
                                }

                                memset(&resp[pos + 2], 0, MD5_DIGEST_LENGTH);

                                HMAC_Init_ex(hctx, srvp->secret,
                                    strlen(srvp->secret), EVP_md5(), NULL);
                                HMAC_Update(hctx, &h->in[POS_CODE],
                                    POS_AUTH - POS_CODE);
                                HMAC_Update(hctx, &h->out[POS_AUTH],
                                    LEN_AUTH);
                                HMAC_Update(hctx, &resp[POS_ATTRS],
                                    h->in_len - POS_ATTRS);
                                HMAC_Final(hctx, md, &md_len);
                                HMAC_CTX_reset(hctx);
                                if (memcmp(md, &h->in[pos + 2],
                                    MD5_DIGEST_LENGTH) != 0) {
                                        HMAC_CTX_free(hctx);
                                        return 0;
                                }
                                break;
                        }
                        alen = h->in[pos + 1];
                        if (alen < 2) {
                                HMAC_CTX_free(hctx);
                                return 0;
                        }
                        pos += alen;
                }
                HMAC_CTX_free(hctx);
        }
#endif
        return 1;
}

/*
 * Return true if the current request is valid for the specified server.
 */
static int
is_valid_request(struct rad_handle *h)
{
        MD5_CTX ctx;
        unsigned char md5[MD5_DIGEST_LENGTH];
        const struct rad_server *srvp;
        int len;
#ifdef WITH_SSL
        int alen;
        HMAC_CTX *hctx;
        u_char resp[MSGSIZE], md[EVP_MAX_MD_SIZE];
        u_int md_len;
        int pos;
#endif

        srvp = &h->servers[h->srv];

        /* Check the message length */
        if (h->in_len < POS_ATTRS)
                return (0);
        len = (h->in[POS_LENGTH] << 8) | h->in[POS_LENGTH + 1];
        if (len < POS_ATTRS || len > h->in_len)
                return (0);

        if (h->in[POS_CODE] != RAD_ACCESS_REQUEST) {
                uint32_t zeroes[4] = { 0, 0, 0, 0 };
                /* Check the request authenticator */
                MD5Init(&ctx);
                MD5Update(&ctx, &h->in[POS_CODE], POS_AUTH - POS_CODE);
                MD5Update(&ctx, zeroes, LEN_AUTH);
                MD5Update(&ctx, &h->in[POS_ATTRS], len - POS_ATTRS);
                MD5Update(&ctx, srvp->secret, strlen(srvp->secret));
                MD5Final(md5, &ctx);
                if (memcmp(&h->in[POS_AUTH], md5, sizeof md5) != 0)
                        return (0);
        }

#ifdef WITH_SSL
        /* Search and verify the Message-Authenticator */
        pos = POS_ATTRS;
        hctx = HMAC_CTX_new();
        while (pos < len - 2) {
                alen = h->in[pos + 1];
                if (alen < 2) {
                        HMAC_CTX_free(hctx);
                        return (0);
                }
                if (h->in[pos] == RAD_MESSAGE_AUTHENTIC) {
                        if (len - pos < MD5_DIGEST_LENGTH + 2) {
                                HMAC_CTX_free(hctx);
                                return (0);
                        }
                        if (alen < MD5_DIGEST_LENGTH + 2) {
                                HMAC_CTX_free(hctx);
                                return (0);
                        }
                        memcpy(resp, h->in, MSGSIZE);
                        /* zero fill the Request-Authenticator */
                        if (h->in[POS_CODE] != RAD_ACCESS_REQUEST)
                                memset(&resp[POS_AUTH], 0, LEN_AUTH);
                        /* zero fill the Message-Authenticator */
                        memset(&resp[pos + 2], 0, MD5_DIGEST_LENGTH);

                        HMAC_Init_ex(hctx, srvp->secret,
                            strlen(srvp->secret), EVP_md5(), NULL);
                        HMAC_Update(hctx, resp, h->in_len);
                        HMAC_Final(hctx, md, &md_len);
                        HMAC_CTX_reset(hctx);
                        if (memcmp(md, &h->in[pos + 2],
                            MD5_DIGEST_LENGTH) != 0) {
                                HMAC_CTX_free(hctx);
                                return (0);
                        }
                        break;
                }
                pos += alen;
        }
        HMAC_CTX_free(hctx);
#endif
        return (1);
}

static int
put_password_attr(struct rad_handle *h, int type, const void *value, size_t len)
{
        int padded_len;
        int pad_len;

        if (h->pass_pos != 0) {
                generr(h, "Multiple User-Password attributes specified");
                return -1;
        }
        if (len > PASSSIZE)
                len = PASSSIZE;
        padded_len = len == 0 ? 16 : (len+15) & ~0xf;
        pad_len = padded_len - len;

        /*
         * Put in a place-holder attribute containing all zeros, and
         * remember where it is so we can fill it in later.
         */
        clear_password(h);
        put_raw_attr(h, type, h->pass, padded_len);
        h->pass_pos = h->out_len - padded_len;

        /* Save the cleartext password, padded as necessary */
        memcpy(h->pass, value, len);
        h->pass_len = len;
        memset(h->pass + len, 0, pad_len);
        return 0;
}

static int
put_raw_attr(struct rad_handle *h, int type, const void *value, size_t len)
{
        if (len > 253) {
                generr(h, "Attribute too long");
                return -1;
        }
        if (h->out_len + 2 + len > MSGSIZE) {
                generr(h, "Maximum message length exceeded");
                return -1;
        }
        h->out[h->out_len++] = type;
        h->out[h->out_len++] = len + 2;
        memcpy(&h->out[h->out_len], value, len);
        h->out_len += len;
        return 0;
}

int
rad_add_server(struct rad_handle *h, const char *host, int port,
    const char *secret, int timeout, int tries)
{
        struct in_addr bindto;
        bindto.s_addr = INADDR_ANY;

        return rad_add_server_ex(h, host, port, secret, timeout, tries,
                DEAD_TIME, &bindto);
}

int
rad_add_server_ex(struct rad_handle *h, const char *host, int port,
    const char *secret, int timeout, int tries, int dead_time,
    struct in_addr *bindto)
{
        struct rad_server *srvp;

        if (h->num_servers >= MAXSERVERS) {
                generr(h, "Too many RADIUS servers specified");
                return -1;
        }
        srvp = &h->servers[h->num_servers];

        memset(&srvp->addr, 0, sizeof srvp->addr);
        srvp->addr.sin_len = sizeof srvp->addr;
        srvp->addr.sin_family = AF_INET;
        if (!inet_aton(host, &srvp->addr.sin_addr)) {
                struct hostent *hent;

                if ((hent = gethostbyname(host)) == NULL) {
                        generr(h, "%s: host not found", host);
                        return -1;
                }
                memcpy(&srvp->addr.sin_addr, hent->h_addr,
                    sizeof srvp->addr.sin_addr);
        }
        if (port != 0)
                srvp->addr.sin_port = htons((u_short)port);
        else {
                struct servent *sent;

                if (h->type == RADIUS_AUTH)
                        srvp->addr.sin_port =
                            (sent = getservbyname("radius", "udp")) != NULL ?
                                sent->s_port : htons(RADIUS_PORT);
                else
                        srvp->addr.sin_port =
                            (sent = getservbyname("radacct", "udp")) != NULL ?
                                sent->s_port : htons(RADACCT_PORT);
        }
        if ((srvp->secret = strdup(secret)) == NULL) {
                generr(h, "Out of memory");
                return -1;
        }
        srvp->timeout = timeout;
        srvp->max_tries = tries;
        srvp->num_tries = 0;
        srvp->is_dead = 0;
        srvp->dead_time = dead_time;
        srvp->next_probe = 0;
        srvp->bindto = bindto->s_addr;
        h->num_servers++;
        return 0;
}

void
rad_close(struct rad_handle *h)
{
        int srv;

        if (h->fd != -1)
                close(h->fd);
        for (srv = 0;  srv < h->num_servers;  srv++) {
                memset(h->servers[srv].secret, 0,
                    strlen(h->servers[srv].secret));
                free(h->servers[srv].secret);
        }
        clear_password(h);
        free(h);
}

void
rad_bind_to(struct rad_handle *h, in_addr_t addr)
{

        h->bindto = addr;
}

int
rad_config(struct rad_handle *h, const char *path)
{
        FILE *fp;
        char buf[MAXCONFLINE];
        int linenum;
        int retval;

        if (path == NULL)
                path = PATH_RADIUS_CONF;
        if ((fp = fopen(path, "r")) == NULL) {
                generr(h, "Cannot open \"%s\": %s", path, strerror(errno));
                return -1;
        }
        retval = 0;
        linenum = 0;
        while (fgets(buf, sizeof buf, fp) != NULL) {
                int len;
                char *fields[MAX_FIELDS];
                int nfields;
                char msg[ERRSIZE];
                char *type;
                char *host, *res;
                char *port_str;
                char *secret;
                char *timeout_str;
                char *maxtries_str;
                char *dead_time_str;
                char *bindto_str;
                char *end;
                char *wanttype;
                unsigned long timeout;
                unsigned long maxtries;
                unsigned long dead_time;
                int port;
                struct in_addr bindto;
                int i;

                linenum++;
                len = strlen(buf);
                /* We know len > 0, else fgets would have returned NULL. */
                if (buf[len - 1] != '\n') {
                        if (len == sizeof buf - 1)
                                generr(h, "%s:%d: line too long", path,
                                    linenum);
                        else
                                generr(h, "%s:%d: missing newline", path,
                                    linenum);
                        retval = -1;
                        break;
                }
                buf[len - 1] = '\0';

                /* Extract the fields from the line. */
                nfields = split(buf, fields, MAX_FIELDS, msg, sizeof msg);
                if (nfields == -1) {
                        generr(h, "%s:%d: %s", path, linenum, msg);
                        retval = -1;
                        break;
                }
                if (nfields == 0)
                        continue;
                /*
                 * The first field should contain "auth" or "acct" for
                 * authentication or accounting, respectively.  But older
                 * versions of the file didn't have that field.  Default
                 * it to "auth" for backward compatibility.
                 */
                if (strcmp(fields[0], "auth") != 0 &&
                    strcmp(fields[0], "acct") != 0) {
                        if (nfields >= MAX_FIELDS) {
                                generr(h, "%s:%d: invalid service type", path,
                                    linenum);
                                retval = -1;
                                break;
                        }
                        nfields++;
                        for (i = nfields;  --i > 0;  )
                                fields[i] = fields[i - 1];
                        fields[0] = "auth";
                }
                if (nfields < 3) {
                        generr(h, "%s:%d: missing shared secret", path,
                            linenum);
                        retval = -1;
                        break;
                }
                type = fields[0];
                host = fields[1];
                secret = fields[2];
                timeout_str = fields[3];
                maxtries_str = fields[4];
                dead_time_str = fields[5];
                bindto_str = fields[6];

                /* Ignore the line if it is for the wrong service type. */
                wanttype = h->type == RADIUS_AUTH ? "auth" : "acct";
                if (strcmp(type, wanttype) != 0)
                        continue;

                /* Parse and validate the fields. */
                res = host;
                host = strsep(&res, ":");
                port_str = strsep(&res, ":");
                if (port_str != NULL) {
                        port = strtoul(port_str, &end, 10);
                        if (*end != '\0') {
                                generr(h, "%s:%d: invalid port", path,
                                    linenum);
                                retval = -1;
                                break;
                        }
                } else
                        port = 0;
                if (timeout_str != NULL) {
                        timeout = strtoul(timeout_str, &end, 10);
                        if (*end != '\0') {
                                generr(h, "%s:%d: invalid timeout", path,
                                    linenum);
                                retval = -1;
                                break;
                        }
                } else
                        timeout = TIMEOUT;
                if (maxtries_str != NULL) {
                        maxtries = strtoul(maxtries_str, &end, 10);
                        if (*end != '\0') {
                                generr(h, "%s:%d: invalid maxtries", path,
                                    linenum);
                                retval = -1;
                                break;
                        }
                } else
                        maxtries = MAXTRIES;

                if (dead_time_str != NULL) {
                        dead_time = strtoul(dead_time_str, &end, 10);
                        if (*end != '\0') {
                                generr(h, "%s:%d: invalid dead_time", path,
                                    linenum);
                                retval = -1;
                                break;
                        }
                } else
                        dead_time = DEAD_TIME;

                if (bindto_str != NULL) {
                        bindto.s_addr = inet_addr(bindto_str);
                        if (bindto.s_addr == INADDR_NONE) {
                                generr(h, "%s:%d: invalid bindto", path,
                                    linenum);
                                retval = -1;
                                break;
                        }
                } else
                        bindto.s_addr = INADDR_ANY;

                if (rad_add_server_ex(h, host, port, secret, timeout, maxtries,
                            dead_time, &bindto) == -1) {
                        strcpy(msg, h->errmsg);
                        generr(h, "%s:%d: %s", path, linenum, msg);
                        retval = -1;
                        break;
                }
        }
        /* Clear out the buffer to wipe a possible copy of a shared secret */
        memset(buf, 0, sizeof buf);
        fclose(fp);
        return retval;
}

/*
 * rad_init_send_request() must have previously been called.
 * Returns:
 *   0     The application should select on *fd with a timeout of tv before
 *         calling rad_continue_send_request again.
 *   < 0   Failure
 *   > 0   Success
 */
int
rad_continue_send_request(struct rad_handle *h, int selected, int *fd,
                          struct timeval *tv)
{
        int n, cur_srv;
        time_t now;
        struct sockaddr_in sin;

        if (h->type == RADIUS_SERVER) {
                generr(h, "denied function call");
                return (-1);
        }
        if (selected) {
                struct sockaddr_in from;
                socklen_t fromlen;

                fromlen = sizeof from;
                h->in_len = recvfrom(h->fd, h->in,
                    MSGSIZE, MSG_WAITALL, (struct sockaddr *)&from, &fromlen);
                if (h->in_len == -1) {
                        generr(h, "recvfrom: %s", strerror(errno));
                        return -1;
                }
                if (is_valid_response(h, h->srv, &from)) {
                        h->in_len = h->in[POS_LENGTH] << 8 |
                            h->in[POS_LENGTH+1];
                        h->in_pos = POS_ATTRS;
                        return h->in[POS_CODE];
                }
        }

        /*
         * Scan round-robin to the next server that has some
         * tries left.  There is guaranteed to be one, or we
         * would have exited this loop by now.
         */
        cur_srv = h->srv;
        now = time(NULL);
        if (h->servers[h->srv].num_tries >= h->servers[h->srv].max_tries) {
                /* Set next probe time for this server */
                if (h->servers[h->srv].dead_time) {
                        h->servers[h->srv].is_dead = 1;
                        h->servers[h->srv].next_probe = now +
                            h->servers[h->srv].dead_time;
                }
                do {
                        h->srv++;
                        if (h->srv >= h->num_servers)
                                h->srv = 0;
                        if (h->servers[h->srv].is_dead == 0)
                                break;
                        if (h->servers[h->srv].dead_time &&
                            h->servers[h->srv].next_probe <= now) {
                                h->servers[h->srv].is_dead = 0;
                                h->servers[h->srv].num_tries = 0;
                                break;
                        }
                } while (h->srv != cur_srv);

                if (h->srv == cur_srv) {
                        generr(h, "No valid RADIUS responses received");
                        return (-1);
                }
        }

        /* Rebind */
        if (h->bindto != h->servers[h->srv].bindto) {
                h->bindto = h->servers[h->srv].bindto;
                close(h->fd);
                if ((h->fd = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP)) == -1) {
                        generr(h, "Cannot create socket: %s", strerror(errno));
                        return -1;
                }
                memset(&sin, 0, sizeof sin);
                sin.sin_len = sizeof sin;
                sin.sin_family = AF_INET;
                sin.sin_addr.s_addr = h->bindto;
                sin.sin_port = 0;
                if (bind(h->fd, (const struct sockaddr *)&sin,
                    sizeof sin) == -1) {
                        generr(h, "bind: %s", strerror(errno));
                        close(h->fd);
                        h->fd = -1;
                        return (-1);
                }
        }

        if (h->out[POS_CODE] == RAD_ACCESS_REQUEST) {
                /* Insert the scrambled password into the request */
                if (h->pass_pos != 0)
                        insert_scrambled_password(h, h->srv);
        }
        insert_message_authenticator(h, 0);

        if (h->out[POS_CODE] != RAD_ACCESS_REQUEST) {
                /* Insert the request authenticator into the request */
                memset(&h->out[POS_AUTH], 0, LEN_AUTH);
                insert_request_authenticator(h, 0);
        }

        /* Send the request */
        n = sendto(h->fd, h->out, h->out_len, 0,
            (const struct sockaddr *)&h->servers[h->srv].addr,
            sizeof h->servers[h->srv].addr);
        if (n != h->out_len)
                tv->tv_sec = 1; /* Do not wait full timeout if send failed. */
        else
                tv->tv_sec = h->servers[h->srv].timeout;
        h->servers[h->srv].num_tries++;
        tv->tv_usec = 0;
        *fd = h->fd;

        return 0;
}

int
rad_receive_request(struct rad_handle *h)
{
        struct sockaddr_in from;
        socklen_t fromlen;
        int n;

        if (h->type != RADIUS_SERVER) {
                generr(h, "denied function call");
                return (-1);
        }
        h->srv = -1;
        fromlen = sizeof(from);
        h->in_len = recvfrom(h->fd, h->in,
            MSGSIZE, MSG_WAITALL, (struct sockaddr *)&from, &fromlen);
        if (h->in_len == -1) {
                generr(h, "recvfrom: %s", strerror(errno));
                return (-1);
        }
        for (n = 0; n < h->num_servers; n++) {
                if (h->servers[n].addr.sin_addr.s_addr == from.sin_addr.s_addr) {
                        h->servers[n].addr.sin_port = from.sin_port;
                        h->srv = n;
                        break;
                }
        }
        if (h->srv == -1)
                return (-2);
        if (is_valid_request(h)) {
                h->in_len = h->in[POS_LENGTH] << 8 |
                    h->in[POS_LENGTH+1];
                h->in_pos = POS_ATTRS;
                return (h->in[POS_CODE]);
        }
        return (-3);
}

int
rad_send_response(struct rad_handle *h)
{
        int n;

        if (h->type != RADIUS_SERVER) {
                generr(h, "denied function call");
                return (-1);
        }
        /* Fill in the length field in the message */
        h->out[POS_LENGTH] = h->out_len >> 8;
        h->out[POS_LENGTH+1] = h->out_len;

        insert_message_authenticator(h,
            (h->in[POS_CODE] == RAD_ACCESS_REQUEST) ? 1 : 0);
        insert_request_authenticator(h, 1);

        /* Send the request */
        n = sendto(h->fd, h->out, h->out_len, 0,
            (const struct sockaddr *)&h->servers[h->srv].addr,
            sizeof h->servers[h->srv].addr);
        if (n != h->out_len) {
                if (n == -1)
                        generr(h, "sendto: %s", strerror(errno));
                else
                        generr(h, "sendto: short write");
                return -1;
        }

        return 0;
}

int
rad_create_request(struct rad_handle *h, int code)
{
        int i;

        if (h->type == RADIUS_SERVER) {
                generr(h, "denied function call");
                return (-1);
        }
        if (h->num_servers == 0) {
                generr(h, "No RADIUS servers specified");
                return (-1);
        }
        h->out[POS_CODE] = code;
        h->out[POS_IDENT] = ++h->ident;
        if (code == RAD_ACCESS_REQUEST) {
                /* Create a random authenticator */
                for (i = 0;  i < LEN_AUTH;  i += 2) {
                        uint32_t r;
                        r = arc4random();
                        h->out[POS_AUTH+i] = (u_char)r;
                        h->out[POS_AUTH+i+1] = (u_char)(r >> 8);
                }
        } else
                memset(&h->out[POS_AUTH], 0, LEN_AUTH);
        h->out_len = POS_ATTRS;
        clear_password(h);
        h->authentic_pos = 0;
        h->out_created = 1;
        return 0;
}

int
rad_create_response(struct rad_handle *h, int code)
{

        if (h->type != RADIUS_SERVER) {
                generr(h, "denied function call");
                return (-1);
        }
        h->out[POS_CODE] = code;
        h->out[POS_IDENT] = h->in[POS_IDENT];
        memset(&h->out[POS_AUTH], 0, LEN_AUTH);
        h->out_len = POS_ATTRS;
        clear_password(h);
        h->authentic_pos = 0;
        h->out_created = 1;
        return 0;
}

struct in_addr
rad_cvt_addr(const void *data)
{
        struct in_addr value;

        memcpy(&value.s_addr, data, sizeof value.s_addr);
        return value;
}

struct in6_addr
rad_cvt_addr6(const void *data)
{
        struct in6_addr value;

        memcpy(&value.s6_addr, data, sizeof value.s6_addr);
        return value;
}

u_int32_t
rad_cvt_int(const void *data)
{
        u_int32_t value;

        memcpy(&value, data, sizeof value);
        return ntohl(value);
}

char *
rad_cvt_string(const void *data, size_t len)
{
        char *s;

        s = malloc(len + 1);
        if (s != NULL) {
                memcpy(s, data, len);
                s[len] = '\0';
        }
        return s;
}

/*
 * Returns the attribute type.  If none are left, returns 0.  On failure,
 * returns -1.
 */
int
rad_get_attr(struct rad_handle *h, const void **value, size_t *lenp)
{
        int len, type;

        if (h->in_pos >= h->in_len)
                return 0;
        if (h->in_pos + 2 > h->in_len) {
                generr(h, "Malformed attribute in response");
                return -1;
        }
        type = h->in[h->in_pos++];
        len = h->in[h->in_pos++];
        if (len < 2) {
                generr(h, "Malformed attribute in response");
                return -1;
        }
        len -= 2;
        if (h->in_pos + len > h->in_len) {
                generr(h, "Malformed attribute in response");
                return -1;
        }
        *lenp = len;
        *value = &h->in[h->in_pos];
        h->in_pos += len;
        return type;
}

/*
 * Returns -1 on error, 0 to indicate no event and >0 for success
 */
int
rad_init_send_request(struct rad_handle *h, int *fd, struct timeval *tv)
{
        int srv;
        time_t now;
        struct sockaddr_in sin;

        if (h->type == RADIUS_SERVER) {
                generr(h, "denied function call");
                return (-1);
        }
        /* Make sure we have a socket to use */
        if (h->fd == -1) {
                if ((h->fd = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP)) == -1) {
                        generr(h, "Cannot create socket: %s", strerror(errno));
                        return -1;
                }
                memset(&sin, 0, sizeof sin);
                sin.sin_len = sizeof sin;
                sin.sin_family = AF_INET;
                sin.sin_addr.s_addr = h->bindto;
                sin.sin_port = htons(0);
                if (bind(h->fd, (const struct sockaddr *)&sin,
                    sizeof sin) == -1) {
                        generr(h, "bind: %s", strerror(errno));
                        close(h->fd);
                        h->fd = -1;
                        return -1;
                }
        }

        if (h->out[POS_CODE] != RAD_ACCESS_REQUEST) {
                /* Make sure no password given */
                if (h->pass_pos || h->chap_pass) {
                        generr(h, "User or Chap Password"
                            " in accounting request");
                        return -1;
                }
        } else {
                if (h->eap_msg == 0) {
                        /* Make sure the user gave us a password */
                        if (h->pass_pos == 0 && !h->chap_pass) {
                                generr(h, "No User or Chap Password"
                                    " attributes given");
                                return -1;
                        }
                        if (h->pass_pos != 0 && h->chap_pass) {
                                generr(h, "Both User and Chap Password"
                                    " attributes given");
                                return -1;
                        }
                }
        }

        /* Fill in the length field in the message */
        h->out[POS_LENGTH] = h->out_len >> 8;
        h->out[POS_LENGTH+1] = h->out_len;

        h->srv = 0;
        now = time(NULL);
        for (srv = 0;  srv < h->num_servers;  srv++)
                h->servers[srv].num_tries = 0;
        /* Find a first good server. */
        for (srv = 0;  srv < h->num_servers;  srv++) {
                if (h->servers[srv].is_dead == 0)
                        break;
                if (h->servers[srv].dead_time &&
                    h->servers[srv].next_probe <= now) {
                        h->servers[srv].is_dead = 0;
                        break;
                }
                h->srv++;
        }

        /* If all servers was dead on the last probe, try from beginning */
        if (h->srv == h->num_servers) {
                for (srv = 0;  srv < h->num_servers;  srv++) {
                        h->servers[srv].is_dead = 0;
                        h->servers[srv].next_probe = 0;
                }
                h->srv = 0;
        }

        return rad_continue_send_request(h, 0, fd, tv);
}

/*
 * Create and initialize a rad_handle structure, and return it to the
 * caller.  Can fail only if the necessary memory cannot be allocated.
 * In that case, it returns NULL.
 */
struct rad_handle *
rad_auth_open(void)
{
        struct rad_handle *h;

        h = (struct rad_handle *)malloc(sizeof(struct rad_handle));
        if (h != NULL) {
                h->fd = -1;
                h->num_servers = 0;
                h->ident = arc4random();
                h->errmsg[0] = '\0';
                memset(h->pass, 0, sizeof h->pass);
                h->pass_len = 0;
                h->pass_pos = 0;
                h->chap_pass = 0;
                h->authentic_pos = 0;
                h->type = RADIUS_AUTH;
                h->out_created = 0;
                h->eap_msg = 0;
                h->bindto = INADDR_ANY;
        }
        return h;
}

struct rad_handle *
rad_acct_open(void)
{
        struct rad_handle *h;

        h = rad_open();
        if (h != NULL)
                h->type = RADIUS_ACCT;
        return h;
}

struct rad_handle *
rad_server_open(int fd)
{
        struct rad_handle *h;

        h = rad_open();
        if (h != NULL) {
                h->type = RADIUS_SERVER;
                h->fd = fd;
        }
        return h;
}

struct rad_handle *
rad_open(void)
{
    return rad_auth_open();
}

int
rad_put_addr(struct rad_handle *h, int type, struct in_addr addr)
{
        return rad_put_attr(h, type, &addr.s_addr, sizeof addr.s_addr);
}

int
rad_put_addr6(struct rad_handle *h, int type, struct in6_addr addr)
{

        return rad_put_attr(h, type, &addr.s6_addr, sizeof addr.s6_addr);
}

int
rad_put_attr(struct rad_handle *h, int type, const void *value, size_t len)
{
        int result;

        if (!h->out_created) {
                generr(h, "Please call rad_create_request()"
                    " before putting attributes");
                return -1;
        }

        if (h->out[POS_CODE] == RAD_ACCOUNTING_REQUEST) {
                if (type == RAD_EAP_MESSAGE) {
                        generr(h, "EAP-Message attribute is not valid"
                            " in accounting requests");
                        return -1;
                }
        }

        /*
         * When proxying EAP Messages, the Message Authenticator
         * MUST be present; see RFC 3579.
         */
        if (type == RAD_EAP_MESSAGE) {
                if (rad_put_message_authentic(h) == -1)
                        return -1;
        }

        if (type == RAD_USER_PASSWORD) {
                result = put_password_attr(h, type, value, len);
        } else if (type == RAD_MESSAGE_AUTHENTIC) {
                result = rad_put_message_authentic(h);
        } else {
                result = put_raw_attr(h, type, value, len);
                if (result == 0) {
                        if (type == RAD_CHAP_PASSWORD)
                                h->chap_pass = 1;
                        else if (type == RAD_EAP_MESSAGE)
                                h->eap_msg = 1;
                }
        }

        return result;
}

int
rad_put_int(struct rad_handle *h, int type, u_int32_t value)
{
        u_int32_t nvalue;

        nvalue = htonl(value);
        return rad_put_attr(h, type, &nvalue, sizeof nvalue);
}

int
rad_put_string(struct rad_handle *h, int type, const char *str)
{
        return rad_put_attr(h, type, str, strlen(str));
}

int
rad_put_message_authentic(struct rad_handle *h)
{
#ifdef WITH_SSL
        u_char md_zero[MD5_DIGEST_LENGTH];

        if (h->out[POS_CODE] == RAD_ACCOUNTING_REQUEST) {
                generr(h, "Message-Authenticator is not valid"
                    " in accounting requests");
                return -1;
        }

        if (h->authentic_pos == 0) {
                h->authentic_pos = h->out_len;
                memset(md_zero, 0, sizeof(md_zero));
                return (put_raw_attr(h, RAD_MESSAGE_AUTHENTIC, md_zero,
                    sizeof(md_zero)));
        }
        return 0;
#else
        generr(h, "Message Authenticator not supported,"
            " please recompile libradius with SSL support");
        return -1;
#endif
}

/*
 * Returns the response type code on success, or -1 on failure.
 */
int
rad_send_request(struct rad_handle *h)
{
        struct timeval timelimit;
        struct timeval tv;
        int fd;
        int n;

        n = rad_init_send_request(h, &fd, &tv);

        if (n != 0)
                return n;

        gettimeofday(&timelimit, NULL);
        timeradd(&tv, &timelimit, &timelimit);

        for ( ; ; ) {
                fd_set readfds;

                FD_ZERO(&readfds);
                FD_SET(fd, &readfds);

                n = select(fd + 1, &readfds, NULL, NULL, &tv);

                if (n == -1) {
                        generr(h, "select: %s", strerror(errno));
                        return -1;
                }

                if (!FD_ISSET(fd, &readfds)) {
                        /* Compute a new timeout */
                        gettimeofday(&tv, NULL);
                        timersub(&timelimit, &tv, &tv);
                        if (tv.tv_sec > 0 || (tv.tv_sec == 0 && tv.tv_usec > 0))
                                /* Continue the select */
                                continue;
                }

                n = rad_continue_send_request(h, n, &fd, &tv);

                if (n != 0)
                        return n;

                gettimeofday(&timelimit, NULL);
                timeradd(&tv, &timelimit, &timelimit);
        }
}

const char *
rad_strerror(struct rad_handle *h)
{
        return h->errmsg;
}

/*
 * Destructively split a string into fields separated by white space.
 * `#' at the beginning of a field begins a comment that extends to the
 * end of the string.  Fields may be quoted with `"'.  Inside quoted
 * strings, the backslash escapes `\"' and `\\' are honored.
 *
 * Pointers to up to the first maxfields fields are stored in the fields
 * array.  Missing fields get NULL pointers.
 *
 * The return value is the actual number of fields parsed, and is always
 * <= maxfields.
 *
 * On a syntax error, places a message in the msg string, and returns -1.
 */
static int
split(char *str, char *fields[], int maxfields, char *msg, size_t msglen)
{
        char *p;
        int i;
        static const char ws[] = " \t";

        for (i = 0;  i < maxfields;  i++)
                fields[i] = NULL;
        p = str;
        i = 0;
        while (*p != '\0') {
                p += strspn(p, ws);
                if (*p == '#' || *p == '\0')
                        break;
                if (i >= maxfields) {
                        snprintf(msg, msglen, "line has too many fields");
                        return -1;
                }
                if (*p == '"') {
                        char *dst;

                        dst = ++p;
                        fields[i] = dst;
                        while (*p != '"') {
                                if (*p == '\\') {
                                        p++;
                                        if (*p != '"' && *p != '\\' &&
                                            *p != '\0') {
                                                snprintf(msg, msglen,
                                                    "invalid `\\' escape");
                                                return -1;
                                        }
                                }
                                if (*p == '\0') {
                                        snprintf(msg, msglen,
                                            "unterminated quoted string");
                                        return -1;
                                }
                                *dst++ = *p++;
                        }
                        *dst = '\0';
                        p++;
                        if (*fields[i] == '\0') {
                                snprintf(msg, msglen,
                                    "empty quoted string not permitted");
                                return -1;
                        }
                        if (*p != '\0' && strspn(p, ws) == 0) {
                                snprintf(msg, msglen, "quoted string not"
                                    " followed by white space");
                                return -1;
                        }
                } else {
                        fields[i] = p;
                        p += strcspn(p, ws);
                        if (*p != '\0')
                                *p++ = '\0';
                }
                i++;
        }
        return i;
}

int
rad_get_vendor_attr(u_int32_t *vendor, const void **data, size_t *len)
{
        struct vendor_attribute *attr;

        attr = (struct vendor_attribute *)*data;
        *vendor = ntohl(attr->vendor_value);
        *data = attr->attrib_data;
        *len = attr->attrib_len - 2;

        return (attr->attrib_type);
}

int
rad_put_vendor_addr(struct rad_handle *h, int vendor, int type,
    struct in_addr addr)
{
        return (rad_put_vendor_attr(h, vendor, type, &addr.s_addr,
            sizeof addr.s_addr));
}

int
rad_put_vendor_addr6(struct rad_handle *h, int vendor, int type,
    struct in6_addr addr)
{

        return (rad_put_vendor_attr(h, vendor, type, &addr.s6_addr,
            sizeof addr.s6_addr));
}

int
rad_put_vendor_attr(struct rad_handle *h, int vendor, int type,
    const void *value, size_t len)
{
        struct vendor_attribute *attr;
        int res;

        if (!h->out_created) {
                generr(h, "Please call rad_create_request()"
                    " before putting attributes");
                return -1;
        }

        if ((attr = malloc(len + 6)) == NULL) {
                generr(h, "malloc failure (%zu bytes)", len + 6);
                return -1;
        }

        attr->vendor_value = htonl(vendor);
        attr->attrib_type = type;
        attr->attrib_len = len + 2;
        memcpy(attr->attrib_data, value, len);

        res = put_raw_attr(h, RAD_VENDOR_SPECIFIC, attr, len + 6);
        free(attr);
        if (res == 0 && vendor == RAD_VENDOR_MICROSOFT
            && (type == RAD_MICROSOFT_MS_CHAP_RESPONSE
            || type == RAD_MICROSOFT_MS_CHAP2_RESPONSE)) {
                h->chap_pass = 1;
        }
        return (res);
}

int
rad_put_vendor_int(struct rad_handle *h, int vendor, int type, u_int32_t i)
{
        u_int32_t value;

        value = htonl(i);
        return (rad_put_vendor_attr(h, vendor, type, &value, sizeof value));
}

int
rad_put_vendor_string(struct rad_handle *h, int vendor, int type,
    const char *str)
{
        return (rad_put_vendor_attr(h, vendor, type, str, strlen(str)));
}

ssize_t
rad_request_authenticator(struct rad_handle *h, char *buf, size_t len)
{
        if (len < LEN_AUTH)
                return (-1);
        memcpy(buf, h->out + POS_AUTH, LEN_AUTH);
        if (len > LEN_AUTH)
                buf[LEN_AUTH] = '\0';
        return (LEN_AUTH);
}

u_char *
rad_demangle(struct rad_handle *h, const void *mangled, size_t mlen)
{
        char R[LEN_AUTH];
        const char *S;
        int i, Ppos;
        MD5_CTX Context;
        u_char b[MD5_DIGEST_LENGTH], *C, *demangled;

        if ((mlen % 16 != 0) || mlen > 128) {
                generr(h, "Cannot interpret mangled data of length %lu",
                    (u_long)mlen);
                return NULL;
        }

        C = (u_char *)mangled;

        /* We need the shared secret as Salt */
        S = rad_server_secret(h);

        /* We need the request authenticator */
        if (rad_request_authenticator(h, R, sizeof R) != LEN_AUTH) {
                generr(h, "Cannot obtain the RADIUS request authenticator");
                return NULL;
        }

        demangled = malloc(mlen);
        if (!demangled)
                return NULL;

        MD5Init(&Context);
        MD5Update(&Context, S, strlen(S));
        MD5Update(&Context, R, LEN_AUTH);
        MD5Final(b, &Context);
        Ppos = 0;
        while (mlen) {

                mlen -= 16;
                for (i = 0; i < 16; i++)
                        demangled[Ppos++] = C[i] ^ b[i];

                if (mlen) {
                        MD5Init(&Context);
                        MD5Update(&Context, S, strlen(S));
                        MD5Update(&Context, C, 16);
                        MD5Final(b, &Context);
                }

                C += 16;
        }

        return demangled;
}

u_char *
rad_demangle_mppe_key(struct rad_handle *h, const void *mangled,
    size_t mlen, size_t *len)
{
        char R[LEN_AUTH];    /* variable names as per rfc2548 */
        const char *S;
        u_char b[MD5_DIGEST_LENGTH], *demangled;
        const u_char *A, *C;
        MD5_CTX Context;
        int Slen, i, Clen, Ppos;
        u_char *P;

        if (mlen % 16 != SALT_LEN) {
                generr(h, "Cannot interpret mangled data of length %lu",
                    (u_long)mlen);
                return NULL;
        }

        /* We need the RADIUS Request-Authenticator */
        if (rad_request_authenticator(h, R, sizeof R) != LEN_AUTH) {
                generr(h, "Cannot obtain the RADIUS request authenticator");
                return NULL;
        }

        A = (const u_char *)mangled;      /* Salt comes first */
        C = (const u_char *)mangled + SALT_LEN;  /* Then the ciphertext */
        Clen = mlen - SALT_LEN;
        S = rad_server_secret(h);    /* We need the RADIUS secret */
        Slen = strlen(S);
        P = alloca(Clen);        /* We derive our plaintext */

        MD5Init(&Context);
        MD5Update(&Context, S, Slen);
        MD5Update(&Context, R, LEN_AUTH);
        MD5Update(&Context, A, SALT_LEN);
        MD5Final(b, &Context);
        Ppos = 0;

        while (Clen) {
                Clen -= 16;

                for (i = 0; i < 16; i++)
                    P[Ppos++] = C[i] ^ b[i];

                if (Clen) {
                        MD5Init(&Context);
                        MD5Update(&Context, S, Slen);
                        MD5Update(&Context, C, 16);
                        MD5Final(b, &Context);
                }

                C += 16;
        }

        /*
        * The resulting plain text consists of a one-byte length, the text and
        * maybe some padding.
        */
        *len = *P;
        if (*len > mlen - 1) {
                generr(h, "Mangled data seems to be garbage %zu %zu",
                    *len, mlen-1);
                return NULL;
        }

        if (*len > MPPE_KEY_LEN * 2) {
                generr(h, "Key to long (%zu) for me max. %d",
                    *len, MPPE_KEY_LEN * 2);
                return NULL;
        }
        demangled = malloc(*len);
        if (!demangled)
                return NULL;

        memcpy(demangled, P + 1, *len);
        return demangled;
}

const char *
rad_server_secret(struct rad_handle *h)
{
        return (h->servers[h->srv].secret);
}