radsecproxy.c

/*
 * Copyright (C) 2006, 2007 Stig Venaas <venaas@uninett.no>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 */

/* For UDP there is one server instance consisting of udpserverrd and udpserverth
 *              rd is responsible for init and launching wr
 * For TLS there is a server instance that launches tlsserverrd for each TLS peer
 *          each tlsserverrd launches tlsserverwr
 * For each UDP/TLS peer there is clientrd and clientwr, clientwr is responsible
 *          for init and launching rd
 *
 * serverrd will receive a request, processes it and puts it in the requestq of
 *          the appropriate clientwr
 * clientwr monitors its requestq and sends requests
 * clientrd looks for responses, processes them and puts them in the replyq of
 *          the peer the request came from
 * serverwr monitors its reply and sends replies
 *
 * In addition to the main thread, we have:
 * If UDP peers are configured, there will be 2 + 2 * #peers UDP threads
 * If TLS peers are configured, there will initially be 2 * #peers TLS threads
 * For each TLS peer connecting to us there will be 2 more TLS threads
 *       This is only for connected peers
 * Example: With 3 UDP peer and 30 TLS peers, there will be a max of
 *          1 + (2 + 2 * 3) + (2 * 30) + (2 * 30) = 129 threads
*/

#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <string.h>
#include <unistd.h>
#include <sys/time.h>
#include <regex.h>
#include <libgen.h>
#include <pthread.h>
#include <openssl/ssl.h>
#include <openssl/rand.h>
#include <openssl/err.h>
#include <openssl/md5.h>
#include <openssl/hmac.h>
#include "debug.h"
#include "list.h"
#include "radsecproxy.h"

static struct options options;
struct list *clconfs, *srvconfs, *realms, *tls;

static int client_udp_count = 0;
static int client_tls_count = 0;
static int server_udp_count = 0;
static int server_tls_count = 0;

static struct clsrvconf *tcp_server_listen;
static struct clsrvconf *udp_server_listen;
static struct replyq *udp_server_replyq = NULL;
static int udp_server_sock = -1;
static pthread_mutex_t *ssl_locks;
static long *ssl_lock_count;
extern int optind;
extern char *optarg;

/* callbacks for making OpenSSL thread safe */
unsigned long ssl_thread_id() {
        return (unsigned long)pthread_self();
}

void ssl_locking_callback(int mode, int type, const char *file, int line) {
    if (mode & CRYPTO_LOCK) {
	pthread_mutex_lock(&ssl_locks[type]);
	ssl_lock_count[type]++;
    } else
	pthread_mutex_unlock(&ssl_locks[type]);
}

static int pem_passwd_cb(char *buf, int size, int rwflag, void *userdata) {
    int pwdlen = strlen(userdata);
    if (rwflag != 0 || pwdlen > size) /* not for decryption or too large */
	return 0;
    memcpy(buf, userdata, pwdlen);
    return pwdlen;
}

static int verify_cb(int ok, X509_STORE_CTX *ctx) {
  char buf[256];
  X509 *err_cert;
  int err, depth;

  err_cert = X509_STORE_CTX_get_current_cert(ctx);
  err = X509_STORE_CTX_get_error(ctx);
  depth = X509_STORE_CTX_get_error_depth(ctx);

  if (depth > MAX_CERT_DEPTH) {
      ok = 0;
      err = X509_V_ERR_CERT_CHAIN_TOO_LONG;
      X509_STORE_CTX_set_error(ctx, err);
  }

  if (!ok) {
      X509_NAME_oneline(X509_get_subject_name(err_cert), buf, 256);
      debug(DBG_WARN, "verify error: num=%d:%s:depth=%d:%s", err, X509_verify_cert_error_string(err), depth, buf);

      switch (err) {
      case X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT:
	  X509_NAME_oneline(X509_get_issuer_name(ctx->current_cert), buf, 256);
	  debug(DBG_WARN, "\tIssuer=%s", buf);
	  break;
      case X509_V_ERR_CERT_NOT_YET_VALID:
      case X509_V_ERR_ERROR_IN_CERT_NOT_BEFORE_FIELD:
	  debug(DBG_WARN, "\tCertificate not yet valid");
	  break;
      case X509_V_ERR_CERT_HAS_EXPIRED:
	  debug(DBG_WARN, "Certificate has expired");
	  break;
      case X509_V_ERR_ERROR_IN_CERT_NOT_AFTER_FIELD:
	  debug(DBG_WARN, "Certificate no longer valid (after notAfter)");
	  break;
      }
  }
#ifdef DEBUG  
  printf("certificate verify returns %d\n", ok);
#endif  
  return ok;
}

#ifdef DEBUG
void printauth(char *s, unsigned char *t) {
    int i;
    printf("%s:", s);
    for (i = 0; i < 16; i++)
	    printf("%02x ", t[i]);
    printf("\n");
}
#endif

int resolvepeer(struct clsrvconf *conf, int ai_flags) {
    struct addrinfo hints, *addrinfo;
    
    memset(&hints, 0, sizeof(hints));
    hints.ai_socktype = (conf->type == 'T' ? SOCK_STREAM : SOCK_DGRAM);
    hints.ai_family = AF_UNSPEC;
    hints.ai_flags = ai_flags;
    if (getaddrinfo(conf->host, conf->port, &hints, &addrinfo)) {
	debug(DBG_WARN, "resolvepeer: can't resolve %s port %s", conf->host, conf->port);
	return 0;
    }

    if (conf->addrinfo)
	freeaddrinfo(conf->addrinfo);
    conf->addrinfo = addrinfo;
    return 1;
}	  

int connecttoserver(struct addrinfo *addrinfo) {
    int s;
    struct addrinfo *res;

    s = -1;
    for (res = addrinfo; res; res = res->ai_next) {
        s = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
        if (s < 0) {
            debug(DBG_WARN, "connecttoserver: socket failed");
            continue;
        }
        if (connect(s, res->ai_addr, res->ai_addrlen) == 0)
            break;
        debug(DBG_WARN, "connecttoserver: connect failed");
        close(s);
        s = -1;
    }
    return s;
}	  

int bindtoaddr(struct addrinfo *addrinfo) {
    int s, on = 1;
    struct addrinfo *res;
    
    for (res = addrinfo; res; res = res->ai_next) {
        s = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
        if (s < 0) {
            debug(DBG_WARN, "bindtoaddr: socket failed");
            continue;
        }
	setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));
	if (!bind(s, res->ai_addr, res->ai_addrlen))
	    return s;
	debug(DBG_WARN, "bindtoaddr: bind failed");
        close(s);
    }
    return -1;
}	  

/* returns the peer with matching address, or NULL */
/* if conf argument is not NULL, we only check that one */
struct clsrvconf *find_peer(char type, struct sockaddr *addr, struct list *confs, struct clsrvconf *conf) {
    struct sockaddr_in6 *sa6 = NULL;
    struct in_addr *a4 = NULL;
    struct addrinfo *res;
    struct list_node *entry;
    
    if (addr->sa_family == AF_INET6) {
        sa6 = (struct sockaddr_in6 *)addr;
        if (IN6_IS_ADDR_V4MAPPED(&sa6->sin6_addr))
            a4 = (struct in_addr *)&sa6->sin6_addr.s6_addr[12];
    } else
	a4 = &((struct sockaddr_in *)addr)->sin_addr;

    if (conf) {
	if (conf->type == type)
	    for (res = conf->addrinfo; res; res = res->ai_next)
		if ((a4 && res->ai_family == AF_INET &&
		     !memcmp(a4, &((struct sockaddr_in *)res->ai_addr)->sin_addr, 4)) ||
		    (sa6 && res->ai_family == AF_INET6 &&
		     !memcmp(&sa6->sin6_addr, &((struct sockaddr_in6 *)res->ai_addr)->sin6_addr, 16)))
		    return conf;
	return NULL;
    }

    for (entry = list_first(confs); entry; entry = list_next(entry)) {	
	conf = (struct clsrvconf *)entry->data;
	if (conf->type == type)
	    for (res = conf->addrinfo; res; res = res->ai_next)
		if ((a4 && res->ai_family == AF_INET &&
		     !memcmp(a4, &((struct sockaddr_in *)res->ai_addr)->sin_addr, 4)) ||
		    (sa6 && res->ai_family == AF_INET6 &&
		     !memcmp(&sa6->sin6_addr, &((struct sockaddr_in6 *)res->ai_addr)->sin6_addr, 16)))
		    return conf;
    }    
    return NULL;
}

/* exactly one of client and server must be non-NULL */
/* should probably take peer list (client(s) or server(s)) as argument instead */
/* if *peer == NULL we return who we received from, else require it to be from peer */
/* return from in sa if not NULL */
unsigned char *radudpget(int s, struct client **client, struct server **server, struct sockaddr_storage *sa) {
    int cnt, len;
    unsigned char buf[65536], *rad;
    struct sockaddr_storage from;
    socklen_t fromlen = sizeof(from);
    struct clsrvconf *p;

    for (;;) {
	cnt = recvfrom(s, buf, sizeof(buf), 0, (struct sockaddr *)&from, &fromlen);
	if (cnt == -1) {
	    debug(DBG_WARN, "radudpget: recv failed");
	    continue;
	}
	debug(DBG_DBG, "radudpget: got %d bytes from %s", cnt, addr2string((struct sockaddr *)&from, fromlen));

	if (cnt < 20) {
	    debug(DBG_WARN, "radudpget: packet too small");
	    continue;
	}
    
	len = RADLEN(buf);
	if (len < 20) {
	    debug(DBG_WARN, "radudpget: length too small");
	    continue;
	}

	if (cnt < len) {
	    debug(DBG_WARN, "radudpget: packet smaller than length field in radius header");
	    continue;
	}
	if (cnt > len)
	    debug(DBG_DBG, "radudpget: packet was padded with %d bytes", cnt - len);

	if (client)
	    if (*client)
		p = find_peer('U', (struct sockaddr *)&from, NULL, (*client)->conf);
	    else
		p = find_peer('U', (struct sockaddr *)&from, clconfs, NULL);
	else
	    if (*server)
		p = find_peer('U', (struct sockaddr *)&from, NULL, (*server)->conf);
	    else
		p = find_peer('U', (struct sockaddr *)&from, srvconfs, NULL);

	if (!p) {
	    debug(DBG_WARN, "radudpget: got packet from wrong or unknown UDP peer, ignoring");
	    continue;
	}

	rad = malloc(len);
	if (rad)
	    break;
	debug(DBG_ERR, "radudpget: malloc failed");
    }
    memcpy(rad, buf, len);
    if (client && !*client)
	*client = p->clients;
    else if (server && !*server)
	*server = p->servers;
    if (sa)
	*sa = from;
    return rad;
}

int tlsverifycert(SSL *ssl, struct clsrvconf *conf) {
    int l, loc;
    X509 *cert;
    X509_NAME *nm;
    X509_NAME_ENTRY *e;
    unsigned char *v;
    unsigned long error;

    if (SSL_get_verify_result(ssl) != X509_V_OK) {
	debug(DBG_ERR, "tlsverifycert: basic validation failed");
	while ((error = ERR_get_error()))
	    debug(DBG_ERR, "tlsverifycert: TLS: %s", ERR_error_string(error, NULL));
	return 0;
    }

    cert = SSL_get_peer_certificate(ssl);
    if (!cert) {
	debug(DBG_ERR, "tlsverifycert: failed to obtain certificate");
	return 0;
    }
    nm = X509_get_subject_name(cert);
    loc = -1;
    for (;;) {
	loc = X509_NAME_get_index_by_NID(nm, NID_commonName, loc);
	if (loc == -1)
	    break;
	e = X509_NAME_get_entry(nm, loc);
	l = ASN1_STRING_to_UTF8(&v, X509_NAME_ENTRY_get_data(e));
	if (l < 0)
	    continue;
#ifdef DEBUG
	{
	    int i;
	    printf("cn: ");
	    for (i = 0; i < l; i++)
		printf("%c", v[i]);
	    printf("\n");
	}
#endif	
	if (l == strlen(conf->host) && !strncasecmp(conf->host, (char *)v, l)) {
	    debug(DBG_DBG, "tlsverifycert: Found cn matching host %s, All OK", conf->host);
	    return 1;
	}
	debug(DBG_ERR, "tlsverifycert: cn not matching host %s", conf->host);
    }
    X509_free(cert);
    return 0;
}

void tlsconnect(struct server *server, struct timeval *when, char *text) {
    struct timeval now;
    time_t elapsed;

    debug(DBG_DBG, "tlsconnect called from %s", text);
    pthread_mutex_lock(&server->lock);
    if (when && memcmp(&server->lastconnecttry, when, sizeof(struct timeval))) {
	/* already reconnected, nothing to do */
	debug(DBG_DBG, "tlsconnect(%s): seems already reconnected", text);
	pthread_mutex_unlock(&server->lock);
	return;
    }

    debug(DBG_DBG, "tlsconnect %s", text);

    for (;;) {
	gettimeofday(&now, NULL);
	elapsed = now.tv_sec - server->lastconnecttry.tv_sec;
	if (server->connectionok) {
	    server->connectionok = 0;
	    sleep(10);
	} else if (elapsed < 5)
	    sleep(10);
	else if (elapsed < 300) {
	    debug(DBG_INFO, "tlsconnect: sleeping %lds", elapsed);
	    sleep(elapsed);
	} else if (elapsed < 100000) {
	    debug(DBG_INFO, "tlsconnect: sleeping %ds", 600);
	    sleep(600);
	} else
	    server->lastconnecttry.tv_sec = now.tv_sec;  /* no sleep at startup */
	debug(DBG_WARN, "tlsconnect: trying to open TLS connection to %s port %s", server->conf->host, server->conf->port);
	if (server->sock >= 0)
	    close(server->sock);
	if ((server->sock = connecttoserver(server->conf->addrinfo)) < 0) {
	    debug(DBG_ERR, "tlsconnect: connecttoserver failed");
	    continue;
	}
	
	SSL_free(server->ssl);
	server->ssl = SSL_new(server->conf->ssl_ctx);
	SSL_set_fd(server->ssl, server->sock);
	if (SSL_connect(server->ssl) > 0 && tlsverifycert(server->ssl, server->conf))
	    break;
    }
    debug(DBG_WARN, "tlsconnect: TLS connection to %s port %s up", server->conf->host, server->conf->port);
    gettimeofday(&server->lastconnecttry, NULL);
    pthread_mutex_unlock(&server->lock);
}

unsigned char *radtlsget(SSL *ssl) {
    int cnt, total, len;
    unsigned char buf[4], *rad;

    for (;;) {
	for (total = 0; total < 4; total += cnt) {
	    cnt = SSL_read(ssl, buf + total, 4 - total);
	    if (cnt <= 0) {
		debug(DBG_ERR, "radtlsget: connection lost");
		if (SSL_get_error(ssl, cnt) == SSL_ERROR_ZERO_RETURN) {
		    /* remote end sent close_notify, send one back */
		    SSL_shutdown(ssl);
		}
		return NULL;
	    }
	}

	len = RADLEN(buf);
	rad = malloc(len);
	if (!rad) {
	    debug(DBG_ERR, "radtlsget: malloc failed");
	    continue;
	}
	memcpy(rad, buf, 4);

	for (; total < len; total += cnt) {
	    cnt = SSL_read(ssl, rad + total, len - total);
	    if (cnt <= 0) {
		debug(DBG_ERR, "radtlsget: connection lost");
		if (SSL_get_error(ssl, cnt) == SSL_ERROR_ZERO_RETURN) {
		    /* remote end sent close_notify, send one back */
		    SSL_shutdown(ssl);
		}
		free(rad);
		return NULL;
	    }
	}
    
	if (total >= 20)
	    break;
	
	free(rad);
	debug(DBG_WARN, "radtlsget: packet smaller than minimum radius size");
    }
    
    debug(DBG_DBG, "radtlsget: got %d bytes", total);
    return rad;
}

int clientradput(struct server *server, unsigned char *rad) {
    int cnt;
    size_t len;
    unsigned long error;
    struct timeval lastconnecttry;
    
    len = RADLEN(rad);
    if (server->conf->type == 'U') {
	if (send(server->sock, rad, len, 0) >= 0) {
	    debug(DBG_DBG, "clienradput: sent UDP of length %d to %s port %s", len, server->conf->host, server->conf->port);
	    return 1;
	}
	debug(DBG_WARN, "clientradput: send failed");
	return 0;
    }

    lastconnecttry = server->lastconnecttry;
    while ((cnt = SSL_write(server->ssl, rad, len)) <= 0) {
	while ((error = ERR_get_error()))
	    debug(DBG_ERR, "clientradput: TLS: %s", ERR_error_string(error, NULL));
	tlsconnect(server, &lastconnecttry, "clientradput");
	lastconnecttry = server->lastconnecttry;
    }

    server->connectionok = 1;
    debug(DBG_DBG, "clientradput: Sent %d bytes, Radius packet of length %d to TLS peer %s",
	   cnt, len, server->conf->host);
    return 1;
}

int radsign(unsigned char *rad, unsigned char *sec) {
    static pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
    static unsigned char first = 1;
    static EVP_MD_CTX mdctx;
    unsigned int md_len;
    int result;
    
    pthread_mutex_lock(&lock);
    if (first) {
	EVP_MD_CTX_init(&mdctx);
	first = 0;
    }

    result = (EVP_DigestInit_ex(&mdctx, EVP_md5(), NULL) &&
	EVP_DigestUpdate(&mdctx, rad, RADLEN(rad)) &&
	EVP_DigestUpdate(&mdctx, sec, strlen((char *)sec)) &&
	EVP_DigestFinal_ex(&mdctx, rad + 4, &md_len) &&
	md_len == 16);
    pthread_mutex_unlock(&lock);
    return result;
}

int validauth(unsigned char *rad, unsigned char *reqauth, unsigned char *sec) {
    static pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
    static unsigned char first = 1;
    static EVP_MD_CTX mdctx;
    unsigned char hash[EVP_MAX_MD_SIZE];
    unsigned int len;
    int result;
    
    pthread_mutex_lock(&lock);
    if (first) {
	EVP_MD_CTX_init(&mdctx);
	first = 0;
    }

    len = RADLEN(rad);
    
    result = (EVP_DigestInit_ex(&mdctx, EVP_md5(), NULL) &&
	      EVP_DigestUpdate(&mdctx, rad, 4) &&
	      EVP_DigestUpdate(&mdctx, reqauth, 16) &&
	      (len <= 20 || EVP_DigestUpdate(&mdctx, rad + 20, len - 20)) &&
	      EVP_DigestUpdate(&mdctx, sec, strlen((char *)sec)) &&
	      EVP_DigestFinal_ex(&mdctx, hash, &len) &&
	      len == 16 &&
	      !memcmp(hash, rad + 4, 16));
    pthread_mutex_unlock(&lock);
    return result;
}
	      
int checkmessageauth(unsigned char *rad, uint8_t *authattr, char *secret) {
    static pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
    static unsigned char first = 1;
    static HMAC_CTX hmacctx;
    unsigned int md_len;
    uint8_t auth[16], hash[EVP_MAX_MD_SIZE];
    
    pthread_mutex_lock(&lock);
    if (first) {
	HMAC_CTX_init(&hmacctx);
	first = 0;
    }

    memcpy(auth, authattr, 16);
    memset(authattr, 0, 16);
    md_len = 0;
    HMAC_Init_ex(&hmacctx, secret, strlen(secret), EVP_md5(), NULL);
    HMAC_Update(&hmacctx, rad, RADLEN(rad));
    HMAC_Final(&hmacctx, hash, &md_len);
    memcpy(authattr, auth, 16);
    if (md_len != 16) {
	debug(DBG_WARN, "message auth computation failed");
	pthread_mutex_unlock(&lock);
	return 0;
    }

    if (memcmp(auth, hash, 16)) {
	debug(DBG_WARN, "message authenticator, wrong value");
	pthread_mutex_unlock(&lock);
	return 0;
    }	
	
    pthread_mutex_unlock(&lock);
    return 1;
}

int createmessageauth(unsigned char *rad, unsigned char *authattrval, char *secret) {
    static pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
    static unsigned char first = 1;
    static HMAC_CTX hmacctx;
    unsigned int md_len;

    if (!authattrval)
	return 1;
    
    pthread_mutex_lock(&lock);
    if (first) {
	HMAC_CTX_init(&hmacctx);
	first = 0;
    }

    memset(authattrval, 0, 16);
    md_len = 0;
    HMAC_Init_ex(&hmacctx, secret, strlen(secret), EVP_md5(), NULL);
    HMAC_Update(&hmacctx, rad, RADLEN(rad));
    HMAC_Final(&hmacctx, authattrval, &md_len);
    if (md_len != 16) {
	debug(DBG_WARN, "message auth computation failed");
	pthread_mutex_unlock(&lock);
	return 0;
    }

    pthread_mutex_unlock(&lock);
    return 1;
}

unsigned char *attrget(unsigned char *attrs, int length, uint8_t type) {
    while (length > 1) {
	if (ATTRTYPE(attrs) == type)
	    return attrs;
	length -= ATTRLEN(attrs);
	attrs += ATTRLEN(attrs);
    }
    return NULL;
}

void sendrq(struct server *to, struct request *rq) {
    int i;
    uint8_t *attr;

    pthread_mutex_lock(&to->newrq_mutex);
    /* might simplify if only try nextid, might be ok */
    for (i = to->nextid; i < MAX_REQUESTS; i++)
	if (!to->requests[i].buf)
	    break;
    if (i == MAX_REQUESTS) {
	for (i = 0; i < to->nextid; i++)
	    if (!to->requests[i].buf)
		break;
	if (i == to->nextid) {
	    debug(DBG_WARN, "No room in queue, dropping request");
	    free(rq->buf);
	    pthread_mutex_unlock(&to->newrq_mutex);
	    return;
	}
    }
    
    rq->buf[1] = (char)i;

    attr = attrget(rq->buf + 20, RADLEN(rq->buf) - 20, RAD_Attr_Message_Authenticator);
    if (attr && !createmessageauth(rq->buf, ATTRVAL(attr), to->conf->secret)) {
	free(rq->buf);
	pthread_mutex_unlock(&to->newrq_mutex);
	return;
    }

    debug(DBG_DBG, "sendrq: inserting packet with id %d in queue for %s", i, to->conf->host);
    to->requests[i] = *rq;
    to->nextid = i + 1;

    if (!to->newrq) {
	to->newrq = 1;
	debug(DBG_DBG, "signalling client writer");
	pthread_cond_signal(&to->newrq_cond);
    }
    pthread_mutex_unlock(&to->newrq_mutex);
}

void sendreply(struct client *to, unsigned char *buf, struct sockaddr_storage *tosa) {
    struct replyq *replyq = to->replyq;
    
    if (!radsign(buf, (unsigned char *)to->conf->secret)) {
	free(buf);
	debug(DBG_WARN, "sendreply: failed to sign message");
	return;
    }
	
    pthread_mutex_lock(&replyq->count_mutex);
    if (replyq->count == replyq->size) {
	debug(DBG_WARN, "No room in queue, dropping request");
	pthread_mutex_unlock(&replyq->count_mutex);
	free(buf);
	return;
    }

    replyq->replies[replyq->count].buf = buf;
    if (tosa)
	replyq->replies[replyq->count].tosa = *tosa;
    replyq->count++;

    if (replyq->count == 1) {
	debug(DBG_DBG, "signalling server writer");
	pthread_cond_signal(&replyq->count_cond);
    }
    pthread_mutex_unlock(&replyq->count_mutex);
}

int pwdencrypt(uint8_t *in, uint8_t len, char *shared, uint8_t sharedlen, uint8_t *auth) {
    static pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
    static unsigned char first = 1;
    static EVP_MD_CTX mdctx;
    unsigned char hash[EVP_MAX_MD_SIZE], *input;
    unsigned int md_len;
    uint8_t i, offset = 0, out[128];
    
    pthread_mutex_lock(&lock);
    if (first) {
	EVP_MD_CTX_init(&mdctx);
	first = 0;
    }

    input = auth;
    for (;;) {
	if (!EVP_DigestInit_ex(&mdctx, EVP_md5(), NULL) ||
	    !EVP_DigestUpdate(&mdctx, (uint8_t *)shared, sharedlen) ||
	    !EVP_DigestUpdate(&mdctx, input, 16) ||
	    !EVP_DigestFinal_ex(&mdctx, hash, &md_len) ||
	    md_len != 16) {
	    pthread_mutex_unlock(&lock);
	    return 0;
	}
	for (i = 0; i < 16; i++)
	    out[offset + i] = hash[i] ^ in[offset + i];
	input = out + offset - 16;
	offset += 16;
	if (offset == len)
	    break;
    }
    memcpy(in, out, len);
    pthread_mutex_unlock(&lock);
    return 1;
}

int pwddecrypt(uint8_t *in, uint8_t len, char *shared, uint8_t sharedlen, uint8_t *auth) {
    static pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
    static unsigned char first = 1;
    static EVP_MD_CTX mdctx;
    unsigned char hash[EVP_MAX_MD_SIZE], *input;
    unsigned int md_len;
    uint8_t i, offset = 0, out[128];
    
    pthread_mutex_lock(&lock);
    if (first) {
	EVP_MD_CTX_init(&mdctx);
	first = 0;
    }

    input = auth;
    for (;;) {
	if (!EVP_DigestInit_ex(&mdctx, EVP_md5(), NULL) ||
	    !EVP_DigestUpdate(&mdctx, (uint8_t *)shared, sharedlen) ||
	    !EVP_DigestUpdate(&mdctx, input, 16) ||
	    !EVP_DigestFinal_ex(&mdctx, hash, &md_len) ||
	    md_len != 16) {
	    pthread_mutex_unlock(&lock);
	    return 0;
	}
	for (i = 0; i < 16; i++)
	    out[offset + i] = hash[i] ^ in[offset + i];
	input = in + offset;
	offset += 16;
	if (offset == len)
	    break;
    }
    memcpy(in, out, len);
    pthread_mutex_unlock(&lock);
    return 1;
}

int msmppencrypt(uint8_t *text, uint8_t len, uint8_t *shared, uint8_t sharedlen, uint8_t *auth, uint8_t *salt) {
    static pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
    static unsigned char first = 1;
    static EVP_MD_CTX mdctx;
    unsigned char hash[EVP_MAX_MD_SIZE];
    unsigned int md_len;
    uint8_t i, offset;
    
    pthread_mutex_lock(&lock);
    if (first) {
	EVP_MD_CTX_init(&mdctx);
	first = 0;
    }

#if 0    
    printf("msppencrypt auth in: ");
    for (i = 0; i < 16; i++)
	printf("%02x ", auth[i]);
    printf("\n");
    
    printf("msppencrypt salt in: ");
    for (i = 0; i < 2; i++)
	printf("%02x ", salt[i]);
    printf("\n");
    
    printf("msppencrypt in: ");
    for (i = 0; i < len; i++)
	printf("%02x ", text[i]);
    printf("\n");
#endif
    
    if (!EVP_DigestInit_ex(&mdctx, EVP_md5(), NULL) ||
	!EVP_DigestUpdate(&mdctx, shared, sharedlen) ||
	!EVP_DigestUpdate(&mdctx, auth, 16) ||
	!EVP_DigestUpdate(&mdctx, salt, 2) ||
	!EVP_DigestFinal_ex(&mdctx, hash, &md_len)) {
	pthread_mutex_unlock(&lock);
	return 0;
    }

#if 0    
    printf("msppencrypt hash: ");
    for (i = 0; i < 16; i++)
	printf("%02x ", hash[i]);
    printf("\n");
#endif
    
    for (i = 0; i < 16; i++)
	text[i] ^= hash[i];
    
    for (offset = 16; offset < len; offset += 16) {
#if 0	
	printf("text + offset - 16 c(%d): ", offset / 16);
	for (i = 0; i < 16; i++)
	    printf("%02x ", (text + offset - 16)[i]);
	printf("\n");
#endif
	if (!EVP_DigestInit_ex(&mdctx, EVP_md5(), NULL) ||
	    !EVP_DigestUpdate(&mdctx, shared, sharedlen) ||
	    !EVP_DigestUpdate(&mdctx, text + offset - 16, 16) ||
	    !EVP_DigestFinal_ex(&mdctx, hash, &md_len) ||
	    md_len != 16) {
	    pthread_mutex_unlock(&lock);
	    return 0;
	}
#if 0	
	printf("msppencrypt hash: ");
	for (i = 0; i < 16; i++)
	    printf("%02x ", hash[i]);
	printf("\n");
#endif    
	
	for (i = 0; i < 16; i++)
	    text[offset + i] ^= hash[i];
    }
    
#if 0
    printf("msppencrypt out: ");
    for (i = 0; i < len; i++)
	printf("%02x ", text[i]);
    printf("\n");
#endif

    pthread_mutex_unlock(&lock);
    return 1;
}

int msmppdecrypt(uint8_t *text, uint8_t len, uint8_t *shared, uint8_t sharedlen, uint8_t *auth, uint8_t *salt) {
    static pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
    static unsigned char first = 1;
    static EVP_MD_CTX mdctx;
    unsigned char hash[EVP_MAX_MD_SIZE];
    unsigned int md_len;
    uint8_t i, offset;
    char plain[255];
    
    pthread_mutex_lock(&lock);
    if (first) {
	EVP_MD_CTX_init(&mdctx);
	first = 0;
    }

#if 0    
    printf("msppdecrypt auth in: ");
    for (i = 0; i < 16; i++)
	printf("%02x ", auth[i]);
    printf("\n");
    
    printf("msppedecrypt salt in: ");
    for (i = 0; i < 2; i++)
	printf("%02x ", salt[i]);
    printf("\n");
    
    printf("msppedecrypt in: ");
    for (i = 0; i < len; i++)
	printf("%02x ", text[i]);
    printf("\n");
#endif
    
    if (!EVP_DigestInit_ex(&mdctx, EVP_md5(), NULL) ||
	!EVP_DigestUpdate(&mdctx, shared, sharedlen) ||
	!EVP_DigestUpdate(&mdctx, auth, 16) ||
	!EVP_DigestUpdate(&mdctx, salt, 2) ||
	!EVP_DigestFinal_ex(&mdctx, hash, &md_len)) {
	pthread_mutex_unlock(&lock);
	return 0;
    }

#if 0    
    printf("msppedecrypt hash: ");
    for (i = 0; i < 16; i++)
	printf("%02x ", hash[i]);
    printf("\n");
#endif
    
    for (i = 0; i < 16; i++)
	plain[i] = text[i] ^ hash[i];
    
    for (offset = 16; offset < len; offset += 16) {
#if 0 	
	printf("text + offset - 16 c(%d): ", offset / 16);
	for (i = 0; i < 16; i++)
	    printf("%02x ", (text + offset - 16)[i]);
	printf("\n");
#endif
	if (!EVP_DigestInit_ex(&mdctx, EVP_md5(), NULL) ||
	    !EVP_DigestUpdate(&mdctx, shared, sharedlen) ||
	    !EVP_DigestUpdate(&mdctx, text + offset - 16, 16) ||
	    !EVP_DigestFinal_ex(&mdctx, hash, &md_len) ||
	    md_len != 16) {
	    pthread_mutex_unlock(&lock);
	    return 0;
	}
#if 0	
    printf("msppedecrypt hash: ");
    for (i = 0; i < 16; i++)
	printf("%02x ", hash[i]);
    printf("\n");
#endif    

    for (i = 0; i < 16; i++)
	plain[offset + i] = text[offset + i] ^ hash[i];
    }

    memcpy(text, plain, len);
#if 0
    printf("msppedecrypt out: ");
    for (i = 0; i < len; i++)
	printf("%02x ", text[i]);
    printf("\n");
#endif

    pthread_mutex_unlock(&lock);
    return 1;
}

struct realm *id2realm(char *id, uint8_t len) {
    struct list_node *entry;
    struct realm *realm;
    
    for (entry = list_first(realms); entry; entry = list_next(entry)) {
	realm = (struct realm *)entry->data;
	if (!regexec(&realm->regex, id, 0, NULL, 0)) {
	    debug(DBG_DBG, "found matching realm: %s", realm->name);
	    return realm;
	}
    }
    return NULL;
}

int rqinqueue(struct server *to, struct client *from, uint8_t id) {
    int i;
    
    pthread_mutex_lock(&to->newrq_mutex);
    for (i = 0; i < MAX_REQUESTS; i++)
	if (to->requests[i].buf && to->requests[i].origid == id && to->requests[i].from == from)
	    break;
    pthread_mutex_unlock(&to->newrq_mutex);
    
    return i < MAX_REQUESTS;
}

int attrvalidate(unsigned char *attrs, int length) {
    while (length > 1) {
	if (ATTRLEN(attrs) < 2) {
	    debug(DBG_WARN, "attrvalidate: invalid attribute length %d", ATTRLEN(attrs));
	    return 0;
	}
	length -= ATTRLEN(attrs);
	if (length < 0) {
	    debug(DBG_WARN, "attrvalidate: attribute length %d exceeds packet length", ATTRLEN(attrs));
	    return 0;
	}
	attrs += ATTRLEN(attrs);
    }
    if (length)
	debug(DBG_WARN, "attrvalidate: malformed packet? remaining byte after last attribute");
    return 1;
}

int pwdrecrypt(uint8_t *pwd, uint8_t len, char *oldsecret, char *newsecret, uint8_t *oldauth, uint8_t *newauth) {
#ifdef DEBUG    
    int i;
#endif    
    if (len < 16 || len > 128 || len % 16) {
	debug(DBG_WARN, "pwdrecrypt: invalid password length");
	return 0;
    }
	
    if (!pwddecrypt(pwd, len, oldsecret, strlen(oldsecret), oldauth)) {
	debug(DBG_WARN, "pwdrecrypt: cannot decrypt password");
	return 0;
    }
#ifdef DEBUG
    printf("pwdrecrypt: password: ");
    for (i = 0; i < len; i++)
	printf("%02x ", pwd[i]);
    printf("\n");
#endif	
    if (!pwdencrypt(pwd, len, newsecret, strlen(newsecret), newauth)) {
	debug(DBG_WARN, "pwdrecrypt: cannot encrypt password");
	return 0;
    }
    return 1;
}

int msmpprecrypt(uint8_t *msmpp, uint8_t len, char *oldsecret, char *newsecret, unsigned char *oldauth, char *newauth) {
    if (len < 18)
	return 0;
    if (!msmppdecrypt(msmpp + 2, len - 2, (unsigned char *)oldsecret, strlen(oldsecret), oldauth, msmpp)) {
	debug(DBG_WARN, "msmpprecrypt: failed to decrypt msppe key");
	return 0;
    }
    if (!msmppencrypt(msmpp + 2, len - 2, (unsigned char *)newsecret, strlen(newsecret), (unsigned char *)newauth, msmpp)) {
	debug(DBG_WARN, "msmpprecrypt: failed to encrypt msppe key");
	return 0;
    }
    return 1;
}

int msmppe(unsigned char *attrs, int length, uint8_t type, char *attrtxt, struct request *rq,
	   char *oldsecret, char *newsecret) {
    unsigned char *attr;
    
    for (attr = attrs; (attr = attrget(attr, length - (attr - attrs), type)); attr += ATTRLEN(attr)) {
	debug(DBG_DBG, "msmppe: Got %s", attrtxt);
	if (!msmpprecrypt(ATTRVAL(attr), ATTRVALLEN(attr), oldsecret, newsecret, rq->buf + 4, rq->origauth))
	    return 0;
    }
    return 1;
}

void respondstatusserver(struct request *rq) {
    unsigned char *resp;

    resp = malloc(20);
    if (!resp) {
	debug(DBG_ERR, "respondstatusserver: malloc failed");
	return;
    }
    memcpy(resp, rq->buf, 20);
    resp[0] = RAD_Access_Accept;
    resp[2] = 0;
    resp[3] = 20;
    debug(DBG_DBG, "respondstatusserver: responding to %s", rq->from->conf->host);
    sendreply(rq->from, resp, rq->from->conf->type == 'U' ? &rq->fromsa : NULL);
}

void respondreject(struct request *rq, char *message) {
    unsigned char *resp;
    int len = 20;

    if (message)
	len += 2 + strlen(message);
    
    resp = malloc(len);
    if (!resp) {
	debug(DBG_ERR, "respondreject: malloc failed");
	return;
    }
    memcpy(resp, rq->buf, 20);
    resp[0] = RAD_Access_Reject;
    *(uint16_t *)(resp + 2) = htons(len);
    if (message) {
	resp[20] = RAD_Attr_Reply_Message;
	resp[21] = len - 20;
	memcpy(resp + 22, message, len - 22);
    }
    sendreply(rq->from, resp, rq->from->conf->type == 'U' ? &rq->fromsa : NULL);
}

void radsrv(struct request *rq) {
    uint8_t code, id, *auth, *attrs, *attr;
    uint16_t len;
    struct server *to = NULL;
    char username[256];
    unsigned char *buf, newauth[16];
    struct realm *realm = NULL;
    
    buf = rq->buf;
    code = *(uint8_t *)buf;
    id = *(uint8_t *)(buf + 1);
    len = RADLEN(buf);
    auth = (uint8_t *)(buf + 4);

    debug(DBG_DBG, "radsrv: code %d, id %d, length %d", code, id, len);
    
    if (code != RAD_Access_Request && code != RAD_Status_Server) {
	debug(DBG_INFO, "radsrv: server currently accepts only access-requests and status-server, ignoring");
	free(buf);
	return;
    }

    len -= 20;
    attrs = buf + 20;

    if (!attrvalidate(attrs, len)) {
	debug(DBG_WARN, "radsrv: attribute validation failed, ignoring packet");
	free(buf);
	return;
    }

    if (code == RAD_Access_Request) {
	attr = attrget(attrs, len, RAD_Attr_User_Name);
	if (!attr) {
	    debug(DBG_WARN, "radsrv: ignoring request, no username attribute");
	    free(buf);
	    return;
	}
	memcpy(username, ATTRVAL(attr), ATTRVALLEN(attr));
	username[ATTRVALLEN(attr)] = '\0';
	debug(DBG_DBG, "Access Request with username: %s", username);

	realm = id2realm(username, strlen(username));
	if (!realm) {
	    debug(DBG_INFO, "radsrv: ignoring request, don't know where to send it");
	    free(buf);
	    return;
	}
	to = realm->srvconf->servers;

	if (to && rqinqueue(to, rq->from, id)) {
	    debug(DBG_INFO, "radsrv: already got request from host %s with id %d, ignoring", rq->from->conf->host, id);
	    free(buf);
	    return;
	}
    }
    
    attr = attrget(attrs, len, RAD_Attr_Message_Authenticator);
    if (attr && (ATTRVALLEN(attr) != 16 || !checkmessageauth(buf, ATTRVAL(attr), rq->from->conf->secret))) {
	debug(DBG_WARN, "radsrv: message authentication failed");
	free(buf);
	return;
    }
    
    if (code == RAD_Status_Server) {
	respondstatusserver(rq);
	return;
    }

    if (!to) {
	debug(DBG_INFO, "radsrv: sending reject to %s for %s", rq->from->conf->host, username);
	respondreject(rq, realm->message);
	return;
    }
    
    if (!RAND_bytes(newauth, 16)) {
	debug(DBG_WARN, "radsrv: failed to generate random auth");
	free(buf);
	return;
    }

#ifdef DEBUG    
    printauth("auth", auth);
#endif

    attr = attrget(attrs, len, RAD_Attr_User_Password);
    if (attr) {
	debug(DBG_DBG, "radsrv: found userpwdattr with value length %d", ATTRVALLEN(attr));
	if (!pwdrecrypt(ATTRVAL(attr), ATTRVALLEN(attr), rq->from->conf->secret, to->conf->secret, auth, newauth)) {
	    free(buf);
	    return;
	}
    }
    
    attr = attrget(attrs, len, RAD_Attr_Tunnel_Password);
    if (attr) {
	debug(DBG_DBG, "radsrv: found tunnelpwdattr with value length %d", ATTRVALLEN(attr));
	if (!pwdrecrypt(ATTRVAL(attr), ATTRVALLEN(attr), rq->from->conf->secret, to->conf->secret, auth, newauth)) {
	    free(buf);
	    return;
	}
    }

    rq->origid = id;
    memcpy(rq->origauth, auth, 16);
    memcpy(auth, newauth, 16);
    sendrq(to, rq);
}

void *clientrd(void *arg) {
    struct server *server = (struct server *)arg;
    struct client *from;
    int i, len, sublen;
    unsigned char *buf, *messageauth, *subattrs, *attrs, *attr;
    struct sockaddr_storage fromsa;
    struct timeval lastconnecttry;
    char tmp[256];