radsecproxy.c

/*
 * Copyright (C) 2006 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.
 */

/* BUGS:
 * peers can not yet be specified with literal IPv6 addresses due to port syntax
 */

/* TODO:
 * make our server ignore client retrans and do its own instead?
 * accounting
 * radius keep alives (server status)
 * tls certificate validation, see below urls
 * clean tls shutdown, see http://www.linuxjournal.com/article/4822
 *     and http://www.linuxjournal.com/article/5487
 *     SSL_shutdown() and shutdown()
 *     If shutdown() we may not need REUSEADDR
 * when tls client goes away, ensure that all related threads and state
 *          are removed
 * setsockopt(keepalive...), check if openssl has some keepalive feature
*/

/* 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 <netdb.h>
#include <unistd.h>
#include <sys/time.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 "radsecproxy.h"

static struct options options;
static struct client clients[MAX_PEERS];
static struct server servers[MAX_PEERS];

static int client_count = 0;
static int server_count = 0;

static struct replyq udp_server_replyq;
static int udp_server_sock = -1;
static pthread_mutex_t *ssl_locks;
static long *ssl_lock_count;
static SSL_CTX *ssl_ctx = NULL;
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]);
}

void ssl_init() {
    int i;
    unsigned long error;
    
    if (!options.tlscertificatefile || !options.tlscertificatekeyfile) {
	printf("TLSCertificateFile and TLSCertificateKeyFile must be specified for TLS\n");
	exit(1);
    }

    ssl_locks = malloc(CRYPTO_num_locks() * sizeof(pthread_mutex_t));
    ssl_lock_count = OPENSSL_malloc(CRYPTO_num_locks() * sizeof(long));
    for (i = 0; i < CRYPTO_num_locks(); i++) {
	ssl_lock_count[i] = 0;
	pthread_mutex_init(&ssl_locks[i], NULL);
    }
    CRYPTO_set_id_callback(ssl_thread_id);
    CRYPTO_set_locking_callback(ssl_locking_callback);

    SSL_load_error_strings();
    SSL_library_init();

    while (!RAND_status()) {
	time_t t = time(NULL);
	pid_t pid = getpid();
	RAND_seed((unsigned char *)&t, sizeof(time_t));
        RAND_seed((unsigned char *)&pid, sizeof(pid));
    }

    ssl_ctx = SSL_CTX_new(TLSv1_method());
    if (!ssl_ctx) {
	printf("failed to initialise ssl");
	exit(1);
    }

    if (!SSL_CTX_use_certificate_file(ssl_ctx, options.tlscertificatefile, SSL_FILETYPE_PEM)) {
        while ((error = ERR_get_error()))
            err("SSL: %s", ERR_error_string(error, NULL));
        errx("Failed to load certificate");
    }
    if (!SSL_CTX_use_PrivateKey_file(ssl_ctx, options.tlscertificatekeyfile, SSL_FILETYPE_PEM)) {
	while ((error = ERR_get_error()))
	    err("SSL: %s", ERR_error_string(error, NULL));
	errx("Failed to load private key");
    }
}    

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

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

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

int connecttoserver(struct addrinfo *addrinfo) {
    int s;
    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) {
            err("connecttoserver: socket failed");
            continue;
        }
        if (connect(s, res->ai_addr, res->ai_addrlen) == 0)
            break;
        err("connecttoserver: connect failed");
        close(s);
        s = -1;
    }
    return s;
}	  

/* returns the client with matching address, or NULL */
/* if client argument is not NULL, we only check that one client */
struct client *find_client(char type, struct sockaddr *addr, struct client *client) {
    struct sockaddr_in6 *sa6;
    struct in_addr *a4 = NULL;
    struct client *c;
    int i;
    struct addrinfo *res;

    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;

    c = (client ? client : clients);
    for (i = 0; i < client_count; i++) {
	if (c->peer.type == type)
	    for (res = c->peer.addrinfo; res; res = res->ai_next)
		if ((a4 && res->ai_family == AF_INET &&
		     !memcmp(a4, &((struct sockaddr_in *)res->ai_addr)->sin_addr, 4)) ||
		    (res->ai_family == AF_INET6 &&
		     !memcmp(&sa6->sin6_addr, &((struct sockaddr_in6 *)res->ai_addr)->sin6_addr, 16)))
		    return c;
	if (client)
	    break;
	c++;
    }
    return NULL;
}

/* returns the server with matching address, or NULL */
/* if server argument is not NULL, we only check that one server */
struct server *find_server(char type, struct sockaddr *addr, struct server *server) {
    struct sockaddr_in6 *sa6;
    struct in_addr *a4 = NULL;
    struct server *s;
    int i;
    struct addrinfo *res;

    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;

    s = (server ? server : servers);
    for (i = 0; i < server_count; i++) {
	if (s->peer.type == type)
	    for (res = s->peer.addrinfo; res; res = res->ai_next)
		if ((a4 && res->ai_family == AF_INET &&
		     !memcmp(a4, &((struct sockaddr_in *)res->ai_addr)->sin_addr, 4)) ||
		    (res->ai_family == AF_INET6 &&
		     !memcmp(&sa6->sin6_addr, &((struct sockaddr_in6 *)res->ai_addr)->sin6_addr, 16)))
		    return s;
	if (server)
	    break;
	s++;
    }
    return NULL;
}

/* exactly one of client and server must be non-NULL */
/* 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;
    void *f;
    unsigned char buf[65536], *rad;
    struct sockaddr_storage from;
    socklen_t fromlen = sizeof(from);

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

	if (cnt < 20) {
	    printf("radudpget: packet too small\n");
	    continue;
	}
    
	len = RADLEN(buf);

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

	f = (client
	     ? (void *)find_client('U', (struct sockaddr *)&from, *client)
	     : (void *)find_server('U', (struct sockaddr *)&from, *server));
	if (!f) {
	    printf("radudpget: got packet from wrong or unknown UDP peer, ignoring\n");
	    continue;
	}

	rad = malloc(len);
	if (rad)
	    break;
	err("radudpget: malloc failed");
    }
    memcpy(rad, buf, len);
    if (client)
	*client = (struct client *)f; /* only need this if *client == NULL, but if not NULL *client == f here */
    else
	*server = (struct server *)f; /* only need this if *server == NULL, but if not NULL *server == f here */
    if (sa)
	*sa = from;
    return rad;
}

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

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

    printf("tlsconnect %s\n", 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 < 600)
	    sleep(elapsed * 2);
	else if (elapsed < 10000)
		sleep(900);
	else
	    server->lastconnecttry.tv_sec = now.tv_sec;  // no sleep at startup
	printf("tlsconnect: trying to open TLS connection to %s port %s\n", server->peer.host, server->peer.port);
	if (server->sock >= 0)
	    close(server->sock);
	if ((server->sock = connecttoserver(server->peer.addrinfo)) < 0)
	    continue;
	SSL_free(server->peer.ssl);
	server->peer.ssl = SSL_new(ssl_ctx);
	SSL_set_fd(server->peer.ssl, server->sock);
	if (SSL_connect(server->peer.ssl) > 0)
	    break;
	while ((error = ERR_get_error()))
	    err("tlsconnect: TLS: %s", ERR_error_string(error, NULL));
    }
    printf("tlsconnect: TLS connection to %s port %s up\n", server->peer.host, server->peer.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) {
		printf("radtlsget: connection lost\n");
		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) {
	    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) {
		printf("radtlsget: connection lost\n");
		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);
	printf("radtlsget: packet smaller than minimum radius size\n");
    }
    
    printf("radtlsget: got %d bytes\n", 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->peer.type == 'U') {
	if (send(server->sock, rad, len, 0) >= 0) {
	    printf("clienradput: sent UDP of length %d to %s port %s\n", len, server->peer.host, server->peer.port);
	    return 1;
	}
	err("clientradput: send failed");
	return 0;
    }

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

    server->connectionok = 1;
    printf("clientradput: Sent %d bytes, Radius packet of length %d to TLS peer %s\n",
	   cnt, len, server->peer.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(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(sec)) &&
	      EVP_DigestFinal_ex(&mdctx, hash, &len) &&
	      len == 16 &&
	      !memcmp(hash, rad + 4, 16));
    pthread_mutex_unlock(&lock);
    return result;
}
	      
int checkmessageauth(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) {
	printf("message auth computation failed\n");
	pthread_mutex_unlock(&lock);
	return 0;
    }

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

int createmessageauth(char *rad, 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) {
	printf("message auth computation failed\n");
	pthread_mutex_unlock(&lock);
	return 0;
    }

    pthread_mutex_unlock(&lock);
    return 1;
}

void sendrq(struct server *to, struct client *from, struct request *rq) {
    int i;
    
    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) {
	    printf("No room in queue, dropping request\n");
	    pthread_mutex_unlock(&to->newrq_mutex);
	    return;
	}
    }
    
    to->nextid = i + 1;
    rq->buf[1] = (char)i;
    printf("sendrq: inserting packet with id %d in queue for %s\n", i, to->peer.host);
    
    if (!createmessageauth(rq->buf, rq->messageauthattrval, to->peer.secret))
	return;

    gettimeofday(&rq->expiry, NULL);
    rq->expiry.tv_sec += 30;
    to->requests[i] = *rq;

    if (!to->newrq) {
	to->newrq = 1;
	printf("signalling client writer\n");
	pthread_cond_signal(&to->newrq_cond);
    }
    pthread_mutex_unlock(&to->newrq_mutex);
}

void sendreply(struct client *to, struct server *from, char *buf, struct sockaddr_storage *tosa) {
    struct replyq *replyq = to->replyq;
    
    pthread_mutex_lock(&replyq->count_mutex);
    if (replyq->count == replyq->size) {
	printf("No room in queue, dropping request\n");
	pthread_mutex_unlock(&replyq->count_mutex);
	return;
    }

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

    if (replyq->count == 1) {
	printf("signalling client writer\n");
	pthread_cond_signal(&replyq->count_cond);
    }
    pthread_mutex_unlock(&replyq->count_mutex);
}

int pwdencrypt(uint8_t *in, uint8_t len, uint8_t *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, 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, uint8_t *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, 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 server *id2server(char *id, uint8_t len) {
    int i;
    char **realm, *idrealm;

    idrealm = strchr(id, '@');
    if (idrealm) {
	idrealm++;
	len -= idrealm - id;
    } else {
	idrealm = "-";
	len = 1;
    }
    for (i = 0; i < server_count; i++) {
	for (realm = servers[i].realms; *realm; realm++) {
	    if ((strlen(*realm) == 1 && **realm == '*') ||
		(strlen(*realm) == len && !memcmp(idrealm, *realm, len))) {
		printf("found matching realm: %s, host %s\n", *realm, servers[i].peer.host);
		return servers + i;
	    }
	}
    }
    return NULL;
}

struct server *radsrv(struct request *rq, char *buf, struct client *from) {
    uint8_t code, id, *auth, *attr, attrvallen;
    uint8_t *usernameattr = NULL, *userpwdattr = NULL, *tunnelpwdattr = NULL, *messageauthattr = NULL;
    int i;
    uint16_t len;
    int left;
    struct server *to;
    unsigned char newauth[16];
    
    code = *(uint8_t *)buf;
    id = *(uint8_t *)(buf + 1);
    len = RADLEN(buf);
    auth = (uint8_t *)(buf + 4);

    printf("radsrv: code %d, id %d, length %d\n", code, id, len);
    
    if (code != RAD_Access_Request) {
	printf("radsrv: server currently accepts only access-requests, ignoring\n");
	return NULL;
    }

    left = len - 20;
    attr = buf + 20;
    
    while (left > 1) {
	left -= attr[RAD_Attr_Length];
	if (left < 0) {
	    printf("radsrv: attribute length exceeds packet length, ignoring packet\n");
	    return NULL;
	}
	switch (attr[RAD_Attr_Type]) {
	case RAD_Attr_User_Name:
	    usernameattr = attr;
	    break;
	case RAD_Attr_User_Password:
	    userpwdattr = attr;
	    break;
	case RAD_Attr_Tunnel_Password:
	    tunnelpwdattr = attr;
	    break;
	case RAD_Attr_Message_Authenticator:
	    messageauthattr = attr;
	    break;
	}
	attr += attr[RAD_Attr_Length];
    }
    if (left)
	printf("radsrv: malformed packet? remaining byte after last attribute\n");

    if (usernameattr) {
	printf("radsrv: Username: ");
	for (i = 0; i < usernameattr[RAD_Attr_Length] - 2; i++)
	    printf("%c", usernameattr[RAD_Attr_Value + i]);
	printf("\n");
    }

    to = id2server(&usernameattr[RAD_Attr_Value], usernameattr[RAD_Attr_Length] - 2);
    if (!to) {
	printf("radsrv: ignoring request, don't know where to send it\n");
	return NULL;
    }
    
    if (messageauthattr && (messageauthattr[RAD_Attr_Length] != 18 ||
			    !checkmessageauth(buf, &messageauthattr[RAD_Attr_Value], from->peer.secret))) {
	printf("radsrv: message authentication failed\n");
	return NULL;
    }

    if (!RAND_bytes(newauth, 16)) {
	printf("radsrv: failed to generate random auth\n");
	return NULL;
    }

    printauth("auth", auth);
    printauth("newauth", newauth);
    
    if (userpwdattr) {
	printf("radsrv: found userpwdattr of length %d\n", userpwdattr[RAD_Attr_Length]);
	attrvallen = userpwdattr[RAD_Attr_Length] - 2;
	if (attrvallen < 16 || attrvallen > 128 || attrvallen % 16) {
	    printf("radsrv: invalid user password length\n");
	    return NULL;
	}
	
	if (!pwddecrypt(&userpwdattr[RAD_Attr_Value], attrvallen, from->peer.secret, strlen(from->peer.secret), auth)) {
	    printf("radsrv: cannot decrypt password\n");
	    return NULL;
	}
	printf("radsrv: password: ");
	for (i = 0; i < attrvallen; i++)
	    printf("%02x ", userpwdattr[RAD_Attr_Value + i]);
	printf("\n");
	if (!pwdencrypt(&userpwdattr[RAD_Attr_Value], attrvallen, to->peer.secret, strlen(to->peer.secret), newauth)) {
	    printf("radsrv: cannot encrypt password\n");
	    return NULL;
	}
    }

    if (tunnelpwdattr) {
	printf("radsrv: found tunnelpwdattr of length %d\n", tunnelpwdattr[RAD_Attr_Length]);
	attrvallen = tunnelpwdattr[RAD_Attr_Length] - 2;
	if (attrvallen < 16 || attrvallen > 128 || attrvallen % 16) {
	    printf("radsrv: invalid user password length\n");
	    return NULL;
	}
	
	if (!pwddecrypt(&tunnelpwdattr[RAD_Attr_Value], attrvallen, from->peer.secret, strlen(from->peer.secret), auth)) {
	    printf("radsrv: cannot decrypt password\n");
	    return NULL;
	}
	printf("radsrv: password: ");
	for (i = 0; i < attrvallen; i++)
	    printf("%02x ", tunnelpwdattr[RAD_Attr_Value + i]);
	printf("\n");
	if (!pwdencrypt(&tunnelpwdattr[RAD_Attr_Value], attrvallen, to->peer.secret, strlen(to->peer.secret), newauth)) {
	    printf("radsrv: cannot encrypt password\n");
	    return NULL;
	}
    }

    rq->buf = buf;
    rq->from = from;
    rq->origid = id;
    rq->messageauthattrval = (messageauthattr ? &messageauthattr[RAD_Attr_Value] : NULL);
    memcpy(rq->origauth, auth, 16);
    memcpy(auth, newauth, 16);
    printauth("rq->origauth", rq->origauth);
    printauth("auth", auth);
    return to;
}

void *clientrd(void *arg) {
    struct server *server = (struct server *)arg;
    struct client *from;
    int i, left, subleft;
    unsigned char *buf, *messageauthattr, *subattr, *attr;
    struct sockaddr_storage fromsa;
    struct timeval lastconnecttry;
    char tmp[255];
    
    for (;;) {
    getnext:
	lastconnecttry = server->lastconnecttry;
	buf = (server->peer.type == 'U' ? radudpget(server->sock, NULL, &server, NULL) : radtlsget(server->peer.ssl));
	if (!buf && server->peer.type == 'T') {
	    tlsconnect(server, &lastconnecttry, "clientrd");
	    continue;
	}
    
	server->connectionok = 1;

	if (*buf != RAD_Access_Accept && *buf != RAD_Access_Reject && *buf != RAD_Access_Challenge) {
	    printf("clientrd: discarding, only accept access accept, access reject and access challenge messages\n");
	    continue;
	}
	
	i = buf[1]; /* i is the id */

	pthread_mutex_lock(&server->newrq_mutex);
	if (!server->requests[i].buf || !server->requests[i].tries) {
	    pthread_mutex_unlock(&server->newrq_mutex);
	    printf("clientrd: no matching request sent with this id, ignoring\n");
	    continue;
	}

	if (server->requests[i].received) {
	    pthread_mutex_unlock(&server->newrq_mutex);
	    printf("clientrd: already received, ignoring\n");
	    continue;
	}
	
	if (!validauth(buf, server->requests[i].buf + 4, server->peer.secret)) {
	    pthread_mutex_unlock(&server->newrq_mutex);
	    printf("clientrd: invalid auth, ignoring\n");
	    continue;
	}
	
	from = server->requests[i].from;


	/* messageauthattr present? */
	messageauthattr = NULL;
	left = RADLEN(buf) - 20;
	attr = buf + 20;
	while (left > 1) {
	    left -= attr[RAD_Attr_Length];
	    if (left < 0) {
		printf("clientrd: attribute length exceeds packet length, ignoring packet\n");
		goto getnext;
	    }
	    if (attr[RAD_Attr_Type] == RAD_Attr_Message_Authenticator) {
		if (attr[RAD_Attr_Length] != 18) {
		    printf("clientrd: illegal message auth attribute length, ignoring packet\n");
		    goto getnext;
		}
		memcpy(tmp, buf + 4, 16);
		memcpy(buf + 4, server->requests[i].buf + 4, 16);
		if (!checkmessageauth(buf, &attr[RAD_Attr_Value], server->peer.secret)) {
		    printf("clientrd: message authentication failed\n");
		    goto getnext;
		}
		memcpy(buf + 4, tmp, 16);
		printf("clientrd: message auth ok\n");
		messageauthattr = attr;
		break;
	    }
	    attr += attr[RAD_Attr_Length];
	}

	/* handle MS MPPE */
	left = RADLEN(buf) - 20;
	attr = buf + 20;
	while (left > 1) {
	    left -= attr[RAD_Attr_Length];
	    if (left < 0) {
		printf("clientrd: attribute length exceeds packet length, ignoring packet\n");
		goto getnext;
	    }
	    if (attr[RAD_Attr_Type] == RAD_Attr_Vendor_Specific &&
		((uint16_t *)attr)[1] == 0 && ntohs(((uint16_t *)attr)[2]) == 311) { // 311 == MS
		subleft = attr[RAD_Attr_Length] - 6;
		subattr = attr + 6;
		while (subleft > 1) {
		    subleft -= subattr[RAD_Attr_Length];
		    if (subleft < 0)
			break;
		    if (subattr[RAD_Attr_Type] != RAD_VS_ATTR_MS_MPPE_Send_Key &&
			subattr[RAD_Attr_Type] != RAD_VS_ATTR_MS_MPPE_Recv_Key)
			continue;
		    printf("clientrd: Got MS MPPE\n");
		    if (subattr[RAD_Attr_Length] < 20)
			continue;

		    if (!msmppdecrypt(subattr + 4, subattr[RAD_Attr_Length] - 4,
			    server->peer.secret, strlen(server->peer.secret), server->requests[i].buf + 4, subattr + 2)) {
			printf("clientrd: failed to decrypt msppe key\n");
			continue;
		    }

		    if (!msmppencrypt(subattr + 4, subattr[RAD_Attr_Length] - 4,
			    from->peer.secret, strlen(from->peer.secret), server->requests[i].origauth, subattr + 2)) {
			printf("clientrd: failed to encrypt msppe key\n");
			continue;
		    }
		}
		if (subleft < 0) {
		    printf("clientrd: bad vendor specific attr or subattr length, ignoring packet\n");
		    goto getnext;
		}
	    }
	    attr += attr[RAD_Attr_Length];
	}

	/* once we set received = 1, requests[i] may be reused */
	buf[1] = (char)server->requests[i].origid;
	memcpy(buf + 4, server->requests[i].origauth, 16);
	printauth("origauth/buf+4", buf + 4);
	if (messageauthattr) {
	    if (!createmessageauth(buf, &messageauthattr[RAD_Attr_Value], from->peer.secret))
		continue;
	    printf("clientrd: computed messageauthattr\n");
	}

	if (from->peer.type == 'U')
	    fromsa = server->requests[i].fromsa;
	server->requests[i].received = 1;
	pthread_mutex_unlock(&server->newrq_mutex);

	if (!radsign(buf, from->peer.secret)) {
	    printf("clientrd: failed to sign message\n");
	    continue;
	}
	printauth("signedorigauth/buf+4", buf + 4);		
	printf("clientrd: giving packet back to where it came from\n");
	sendreply(from, server, buf, from->peer.type == 'U' ? &fromsa : NULL);
    }
}

void *clientwr(void *arg) {
    struct server *server = (struct server *)arg;
    struct request *rq;
    pthread_t clientrdth;
    int i;
    struct timeval now;
    
    if (server->peer.type == 'U') {
	if ((server->sock = connecttoserver(server->peer.addrinfo)) < 0) {
	    printf("clientwr: connecttoserver failed\n");
	    exit(1);
	}
    } else
	tlsconnect(server, NULL, "new client");
    
    if (pthread_create(&clientrdth, NULL, clientrd, (void *)server))
	errx("clientwr: pthread_create failed");

    for (;;) {
	pthread_mutex_lock(&server->newrq_mutex);
	while (!server->newrq) {
	    printf("clientwr: waiting for signal\n");
	    pthread_cond_wait(&server->newrq_cond, &server->newrq_mutex);
	    printf("clientwr: got signal\n");
	}
	server->newrq = 0;
	pthread_mutex_unlock(&server->newrq_mutex);
	       
	for (i = 0; i < MAX_REQUESTS; i++) {
	    pthread_mutex_lock(&server->newrq_mutex);
	    while (!server->requests[i].buf && i < MAX_REQUESTS)
		i++;
	    if (i == MAX_REQUESTS) {
		pthread_mutex_unlock(&server->newrq_mutex);
		break;
	    }

	    gettimeofday(&now, NULL);
	    rq = server->requests + i;

            if (rq->received) {
		printf("clientwr: removing received packet from queue\n");
                free(rq->buf);
                /* setting this to NULL means that it can be reused */
                rq->buf = NULL;
                pthread_mutex_unlock(&server->newrq_mutex);
                continue;
            }
            if (now.tv_sec > rq->expiry.tv_sec) {
		printf("clientwr: removing expired packet from queue\n");
                free(rq->buf);
                /* setting this to NULL means that it can be reused */
                rq->buf = NULL;
                pthread_mutex_unlock(&server->newrq_mutex);
                continue;
            }

	    if (rq->tries)
		continue; // not re-sending (yet)
	    
	    rq->tries++;
            pthread_mutex_unlock(&server->newrq_mutex);
            
	    clientradput(server, server->requests[i].buf);
	}
    }
    /* should do more work to maintain TLS connections, keepalives etc */
}

void *udpserverwr(void *arg) {
    struct replyq *replyq = &udp_server_replyq;
    struct reply *reply = replyq->replies;
    
    pthread_mutex_lock(&replyq->count_mutex);
    for (;;) {
	while (!replyq->count) {
	    printf("udp server writer, waiting for signal\n");
	    pthread_cond_wait(&replyq->count_cond, &replyq->count_mutex);
	    printf("udp server writer, got signal\n");
	}
	pthread_mutex_unlock(&replyq->count_mutex);
	
	if (sendto(udp_server_sock, reply->buf, RADLEN(reply->buf), 0,
		   (struct sockaddr *)&reply->tosa, SOCKADDR_SIZE(reply->tosa)) < 0)
	    err("sendudp: send failed");
	free(reply->buf);
	
	pthread_mutex_lock(&replyq->count_mutex);
	replyq->count--;
	memmove(replyq->replies, replyq->replies + 1,
		replyq->count * sizeof(struct reply));
    }
}

void *udpserverrd(void *arg) {
    struct request rq;
    unsigned char *buf;
    struct server *to;
    struct client *fr;
    pthread_t udpserverwrth;
    
    if ((udp_server_sock = bindport(SOCK_DGRAM, options.udpserverport)) < 0) {
        printf("udpserverrd: socket/bind failed\n");
	exit(1);
    }
    printf("udpserverrd: listening on UDP port %s\n", options.udpserverport);

    if (pthread_create(&udpserverwrth, NULL, udpserverwr, NULL))
	errx("pthread_create failed");
    
    for (;;) {
	fr = NULL;
	memset(&rq, 0, sizeof(struct request));
	buf = radudpget(udp_server_sock, &fr, NULL, &rq.fromsa);
	to = radsrv(&rq, buf, fr);
	if (!to) {
	    printf("udpserverrd: ignoring request, no place to send it\n");
	    continue;
	}
	sendrq(to, fr, &rq);
    }
}

void *tlsserverwr(void *arg) {
    int cnt;
    unsigned long error;
    struct client *client = (struct client *)arg;
    struct replyq *replyq;
    
    printf("tlsserverwr starting for %s\n", client->peer.host);
    replyq = client->replyq;
    pthread_mutex_lock(&replyq->count_mutex);
    for (;;) {
	while (!replyq->count) {
	    if (client->peer.ssl) {	    
		printf("tls server writer, waiting for signal\n");
		pthread_cond_wait(&replyq->count_cond, &replyq->count_mutex);
		printf("tls server writer, got signal\n");
	    }
	    if (!client->peer.ssl) {
		//ssl might have changed while waiting
		pthread_mutex_unlock(&replyq->count_mutex);
		printf("tlsserverwr: exiting as requested\n");
		pthread_exit(NULL);
	    }
	}
	pthread_mutex_unlock(&replyq->count_mutex);
	cnt = SSL_write(client->peer.ssl, replyq->replies->buf, RADLEN(replyq->replies->buf));
	if (cnt > 0)
	    printf("tlsserverwr: Sent %d bytes, Radius packet of length %d\n",
		   cnt, RADLEN(replyq->replies->buf));
	else
	    while ((error = ERR_get_error()))
		err("tlsserverwr: SSL: %s", ERR_error_string(error, NULL));
	free(replyq->replies->buf);

	pthread_mutex_lock(&replyq->count_mutex);
	replyq->count--;
	memmove(replyq->replies, replyq->replies + 1, replyq->count * sizeof(struct reply));
    }
}

void *tlsserverrd(void *arg) {
    struct request rq;
    char unsigned *buf;
    unsigned long error;
    struct server *to;
    int s;
    struct client *client = (struct client *)arg;
    pthread_t tlsserverwrth;
    SSL *ssl;
    
    printf("tlsserverrd starting for %s\n", client->peer.host);
    ssl = client->peer.ssl;

    if (SSL_accept(ssl) <= 0) {
        while ((error = ERR_get_error()))
            err("tlsserverrd: SSL: %s", ERR_error_string(error, NULL));
        errx("accept failed, child exiting");
    }

    if (pthread_create(&tlsserverwrth, NULL, tlsserverwr, (void *)client))
	errx("pthread_create failed");
    
    for (;;) {
	buf = radtlsget(client->peer.ssl);
	if (!buf)
	    break;
	printf("tlsserverrd: got Radius message from %s\n", client->peer.host);
	memset(&rq, 0, sizeof(struct request));
	to = radsrv(&rq, buf, client);
	if (!to) {
	    printf("ignoring request, no place to send it\n");
	    continue;
	}
	sendrq(to, client, &rq);
    }
    printf("tlsserverrd: connection lost\n");
    // stop writer by setting peer.ssl to NULL and give signal in case waiting for data
    client->peer.ssl = NULL;
    pthread_mutex_lock(&client->replyq->count_mutex);
    pthread_cond_signal(&client->replyq->count_cond);
    pthread_mutex_unlock(&client->replyq->count_mutex);
    printf("tlsserverrd: waiting for writer to end\n");
    pthread_join(tlsserverwrth, NULL);
    s = SSL_get_fd(ssl);
    SSL_free(ssl);
    close(s);
    printf("tlsserverrd thread for %s exiting\n", client->peer.host);
    pthread_exit(NULL);
}

int tlslistener() {
    pthread_t tlsserverth;
    int s, snew;
    struct sockaddr_storage from;
    size_t fromlen = sizeof(from);
    struct client *client;

    if ((s = bindport(SOCK_STREAM, DEFAULT_TLS_PORT)) < 0) {
        printf("tlslistener: socket/bind failed\n");
	exit(1);
    }
    
    listen(s, 0);
    printf("listening for incoming TLS on port %s\n", DEFAULT_TLS_PORT);

    for (;;) {
	snew = accept(s, (struct sockaddr *)&from, &fromlen);
	if (snew < 0)
	    errx("accept failed");
	printf("incoming TLS connection from %s\n", addr2string((struct sockaddr *)&from, fromlen));

	client = find_client('T', (struct sockaddr *)&from, NULL);
	if (!client) {
	    printf("ignoring request, not a known TLS client\n");
	    shutdown(snew, SHUT_RDWR);
	    close(snew);
	    continue;
	}

	if (client->peer.ssl) {
	    printf("Ignoring incoming connection, already have one from this client\n");
	    shutdown(snew, SHUT_RDWR);
	    close(snew);
	    continue;
	}
	client->peer.ssl = SSL_new(ssl_ctx);
	SSL_set_fd(client->peer.ssl, snew);
	if (pthread_create(&tlsserverth, NULL, tlsserverrd, (void *)client))
	    errx("pthread_create failed");
	pthread_detach(tlsserverth);
    }
    return 0;
}

char *parsehostport(char *s, struct peer *peer) {
    char *p, *field;
    int ipv6 = 0;

    p = s;
    // allow literal addresses and port, e.g. [2001:db8::1]:1812
    if (*p == '[') {
	p++;
	field = p;
	for (; *p && *p != ']' && *p != ' ' && *p != '\t' && *p != '\n'; p++);
	if (*p != ']') {
	    printf("no ] matching initial [\n");
	    exit(1);
	}
	ipv6 = 1;
    } else {
	field = p;
	for (; *p && *p != ':' && *p != ' ' && *p != '\t' && *p != '\n'; p++);
    }
    if (field == p) {
	printf("missing host/address\n");
	exit(1);
    }
    peer->host = stringcopy(field, p - field);
    if (ipv6) {
	p++;
	if (*p && *p != ':' && *p != ' ' && *p != '\t' && *p != '\n') {
	    printf("unexpected character after ]\n");
	    exit(1);
	}
    }
    if (*p == ':') {
	    /* port number or service name is specified */;
	    field = p++;
	    for (;