squid_rad_auth.c

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/*
 *      RADIUS
 *      Remote Authentication Dial In User Service
 *
 *
 *      Livingston Enterprises, Inc.
 *      6920 Koll Center Parkway
 *      Pleasanton, CA   94566
 *
 *      Copyright 1992 Livingston Enterprises, Inc.
 *
 *      Permission to use, copy, modify, and distribute this software for any
 *      purpose and without fee is hereby granted, provided that this
 *      copyright and permission notice appear on all copies and supporting
 *      documentation, the name of Livingston Enterprises, Inc. not be used
 *      in advertising or publicity pertaining to distribution of the
 *      program without specific prior permission, and notice be given
 *      in supporting documentation that copying and distribution is by
 *      permission of Livingston Enterprises, Inc.   
 *
 *      Livingston Enterprises, Inc. makes no representations about
 *      the suitability of this software for any purpose.  It is
 *      provided "as is" without express or implied warranty.
 *
 * The new parts of the code is Copyright (C) 1998 R.M. van Selm <[e-mail]>
 * with modifications
 *      Copyright (C) 2004 Henrik Nordstrom <[e-mail]>
 *      Copyright (C) 2006 Henrik Nordstrom <[e-mail]>
 */

/* Squid_rad_auth is a RADIUS authenticator for Squid-2.5 and later.
 * The authenticator reads a line with a user and password combination.
 * If access is granted OK is returned. Else ERR.
 *
 * Squid_rad_auth-1.0 is based on modules from the Cistron-radiusd-1.5.4.
 *
 * Currently you should only start 1 authentificator at a time because the
 * the ID's of the different programs can start to conflict. I'm not sure it
 * would help anyway. I think the RADIUS server is close by and I don't think
 * it will handle requests in parallel anyway (correct me if I'm wrong here)
 *
 * Marc van Selm <[e-mail]>
 * with contributions from
 * Henrik Nordstrom <[e-mail]>
 * and many others
 */

#include	"config.h"

#if HAVE_SYS_TYPES_H
#include	<sys/types.h>
#endif
#if HAVE_SYS_SOCKET_H
#include	<sys/socket.h>
#endif
#if HAVE_NETINET_IN_H
#include	<netinet/in.h>
#endif
#if HAVE_SYS_TIME_H
#include	<sys/time.h>
#endif
#if HAVE_UNISTD_H
#include	<unistd.h>
#endif
#if HAVE_FCNTL_H
#include	<fcntl.h>
#endif

#if HAVE_CTYPE_H
#include	<ctype.h>
#endif
#if HAVE_STDIO_H
#include	<stdio.h>
#endif
#if HAVE_UNISTD_H
#include	<unistd.h>
#endif
#if HAVE_NETDB_H
#include	<netdb.h>
#endif
#if HAVE_PWD_H
#include	<pwd.h>
#endif
#if HAVE_STDLIB_H
#include	<stdlib.h>
#endif
#if HAVE_TIME_H
#include	<time.h>
#endif
#if HAVE_STRING_H
#include	<string.h>
#endif

#include	"md5.h"
#include	"radius.h"
#include	"util.h"

#define MAXPWNAM	254
#define MAXPASS		254
#define MAXLINE         254


static int i_send_buffer[2048];
static int i_recv_buffer[2048];
static char *send_buffer = (char *) i_send_buffer;
static char *recv_buffer = (char *) i_recv_buffer;
static int sockfd;
static u_char request_id;
static char vector[AUTH_VECTOR_LEN];
static char secretkey[MAXPASS + 1] = "";
static char server[MAXLINE] = "";
static char identifier[MAXLINE] = "";
static char svc_name[MAXLINE] = "radius";
static int nasport = 111;
static int nasporttype = 0;
static u_int32_t nas_ipaddr;
static u_int32_t auth_ipaddr;
static int retries = 30;

char *progname = "squid_rad_auth";
int debug_flag = 0;

/*
 *    Diff two timeval, b - a
 */
static int
timeval_diff(const struct timeval *a, const struct timeval *b)
{
    return (b->tv_sec - a->tv_sec) * 1000000 + (b->tv_usec - a->tv_usec);
}

/*
 *    Time since a timeval
 */
static int
time_since(const struct timeval *when)
{
    struct timeval now;
    gettimeofday(&now, NULL);
    return timeval_diff(when, &now);
}

/*
 *     MD5 digest
 */
static void
md5_calc(uint8_t out[16], void *in, size_t len)
{
    MD5_CTX ctx;
    MD5Init(&ctx);
    MD5Update(&ctx, in, len);
    MD5Final(out, &ctx);
}

/*
 *    Receive and verify the result.
 */
static int
result_recv(u_int32_t host, u_short udp_port, char *buffer, int length)
{
    AUTH_HDR *auth;
    int totallen;
    unsigned char reply_digest[AUTH_VECTOR_LEN];
    unsigned char calc_digest[AUTH_VECTOR_LEN];
    int secretlen;
    /* VALUE_PAIR   *req; */

    auth = (AUTH_HDR *) buffer;
    totallen = ntohs(auth->length);

    if (totallen != length) {
	fprintf(stderr,
	    "Squid_rad_auth: Received invalid reply length from server (want %d/ got %d)\n",
	    totallen, length);
	return -1;
    }

    if (auth->id != request_id) {
	/* Duplicate response of an earlier query, ignore */
	return -1;
    }

    /* Verify the reply digest */
    memcpy(reply_digest, auth->vector, AUTH_VECTOR_LEN);
    memcpy(auth->vector, vector, AUTH_VECTOR_LEN);
    secretlen = strlen(secretkey);
    memcpy(buffer + length, secretkey, secretlen);
    md5_calc(calc_digest, (unsigned char *) auth, length + secretlen);

    if (memcmp(reply_digest, calc_digest, AUTH_VECTOR_LEN) != 0) {
	fprintf(stderr, "Warning: Received invalid reply digest from server\n");
	return -1;
    }

    if (auth->code != PW_AUTHENTICATION_ACK)
	return 1;

    return 0;
}


/*
 *    Generate a random vector.
 */
static void
random_vector(char *vector)
{
    int randno;
    int i;

    srand((time(0) ^ rand()) + rand());
    for (i = 0; i < AUTH_VECTOR_LEN;) {
	randno = rand();
	memcpy(vector, &randno, sizeof(int));
	vector += sizeof(int);
	i += sizeof(int);
    }
}

/* read the config file
 * The format should be something like:
 * # squid_rad_auth configuration file
 * # MvS: 28-10-1998
 * server suncone.cistron.nl
 * secret testje
 */
static int
rad_auth_config(const char *cfname)
{
    FILE *cf;
    char line[MAXLINE];
    int srv = 0, crt = 0;

    if ((cf = fopen(cfname, "r")) == NULL) {
	perror(cfname);
	return -1;
    }
    while (fgets(line, MAXLINE, cf) != NULL) {
	if (!memcmp(line, "server", 6))
	    srv = sscanf(line, "server %s", server);
	if (!memcmp(line, "secret", 6))
	    crt = sscanf(line, "secret %s", secretkey);
	if (!memcmp(line, "identifier", 10))
	    sscanf(line, "identifier %s", identifier);
       if (!memcmp(line, "service", 7))
	    sscanf(line, "service %s", svc_name);
       if (!memcmp(line, "port", 4))
	    sscanf(line, "port %s", svc_name);
    }
    if (srv && crt)
	return 0;
    return -1;
}

static void
urldecode(char *dst, const char *src, int size)
{
    char tmp[3];
    tmp[2] = '\0';
    while (*src && size > 1) {
	if (*src == '%' && src[1] != '\0' && src[2] != '\0') {
	    src++;
	    tmp[0] = *src++;
	    tmp[1] = *src++;
	    *dst++ = strtol(tmp, NULL, 16);
	} else {
	    *dst++ = *src++;
	}
	size--;
    }
    *dst++ = '\0';
}

static int
authenticate(int sockfd, const char *username, const char *passwd)
{
    AUTH_HDR *auth;
    u_short total_length;
    u_char *ptr;
    int length;
    char passbuf[MAXPASS];
    u_char md5buf[256];
    int secretlen;
    u_char cbc[AUTH_VECTOR_LEN];
    int i, j;
    u_int32_t ui;
    struct sockaddr_in saremote;
    fd_set readfds;
    socklen_t salen;
    int retry = retries;

    /*
     *    Build an authentication request
     */
    auth = (AUTH_HDR *) send_buffer;
    auth->code = PW_AUTHENTICATION_REQUEST;
    auth->id = ++request_id;
    random_vector(vector);
    memcpy(auth->vector, vector, AUTH_VECTOR_LEN);
    total_length = AUTH_HDR_LEN;
    ptr = auth->data;

    /*
     *    User Name
     */
    *ptr++ = PW_USER_NAME;
    length = strlen(username);
    if (length > MAXPWNAM) {
	length = MAXPWNAM;
    }
    *ptr++ = length + 2;
    memcpy(ptr, username, length);
    ptr += length;
    total_length += length + 2;

    /*
     *    Password
     */
    length = strlen(passwd);
    if (length > MAXPASS) {
	length = MAXPASS;
    }
    memset(passbuf, 0, MAXPASS);
    memcpy(passbuf, passwd, length);

    /* 
     * Length is rounded up to multiple of 16,
     * and the password is encoded in blocks of 16 
     * with cipher block chaining
     */
    length = ((length / AUTH_VECTOR_LEN) + 1) * AUTH_VECTOR_LEN;

    *ptr++ = PW_PASSWORD;
    *ptr++ = length + 2;

    secretlen = strlen(secretkey);
    /* Set up the Cipher block chain */
    memcpy(cbc, auth->vector, AUTH_VECTOR_LEN);
    for (j = 0; j < length; j += AUTH_VECTOR_LEN) {
	/* Calculate the MD5 Digest */
	strcpy((char *)md5buf, secretkey);
	memcpy(md5buf + secretlen, cbc, AUTH_VECTOR_LEN);
	md5_calc(cbc, md5buf, secretlen + AUTH_VECTOR_LEN);

	/* Xor the password into the MD5 digest */
	for (i = 0; i < AUTH_VECTOR_LEN; i++) {
	    *ptr++ = (cbc[i] ^= passbuf[j + i]);
	}
    }
    total_length += length + 2;

    *ptr++ = PW_NAS_PORT_ID;
    *ptr++ = 6;

    ui = htonl(nasport);
    memcpy(ptr, &ui, 4);
    ptr += 4;
    total_length += 6;

    *ptr++ = PW_NAS_PORT_TYPE;
    *ptr++ = 6;

    ui = htonl(nasporttype);
    memcpy(ptr, &ui, 4);
    ptr += 4;
    total_length += 6;

    if (*identifier) {
	int len = strlen(identifier);
	*ptr++ = PW_NAS_ID;
	*ptr++ = len + 2;
	memcpy(ptr, identifier, len);
	ptr += len;
    } else {
	*ptr++ = PW_NAS_IP_ADDRESS;
	*ptr++ = 6;

	ui = htonl(nas_ipaddr);
	memcpy(ptr, &ui, 4);
	ptr += 4;
	total_length += 6;
    }

    /* Klaus Weidner <[e-mail]> changed this
     * from htonl to htons. It might have caused
     * you trouble or not. That depends on the byte
     * order of your system.
     * The symptom was that the radius server
     * ignored the requests, because they had zero 
     * length according to the data header.
     */
    auth->length = htons(total_length);

    while(retry--) {
	int time_spent;
	struct timeval sent;
	/*
	 *    Send the request we've built.
	 */
	gettimeofday(&sent, NULL);
	send(sockfd, (char *) auth, total_length, 0);
	while ((time_spent = time_since(&sent)) < 1000000) {
	    struct timeval tv;
	    int rc, len;
	    if (!time_spent) {
		tv.tv_sec = 1;
		tv.tv_usec = 0;
	    } else {
		tv.tv_sec = 0;
		tv.tv_usec = 1000000 - time_spent;
	    }
	    FD_ZERO(&readfds);
	    FD_SET(sockfd, &readfds);
	    if (select(sockfd + 1, &readfds, NULL, NULL, &tv) == 0)	/* Select timeout */
		break;
	    salen = sizeof(saremote);
	    len = recvfrom(sockfd, recv_buffer, sizeof(i_recv_buffer),
		0, (struct sockaddr *) &saremote, &salen);

	    if (len < 0)
		continue;

	    rc = result_recv(saremote.sin_addr.s_addr, saremote.sin_port, recv_buffer, len);
	    if (rc == 0)
		return 1;
	    if (rc == 1)
	    	return 0;
	}
    }

    fprintf(stderr, "%s: No response from RADIUS server\n", progname);

    return 0;
}

int
main(int argc, char **argv)
{
    struct sockaddr_in salocal;
    struct sockaddr_in saremote;
    struct servent *svp;
    u_short svc_port;
    char username[MAXPWNAM];
    char passwd[MAXPASS];
    char *ptr;
    char authstring[MAXLINE];
    const char *cfname = NULL;
    int err = 0;
    socklen_t salen;
    int c;

    while ((c = getopt(argc, argv, "h:p:f:w:i:t:")) != -1) {
	switch(c) {
	case 'f':
	    cfname = optarg;
	    break;
	case 'h':
	    strcpy(server, optarg);
	    break;
	case 'p':
	    strcpy(svc_name, optarg);
	    break;
	case 'w':
	    strcpy(secretkey, optarg);
	    break;
	case 'i':
	    strcpy(identifier, optarg);
	    break;
	case 't':
	    retries = atoi(optarg);
	    break;
	}
    }
    /* make standard output line buffered */
    if (setvbuf(stdout, NULL, _IOLBF, 0) != 0)
	return 1;

    if (cfname) {
	if (rad_auth_config(cfname) < 0) {
	    fprintf(stderr, "%s: can't open configuration file '%s'.\n", argv[0], cfname);
	    exit(1);
	}
    }

    if (!*server) {
	fprintf(stderr, "%s: Server not specified\n", argv[0]);
	exit(1);
    }

    if (!*secretkey) {
	fprintf(stderr, "%s: Shared secret not specified\n", argv[0]);
	exit(1);
    }

    /*
     *    Open a connection to the server.
     */
    svp = getservbyname(svc_name, "udp");
    if (svp != NULL)
	svc_port = ntohs((u_short) svp->s_port);
    else
	svc_port = atoi(svc_name);
    if (svc_port == 0)
	svc_port = PW_AUTH_UDP_PORT;

    /* Get the IP address of the authentication server */
    if ((auth_ipaddr = get_ipaddr(server)) == 0) {
	fprintf(stderr, "Couldn't find host %s\n", server);
	exit(1);
    }
    sockfd = socket(AF_INET, SOCK_DGRAM, 0);
    if (sockfd < 0) {
	perror("socket");
	exit(1);
    }
    memset(&saremote, 0, sizeof(saremote));
    saremote.sin_family = AF_INET;
    saremote.sin_addr.s_addr = htonl(auth_ipaddr);
    saremote.sin_port = htons(svc_port);

    if (connect(sockfd, (struct sockaddr *) &saremote, sizeof(saremote)) < 0) {
	perror("connect");
	exit(1);
    }
    salen = sizeof(salocal);
    if (getsockname(sockfd, (struct sockaddr *) &salocal, &salen) < 0) {
	perror("getsockname");
	exit(1);
    }
#ifdef O_NONBLOCK
    fcntl(sockfd, F_SETFL, fcntl(sockfd, F_GETFL, 0) | O_NONBLOCK);
#endif
    nas_ipaddr = ntohl(salocal.sin_addr.s_addr);
    while (fgets(authstring, MAXLINE, stdin) != NULL) {
	char *end;
	/* protect me form to long lines */
	if ((end = strchr(authstring, '\n')) == NULL) {
	    err = 1;
	    continue;
	}
	if (err) {
	    printf("ERR\n");
	    err = 0;
	    continue;
	}
	if (strlen(authstring) > MAXLINE) {
	    printf("ERR\n");
	    continue;
	}
	/* Strip off the trailing newline */
	*end = '\0';

	/* Parse out the username and password */
	ptr = authstring;
	while (isspace(*ptr))
	    ptr++;
	if ((end = strchr(ptr, ' ')) == NULL) {
	    printf("ERR\n");	/* No password */
	    continue;
	}
	*end = '\0';
	urldecode(username, ptr, MAXPWNAM);
	ptr = end + 1;
	while (isspace(*ptr))
	    ptr++;
	urldecode(passwd, ptr, MAXPASS);

	if (authenticate(sockfd, username, passwd))
	    printf("OK\n");
	else
	    printf("ERR\n");
    }
    close(sockfd);
    exit(1);
}