SASL Client Example

The following code listing is for the sample client in SASL Example.

#pragma ident    "@(#)client.c    1.4    03/04/07 SMI"
/* $Id: client.c,v 1.3 2002/09/03 15:11:59 rjs3 Exp $ */
/* 
 * Copyright (c) 2001 Carnegie Mellon University.  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.
 *
 * 3. The name "Carnegie Mellon University" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For permission or any other legal
 *    details, please contact  
 *      Office of Technology Transfer
 *      Carnegie Mellon University
 *      5000 Forbes Avenue
 *      Pittsburgh, PA  15213-3890
 *      (412) 268-4387, fax: (412) 268-7395
 *      tech-transfer@andrew.cmu.edu
 *
 * 4. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by Computing Services
 *     at Carnegie Mellon University (http://www.cmu.edu/computing/)."
 *
 * CARNEGIE MELLON UNIVERSITY DISCLAIMS ALL WARRANTIES WITH REGARD TO
 * THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS, IN NO EVENT SHALL CARNEGIE MELLON UNIVERSITY BE LIABLE
 * FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
 * AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <config.h>

#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <ctype.h>
#include <errno.h>
#include <string.h>

#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#ifdef _SUN_SDK_
#include <sysexits.h>
#endif /* _SUN_SDK_ */

#include <assert.h>

#include <sasl.h>

#include "common.h"

/* remove \r\n at end of the line */
static void chop(char *s)
{
    char *p;

    assert(s);
    p = s + strlen(s) - 1;
    if (p[0] == '\n') {
    *p-- = '\0';
    }
    if (p >= s && p[0] == '\r') {
    *p-- = '\0';
    }
}

static int getrealm(void *context __attribute__((unused)), 
            int id,
            const char **availrealms,
            const char **result)
{
    static char buf[1024];

    /* Double-check the ID */
    if (id != SASL_CB_GETREALM) return SASL_BADPARAM;
    if (!result) return SASL_BADPARAM;

    printf("please choose a realm (available:");
    while (*availrealms) {
    printf(" %s", *availrealms);
    availrealms++;
    }
    printf("): ");

    fgets(buf, sizeof buf, stdin);
    chop(buf);
    *result = buf;
  
    return SASL_OK;
}

static int simple(void *context __attribute__((unused)),
          int id,
          const char **result,
          unsigned *len)
{
    static char buf[1024];

    /* Double-check the connection */
    if (! result)
    return SASL_BADPARAM;

    switch (id) {
    case SASL_CB_USER:
    printf("please enter an authorization id: ");
    break;
    case SASL_CB_AUTHNAME:
    printf("please enter an authentication id: ");
    break;
    default:
    return SASL_BADPARAM;
    }

    fgets(buf, sizeof buf, stdin);
    chop(buf);
    *result = buf;
    if (len) *len = strlen(buf);
  
    return SASL_OK;
}

#ifndef HAVE_GETPASSPHRASE
static char *
getpassphrase(const char *prompt)
{
  return getpass(prompt);
}
#endif /* ! HAVE_GETPASSPHRASE */

static int
getsecret(sasl_conn_t *conn,
      void *context __attribute__((unused)),
      int id,
      sasl_secret_t **psecret)
{
    char *password;
    size_t len;
    static sasl_secret_t *x;

    /* paranoia check */
    if (! conn || ! psecret || id != SASL_CB_PASS)
    return SASL_BADPARAM;

    password = getpassphrase("Password: ");
    if (! password)
    return SASL_FAIL;

    len = strlen(password);

    x = (sasl_secret_t *) realloc(x, sizeof(sasl_secret_t) + len);
  
    if (!x) {
    memset(password, 0, len);
    return SASL_NOMEM;
    }

    x->len = len;
#ifdef _SUN_SDK_
    strcpy((char *)x->data, password);
#else
    strcpy(x->data, password);
#endif /* _SUN_SDK_ */
    memset(password, 0, len);
    
    *psecret = x;
    return SASL_OK;
}

static int getpath(void * context __attribute__((unused)),
    const char **path)
{
    *path = getenv("SASL_PATH");

    if (*path == NULL)
    *path = PLUGINDIR;

    return SASL_OK;
}

/* callbacks we support */
static sasl_callback_t callbacks[] = {
  {
    SASL_CB_GETREALM, &getrealm, NULL
  }, {
    SASL_CB_USER, &simple, NULL
  }, {
    SASL_CB_AUTHNAME, &simple, NULL
  }, {
    SASL_CB_PASS, &getsecret, NULL
  }, {
    SASL_CB_GETPATH, &getpath, NULL
  }, {
    SASL_CB_LIST_END, NULL, NULL
  }
};

int getconn(const char *host, const char *port)
{
    struct addrinfo hints, *ai, *r;
    int err, sock = -1;

    memset(&hints, 0, sizeof(hints));
    hints.ai_family = PF_UNSPEC;
    hints.ai_socktype = SOCK_STREAM;

    if ((err = getaddrinfo(host, port, &hints, &ai)) != 0) {
    fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(err));
    exit(EX_UNAVAILABLE);
    }

    for (r = ai; r; r = r->ai_next) {
    sock = socket(r->ai_family, r->ai_socktype, r->ai_protocol);
    if (sock < 0)
        continue;
    if (connect(sock, r->ai_addr, r->ai_addrlen) >= 0)
        break;
    close(sock);
    sock = -1;
    }

    freeaddrinfo(ai);
    if (sock < 0) {
    perror("connect");
    exit(EX_UNAVAILABLE);
    }

    return sock;
}

char *mech;

int mysasl_negotiate(FILE *in, FILE *out, sasl_conn_t *conn)
{
    char buf[8192];
    const char *data;
    const char *chosenmech;
#ifdef _SUN_SDK_
    unsigned len;
#else
    int len;
#endif /* _SUN_SDK_ */
    int r, c;

    /* get the capability list */
    dprintf(0, "receiving capability list... ");
    len = recv_string(in, buf, sizeof buf);
    dprintf(0, "%s\n", buf);

    if (mech) {
    /* make sure that 'mech' appears in 'buf' */
    if (!strstr(buf, mech)) {
        printf("server doesn't offer mandatory mech '%s'\n", mech);
        return -1;
    }
    } else {
    mech = buf;
    }

    r = sasl_client_start(conn, mech, NULL, &data, &len, &chosenmech);
    if (r != SASL_OK && r != SASL_CONTINUE) {
    saslerr(r, "starting SASL negotiation");
    printf("\n%s\n", sasl_errdetail(conn));
    return -1;
    }
    
    dprintf(1, "using mechanism %s\n", chosenmech);

    /* we send up to 3 strings;
       the mechanism chosen, the presence of initial response,
       and optionally the initial response */
    send_string(out, chosenmech, strlen(chosenmech));
    if(data) {
    send_string(out, "Y", 1);
    send_string(out, data, len);
    } else {
    send_string(out, "N", 1);
    }

    for (;;) {
    dprintf(2, "waiting for server reply...\n");

    c = fgetc(in);
    switch (c) {
    case 'O':
        goto done_ok;

    case 'N':
        goto done_no;

    case 'C': /* continue authentication */
        break;

    default:
        printf("bad protocol from server (%c %x)\n", c, c);
        return -1;
    }
    len = recv_string(in, buf, sizeof buf);

    r = sasl_client_step(conn, buf, len, NULL, &data, &len);
    if (r != SASL_OK && r != SASL_CONTINUE) {
        saslerr(r, "performing SASL negotiation");
        printf("\n%s\n", sasl_errdetail(conn));
        return -1;
    }

    if (data) {
        dprintf(2, "sending response length %d...\n", len);
        send_string(out, data, len);
    } else {
        dprintf(2, "sending null response...\n");
        send_string(out, "", 0);
    }
    }

 done_ok:
    printf("successful authentication\n");
    return 0;

 done_no:
    printf("authentication failed\n");
    return -1;
}

#ifdef _SUN_SDK_
void usage(const char *s)
#else
void usage(void)
#endif /* _SUN_SDK_ */
{
#ifdef _SUN_SDK_
    fprintf(stderr, "usage: %s [-p port] [-s service] [-m mech] host\n", s);
#else
    fprintf(stderr, "usage: client [-p port] [-s service] \
        [-m mech] host\n");
#endif /* _SUN_SDK_ */
    exit(EX_USAGE);
}

int main(int argc, char *argv[])
{
    int c;
    char *host = "localhost";
    char *port = "12345";
    char localaddr[NI_MAXHOST + NI_MAXSERV],
    remoteaddr[NI_MAXHOST + NI_MAXSERV];
    char *service = "rcmd";
    char hbuf[NI_MAXHOST], pbuf[NI_MAXSERV];
    int r;
    sasl_conn_t *conn;
    FILE *in, *out;
    int fd;
    int salen;
    struct sockaddr_storage local_ip, remote_ip;

    while ((c = getopt(argc, argv, "p:s:m:")) != EOF) {
    switch(c) {
    case 'p':
        port = optarg;
        break;

    case 's':
        service = optarg;
        break;

    case 'm':
        mech = optarg;
        break;

    default:
#ifdef _SUN_SDK_
        usage(argv[0]);
#else
        usage();
#endif /* _SUN_SDK_ */
        break;
    }
    }

    if (optind > argc - 1) {
#ifdef _SUN_SDK_
    usage(argv[0]);
#else
    usage();
#endif /* _SUN_SDK_ */
    }
    if (optind == argc - 1) {
    host = argv[optind];
    }

    /* initialize the sasl library */
    r = sasl_client_init(callbacks);
    if (r != SASL_OK) saslfail(r, "initializing libsasl");

    /* connect to remote server */
    fd = getconn(host, port);

    /* set ip addresses */
    salen = sizeof(local_ip);
    if (getsockname(fd, (struct sockaddr *)&local_ip, &salen) < 0) {
    perror("getsockname");
    }

    getnameinfo((struct sockaddr *)&local_ip, salen,
        hbuf, sizeof(hbuf), pbuf, sizeof(pbuf),
#ifdef _SUN_SDK_    /* SOLARIS doesn't support NI_WITHSCOPEID */
        NI_NUMERICHOST | NI_NUMERICSERV);
#else
        NI_NUMERICHOST | NI_WITHSCOPEID | NI_NUMERICSERV);
#endif
    snprintf(localaddr, sizeof(localaddr), "%s;%s", hbuf, pbuf);

    salen = sizeof(remote_ip);
    if (getpeername(fd, (struct sockaddr *)&remote_ip, &salen) < 0) {
    perror("getpeername");
    }

    getnameinfo((struct sockaddr *)&remote_ip, salen,
        hbuf, sizeof(hbuf), pbuf, sizeof(pbuf),
#ifdef _SUN_SDK_    /* SOLARIS doesn't support NI_WITHSCOPEID */
        NI_NUMERICHOST | NI_NUMERICSERV);
#else
        NI_NUMERICHOST | NI_WITHSCOPEID | NI_NUMERICSERV);
#endif
    snprintf(remoteaddr, sizeof(remoteaddr), "%s;%s", hbuf, pbuf);

    /* client new connection */
    r = sasl_client_new(service, host, localaddr, remoteaddr, NULL, 
        0, &conn);
    if (r != SASL_OK) saslfail(r, "allocating connection state");

    /* set external properties here
       sasl_setprop(conn, SASL_SSF_EXTERNAL, &extprops); */

    /* set required security properties here
       sasl_setprop(conn, SASL_SEC_PROPS, &secprops); */

    in = fdopen(fd, "r");
    out = fdopen(fd, "w");

    r = mysasl_negotiate(in, out, conn);
    if (r == SASL_OK) {
    /* send/receive data */
    
    
    }
    
    printf("closing connection\n");
    fclose(in);
    fclose(out);
    close(fd);
    sasl_dispose(&conn);

    sasl_done();

    return 0;
}