Miscellaneous GSS-API Sample Functions
To make the client and server programs work as shown, a number of other functions are required. These functions are used to display values. The functions are not otherwise needed. The functions in this category are as follows:
-
send_token() – Transfers tokens and messages to a recipient
-
recv_token() – Accepts tokens and messages from a sender
-
display_status() – Shows the status returned by the last GSS-API function called
-
write_all() – Writes a buffer to a file
-
read_all() – Reads a file into a buffer
-
display_ctx_flags() – Shows in a readable form information about the current context, such as whether confidentiality or mutual authentication is allowed
-
print_token() – Prints out a token's value
The code for these functions is shown in the following example.
Note –
The source code for this example is also available through the Sun download center. See http://www.sun.com/download/products.xml?id=41912db5.
Example A–3 Code Listings for Miscellaneous GSS-API Functions
/*
* Copyright 1994 by OpenVision Technologies, Inc.
*
* Permission to use, copy, modify, distribute, and sell this software
* and its documentation for any purpose is hereby granted without fee,
* provided that the above copyright notice appears in all copies and
* that both that copyright notice and this permission notice appear in
* supporting documentation, and that the name of OpenVision not be used
* in advertising or publicity pertaining to distribution of the software
* without specific, written prior permission. OpenVision makes no
* representations about the suitability of this software for any
* purpose. It is provided "as is" without express or implied warranty.
*
* OPENVISION DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
* EVENT SHALL OPENVISION 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.
*/
#if !defined(lint) && !defined(__CODECENTER__)
static char *rcsid = "$Header: /cvs/krbdev/krb5/src/appl/gss-sample/\
gss-misc.c, v 1.15 1996/07/22 20:21:20 marc Exp $";
#endif
#include <stdio.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <errno.h>
#include <unistd.h>
#include <string.h>
#include <gssapi/gssapi.h>
#include <gssapi/gssapi_ext.h>
#include <gss-misc.h>
#include <stdlib.h>
FILE *display_file;
static void display_status_1
(char *m, OM_uint32 code, int type);
static int write_all(int fildes, char *buf, unsigned int nbyte)
{
int ret;
char *ptr;
for (ptr = buf; nbyte; ptr += ret, nbyte -= ret) {
ret = write(fildes, ptr, nbyte);
if (ret < 0) {
if (errno == EINTR)
continue;
return(ret);
} else if (ret == 0) {
return(ptr-buf);
}
}
return(ptr-buf);
}
static int read_all(int fildes, char *buf, unsigned int nbyte)
{
int ret;
char *ptr;
for (ptr = buf; nbyte; ptr += ret, nbyte -= ret) {
ret = read(fildes, ptr, nbyte);
if (ret < 0) {
if (errno == EINTR)
continue;
return(ret);
} else if (ret == 0) {
return(ptr-buf);
}
}
return(ptr-buf);
}
/*
* Function: send_token
*
* Purpose: Writes a token to a file descriptor.
*
* Arguments:
*
* s (r) an open file descriptor
* tok (r) the token to write
*
* Returns: 0 on success, -1 on failure
*
* Effects:
*
* send_token writes the token length (as a network long) and then the
* token data to the file descriptor s. It returns 0 on success, and
* -1 if an error occurs or if it could not write all the data.
*/
int send_token(s, tok)
int s;
gss_buffer_t tok;
{
int len, ret;
len = htonl(tok->length);
ret = write_all(s, (char *) &len, 4);
if (ret < 0) {
perror("sending token length");
return -1;
} else if (ret != 4) {
if (display_file)
fprintf(display_file,
"sending token length: %d of %d bytes written\n",
ret, 4);
return -1;
}
ret = write_all(s, tok->value, tok->length);
if (ret < 0) {
perror("sending token data");
return -1;
} else if (ret != tok->length) {
if (display_file)
fprintf(display_file,
"sending token data: %d of %d bytes written\n",
ret, tok->length);
return -1;
}
return 0;
}
/*
* Function: recv_token
*
* Purpose: Reads a token from a file descriptor.
*
* Arguments:
*
* s (r) an open file descriptor
* tok (w) the read token
*
* Returns: 0 on success, -1 on failure
*
* Effects:
*
* recv_token reads the token length (as a network long), allocates
* memory to hold the data, and then reads the token data from the
* file descriptor s. It blocks to read the length and data, if
* necessary. On a successful return, the token should be freed with
* gss_release_buffer. It returns 0 on success, and -1 if an error
* occurs or if it could not read all the data.
*/
int recv_token(s, tok)
int s;
gss_buffer_t tok;
{
int ret;
ret = read_all(s, (char *) &tok->length, 4);
if (ret < 0) {
perror("reading token length");
return -1;
} else if (ret != 4) {
if (display_file)
fprintf(display_file,
"reading token length: %d of %d bytes read\n",
ret, 4);
return -1;
}
tok->length = ntohl(tok->length);
tok->value = (char *) malloc(tok->length);
if (tok->value == NULL) {
if (display_file)
fprintf(display_file,
"Out of memory allocating token data\n");
return -1;
}
ret = read_all(s, (char *) tok->value, tok->length);
if (ret < 0) {
perror("reading token data");
free(tok->value);
return -1;
} else if (ret != tok->length) {
fprintf(stderr, "sending token data: %d of %d bytes written\n",
ret, tok->length);
free(tok->value);
return -1;
}
return 0;
}
static void display_status_1(m, code, type)
char *m;
OM_uint32 code;
int type;
{
OM_uint32 maj_stat, min_stat;
gss_buffer_desc msg;
OM_uint32 msg_ctx;
msg_ctx = 0;
while (1) {
maj_stat = gss_display_status(&min_stat, code,
type, GSS_C_NULL_OID,
&msg_ctx, &msg);
if (display_file)
fprintf(display_file, "GSS-API error %s: %s\n", m,
(char *)msg.value);
(void) gss_release_buffer(&min_stat, &msg);
if (!msg_ctx)
break;
}
}
/*
* Function: display_status
*
* Purpose: displays GSS-API messages
*
* Arguments:
*
* msg a string to be displayed with the message
* maj_stat the GSS-API major status code
* min_stat the GSS-API minor status code
*
* Effects:
*
* The GSS-API messages associated with maj_stat and min_stat are
* displayed on stderr, each preceded by "GSS-API error <msg>: " and
* followed by a newline.
*/
void display_status(msg, maj_stat, min_stat)
char *msg;
OM_uint32 maj_stat;
OM_uint32 min_stat;
{
display_status_1(msg, maj_stat, GSS_C_GSS_CODE);
display_status_1(msg, min_stat, GSS_C_MECH_CODE);
}
/*
* Function: display_ctx_flags
*
* Purpose: displays the flags returned by context initiation in
* a human-readable form
*
* Arguments:
*
* int ret_flags
*
* Effects:
*
* Strings corresponding to the context flags are printed on
* stdout, preceded by "context flag: " and followed by a newline
*/
void display_ctx_flags(flags)
OM_uint32 flags;
{
if (flags & GSS_C_DELEG_FLAG)
fprintf(display_file, "context flag: GSS_C_DELEG_FLAG\n");
if (flags & GSS_C_MUTUAL_FLAG)
fprintf(display_file, "context flag: GSS_C_MUTUAL_FLAG\n");
if (flags & GSS_C_REPLAY_FLAG)
fprintf(display_file, "context flag: GSS_C_REPLAY_FLAG\n");
if (flags & GSS_C_SEQUENCE_FLAG)
fprintf(display_file, "context flag: GSS_C_SEQUENCE_FLAG\n");
if (flags & GSS_C_CONF_FLAG )
fprintf(display_file, "context flag: GSS_C_CONF_FLAG \n");
if (flags & GSS_C_INTEG_FLAG )
fprintf(display_file, "context flag: GSS_C_INTEG_FLAG \n");
}
void print_token(tok)
gss_buffer_t tok;
{
int i;
unsigned char *p = tok->value;
if (!display_file)
return;
for (i=0; i < tok->length; i++, p++) {
fprintf(display_file, "%02x ", *p);
if ((i % 16) == 15) {
fprintf(display_file, "\n");
}
}
fprintf(display_file, "\n");
fflush(display_file);
}
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