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7 munge_encode, munge_decode, munge_strerror - MUNGE core functions
8
11 #include <munge.h>
12 munge_err_t munge_encode (char **cred, munge_ctx_t ctx,
14 const void *buf, int len);
15 munge_err_t munge_decode (const char *cred, munge_ctx_t ctx,
17 void **buf, int *len, uid_t *uid, gid_t *gid);
18 const char * munge_strerror (munge_err_t e);
20 cc `pkg-config --cflags --libs munge` -o foo foo.c
22
25 The munge_encode() function creates a credential contained in a NUL-
26 terminated base64 string. A payload specified by a buffer buf of
27 length len can be encapsulated in as well. If the MUNGE context ctx is
28 NULL, the default context will be used. A pointer to the resulting
29 credential is returned via cred; on error, it is set to NULL. The
30 caller is responsible for freeing the memory referenced by cred.
31 The munge_decode() function validates the NUL-terminated credential
33 cred. If the MUNGE context ctx is not NULL, it will be set to that
34 used to encode the credential. If buf and len are not NULL, memory
35 will be allocated for the encapsulated payload, buf will be set to
36 point to this data, and len will be set to its length. An additional
37 NUL character will be appended to this payload data but not included in
38 its length. If no payload exists, buf will be set to NULL and len will
39 be set to 0. For certain errors (i.e., EMUNGE_CRED_EXPIRED, EMU‐
40 NGE_CRED_REWOUND, EMUNGE_CRED_REPLAYED), payload memory will still be
41 allocated if necessary. The caller is responsible for freeing the mem‐
42 ory referenced by buf. If uid or gid is not NULL, they will be set to
43 the UID/GID of the process that created the credential.
44 The munge_strerror() function returns a descriptive text string
46 describing the MUNGE error number e.
47
50 The munge_encode() and munge_decode() functions return EMUNGE_SUCCESS
51 on success, or a MUNGE error otherwise. If a MUNGE context was used,
52 it may contain a more detailed error message accessible via
53 munge_ctx_strerror().
54 The munge_strerror() function returns a pointer to a NUL-terminated
56 constant text string; this string should not be freed or modified by
57 the caller.
58
61 EMUNGE_SUCCESS
62 Success.
63 EMUNGE_SNAFU
65 Internal error.
66 EMUNGE_BAD_ARG
68 Invalid argument.
69 EMUNGE_BAD_LENGTH
71 Exceeded the maximum message length as specified by the munged
72 configuration.
73 EMUNGE_OVERFLOW
75 Exceeded the maximum length of a buffer.
76 EMUNGE_NO_MEMORY
78 Unable to allocate the requisite memory.
79 EMUNGE_SOCKET
81 Unable to communicate with the daemon on the domain socket.
82 EMUNGE_BAD_CRED
84 The credential does not match the specified format.
85 EMUNGE_BAD_VERSION
87 The credential contains an unsupported version number.
88 EMUNGE_BAD_CIPHER
90 The credential contains an unsupported cipher type.
91 EMUNGE_BAD_MAC
93 The credential contains an unsupported MAC type.
94 EMUNGE_BAD_ZIP
96 The credential contains an unsupported compression type.
97 EMUNGE_BAD_REALM
99 The credential contains an unrecognized security realm.
100 EMUNGE_CRED_INVALID
102 The credential is invalid. This means the credential could not
103 be successfully decoded. More than likely, the secret keys on
104 the encoding and decoding hosts do not match. Another possibil‐
105 ity is that the credential has been altered since it was
106 encoded.
107 EMUNGE_CRED_EXPIRED
109 The credential has expired. This means more than TTL seconds
110 have elapsed since the credential was encoded. Another possi‐
111 bility is that the clocks on the encoding and decoding hosts are
112 out of sync.
113 EMUNGE_CRED_REWOUND
115 The credential appears to have been encoded at some point in the
116 future. This means the clock on the decoding host is slower
117 than that of the encoding host by more than the allowable clock
118 skew. More than likely, the clocks on the encoding and decoding
119 hosts are out of sync.
120 EMUNGE_CRED_REPLAYED
122 The credential has been previously decoded on this host.
123 EMUNGE_CRED_UNAUTHORIZED
125 The client is not authorized to decode the credential based upon
126 the effective user and/or group ID of the process.
127
130 The following example program illustrates the use of a MUNGE credential
131 to ascertain the effective user and group ID of the encoding process.
132 #include <stdio.h> /* for printf() */
134 #include <stdlib.h> /* for exit() & free() */
135 #include <unistd.h> /* for uid_t & gid_t */
136 #include <munge.h>
137 int
139 main (int argc, char *argv[])
140 {
141 char *cred;
142 munge_err_t err;
143 uid_t uid;
144 gid_t gid;
145 err = munge_encode (&cred, NULL, NULL, 0);
147 if (err != EMUNGE_SUCCESS) {
149 fprintf (stderr, "ERROR: %s\n", munge_strerror (err));
150 exit (1);
151 }
152 err = munge_decode (cred, NULL, NULL, NULL, &uid, &gid);
153 if (err != EMUNGE_SUCCESS) {
155 fprintf (stderr, "ERROR: %s\n", munge_strerror (err));
156 exit (1);
157 }
158 printf ("uid=%d gid=%d\n", uid, gid);
159 free (cred);
160 exit (0);
161 }
162
165 Both munge_encode() and munge_decode() may allocate memory that the
166 caller is responsible for freeing. Failure to do so will result in a
167 memory leak.
168
171 Chris Dunlap <cdunlap@llnl.gov>
172
175 Copyright (C) 2007-2017 Lawrence Livermore National Security, LLC.
176 Copyright (C) 2002-2007 The Regents of the University of California.
177 MUNGE is free software: you can redistribute it and/or modify it under
179 the terms of the GNU General Public License as published by the Free
180 Software Foundation, either version 3 of the License, or (at your
181 option) any later version.
182 Additionally for the MUNGE library (libmunge), you can redistribute it
184 and/or modify it under the terms of the GNU Lesser General Public
185 License as published by the Free Software Foundation, either version 3
186 of the License, or (at your option) any later version.
187
190 munge(1), remunge(1), unmunge(1), munge_ctx(3), munge_enum(3),
191 munge(7), munged(8).
192 https://dun.github.io/munge/
194munge-0.5.13 2017-09-26 MUNGE(3)