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-rw-r--r--modules/pam_unix/support.c821
1 files changed, 821 insertions, 0 deletions
diff --git a/modules/pam_unix/support.c b/modules/pam_unix/support.c
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--- /dev/null
+++ b/modules/pam_unix/support.c
@@ -0,0 +1,821 @@
+/*
+ * $Id$
+ *
+ * Copyright information at end of file.
+ */
+
+#define _BSD_SOURCE
+
+#include <stdlib.h>
+#include <unistd.h>
+#include <stdarg.h>
+#include <string.h>
+#include <malloc.h>
+#include <pwd.h>
+#include <shadow.h>
+#include <limits.h>
+#include <utmp.h>
+
+#include <security/_pam_macros.h>
+#include <security/pam_modules.h>
+
+#include "md5.h"
+#include "support.h"
+
+extern char *crypt(const char *key, const char *salt);
+extern char *bigcrypt(const char *key, const char *salt);
+
+/* syslogging function for errors and other information */
+
+void _log_err(int err, const char *format,...)
+{
+ va_list args;
+
+ va_start(args, format);
+ openlog("PAM_unix", LOG_CONS | LOG_PID, LOG_AUTH);
+ vsyslog(err, format, args);
+ va_end(args);
+ closelog();
+}
+
+/* this is a front-end for module-application conversations */
+
+static int converse(pam_handle_t * pamh, int ctrl, int nargs
+ ,struct pam_message **message
+ ,struct pam_response **response)
+{
+ int retval;
+ struct pam_conv *conv;
+
+ D(("begin to converse"));
+
+ retval = pam_get_item(pamh, PAM_CONV, (const void **) &conv);
+ if (retval == PAM_SUCCESS) {
+
+ retval = conv->conv(nargs, (const struct pam_message **) message
+ ,response, conv->appdata_ptr);
+
+ D(("returned from application's conversation function"));
+
+ if (retval != PAM_SUCCESS && on(UNIX_DEBUG, ctrl)) {
+ _log_err(LOG_DEBUG, "conversation failure [%s]"
+ ,pam_strerror(pamh, retval));
+ }
+ } else if (retval != PAM_CONV_AGAIN) {
+ _log_err(LOG_ERR, "couldn't obtain coversation function [%s]"
+ ,pam_strerror(pamh, retval));
+ }
+ D(("ready to return from module conversation"));
+
+ return retval; /* propagate error status */
+}
+
+int _make_remark(pam_handle_t * pamh, unsigned int ctrl
+ ,int type, const char *text)
+{
+ int retval = PAM_SUCCESS;
+
+ if (off(UNIX__QUIET, ctrl)) {
+ struct pam_message *pmsg[1], msg[1];
+ struct pam_response *resp;
+
+ pmsg[0] = &msg[0];
+ msg[0].msg = text;
+ msg[0].msg_style = type;
+
+ resp = NULL;
+ retval = converse(pamh, ctrl, 1, pmsg, &resp);
+
+ if (resp) {
+ _pam_drop_reply(resp, 1);
+ }
+ }
+ return retval;
+}
+
+ /*
+ * Beacause getlogin() is fucked in a weird way, and
+ * sometimes it just don't work, we reimplement it here.
+ */
+char *PAM_getlogin(void)
+{
+ struct utmp *ut, line;
+ char *curr_tty, *retval;
+ static char curr_user[UT_NAMESIZE + 4];
+
+ retval = NULL;
+
+ curr_tty = ttyname(0);
+ if (curr_tty != NULL) {
+ D(("PAM_getlogin ttyname: %s", curr_tty));
+ curr_tty += 5;
+ setutent();
+ strncpy(line.ut_line, curr_tty, sizeof line.ut_line);
+ if ((ut = getutline(&line)) != NULL) {
+ strncpy(curr_user, ut->ut_user, UT_NAMESIZE);
+ retval = curr_user;
+ }
+ endutent();
+ }
+ D(("PAM_getlogin retval: %s", retval));
+
+ return retval;
+}
+
+/*
+ * set the control flags for the UNIX module.
+ */
+
+int _set_ctrl(int flags, int *remember, int argc, const char **argv)
+{
+ unsigned int ctrl;
+
+ D(("called."));
+
+ ctrl = UNIX_DEFAULTS; /* the default selection of options */
+
+ /* set some flags manually */
+
+ if (getuid() == 0 && !(flags & PAM_CHANGE_EXPIRED_AUTHTOK)) {
+ D(("IAMROOT"));
+ set(UNIX__IAMROOT, ctrl);
+ }
+ if (flags & PAM_UPDATE_AUTHTOK) {
+ D(("UPDATE_AUTHTOK"));
+ set(UNIX__UPDATE, ctrl);
+ }
+ if (flags & PAM_PRELIM_CHECK) {
+ D(("PRELIM_CHECK"));
+ set(UNIX__PRELIM, ctrl);
+ }
+ if (flags & PAM_DISALLOW_NULL_AUTHTOK) {
+ D(("DISALLOW_NULL_AUTHTOK"));
+ set(UNIX__NONULL, ctrl);
+ }
+ if (flags & PAM_SILENT) {
+ D(("SILENT"));
+ set(UNIX__QUIET, ctrl);
+ }
+ /* now parse the arguments to this module */
+
+ while (argc-- > 0) {
+ int j;
+
+ D(("pam_unix arg: %s", *argv));
+
+ for (j = 0; j < UNIX_CTRLS_; ++j) {
+ if (unix_args[j].token
+ && !strncmp(*argv, unix_args[j].token, strlen(unix_args[j].token))) {
+ break;
+ }
+ }
+
+ if (j >= UNIX_CTRLS_) {
+ _log_err(LOG_ERR, "unrecognized option [%s]", *argv);
+ } else {
+ ctrl &= unix_args[j].mask; /* for turning things off */
+ ctrl |= unix_args[j].flag; /* for turning things on */
+
+ if (remember != NULL) {
+ if (j == UNIX_REMEMBER_PASSWD) {
+ *remember = strtol(*argv + 9, NULL, 10);
+ if ((*remember == LONG_MIN) || (*remember == LONG_MAX))
+ *remember = -1;
+ if (*remember > 400)
+ *remember = 400;
+ }
+ }
+ }
+
+ ++argv; /* step to next argument */
+ }
+
+ /* auditing is a more sensitive version of debug */
+
+ if (on(UNIX_AUDIT, ctrl)) {
+ set(UNIX_DEBUG, ctrl);
+ }
+ /* return the set of flags */
+
+ D(("done."));
+ return ctrl;
+}
+
+static void _cleanup(pam_handle_t * pamh, void *x, int error_status)
+{
+ _pam_delete(x);
+}
+
+/* ************************************************************** *
+ * Useful non-trivial functions *
+ * ************************************************************** */
+
+ /*
+ * the following is used to keep track of the number of times a user fails
+ * to authenticate themself.
+ */
+
+#define FAIL_PREFIX "-UN*X-FAIL-"
+#define UNIX_MAX_RETRIES 3
+
+struct _pam_failed_auth {
+ char *user; /* user that's failed to be authenticated */
+ char *name; /* attempt from user with name */
+ int id; /* uid of name'd user */
+ int count; /* number of failures so far */
+};
+
+#ifndef PAM_DATA_REPLACE
+#error "Need to get an updated libpam 0.52 or better"
+#endif
+
+static void _cleanup_failures(pam_handle_t * pamh, void *fl, int err)
+{
+ int quiet;
+ const char *service = NULL;
+ struct _pam_failed_auth *failure;
+
+ D(("called"));
+
+ quiet = err & PAM_DATA_SILENT; /* should we log something? */
+ err &= PAM_DATA_REPLACE; /* are we just replacing data? */
+ failure = (struct _pam_failed_auth *) fl;
+
+ if (failure != NULL) {
+
+ if (!quiet && !err) { /* under advisement from Sun,may go away */
+
+ /* log the number of authentication failures */
+ if (failure->count > 1) {
+ (void) pam_get_item(pamh, PAM_SERVICE
+ ,(const void **) &service);
+ _log_err(LOG_NOTICE
+ ,"%d more authentication failure%s; %s(uid=%d) -> "
+ "%s for %s service"
+ ,failure->count - 1, failure->count == 2 ? "" : "s"
+ ,failure->name
+ ,failure->id
+ ,failure->user
+ ,service == NULL ? "**unknown**" : service
+ );
+ if (failure->count > UNIX_MAX_RETRIES) {
+ _log_err(LOG_ALERT
+ ,"service(%s) ignoring max retries; %d > %d"
+ ,service == NULL ? "**unknown**" : service
+ ,failure->count
+ ,UNIX_MAX_RETRIES);
+ }
+ }
+ }
+ _pam_delete(failure->user); /* tidy up */
+ _pam_delete(failure->name); /* tidy up */
+ free(failure);
+ }
+}
+
+/*
+ * _unix_blankpasswd() is a quick check for a blank password
+ *
+ * returns TRUE if user does not have a password
+ * - to avoid prompting for one in such cases (CG)
+ */
+
+int _unix_blankpasswd(unsigned int ctrl, const char *name)
+{
+ struct passwd *pwd = NULL;
+ struct spwd *spwdent = NULL;
+ char *salt = NULL;
+ int retval;
+
+ D(("called"));
+
+ /*
+ * This function does not have to be too smart if something goes
+ * wrong, return FALSE and let this case to be treated somewhere
+ * else (CG)
+ */
+
+ if (on(UNIX__NONULL, ctrl))
+ return 0; /* will fail but don't let on yet */
+
+ /* UNIX passwords area */
+ pwd = getpwnam(name); /* Get password file entry... */
+
+ if (pwd != NULL) {
+ if (strcmp( pwd->pw_passwd, "*NP*" ) == 0)
+ { /* NIS+ */
+ uid_t save_euid, save_uid;
+
+ save_euid = geteuid();
+ save_uid = getuid();
+ if (save_uid == pwd->pw_uid)
+ setreuid( save_euid, save_uid );
+ else {
+ setreuid( 0, -1 );
+ if (setreuid( -1, pwd->pw_uid ) == -1) {
+ setreuid( -1, 0 );
+ setreuid( 0, -1 );
+ if(setreuid( -1, pwd->pw_uid ) == -1)
+ /* Will fail elsewhere. */
+ return 0;
+ }
+ }
+
+ spwdent = getspnam( name );
+ if (save_uid == pwd->pw_uid)
+ setreuid( save_uid, save_euid );
+ else {
+ if (setreuid( -1, 0 ) == -1)
+ setreuid( save_uid, -1 );
+ setreuid( -1, save_euid );
+ }
+ } else if (strcmp(pwd->pw_passwd, "x") == 0) {
+ /*
+ * ...and shadow password file entry for this user,
+ * if shadowing is enabled
+ */
+ spwdent = getspnam(name);
+ }
+ if (spwdent)
+ salt = x_strdup(spwdent->sp_pwdp);
+ else
+ salt = x_strdup(pwd->pw_passwd);
+ }
+ /* Does this user have a password? */
+ if (salt == NULL) {
+ retval = 0;
+ } else {
+ if (strlen(salt) == 0)
+ retval = 1;
+ else
+ retval = 0;
+ }
+
+ /* tidy up */
+
+ if (salt)
+ _pam_delete(salt);
+
+ return retval;
+}
+
+/*
+ * verify the password of a user
+ */
+
+#include <sys/types.h>
+#include <sys/wait.h>
+
+static int _unix_run_helper_binary(pam_handle_t *pamh, const char *passwd, unsigned int ctrl)
+{
+ int retval, child, fds[2];
+
+ D(("called."));
+ /* create a pipe for the password */
+ if (pipe(fds) != 0) {
+ D(("could not make pipe"));
+ return PAM_AUTH_ERR;
+ }
+
+ /* fork */
+ child = fork();
+ if (child == 0) {
+ static char *args[] = { NULL, NULL };
+ static char *envp[] = { NULL };
+
+ /* XXX - should really tidy up PAM here too */
+
+ /* reopen stdin as pipe */
+ close(fds[1]);
+ dup2(fds[0], STDIN_FILENO);
+
+ /* exec binary helper */
+ args[0] = x_strdup(CHKPWD_HELPER);
+ execve(CHKPWD_HELPER, args, envp);
+
+ /* should not get here: exit with error */
+ D(("helper binary is not available"));
+ exit(PAM_AUTHINFO_UNAVAIL);
+ } else if (child > 0) {
+ /* wait for child */
+ close(fds[0]);
+ /* if the stored password is NULL */
+ if (off(UNIX__NONULL, ctrl)) { /* this means we've succeeded */
+ write(fds[1], "nullok\0\0", 8);
+ } else {
+ write(fds[1], "nonull\0\0", 8);
+ }
+ if (passwd != NULL) { /* send the password to the child */
+ write(fds[1], passwd, strlen(passwd)+1);
+ passwd = NULL;
+ } else {
+ write(fds[1], "", 1); /* blank password */
+ }
+ close(fds[1]);
+ (void) waitpid(child, &retval, 0); /* wait for helper to complete */
+ retval = (retval == 0) ? PAM_SUCCESS:PAM_AUTH_ERR;
+ } else {
+ D(("fork failed"));
+ retval = PAM_AUTH_ERR;
+ }
+
+ D(("returning %d", retval));
+ return retval;
+}
+
+int _unix_verify_password(pam_handle_t * pamh, const char *name
+ ,const char *p, unsigned int ctrl)
+{
+ struct passwd *pwd = NULL;
+ struct spwd *spwdent = NULL;
+ char *salt = NULL;
+ char *pp = NULL;
+ char *data_name;
+ int retval;
+
+ D(("called"));
+
+#ifdef HAVE_PAM_FAIL_DELAY
+ if (off(UNIX_NODELAY, ctrl)) {
+ D(("setting delay"));
+ (void) pam_fail_delay(pamh, 2000000); /* 2 sec delay for on failure */
+ }
+#endif
+
+ /* locate the entry for this user */
+
+ D(("locating user's record"));
+
+ /* UNIX passwords area */
+ pwd = getpwnam(name); /* Get password file entry... */
+
+ if (pwd != NULL) {
+ if (strcmp( pwd->pw_passwd, "*NP*" ) == 0)
+ { /* NIS+ */
+ uid_t save_euid, save_uid;
+
+ save_euid = geteuid();
+ save_uid = getuid();
+ if (save_uid == pwd->pw_uid)
+ setreuid( save_euid, save_uid );
+ else {
+ setreuid( 0, -1 );
+ if (setreuid( -1, pwd->pw_uid ) == -1) {
+ setreuid( -1, 0 );
+ setreuid( 0, -1 );
+ if(setreuid( -1, pwd->pw_uid ) == -1)
+ return PAM_CRED_INSUFFICIENT;
+ }
+ }
+
+ spwdent = getspnam( name );
+ if (save_uid == pwd->pw_uid)
+ setreuid( save_uid, save_euid );
+ else {
+ if (setreuid( -1, 0 ) == -1)
+ setreuid( save_uid, -1 );
+ setreuid( -1, save_euid );
+ }
+ } else if (strcmp(pwd->pw_passwd, "x") == 0) {
+ /*
+ * ...and shadow password file entry for this user,
+ * if shadowing is enabled
+ */
+ spwdent = getspnam(name);
+ }
+ if (spwdent)
+ salt = x_strdup(spwdent->sp_pwdp);
+ else
+ salt = x_strdup(pwd->pw_passwd);
+ }
+
+ data_name = (char *) malloc(sizeof(FAIL_PREFIX) + strlen(name));
+ if (data_name == NULL) {
+ _log_err(LOG_CRIT, "no memory for data-name");
+ } else {
+ strcpy(data_name, FAIL_PREFIX);
+ strcpy(data_name + sizeof(FAIL_PREFIX) - 1, name);
+ }
+
+ retval = PAM_SUCCESS;
+ if (pwd == NULL || salt == NULL || !strcmp(salt, "x")) {
+ if (geteuid()) {
+ /* we are not root perhaps this is the reason? Run helper */
+ D(("running helper binary"));
+ retval = _unix_run_helper_binary(pamh, p, ctrl);
+ } else {
+ D(("user's record unavailable"));
+ if (on(UNIX_AUDIT, ctrl)) {
+ /* this might be a typo and the user has given a password
+ instead of a username. Careful with this. */
+ _log_err(LOG_ALERT, "check pass; user (%s) unknown", name);
+ } else {
+ _log_err(LOG_ALERT, "check pass; user unknown");
+ }
+ p = NULL;
+ retval = PAM_AUTHINFO_UNAVAIL;
+ }
+ } else {
+ if (!strlen(salt)) {
+ /* the stored password is NULL */
+ if (off(UNIX__NONULL, ctrl)) { /* this means we've succeeded */
+ D(("user has empty password - access granted"));
+ retval = PAM_SUCCESS;
+ } else {
+ D(("user has empty password - access denied"));
+ retval = PAM_AUTH_ERR;
+ }
+ } else {
+ if (!strncmp(salt, "$1$", 3)) {
+ pp = Goodcrypt_md5(p, salt);
+ if (strcmp(pp, salt) != 0) {
+ pp = Brokencrypt_md5(p, salt);
+ }
+ } else {
+ pp = bigcrypt(p, salt);
+ }
+ p = NULL; /* no longer needed here */
+
+ /* the moment of truth -- do we agree with the password? */
+ D(("comparing state of pp[%s] and salt[%s]", pp, salt));
+
+ if (strcmp(pp, salt) == 0) {
+ retval = PAM_SUCCESS;
+ } else {
+ retval = PAM_AUTH_ERR;
+ }
+ }
+ }
+
+ if (retval == PAM_SUCCESS) {
+ if (data_name) /* reset failures */
+ pam_set_data(pamh, data_name, NULL, _cleanup_failures);
+ } else {
+ if (data_name != NULL) {
+ struct _pam_failed_auth *new = NULL;
+ const struct _pam_failed_auth *old = NULL;
+
+ /* get a failure recorder */
+
+ new = (struct _pam_failed_auth *)
+ malloc(sizeof(struct _pam_failed_auth));
+
+ if (new != NULL) {
+
+ new->user = x_strdup(name);
+ new->id = getuid();
+ new->name = x_strdup(PAM_getlogin()? PAM_getlogin() : "");
+
+ /* any previous failures for this user ? */
+ pam_get_data(pamh, data_name, (const void **) &old);
+
+ if (old != NULL) {
+ new->count = old->count + 1;
+ if (new->count >= UNIX_MAX_RETRIES) {
+ retval = PAM_MAXTRIES;
+ }
+ } else {
+ const char *service=NULL;
+ (void) pam_get_item(pamh, PAM_SERVICE,
+ (const void **)&service);
+ _log_err(LOG_NOTICE
+ ,"authentication failure; %s(uid=%d) -> "
+ "%s for %s service"
+ ,new->name
+ ,new->id
+ ,new->user
+ ,service == NULL ? "**unknown**":service
+ );
+ new->count = 1;
+ }
+
+ pam_set_data(pamh, data_name, new, _cleanup_failures);
+
+ } else {
+ _log_err(LOG_CRIT, "no memory for failure recorder");
+ }
+ }
+ }
+
+ if (data_name)
+ _pam_delete(data_name);
+ if (salt)
+ _pam_delete(salt);
+ if (pp)
+ _pam_overwrite(pp);
+
+ D(("done [%d].", retval));
+
+ return retval;
+}
+
+/*
+ * obtain a password from the user
+ */
+
+int _unix_read_password(pam_handle_t * pamh
+ ,unsigned int ctrl
+ ,const char *comment
+ ,const char *prompt1
+ ,const char *prompt2
+ ,const char *data_name
+ ,const char **pass)
+{
+ int authtok_flag;
+ int retval;
+ const char *item;
+ char *token;
+
+ D(("called"));
+
+ /*
+ * make sure nothing inappropriate gets returned
+ */
+
+ *pass = token = NULL;
+
+ /*
+ * which authentication token are we getting?
+ */
+
+ authtok_flag = on(UNIX__OLD_PASSWD, ctrl) ? PAM_OLDAUTHTOK : PAM_AUTHTOK;
+
+ /*
+ * should we obtain the password from a PAM item ?
+ */
+
+ if (on(UNIX_TRY_FIRST_PASS, ctrl) || on(UNIX_USE_FIRST_PASS, ctrl)) {
+ retval = pam_get_item(pamh, authtok_flag, (const void **) &item);
+ if (retval != PAM_SUCCESS) {
+ /* very strange. */
+ _log_err(LOG_ALERT
+ ,"pam_get_item returned error to unix-read-password"
+ );
+ return retval;
+ } else if (item != NULL) { /* we have a password! */
+ *pass = item;
+ item = NULL;
+ return PAM_SUCCESS;
+ } else if (on(UNIX_USE_FIRST_PASS, ctrl)) {
+ return PAM_AUTHTOK_RECOVER_ERR; /* didn't work */
+ } else if (on(UNIX_USE_AUTHTOK, ctrl)
+ && off(UNIX__OLD_PASSWD, ctrl)) {
+ return PAM_AUTHTOK_RECOVER_ERR;
+ }
+ }
+ /*
+ * getting here implies we will have to get the password from the
+ * user directly.
+ */
+
+ {
+ struct pam_message msg[3], *pmsg[3];
+ struct pam_response *resp;
+ int i, replies;
+
+ /* prepare to converse */
+
+ if (comment != NULL && off(UNIX__QUIET, ctrl)) {
+ pmsg[0] = &msg[0];
+ msg[0].msg_style = PAM_TEXT_INFO;
+ msg[0].msg = comment;
+ i = 1;
+ } else {
+ i = 0;
+ }
+
+ pmsg[i] = &msg[i];
+ msg[i].msg_style = PAM_PROMPT_ECHO_OFF;
+ msg[i++].msg = prompt1;
+ replies = 1;
+
+ if (prompt2 != NULL) {
+ pmsg[i] = &msg[i];
+ msg[i].msg_style = PAM_PROMPT_ECHO_OFF;
+ msg[i++].msg = prompt2;
+ ++replies;
+ }
+ /* so call the conversation expecting i responses */
+ resp = NULL;
+ retval = converse(pamh, ctrl, i, pmsg, &resp);
+
+ if (resp != NULL) {
+
+ /* interpret the response */
+
+ if (retval == PAM_SUCCESS) { /* a good conversation */
+
+ token = x_strdup(resp[i - replies].resp);
+ if (token != NULL) {
+ if (replies == 2) {
+
+ /* verify that password entered correctly */
+ if (!resp[i - 1].resp
+ || strcmp(token, resp[i - 1].resp)) {
+ _pam_delete(token); /* mistyped */
+ retval = PAM_AUTHTOK_RECOVER_ERR;
+ _make_remark(pamh, ctrl
+ ,PAM_ERROR_MSG, MISTYPED_PASS);
+ }
+ }
+ } else {
+ _log_err(LOG_NOTICE
+ ,"could not recover authentication token");
+ }
+
+ }
+ /*
+ * tidy up the conversation (resp_retcode) is ignored
+ * -- what is it for anyway? AGM
+ */
+
+ _pam_drop_reply(resp, i);
+
+ } else {
+ retval = (retval == PAM_SUCCESS)
+ ? PAM_AUTHTOK_RECOVER_ERR : retval;
+ }
+ }
+
+ if (retval != PAM_SUCCESS) {
+ if (on(UNIX_DEBUG, ctrl))
+ _log_err(LOG_DEBUG, "unable to obtain a password");
+ return retval;
+ }
+ /* 'token' is the entered password */
+
+ if (off(UNIX_NOT_SET_PASS, ctrl)) {
+
+ /* we store this password as an item */
+
+ retval = pam_set_item(pamh, authtok_flag, token);
+ _pam_delete(token); /* clean it up */
+ if (retval != PAM_SUCCESS
+ || (retval = pam_get_item(pamh, authtok_flag
+ ,(const void **) &item))
+ != PAM_SUCCESS) {
+
+ _log_err(LOG_CRIT, "error manipulating password");
+ return retval;
+
+ }
+ } else {
+ /*
+ * then store it as data specific to this module. pam_end()
+ * will arrange to clean it up.
+ */
+
+ retval = pam_set_data(pamh, data_name, (void *) token, _cleanup);
+ if (retval != PAM_SUCCESS) {
+ _log_err(LOG_CRIT, "error manipulating password data [%s]"
+ ,pam_strerror(pamh, retval));
+ _pam_delete(token);
+ return retval;
+ }
+ item = token;
+ token = NULL; /* break link to password */
+ }
+
+ *pass = item;
+ item = NULL; /* break link to password */
+
+ return PAM_SUCCESS;
+}
+
+/* ****************************************************************** *
+ * Copyright (c) Jan RÍkorajski 1999.
+ * Copyright (c) Andrew G. Morgan 1996-8.
+ * Copyright (c) Alex O. Yuriev, 1996.
+ * Copyright (c) Cristian Gafton 1996.
+ *
+ * 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, and the entire permission notice in its entirety,
+ * including the disclaimer of warranties.
+ * 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 of the author may not be used to endorse or promote
+ * products derived from this software without specific prior
+ * written permission.
+ *
+ * ALTERNATIVELY, this product may be distributed under the terms of
+ * the GNU Public License, in which case the provisions of the GPL are
+ * required INSTEAD OF the above restrictions. (This clause is
+ * necessary due to a potential bad interaction between the GPL and
+ * the restrictions contained in a BSD-style copyright.)
+ *
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
+ * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */