xref: /src/external/mpl/dhcp/dist/common/execute.c

/*	$NetBSD: execute.c,v 1.4 2022/04/03 01:10:58 christos Exp $	*/

/* execute.c

   Support for executable statements. */

/*
 * Copyright (C) 2004-2022 Internet Systems Consortium, Inc. ("ISC")
 * Copyright (c) 1998-2003 by Internet Software Consortium
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
 * ANY SPECIAL, DIRECT, 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.
 *
 *   Internet Systems Consortium, Inc.
 *   PO Box 360
 *   Newmarket, NH 03857 USA
 *   <info (at) isc.org>
 *   https://www.isc.org/
 *
 */

#include <sys/cdefs.h>
__RCSID("$NetBSD: execute.c,v 1.4 2022/04/03 01:10:58 christos Exp $");

#include "dhcpd.h"
#include <isc/util.h>
#include <omapip/omapip_p.h>
#include <sys/types.h>
#include <sys/wait.h>

int execute_statements (result, packet, lease, client_state,
			in_options, out_options, scope, statements,
			on_star)
	struct binding_value **result;
	struct packet *packet;
	struct lease *lease;
	struct client_state *client_state;
	struct option_state *in_options;
	struct option_state *out_options;
	struct binding_scope **scope;
	struct executable_statement *statements;
	struct on_star *on_star;
{
	struct executable_statement *r, *e, *next;
	int rc;
	int status;
	struct binding *binding;
	struct data_string ds;
	struct binding_scope *ns;

	if (!statements)
		return 1;

	r = NULL;
	next = NULL;
	e = NULL;
	executable_statement_reference (&r, statements, MDL);
	while (r && !(result && *result)) {
		if (r->next)
			executable_statement_reference (&next, r->next, MDL);
		switch (r->op) {
		      case statements_statement:
#if defined (DEBUG_EXPRESSIONS)
			log_debug ("exec: statements");
#endif
			status = execute_statements (result, packet, lease,
						     client_state, in_options,
						     out_options, scope,
						     r->data.statements,
						     on_star);
#if defined (DEBUG_EXPRESSIONS)
			log_debug ("exec: statements returns %d", status);
#endif
			if (!status) {
				executable_statement_dereference (&r, MDL);
				return 0;
			}
			break;

		      case on_statement:
			/*
			 * if we haven't been passed an on_star block but
			 * do have a lease, use the one from the lease
			 * This handles the previous v4 calls.
			 */
			if ((on_star == NULL) && (lease != NULL))
			    on_star = &lease->on_star;

			if (on_star != NULL) {
			    if (r->data.on.evtypes & ON_EXPIRY) {
#if defined (DEBUG_EXPRESSIONS)
				    log_debug ("exec: on expiry");
#endif
				if (on_star->on_expiry)
					executable_statement_dereference
						(&on_star->on_expiry, MDL);
				if (r->data.on.statements)
					executable_statement_reference
						(&on_star->on_expiry,
						 r->data.on.statements, MDL);
			    }
			    if (r->data.on.evtypes & ON_RELEASE) {
#if defined (DEBUG_EXPRESSIONS)
				    log_debug ("exec: on release");
#endif
				if (on_star->on_release)
					executable_statement_dereference
						(&on_star->on_release, MDL);
				if (r->data.on.statements)
					executable_statement_reference
						(&on_star->on_release,
						 r->data.on.statements, MDL);
			    }
			    if (r->data.on.evtypes & ON_COMMIT) {
#if defined (DEBUG_EXPRESSIONS)
				    log_debug ("exec: on commit");
#endif
				if (on_star->on_commit)
					executable_statement_dereference
						(&on_star->on_commit, MDL);
				if (r->data.on.statements)
					executable_statement_reference
						(&on_star->on_commit,
						 r->data.on.statements, MDL);
			    }
			}
			break;

		      case switch_statement:
#if defined (DEBUG_EXPRESSIONS)
			log_debug ("exec: switch");
#endif
			status = (find_matching_case
				  (&e, packet, lease, client_state,
				   in_options, out_options, scope,
				   r->data.s_switch.expr,
				   r->data.s_switch.statements));
#if defined (DEBUG_EXPRESSIONS)
			log_debug ("exec: switch: case %lx", (unsigned long)e);
#endif
			if (status) {
				if (!(execute_statements
				      (result, packet, lease, client_state,
				       in_options, out_options, scope, e,
				       on_star))) {
					executable_statement_dereference
						(&e, MDL);
					executable_statement_dereference
						(&r, MDL);
					return 0;
				}
				executable_statement_dereference (&e, MDL);
			}
			break;

			/* These have no effect when executed. */
		      case case_statement:
		      case default_statement:
			break;

		      case if_statement:
			status = (evaluate_boolean_expression
				  (&rc, packet,
				   lease, client_state, in_options,
				   out_options, scope, r->data.ie.expr));

#if defined (DEBUG_EXPRESSIONS)
			log_debug ("exec: if %s", (status
					      ? (rc ? "true" : "false")
					      : "NULL"));
#endif
			/* XXX Treat NULL as false */
			if (!status)
				rc = 0;
			if (!execute_statements
			    (result, packet, lease, client_state,
			     in_options, out_options, scope,
			     rc ? r->data.ie.tc : r->data.ie.fc,
			     on_star)) {
				executable_statement_dereference (&r, MDL);
				return 0;
			}
			break;

		      case eval_statement:
			status = evaluate_expression
				(NULL, packet, lease, client_state, in_options,
				 out_options, scope, r->data.eval, MDL);
#if defined (DEBUG_EXPRESSIONS)
			log_debug ("exec: evaluate: %s",
				   (status ? "succeeded" : "failed"));
#else
			POST(status);
#endif
			break;

                      case execute_statement: {
#ifdef ENABLE_EXECUTE
                        struct expression *expr;
                        char **argv;
                        int i, argc = r->data.execute.argc;
                        pid_t p;

                        /* save room for the command and the NULL terminator */
                        argv = dmalloc((argc + 2) * sizeof(*argv), MDL);
                        if (!argv)
                                break;

                        argv[0] = dmalloc(strlen(r->data.execute.command) + 1,
                                          MDL);
                        if (argv[0]) {
                                strcpy(argv[0], r->data.execute.command);
                        } else {
                                goto execute_out;
                        }

                        log_debug("execute_statement argv[0] = %s", argv[0]);

                        for (i = 1, expr = r->data.execute.arglist; expr;
                             expr = expr->data.arg.next, i++) {
                                memset (&ds, 0, sizeof(ds));
                                status = (evaluate_data_expression
                                          (&ds, packet,
                                           lease, client_state, in_options,
                                           out_options, scope,
                                           expr->data.arg.val, MDL));
                                if (status) {
                                        argv[i] = dmalloc(ds.len + 1, MDL);
                                        if (argv[i]) {
                                                memcpy(argv[i], ds.data,
                                                       ds.len);
                                                argv[i][ds.len] = 0;
                                                log_debug("execute_statement argv[%d] = %s", i, argv[i]);
                                        }
                                        data_string_forget (&ds, MDL);
                                        if (!argv[i]) {
                                                log_debug("execute_statement failed argv[%d]", i);
                                                goto execute_out;
                                        }
                                } else {
                                        log_debug("execute: bad arg %d", i);
                                        goto execute_out;
                                }
                        }
                        argv[i] = NULL;

	                if ((p = fork()) > 0) {
		        	int status;
		        	waitpid(p, &status, 0);

                        	if (status) {
                                	log_error("execute: %s exit status %d",
                                          	   argv[0], status);
                                }
	                } else if (p == 0) {
		               execvp(argv[0], argv);
		               log_error("Unable to execute %s: %m", argv[0]);
		               _exit(127);
                        } else {
                                log_error("execute: fork() failed");
                        }

                      execute_out:
                        for (i = 0; i <= argc; i++) {
                                if(argv[i])
                                	dfree(argv[i], MDL);
                        }

                        dfree(argv, MDL);
#else /* !ENABLE_EXECUTE */
		        log_fatal("Impossible case at %s:%d (ENABLE_EXECUTE "
			          "is not defined).", MDL);
#endif /* ENABLE_EXECUTE */
                        break;
                      }

		      case return_statement:
			status = evaluate_expression
				(result, packet,
				 lease, client_state, in_options,
				 out_options, scope, r -> data.retval, MDL);
#if defined (DEBUG_EXPRESSIONS)
			log_debug ("exec: return: %s",
				   (status ? "succeeded" : "failed"));
#else
			POST(status);
#endif
			break;

		      case add_statement:
#if defined (DEBUG_EXPRESSIONS)
			log_debug ("exec: add %s", (r->data.add->name
					       ? r->data.add->name
					       : "<unnamed class>"));
#endif
			libdhcp_callbacks.classify (packet, r->data.add);
			break;

		      case break_statement:
#if defined (DEBUG_EXPRESSIONS)
			log_debug ("exec: break");
#endif
			executable_statement_dereference (&r, MDL);
			return 1;

		      case supersede_option_statement:
		      case send_option_statement:
#if defined (DEBUG_EXPRESSIONS)
			log_debug ("exec: %s option %s.%s",
			      (r->op == supersede_option_statement
			       ? "supersede" : "send"),
			      r->data.option->option->universe->name,
			      r->data.option->option->name);
			goto option_statement;
#endif
		      case default_option_statement:
#if defined (DEBUG_EXPRESSIONS)
			log_debug ("exec: default option %s.%s",
			      r->data.option->option->universe->name,
			      r->data.option->option->name);
			goto option_statement;
#endif
		      case append_option_statement:
#if defined (DEBUG_EXPRESSIONS)
			log_debug ("exec: append option %s.%s",
			      r->data.option->option->universe->name,
			      r->data.option->option->name);
			goto option_statement;
#endif
		      case prepend_option_statement:
#if defined (DEBUG_EXPRESSIONS)
			log_debug ("exec: prepend option %s.%s",
			      r->data.option->option->universe->name,
			      r->data.option->option->name);
		      option_statement:
#endif
			set_option (r->data.option->option->universe,
				    out_options, r->data.option, r->op);
			break;

		      case set_statement:
		      case define_statement:
			status = 1;
			if (!scope) {
				log_error("set %s: no scope",
					   r->data.set.name);
				break;
			}
			if (!*scope) {
			    if (!binding_scope_allocate(scope, MDL)) {
				log_error("set %s: can't allocate scope",
					  r->data.set.name);
				break;
			    }
			}
			binding = find_binding(*scope, r->data.set.name);
#if defined (DEBUG_EXPRESSIONS)
			log_debug("exec: set %s", r->data.set.name);
#else
			POST(status);
#endif
			if (binding == NULL) {
				binding = dmalloc(sizeof(*binding), MDL);
				if (binding != NULL) {
				    memset(binding, 0, sizeof(*binding));
				    binding->name =
					    dmalloc(strlen
						    (r->data.set.name) + 1,
						    MDL);
				    if (binding->name != NULL) {
					strcpy(binding->name, r->data.set.name);
					binding->next = (*scope)->bindings;
					(*scope)->bindings = binding;
				    } else {
					dfree(binding, MDL);
					binding = NULL;
				    }
				}
			}
			if (binding != NULL) {
				if (binding->value != NULL)
					binding_value_dereference
						(&binding->value, MDL);
				if (r->op == set_statement) {
					status = (evaluate_expression
						  (&binding->value, packet,
						   lease, client_state,
						   in_options, out_options,
						   scope, r->data.set.expr,
						   MDL));
				} else {
				    if (!(binding_value_allocate
					  (&binding->value, MDL))) {
					    dfree(binding, MDL);
					    binding = NULL;
				    }
				    if ((binding != NULL) &&
					(binding->value != NULL)) {
					    binding->value->type =
						    binding_function;
					    (fundef_reference
					     (&binding->value->value.fundef,
					      r->data.set.expr->data.func,
					      MDL));
				    }
				}
			}
#if defined (DEBUG_EXPRESSIONS)
			log_debug ("exec: set %s%s", r -> data.set.name,
				   (binding && status ? "" : " (failed)"));
#else
			POST(status);
#endif
			break;

		      case unset_statement:
			if (!scope || !*scope)
				break;
			binding = find_binding (*scope, r->data.unset);
			if (binding) {
				if (binding->value)
					binding_value_dereference
						(&binding->value, MDL);
				status = 1;
			} else
				status = 0;
#if defined (DEBUG_EXPRESSIONS)
			log_debug ("exec: unset %s: %s", r->data.unset,
				   (status ? "found" : "not found"));
#else
			POST(status);
#endif
			break;

		      case let_statement:
#if defined (DEBUG_EXPRESSIONS)
			log_debug("exec: let %s", r->data.let.name);
#endif
			status = 0;
			ns = NULL;
			binding_scope_allocate (&ns, MDL);
			e = r;

		      next_let:
			if (ns) {
				binding = dmalloc(sizeof(*binding), MDL);
				if (!binding) {
				   blb:
				    binding_scope_dereference(&ns, MDL);
				} else {
				    memset(binding, 0, sizeof(*binding));
				    binding->name =
					    dmalloc(strlen
						    (e->data.let.name + 1),
						    MDL);
				    if (binding->name)
					strcpy(binding->name,
					       e->data.let.name);
				    else {
					dfree(binding, MDL);
					binding = NULL;
					goto blb;
				    }
				}
			} else
				binding = NULL;

			if (ns && binding) {
				status = (evaluate_expression
					  (&binding->value, packet, lease,
					   client_state,
					   in_options, out_options,
					   scope, e->data.set.expr, MDL));
				binding->next = ns->bindings;
				ns->bindings = binding;
			}

#if defined (DEBUG_EXPRESSIONS)
			log_debug("exec: let %s%s", e->data.let.name,
				  (binding && status ? "" : "failed"));
#else
			POST(status);
#endif
			if (!e->data.let.statements) {
			} else if (e->data.let.statements->op ==
				   let_statement) {
				e = e->data.let.statements;
				goto next_let;
			} else if (ns) {
				if (scope && *scope)
				    	binding_scope_reference(&ns->outer,
								*scope, MDL);
				execute_statements
				      (result, packet, lease, client_state,
				       in_options, out_options,
				       &ns, e->data.let.statements, on_star);
			}
			if (ns)
				binding_scope_dereference(&ns, MDL);
			break;

		      case log_statement:
			memset (&ds, 0, sizeof ds);
			status = (evaluate_data_expression
				  (&ds, packet,
				   lease, client_state, in_options,
				   out_options, scope, r->data.log.expr, MDL));

#if defined (DEBUG_EXPRESSIONS)
			log_debug ("exec: log");
#endif

			if (status) {
				switch (r->data.log.priority) {
				case log_priority_fatal:
					log_fatal ("%.*s", (int)ds.len,
						ds.data);
					break;
				case log_priority_error:
					log_error ("%.*s", (int)ds.len,
						ds.data);
					break;
				case log_priority_debug:
					log_debug ("%.*s", (int)ds.len,
						ds.data);
					break;
				case log_priority_info:
					log_info ("%.*s", (int)ds.len,
						ds.data);
					break;
				}
				data_string_forget (&ds, MDL);
			}

			break;

		      case vendor_opt_statement:
		        /* If possible parse any options in a vendor option
			 * encapsulation, this may add options to the in_options
			 * option state */
			parse_vendor_option(packet, lease, client_state,
					    in_options, out_options, scope);
			break;

		      default:
			log_error ("bogus statement type %d", r -> op);
			break;
		}
		executable_statement_dereference (&r, MDL);
		if (next) {
			executable_statement_reference (&r, next, MDL);
			executable_statement_dereference (&next, MDL);
		}
	}

	return 1;
}

/* Execute all the statements in a particular scope, and all statements in
   scopes outer from that scope, but if a particular limiting scope is
   reached, do not execute statements in that scope or in scopes outer
   from it.   More specific scopes need to take precedence over less
   specific scopes, so we recursively traverse the scope list, executing
   the most outer scope first. */

void execute_statements_in_scope (result, packet,
				  lease, client_state, in_options, out_options,
				  scope, group, limiting_group, on_star)
	struct binding_value **result;
	struct packet *packet;
	struct lease *lease;
	struct client_state *client_state;
	struct option_state *in_options;
	struct option_state *out_options;
	struct binding_scope **scope;
	struct group *group;
	struct group *limiting_group;
	struct on_star *on_star;
{
	struct group *limit;

	/* If we've recursed as far as we can, return. */
	if (!group)
		return;

	/* As soon as we get to a scope that is outer than the limiting
	   scope, we are done.   This is so that if somebody does something
	   like this, it does the expected thing:

	        domain-name "example.com";
		shared-network FOO {
			host bar {
				domain-name "othello.example.com";
				fixed-address 10.20.30.40;
			}
			subnet 10.20.30.0 netmask 255.255.255.0 {
				domain-name "manhattan.example.com";
			}
		}

	   The problem with the above arrangement is that the host's
	   group nesting will be host -> shared-network -> top-level,
	   and the limiting scope when we evaluate the host's scope
	   will be the subnet -> shared-network -> top-level, so we need
	   to know when we evaluate the host's scope to stop before we
	   evaluate the shared-networks scope, because it's outer than
	   the limiting scope, which means we've already evaluated it. */

	for (limit = limiting_group; limit; limit = limit -> next) {
		if (group == limit)
			return;
	}

	if (group -> next)
		execute_statements_in_scope (result, packet,
					     lease, client_state,
					     in_options, out_options, scope,
					     group->next, limiting_group,
					     on_star);
	execute_statements (result, packet, lease, client_state, in_options,
			    out_options, scope, group->statements, on_star);
}

/* Dereference or free any subexpressions of a statement being freed. */

int executable_statement_dereference (ptr, file, line)
	struct executable_statement **ptr;
	const char *file;
	int line;
{
	if (!ptr || !*ptr) {
		log_error ("%s(%d): null pointer", file, line);
#if defined (POINTER_DEBUG)
		abort ();
#else
		return 0;
#endif
	}

	(*ptr) -> refcnt--;
	rc_register (file, line, ptr, *ptr, (*ptr) -> refcnt, 1, RC_MISC);
	if ((*ptr) -> refcnt > 0) {
		*ptr = (struct executable_statement *)0;
		return 1;
	}

	if ((*ptr) -> refcnt < 0) {
		log_error ("%s(%d): negative refcnt!", file, line);
#if defined (DEBUG_RC_HISTORY)
		dump_rc_history (*ptr);
#endif
#if defined (POINTER_DEBUG)
		abort ();
#else
		return 0;
#endif
	}

	if ((*ptr) -> next)
		executable_statement_dereference (&(*ptr) -> next, file, line);

	switch ((*ptr) -> op) {
	      case statements_statement:
		if ((*ptr) -> data.statements)
			executable_statement_dereference
				(&(*ptr) -> data.statements, file, line);
		break;

	      case on_statement:
		if ((*ptr) -> data.on.statements)
			executable_statement_dereference
				(&(*ptr) -> data.on.statements, file, line);
		break;

	      case switch_statement:
		if ((*ptr) -> data.s_switch.statements)
			executable_statement_dereference
				(&(*ptr) -> data.on.statements, file, line);
		if ((*ptr) -> data.s_switch.expr)
			expression_dereference (&(*ptr) -> data.s_switch.expr,
						file, line);
		break;

	      case case_statement:
		if ((*ptr) -> data.s_switch.expr)
			expression_dereference (&(*ptr) -> data.c_case,
						file, line);
		break;

	      case if_statement:
		if ((*ptr) -> data.ie.expr)
			expression_dereference (&(*ptr) -> data.ie.expr,
						file, line);
		if ((*ptr) -> data.ie.tc)
			executable_statement_dereference
				(&(*ptr) -> data.ie.tc, file, line);
		if ((*ptr) -> data.ie.fc)
			executable_statement_dereference
				(&(*ptr) -> data.ie.fc, file, line);
		break;

	      case eval_statement:
		if ((*ptr) -> data.eval)
			expression_dereference (&(*ptr) -> data.eval,
						file, line);
		break;

	      case return_statement:
		if ((*ptr) -> data.eval)
			expression_dereference (&(*ptr) -> data.eval,
						file, line);
		break;

	      case set_statement:
		if ((*ptr)->data.set.name)
			dfree ((*ptr)->data.set.name, file, line);
		if ((*ptr)->data.set.expr)
			expression_dereference (&(*ptr) -> data.set.expr,
						file, line);
		break;

	      case unset_statement:
		if ((*ptr)->data.unset)
			dfree ((*ptr)->data.unset, file, line);
		break;

	      case execute_statement:
		if ((*ptr)->data.execute.command)
			dfree ((*ptr)->data.execute.command, file, line);
		if ((*ptr)->data.execute.arglist)
			expression_dereference (&(*ptr) -> data.execute.arglist,
						file, line);
		break;

	      case supersede_option_statement:
	      case send_option_statement:
	      case default_option_statement:
	      case append_option_statement:
	      case prepend_option_statement:
		if ((*ptr) -> data.option)
			option_cache_dereference (&(*ptr) -> data.option,
						  file, line);
		break;

	      default:
		/* Nothing to do. */
		break;
	}

	dfree ((*ptr), file, line);
	*ptr = (struct executable_statement *)0;
	return 1;
}

void write_statements (file, statements, indent)
	FILE *file;
	struct executable_statement *statements;
	int indent;
{
#if defined ENABLE_EXECUTE
	struct expression *expr;
#endif
	struct executable_statement *r, *x;
	const char *s, *t, *dot;
	int col;

	if (!statements)
		return;

	for (r = statements; r; r = r -> next) {
		switch (r -> op) {
		      case statements_statement:
			write_statements (file, r -> data.statements, indent);
			break;

		      case on_statement:
			indent_spaces (file, indent);
			fprintf (file, "on ");
			s = "";
			if (r -> data.on.evtypes & ON_EXPIRY) {
				fprintf (file, "%sexpiry", s);
				s = " or ";
			}
			if (r -> data.on.evtypes & ON_COMMIT) {
				fprintf (file, "%scommit", s);
				s = " or ";
			}
			if (r -> data.on.evtypes & ON_RELEASE) {
				fprintf (file, "%srelease", s);
				/* s = " or "; */
			}
			if (r -> data.on.statements) {
				fprintf (file, " {");
				write_statements (file,
						  r -> data.on.statements,
						  indent + 2);
				indent_spaces (file, indent);
				fprintf (file, "}");
			} else {
				fprintf (file, ";");
			}
			break;

		      case switch_statement:
			indent_spaces (file, indent);
			fprintf (file, "switch (");
			col = write_expression (file,
						r -> data.s_switch.expr,
						indent + 7, indent + 7, 1);
			col = token_print_indent (file, col, indent + 7,
						  "", "", ")");
			token_print_indent (file,
					    col, indent, " ", "", "{");
			write_statements (file, r -> data.s_switch.statements,
					  indent + 2);
			indent_spaces (file, indent);
			fprintf (file, "}");
			break;

		      case case_statement:
			indent_spaces (file, indent - 1);
			fprintf (file, "case ");
			col = write_expression (file,
						r -> data.s_switch.expr,
						indent + 5, indent + 5, 1);
			token_print_indent (file, col, indent + 5,
					    "", "", ":");
			break;

		      case default_statement:
			indent_spaces (file, indent - 1);
			fprintf (file, "default: ");
			break;

		      case if_statement:
			indent_spaces (file, indent);
			fprintf (file, "if ");
			x = r;
			col = write_expression (file,
						x -> data.ie.expr,
						indent + 3, indent + 3, 1);
		      else_if:
			token_print_indent (file, col, indent, " ", "", "{");
			write_statements (file, x -> data.ie.tc, indent + 2);
			if (x -> data.ie.fc &&
			    x -> data.ie.fc -> op == if_statement &&
			    !x -> data.ie.fc -> next) {
				indent_spaces (file, indent);
				fprintf (file, "} elsif ");
				x = x -> data.ie.fc;
				col = write_expression (file,
							x -> data.ie.expr,
							indent + 6,
							indent + 6, 1);
				goto else_if;
			}
			if (x -> data.ie.fc) {
				indent_spaces (file, indent);
				fprintf (file, "} else {");
				write_statements (file, x -> data.ie.fc,
						  indent + 2);
			}
			indent_spaces (file, indent);
			fprintf (file, "}");
			break;

		      case eval_statement:
			indent_spaces (file, indent);
			fprintf (file, "eval ");
			(void) write_expression (file, r -> data.eval,
						indent + 5, indent + 5, 1);
			fprintf (file, ";");
			break;

		      case return_statement:
			indent_spaces (file, indent);
			fprintf (file, "return;");
			break;

		      case add_statement:
			indent_spaces (file, indent);
			fprintf (file, "add \"%s\"", r -> data.add -> name);
			break;

		      case break_statement:
			indent_spaces (file, indent);
			fprintf (file, "break;");
			break;

		      case supersede_option_statement:
		      case send_option_statement:
			s = "supersede";
			goto option_statement;

		      case default_option_statement:
			s = "default";
			goto option_statement;

		      case append_option_statement:
			s = "append";
			goto option_statement;

		      case prepend_option_statement:
			s = "prepend";
		      option_statement:
			/* Note: the reason we don't try to pretty print
			   the option here is that the format of the option
			   may change in dhcpd.conf, and then when this
			   statement was read back, it would cause a syntax
			   error. */
			if (r -> data.option -> option -> universe ==
			    &dhcp_universe) {
				t = "";
				dot = "";
			} else {
				t = (r -> data.option -> option ->
				     universe -> name);
				dot = ".";
			}
			indent_spaces (file, indent);
			fprintf (file, "%s %s%s%s = ", s, t, dot,
				 r -> data.option -> option -> name);
			col = (indent + strlen (s) + strlen (t) +
			       strlen (dot) + strlen (r -> data.option ->
						      option -> name) + 4);
			if (r -> data.option -> expression)
				write_expression
					(file,
					 r -> data.option -> expression,
					 col, indent + 8, 1);
			else
				token_indent_data_string
					(file, col, indent + 8, "", "",
					 &r -> data.option -> data);

			fprintf (file, ";"); /* XXX */
			break;

		      case set_statement:
			indent_spaces (file, indent);
			fprintf (file, "set ");
			col = token_print_indent (file, indent + 4, indent + 4,
						  "", "", r -> data.set.name);
			(void) token_print_indent (file, col, indent + 4,
						  " ", " ", "=");
			col = write_expression (file, r -> data.set.expr,
						indent + 3, indent + 3, 0);
			(void) token_print_indent (file, col, indent + 4,
						  " ", "", ";");
			break;

		      case unset_statement:
			indent_spaces (file, indent);
			fprintf (file, "unset ");
			col = token_print_indent (file, indent + 6, indent + 6,
						  "", "", r -> data.set.name);
			(void) token_print_indent (file, col, indent + 6,
						  " ", "", ";");
			break;

		      case log_statement:
			indent_spaces (file, indent);
			fprintf (file, "log ");
			col = token_print_indent (file, indent + 4, indent + 4,
						  "", "", "(");
			switch (r -> data.log.priority) {
			case log_priority_fatal:
				(void) token_print_indent
					(file, col, indent + 4, "",
					 " ", "fatal,");
				break;
			case log_priority_error:
				(void) token_print_indent
					(file, col, indent + 4, "",
					 " ", "error,");
				break;
			case log_priority_debug:
				(void) token_print_indent
					(file, col, indent + 4, "",
					 " ", "debug,");
				break;
			case log_priority_info:
				(void) token_print_indent
					(file, col, indent + 4, "",
					 " ", "info,");
				break;
			}
			col = write_expression (file, r -> data.log.expr,
						indent + 4, indent + 4, 0);
			(void) token_print_indent (file, col, indent + 4,
						  "", "", ");");

			break;

                      case execute_statement:

#ifdef ENABLE_EXECUTE
			indent_spaces(file, indent);
			col = token_print_indent(file, indent + 4, indent + 4,
						 "", "", "execute");
			col = token_print_indent(file, col, indent + 4, " ", "",
						 "(");
			col = token_print_indent_concat(file, col, indent + 4,
							"", "",  "\"",
							r->data.execute.command,
							"\"", (char *)0);
			for (expr = r->data.execute.arglist; expr; expr = expr->data.arg.next) {
				col = token_print_indent(file, col, indent + 4,
							 "", " ", ",");
				col = write_expression(file, expr->data.arg.val,
						       col, indent + 4, 0);
			}
			(void) token_print_indent(file, col, indent + 4,
						  "", "", ");");
#else /* !ENABLE_EXECUTE */
		        log_fatal("Impossible case at %s:%d (ENABLE_EXECUTE "
                                  "is not defined).", MDL);
#endif /* ENABLE_EXECUTE */
                        break;

		      case vendor_opt_statement:
			indent_spaces (file, indent);
			fprintf (file, "parse-vendor-option;");
			break;

		      default:
			log_fatal ("bogus statement type %d\n", r -> op);
		}
	}
}

/* Find a case statement in the sequence of executable statements that
   matches the expression, and if found, return the following statement.
   If no case statement matches, try to find a default statement and
   return that (the default statement can precede all the case statements).
   Otherwise, return the null statement. */

int find_matching_case (struct executable_statement **ep,
			struct packet *packet, struct lease *lease,
			struct client_state *client_state,
			struct option_state *in_options,
			struct option_state *out_options,
			struct binding_scope **scope,
			struct expression *expr,
			struct executable_statement *stmt)
{
	int status, sub;
	struct executable_statement *s;

	if (is_data_expression (expr)) {
		struct data_string cd, ds;
		memset (&ds, 0, sizeof ds);
		memset (&cd, 0, sizeof cd);

		status = (evaluate_data_expression (&ds, packet, lease,
						    client_state, in_options,
						    out_options, scope, expr,
						    MDL));
		if (status) {
		    for (s = stmt; s; s = s -> next) {
			if (s -> op == case_statement) {
				sub = (evaluate_data_expression
				       (&cd, packet, lease, client_state,
					in_options, out_options,
					scope, s->data.c_case, MDL));
				if (sub && cd.len == ds.len &&
				    !memcmp (cd.data, ds.data, cd.len))
				{
					data_string_forget (&cd, MDL);
					data_string_forget (&ds, MDL);
					executable_statement_reference
						(ep, s->next, MDL);
					return 1;
				}
				data_string_forget (&cd, MDL);
			}
		    }
		    data_string_forget (&ds, MDL);
		}
	} else {
		unsigned long n, c;
		status = evaluate_numeric_expression (&n, packet, lease,
						      client_state,
						      in_options, out_options,
						      scope, expr);

		if (status) {
		    for (s = stmt; s; s = s->next) {
			if (s -> op == case_statement) {
				sub = (evaluate_numeric_expression
				       (&c, packet, lease, client_state,
					in_options, out_options,
					scope, s->data.c_case));
				if (sub && n == c) {
					executable_statement_reference
						(ep, s->next, MDL);
					return 1;
				}
			}
		    }
		}
	}

	/* If we didn't find a matching case statement, look for a default
	   statement and return the statement following it. */
	for (s = stmt; s; s = s->next)
		if (s->op == default_statement)
			break;
	if (s) {
		executable_statement_reference (ep, s->next, MDL);
		return 1;
	}
	return 0;
}

int executable_statement_foreach (struct executable_statement *stmt,
				  int (*callback) (struct
						   executable_statement *,
						   void *, int),
				  void *vp, int condp)
{
	struct executable_statement *foo;
	int ok = 0;

	for (foo = stmt; foo; foo = foo->next) {
	    if ((*callback) (foo, vp, condp) != 0)
		ok = 1;
	    switch (foo->op) {
	      case null_statement:
		break;
	      case if_statement:
		if (executable_statement_foreach (foo->data.ie.tc,
						  callback, vp, 1))
			ok = 1;
		if (executable_statement_foreach (foo->data.ie.fc,
						  callback, vp, 1))
			ok = 1;
		break;
	      case add_statement:
		break;
	      case eval_statement:
		break;
	      case break_statement:
		break;
	      case default_option_statement:
		break;
	      case supersede_option_statement:
		break;
	      case append_option_statement:
		break;
	      case prepend_option_statement:
		break;
	      case send_option_statement:
		break;
	      case statements_statement:
		if ((executable_statement_foreach
		     (foo->data.statements, callback, vp, condp)))
			ok = 1;
		break;
	      case on_statement:
		if ((executable_statement_foreach
		     (foo->data.on.statements, callback, vp, 1)))
			ok = 1;
		break;
	      case switch_statement:
		if ((executable_statement_foreach
		     (foo->data.s_switch.statements, callback, vp, 1)))
			ok = 1;
		break;
	      case case_statement:
		break;
	      case default_statement:
		break;
	      case set_statement:
		break;
	      case unset_statement:
		break;
	      case let_statement:
		if ((executable_statement_foreach
		     (foo->data.let.statements, callback, vp, 0)))
			ok = 1;
		break;
	      case define_statement:
		break;
	      case log_statement:
	      case return_statement:
	      case execute_statement:
	      case vendor_opt_statement:
		break;
	    }
	}
	return ok;
}