tinc/src/conf.c

/*
    conf.c -- configuration code
    Copyright (C) 1998 Robert van der Meulen
                  1998-2005 Ivo Timmermans
                  2000-2014 Guus Sliepen <guus@tinc-vpn.org>
                  2010-2011 Julien Muchembled <jm@jmuchemb.eu>
                  2000 Cris van Pelt

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License along
    with this program; if not, write to the Free Software Foundation, Inc.,
    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/

#include "system.h"

#include "avl_tree.h"
#include "connection.h"
#include "conf.h"
#include "list.h"
#include "logger.h"
#include "netutl.h"                             /* for str2address */
#include "protocol.h"
#include "utils.h"                              /* for cp */
#include "xalloc.h"

avl_tree_t *config_tree;

int pinginterval = 0;                   /* seconds between pings */
int pingtimeout = 0;                    /* seconds to wait for response */
char *confbase = NULL;                  /* directory in which all config files are */
char *netname = NULL;                   /* name of the vpn network */
list_t *cmdline_conf = NULL;    /* global/host configuration values given at the command line */


static int config_compare(const config_t *a, const config_t *b) {
	int result;

	result = strcasecmp(a->variable, b->variable);

	if(result) {
		return result;
	}

	/* give priority to command line options */
	result = !b->file - !a->file;

	if(result) {
		return result;
	}

	result = a->line - b->line;

	if(result) {
		return result;
	} else {
		return a->file ? strcmp(a->file, b->file) : 0;
	}
}

void init_configuration(avl_tree_t **config_tree) {
	*config_tree = avl_alloc_tree((avl_compare_t) config_compare, (avl_action_t) free_config);
}

void exit_configuration(avl_tree_t **config_tree) {
	avl_delete_tree(*config_tree);
	*config_tree = NULL;
}

config_t *new_config(void) {
	return xmalloc_and_zero(sizeof(config_t));
}

void free_config(config_t *cfg) {
	free(cfg->variable);
	free(cfg->value);
	free(cfg->file);
	free(cfg);
}

void config_add(avl_tree_t *config_tree, config_t *cfg) {
	avl_insert(config_tree, cfg);
}

config_t *lookup_config(const avl_tree_t *config_tree, char *variable) {
	config_t cfg, *found;

	cfg.variable = variable;
	cfg.file = NULL;
	cfg.line = 0;

	found = avl_search_closest_greater(config_tree, &cfg);

	if(!found) {
		return NULL;
	}

	if(strcasecmp(found->variable, variable)) {
		return NULL;
	}

	return found;
}

config_t *lookup_config_next(const avl_tree_t *config_tree, const config_t *cfg) {
	avl_node_t *node;
	config_t *found;

	node = avl_search_node(config_tree, cfg);

	if(node) {
		if(node->next) {
			found = node->next->data;

			if(!strcasecmp(found->variable, cfg->variable)) {
				return found;
			}
		}
	}

	return NULL;
}

bool get_config_bool(const config_t *cfg, bool *result) {
	if(!cfg) {
		return false;
	}

	if(!strcasecmp(cfg->value, "yes")) {
		*result = true;
		return true;
	} else if(!strcasecmp(cfg->value, "no")) {
		*result = false;
		return true;
	}

	logger(LOG_ERR, "\"yes\" or \"no\" expected for configuration variable %s in %s line %d",
	       cfg->variable, cfg->file, cfg->line);

	return false;
}

bool get_config_int(const config_t *cfg, int *result) {
	if(!cfg) {
		return false;
	}

	if(sscanf(cfg->value, "%d", result) == 1) {
		return true;
	}

	logger(LOG_ERR, "Integer expected for configuration variable %s in %s line %d",
	       cfg->variable, cfg->file, cfg->line);

	return false;
}

bool get_config_string(const config_t *cfg, char **result) {
	if(!cfg) {
		return false;
	}

	*result = xstrdup(cfg->value);

	return true;
}

bool get_config_address(const config_t *cfg, struct addrinfo **result) {
	struct addrinfo *ai;

	if(!cfg) {
		return false;
	}

	ai = str2addrinfo(cfg->value, NULL, 0);

	if(ai) {
		*result = ai;
		return true;
	}

	logger(LOG_ERR, "Hostname or IP address expected for configuration variable %s in %s line %d",
	       cfg->variable, cfg->file, cfg->line);

	return false;
}

bool get_config_subnet(const config_t *cfg, subnet_t **result) {
	subnet_t subnet = {0};

	if(!cfg) {
		return false;
	}

	if(!str2net(&subnet, cfg->value)) {
		logger(LOG_ERR, "Subnet expected for configuration variable %s in %s line %d",
		       cfg->variable, cfg->file, cfg->line);
		return false;
	}

	/* Teach newbies what subnets are... */

	if(((subnet.type == SUBNET_IPV4)
	                && !maskcheck(&subnet.net.ipv4.address, subnet.net.ipv4.prefixlength, sizeof(ipv4_t)))
	                || ((subnet.type == SUBNET_IPV6)
	                    && !maskcheck(&subnet.net.ipv6.address, subnet.net.ipv6.prefixlength, sizeof(ipv6_t)))) {
		logger(LOG_ERR, "Network address and prefix length do not match for configuration variable %s in %s line %d",
		       cfg->variable, cfg->file, cfg->line);
		return false;
	}

	*(*result = new_subnet()) = subnet;

	return true;
}

/*
  Read exactly one line and strip the trailing newline if any.
*/
static char *readline(FILE *fp, char *buf, size_t buflen) {
	char *newline = NULL;
	char *p;

	if(feof(fp)) {
		return NULL;
	}

	p = fgets(buf, buflen, fp);

	if(!p) {
		return NULL;
	}

	newline = strchr(p, '\n');

	if(!newline) {
		return buf;
	}

	*newline = '\0';        /* kill newline */

	if(newline > p && newline[-1] == '\r') { /* and carriage return if necessary */
		newline[-1] = '\0';
	}

	return buf;
}

config_t *parse_config_line(char *line, const char *fname, int lineno) {
	config_t *cfg;
	int len;
	char *variable, *value, *eol;
	variable = value = line;

	eol = line + strlen(line);

	while(strchr("\t ", *--eol)) {
		*eol = '\0';
	}

	len = strcspn(value, "\t =");
	value += len;
	value += strspn(value, "\t ");

	if(*value == '=') {
		value++;
		value += strspn(value, "\t ");
	}

	variable[len] = '\0';

	if(!*value) {
		const char err[] = "No value for variable";

		if(fname)
			logger(LOG_ERR, "%s `%s' on line %d while reading config file %s",
			       err, variable, lineno, fname);
		else
			logger(LOG_ERR, "%s `%s' in command line option %d",
			       err, variable, lineno);

		return NULL;
	}

	cfg = new_config();
	cfg->variable = xstrdup(variable);
	cfg->value = xstrdup(value);
	cfg->file = fname ? xstrdup(fname) : NULL;
	cfg->line = lineno;

	return cfg;
}

/*
  Parse a configuration file and put the results in the configuration tree
  starting at *base.
*/
bool read_config_file(avl_tree_t *config_tree, const char *fname) {
	FILE *fp;
	char buffer[MAX_STRING_SIZE];
	char *line;
	int lineno = 0;
	bool ignore = false;
	config_t *cfg;
	bool result = false;

	fp = fopen(fname, "r");

	if(!fp) {
		logger(LOG_ERR, "Cannot open config file %s: %s", fname, strerror(errno));
		return false;
	}

	for(;;) {
		line = readline(fp, buffer, sizeof(buffer));

		if(!line) {
			if(feof(fp)) {
				result = true;
			}

			break;
		}

		lineno++;

		if(!*line || *line == '#') {
			continue;
		}

		if(ignore) {
			if(!strncmp(line, "-----END", 8)) {
				ignore = false;
			}

			continue;
		}

		if(!strncmp(line, "-----BEGIN", 10)) {
			ignore = true;
			continue;
		}

		cfg = parse_config_line(line, fname, lineno);

		if(!cfg) {
			break;
		}

		config_add(config_tree, cfg);
	}

	fclose(fp);

	return result;
}

void read_config_options(avl_tree_t *config_tree, const char *prefix) {
	size_t prefix_len = prefix ? strlen(prefix) : 0;

	for(const list_node_t *node = cmdline_conf->tail; node; node = node->prev) {
		const config_t *cfg = node->data;

		if(!prefix) {
			if(strchr(cfg->variable, '.')) {
				continue;
			}
		} else {
			if(strncmp(prefix, cfg->variable, prefix_len) ||
			                cfg->variable[prefix_len] != '.') {
				continue;
			}
		}

		config_t *new = new_config();

		if(prefix) {
			new->variable = xstrdup(cfg->variable + prefix_len + 1);
		} else {
			new->variable = xstrdup(cfg->variable);
		}

		new->value = xstrdup(cfg->value);
		new->file = NULL;
		new->line = cfg->line;

		config_add(config_tree, new);
	}
}

bool read_server_config(void) {
	char fname[PATH_MAX];
	bool x;

	read_config_options(config_tree, NULL);

	snprintf(fname, sizeof(fname), "%s/tinc.conf", confbase);
	errno = 0;
	x = read_config_file(config_tree, fname);

	// We will try to read the conf files in the "conf.d" dir
	if(x) {
		char dname[PATH_MAX];
		snprintf(dname, sizeof(dname), "%s/conf.d", confbase);
		DIR *dir = opendir(dname);

		// If we can find this dir
		if(dir) {
			struct dirent *ep;

			// We list all the files in it
			while(x && (ep = readdir(dir))) {
				size_t l = strlen(ep->d_name);

				// And we try to read the ones that end with ".conf"
				if(l > 5 && !strcmp(".conf", & ep->d_name[ l - 5 ])) {
					if((size_t)snprintf(fname, sizeof(fname), "%s/%s", dname, ep->d_name) >= sizeof(fname)) {
						logger(LOG_ERR, "Pathname too long: %s/%s", dname, ep->d_name);
						return false;
					}

					x = read_config_file(config_tree, fname);
				}
			}

			closedir(dir);
		}
	}

	if(!x && errno) {
		logger(LOG_ERR, "Failed to read `%s': %s", fname, strerror(errno));
	}

	return x;
}

bool read_connection_config(connection_t *c) {
	char fname[PATH_MAX];
	bool x;

	read_config_options(c->config_tree, c->name);

	snprintf(fname, sizeof(fname), "%s/hosts/%s", confbase, c->name);
	x = read_config_file(c->config_tree, fname);

	return x;
}

static void disable_old_keys(const char *filename) {
	char tmpfile[PATH_MAX] = "";
	char buf[1024];
	bool disabled = false;
	FILE *r, *w;

	r = fopen(filename, "r");

	if(!r) {
		return;
	}

	int len = snprintf(tmpfile, sizeof(tmpfile), "%s.tmp", filename);

	if(len < 0 || len >= PATH_MAX) {
		fprintf(stderr, "Pathname too long: %s.tmp\n", filename);
		w = NULL;
	} else {
		w = fopen(tmpfile, "w");
	}

	while(fgets(buf, sizeof(buf), r)) {
		if(!strncmp(buf, "-----BEGIN RSA", 14)) {
			buf[11] = 'O';
			buf[12] = 'L';
			buf[13] = 'D';
			disabled = true;
		} else if(!strncmp(buf, "-----END RSA", 12)) {
			buf[ 9] = 'O';
			buf[10] = 'L';
			buf[11] = 'D';
			disabled = true;
		}

		if(w && fputs(buf, w) < 0) {
			disabled = false;
			break;
		}
	}

	if(w) {
		fclose(w);
	}

	fclose(r);

	if(!w && disabled) {
		fprintf(stderr, "Warning: old key(s) found, remove them by hand!\n");
		return;
	}

	if(disabled) {
#ifdef HAVE_MINGW
		// We cannot atomically replace files on Windows.
		char bakfile[PATH_MAX] = "";
		snprintf(bakfile, sizeof(bakfile), "%s.bak", filename);

		if(rename(filename, bakfile) || rename(tmpfile, filename)) {
			rename(bakfile, filename);
#else

		if(rename(tmpfile, filename)) {
#endif
			fprintf(stderr, "Warning: old key(s) found, remove them by hand!\n");
		} else  {
#ifdef HAVE_MINGW
			unlink(bakfile);
#endif
			fprintf(stderr, "Warning: old key(s) found and disabled.\n");
		}
	}

	unlink(tmpfile);
}

FILE *ask_and_open(const char *filename, const char *what) {
	FILE *r;
	char directory[PATH_MAX];
	char line[PATH_MAX];
	char abspath[PATH_MAX];
	const char *fn;

	/* Check stdin and stdout */
	if(!isatty(0) || !isatty(1)) {
		/* Argh, they are running us from a script or something.  Write
		   the files to the current directory and let them burn in hell
		   for ever. */
		fn = filename;
	} else {
		/* Ask for a file and/or directory name. */
		fprintf(stdout, "Please enter a file to save %s to [%s]: ",
		        what, filename);
		fflush(stdout);

		fn = readline(stdin, line, sizeof(line));

		if(!fn) {
			fprintf(stderr, "Error while reading stdin: %s\n",
			        strerror(errno));
			return NULL;
		}

		if(!strlen(fn))
			/* User just pressed enter. */
		{
			fn = filename;
		}
	}

#ifdef HAVE_MINGW

	if(fn[0] != '\\' && fn[0] != '/' && !strchr(fn, ':')) {
#else

	if(fn[0] != '/') {
#endif
		/* The directory is a relative path or a filename. */
		getcwd(directory, sizeof(directory));

		if((size_t)snprintf(abspath, sizeof(abspath), "%s/%s", directory, fn) >= sizeof(abspath)) {
			fprintf(stderr, "Pathname too long: %s/%s\n", directory, fn);
			return NULL;
		}

		fn = abspath;
	}

	umask(0077);                            /* Disallow everything for group and other */

	disable_old_keys(fn);

	/* Open it first to keep the inode busy */

	r = fopen(fn, "a");

	if(!r) {
		fprintf(stderr, "Error opening file `%s': %s\n",
		        fn, strerror(errno));
		return NULL;
	}

	return r;
}