X-Git-Url: http://git.meshlink.io/?a=blobdiff_plain;f=src%2Fconf.c;h=e3574ea5442888b3fa3edee6886040264f2378c5;hb=dd2cf09a9ac438b65a1f4c9dcff8d87a2b504538;hp=75d7ebec27fdfb5b414ebb2b32ba2d252cff431f;hpb=2a7f11c0e90f5f0465bbc3c75de715454066ff72;p=meshlink

diff --git a/src/conf.c b/src/conf.c
index 75d7ebec..e3574ea5 100644
--- a/src/conf.c
+++ b/src/conf.c
@@ -1,9 +1,6 @@
 /*
     conf.c -- configuration code
-    Copyright (C) 1998 Robert van der Meulen
-                  1998-2002 Ivo Timmermans <ivo@o2w.nl>
-                  2000-2002 Guus Sliepen <guus@sliepen.eu.org>
-		  2000 Cris van Pelt <tribbel@arise.dhs.org>
+    Copyright (C) 2014 Guus Sliepen <guus@meshlink.io>
 
     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
@@ -15,574 +12,517 @@
     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., 675 Mass Ave, Cambridge, MA 02139, USA.
-
-    $Id: conf.c,v 1.9.4.64 2003/07/11 16:12:59 guus Exp $
+    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 "config.h"
-
-#include <ctype.h>
-#include <errno.h>
-#include <netdb.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <sys/stat.h>
-#include <sys/types.h>
-#include <unistd.h>
-#include <string.h>
-
-#include <xalloc.h>
-#include <utils.h>				/* for cp */
-#include <avl_tree.h>
+#include "system.h"
+#include <assert.h>
 
+#include "splay_tree.h"
+#include "connection.h"
 #include "conf.h"
-#include "netutl.h"				/* for str2address */
+#include "list.h"
 #include "logger.h"
+#include "meshlink_internal.h"
+#include "netutl.h"             /* for str2address */
+#include "protocol.h"
+#include "utils.h"              /* for cp */
+#include "xalloc.h"
 
-#include "system.h"
-
-avl_tree_t *config_tree;
-
-int pingtimeout = 0;			/* seconds before timeout */
-char *confbase = NULL;			/* directory in which all config files are */
-char *netname = NULL;			/* name of the vpn network */
-
-static int config_compare(config_t *a, config_t *b)
-{
+static int config_compare(const config_t *a, const config_t *b) {
 	int result;
 
 	result = strcasecmp(a->variable, b->variable);
 
-	if(result)
+	if(result) {
 		return result;
+	}
 
-	result = a->line - b->line;
-
-	if(result)
-		return result;
-	else
-		return strcmp(a->file, b->file);
+	return result = a->line - b->line;
 }
 
-void init_configuration(avl_tree_t ** config_tree)
-{
-	cp();
-
-	*config_tree = avl_alloc_tree((avl_compare_t) config_compare, (avl_action_t) free_config);
+void init_configuration(splay_tree_t **config_tree) {
+	*config_tree = splay_alloc_tree((splay_compare_t) config_compare, (splay_action_t) free_config);
 }
 
-void exit_configuration(avl_tree_t ** config_tree)
-{
-	cp();
+void exit_configuration(splay_tree_t **config_tree) {
+	if(*config_tree) {
+		splay_delete_tree(*config_tree);
+	}
 
-	avl_delete_tree(*config_tree);
 	*config_tree = NULL;
 }
 
-config_t *new_config(void)
-{
-	cp();
-
-	return (config_t *) xmalloc_and_zero(sizeof(config_t));
+config_t *new_config(void) {
+	return xzalloc(sizeof(config_t));
 }
 
-void free_config(config_t *cfg)
-{
-	cp();
-
-	if(cfg->variable)
-		free(cfg->variable);
-
-	if(cfg->value)
-		free(cfg->value);
-
-	if(cfg->file)
-		free(cfg->file);
-
+void free_config(config_t *cfg) {
+	free(cfg->variable);
+	free(cfg->value);
 	free(cfg);
 }
 
-void config_add(avl_tree_t *config_tree, config_t *cfg)
-{
-	cp();
-
-	avl_insert(config_tree, cfg);
+void config_add(splay_tree_t *config_tree, config_t *cfg) {
+	splay_insert(config_tree, cfg);
 }
 
-config_t *lookup_config(avl_tree_t *config_tree, char *variable)
-{
+config_t *lookup_config(splay_tree_t *config_tree, char *variable) {
 	config_t cfg, *found;
 
-	cp();
-
 	cfg.variable = variable;
-	cfg.file = "";
 	cfg.line = 0;
 
-	found = avl_search_closest_greater(config_tree, &cfg);
+	found = splay_search_closest_greater(config_tree, &cfg);
 
-	if(!found)
+	if(!found) {
 		return NULL;
+	}
 
-	if(strcasecmp(found->variable, variable))
+	if(strcasecmp(found->variable, variable)) {
 		return NULL;
+	}
 
 	return found;
 }
 
-config_t *lookup_config_next(avl_tree_t *config_tree, config_t *cfg)
-{
-	avl_node_t *node;
+config_t *lookup_config_next(splay_tree_t *config_tree, const config_t *cfg) {
+	splay_node_t *node;
 	config_t *found;
 
-	cp();
-
-	node = avl_search_node(config_tree, cfg);
+	node = splay_search_node(config_tree, cfg);
 
 	if(node) {
 		if(node->next) {
-			found = (config_t *) node->next->data;
+			found = node->next->data;
 
-			if(!strcasecmp(found->variable, cfg->variable))
+			if(!strcasecmp(found->variable, cfg->variable)) {
 				return found;
+			}
 		}
 	}
 
 	return NULL;
 }
 
-int get_config_bool(config_t *cfg, int *result)
-{
-	cp();
-
-	if(!cfg)
-		return 0;
+bool get_config_bool(const config_t *cfg, bool *result) {
+	if(!cfg) {
+		return false;
+	}
 
 	if(!strcasecmp(cfg->value, "yes")) {
-		*result = 1;
-		return 1;
+		*result = true;
+		return true;
 	} else if(!strcasecmp(cfg->value, "no")) {
-		*result = 0;
-		return 1;
+		*result = false;
+		return true;
 	}
 
-	logger(DEBUG_ALWAYS, LOG_ERR, _("\"yes\" or \"no\" expected for configuration variable %s in %s line %d"),
-		   cfg->variable, cfg->file, cfg->line);
+	logger(NULL, MESHLINK_ERROR, "\"yes\" or \"no\" expected for configuration variable %s in line %d",
+	       cfg->variable, cfg->line);
 
-	return 0;
+	return false;
 }
 
-int get_config_int(config_t *cfg, int *result)
-{
-	cp();
-
-	if(!cfg)
-		return 0;
+bool get_config_int(const config_t *cfg, int *result) {
+	if(!cfg) {
+		return false;
+	}
 
-	if(sscanf(cfg->value, "%d", result) == 1)
-		return 1;
+	if(sscanf(cfg->value, "%d", result) == 1) {
+		return true;
+	}
 
-	logger(DEBUG_ALWAYS, LOG_ERR, _("Integer expected for configuration variable %s in %s line %d"),
-		   cfg->variable, cfg->file, cfg->line);
+	logger(NULL, MESHLINK_ERROR, "Integer expected for configuration variable %s in line %d",
+	       cfg->variable, cfg->line);
 
-	return 0;
+	return false;
 }
 
-int get_config_string(config_t *cfg, char **result)
-{
-	cp();
+bool set_config_int(config_t *cfg, int val) {
+	if(!cfg) {
+		return false;
+	}
 
-	if(!cfg)
-		return 0;
+	char val_str[1024];
+	snprintf(val_str, sizeof(val_str), "%d", val);
 
-	*result = xstrdup(cfg->value);
+	if(cfg->value) {
+		free(cfg->value);
+	}
 
-	return 1;
+	cfg->value = xstrdup(val_str);
+
+	return true;
 }
 
-int get_config_address(config_t *cfg, struct addrinfo **result)
-{
-	struct addrinfo *ai;
+bool get_config_string(const config_t *cfg, char **result) {
+	if(!cfg) {
+		return false;
+	}
 
-	cp();
+	*result = xstrdup(cfg->value);
 
-	if(!cfg)
-		return 0;
+	return true;
+}
 
-	ai = str2addrinfo(cfg->value, NULL, 0);
+bool set_config_string(config_t *cfg, const char *val) {
+	if(!cfg) {
+		return false;
+	}
 
-	if(ai) {
-		*result = ai;
-		return 1;
+	if(cfg->value) {
+		free(cfg->value);
 	}
 
-	logger(DEBUG_ALWAYS, LOG_ERR, _("Hostname or IP address expected for configuration variable %s in %s line %d"),
-		   cfg->variable, cfg->file, cfg->line);
+	cfg->value = xstrdup(val);
 
-	return 0;
+	return true;
 }
 
-int get_config_subnet(config_t *cfg, subnet_t ** result)
-{
-	subnet_t *subnet;
-
-	cp();
-
-	if(!cfg)
-		return 0;
-
-	subnet = str2net(cfg->value);
+bool get_config_address(const config_t *cfg, struct addrinfo **result) {
+	struct addrinfo *ai;
 
-	if(!subnet) {
-		logger(DEBUG_ALWAYS, LOG_ERR, _("Subnet expected for configuration variable %s in %s line %d"),
-			   cfg->variable, cfg->file, cfg->line);
-		return 0;
+	if(!cfg) {
+		return false;
 	}
 
-	/* Teach newbies what subnets are... */
+	ai = str2addrinfo(cfg->value, NULL, 0);
 
-	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(DEBUG_ALWAYS, LOG_ERR, _ ("Network address and prefix length do not match for configuration variable %s in %s line %d"),
-			   cfg->variable, cfg->file, cfg->line);
-		free(subnet);
-		return 0;
+	if(ai) {
+		*result = ai;
+		return true;
 	}
 
-	*result = subnet;
+	logger(NULL, MESHLINK_ERROR, "Hostname or IP address expected for configuration variable %s in line %d",
+	       cfg->variable, cfg->line);
 
-	return 1;
+	return false;
 }
 
 /*
-  Read exactly one line and strip the trailing newline if any.  If the
-  file was on EOF, return NULL. Otherwise, return all the data in a
-  dynamically allocated buffer.
-
-  If line is non-NULL, it will be used as an initial buffer, to avoid
-  unnecessary mallocing each time this function is called.  If buf is
-  given, and buf needs to be expanded, the var pointed to by buflen
-  will be increased.
+  Read exactly one line and strip the trailing newline if any.
 */
-static char *readline(FILE * fp, char **buf, size_t *buflen)
-{
+static char *readline(FILE *fp, char *buf, size_t buflen) {
 	char *newline = NULL;
 	char *p;
-	char *line;					/* The array that contains everything that has been read so far */
-	char *idx;					/* Read into this pointer, which points to an offset within line */
-	size_t size, newsize;		/* The size of the current array pointed to by line */
-	size_t maxlen;				/* Maximum number of characters that may be read with fgets.  This is newsize - oldsize. */
 
-	if(feof(fp))
+	if(feof(fp)) {
 		return NULL;
+	}
 
-	if(buf && buflen) {
-		size = *buflen;
-		line = *buf;
-	} else {
-		size = 100;
-		line = xmalloc(size);
+	p = fgets(buf, buflen, fp);
+
+	if(!p) {
+		return NULL;
 	}
 
-	maxlen = size;
-	idx = line;
-	*idx = 0;
+	newline = strchr(p, '\n');
 
-	for(;;) {
-		errno = 0;
-		p = fgets(idx, maxlen, fp);
+	if(!newline) {
+		return buf;
+	}
 
-		if(!p) {				/* EOF or error */
-			if(feof(fp))
-				break;
+	/* kill newline and carriage return if necessary */
+	*newline = '\0';
 
-			/* otherwise: error; let the calling function print an error message if applicable */
-			free(line);
-			return NULL;
-		}
+	if(newline > p && newline[-1] == '\r') {
+		newline[-1] = '\0';
+	}
 
-		newline = strchr(p, '\n');
-
-		if(!newline) {			/* We haven't yet read everything to the end of the line */
-			newsize = size << 1;
-			line = xrealloc(line, newsize);
-			idx = &line[size - 1];
-			maxlen = newsize - size + 1;
-			size = newsize;
-		} else {
-			*newline = '\0';	/* kill newline */
-			break;				/* yay */
-		}
+	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 ");
 	}
 
-	if(buf && buflen) {
-		*buflen = size;
-		*buf = line;
+	variable[len] = '\0';
+
+	if(!*value) {
+		const char err[] = "No value for variable";
+		logger(NULL, MESHLINK_ERROR, "%s `%s' on line %d while reading config file %s",
+		       err, variable, lineno, fname);
+		return NULL;
 	}
 
-	return line;
+	cfg = new_config();
+	cfg->variable = xstrdup(variable);
+	cfg->value = xstrdup(value);
+	cfg->line = lineno;
+
+	return cfg;
 }
 
 /*
   Parse a configuration file and put the results in the configuration tree
   starting at *base.
 */
-int read_config_file(avl_tree_t *config_tree, const char *fname)
-{
-	int err = -2;				/* Parse error */
+bool read_config_file(splay_tree_t *config_tree, const char *fname) {
 	FILE *fp;
-	char *buffer, *line;
-	char *variable, *value;
-	int lineno = 0, ignore = 0;
+	char buffer[MAX_STRING_SIZE];
+	char *line;
+	int lineno = 0;
+	bool ignore = false;
 	config_t *cfg;
-	size_t bufsize;
-
-	cp();
+	bool result = false;
 
 	fp = fopen(fname, "r");
 
 	if(!fp) {
-		logger(DEBUG_ALWAYS, LOG_ERR, _("Cannot open config file %s: %s"), fname,
-			   strerror(errno));
-		return -3;
+		logger(NULL, MESHLINK_ERROR, "Cannot open config file %s: %s", fname, strerror(errno));
+		return false;
 	}
 
-	bufsize = 100;
-	buffer = xmalloc(bufsize);
-
 	for(;;) {
-		line = readline(fp, &buffer, &bufsize);
+		line = readline(fp, buffer, sizeof(buffer));
 
 		if(!line) {
-			err = -1;
+			if(feof(fp)) {
+				result = true;
+			}
+
 			break;
 		}
 
-		if(feof(fp)) {
-			err = 0;
+		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;
 		}
 
-		lineno++;
+		config_add(config_tree, cfg);
+	}
 
-		variable = strtok(line, "\t =");
+	fclose(fp);
 
-		if(!variable)
-			continue;			/* no tokens on this line */
+	return result;
+}
 
-		if(variable[0] == '#')
-			continue;			/* comment: ignore */
+bool write_config_file(const struct splay_tree_t *config_tree, const char *fname) {
+	FILE *fp;
 
-		if(!strcmp(variable, "-----BEGIN"))
-			ignore = 1;
+	fp = fopen(fname, "w+");
 
-		if(!ignore) {
-			value = strtok(NULL, "\t\n\r =");
+	if(!fp) {
+		logger(NULL, MESHLINK_ERROR, "Cannot open config file %s: %s", fname, strerror(errno));
+		return false;
+	}
 
-			if(!value || value[0] == '#') {
-				logger(DEBUG_ALWAYS, LOG_ERR, _("No value for variable `%s' on line %d while reading config file %s"),
-					   variable, lineno, fname);
-				break;
-			}
+	for splay_each(config_t, cnf, config_tree) {
+		if(fwrite(cnf->variable, sizeof(char), strlen(cnf->variable), fp) < strlen(cnf->variable)) {
+			goto error;
+		}
 
-			cfg = new_config();
-			cfg->variable = xstrdup(variable);
-			cfg->value = xstrdup(value);
-			cfg->file = xstrdup(fname);
-			cfg->line = lineno;
+		if(fwrite(" = ", sizeof(char), 3, fp) < 3) {
+			goto error;
+		}
 
-			config_add(config_tree, cfg);
+		if(fwrite(cnf->value, sizeof(char), strlen(cnf->value), fp) < strlen(cnf->value)) {
+			goto error;
 		}
 
-		if(!strcmp(variable, "-----END"))
-			ignore = 0;
+		if(fwrite("\n", sizeof(char), 1, fp) < 1) {
+			goto error;
+		}
 	}
 
-	free(buffer);
 	fclose(fp);
+	return true;
 
-	return err;
+error:
+	logger(NULL, MESHLINK_ERROR, "Cannot write to config file %s: %s", fname, strerror(errno));
+	fclose(fp);
+	return false;
 }
 
-int read_server_config()
-{
-	char *fname;
-	int x;
+bool read_server_config(meshlink_handle_t *mesh) {
+	char filename[PATH_MAX];
+	bool x;
 
-	cp();
+	snprintf(filename, PATH_MAX, "%s" SLASH "meshlink.conf", mesh->confbase);
+	errno = 0;
+	x = read_config_file(mesh->config, filename);
 
-	asprintf(&fname, "%s/tinc.conf", confbase);
-	x = read_config_file(config_tree, fname);
-
-	if(x == -1) {				/* System error: complain */
-		logger(DEBUG_ALWAYS, LOG_ERR, _("Failed to read `%s': %s"), fname, strerror(errno));
+	if(!x && errno) {
+		logger(mesh, MESHLINK_ERROR, "Failed to read `%s': %s", filename, strerror(errno));
 	}
 
-	free(fname);
-
 	return x;
 }
 
-int is_safe_path(const char *file)
-{
-	char *p;
-	const char *f;
-	char x;
-	struct stat s;
-	char l[MAXBUFSIZE];
+bool read_host_config(meshlink_handle_t *mesh, splay_tree_t *config_tree, const char *name) {
+	char filename[PATH_MAX];
+	bool x;
 
-	if(*file != '/') {
-		logger(DEBUG_ALWAYS, LOG_ERR, _("`%s' is not an absolute path"), file);
-		return 0;
-	}
+	snprintf(filename, PATH_MAX, "%s" SLASH "hosts" SLASH "%s", mesh->confbase, name);
+	x = read_config_file(config_tree, filename);
+
+	return x;
+}
 
-	p = strrchr(file, '/');
+bool write_host_config(struct meshlink_handle *mesh, const struct splay_tree_t *config_tree, const char *name) {
+	char filename[PATH_MAX];
 
-	if(p == file)				/* It's in the root */
-		p++;
+	snprintf(filename, PATH_MAX, "%s" SLASH "hosts" SLASH "%s", mesh->confbase, name);
+	return write_config_file(config_tree, filename);
+}
 
-	x = *p;
-	*p = '\0';
+bool modify_config_file(struct meshlink_handle *mesh, const char *name, const char *key, const char *value, int trim) {
+	assert(mesh && name && key);
 
-	f = file;
+	char filename[PATH_MAX];
+	char tmpname[PATH_MAX];
+	bool error = false;
 
-check1:
-	if(lstat(f, &s) < 0) {
-		logger(DEBUG_ALWAYS, LOG_ERR, _("Couldn't stat `%s': %s"), f, strerror(errno));
-		return 0;
+	if(snprintf(filename, sizeof(filename), "%s" SLASH "hosts" SLASH "%s", mesh->confbase, name) >= PATH_MAX) {
+		logger(mesh, MESHLINK_ERROR, "Filename too long: %s" SLASH "hosts" SLASH "%s", mesh->confbase, name);
+		return false;
 	}
 
-	if(s.st_uid != geteuid()) {
-		logger(DEBUG_ALWAYS, LOG_ERR, _("`%s' is owned by UID %d instead of %d"),
-			   f, s.st_uid, geteuid());
-		return 0;
+	if(snprintf(tmpname, sizeof(tmpname), "%s.tmp", filename) >= PATH_MAX) {
+		logger(mesh, MESHLINK_ERROR, "Filename too long: %s.tmp", filename);
+		return false;
 	}
 
-	if(S_ISLNK(s.st_mode)) {
-		logger(DEBUG_ALWAYS, LOG_WARNING, _("Warning: `%s' is a symlink"), f);
-
-		if(readlink(f, l, MAXBUFSIZE) < 0) {
-			logger(DEBUG_ALWAYS, LOG_ERR, _("Unable to read symbolic link `%s': %s"), f,
-				   strerror(errno));
-			return 0;
-		}
+	FILE *fr = fopen(filename, "r");
 
-		f = l;
-		goto check1;
+	if(!fr) {
+		logger(mesh, MESHLINK_ERROR, "Cannot open config file %s: %s", filename, strerror(errno));
+		return false;
 	}
 
-	*p = x;
-	f = file;
+	FILE *fw = fopen(tmpname, "w");
 
-check2:
-	if(lstat(f, &s) < 0 && errno != ENOENT) {
-		logger(DEBUG_ALWAYS, LOG_ERR, _("Couldn't stat `%s': %s"), f, strerror(errno));
-		return 0;
+	if(!fw) {
+		logger(mesh, MESHLINK_ERROR, "Cannot open temporary file %s: %s", tmpname, strerror(errno));
+		fclose(fr);
+		return false;
 	}
 
-	if(errno == ENOENT)
-		return 1;
+	char buf[4096];
+	char *sep;
+	int found = 0;
 
-	if(s.st_uid != geteuid()) {
-		logger(DEBUG_ALWAYS, LOG_ERR, _("`%s' is owned by UID %d instead of %d"),
-			   f, s.st_uid, geteuid());
-		return 0;
+	if(value) {
+		fprintf(fw, "%s = %s\n", key, value);
+		found++;
 	}
 
-	if(S_ISLNK(s.st_mode)) {
-		logger(DEBUG_ALWAYS, LOG_WARNING, _("Warning: `%s' is a symlink"), f);
-
-		if(readlink(f, l, MAXBUFSIZE) < 0) {
-			logger(DEBUG_ALWAYS, LOG_ERR, _("Unable to read symbolic link `%s': %s"), f,
-				   strerror(errno));
-			return 0;
+	while(readline(fr, buf, sizeof(buf))) {
+		if(!*buf || *buf == '#') {
+			goto copy;
 		}
 
-		f = l;
-		goto check2;
-	}
-
-	if(s.st_mode & 0007) {
-		/* Accessible by others */
-		logger(DEBUG_ALWAYS, LOG_ERR, _("`%s' has unsecure permissions"), f);
-		return 0;
-	}
+		sep = strchr(buf, ' ');
 
-	return 1;
-}
+		if(!sep) {
+			goto copy;
+		}
 
-FILE *ask_and_safe_open(const char *filename, const char *what,
-						const char *mode)
-{
-	FILE *r;
-	char *directory;
-	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 = xstrdup(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);
+		*sep = 0;
 
-		fn = readline(stdin, NULL, NULL);
+		if(strcmp(buf, key)) {
+			*sep = ' ';
+			goto copy;
+		}
 
-		if(!fn) {
-			fprintf(stderr, _("Error while reading stdin: %s\n"),
-					strerror(errno));
-			return NULL;
+		// We found the key and the value. We already added it at the top, so ignore this one.
+		if(value && sep[1] == '=' && sep[2] == ' ' && !strcmp(sep + 3, value)) {
+			continue;
 		}
 
-		if(!strlen(fn))
-			/* User just pressed enter. */
-			fn = xstrdup(filename);
-	}
+		// We found the key but with a different value, delete it if wanted.
+		found++;
+
+		if((!value || trim) && found > trim) {
+			continue;
+		}
 
-	if(!strchr(fn, '/') || fn[0] != '/') {
-		/* The directory is a relative path or a filename. */
-		char *p;
+		*sep = ' ';
 
-		directory = get_current_dir_name();
-		asprintf(&p, "%s/%s", directory, fn);
-		free(fn);
-		free(directory);
-		fn = p;
+copy:
+		fprintf(fw, "%s\n", buf);
 	}
 
-	umask(0077);				/* Disallow everything for group and other */
+	if(ferror(fr)) {
+		error = true;
+	}
 
-	/* Open it first to keep the inode busy */
+	fclose(fr);
 
-	r = fopen(fn, mode);
+	if(ferror(fw)) {
+		error = true;
+	}
 
-	if(!r) {
-		fprintf(stderr, _("Error opening file `%s': %s\n"),
-				fn, strerror(errno));
-		free(fn);
-		return NULL;
+	if(fclose(fw)) {
+		error = true;
 	}
 
-	/* Then check the file for nasty attacks */
-	if(!is_safe_path(fn)) {		/* Do not permit any directories that are readable or writeable by other users. */
-		fprintf(stderr, _("The file `%s' (or any of the leading directories) has unsafe permissions.\n"
-				 "I will not create or overwrite this file.\n"), fn);
-		fclose(r);
-		free(fn);
-		return NULL;
+	// If any error occured during reading or writing, exit.
+	if(error) {
+		unlink(tmpname);
+		return false;
 	}
 
-	free(fn);
+	// Try to atomically replace the old config file with the new one.
+#ifdef HAVE_MINGW
+	char bakname[PATH_MAX];
+	snprintf(bakname, sizeof(bakname), "%s.bak", filename);
+
+	if(rename(filename, bakname) || rename(tmpname, filename)) {
+		rename(bakname, filename);
+#else
+
+	if(rename(tmpname, filename)) {
+#endif
+		return false;
+	} else {
+#ifdef HAVE_MINGW
+		unlink(bakname);
+#endif
+		return true;
+	}
+}
 
-	return r;
+bool append_config_file(meshlink_handle_t *mesh, const char *name, const char *key, const char *value) {
+	return modify_config_file(mesh, name, key, value, 0);
 }