]> git.meshlink.io Git - meshlink/blobdiff - src/conf.c
Correctly handle incoming retransmissions of SYN packets.
[meshlink] / src / conf.c
index 740f4346b36f0f67202cf851831b42d7dd8e4d65..65ff2272ef68e50e293ad23cda5d4045315b3d7e 100644 (file)
@@ -1,9 +1,6 @@
 /*
-    conf.c -- configuration code
-    Copyright (C) 1998 Emphyrio,
-    Copyright (C) 1998,1999,2000 Ivo Timmermans <itimmermans@bigfoot.com>
-                            2000 Guus Sliepen <guus@sliepen.warande.net>
-                           2000 Cris van Pelt <tribbel@arise.dhs.org>
+    econf.c -- configuration code
+    Copyright (C) 2018 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
     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 1.9.4.13 2000/10/14 17:04:12 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 "system.h"
+#include <assert.h>
+#include <sys/types.h>
+#include <utime.h>
 
-#include <ctype.h>
-#include <errno.h>
-#include <netdb.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <syslog.h>
+#include "conf.h"
+#include "crypto.h"
+#include "logger.h"
+#include "meshlink_internal.h"
+#include "xalloc.h"
+#include "packmsg.h"
 
-#include <xalloc.h>
+/// Generate a path to the main configuration file.
+static void make_main_path(meshlink_handle_t *mesh, const char *conf_subdir, char *path, size_t len) {
+       assert(conf_subdir);
+       assert(path);
+       assert(len);
 
-#include "conf.h"
-#include "netutl.h" /* for strtoip */
-#include <utils.h> /* for cp */
+       snprintf(path, len, "%s" SLASH "%s" SLASH "meshlink.conf", mesh->confbase, conf_subdir);
+}
 
-#include "config.h"
-#include "connlist.h"
-#include "system.h"
+/// Generate a path to a host configuration file.
+static void make_host_path(meshlink_handle_t *mesh, const char *conf_subdir, const char *name, char *path, size_t len) {
+       assert(conf_subdir);
+       assert(name);
+       assert(path);
+       assert(len);
 
-config_t *config;
-int debug_lvl = 0;
-int timeout = 0; /* seconds before timeout */
-char *confbase = NULL;           /* directory in which all config files are */
+       snprintf(path, len, "%s" SLASH "%s" SLASH "hosts" SLASH "%s", mesh->confbase, conf_subdir, name);
+}
 
-/* Will be set if HUP signal is received. It will be processed when it is safe. */
-int sighup = 0;
+/// Generate a path to an unused invitation file.
+static void make_invitation_path(meshlink_handle_t *mesh, const char *conf_subdir, const char *name, char *path, size_t len) {
+       assert(conf_subdir);
+       assert(name);
+       assert(path);
+       assert(len);
 
-/*
-  These are all the possible configurable values
-*/
-static internal_config_t hazahaza[] = {
-/* Main configuration file keywords */
-  { "Name",         tincname,       TYPE_NAME },
-  { "ConnectTo",    connectto,      TYPE_NAME },
-  { "PingTimeout",  pingtimeout,    TYPE_INT },
-  { "TapDevice",    tapdevice,      TYPE_NAME },
-  { "PrivateKey",   privatekey,     TYPE_NAME },
-  { "KeyExpire",    keyexpire,      TYPE_INT },
-  { "Hostnames",    resolve_dns,    TYPE_BOOL },
-  { "Interface",    interface,      TYPE_NAME },
-  { "InterfaceIP",  interfaceip,    TYPE_IP },
-/* Host configuration file keywords */
-  { "Address",      address,        TYPE_NAME },
-  { "Port",         port,           TYPE_INT },
-  { "PublicKey",    publickey,      TYPE_NAME },
-  { "Subnet",       subnet,         TYPE_NAME },
-  { "RestrictHosts", restricthosts, TYPE_BOOL },
-  { "RestrictSubnets", restrictsubnets, TYPE_BOOL },
-  { "RestrictAddress", restrictaddress, TYPE_BOOL },
-  { "RestrictPort", restrictport,   TYPE_BOOL },
-  { "IndirectData", indirectdata,   TYPE_BOOL },
-  { "TCPonly",      tcponly,        TYPE_BOOL },
-  { NULL, 0, 0 }
-};
+       snprintf(path, len, "%s" SLASH "%s" SLASH "invitations" SLASH "%s", mesh->confbase, conf_subdir, name);
+}
 
-/*
-  Add given value to the list of configs cfg
-*/
-config_t *
-add_config_val(config_t **cfg, int argtype, char *val)
-{
-  config_t *p, *r;
-  char *q;
-cp
-  p = (config_t*)xmalloc(sizeof(*p));
-  p->data.val = 0;
-  
-  switch(argtype)
-    {
-    case TYPE_INT:
-      p->data.val = strtol(val, &q, 0);
-      if(q && *q)
-       p->data.val = 0;
-      break;
-    case TYPE_NAME:
-      p->data.ptr = xmalloc(strlen(val) + 1);
-      strcpy(p->data.ptr, val);
-      break;
-    case TYPE_IP:
-      p->data.ip = strtoip(val);
-      break;
-    case TYPE_BOOL:
-      if(!strcasecmp("yes", val))
-       p->data.val = stupid_true;
-      else if(!strcasecmp("no", val))
-       p->data.val = stupid_false;
-      else
-       p->data.val = 0;
-    }
-
-  p->argtype = argtype;
-
-  if(p->data.val)
-    {
-      if(*cfg)
-        {
-          r = *cfg;
-          while(r->next)
-            r = r->next;
-          r->next = p;
-        }
-      else
-        *cfg = p;
-      p->next = NULL;
-      return p;
-    }
-
-  free(p);
-cp
-  return NULL;
+/// Generate a path to a used invitation file.
+static void make_used_invitation_path(meshlink_handle_t *mesh, const char *conf_subdir, const char *name, char *path, size_t len) {
+       assert(conf_subdir);
+       assert(name);
+       assert(path);
+       assert(len);
+
+       snprintf(path, len, "%s" SLASH "%s" SLASH "invitations" SLASH "%s.used", mesh->confbase, conf_subdir, name);
 }
 
-/*
-  Parse a configuration file and put the results in the configuration tree
-  starting at *base.
-*/
-int read_config_file(config_t **base, const char *fname)
-{
-  int err = -1;
-  FILE *fp;
-  char line[MAXBUFSIZE];       /* There really should not be any line longer than this... */
-  char *p, *q;
-  int i, lineno = 0;
-  config_t *cfg;
-cp
-  if((fp = fopen (fname, "r")) == NULL)
-    {
-      return -1;
-    }
-
-  for(;;)
-    {
-      if(fgets(line, MAXBUFSIZE, fp) == NULL)
-        {
-          err = 0;
-          break;
-        }
-        
-      lineno++;
-
-      if(!index(line, '\n'))
-        {
-          syslog(LOG_ERR, _("Line %d too long while reading config file %s"), lineno, fname);
-          break;
-        }        
-
-      if((p = strtok(line, "\t\n\r =")) == NULL)
-       continue; /* no tokens on this line */
-
-      if(p[0] == '#')
-       continue; /* comment: ignore */
-
-      for(i = 0; hazahaza[i].name != NULL; i++)
-       if(!strcasecmp(hazahaza[i].name, p))
-         break;
-
-      if(!hazahaza[i].name)
-       {
-         syslog(LOG_ERR, _("Invalid variable name on line %d while reading config file %s"),
-                 lineno, fname);
-          break;
-       }
-
-      if(((q = strtok(NULL, "\t\n\r =")) == NULL) || q[0] == '#')
-       {
-         fprintf(stderr, _("No value for variable on line %d while reading config file %s"),
-                 lineno, fname);
-         break;
-       }
-
-      cfg = add_config_val(base, hazahaza[i].argtype, q);
-      if(cfg == NULL)
-       {
-         fprintf(stderr, _("Invalid value for variable on line %d while reading config file %s"),
-                 lineno, fname);
-         break;
-       }
-
-      cfg->which = hazahaza[i].which;
-      if(!config)
-       config = cfg;
-    }
-
-  fclose (fp);
-cp
-  return err;
+/// Remove a directory recursively
+static void deltree(const char *dirname) {
+       assert(dirname);
+
+       DIR *d = opendir(dirname);
+
+       if(d) {
+               struct dirent *ent;
+
+               while((ent = readdir(d))) {
+                       if(ent->d_name[0] == '.') {
+                               continue;
+                       }
+
+                       char filename[PATH_MAX];
+                       snprintf(filename, sizeof(filename), "%s" SLASH "%s", dirname, ent->d_name);
+
+                       if(unlink(filename)) {
+                               deltree(filename);
+                       }
+               }
+
+               closedir(d);
+       }
+
+       rmdir(dirname);
 }
 
-int read_server_config()
-{
-  char *fname;
-  int x;
-cp
-  asprintf(fname, "%s/tinc.conf", confbase);
-  x = read_config_file(&config, fname);
-  free(fname);
-cp
-  return x;  
+static bool sync_path(const char *pathname) {
+       assert(pathname);
+
+       int fd = open(pathname, O_RDONLY);
+
+       if(fd < 0) {
+               logger(NULL, MESHLINK_ERROR, "Failed to open %s: %s\n", pathname, strerror(errno));
+               meshlink_errno = MESHLINK_ESTORAGE;
+               return false;
+       }
+
+       if(fsync(fd)) {
+               logger(NULL, MESHLINK_ERROR, "Failed to sync %s: %s\n", pathname, strerror(errno));
+               close(fd);
+               meshlink_errno = MESHLINK_ESTORAGE;
+               return false;
+       }
+
+       if(close(fd)) {
+               logger(NULL, MESHLINK_ERROR, "Failed to close %s: %s\n", pathname, strerror(errno));
+               close(fd);
+               meshlink_errno = MESHLINK_ESTORAGE;
+               return false;
+       }
+
+       return true;
 }
 
-/*
-  Look up the value of the config option type
-*/
-const config_t *get_config_val(config_t *p, which_t type)
-{
-cp
-  for(p = config; p != NULL; p = p->next)
-    if(p->which == type)
-      return p;
-cp
-  /* Not found */
-  return NULL;
+/// Try decrypting the main configuration file from the given sub-directory.
+static bool main_config_decrypt(meshlink_handle_t *mesh, const char *conf_subdir) {
+       assert(mesh->config_key);
+       assert(mesh->confbase);
+       assert(conf_subdir);
+
+       config_t config;
+
+       if(!main_config_read(mesh, conf_subdir, &config, mesh->config_key)) {
+               logger(mesh, MESHLINK_ERROR, "Could not read main configuration file");
+               return false;
+       }
+
+       packmsg_input_t in = {config.buf, config.len};
+
+       uint32_t version = packmsg_get_uint32(&in);
+       config_free(&config);
+
+       return version == MESHLINK_CONFIG_VERSION;
 }
 
-/*
-  Support for multiple config lines.
-  Index is used to get a specific value, 0 being the first, 1 the second etc.
-*/
-const config_t *get_next_config_val(config_t *p, which_t type, int index)
-{
-cp  
-  for(p = config; p != NULL; p = p->next)
-    if(p->which == type)
-      if(--index < 0)
-        return p;
-cp  
-  /* Not found */
-  return NULL;
+/// Create a fresh configuration directory
+bool config_init(meshlink_handle_t *mesh, const char *conf_subdir) {
+       assert(conf_subdir);
+
+       if(!mesh->confbase) {
+               return true;
+       }
+
+       if(mkdir(mesh->confbase, 0700) && errno != EEXIST) {
+               logger(mesh, MESHLINK_DEBUG, "Could not create directory %s: %s\n", mesh->confbase, strerror(errno));
+               return false;
+       }
+
+       char path[PATH_MAX];
+
+       // Create "current" sub-directory in the confbase
+       snprintf(path, sizeof(path), "%s" SLASH "%s", mesh->confbase, conf_subdir);
+       deltree(path);
+
+       if(mkdir(path, 0700)) {
+               logger(mesh, MESHLINK_DEBUG, "Could not create directory %s: %s\n", path, strerror(errno));
+               return false;
+       }
+
+       make_host_path(mesh, conf_subdir, "", path, sizeof(path));
+
+       if(mkdir(path, 0700)) {
+               logger(mesh, MESHLINK_DEBUG, "Could not create directory %s: %s\n", path, strerror(errno));
+               return false;
+       }
+
+       make_invitation_path(mesh, conf_subdir, "", path, sizeof(path));
+
+       if(mkdir(path, 0700)) {
+               logger(mesh, MESHLINK_DEBUG, "Could not create directory %s: %s\n", path, strerror(errno));
+               return false;
+       }
+
+       return true;
 }
 
-/*
-  Remove the complete configuration tree.
-*/
-void clear_config(config_t **base)
-{
-  config_t *p, *next;
-cp
-  for(p = *base; p != NULL; p = next)
-    {
-      next = p->next;
-      if(p->data.ptr && (p->argtype == TYPE_NAME))
-        {
-          free(p->data.ptr);
-        }
-      free(p);
-    }
-  *base = NULL;
-cp
+/// Wipe an existing configuration directory
+bool config_destroy(const char *confbase, const char *conf_subdir) {
+       assert(conf_subdir);
+
+       if(!confbase) {
+               return false;
+       }
+
+       struct stat st;
+
+       char path[PATH_MAX];
+
+       // Check the presence of configuration base sub directory.
+       snprintf(path, sizeof(path), "%s" SLASH "%s", confbase, conf_subdir);
+
+       if(stat(path, &st)) {
+               if(errno == ENOENT) {
+                       return true;
+               } else {
+                       logger(NULL, MESHLINK_ERROR, "Cannot stat %s: %s\n", path, strerror(errno));
+                       meshlink_errno = MESHLINK_ESTORAGE;
+                       return false;
+               }
+       }
+
+       // Remove meshlink.conf
+       snprintf(path, sizeof(path), "%s" SLASH "%s" SLASH "meshlink.conf", confbase, conf_subdir);
+
+       if(unlink(path)) {
+               if(errno != ENOENT) {
+                       logger(NULL, MESHLINK_ERROR, "Cannot delete %s: %s\n", path, strerror(errno));
+                       meshlink_errno = MESHLINK_ESTORAGE;
+                       return false;
+               }
+       }
+
+       snprintf(path, sizeof(path), "%s" SLASH "%s", confbase, conf_subdir);
+       deltree(path);
+       return true;
+}
+
+static bool copytree(const char *src_dir_name, const void *src_key, const char *dst_dir_name, const void *dst_key) {
+       assert(src_dir_name);
+       assert(dst_dir_name);
+
+       char src_filename[PATH_MAX];
+       char dst_filename[PATH_MAX];
+       struct dirent *ent;
+
+       DIR *src_dir = opendir(src_dir_name);
+
+       if(!src_dir) {
+               logger(NULL, MESHLINK_ERROR, "Could not open directory file %s\n", src_dir_name);
+               return false;
+       }
+
+       // Delete if already exists and create a new destination directory
+       deltree(dst_dir_name);
+
+       if(mkdir(dst_dir_name, 0700)) {
+               logger(NULL, MESHLINK_ERROR, "Could not create directory %s\n", dst_filename);
+               return false;
+       }
+
+       while((ent = readdir(src_dir))) {
+               if(ent->d_name[0] == '.') {
+                       continue;
+               }
+
+               snprintf(dst_filename, sizeof(dst_filename), "%s" SLASH "%s", dst_dir_name, ent->d_name);
+               snprintf(src_filename, sizeof(src_filename), "%s" SLASH "%s", src_dir_name, ent->d_name);
+
+               if(ent->d_type == DT_DIR) {
+                       if(!copytree(src_filename, src_key, dst_filename, dst_key)) {
+                               logger(NULL, MESHLINK_ERROR, "Copying %s to %s failed\n", src_filename, dst_filename);
+                               return false;
+                       }
+
+                       if(!sync_path(dst_filename)) {
+                               return false;
+                       }
+               } else if(ent->d_type == DT_REG) {
+                       struct stat st;
+                       config_t config;
+
+                       if(stat(src_filename, &st)) {
+                               logger(NULL, MESHLINK_ERROR, "Could not stat file `%s': %s\n", src_filename, strerror(errno));
+                               return false;
+                       }
+
+                       FILE *f = fopen(src_filename, "r");
+
+                       if(!f) {
+                               logger(NULL, MESHLINK_ERROR, "Failed to open `%s': %s\n", src_filename, strerror(errno));
+                               return false;
+                       }
+
+                       if(!config_read_file(NULL, f, &config, src_key)) {
+                               logger(NULL, MESHLINK_ERROR, "Failed to read `%s': %s\n", src_filename, strerror(errno));
+                               fclose(f);
+                               return false;
+                       }
+
+                       if(fclose(f)) {
+                               logger(NULL, MESHLINK_ERROR, "Failed to close `%s': %s\n", src_filename, strerror(errno));
+                               config_free(&config);
+                               return false;
+                       }
+
+                       f = fopen(dst_filename, "w");
+
+                       if(!f) {
+                               logger(NULL, MESHLINK_ERROR, "Failed to open `%s': %s", dst_filename, strerror(errno));
+                               config_free(&config);
+                               return false;
+                       }
+
+                       if(!config_write_file(NULL, f, &config, dst_key)) {
+                               logger(NULL, MESHLINK_ERROR, "Failed to write `%s': %s", dst_filename, strerror(errno));
+                               config_free(&config);
+                               fclose(f);
+                               return false;
+                       }
+
+                       if(fclose(f)) {
+                               logger(NULL, MESHLINK_ERROR, "Failed to close `%s': %s", dst_filename, strerror(errno));
+                               config_free(&config);
+                               return false;
+                       }
+
+                       config_free(&config);
+
+                       struct utimbuf times;
+                       times.modtime = st.st_mtime;
+                       times.actime = st.st_atime;
+
+                       if(utime(dst_filename, &times)) {
+                               logger(NULL, MESHLINK_ERROR, "Failed to utime `%s': %s", dst_filename, strerror(errno));
+                               return false;
+                       }
+               }
+       }
+
+       closedir(src_dir);
+       return true;
+}
+
+bool config_copy(meshlink_handle_t *mesh, const char *src_dir_name, const void *src_key, const char *dst_dir_name, const void *dst_key) {
+       assert(src_dir_name);
+       assert(dst_dir_name);
+
+       char src_filename[PATH_MAX];
+       char dst_filename[PATH_MAX];
+
+       snprintf(dst_filename, sizeof(dst_filename), "%s" SLASH "%s", mesh->confbase, dst_dir_name);
+       snprintf(src_filename, sizeof(src_filename), "%s" SLASH "%s", mesh->confbase, src_dir_name);
+
+       return copytree(src_filename, src_key, dst_filename, dst_key);
+}
+
+/// Check the presence of the main configuration file.
+bool main_config_exists(meshlink_handle_t *mesh, const char *conf_subdir) {
+       assert(conf_subdir);
+
+       if(!mesh->confbase) {
+               return false;
+       }
+
+       char path[PATH_MAX];
+       make_main_path(mesh, conf_subdir, path, sizeof(path));
+       return access(path, F_OK) == 0;
+}
+
+bool config_rename(meshlink_handle_t *mesh, const char *old_conf_subdir, const char *new_conf_subdir) {
+       assert(old_conf_subdir);
+       assert(new_conf_subdir);
+
+       if(!mesh->confbase) {
+               return false;
+       }
+
+       char old_path[PATH_MAX];
+       char new_path[PATH_MAX];
+
+       snprintf(old_path, sizeof(old_path), "%s" SLASH "%s", mesh->confbase, old_conf_subdir);
+       snprintf(new_path, sizeof(new_path), "%s" SLASH "%s", mesh->confbase, new_conf_subdir);
+
+       return rename(old_path, new_path) == 0;
+}
+
+bool config_sync(meshlink_handle_t *mesh, const char *conf_subdir) {
+       assert(conf_subdir);
+
+       if(!mesh->confbase) {
+               return true;
+       }
+
+       char path[PATH_MAX];
+       snprintf(path, sizeof(path), "%s" SLASH "%s" SLASH "hosts", mesh->confbase, conf_subdir);
+
+       if(!sync_path(path)) {
+               return false;
+       }
+
+       snprintf(path, sizeof(path), "%s" SLASH "%s", mesh->confbase, conf_subdir);
+
+       if(!sync_path(path)) {
+               return false;
+       }
+
+       return true;
+}
+
+bool meshlink_confbase_exists(meshlink_handle_t *mesh) {
+       if(!mesh->confbase) {
+               return false;
+       }
+
+       bool confbase_exists = false;
+       bool confbase_decryptable = false;
+
+       if(main_config_exists(mesh, "current")) {
+               confbase_exists = true;
+
+               if(mesh->config_key && main_config_decrypt(mesh, "current")) {
+                       confbase_decryptable = true;
+               }
+       }
+
+       if(mesh->config_key && !confbase_decryptable && main_config_exists(mesh, "new")) {
+               confbase_exists = true;
+
+               if(main_config_decrypt(mesh, "new")) {
+                       if(!config_destroy(mesh->confbase, "current")) {
+                               return false;
+                       }
+
+                       if(!config_rename(mesh, "new", "current")) {
+                               return false;
+                       }
+
+                       confbase_decryptable = true;
+               }
+       }
+
+       if(mesh->config_key && !confbase_decryptable && main_config_exists(mesh, "old")) {
+               confbase_exists = true;
+
+               if(main_config_decrypt(mesh, "old")) {
+                       if(!config_destroy(mesh->confbase, "current")) {
+                               return false;
+                       }
+
+                       if(!config_rename(mesh, "old", "current")) {
+                               return false;
+                       }
+
+                       confbase_decryptable = true;
+               }
+       }
+
+       // Cleanup if current is existing with old and new
+       if(confbase_exists && confbase_decryptable) {
+               config_destroy(mesh->confbase, "old");
+               config_destroy(mesh->confbase, "new");
+       }
+
+       return confbase_exists;
+}
+
+/// Lock the main configuration file.
+bool main_config_lock(meshlink_handle_t *mesh) {
+       if(!mesh->confbase) {
+               return true;
+       }
+
+       char path[PATH_MAX];
+       make_main_path(mesh, "current", path, sizeof(path));
+
+       mesh->conffile = fopen(path, "r");
+
+       if(!mesh->conffile) {
+               logger(NULL, MESHLINK_ERROR, "Cannot not open %s: %s\n", path, strerror(errno));
+               meshlink_errno = MESHLINK_ESTORAGE;
+               return false;
+       }
+
+#ifdef FD_CLOEXEC
+       fcntl(fileno(mesh->conffile), F_SETFD, FD_CLOEXEC);
+#endif
+
+#ifdef HAVE_MINGW
+       // TODO: use _locking()?
+#else
+
+       if(flock(fileno(mesh->conffile), LOCK_EX | LOCK_NB) != 0) {
+               logger(NULL, MESHLINK_ERROR, "Cannot lock %s: %s\n", path, strerror(errno));
+               fclose(mesh->conffile);
+               mesh->conffile = NULL;
+               meshlink_errno = MESHLINK_EBUSY;
+               return false;
+       }
+
+#endif
+
+       return true;
+}
+
+/// Unlock the main configuration file.
+void main_config_unlock(meshlink_handle_t *mesh) {
+       if(mesh->conffile) {
+               fclose(mesh->conffile);
+               mesh->conffile = NULL;
+       }
+}
+
+/// Read a configuration file from a FILE handle.
+bool config_read_file(meshlink_handle_t *mesh, FILE *f, config_t *config, const void *key) {
+       assert(f);
+
+       long len;
+
+       if(fseek(f, 0, SEEK_END) || !(len = ftell(f)) || fseek(f, 0, SEEK_SET)) {
+               logger(mesh, MESHLINK_ERROR, "Cannot get config file size: %s\n", strerror(errno));
+               meshlink_errno = MESHLINK_ESTORAGE;
+               return false;
+       }
+
+       uint8_t *buf = xmalloc(len);
+
+       if(fread(buf, len, 1, f) != 1) {
+               logger(mesh, MESHLINK_ERROR, "Cannot read config file: %s\n", strerror(errno));
+               meshlink_errno = MESHLINK_ESTORAGE;
+               return false;
+       }
+
+       if(key) {
+               uint8_t *decrypted = xmalloc(len);
+               size_t decrypted_len = len;
+               chacha_poly1305_ctx_t *ctx = chacha_poly1305_init();
+               chacha_poly1305_set_key(ctx, key);
+
+               if(len > 12 && chacha_poly1305_decrypt_iv96(ctx, buf, buf + 12, len - 12, decrypted, &decrypted_len)) {
+                       chacha_poly1305_exit(ctx);
+                       free(buf);
+                       config->buf = decrypted;
+                       config->len = decrypted_len;
+                       return true;
+               } else {
+                       logger(mesh, MESHLINK_ERROR, "Cannot decrypt config file\n");
+                       meshlink_errno = MESHLINK_ESTORAGE;
+                       chacha_poly1305_exit(ctx);
+                       free(decrypted);
+                       free(buf);
+                       return false;
+               }
+       }
+
+       config->buf = buf;
+       config->len = len;
+
+       return true;
+}
+
+/// Write a configuration file to a FILE handle.
+bool config_write_file(meshlink_handle_t *mesh, FILE *f, const config_t *config, const void *key) {
+       assert(f);
+
+       if(key) {
+               uint8_t buf[config->len + 16];
+               size_t len = sizeof(buf);
+               uint8_t seqbuf[12];
+               randomize(&seqbuf, sizeof(seqbuf));
+               chacha_poly1305_ctx_t *ctx = chacha_poly1305_init();
+               chacha_poly1305_set_key(ctx, key);
+               bool success = false;
+
+               if(chacha_poly1305_encrypt_iv96(ctx, seqbuf, config->buf, config->len, buf, &len)) {
+                       success = fwrite(seqbuf, sizeof(seqbuf), 1, f) == 1 && fwrite(buf, len, 1, f) == 1;
+               } else {
+                       logger(mesh, MESHLINK_ERROR, "Cannot encrypt config file\n");
+                       meshlink_errno = MESHLINK_ESTORAGE;
+               }
+
+               chacha_poly1305_exit(ctx);
+               return success;
+       }
+
+       if(fwrite(config->buf, config->len, 1, f) != 1) {
+               logger(mesh, MESHLINK_ERROR, "Cannot write config file: %s", strerror(errno));
+               meshlink_errno = MESHLINK_ESTORAGE;
+               return false;
+       }
+
+       if(fsync(fileno(f))) {
+               logger(mesh, MESHLINK_ERROR, "Failed to sync file: %s\n", strerror(errno));
+               return false;
+       }
+
+       return true;
+}
+
+/// Free resources of a loaded configuration file.
+void config_free(config_t *config) {
+       assert(!config->len || config->buf);
+
+       free((uint8_t *)config->buf);
+       config->buf = NULL;
+       config->len = 0;
+}
+
+/// Check the presence of a host configuration file.
+bool config_exists(meshlink_handle_t *mesh, const char *conf_subdir, const char *name) {
+       assert(conf_subdir);
+
+       if(!mesh->confbase) {
+               return false;
+       }
+
+       char path[PATH_MAX];
+       make_host_path(mesh, conf_subdir, name, path, sizeof(path));
+
+       return access(path, F_OK) == 0;
+}
+
+/// Read a host configuration file.
+bool config_read(meshlink_handle_t *mesh, const char *conf_subdir, const char *name, config_t *config, void *key) {
+       assert(conf_subdir);
+
+       if(!mesh->confbase) {
+               return false;
+       }
+
+       char path[PATH_MAX];
+       make_host_path(mesh, conf_subdir, name, path, sizeof(path));
+
+       FILE *f = fopen(path, "r");
+
+       if(!f) {
+               logger(mesh, MESHLINK_ERROR, "Failed to open `%s': %s", path, strerror(errno));
+               return false;
+       }
+
+       if(!config_read_file(mesh, f, config, key)) {
+               logger(mesh, MESHLINK_ERROR, "Failed to read `%s': %s", path, strerror(errno));
+               fclose(f);
+               return false;
+       }
+
+       fclose(f);
+
+       return true;
+}
+
+bool config_scan_all(meshlink_handle_t *mesh, const char *conf_subdir, const char *conf_type, config_scan_action_t action, void *arg) {
+       assert(conf_subdir);
+       assert(conf_type);
+
+       if(!mesh->confbase) {
+               return true;
+       }
+
+       DIR *dir;
+       struct dirent *ent;
+       char dname[PATH_MAX];
+       snprintf(dname, sizeof(dname), "%s" SLASH "%s" SLASH "%s", mesh->confbase, conf_subdir, conf_type);
+
+       dir = opendir(dname);
+
+       if(!dir) {
+               logger(mesh, MESHLINK_ERROR, "Could not open %s: %s", dname, strerror(errno));
+               meshlink_errno = MESHLINK_ESTORAGE;
+               return false;
+       }
+
+       while((ent = readdir(dir))) {
+               if(ent->d_name[0] == '.') {
+                       continue;
+               }
+
+               if(!action(mesh, ent->d_name, arg)) {
+                       closedir(dir);
+                       return false;
+               }
+       }
+
+       closedir(dir);
+       return true;
+}
+
+/// Write a host configuration file.
+bool config_write(meshlink_handle_t *mesh, const char *conf_subdir, const char *name, const config_t *config, void *key) {
+       assert(conf_subdir);
+       assert(name);
+       assert(config);
+
+       if(!mesh->confbase) {
+               return true;
+       }
+
+       char path[PATH_MAX];
+       char tmp_path[PATH_MAX + 4];
+       make_host_path(mesh, conf_subdir, name, path, sizeof(path));
+       snprintf(tmp_path, sizeof(tmp_path), "%s.tmp", path);
+
+       FILE *f = fopen(tmp_path, "w");
+
+       if(!f) {
+               logger(mesh, MESHLINK_ERROR, "Failed to open `%s': %s", tmp_path, strerror(errno));
+               return false;
+       }
+
+       if(!config_write_file(mesh, f, config, key)) {
+               logger(mesh, MESHLINK_ERROR, "Failed to write `%s': %s", tmp_path, strerror(errno));
+               fclose(f);
+               return false;
+       }
+
+       if(fsync(fileno(f))) {
+               logger(mesh, MESHLINK_ERROR, "Failed to sync `%s': %s", tmp_path, strerror(errno));
+               fclose(f);
+               return false;
+       }
+
+       if(fclose(f)) {
+               logger(mesh, MESHLINK_ERROR, "Failed to close `%s': %s", tmp_path, strerror(errno));
+               return false;
+       }
+
+       if(rename(tmp_path, path)) {
+               logger(mesh, MESHLINK_ERROR, "Failed to rename `%s' to `%s': %s", tmp_path, path, strerror(errno));
+               return false;
+       }
+
+       return true;
+}
+
+/// Read the main configuration file.
+bool main_config_read(meshlink_handle_t *mesh, const char *conf_subdir, config_t *config, void *key) {
+       assert(conf_subdir);
+       assert(config);
+
+       if(!mesh->confbase) {
+               return false;
+       }
+
+       char path[PATH_MAX];
+       make_main_path(mesh, conf_subdir, path, sizeof(path));
+
+       FILE *f = fopen(path, "r");
+
+       if(!f) {
+               logger(mesh, MESHLINK_ERROR, "Failed to open `%s': %s", path, strerror(errno));
+               return false;
+       }
+
+       if(!config_read_file(mesh, f, config, key)) {
+               logger(mesh, MESHLINK_ERROR, "Failed to read `%s': %s", path, strerror(errno));
+               fclose(f);
+               return false;
+       }
+
+       fclose(f);
+
+       return true;
+}
+
+/// Write the main configuration file.
+bool main_config_write(meshlink_handle_t *mesh, const char *conf_subdir, const config_t *config, void *key) {
+       assert(conf_subdir);
+       assert(config);
+
+       if(!mesh->confbase) {
+               return true;
+       }
+
+       char path[PATH_MAX];
+       char tmp_path[PATH_MAX + 4];
+       make_main_path(mesh, conf_subdir, path, sizeof(path));
+       snprintf(tmp_path, sizeof(tmp_path), "%s.tmp", path);
+
+       FILE *f = fopen(tmp_path, "w");
+
+       if(!f) {
+               logger(mesh, MESHLINK_ERROR, "Failed to open `%s': %s", tmp_path, strerror(errno));
+               return false;
+       }
+
+       if(!config_write_file(mesh, f, config, key)) {
+               logger(mesh, MESHLINK_ERROR, "Failed to write `%s': %s", tmp_path, strerror(errno));
+               fclose(f);
+               return false;
+       }
+
+       if(fsync(fileno(f))) {
+               logger(mesh, MESHLINK_ERROR, "Failed to sync `%s': %s", tmp_path, strerror(errno));
+               fclose(f);
+               return false;
+       }
+
+       if(rename(tmp_path, path)) {
+               logger(mesh, MESHLINK_ERROR, "Failed to rename `%s' to `%s': %s", tmp_path, path, strerror(errno));
+               fclose(f);
+               return false;
+       }
+
+       if(fclose(f)) {
+               logger(mesh, MESHLINK_ERROR, "Failed to close `%s': %s", tmp_path, strerror(errno));
+               return false;
+       }
+
+       return true;
+}
+
+/// Read an invitation file from the confbase sub-directory, and immediately delete it.
+bool invitation_read(meshlink_handle_t *mesh, const char *conf_subdir, const char *name, config_t *config, void *key) {
+       assert(conf_subdir);
+       assert(name);
+       assert(config);
+
+       if(!mesh->confbase) {
+               return false;
+       }
+
+       char path[PATH_MAX];
+       char used_path[PATH_MAX];
+       make_invitation_path(mesh, conf_subdir, name, path, sizeof(path));
+       make_used_invitation_path(mesh, conf_subdir, name, used_path, sizeof(used_path));
+
+       // Atomically rename the invitation file
+       if(rename(path, used_path)) {
+               if(errno == ENOENT) {
+                       logger(mesh, MESHLINK_ERROR, "Peer tried to use non-existing invitation %s\n", name);
+               } else {
+                       logger(mesh, MESHLINK_ERROR, "Error trying to rename invitation %s\n", name);
+               }
+
+               return false;
+       }
+
+       FILE *f = fopen(used_path, "r");
+
+       if(!f) {
+               logger(mesh, MESHLINK_ERROR, "Failed to open `%s': %s", path, strerror(errno));
+               return false;
+       }
+
+       // Check the timestamp
+       struct stat st;
+
+       if(fstat(fileno(f), &st)) {
+               logger(mesh, MESHLINK_ERROR, "Could not stat invitation file %s\n", name);
+               fclose(f);
+               unlink(used_path);
+               return false;
+       }
+
+       if(mesh->loop.now.tv_sec > st.st_mtime + mesh->invitation_timeout) {
+               logger(mesh, MESHLINK_ERROR, "Peer tried to use an outdated invitation file %s\n", name);
+               fclose(f);
+               unlink(used_path);
+               return false;
+       }
+
+       if(!config_read_file(mesh, f, config, key)) {
+               logger(mesh, MESHLINK_ERROR, "Failed to read `%s': %s", path, strerror(errno));
+               fclose(f);
+               unlink(used_path);
+               return false;
+       }
+
+       fclose(f);
+
+       unlink(used_path);
+       return true;
+}
+
+/// Write an invitation file.
+bool invitation_write(meshlink_handle_t *mesh, const char *conf_subdir, const char *name, const config_t *config, void *key) {
+       assert(conf_subdir);
+       assert(name);
+       assert(config);
+
+       if(!mesh->confbase) {
+               return false;
+       }
+
+       char path[PATH_MAX];
+       make_invitation_path(mesh, conf_subdir, name, path, sizeof(path));
+
+       FILE *f = fopen(path, "w");
+
+       if(!f) {
+               logger(mesh, MESHLINK_ERROR, "Failed to open `%s': %s", path, strerror(errno));
+               return false;
+       }
+
+       if(!config_write_file(mesh, f, config, key)) {
+               logger(mesh, MESHLINK_ERROR, "Failed to write `%s': %s", path, strerror(errno));
+               fclose(f);
+               return false;
+       }
+
+       if(fsync(fileno(f))) {
+               logger(mesh, MESHLINK_ERROR, "Failed to sync `%s': %s", path, strerror(errno));
+               fclose(f);
+               return false;
+       }
+
+       if(fclose(f)) {
+               logger(mesh, MESHLINK_ERROR, "Failed to close `%s': %s", path, strerror(errno));
+               return false;
+       }
+
+       return true;
+}
+
+/// Purge old invitation files
+size_t invitation_purge_old(meshlink_handle_t *mesh, time_t deadline) {
+       if(!mesh->confbase) {
+               return true;
+       }
+
+       char path[PATH_MAX];
+       make_invitation_path(mesh, "current", "", path, sizeof(path));
+
+       DIR *dir = opendir(path);
+
+       if(!dir) {
+               logger(mesh, MESHLINK_DEBUG, "Could not read directory %s: %s\n", path, strerror(errno));
+               meshlink_errno = MESHLINK_ESTORAGE;
+               return 0;
+       }
+
+       errno = 0;
+       size_t count = 0;
+       struct dirent *ent;
+
+       while((ent = readdir(dir))) {
+               if(strlen(ent->d_name) != 24) {
+                       continue;
+               }
+
+               char invname[PATH_MAX];
+               struct stat st;
+
+               if(snprintf(invname, sizeof(invname), "%s" SLASH "%s", path, ent->d_name) >= PATH_MAX) {
+                       logger(mesh, MESHLINK_DEBUG, "Filename too long: %s" SLASH "%s", path, ent->d_name);
+                       continue;
+               }
+
+               if(!stat(invname, &st)) {
+                       if(mesh->invitation_key && deadline < st.st_mtime) {
+                               count++;
+                       } else {
+                               unlink(invname);
+                       }
+               } else {
+                       logger(mesh, MESHLINK_DEBUG, "Could not stat %s: %s\n", invname, strerror(errno));
+                       errno = 0;
+               }
+       }
+
+       if(errno) {
+               logger(mesh, MESHLINK_DEBUG, "Error while reading directory %s: %s\n", path, strerror(errno));
+               closedir(dir);
+               meshlink_errno = MESHLINK_ESTORAGE;
+               return 0;
+       }
+
+       closedir(dir);
+
+       return count;
 }