lurch.c 92.2 KB
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#include <glib.h>

#include <inttypes.h>
#include <string.h>
#include <time.h>

#include "account.h"
#include "cmds.h"
#include "conversation.h"
#include "debug.h"
#include "notify.h"
#include "plugin.h"
#include "util.h"
#include "version.h"
#include "xmlnode.h"

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#include "jabber.h"
#include "jutil.h"
#include "pep.h"
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#include "libomemo.h"
#include "libomemo_crypto.h"
#include "libomemo_storage.h"
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#include "axc.h"
#include "axc_store.h"
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#include "lurch.h"

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#ifdef _WIN32
#define strnlen(a, b) (MIN(strlen(a), (b)))
#endif

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#define JABBER_PROTOCOL_ID "prpl-jabber"

// see https://www.ietf.org/rfc/rfc3920.txt
#define JABBER_MAX_LEN_NODE 1023
#define JABBER_MAX_LEN_DOMAIN 1023
#define JABBER_MAX_LEN_BARE JABBER_MAX_LEN_NODE + JABBER_MAX_LEN_DOMAIN + 1

#define LURCH_ACC_SETTING_INITIALIZED "lurch_initialised"

#define LURCH_DB_SUFFIX "_db.sqlite"
#define LURCH_DB_NAME_OMEMO "omemo"
#define LURCH_DB_NAME_AXC "axc"

#define LURCH_ERR           -1000000
#define LURCH_ERR_NOMEM     -1000001
#define LURCH_ERR_NO_BUNDLE -1000010

#define LURCH_ERR_STRING_ENCRYPT "There was an error encrypting the message and it was not sent. " \
                                 "You can try again, or try to find the problem by looking at the debug log."
#define LURCH_ERR_STRING_DECRYPT "There was an error decrypting an OMEMO message addressed to this device. " \
                                 "See the debug log for details."
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typedef struct lurch_addr {
  char * jid;
  uint32_t device_id;
} lurch_addr;
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typedef struct lurch_queued_msg {
  omemo_message * om_msg_p;
  GList * recipient_addr_l_p;
  GList * no_sess_l_p;
  GHashTable * sess_handled_p;
} lurch_queued_msg;

omemo_crypto_provider crypto = {
    .random_bytes_func = omemo_default_crypto_random_bytes,
    .aes_gcm_encrypt_func = omemo_default_crypto_aes_gcm_encrypt,
    .aes_gcm_decrypt_func = omemo_default_crypto_aes_gcm_decrypt
};

int topic_changed = 0;
int uninstall = 0;

PurpleCmdId lurch_cmd_id = 0;

// key: char * (name of muc), value: GHashTable * (mapping of user alias to full jid)
GHashTable * chat_users_ht_p = (void *) 0;

static void lurch_addr_list_destroy_func(gpointer data) {
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  lurch_addr * addr_p = (lurch_addr *) data;
  free(addr_p->jid);
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  free(addr_p);
}

/**
 * Creates a queued msg.
 * Note that it just saves the pointers, so make sure they are not freed during
 * the lifetime of this struct and instead use the destroy function when done.
 *
 * @param om_msg_p Pointer to the omemo_message.
 * @param recipient_addr_l_p Pointer to the list of recipient addresses.
 * @param no_sess_l_p Pointer to the list that contains the addresses that do
 *                    not have sessions, i.e. for which bundles were requested.
 * @param cmsg_pp Will point to the pointer of the created queued msg struct.
 * @return 0 on success, negative on error.
 */
static int lurch_queued_msg_create(omemo_message * om_msg_p,
                                   GList * recipient_addr_l_p,
                                   GList * no_sess_l_p,
                                   lurch_queued_msg ** qmsg_pp) {
  int ret_val = 0;
  char * err_msg_dbg = (void *) 0;

  lurch_queued_msg * qmsg_p = (void *) 0;
  GHashTable * sess_handled_p = (void *) 0;

  qmsg_p = malloc(sizeof(lurch_queued_msg));
  if (!qmsg_p) {
    ret_val = LURCH_ERR_NOMEM;
    err_msg_dbg = g_strdup_printf("failed to malloc space for queued msg struct");
    goto cleanup;
  }

  sess_handled_p = g_hash_table_new(g_str_hash, g_str_equal);

  qmsg_p->om_msg_p = om_msg_p;
  qmsg_p->recipient_addr_l_p = recipient_addr_l_p;
  qmsg_p->no_sess_l_p = no_sess_l_p;
  qmsg_p->sess_handled_p = sess_handled_p;

  *qmsg_pp = qmsg_p;

cleanup:
  if (ret_val) {
    free(qmsg_p);
  }
  if (err_msg_dbg) {
    purple_debug_error("lurch", "%s: %s (%i)\n", __func__, err_msg_dbg, ret_val);
    free(err_msg_dbg);
  }
  return ret_val;
}

static int lurch_queued_msg_is_handled(const lurch_queued_msg * qmsg_p) {
  return (g_list_length(qmsg_p->no_sess_l_p) == g_hash_table_size(qmsg_p->sess_handled_p)) ? 1 : 0;
}

/**
 * Frees all the memory used by the queued msg.
 */
static void lurch_queued_msg_destroy(lurch_queued_msg * qmsg_p) {
  if (qmsg_p) {
    omemo_message_destroy(qmsg_p->om_msg_p);
    g_list_free_full(qmsg_p->recipient_addr_l_p, free);
    g_hash_table_destroy(qmsg_p->sess_handled_p);
    free(qmsg_p);
  }
}

static char * lurch_queue_make_key_string_s(const char * name, const char * device_id) {
  return g_strconcat(name, "/", device_id, NULL);
}

/**
 * Returns the db name, has to be g_free()d.
 *
 * @param uname The username.
 * @param which Either LURCH_DB_NAME_OMEMO or LURCH_DB_NAME_AXC
 * @return The path string.
 */
static char * lurch_uname_get_db_fn(const char * uname, char * which) {
  return g_strconcat(purple_user_dir(), "/", uname, "_", which, LURCH_DB_SUFFIX, NULL);
}

/**
 * For some reason pidgin returns account names with a trailing "/".
 * This function removes it.
 * All other functions asking for the username assume the "/" is already stripped.
 *
 * @param uname The username.
 * @return A duplicated string with the trailing "/" removed. free() when done.
 */
static char * lurch_uname_strip(const char * uname) {
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  char ** split;
  char * stripped;

  split = g_strsplit(uname, "/", 2);
  stripped = g_strdup(split[0]);

  g_strfreev(split);

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  return stripped;
}

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/**
 * Log wrapper for AXC
 *
 * @param level	an AXC_LOG level
 * @param msg 	the log message
 * @param len	the length of the message
 * @param ctx_p	the axc context
 */
static void lurch_axc_log_func(int level, const char * msg, size_t len, void * user_data)
{
  switch(level) {
    case AXC_LOG_ERROR:
      purple_debug_error("lurch", "[AXC ERROR] %s", msg);
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      break;
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    case AXC_LOG_WARNING:
      purple_debug_warning("lurch", "[AXC WARNING] %s", msg);
      break;
    case AXC_LOG_NOTICE:
      purple_debug_info("lurch", "[AXC NOTICE] %s", msg);
      break;
    case AXC_LOG_INFO:
      purple_debug_info("lurch", "[AXC INFO] %s", msg);
      break;
    case AXC_LOG_DEBUG:
      purple_debug_misc("lurch", "[AXC DEBUG] %s", msg);
      break;
    default:
      purple_debug_misc("lurch", "[AXC %d] %s", level, msg);
      break;
  }
}

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/**
 * Creates and initializes the axc context.
 *
 * @param uname The username.
 * @param ctx_pp Will point to an initialized axc context on success.
 * @return 0 on success, negative on error.
 */
static int lurch_axc_get_init_ctx(char * uname, axc_context ** ctx_pp) {
  int ret_val = 0;
  char * err_msg_dbg = (void *) 0;

  axc_context * ctx_p = (void *) 0;
  char * db_fn = (void *) 0;

  ret_val = axc_context_create(&ctx_p);
  if (ret_val) {
    err_msg_dbg = g_strdup_printf("failed to create axc context");
    goto cleanup;
  }

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  axc_context_set_log_func(ctx_p, lurch_axc_log_func);

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  db_fn = lurch_uname_get_db_fn(uname, LURCH_DB_NAME_AXC);
  ret_val = axc_context_set_db_fn(ctx_p, db_fn, strlen(db_fn));
  if (ret_val) {
    err_msg_dbg = g_strdup_printf("failed to set axc db filename");
    goto cleanup;
  }

  ret_val = axc_init(ctx_p);
  if (ret_val) {
    err_msg_dbg = g_strdup_printf("failed to init axc context");
    goto cleanup;
  }

  *ctx_pp = ctx_p;

cleanup:
  if (ret_val) {
    axc_context_destroy_all(ctx_p);
  }
  if (err_msg_dbg) {
    purple_debug_error("lurch", "%s: %s (%i)\n", __func__, err_msg_dbg, ret_val);
    free(err_msg_dbg);
  }

  free (db_fn);
  return ret_val;
}

/**
 * Does the first-time install of the axc DB.
 * As specified in OMEMO, it checks if the generated device ID already exists.
 * Therefore, it should be called at a point in time when other entries exist.
 *
 * @param uname The username.
 * @return 0 on success, negative on error.
 */
static int lurch_axc_prepare(char * uname) {
  int ret_val = 0;
  char * err_msg_dbg = (void *) 0;

  axc_context * axc_ctx_p = (void *) 0;
  uint32_t device_id = 0;
  char * db_fn_omemo = (void *) 0;

  ret_val = lurch_axc_get_init_ctx(uname, &axc_ctx_p);
  if (ret_val) {
    err_msg_dbg = g_strdup_printf("failed to get init axc ctx");
    goto cleanup;
  }

  ret_val = axc_get_device_id(axc_ctx_p, &device_id);
  if (!ret_val) {
    // already installed
    goto cleanup;
  }

  db_fn_omemo = lurch_uname_get_db_fn(uname, LURCH_DB_NAME_OMEMO);

  while (1) {
    ret_val = axc_install(axc_ctx_p);
    if (ret_val) {
      err_msg_dbg = g_strdup_printf("failed to install axc");
      goto cleanup;
    }

    ret_val = axc_get_device_id(axc_ctx_p, &device_id);
    if (ret_val) {
      err_msg_dbg = g_strdup_printf("failed to get own device id");
      goto cleanup;
    }

    ret_val = omemo_storage_global_device_id_exists(device_id, db_fn_omemo);
    if (ret_val == 1)  {
      ret_val = axc_db_init_status_set(AXC_DB_NEEDS_ROLLBACK, axc_ctx_p);
      if (ret_val) {
        err_msg_dbg = g_strdup_printf("failed to set axc db to rollback");
        goto cleanup;
      }
    } else if (ret_val < 0) {
      err_msg_dbg = g_strdup_printf("failed to access the db %s", db_fn_omemo);
      goto cleanup;
    } else {
      break;
    }
  }

cleanup:
  if (err_msg_dbg) {
    purple_debug_error("lurch", "%s: %s (%i)\n", __func__, err_msg_dbg, ret_val);
    free(err_msg_dbg);
  }
  axc_context_destroy_all(axc_ctx_p);
  free(db_fn_omemo);

  return ret_val;
}

/**
 * Encrypts a data buffer, usually the omemo symmetric key, using axolotl.
 * Assumes a valid session already exists.
 *
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 * @param recipient_addr_p Pointer to the lurch_addr of the recipient.
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 * @param key_p Pointer to the key data.
 * @param key_len Length of the key data.
 * @param axc_ctx_p Pointer to the axc_context to use.
 * @param key_ct_pp Will point to a pointer to an axc_buf containing the key ciphertext on success.
 * @return 0 on success, negative on error
 */
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static int lurch_key_encrypt(const lurch_addr * recipient_addr_p,
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                             const uint8_t * key_p,
                             size_t key_len,
                             axc_context * axc_ctx_p,
                             axc_buf ** key_ct_buf_pp) {
  int ret_val = 0;
  char * err_msg_dbg = (void *) 0;

  axc_buf * key_buf_p = (void *) 0;
  axc_buf * key_ct_buf_p = (void *) 0;
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  axc_address axc_addr = {0};
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  purple_debug_info("lurch", "%s: encrypting key for %s:%i\n", __func__, recipient_addr_p->jid, recipient_addr_p->device_id);
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  key_buf_p = axc_buf_create(key_p, key_len);
  if (!key_buf_p) {
    err_msg_dbg = g_strdup_printf("failed to create buffer for the key");
    goto cleanup;
  }

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  axc_addr.name = recipient_addr_p->jid;
  axc_addr.name_len = strnlen(axc_addr.name, JABBER_MAX_LEN_BARE);
  axc_addr.device_id = recipient_addr_p->device_id;

  ret_val = axc_message_encrypt_and_serialize(key_buf_p, &axc_addr, axc_ctx_p, &key_ct_buf_p);
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  if (ret_val) {
    err_msg_dbg = g_strdup_printf("failed to encrypt the key");
    goto cleanup;
  }

  *key_ct_buf_pp = key_ct_buf_p;

cleanup:
  if (ret_val) {
    axc_buf_free(key_ct_buf_p);
  }
  if (err_msg_dbg) {
    purple_debug_error("lurch", "%s: %s (%i)\n", __func__, err_msg_dbg, ret_val);
    free(err_msg_dbg);
  }
  axc_buf_free(key_buf_p);

  return ret_val;
}

/**
 * For each of the recipients, encrypts the symmetric key using the existing axc session,
 * then adds it to the omemo message.
 * If the session does not exist, the recipient is skipped.
 *
 * @param om_msg_p Pointer to the omemo message.
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 * @param addr_l_p Pointer to the head of a list of the intended recipients' lurch_addrs.
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 * @param axc_ctx_p Pointer to the axc_context to use.
 * @return 0 on success, negative on error.
 */
static int lurch_msg_encrypt_for_addrs(omemo_message * om_msg_p, GList * addr_l_p, axc_context * axc_ctx_p) {
  int ret_val = 0;
  char * err_msg_dbg = (void *) 0;

  GList * curr_l_p = (void *) 0;
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  lurch_addr * curr_addr_p = (void *) 0;
  axc_address addr = {0};
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  axc_buf * curr_key_ct_buf_p = (void *) 0;

  purple_debug_info("lurch", "%s: trying to encrypt key for %i devices\n", __func__, g_list_length(addr_l_p));

  for (curr_l_p = addr_l_p; curr_l_p; curr_l_p = curr_l_p->next) {
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    curr_addr_p = (lurch_addr *) curr_l_p->data;
    addr.name = curr_addr_p->jid;
    addr.name_len = strnlen(addr.name, JABBER_MAX_LEN_BARE);
    addr.device_id = curr_addr_p->device_id;
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    ret_val = axc_session_exists_initiated(&addr, axc_ctx_p);
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    if (ret_val < 0) {
      err_msg_dbg = g_strdup_printf("failed to check if session exists, aborting");
      goto cleanup;
    } else if (!ret_val) {
      continue;
    } else {
      ret_val = lurch_key_encrypt(curr_addr_p,
                                  omemo_message_get_key(om_msg_p),
                                  omemo_message_get_key_len(om_msg_p),
                                  axc_ctx_p,
                                  &curr_key_ct_buf_p);
      if (ret_val) {
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        err_msg_dbg = g_strdup_printf("failed to encrypt key for %s:%i", curr_addr_p->jid, curr_addr_p->device_id);
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        goto cleanup;
      }

      ret_val = omemo_message_add_recipient(om_msg_p,
                                            curr_addr_p->device_id,
                                            axc_buf_get_data(curr_key_ct_buf_p),
                                            axc_buf_get_len(curr_key_ct_buf_p));
      if (ret_val) {
        err_msg_dbg = g_strdup_printf("failed to add recipient to omemo msg");
        goto cleanup;
      }

      axc_buf_free(curr_key_ct_buf_p);
      curr_key_ct_buf_p = (void *) 0;
    }
  }

cleanup:
  if (err_msg_dbg) {
    purple_debug_error("lurch", "%s: %s (%i)\n", __func__, err_msg_dbg, ret_val);
    free(err_msg_dbg);
  }
  axc_buf_free(curr_key_ct_buf_p);

  return ret_val;
}

/**
 * Collects the information needed for a bundle and publishes it.
 *
 * @param uname The username.
 * @param js_p Pointer to the connection to use for publishing.
 */
static int lurch_bundle_publish_own(JabberStream * js_p) {
  int ret_val = 0;
  char * err_msg_dbg = (void *) 0;

  char * uname = (void *) 0;
  axc_context * axc_ctx_p = (void *) 0;
  axc_bundle * axcbundle_p = (void *) 0;
  omemo_bundle * omemobundle_p = (void *) 0;
  axc_buf * curr_buf_p = (void *) 0;
  axc_buf_list_item * next_p = (void *) 0;
  char * bundle_xml = (void *) 0;
  xmlnode * publish_node_bundle_p = (void *) 0;

  uname = lurch_uname_strip(purple_account_get_username(purple_connection_get_account(js_p->gc)));

  ret_val = lurch_axc_get_init_ctx(uname, &axc_ctx_p);
  if (ret_val) {
    err_msg_dbg = g_strdup_printf("failed to init axc ctx");
    goto cleanup;
  }

  ret_val = axc_bundle_collect(AXC_PRE_KEYS_AMOUNT, axc_ctx_p, &axcbundle_p);
  if (ret_val) {
    err_msg_dbg = g_strdup_printf("failed to collect axc bundle");
    goto cleanup;
  }

  ret_val = omemo_bundle_create(&omemobundle_p);
  if (ret_val) {
    err_msg_dbg = g_strdup_printf("failed to create omemo_bundle");
    goto cleanup;
  }

  ret_val = omemo_bundle_set_device_id(omemobundle_p, axc_bundle_get_reg_id(axcbundle_p));
  if (ret_val) {
    err_msg_dbg = g_strdup_printf("failed to set device id in omemo bundle");
    goto cleanup;
  }

  curr_buf_p = axc_bundle_get_signed_pre_key(axcbundle_p);
  ret_val = omemo_bundle_set_signed_pre_key(omemobundle_p,
                                            axc_bundle_get_signed_pre_key_id(axcbundle_p),
                                            axc_buf_get_data(curr_buf_p),
                                            axc_buf_get_len(curr_buf_p));
  if(ret_val) {
    err_msg_dbg = g_strdup_printf("failed to set signed pre key in omemo bundle");
    goto cleanup;
  }

  curr_buf_p = axc_bundle_get_signature(axcbundle_p);
  ret_val = omemo_bundle_set_signature(omemobundle_p,
                                       axc_buf_get_data(curr_buf_p),
                                       axc_buf_get_len(curr_buf_p));
  if (ret_val) {
    err_msg_dbg = g_strdup_printf("failed to set signature in omemo bundle");
    goto cleanup;
  }

  curr_buf_p = axc_bundle_get_identity_key(axcbundle_p);
  ret_val = omemo_bundle_set_identity_key(omemobundle_p,
                                          axc_buf_get_data(curr_buf_p),
                                          axc_buf_get_len(curr_buf_p));
  if (ret_val) {
    err_msg_dbg = g_strdup_printf("failed to set public identity key in omemo bundle");
    goto cleanup;
  }

  next_p = axc_bundle_get_pre_key_list(axcbundle_p);
  while (next_p) {
    curr_buf_p = axc_buf_list_item_get_buf(next_p);
    ret_val = omemo_bundle_add_pre_key(omemobundle_p,
                                       axc_buf_list_item_get_id(next_p),
                                       axc_buf_get_data(curr_buf_p),
                                       axc_buf_get_len(curr_buf_p));
    if (ret_val) {
      err_msg_dbg = g_strdup_printf("failed to add public pre key to omemo bundle");
      goto cleanup;
    }
    next_p = axc_buf_list_item_get_next(next_p);
  }

  ret_val = omemo_bundle_export(omemobundle_p, &bundle_xml);
  if (ret_val) {
    err_msg_dbg = g_strdup_printf("failed to export omemo bundle to xml");
    goto cleanup;
  }

  publish_node_bundle_p = xmlnode_from_str(bundle_xml, -1);
  jabber_pep_publish(js_p, publish_node_bundle_p);

  purple_debug_info("lurch", "%s: published own bundle for %s\n", __func__, uname);

cleanup:
  if (err_msg_dbg) {
    purple_debug_error("lurch", "%s: %s (%i)\n", __func__, err_msg_dbg, ret_val);
    free(err_msg_dbg);
  }
  free(uname);
  axc_context_destroy_all(axc_ctx_p);
  axc_bundle_destroy(axcbundle_p);
  omemo_bundle_destroy(omemobundle_p);
  free(bundle_xml);

  return ret_val;
}

/**
 * Parses the device ID from a received bundle update.
 *
 * @param bundle_node_ns The node name.
 * @return The ID.
 */
static uint32_t lurch_bundle_name_get_device_id(const char * bundle_node_name) {
  char ** split = (void *) 0;
  uint32_t id = 0;

  split = g_strsplit(bundle_node_name, ":", -1);
  id = strtol(split[5], (void *) 0, 0);

  g_strfreev(split);

  return id;
}

/**
 * Creates an axc session from a received bundle.
 *
 * @param uname The own username.
 * @param from The sender of the bundle.
 * @param items_p The bundle update as received in the PEP request handler.
 */
static int lurch_bundle_create_session(const char * uname,
                                       const char * from,
                                       const xmlnode * items_p,
                                       axc_context * axc_ctx_p) {
  int ret_val = 0;
  char * err_msg_dbg = (void *) 0;

  int len;
  omemo_bundle * om_bundle_p = (void *) 0;
  axc_address remote_addr = {0};
  uint32_t pre_key_id = 0;
  uint8_t * pre_key_p = (void *) 0;
  size_t pre_key_len = 0;
  uint32_t signed_pre_key_id = 0;
  uint8_t * signed_pre_key_p = (void *) 0;
  size_t signed_pre_key_len = 0;
  uint8_t * signature_p = (void *) 0;
  size_t signature_len = 0;
  uint8_t * identity_key_p = (void *) 0;
  size_t identity_key_len = 0;
  axc_buf * pre_key_buf_p = (void *) 0;
  axc_buf * signed_pre_key_buf_p = (void *) 0;
  axc_buf * signature_buf_p = (void *) 0;
  axc_buf * identity_key_buf_p = (void *) 0;

  purple_debug_info("lurch", "%s: creating a session between %s and %s from a received bundle\n", __func__, uname, from);

  ret_val = omemo_bundle_import(xmlnode_to_str(items_p, &len), &om_bundle_p);
  if (ret_val) {
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    err_msg_dbg = g_strdup_printf("failed to import xml into bundle");
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    goto cleanup;
  }

  remote_addr.name = from;
  remote_addr.name_len = strnlen(from, JABBER_MAX_LEN_BARE);
  remote_addr.device_id = omemo_bundle_get_device_id(om_bundle_p);

  purple_debug_info("lurch", "%s: bundle's device id is %i\n", __func__, remote_addr.device_id);

  ret_val = omemo_bundle_get_random_pre_key(om_bundle_p, &pre_key_id, &pre_key_p, &pre_key_len);
  if (ret_val) {
    err_msg_dbg = g_strdup_printf("failed get a random pre key from the bundle");
    goto cleanup;
  }
  ret_val = omemo_bundle_get_signed_pre_key(om_bundle_p, &signed_pre_key_id, &signed_pre_key_p, &signed_pre_key_len);
  if (ret_val) {
    err_msg_dbg = g_strdup_printf("failed to get the signed pre key from the bundle");
    goto cleanup;
  }
  ret_val = omemo_bundle_get_signature(om_bundle_p, &signature_p, &signature_len);
  if (ret_val) {
    err_msg_dbg = g_strdup_printf("failed to get the signature from the bundle");
    goto cleanup;
  }
  ret_val = omemo_bundle_get_identity_key(om_bundle_p, &identity_key_p, &identity_key_len);
  if (ret_val) {
    err_msg_dbg = g_strdup_printf("failed to get the public identity key from the bundle");
    goto cleanup;
  }

  pre_key_buf_p = axc_buf_create(pre_key_p, pre_key_len);
  signed_pre_key_buf_p = axc_buf_create(signed_pre_key_p, signed_pre_key_len);
  signature_buf_p = axc_buf_create(signature_p, signature_len);
  identity_key_buf_p = axc_buf_create(identity_key_p, identity_key_len);

  if (!pre_key_buf_p || !signed_pre_key_buf_p || !signature_buf_p || !identity_key_buf_p) {
    ret_val = LURCH_ERR;
    err_msg_dbg = g_strdup_printf("failed to create one of the buffers");
    goto cleanup;
  }

  ret_val = axc_session_from_bundle(pre_key_id, pre_key_buf_p,
                                    signed_pre_key_id, signed_pre_key_buf_p,
                                    signature_buf_p,
                                    identity_key_buf_p,
                                    &remote_addr,
                                    axc_ctx_p);
  if (ret_val) {
    err_msg_dbg = g_strdup_printf("failed to create a session from a bundle");
    goto cleanup;
  }

cleanup:
  if (err_msg_dbg) {
    purple_debug_error("lurch", "%s: %s (%i)\n", __func__, err_msg_dbg, ret_val);
    free(err_msg_dbg);
  }
  omemo_bundle_destroy(om_bundle_p);
  free(pre_key_p);
  free(signed_pre_key_p);
  free(signature_p);
  free(identity_key_p);
  axc_buf_free(pre_key_buf_p);
  axc_buf_free(signed_pre_key_buf_p);
  axc_buf_free(signature_buf_p);
  axc_buf_free(identity_key_buf_p);

  return ret_val;
}

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/**
 * Wraps the omemo_message_export_encrypted message, so that it is called with the same options throughout.
 */
static int lurch_export_encrypted(omemo_message * om_msg_p, char ** xml_pp) {
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  return omemo_message_export_encrypted(om_msg_p, OMEMO_ADD_MSG_EME, xml_pp);
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}

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/**
 * Implements JabberIqCallback.
 * Callback for a bundle request.
 */
static void lurch_bundle_request_cb(JabberStream * js_p, const char * from,
                                    JabberIqType type, const char * id,
                                    xmlnode * packet_p, gpointer data_p) {
  int ret_val = 0;
  char * err_msg_conv = (void *) 0;
  char * err_msg_dbg = (void *) 0;

  char * uname = (void *) 0;
  char ** split = (void *) 0;
  char * device_id_str = (void *) 0;
  axc_address addr = {0};
  axc_context * axc_ctx_p = (void *) 0;
  char * recipient = (void *) 0;
  xmlnode * pubsub_node_p = (void *) 0;
  xmlnode * items_node_p = (void *) 0;
  int msg_handled = 0;
  char * addr_key = (void *) 0;
  char * msg_xml = (void *) 0;
  xmlnode * msg_node_p = (void *) 0;
  lurch_queued_msg * qmsg_p = (lurch_queued_msg *) data_p;

  uname = lurch_uname_strip(purple_account_get_username(purple_connection_get_account(js_p->gc)));
  recipient = omemo_message_get_recipient_name_bare(qmsg_p->om_msg_p);

  if (!from) {
    // own user
    from = uname;
  }

  split = g_strsplit(id, "#", 3);
  device_id_str = split[1];

  purple_debug_info("lurch", "%s: %s received bundle update from %s:%s\n", __func__, uname, from, device_id_str);

  addr.name = from;
  addr.name_len = strnlen(from, JABBER_MAX_LEN_BARE);
  addr.device_id = strtol(device_id_str, (void *) 0, 10);

  ret_val = lurch_axc_get_init_ctx(uname, &axc_ctx_p);
  if (ret_val) {
    err_msg_dbg = "failed to get axc ctx";
    goto cleanup;
  }

  if (type == JABBER_IQ_ERROR) {
    err_msg_conv = g_strdup_printf("The device %s owned by %s does not have a bundle and will be skipped. "
                                   "The owner should fix this, or remove the device from the list.", device_id_str, from);

  } else {
    pubsub_node_p = xmlnode_get_child(packet_p, "pubsub");
    if (!pubsub_node_p) {
      ret_val = LURCH_ERR;
      err_msg_dbg = "no <pubsub> node in response";
      goto cleanup;
    }

    items_node_p = xmlnode_get_child(pubsub_node_p, "items");
    if (!items_node_p) {
      ret_val = LURCH_ERR;
      err_msg_dbg = "no <items> node in response";
      goto cleanup;
    }

    ret_val = axc_session_exists_initiated(&addr, axc_ctx_p);
    if (!ret_val) {
      ret_val = lurch_bundle_create_session(uname, from, items_node_p, axc_ctx_p);
      if (ret_val) {
        err_msg_dbg = "failed to create a session";
        goto cleanup;
      }
    } else if (ret_val < 0) {
      err_msg_dbg = "failed to check if session exists";
      goto cleanup;
    }
  }

  addr_key = lurch_queue_make_key_string_s(from, device_id_str);
  if (!addr_key) {
    err_msg_dbg = "failed to make a key string";
    ret_val = LURCH_ERR;
    goto cleanup;
  }

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  (void) g_hash_table_replace(qmsg_p->sess_handled_p, addr_key, addr_key);
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  if (lurch_queued_msg_is_handled(qmsg_p)) {
    msg_handled = 1;
  }

  if (msg_handled) {
    ret_val = lurch_msg_encrypt_for_addrs(qmsg_p->om_msg_p, qmsg_p->recipient_addr_l_p, axc_ctx_p);
    if (ret_val) {
      err_msg_dbg = "failed to encrypt the symmetric key";
      goto cleanup;
    }

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    ret_val = lurch_export_encrypted(qmsg_p->om_msg_p, &msg_xml);
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    if (ret_val) {
      err_msg_dbg = "failed to export the message to xml";
      goto cleanup;
    }

    msg_node_p = xmlnode_from_str(msg_xml, -1);
    if (!msg_node_p) {
      err_msg_dbg = "failed to parse xml from string";
      ret_val = LURCH_ERR;
      goto cleanup;
    }

    purple_debug_info("lurch", "sending encrypted msg\n");
    purple_signal_emit(purple_plugins_find_with_id("prpl-jabber"), "jabber-sending-xmlnode", js_p->gc, &msg_node_p);

    lurch_queued_msg_destroy(qmsg_p);
  }

cleanup:
  if (err_msg_conv) {
    purple_conv_present_error(recipient, purple_connection_get_account(js_p->gc), err_msg_conv);
    g_free(err_msg_conv);
  }
  if (err_msg_dbg) {
    purple_conv_present_error(recipient, purple_connection_get_account(js_p->gc), LURCH_ERR_STRING_ENCRYPT);
    purple_debug_error("lurch", "%s: %s (%i)\n", __func__, err_msg_dbg, ret_val);
  }

  free(uname);
  g_strfreev(split);
  axc_context_destroy_all(axc_ctx_p);
  free(addr_key);
  free(recipient);
  free(msg_xml);
  if (msg_node_p) {
    xmlnode_free(msg_node_p);
  }
}

/**
 * Requests a bundle.
 *
 * @param js_p Pointer to the JabberStream to use.
 * @param to The recipient of this request.
 * @param device_id The ID of the device whose bundle is needed.
 * @param qmsg_p Pointer to the queued message waiting on (at least) this bundle.
 * @return 0 on success, negative on error.
 */
static int lurch_bundle_request_do(JabberStream * js_p,
                                   const char * to,
                                   uint32_t device_id,
                                   lurch_queued_msg * qmsg_p) {
  int ret_val = 0;

  JabberIq * jiq_p = (void *) 0;
  xmlnode * pubsub_node_p = (void *) 0;
  char * device_id_str = (void *) 0;
  char * rand_str = (void *) 0;
  char * req_id = (void *) 0;
  char * bundle_node_name = (void *) 0;
  xmlnode * items_node_p = (void *) 0;

  purple_debug_info("lurch", "%s: %s is requesting bundle from %s:%i\n", __func__,
                    purple_account_get_username(purple_connection_get_account(js_p->gc)), to, device_id);

  jiq_p = jabber_iq_new(js_p, JABBER_IQ_GET);
  xmlnode_set_attrib(jiq_p->node, "to", to);

  pubsub_node_p = xmlnode_new_child(jiq_p->node, "pubsub");
  xmlnode_set_namespace(pubsub_node_p, "http://jabber.org/protocol/pubsub");

  device_id_str = g_strdup_printf("%i", device_id);
  rand_str = g_strdup_printf("%i", g_random_int());
  req_id = g_strconcat(to, "#", device_id_str, "#", rand_str, NULL);

  ret_val = omemo_bundle_get_pep_node_name(device_id, &bundle_node_name);
  if (ret_val) {
    purple_debug_error("lurch", "%s: failed to get bundle pep node name for %s:%i\n", __func__, to, device_id);
    goto cleanup;
  }

  items_node_p = xmlnode_new_child(pubsub_node_p, "items");
  xmlnode_set_attrib(items_node_p, "node", bundle_node_name);
  xmlnode_set_attrib(items_node_p, "max_items", "1");

  jabber_iq_set_id(jiq_p, req_id);
  jabber_iq_set_callback(jiq_p, lurch_bundle_request_cb, qmsg_p);

  jabber_iq_send(jiq_p);

  purple_debug_info("lurch", "%s: ...request sent\n", __func__);

cleanup:
  g_free(device_id_str);
  g_free(rand_str);
  g_free(req_id);
  g_free(bundle_node_name);

  return ret_val;
}

/**
 * A JabberPEPHandler function.
 * When a prekey message containing an invalid key ID is received,
 * the bundle of the sender is requested and a KeyTransport message is sent
 * in response so that a session can still be established.
 */
static void lurch_pep_bundle_for_keytransport(JabberStream * js_p, const char * from, xmlnode * items_p) {
  int ret_val = 0;
  char * err_msg_dbg = (void *) 0;

  char * uname = (void *) 0;
  axc_context * axc_ctx_p = (void *) 0;
  uint32_t own_id = 0;
  omemo_message * msg_p = (void *) 0;
  axc_address addr = {0};
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  lurch_addr laddr = {0};
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  axc_buf * key_ct_buf_p = (void *) 0;
  char * msg_xml = (void *) 0;
  xmlnode * msg_node_p = (void *) 0;
  void * jabber_handle_p = purple_plugins_find_with_id("prpl-jabber");

  uname = lurch_uname_strip(purple_account_get_username(purple_connection_get_account(js_p->gc)));

  addr.name = from;
  addr.name_len = strnlen(from, JABBER_MAX_LEN_BARE);
  addr.device_id = lurch_bundle_name_get_device_id(xmlnode_get_attrib(items_p, "node"));

  purple_debug_info("lurch", "%s: %s received bundle from %s:%i\n", __func__, uname, from, addr.device_id);

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  laddr.jid = g_strndup(addr.name, addr.name_len);
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  laddr.device_id = addr.device_id;

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  ret_val = lurch_axc_get_init_ctx(uname, &axc_ctx_p);
  if (ret_val) {
    err_msg_dbg = g_strdup_printf("failed to init axc ctx");
    goto cleanup;
  }

  // make sure it's gonna be a pre_key_message
  ret_val = axc_session_delete(addr.name, addr.device_id, axc_ctx_p);
  if (ret_val) {
    err_msg_dbg = g_strdup_printf("failed to delete possibly existing session");
    goto cleanup;
  }

  ret_val = lurch_bundle_create_session(uname, from, items_p, axc_ctx_p);
  if (ret_val) {
    err_msg_dbg = g_strdup_printf("failed to create session");
    goto cleanup;
  }

  purple_debug_info("lurch", "%s: %s created session with %s:%i\n", __func__, uname, from, addr.device_id);

  ret_val = axc_get_device_id(axc_ctx_p, &own_id);
  if (ret_val) {
    err_msg_dbg = g_strdup_printf("failed to get own device id");
    goto cleanup;
  }

  ret_val = omemo_message_create(own_id, &crypto, &msg_p);
  if (ret_val) {
    err_msg_dbg = g_strdup_printf("failed to create omemo msg");
    goto cleanup;
  }

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  ret_val = lurch_key_encrypt(&laddr,
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                              omemo_message_get_key(msg_p),
                              omemo_message_get_key_len(msg_p),
                              axc_ctx_p,
                              &key_ct_buf_p);
  if (ret_val) {
    err_msg_dbg = g_strdup_printf("failed to encrypt key for %s:%i", addr.name, addr.device_id);
    goto cleanup;
  }

  ret_val = omemo_message_add_recipient(msg_p,
                                        addr.device_id,
                                        axc_buf_get_data(key_ct_buf_p),
                                        axc_buf_get_len(key_ct_buf_p));
  if (ret_val) {
    err_msg_dbg = g_strdup_printf("failed to add %s:%i as recipient to message", addr.name, addr.device_id);
    goto cleanup;
  }

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  // don't call wrapper function here as EME is not necessary
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  ret_val = omemo_message_export_encrypted(msg_p, OMEMO_ADD_MSG_NONE, &msg_xml);
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  if (ret_val) {
    err_msg_dbg = g_strdup_printf("failed to export encrypted msg");
    goto cleanup;
  }

  msg_node_p = xmlnode_from_str(msg_xml, -1);
  if (!msg_node_p) {