Add initial JID parsing

8 files changed, 150 insertions, 109 deletions

diff --git a/README b/README
index 16644cc..f8c38de 100644
--- a/README
+++ b/README
@@ -46,7 +46,7 @@ A rough roadmap:
 
 [.] Doxygen documentation.
 [.] Texinfo manual.
-[ ] Proper JID handling (RFC 7622).
+[.] Proper JID handling (RFC 7622).
 [ ] Abstraction of the used XML, SASL, TLS, and DNS libraries, and
     optional usage of alternative ones. Though maybe shouldn't
     abstract out XML functions and structures: could reuse existing
diff --git a/examples/basic.c b/examples/basic.c
index 88a1ca4..09a98c4 100644
--- a/examples/basic.c
+++ b/examples/basic.c
@@ -37,16 +37,8 @@ int my_sasl_property_cb (rexmpp_t *s, Gsasl_property prop) {
     return GSASL_OK;
   }
   if (prop == GSASL_AUTHID) {
-    char *domainpart = strchr(s->initial_jid, '@');
-    if (domainpart != NULL) {
-      int localpart_len = domainpart - s->initial_jid;
-      char *localpart = malloc(localpart_len + 1);
-      localpart[localpart_len] = 0;
-      strncpy(localpart, s->initial_jid, localpart_len);
-      gsasl_property_set (s->sasl_session, GSASL_AUTHID, localpart);
-      free(localpart);
-      return GSASL_OK;
-    }
+    gsasl_property_set (s->sasl_session, GSASL_AUTHID, s->initial_jid.local);
+    return GSASL_OK;
   }
   printf("unhandled gsasl property: %d\n", prop);
   return GSASL_NO_CALLBACK;
diff --git a/examples/weechat.c b/examples/weechat.c
index dc6c957..46b9093 100644
--- a/examples/weechat.c
+++ b/examples/weechat.c
@@ -28,6 +28,7 @@
 #include "weechat-plugin.h"
 #include "rexmpp.h"
 #include "rexmpp_roster.h"
+#include "rexmpp_jid.h"
 
 WEECHAT_PLUGIN_NAME("rexmpp");
 WEECHAT_PLUGIN_DESCRIPTION("XMPP plugin using librexmpp");
@@ -80,16 +81,8 @@ int my_sasl_property_cb (rexmpp_t *s, Gsasl_property prop) {
     return GSASL_OK;
   }
   if (prop == GSASL_AUTHID) {
-    char *domainpart = strchr(s->initial_jid, '@');
-    if (domainpart != NULL) {
-      int localpart_len = domainpart - s->initial_jid;
-      char *localpart = malloc(localpart_len + 1);
-      localpart[localpart_len] = 0;
-      strncpy(localpart, s->initial_jid, localpart_len);
-      gsasl_property_set (s->sasl_session, GSASL_AUTHID, localpart);
-      free(localpart);
-      return GSASL_OK;
-    }
+    gsasl_property_set (s->sasl_session, GSASL_AUTHID, s->initial_jid.local);
+    return GSASL_OK;
   }
   weechat_printf(wr->server_buffer, "unhandled gsasl property: %d\n", prop);
   return GSASL_NO_CALLBACK;
@@ -137,7 +130,7 @@ int muc_close_cb (const void *ptr, void *data,
   struct weechat_rexmpp_muc *wrm = (void*)ptr;
   rexmpp_t *s = &wrm->wr->rexmpp_state;
   xmlNodePtr presence = rexmpp_xml_add_id(s, xmlNewNode(NULL, "presence"));
-  xmlNewProp(presence, "from", s->assigned_jid);
+  xmlNewProp(presence, "from", s->assigned_jid.full);
   xmlNewProp(presence, "to", wrm->jid);
   xmlNewProp(presence, "type", "unavailable");
   rexmpp_send(s, presence);
@@ -152,27 +145,21 @@ int my_xml_in_cb (rexmpp_t *s, xmlNodePtr node) {
   /* free(xml_buf); */
   if (rexmpp_xml_match(node, "jabber:client", "message")) {
     char *from = xmlGetProp(node, "from");
-    char *display_name = from;
-    int i, resource_removed = 0;
-    for (i = 0; i < strlen(from); i++) {
-      if (from[i] == '/') {
-        from[i] = 0;
-        display_name = from + i + 1;
-        resource_removed = 1;
-        break;
-      }
-    }
     if (from != NULL) {
-      struct t_gui_buffer *buf = weechat_buffer_search("rexmpp", from);
+      struct rexmpp_jid from_jid;
+      rexmpp_jid_parse(from, &from_jid);
+      xmlFree(from);
+      char *display_name = from_jid.full;
+      if (from_jid.resource[0]) {
+        display_name = from_jid.resource;
+      }
+      struct t_gui_buffer *buf = weechat_buffer_search("rexmpp", from_jid.bare);
       if (buf == NULL) {
-        buf = weechat_buffer_new (from,
+        buf = weechat_buffer_new (from_jid.bare,
                                   &query_input_cb, wr, NULL,
                                   &query_close_cb, wr, NULL);
         weechat_buffer_set(buf, "nicklist", "1");
       }
-      if (resource_removed) {
-        from[i] = '/';            /* restore */
-      }
       xmlNodePtr body = rexmpp_xml_find_child(node, "jabber:client", "body");
       if (body != NULL) {
         xmlChar *str = xmlNodeGetContent(body);
@@ -183,40 +170,33 @@ int my_xml_in_cb (rexmpp_t *s, xmlNodePtr node) {
           xmlFree(str);
         }
       }
-      xmlFree(from);
     }
   }
   if (rexmpp_xml_match(node, "jabber:client", "presence")) {
     char *presence_type = xmlGetProp(node, "type");
-    char *jid = xmlGetProp(node, "from");
-    char *full_jid = strdup(jid);
-    int i;
-    char *resource = "";
-    for (i = 0; i < strlen(jid); i++) {
-      if (jid[i] == '/') {
-        jid[i] = 0;
-        resource = jid + i + 1;
-        break;
-      }
-    }
+    char *from = xmlGetProp(node, "from");
+    struct rexmpp_jid from_jid;
+    rexmpp_jid_parse(from, &from_jid);
+    xmlFree(from);
+
     if (rexmpp_xml_find_child(node, "http://jabber.org/protocol/muc#user", "x")) {
       /* Update MUC nicklist */
-      struct t_gui_buffer *buf = weechat_buffer_search("rexmpp", jid);
+      struct t_gui_buffer *buf = weechat_buffer_search("rexmpp", from_jid.bare);
       if (buf != NULL) {
         if (presence_type != NULL && strcmp(presence_type, "unavailable") == 0) {
           struct t_gui_nick *nick =
-            weechat_nicklist_search_nick(buf, NULL, resource);
+            weechat_nicklist_search_nick(buf, NULL, from_jid.resource);
           if (nick != NULL) {
             weechat_nicklist_remove_nick(buf, nick);
           }
         } else {
-          weechat_nicklist_add_nick(buf, NULL, resource,
+          weechat_nicklist_add_nick(buf, NULL, from_jid.resource,
                                     "bar_fg", "", "lightgreen", 1);
         }
       }
-    } else if (rexmpp_roster_find_item(s, jid, NULL) != NULL) {
+    } else if (rexmpp_roster_find_item(s, from_jid.bare, NULL) != NULL) {
       /* A roster item. */
-      struct t_gui_nick *nick = weechat_nicklist_search_nick(wr->server_buffer, NULL, jid);
+      struct t_gui_nick *nick = weechat_nicklist_search_nick(wr->server_buffer, NULL, from_jid.bare);
       if (presence_type == NULL) {
         /* An "available" presence: just ensure that it's shown as
            online. */
@@ -228,25 +208,23 @@ int my_xml_in_cb (rexmpp_t *s, xmlNodePtr node) {
            just went offline). */
         xmlNodePtr cur;
         int found = 0;
+        struct rexmpp_jid cur_from_jid;
         for (cur = s->roster_presence;
              cur != NULL;
              cur = xmlNextElementSibling(cur)) {
           char *cur_from = xmlGetProp(cur, "from");
-          if (strcmp(cur_from, full_jid) != 0 &&
-              strncmp(cur_from, jid, strlen(jid)) == 0 &&
-              strlen(cur_from) > strlen(jid) &&
-              cur_from[strlen(jid)] == '/') {
+          rexmpp_jid_parse(cur_from, &cur_from_jid);
+          xmlFree(cur_from);
+          if (strcmp(cur_from_jid.bare, from_jid.bare) == 0 &&
+              strcmp(cur_from_jid.resource, from_jid.resource) != 0) {
             found = 1;
           }
-          free(cur_from);
         }
         if (! found) {
           weechat_nicklist_nick_set(wr->server_buffer, nick, "prefix", "");
         }
       }
     }
-    free(jid);
-    free(full_jid);
     if (presence_type != NULL) {
       free(presence_type);
     }
@@ -295,7 +273,7 @@ my_input_cb (const void *ptr, void *data,
   } else if (input_data[0] == 'j' && input_data[1] == ' ') {
     char *jid = strdup(input_data + 2);
     xmlNodePtr presence = rexmpp_xml_add_id(s, xmlNewNode(NULL, "presence"));
-    xmlNewProp(presence, "from", s->assigned_jid);
+    xmlNewProp(presence, "from", s->assigned_jid.full);
     xmlNewProp(presence, "to", jid);
     xmlNodePtr x = xmlNewNode(NULL, "x");
     xmlNewNs(x, "http://jabber.org/protocol/muc", NULL);
diff --git a/src/Makefile.am b/src/Makefile.am
index 3a977cd..e66a276 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -12,8 +12,10 @@ librexmpp_la_SOURCES = rexmpp_roster.h rexmpp_roster.c \
 	rexmpp_tcp.h rexmpp_tcp.c \
 	rexmpp_socks.h rexmpp_socks.c \
 	rexmpp.h rexmpp.c \
-	rexmpp_dns.h rexmpp_dns.c
-include_HEADERS = rexmpp_roster.h rexmpp_tcp.h rexmpp_socks.h rexmpp.h rexmpp_dns.h
+	rexmpp_dns.h rexmpp_dns.c \
+	rexmpp_jid.h rexmpp_jid.c
+include_HEADERS = rexmpp_roster.h rexmpp_tcp.h rexmpp_socks.h rexmpp.h \
+	rexmpp_dns.h rexmpp_jid.h
 librexmpp_la_CFLAGS = $(AM_CFLAGS) $(LIBXML_CFLAGS) $(GNUTLS_CFLAGS) \
 	$(LIBDANE_CFLAGS) $(GSASL_CFLAGS) $(UNBOUND_CFLAGS)
 librexmpp_la_LIBADD = $(LIBXML_LIBS) $(GNUTLS_LIBS) $(LIBDANE_LIBS) \
diff --git a/src/rexmpp.c b/src/rexmpp.c
index f6bf7c3..b0d8d94 100644
--- a/src/rexmpp.c
+++ b/src/rexmpp.c
@@ -28,6 +28,7 @@
 #include "rexmpp_socks.h"
 #include "rexmpp_roster.h"
 #include "rexmpp_dns.h"
+#include "rexmpp_jid.h"
 
 void rexmpp_sax_start_elem_ns (rexmpp_t *s,
                                const char *localname,
@@ -268,8 +269,8 @@ rexmpp_err_t rexmpp_init (rexmpp_t *s, const char *jid)
   s->reconnect_number = 0;
   s->next_reconnect_time.tv_sec = 0;
   s->next_reconnect_time.tv_usec = 0;
-  s->initial_jid = NULL;
-  s->assigned_jid = NULL;
+  s->initial_jid.full[0] = '\0';
+  s->assigned_jid.full[0] = '\0';
   s->stanza_queue_size = 1024;
   s->send_queue_size = 1024;
   s->iq_queue_size = 1024;
@@ -287,7 +288,10 @@ rexmpp_err_t rexmpp_init (rexmpp_t *s, const char *jid)
     return REXMPP_E_JID;
   }
 
-  s->initial_jid = strdup(jid);
+  if (rexmpp_jid_parse(jid, &(s->initial_jid))) {
+    rexmpp_log(s, LOG_CRIT, "Failed to parse the initial JID.");
+    return REXMPP_E_JID;
+  }
 
   s->xml_parser = xmlCreatePushParserCtxt(&sax, s, "", 0, NULL);
 
@@ -422,10 +426,6 @@ void rexmpp_done (rexmpp_t *s) {
     s->resolver_ctx = NULL;
   }
   xmlFreeParserCtxt(s->xml_parser);
-  if (s->initial_jid != NULL) {
-    free(s->initial_jid);
-    s->initial_jid = NULL;
-  }
   if (s->stream_id != NULL) {
     free(s->stream_id);
     s->stream_id = NULL;
@@ -565,8 +565,8 @@ xmlNodePtr rexmpp_xml_set_delay (rexmpp_t *s, xmlNodePtr node) {
   strftime(buf, 42, "%FT%T%z", local_time);
   xmlNodePtr delay = xmlNewChild(node, NULL, "delay", NULL);
   xmlNewProp(delay, "stamp", buf);
-  if (s != NULL && s->assigned_jid != NULL) {
-    xmlNewProp(delay, "from", s->assigned_jid);
+  if (s != NULL && s->assigned_jid.full[0]) {
+    xmlNewProp(delay, "from", s->assigned_jid.full);
   }
   return node;
 }
@@ -777,8 +777,8 @@ void rexmpp_iq_reply (rexmpp_t *s,
     xmlNewProp(iq_stanza, "to", to);
     free(to);
   }
-  if (s->assigned_jid != NULL) {
-    xmlNewProp(iq_stanza, "from", s->assigned_jid);
+  if (s->assigned_jid.full[0]) {
+    xmlNewProp(iq_stanza, "from", s->assigned_jid.full);
   }
   if (payload != NULL) {
     xmlAddChild(iq_stanza, payload);
@@ -815,8 +815,8 @@ rexmpp_err_t rexmpp_iq_new (rexmpp_t *s,
   if (to != NULL) {
     xmlNewProp(iq_stanza, "to", to);
   }
-  if (s->assigned_jid != NULL) {
-    xmlNewProp(iq_stanza, "from", s->assigned_jid);
+  if (s->assigned_jid.full[0]) {
+    xmlNewProp(iq_stanza, "from", s->assigned_jid.full);
   }
   xmlAddChild(iq_stanza, payload);
   rexmpp_iq_t *iq = malloc(sizeof(rexmpp_iq_t));
@@ -935,7 +935,7 @@ rexmpp_err_t rexmpp_stream_open (rexmpp_t *s) {
            "<stream:stream to='%s' version='1.0' "
            "xml:lang='en' xmlns='jabber:client' "
            "xmlns:stream='http://etherx.jabber.org/streams'>",
-           jid_bare_to_host(s->initial_jid));
+           s->initial_jid.domain);
   s->stream_state = REXMPP_STREAM_OPENING;
   return rexmpp_send_raw(s, buf, strlen(buf));
 }
@@ -1066,7 +1066,7 @@ rexmpp_err_t rexmpp_tls_handshake (rexmpp_t *s) {
     }
 
     ret = gnutls_certificate_verify_peers3(s->gnutls_session,
-                                           jid_bare_to_host(s->initial_jid),
+                                           s->initial_jid.domain,
                                            &status);
     if (ret || status) {
       s->tls_state = REXMPP_TLS_ERROR;
@@ -1131,8 +1131,8 @@ rexmpp_err_t rexmpp_tls_start (rexmpp_t *s) {
   gnutls_session_set_ptr(s->gnutls_session, s);
   gnutls_alpn_set_protocols(s->gnutls_session, &xmpp_client_protocol, 1, 0);
   gnutls_server_name_set(s->gnutls_session, GNUTLS_NAME_DNS,
-                         jid_bare_to_host(s->initial_jid),
-                         strlen(jid_bare_to_host(s->initial_jid)));
+                         s->initial_jid.domain,
+                         strlen(s->initial_jid.domain));
   gnutls_set_default_priority(s->gnutls_session);
   gnutls_credentials_set(s->gnutls_session, GNUTLS_CRD_CERTIFICATE,
                          s->gnutls_cred);
@@ -1247,7 +1247,7 @@ void rexmpp_srv_cb (void *s_ptr,
 
   if (s->server_srv == NULL && s->server_srv_tls == NULL) {
     /* Failed to resolve anything: a fallback. */
-    s->server_host = jid_bare_to_host(s->initial_jid);
+    s->server_host = s->initial_jid.domain;
     s->server_port = 5222;
     rexmpp_start_connecting(s);
   } else {
@@ -1375,7 +1375,7 @@ void rexmpp_stream_is_ready(rexmpp_t *s) {
   if (s->enable_service_discovery) {
     xmlNodePtr disco_query = xmlNewNode(NULL, "query");
     xmlNewNs(disco_query, "http://jabber.org/protocol/disco#info", NULL);
-    rexmpp_iq_new(s, "get", jid_bare_to_host(s->initial_jid),
+    rexmpp_iq_new(s, "get", s->initial_jid.domain,
                   disco_query, rexmpp_iq_discovery_info);
   }
   if (s->manage_roster) {
@@ -1420,8 +1420,7 @@ void rexmpp_bound (rexmpp_t *s, xmlNodePtr req, xmlNodePtr response, int success
     xmlNodePtr jid = xmlFirstElementChild(child);
     if (rexmpp_xml_match(jid, "urn:ietf:params:xml:ns:xmpp-bind", "jid")) {
       rexmpp_log(s, LOG_INFO, "jid: %s", xmlNodeGetContent(jid));
-      s->assigned_jid = malloc(strlen(xmlNodeGetContent(jid)) + 1);
-      strcpy(s->assigned_jid, xmlNodeGetContent(jid));
+      rexmpp_jid_parse(xmlNodeGetContent(jid), &(s->assigned_jid));
     }
     if (s->stream_id == NULL &&
         (child = rexmpp_xml_find_child(s->stream_features, "urn:xmpp:sm:3",
@@ -1523,7 +1522,7 @@ rexmpp_err_t rexmpp_process_element (rexmpp_t *s, xmlNodePtr elem) {
       if (from == NULL) {
         from_server = 1;
       } else {
-        if (strcmp(from, jid_bare_to_host(s->assigned_jid)) == 0) {
+        if (strcmp(from, s->initial_jid.domain) == 0) {
           from_server = 1;
         }
         free(from);
@@ -1597,21 +1596,11 @@ rexmpp_err_t rexmpp_process_element (rexmpp_t *s, xmlNodePtr elem) {
       s->track_roster_presence) {
     char *from = xmlGetProp(elem, "from");
     if (from != NULL) {
-      size_t i;
-      int resource_removed = 0;
-      for (i = 0; i < strlen(from); i++) {
-        if (from[i] == '/') {
-          from[i] = '\0';
-          resource_removed = i;
-          break;
-        }
-      }
-      if (rexmpp_roster_find_item(s, from, NULL) != NULL) {
+      struct rexmpp_jid from_jid;
+      rexmpp_jid_parse(from, &from_jid);
+      xmlFree(from);
+      if (rexmpp_roster_find_item(s, from_jid.bare, NULL) != NULL) {
         /* The bare JID is in the roster. */
-        if (resource_removed) {
-          /* Restore full JID. */
-          from[resource_removed] = '/';
-        }
         char *type = xmlGetProp(elem, "type");
         xmlNodePtr cur, prev;
         if (type == NULL || strcmp(type, "unavailable") == 0) {
@@ -1622,7 +1611,7 @@ rexmpp_err_t rexmpp_process_element (rexmpp_t *s, xmlNodePtr elem) {
                cur != NULL;
                prev = cur, cur = xmlNextElementSibling(cur)) {
             char *cur_from = xmlGetProp(cur, "from");
-            if (strcmp(cur_from, from) == 0) {
+            if (strcmp(cur_from, from_jid.full) == 0) {
               if (prev == NULL) {
                 s->roster_presence = cur->next;
               } else {
@@ -1643,7 +1632,6 @@ rexmpp_err_t rexmpp_process_element (rexmpp_t *s, xmlNodePtr elem) {
           free(type);
         }
       }
-      free(from);
     }
   }
 
@@ -2023,12 +2011,12 @@ rexmpp_err_t rexmpp_run (rexmpp_t *s, fd_set *read_fds, fd_set *write_fds) {
     if (s->manual_host == NULL) {
       /* Start by querying SRV records. */
       rexmpp_log(s, LOG_DEBUG, "start (or reconnect)");
-      size_t srv_query_buf_len = strlen(jid_bare_to_host(s->initial_jid)) +
+      size_t srv_query_buf_len = strlen(s->initial_jid.domain) +
         strlen("_xmpps-client._tcp..") +
         1;
       char *srv_query = malloc(srv_query_buf_len);
       snprintf(srv_query, srv_query_buf_len,
-               "_xmpps-client._tcp.%s.", jid_bare_to_host(s->initial_jid));
+               "_xmpps-client._tcp.%s.", s->initial_jid.domain);
       int err;
       err = ub_resolve_async(s->resolver_ctx, srv_query, 33, 1,
                              s, rexmpp_srv_cb, NULL);
@@ -2037,7 +2025,7 @@ rexmpp_err_t rexmpp_run (rexmpp_t *s, fd_set *read_fds, fd_set *write_fds) {
                    srv_query, ub_strerror(err));
       }
       snprintf(srv_query, srv_query_buf_len,
-               "_xmpp-client._tcp.%s.", jid_bare_to_host(s->initial_jid));
+               "_xmpp-client._tcp.%s.", s->initial_jid.domain);
       err = ub_resolve_async(s->resolver_ctx, srv_query, 33, 1,
                              s, rexmpp_srv_cb, NULL);
       if (err) {
@@ -2104,7 +2092,7 @@ rexmpp_err_t rexmpp_run (rexmpp_t *s, fd_set *read_fds, fd_set *write_fds) {
       s->ping_requested = 1;
       xmlNodePtr ping_cmd = xmlNewNode(NULL, "ping");
       xmlNewNs(ping_cmd, "urn:xmpp:ping", NULL);
-      rexmpp_iq_new(s, "get", jid_bare_to_host(s->initial_jid),
+      rexmpp_iq_new(s, "get", s->initial_jid.domain,
                     ping_cmd, rexmpp_pong);
     } else {
       rexmpp_log(s, LOG_WARNING, "Ping timeout, reconnecting.");
diff --git a/src/rexmpp.h b/src/rexmpp.h
index 38cf4b2..8b5632a 100644
--- a/src/rexmpp.h
+++ b/src/rexmpp.h
@@ -17,7 +17,7 @@
 #include "rexmpp_tcp.h"
 #include "rexmpp_socks.h"
 #include "rexmpp_dns.h"
-
+#include "rexmpp_jid.h"
 
 typedef struct rexmpp rexmpp_t;
 
@@ -221,7 +221,7 @@ struct rexmpp
   enum carbons_st carbons_state;
 
   /* Basic configuration. */
-  char *initial_jid;
+  struct rexmpp_jid initial_jid;
 
   /* Manual host/port configuration. */
   const char *manual_host;
@@ -255,7 +255,7 @@ struct rexmpp
   roster_modify_cb_t roster_modify_cb;
 
   /* Stream-related state. */
-  char *assigned_jid;
+  struct rexmpp_jid assigned_jid;
   xmlNodePtr stream_features;
   xmlNodePtr roster_items;
   char *roster_ver;
diff --git a/src/rexmpp_jid.c b/src/rexmpp_jid.c
new file mode 100644
index 0000000..44e2754
--- /dev/null
+++ b/src/rexmpp_jid.c
@@ -0,0 +1,57 @@
+/**
+   @file rexmpp_jid.c
+   @brief JID parsing and manipulation
+   @author defanor <defanor@uberspace.net>
+   @date 2020
+   @copyright MIT license.
+*/
+
+#include <stddef.h>
+#include <string.h>
+#include "rexmpp_jid.h"
+
+int rexmpp_jid_parse (const char *str, struct rexmpp_jid *jid) {
+  const char *resource = NULL, *domain = NULL;
+  size_t i;
+  size_t resource_len = 0, local_len = 0;
+  size_t domain_len, bare_len, full_len = strlen(str);
+  domain_len = full_len;
+  bare_len = full_len;
+
+  /* Find the separators. */
+  for (i = 0; i < full_len; i++) {
+    if (local_len == 0 && str[i] == '@') {
+      local_len = i;
+      domain_len -= local_len + 1;
+      domain = str + i + 1;
+    }
+    if (str[i] == '/') {
+      resource_len = full_len - i - 1;
+      domain_len -= resource_len + 1;
+      bare_len -= resource_len + 1;
+      resource = str + i + 1;
+      break;
+    }
+  }
+
+  /* Check all the lengths. */
+  if (full_len > 3071 || bare_len > 2047 ||
+      local_len > 1023 || resource_len > 1023 ||
+      domain_len > 1023 || domain_len < 1) {
+    return -1;
+  }
+
+  /* Copy all the parts. */
+  strncpy(jid->full, str, full_len);
+  jid->full[full_len] = '\0';
+  strncpy(jid->bare, str, bare_len);
+  jid->bare[bare_len] = '\0';
+  strncpy(jid->local, str, local_len);
+  jid->local[local_len] = '\0';
+  strncpy(jid->domain, domain, domain_len);
+  jid->domain[domain_len] = '\0';
+  strncpy(jid->resource, resource, resource_len);
+  jid->resource[resource_len] = '\0';
+
+  return 0;
+}
diff --git a/src/rexmpp_jid.h b/src/rexmpp_jid.h
new file mode 100644
index 0000000..8613e3d
--- /dev/null
+++ b/src/rexmpp_jid.h
@@ -0,0 +1,24 @@
+/**
+   @file rexmpp_jid.h
+   @brief JID parsing and manipulation
+   @author defanor <defanor@uberspace.net>
+   @date 2020
+   @copyright MIT license.
+*/
+
+#ifndef REXMPP_JID_H
+#define REXMPP_JID_H
+
+/** @brief A redundant structure for easy access to JID parts and
+    avoidance of dynamic allocations. */
+struct rexmpp_jid {
+  char local[1024];
+  char domain[1024];
+  char resource[1024];
+  char bare[2048];
+  char full[3072];
+};
+
+int rexmpp_jid_parse (const char *str, struct rexmpp_jid *jid);
+
+#endif