Very basic group chats, tested and working with nTox.

Please wait until the tox.h API is updated before integrating it into
your clients.

nTox:
/g
creates a new group chat

/i friendnum groupnum
invite friendnum to groupnum

/z groupnum message
send message to groupnum

NOTE: group chats currenly might not handle packet loss well if there are less than 6 participants.

testing/nTox.c

@@ -348,13 +348,34 @@ void line_eval(Tox *m, char *line)
             do_refresh();
         } else if (inpt_command == 'h') { //help
             new_lines(help);
-        } else if (inpt_command == 'i') { //info
+        } else if (inpt_command == 'x') { //info
             char idstring[200];
             get_id(m, idstring);
             new_lines(idstring);
-        }
+        } else if (inpt_command == 'g') { //create new group chat
+            char msg[256];
+            sprintf(msg, "[g] Created new group chat with number: %u", add_groupchat(m));
+            new_lines(msg);
+        } else if (inpt_command == 'i') { //invite friendnum to groupnum
+            char *posi[1];
+            int friendnumber = strtoul(line + prompt_offset, posi, 0);
+            int groupnumber = strtoul(*posi + 1, NULL, 0);
+            char msg[256];
+            sprintf(msg, "[g] Invited friend number %u to group number %u, returned: %u (0 means success)", friendnumber,
+                    groupnumber, invite_friend(m, friendnumber, groupnumber));
+            new_lines(msg);
+        } else if (inpt_command == 'z') { //send message to groupnum
+            char *posi[1];
+            int groupnumber = strtoul(line + prompt_offset, posi, 0);
 
-        else if (inpt_command == 'q') { //exit
+            if (**posi != 0) {
+                char msg[256 + 1024];
+                sprintf(msg, "[g] sent message: %s to group num: %u returned: %u (0 means success)", *posi + 1, groupnumber,
+                        group_message_send(m, groupnumber, (uint8_t *)*posi + 1, strlen(*posi + 1) + 1));
+                new_lines(msg);
+            }
+
+        } else if (inpt_command == 'q') { //exit
             endwin();
             exit(EXIT_SUCCESS);
         } else {
@@ -535,6 +556,22 @@ void print_help(void)
     puts("\t-f\t-\tSpecify a keyfile to read (or write to) from.");
 }
 
+void print_invite(Messenger *m, int friendnumber, uint8_t *group_public_key, void *userdata)
+{
+    char msg[256];
+    sprintf(msg, "[i] recieved group chat invite from: %u, auto accepting and joining. group number: %u", friendnumber,
+            join_groupchat(m, friendnumber, group_public_key));
+    new_lines(msg);
+}
+
+void print_groupmessage(Messenger *m, int groupnumber, uint8_t *message, uint16_t length, void *userdata)
+{
+    char msg[256 + length];
+    sprintf(msg, "[g] %u: %s", groupnumber, message);
+    new_lines(msg);
+}
+
+
 int main(int argc, char *argv[])
 {
     int on = 0;
@@ -579,6 +616,8 @@ int main(int argc, char *argv[])
     tox_callback_friendmessage(m, print_message, NULL);
     tox_callback_namechange(m, print_nickchange, NULL);
     tox_callback_statusmessage(m, print_statuschange, NULL);
+    m_callback_group_invite(m, print_invite, NULL);
+    m_callback_group_message(m, print_groupmessage, NULL);
 
     initscr();
     noecho();

testing/nTox.h

@@ -31,7 +31,7 @@
 #include <ctype.h>
 
 #include "../toxcore/tox.h"
-
+#include "../toxcore/Messenger.h" //TODO: remove this
 #define STRING_LENGTH 256
 #define HISTORY 50
 #define PUB_KEY_BYTES 32

toxcore/Messenger.c

@@ -673,6 +673,40 @@ static int group_num(Messenger *m, uint8_t *group_public_key)
     return -1;
 }
 
+/* Set the callback for group invites.
+ *
+ *  Function(Messenger *m, int friendnumber, uint8_t *group_public_key, void *userdata)
+ */
+void m_callback_group_invite(Messenger *m, void (*function)(Messenger *m, int, uint8_t *, void *), void *userdata)
+{
+    m->group_invite = function;
+    m->group_invite_userdata = userdata;
+}
+
+/* Set the callback for group messages.
+ *
+ *  Function(Messenger *m, int groupnumber, uint8_t * message, uint16_t length, void *userdata)
+ */
+void m_callback_group_message(Messenger *m, void (*function)(Messenger *m, int, uint8_t *, uint16_t, void *),
+                              void *userdata)
+{
+    m->group_message = function;
+    m->group_message_userdata = userdata;
+}
+static void group_message_function(Group_Chat *chat, int peer_number, uint8_t *message, uint16_t length, void *userdata)
+{
+    Messenger *m = userdata;
+    uint32_t i;
+
+    for (i = 0; i < m->numchats; ++i) { //TODO: remove this
+        if (m->chats[i] == chat)
+            break;
+    }
+
+    if (m->group_message)
+        (*m->group_message)(m, i, message, length, m->group_invite_userdata);
+}
+
 /* Creates a new groupchat and puts it in the chats array.
  *
  * return group number on success.
@@ -689,6 +723,7 @@ int add_groupchat(Messenger *m)
             if (newchat == NULL)
                 return -1;
 
+            callback_groupmessage(newchat, &group_message_function, m);
             m->chats[i] = newchat;
             return i;
         }
@@ -705,6 +740,8 @@ int add_groupchat(Messenger *m)
     if (temp[m->numchats] == NULL)
         return -1;
 
+    m->chats = temp;
+    callback_groupmessage(temp[m->numchats], &group_message_function, m);
     ++m->numchats;
     return (m->numchats - 1);
 }
@@ -714,7 +751,7 @@ int add_groupchat(Messenger *m)
  * return 0 on success.
  * return -1 if failure.
  */
-static int del_groupchat(Messenger *m, int groupnumber)
+int del_groupchat(Messenger *m, int groupnumber)
 {
     if ((unsigned int)groupnumber >= m->numchats)
         return -1;
@@ -748,9 +785,42 @@ static int del_groupchat(Messenger *m, int groupnumber)
     return 0;
 }
 
+/* return 1 if that friend was invited to the group
+ * return 0 if the friend was not or error.
+ */
+static uint8_t group_invited(Messenger *m, int friendnumber, int groupnumber)
+{
+    //TODO: this function;
+    return 1;
+}
+
+/* invite friendnumber to groupnumber
+ * return 0 on success
+ * return -1 on failure
+ */
+int invite_friend(Messenger *m, int friendnumber, int groupnumber)
+{
+    if (friend_not_valid(m, friendnumber) || (unsigned int)groupnumber >= m->numchats)
+        return -1;
+
+    if (m->chats == NULL)
+        return -1;
+
+    if (m->friendlist[friendnumber].status == NOFRIEND || m->chats[groupnumber] == NULL)
+        return -1;
+
+    //TODO: store invited friends.
+    if (write_cryptpacket_id(m, friendnumber, PACKET_ID_INVITE_GROUPCHAT, m->chats[groupnumber]->self_public_key,
+                             crypto_box_PUBLICKEYBYTES) == 0)
+        return -1;
+
+    return 0;
+}
+
+
 /* Join a group (you need to have been invited first.)
  *
- * returns 0 on success
+ * returns group number on success
  * returns -1 on failure.
  */
 int join_groupchat(Messenger *m, int friendnumber, uint8_t *friend_group_public_key)
@@ -770,12 +840,34 @@ int join_groupchat(Messenger *m, int friendnumber, uint8_t *friend_group_public_
     if (write_cryptpacket_id(m, friendnumber, PACKET_ID_JOIN_GROUPCHAT, data, sizeof(data))) {
         chat_bootstrap_nonlazy(m->chats[groupnum], get_friend_ipport(m, friendnumber),
                                friend_group_public_key); //TODO: check if ip returned is zero?
-        return 0;
+        return groupnum;
     }
 
     return -1;
 }
 
+/* send a group message
+ * return 0 on success
+ * return -1 on failure
+ */
+
+int group_message_send(Messenger *m, int groupnumber, uint8_t *message, uint32_t length)
+{
+    if ((unsigned int)groupnumber >= m->numchats)
+        return -1;
+
+    if (m->chats == NULL)
+        return -1;
+
+    if (m->chats[groupnumber] == NULL)
+        return -1;
+
+    if (group_sendmessage(m->chats[groupnumber], message, length) > 0)
+        return 0;
+
+    return -1;
+}
+
 static int handle_group(void *object, IP_Port source, uint8_t *packet, uint32_t length)
 {
     Messenger *m = object;
@@ -1064,6 +1156,29 @@ void doFriends(Messenger *m)
 
                         break;
                     }
+
+                    case PACKET_ID_INVITE_GROUPCHAT: {
+                        if (data_length != crypto_box_PUBLICKEYBYTES)
+                            break;
+
+                        if (m->group_invite)
+                            (*m->group_invite)(m, i, data, m->group_invite_userdata);
+                    }
+
+                    case PACKET_ID_JOIN_GROUPCHAT: {
+                        if (data_length != crypto_box_PUBLICKEYBYTES * 2)
+                            break;
+
+                        int groupnum = group_num(m, data);
+
+                        if (groupnum == -1)
+                            break;
+
+                        if (!group_invited(m, i, groupnum))
+                            break;
+
+                        group_newpeer(m->chats[groupnum], data + crypto_box_PUBLICKEYBYTES);
+                    }
                 }
             } else {
                 if (is_cryptoconnected(m->net_crypto,

toxcore/Messenger.h

@@ -157,7 +157,10 @@ typedef struct Messenger {
     void *friend_statuschange_userdata;
     void (*friend_connectionstatuschange)(struct Messenger *m, int, uint8_t, void *);
     void *friend_connectionstatuschange_userdata;
-
+    void (*group_invite)(struct Messenger *m, int, uint8_t *, void *);
+    void *group_invite_userdata;
+    void (*group_message)(struct Messenger *m, int, uint8_t *, uint16_t, void *);
+    void *group_message_userdata;
 
 } Messenger;
 
@@ -369,6 +372,57 @@ void m_callback_read_receipt(Messenger *m, void (*function)(Messenger *m, int, u
  */
 void m_callback_connectionstatus(Messenger *m, void (*function)(Messenger *m, int, uint8_t, void *), void *userdata);
 
+/**********GROUP CHATS************/
+
+/* Set the callback for group invites.
+ *
+ *  Function(Messenger *m, int friendnumber, uint8_t *group_public_key, void *userdata)
+ */
+void m_callback_group_invite(Messenger *m, void (*function)(Messenger *m, int, uint8_t *, void *), void *userdata);
+
+/* Set the callback for group messages.
+ *
+ *  Function(Messenger *m, int groupnumber, uint8_t * message, uint16_t length, void *userdata)
+ */
+void m_callback_group_message(Messenger *m, void (*function)(Messenger *m, int, uint8_t *, uint16_t, void *),
+                              void *userdata);
+
+/* Creates a new groupchat and puts it in the chats array.
+ *
+ * return group number on success.
+ * return -1 on failure.
+ */
+int add_groupchat(Messenger *m);
+
+/* Delete a groupchat from the chats array.
+ *
+ * return 0 on success.
+ * return -1 if failure.
+ */
+int del_groupchat(Messenger *m, int groupnumber);
+
+/* invite friendnumber to groupnumber
+ * return 0 on success
+ * return -1 on failure
+ */
+int invite_friend(Messenger *m, int friendnumber, int groupnumber);
+
+/* Join a group (you need to have been invited first.)
+ *
+ * returns group number on success
+ * returns -1 on failure.
+ */
+int join_groupchat(Messenger *m, int friendnumber, uint8_t *friend_group_public_key);
+
+/* send a group message
+ * return 0 on success
+ * return -1 on failure
+ */
+
+int group_message_send(Messenger *m, int groupnumber, uint8_t *message, uint32_t length);
+
+/*********************************/
+
 /* Run this at startup.
  *  return allocated instance of Messenger on success.
  *  return 0 if there are problems.

toxcore/group_chats.h

@@ -77,6 +77,7 @@ void callback_groupmessage(Group_Chat *chat, void (*function)(Group_Chat *chat,
 /*
  * Send a message to the group.
  *
+ * returns the number of peers it has sent it to.
  */
 uint32_t group_sendmessage(Group_Chat *chat, uint8_t *message, uint32_t length);