1 files changed, 59 insertions, 6 deletions

diff --git a/core/Messenger.c b/core/Messenger.c
index 3ad9097c..f1d8b35e 100644
--- a/core/Messenger.c
+++ b/core/Messenger.c
@@ -38,6 +38,8 @@ typedef struct {
     USERSTATUS userstatus;
     uint8_t userstatus_sent;
     uint16_t info_size; /* length of the info */
+    uint32_t message_id; /* a semi-unique id used in read receipts */
+    uint8_t receives_read_receipts; /* shall we send read receipts to this person? */
 } Friend;
 
 uint8_t self_public_key[crypto_box_PUBLICKEYBYTES];
@@ -129,6 +131,8 @@ int m_addfriend(uint8_t *client_id, uint8_t *data, uint16_t length)
             friendlist[i].userstatus = USERSTATUS_NONE;
             memcpy(friendlist[i].info, data, length);
             friendlist[i].info_size = length;
+            friendlist[i].message_id = 0;
+            friendlist[i].receives_read_receipts = 1; /* default: YES */
 
             ++numfriends;
             return i;
@@ -152,6 +156,8 @@ int m_addfriend_norequest(uint8_t * client_id)
             friendlist[i].statusmessage = calloc(1, 1);
             friendlist[i].statusmessage_length = 1;
             friendlist[i].userstatus = USERSTATUS_NONE;
+            friendlist[i].message_id = 0;
+            friendlist[i].receives_read_receipts = 1; /* default: YES */
             numfriends++;
             return i;
         }
@@ -195,19 +201,31 @@ int m_friendstatus(int friendnumber)
 }
 
 /* send a text chat message to an online friend
-   return 1 if packet was successfully put into the send queue
+   return the message id if packet was successfully put into the send queue
    return 0 if it was not */
-int m_sendmessage(int friendnumber, uint8_t *message, uint32_t length)
+uint32_t m_sendmessage(int friendnumber, uint8_t *message, uint32_t length)
 {
     if (friendnumber < 0 || friendnumber >= numfriends)
         return 0;
-    if (length >= MAX_DATA_SIZE || friendlist[friendnumber].status != FRIEND_ONLINE)
+    uint32_t msgid = ++friendlist[friendnumber].message_id;
+    if (msgid == 0)
+        msgid = 1; /* otherwise, false error */
+    return m_sendmessage_withid(friendnumber, msgid, message, length);
+}
+
+uint32_t m_sendmessage_withid(int friendnumber, uint32_t theid, uint8_t *message, uint32_t length)
+{
+    if (friendnumber < 0 || friendnumber >= numfriends)
+        return 0;
+    if (length >= (MAX_DATA_SIZE - sizeof(theid)) || friendlist[friendnumber].status != FRIEND_ONLINE)
         /* this does not mean the maximum message length is MAX_DATA_SIZE - 1, it is actually 17 bytes less. */
         return 0;
     uint8_t temp[MAX_DATA_SIZE];
     temp[0] = PACKET_ID_MESSAGE;
-    memcpy(temp + 1, message, length);
-    return write_cryptpacket(friendlist[friendnumber].crypt_connection_id, temp, length + 1);
+    theid = htonl(theid);
+    memcpy(temp + 1, &theid, sizeof(theid));
+    memcpy(temp + 1 + sizeof(theid), message, length);
+    return write_cryptpacket(friendlist[friendnumber].crypt_connection_id, temp, length + 1 + sizeof(theid));
 }
 
 /* send a name packet to friendnumber
@@ -382,6 +400,16 @@ static void set_friend_userstatus(int friendnumber, USERSTATUS status)
     friendlist[friendnumber].userstatus = status;
 }
 
+/* Sets whether we send read receipts for friendnumber. */
+void m_set_sends_receipts(int friendnumber, int yesno)
+{
+    if (yesno != 0 || yesno != 1)
+        return;
+    if (friendnumber >= numfriends || friendnumber < 0)
+        return;
+    friendlist[friendnumber].receives_read_receipts = yesno;
+}
+
 /* static void (*friend_request)(uint8_t *, uint8_t *, uint16_t);
 static uint8_t friend_request_isset = 0; */
 /* set the function that will be executed when a friend request is received. */
@@ -424,6 +452,14 @@ void m_callback_userstatus(void (*function)(int, USERSTATUS))
     friend_userstatuschange_isset = 1;
 }
 
+static void (*read_receipt)(int, uint32_t);
+static uint8_t read_receipt_isset = 0;
+void m_callback_read_receipt(void (*function)(int, uint32_t))
+{
+    read_receipt = function;
+    read_receipt_isset = 1;
+}
+
 #define PORT 33445
 /* run this at startup */
 int initMessenger(void)
@@ -521,8 +557,25 @@ static void doFriends(void)
                     break;
                 }
                 case PACKET_ID_MESSAGE: {
+                    if (friendlist[i].receives_read_receipts) {
+                        uint8_t *thepacket = malloc(5);
+                        thepacket[0] = PACKET_ID_RECEIPT;
+                        memcpy(thepacket + 1, temp + 1, 4);
+                        write_cryptpacket(friendlist[i].crypt_connection_id, thepacket, 5);
+                        free(thepacket);
+                    }
                     if (friend_message_isset)
-                        (*friend_message)(i, temp + 1, len - 1);
+                        (*friend_message)(i, temp + 5, len - 5);
+                    break;
+                }
+                case PACKET_ID_RECEIPT: {
+                    uint32_t msgid;
+                    if (len < 1 + sizeof(msgid))
+                        break;
+                    memcpy(&msgid, temp + 1, sizeof(msgid));
+                    msgid = ntohl(msgid);
+                    if (read_receipt_isset)
+                        (*read_receipt)(i, msgid);
                     break;
                 }
                 }