diff --git a/toxcore/DHT.c b/toxcore/DHT.c
index 1055ddcd..ae61d988 100644
--- a/toxcore/DHT.c
+++ b/toxcore/DHT.c
@@ -1067,7 +1067,7 @@ static int sendnodes_ipv6(const DHT *dht, IP_Port ip_port, const uint8_t *public
     return sendpacket(dht->net, ip_port, data, 1 + CLIENT_ID_SIZE + crypto_box_NONCEBYTES + len);
 }
 
-static int handle_getnodes(void *object, IP_Port source, uint8_t *packet, uint32_t length)
+static int handle_getnodes(void *object, IP_Port source, const uint8_t *packet, uint32_t length)
 {
     uint32_t cmp_len = 1 + CLIENT_ID_SIZE + crypto_box_NONCEBYTES + CLIENT_ID_SIZE + crypto_box_MACBYTES;
 
@@ -1194,7 +1194,7 @@ static int handle_sendnodes_core(void *object, IP_Port source, const uint8_t *pa
     return 0;
 }
 
-static int handle_sendnodes_ipv6(void *object, IP_Port source, uint8_t *packet, uint32_t length)
+static int handle_sendnodes_ipv6(void *object, IP_Port source, const uint8_t *packet, uint32_t length)
 {
     DHT *dht = object;
     Node_format plain_nodes[MAX_SENT_NODES];
@@ -2296,7 +2296,7 @@ void cryptopacket_registerhandler(DHT *dht, uint8_t byte, cryptopacket_handler_c
     dht->cryptopackethandlers[byte].object = object;
 }
 
-static int cryptopacket_handle(void *object, IP_Port source, uint8_t *packet, uint32_t length)
+static int cryptopacket_handle(void *object, IP_Port source, const uint8_t *packet, uint32_t length)
 {
     DHT *dht = object;
 
diff --git a/toxcore/LAN_discovery.c b/toxcore/LAN_discovery.c
index 2deeadfd..e1b8534c 100644
--- a/toxcore/LAN_discovery.c
+++ b/toxcore/LAN_discovery.c
@@ -98,7 +98,7 @@ static void fetch_broadcast_info(uint16_t port)
  *  return 1 if sent to at least one broadcast target.
  *  return 0 on failure to find any valid broadcast target.
  */
-static uint32_t send_broadcasts(Networking_Core *net, uint16_t port, uint8_t *data, uint16_t length)
+static uint32_t send_broadcasts(Networking_Core *net, uint16_t port, const uint8_t *data, uint16_t length)
 {
     /* fetch only once? on every packet? every X seconds?
      * old: every packet, new: once */
@@ -207,7 +207,7 @@ int LAN_ip(IP ip)
     return -1;
 }
 
-static int handle_LANdiscovery(void *object, IP_Port source, uint8_t *packet, uint32_t length)
+static int handle_LANdiscovery(void *object, IP_Port source, const uint8_t *packet, uint32_t length)
 {
     DHT *dht = object;
 
diff --git a/toxcore/Messenger.c b/toxcore/Messenger.c
index 37a7a252..dc8db8b3 100644
--- a/toxcore/Messenger.c
+++ b/toxcore/Messenger.c
@@ -1261,7 +1261,7 @@ int group_names(Messenger *m, int groupnumber, uint8_t names[][MAX_NICK_BYTES],
     return group_client_names(m->chats[groupnumber], names, lengths, length);
 }
 
-static int handle_group(void *object, IP_Port source, uint8_t *packet, uint32_t length)
+static int handle_group(void *object, IP_Port source, const uint8_t *packet, uint32_t length)
 {
     Messenger *m = object;
 
diff --git a/toxcore/TCP_server.c b/toxcore/TCP_server.c
index d055215e..b900db6b 100644
--- a/toxcore/TCP_server.c
+++ b/toxcore/TCP_server.c
@@ -619,7 +619,7 @@ static int rm_connection_index(TCP_Server *TCP_server, TCP_Secure_Connection *co
     }
 }
 
-static int handle_onion_recv_1(void *object, IP_Port dest, uint8_t *data, uint16_t length)
+static int handle_onion_recv_1(void *object, IP_Port dest, const uint8_t *data, uint16_t length)
 {
     TCP_Server *TCP_server = object;
     uint32_t index = dest.ip.ip6.uint32[0];
diff --git a/toxcore/net_crypto.c b/toxcore/net_crypto.c
index 78a6121c..c34c24d7 100644
--- a/toxcore/net_crypto.c
+++ b/toxcore/net_crypto.c
@@ -120,7 +120,7 @@ static int create_cookie(uint8_t *cookie, uint8_t *bytes, uint8_t *encryption_ke
  * return -1 on failure.
  * return 0 on success.
  */
-static int open_cookie(uint8_t *bytes, uint8_t *cookie, uint8_t *encryption_key)
+static int open_cookie(uint8_t *bytes, const uint8_t *cookie, const uint8_t *encryption_key)
 {
     uint8_t contents[COOKIE_CONTENTS_LENGTH];
     int len = decrypt_data_symmetric(encryption_key, cookie, cookie + crypto_box_NONCEBYTES,
@@ -178,7 +178,7 @@ static int create_cookie_response(Net_Crypto *c, uint8_t *packet, uint8_t *reque
  * return 0 on success.
  */
 static int handle_cookie_request(Net_Crypto *c, uint8_t *request_plain, uint8_t *shared_key, uint8_t *dht_public_key,
-                                 uint8_t *packet, uint16_t length)
+                                 const uint8_t *packet, uint16_t length)
 {
     if (length != COOKIE_REQUEST_LENGTH)
         return -1;
@@ -197,7 +197,7 @@ static int handle_cookie_request(Net_Crypto *c, uint8_t *request_plain, uint8_t
 
 /* Handle the cookie request packet (for raw UDP)
  */
-static int udp_handle_cookie_request(void *object, IP_Port source, uint8_t *packet, uint32_t length)
+static int udp_handle_cookie_request(void *object, IP_Port source, const uint8_t *packet, uint32_t length)
 {
     Net_Crypto *c = object;
     uint8_t request_plain[COOKIE_REQUEST_PLAIN_LENGTH];
@@ -275,8 +275,8 @@ static int tcp_oob_handle_cookie_request(Net_Crypto *c, TCP_Client_Connection *T
  * return -1 on failure.
  * return COOKIE_LENGTH on success.
  */
-static int handle_cookie_response(uint8_t *cookie, uint64_t *number, uint8_t *packet, uint32_t length,
-                                  uint8_t *shared_key)
+static int handle_cookie_response(uint8_t *cookie, uint64_t *number, const uint8_t *packet, uint32_t length,
+                                  const uint8_t *shared_key)
 {
     if (length != COOKIE_RESPONSE_LENGTH)
         return -1;
@@ -349,7 +349,7 @@ static int create_crypto_handshake(Net_Crypto *c, uint8_t *packet, uint8_t *cook
  * return 0 on success.
  */
 static int handle_crypto_handshake(Net_Crypto *c, uint8_t *nonce, uint8_t *session_pk, uint8_t *peer_real_pk,
-                                   uint8_t *dht_public_key, uint8_t *cookie, uint8_t *packet, uint32_t length, uint8_t *expected_real_pk)
+                                   uint8_t *dht_public_key, uint8_t *cookie, const uint8_t *packet, uint32_t length, uint8_t *expected_real_pk)
 {
     if (length != HANDSHAKE_PACKET_LENGTH)
         return -1;
@@ -815,7 +815,7 @@ static uint16_t get_nonce_uint16(uint8_t *nonce)
  * return -1 on failure.
  * return length of data on success.
  */
-static int handle_data_packet(Net_Crypto *c, int crypt_connection_id, uint8_t *data, uint8_t *packet, uint16_t length)
+static int handle_data_packet(Net_Crypto *c, int crypt_connection_id, uint8_t *data, const uint8_t *packet, uint16_t length)
 {
     if (length <= (1 + sizeof(uint16_t) + crypto_box_MACBYTES) || length > MAX_CRYPTO_PACKET_SIZE)
         return -1;
@@ -1039,7 +1039,7 @@ static int send_kill_packet(Net_Crypto *c, int crypt_connection_id)
  * return -1 on failure.
  * return 0 on success.
  */
-static int handle_data_packet_helper(Net_Crypto *c, int crypt_connection_id, uint8_t *packet, uint16_t length)
+static int handle_data_packet_helper(Net_Crypto *c, int crypt_connection_id, const uint8_t *packet, uint16_t length)
 {
     if (length > MAX_CRYPTO_PACKET_SIZE || length <= CRYPTO_DATA_PACKET_MIN_SIZE)
         return -1;
@@ -1133,7 +1133,7 @@ static int handle_data_packet_helper(Net_Crypto *c, int crypt_connection_id, uin
  * return -1 on failure.
  * return 0 on success.
  */
-static int handle_packet_connection(Net_Crypto *c, int crypt_connection_id, uint8_t *packet, uint16_t length)
+static int handle_packet_connection(Net_Crypto *c, int crypt_connection_id, const uint8_t *packet, uint16_t length)
 {
     if (length == 0 || length > MAX_CRYPTO_PACKET_SIZE)
         return -1;
@@ -1370,7 +1370,7 @@ void new_connection_handler(Net_Crypto *c, int (*new_connection_callback)(void *
  * return -1 on failure.
  * return 0 on success.
  */
-static int handle_new_connection_handshake(Net_Crypto *c, IP_Port source, uint8_t *data, uint16_t length)
+static int handle_new_connection_handshake(Net_Crypto *c, IP_Port source, const uint8_t *data, uint16_t length)
 {
     New_Connection n_c;
     n_c.cookie = malloc(COOKIE_LENGTH);
@@ -2123,7 +2123,7 @@ static int crypto_id_ip_port(Net_Crypto *c, IP_Port ip_port)
  * Crypto data packets.
  *
  */
-static int udp_handle_packet(void *object, IP_Port source, uint8_t *packet, uint32_t length)
+static int udp_handle_packet(void *object, IP_Port source, const uint8_t *packet, uint32_t length)
 {
     if (length <= CRYPTO_MIN_PACKET_SIZE || length > MAX_CRYPTO_PACKET_SIZE)
         return 1;
diff --git a/toxcore/network.h b/toxcore/network.h
index e5c24a2d..359d26c8 100644
--- a/toxcore/network.h
+++ b/toxcore/network.h
@@ -270,7 +270,7 @@ int addr_resolve_or_parse_ip(const char *address, IP *to, IP *extra);
  * Packet data is put into data.
  * Packet length is put into length.
  */
-typedef int (*packet_handler_callback)(void *object, IP_Port ip_port, uint8_t *data, uint32_t len);
+typedef int (*packet_handler_callback)(void *object, IP_Port ip_port, const uint8_t *data, uint32_t len);
 
 typedef struct {
     packet_handler_callback function;
diff --git a/toxcore/onion.c b/toxcore/onion.c
index 479c6209..194178f3 100644
--- a/toxcore/onion.c
+++ b/toxcore/onion.c
@@ -149,7 +149,7 @@ int send_onion_packet(Networking_Core *net, Onion_Path *path, IP_Port dest, uint
  * return -1 on failure.
  * return 0 on success.
  */
-int send_onion_response(Networking_Core *net, IP_Port dest, uint8_t *data, uint32_t length, uint8_t *ret)
+int send_onion_response(Networking_Core *net, IP_Port dest, const uint8_t *data, uint32_t length, const uint8_t *ret)
 {
     if (length > ONION_RESPONSE_MAX_DATA_SIZE || length == 0)
         return -1;
@@ -165,7 +165,7 @@ int send_onion_response(Networking_Core *net, IP_Port dest, uint8_t *data, uint3
     return 0;
 }
 
-static int handle_send_initial(void *object, IP_Port source, uint8_t *packet, uint32_t length)
+static int handle_send_initial(void *object, IP_Port source, const uint8_t *packet, uint32_t length)
 {
     Onion *onion = object;
 
@@ -189,7 +189,7 @@ static int handle_send_initial(void *object, IP_Port source, uint8_t *packet, ui
     return onion_send_1(onion, plain, len, source, packet + 1);
 }
 
-int onion_send_1(Onion *onion, uint8_t *plain, uint32_t len, IP_Port source, uint8_t *nonce)
+int onion_send_1(Onion *onion, uint8_t *plain, uint32_t len, IP_Port source, const uint8_t *nonce)
 {
     IP_Port send_to;
     ipport_unpack(&send_to, plain);
@@ -219,7 +219,7 @@ int onion_send_1(Onion *onion, uint8_t *plain, uint32_t len, IP_Port source, uin
     return 0;
 }
 
-static int handle_send_1(void *object, IP_Port source, uint8_t *packet, uint32_t length)
+static int handle_send_1(void *object, IP_Port source, const uint8_t *packet, uint32_t length)
 {
     Onion *onion = object;
 
@@ -268,7 +268,7 @@ static int handle_send_1(void *object, IP_Port source, uint8_t *packet, uint32_t
     return 0;
 }
 
-static int handle_send_2(void *object, IP_Port source, uint8_t *packet, uint32_t length)
+static int handle_send_2(void *object, IP_Port source, const uint8_t *packet, uint32_t length)
 {
     Onion *onion = object;
 
@@ -316,7 +316,7 @@ static int handle_send_2(void *object, IP_Port source, uint8_t *packet, uint32_t
 }
 
 
-static int handle_recv_3(void *object, IP_Port source, uint8_t *packet, uint32_t length)
+static int handle_recv_3(void *object, IP_Port source, const uint8_t *packet, uint32_t length)
 {
     Onion *onion = object;
 
@@ -350,7 +350,7 @@ static int handle_recv_3(void *object, IP_Port source, uint8_t *packet, uint32_t
     return 0;
 }
 
-static int handle_recv_2(void *object, IP_Port source, uint8_t *packet, uint32_t length)
+static int handle_recv_2(void *object, IP_Port source, const uint8_t *packet, uint32_t length)
 {
     Onion *onion = object;
 
@@ -384,7 +384,7 @@ static int handle_recv_2(void *object, IP_Port source, uint8_t *packet, uint32_t
     return 0;
 }
 
-static int handle_recv_1(void *object, IP_Port source, uint8_t *packet, uint32_t length)
+static int handle_recv_1(void *object, IP_Port source, const uint8_t *packet, uint32_t length)
 {
     Onion *onion = object;
 
@@ -417,7 +417,7 @@ static int handle_recv_1(void *object, IP_Port source, uint8_t *packet, uint32_t
     return 0;
 }
 
-void set_callback_handle_recv_1(Onion *onion, int (*function)(void *, IP_Port, uint8_t *, uint16_t), void *object)
+void set_callback_handle_recv_1(Onion *onion, int (*function)(void *, IP_Port, const uint8_t *, uint16_t), void *object)
 {
     onion->recv_1_function = function;
     onion->callback_object = object;
diff --git a/toxcore/onion.h b/toxcore/onion.h
index 13dc8f52..07d5b6d9 100644
--- a/toxcore/onion.h
+++ b/toxcore/onion.h
@@ -35,7 +35,7 @@ typedef struct {
     Shared_Keys shared_keys_2;
     Shared_Keys shared_keys_3;
 
-    int (*recv_1_function)(void *, IP_Port, uint8_t *, uint16_t);
+    int (*recv_1_function)(void *, IP_Port, const uint8_t *, uint16_t);
     void *callback_object;
 } Onion;
 
@@ -94,7 +94,7 @@ int send_onion_packet(Networking_Core *net, Onion_Path *path, IP_Port dest, uint
  * return -1 on failure.
  * return 0 on success.
  */
-int send_onion_response(Networking_Core *net, IP_Port dest, uint8_t *data, uint32_t length, uint8_t *ret);
+int send_onion_response(Networking_Core *net, IP_Port dest, const uint8_t *data, uint32_t length, const uint8_t *ret);
 
 /* Function to handle/send received decrypted versions of the packet sent with send_onion_packet.
  *
@@ -106,13 +106,13 @@ int send_onion_response(Networking_Core *net, IP_Port dest, uint8_t *data, uint3
  * Source family must be set to something else than AF_INET6 or AF_INET so that the callback gets called
  * when the response is received.
  */
-int onion_send_1(Onion *onion, uint8_t *plain, uint32_t len, IP_Port source, uint8_t *nonce);
+int onion_send_1(Onion *onion, uint8_t *plain, uint32_t len, IP_Port source, const uint8_t *nonce);
 
 /* Set the callback to be called when the dest ip_port doesn't have AF_INET6 or AF_INET as the family.
  *
  * Format: function(void *object, IP_Port dest, uint8_t *data, uint32_t length)
  */
-void set_callback_handle_recv_1(Onion *onion, int (*function)(void *, IP_Port, uint8_t *, uint16_t), void *object);
+void set_callback_handle_recv_1(Onion *onion, int (*function)(void *, IP_Port, const uint8_t *, uint16_t), void *object);
 
 Onion *new_onion(DHT *dht);
 
diff --git a/toxcore/onion_announce.c b/toxcore/onion_announce.c
index a9891b9c..a8f71a4e 100644
--- a/toxcore/onion_announce.c
+++ b/toxcore/onion_announce.c
@@ -115,7 +115,7 @@ int send_data_request(Networking_Core *net, Onion_Path *path, IP_Port dest, uint
 }
 
 /* Generate a ping_id and put it in ping_id */
-static void generate_ping_id(Onion_Announce *onion_a, uint64_t time, uint8_t *public_key, IP_Port ret_ip_port,
+static void generate_ping_id(Onion_Announce *onion_a, uint64_t time, const uint8_t *public_key, IP_Port ret_ip_port,
                              uint8_t *ping_id)
 {
     time /= PING_ID_TIMEOUT;
@@ -132,7 +132,7 @@ static void generate_ping_id(Onion_Announce *onion_a, uint64_t time, uint8_t *pu
  * return -1 if no
  * return position in list if yes
  */
-static int in_entries(Onion_Announce *onion_a, uint8_t *public_key)
+static int in_entries(const Onion_Announce *onion_a, const uint8_t *public_key)
 {
     uint32_t i;
 
@@ -179,8 +179,8 @@ static int cmp_entry(const void *a, const void *b)
  * return -1 if failure
  * return position if added
  */
-static int add_to_entries(Onion_Announce *onion_a, IP_Port ret_ip_port, uint8_t *public_key, uint8_t *data_public_key,
-                          uint8_t *ret)
+static int add_to_entries(Onion_Announce *onion_a, IP_Port ret_ip_port, const uint8_t *public_key, const uint8_t *data_public_key,
+                          const uint8_t *ret)
 {
 
     int pos = in_entries(onion_a, public_key);
@@ -213,14 +213,14 @@ static int add_to_entries(Onion_Announce *onion_a, IP_Port ret_ip_port, uint8_t
     return in_entries(onion_a, public_key);
 }
 
-static int handle_announce_request(void *object, IP_Port source, uint8_t *packet, uint32_t length)
+static int handle_announce_request(void *object, IP_Port source, const uint8_t *packet, uint32_t length)
 {
     Onion_Announce *onion_a = object;
 
     if (length != ANNOUNCE_REQUEST_SIZE_RECV)
         return 1;
 
-    uint8_t *packet_public_key = packet + 1 + crypto_box_NONCEBYTES;
+    const uint8_t *packet_public_key = packet + 1 + crypto_box_NONCEBYTES;
     uint8_t shared_key[crypto_box_BEFORENMBYTES];
     get_shared_key(&onion_a->shared_keys_recv, shared_key, onion_a->dht->self_secret_key, packet_public_key);
 
@@ -302,7 +302,7 @@ static int handle_announce_request(void *object, IP_Port source, uint8_t *packet
     return 0;
 }
 
-static int handle_data_request(void *object, IP_Port source, uint8_t *packet, uint32_t length)
+static int handle_data_request(void *object, IP_Port source, const uint8_t *packet, uint32_t length)
 {
     Onion_Announce *onion_a = object;
 
diff --git a/toxcore/onion_client.c b/toxcore/onion_client.c
index 630882cc..ae5e8810 100644
--- a/toxcore/onion_client.c
+++ b/toxcore/onion_client.c
@@ -164,7 +164,7 @@ static int new_sendback(Onion_Client *onion_c, uint32_t num, uint8_t *public_key
  * return ~0 on failure
  * return num (see new_sendback(...)) on success
  */
-static uint32_t check_sendback(Onion_Client *onion_c, uint8_t *sendback, uint8_t *ret_pubkey, IP_Port *ret_ip_port)
+static uint32_t check_sendback(Onion_Client *onion_c, const uint8_t *sendback, uint8_t *ret_pubkey, IP_Port *ret_ip_port)
 {
     uint64_t sback;
     memcpy(&sback, sendback, sizeof(uint64_t));
@@ -377,7 +377,7 @@ static int client_ping_nodes(Onion_Client *onion_c, uint32_t num, Node_format *n
     return 0;
 }
 
-static int handle_announce_response(void *object, IP_Port source, uint8_t *packet, uint32_t length)
+static int handle_announce_response(void *object, IP_Port source, const uint8_t *packet, uint32_t length)
 {
     Onion_Client *onion_c = object;
 
@@ -432,7 +432,7 @@ static int handle_announce_response(void *object, IP_Port source, uint8_t *packe
 
 #define DATA_IN_RESPONSE_MIN_SIZE ONION_DATA_IN_RESPONSE_MIN_SIZE
 
-static int handle_data_response(void *object, IP_Port source, uint8_t *packet, uint32_t length)
+static int handle_data_response(void *object, IP_Port source, const uint8_t *packet, uint32_t length)
 {
     Onion_Client *onion_c = object;
 
diff --git a/toxcore/ping.c b/toxcore/ping.c
index ea8fd04d..e00036af 100644
--- a/toxcore/ping.c
+++ b/toxcore/ping.c
@@ -129,7 +129,7 @@ static int send_ping_response(PING *ping, IP_Port ipp, const uint8_t *client_id,
     return sendpacket(ping->dht->net, ipp, pk, sizeof(pk));
 }
 
-static int handle_ping_request(void *_dht, IP_Port source, uint8_t *packet, uint32_t length)
+static int handle_ping_request(void *_dht, IP_Port source, const uint8_t *packet, uint32_t length)
 {
     DHT       *dht = _dht;
     int        rc;
@@ -168,7 +168,7 @@ static int handle_ping_request(void *_dht, IP_Port source, uint8_t *packet, uint
     return 0;
 }
 
-static int handle_ping_response(void *_dht, IP_Port source, uint8_t *packet, uint32_t length)
+static int handle_ping_response(void *_dht, IP_Port source, const uint8_t *packet, uint32_t length)
 {
     DHT      *dht = _dht;
     int       rc;