diff --git a/appveyor.yml b/appveyor.yml
index 91f727f7..c921d761 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -10,7 +10,7 @@ install:
 - cd third_party
 # libsodium
 - mkdir libsodium && cd libsodium
-- if not exist %APPDATA%\downloads\libsodium.zip curl -L https://download.libsodium.org/libsodium/releases/libsodium-1.0.12-msvc.zip -o %APPDATA%\downloads\libsodium.zip
+- if not exist %APPDATA%\downloads\libsodium.zip curl -L https://download.libsodium.org/libsodium/releases/libsodium-1.0.16-msvc.zip -o %APPDATA%\downloads\libsodium.zip
 - unzip %APPDATA%\downloads\libsodium.zip
 - cd ..
 # pthreads-win32
diff --git a/auto_tests/TCP_test.c b/auto_tests/TCP_test.c
index 144d7e14..41125116 100644
--- a/auto_tests/TCP_test.c
+++ b/auto_tests/TCP_test.c
@@ -83,14 +83,14 @@ START_TEST(test_basic)
                        TCP_HANDSHAKE_PLAIN_SIZE, handshake + CRYPTO_PUBLIC_KEY_SIZE + CRYPTO_NONCE_SIZE);
     ck_assert_msg(ret == TCP_CLIENT_HANDSHAKE_SIZE - (CRYPTO_PUBLIC_KEY_SIZE + CRYPTO_NONCE_SIZE),
                   "Encrypt failed.");
-    ck_assert_msg(send(sock, (const char *)handshake, TCP_CLIENT_HANDSHAKE_SIZE - 1, 0) == TCP_CLIENT_HANDSHAKE_SIZE - 1,
+    ck_assert_msg(net_send(sock, handshake, TCP_CLIENT_HANDSHAKE_SIZE - 1) == TCP_CLIENT_HANDSHAKE_SIZE - 1,
                   "send Failed.");
     c_sleep(50);
     do_TCP_server(tcp_s);
     c_sleep(50);
     do_TCP_server(tcp_s);
     c_sleep(50);
-    ck_assert_msg(send(sock, (const char *)(handshake + (TCP_CLIENT_HANDSHAKE_SIZE - 1)), 1, 0) == 1, "send Failed.");
+    ck_assert_msg(net_send(sock, handshake + (TCP_CLIENT_HANDSHAKE_SIZE - 1), 1) == 1, "send Failed.");
     c_sleep(50);
     do_TCP_server(tcp_s);
     c_sleep(50);
@@ -98,7 +98,7 @@ START_TEST(test_basic)
     c_sleep(50);
     uint8_t response[TCP_SERVER_HANDSHAKE_SIZE];
     uint8_t response_plain[TCP_HANDSHAKE_PLAIN_SIZE];
-    ck_assert_msg(recv(sock, (char *)response, TCP_SERVER_HANDSHAKE_SIZE, 0) == TCP_SERVER_HANDSHAKE_SIZE, "recv Failed.");
+    ck_assert_msg(net_recv(sock, response, TCP_SERVER_HANDSHAKE_SIZE) == TCP_SERVER_HANDSHAKE_SIZE, "recv Failed.");
     ret = decrypt_data(self_public_key, f_secret_key, response, response + CRYPTO_NONCE_SIZE,
                        TCP_SERVER_HANDSHAKE_SIZE - CRYPTO_NONCE_SIZE, response_plain);
     ck_assert_msg(ret == TCP_HANDSHAKE_PLAIN_SIZE, "Decrypt Failed.");
@@ -118,8 +118,10 @@ START_TEST(test_basic)
     uint32_t i;
 
     for (i = 0; i < sizeof(r_req); ++i) {
-        ck_assert_msg(send(sock, (const char *)(r_req + i), 1, 0) == 1, "send Failed.");
-        //ck_assert_msg(send(sock, (const char *)r_req, sizeof(r_req), 0) == sizeof(r_req), "send Failed.");
+        ck_assert_msg(net_send(sock, r_req + i, 1) == 1, "send Failed.");
+#if 0
+        ck_assert_msg(net_send(sock, r_req, sizeof(r_req)) == sizeof(r_req), "send Failed.");
+#endif
         do_TCP_server(tcp_s);
         c_sleep(50);
     }
@@ -127,7 +129,7 @@ START_TEST(test_basic)
     do_TCP_server(tcp_s);
     c_sleep(50);
     uint8_t packet_resp[4096];
-    int recv_data_len = recv(sock, (char *)packet_resp, 2 + 2 + CRYPTO_PUBLIC_KEY_SIZE + CRYPTO_MAC_SIZE, 0);
+    int recv_data_len = net_recv(sock, packet_resp, 2 + 2 + CRYPTO_PUBLIC_KEY_SIZE + CRYPTO_MAC_SIZE);
     ck_assert_msg(recv_data_len == 2 + 2 + CRYPTO_PUBLIC_KEY_SIZE + CRYPTO_MAC_SIZE,
                   "recv Failed. %u", recv_data_len);
     memcpy(&size, packet_resp, 2);
@@ -180,16 +182,16 @@ static struct sec_TCP_con *new_TCP_con(TCP_Server *tcp_s)
                        TCP_HANDSHAKE_PLAIN_SIZE, handshake + CRYPTO_PUBLIC_KEY_SIZE + CRYPTO_NONCE_SIZE);
     ck_assert_msg(ret == TCP_CLIENT_HANDSHAKE_SIZE - (CRYPTO_PUBLIC_KEY_SIZE + CRYPTO_NONCE_SIZE),
                   "Encrypt failed.");
-    ck_assert_msg(send(sock, (const char *)handshake, TCP_CLIENT_HANDSHAKE_SIZE - 1, 0) == TCP_CLIENT_HANDSHAKE_SIZE - 1,
+    ck_assert_msg(net_send(sock, handshake, TCP_CLIENT_HANDSHAKE_SIZE - 1) == TCP_CLIENT_HANDSHAKE_SIZE - 1,
                   "send Failed.");
     do_TCP_server(tcp_s);
     c_sleep(50);
-    ck_assert_msg(send(sock, (const char *)(handshake + (TCP_CLIENT_HANDSHAKE_SIZE - 1)), 1, 0) == 1, "send Failed.");
+    ck_assert_msg(net_send(sock, handshake + (TCP_CLIENT_HANDSHAKE_SIZE - 1), 1) == 1, "send Failed.");
     c_sleep(50);
     do_TCP_server(tcp_s);
     uint8_t response[TCP_SERVER_HANDSHAKE_SIZE];
     uint8_t response_plain[TCP_HANDSHAKE_PLAIN_SIZE];
-    ck_assert_msg(recv(sock, (char *)response, TCP_SERVER_HANDSHAKE_SIZE, 0) == TCP_SERVER_HANDSHAKE_SIZE, "recv Failed.");
+    ck_assert_msg(net_recv(sock, response, TCP_SERVER_HANDSHAKE_SIZE) == TCP_SERVER_HANDSHAKE_SIZE, "recv Failed.");
     ret = decrypt_data(tcp_server_public_key(tcp_s), f_secret_key, response, response + CRYPTO_NONCE_SIZE,
                        TCP_SERVER_HANDSHAKE_SIZE - CRYPTO_NONCE_SIZE, response_plain);
     ck_assert_msg(ret == TCP_HANDSHAKE_PLAIN_SIZE, "Decrypt Failed.");
@@ -219,13 +221,13 @@ static int write_packet_TCP_secure_connection(struct sec_TCP_con *con, uint8_t *
 
     increment_nonce(con->sent_nonce);
 
-    ck_assert_msg(send(con->sock, (const char *)packet, SIZEOF_VLA(packet), 0) == SIZEOF_VLA(packet), "send failed");
+    ck_assert_msg(net_send(con->sock, packet, SIZEOF_VLA(packet)) == SIZEOF_VLA(packet), "send failed");
     return 0;
 }
 
 static int read_packet_sec_TCP(struct sec_TCP_con *con, uint8_t *data, uint16_t length)
 {
-    int len = recv(con->sock, (char *)data, length, 0);
+    int len = net_recv(con->sock, data, length);
     ck_assert_msg(len == length, "wrong len %i\n", len);
     len = decrypt_data_symmetric(con->shared_key, con->recv_nonce, data + 2, length - 2, data);
     ck_assert_msg(len != -1, "Decrypt failed");
diff --git a/auto_tests/monolith_test.cpp b/auto_tests/monolith_test.cpp
index 50c59995..853c88ec 100644
--- a/auto_tests/monolith_test.cpp
+++ b/auto_tests/monolith_test.cpp
@@ -286,7 +286,11 @@ int main(int argc, char *argv[])
     // toxcore/TCP_server
     CHECK_SIZE(TCP_Priority_List, 16);
     CHECK_SIZE(TCP_Secure_Connection, 11816);
+#ifdef TCP_SERVER_USE_EPOLL
+    CHECK_SIZE(TCP_Server, 6049968);  // 6MB!
+#else
     CHECK_SIZE(TCP_Server, 6049952);  // 6MB!
+#endif
     // toxcore/tox
     CHECK_SIZE(Tox_Options, 64);
 #endif
diff --git a/other/bootstrap_node_packets.c b/other/bootstrap_node_packets.c
index 614cb720..5b447c62 100644
--- a/other/bootstrap_node_packets.c
+++ b/other/bootstrap_node_packets.c
@@ -25,6 +25,8 @@
  */
 #include "bootstrap_node_packets.h"
 
+#include <string.h>
+
 #define INFO_REQUEST_PACKET_LENGTH 78
 
 static uint32_t bootstrap_version;
diff --git a/toxav/audio.c b/toxav/audio.c
index 58a93add..85639f16 100644
--- a/toxav/audio.c
+++ b/toxav/audio.c
@@ -23,12 +23,13 @@
 
 #include "audio.h"
 
+#include <stdlib.h>
+#include <string.h>
+
 #include "rtp.h"
 
 #include "../toxcore/logger.h"
 
-#include <stdlib.h>
-
 static struct JitterBuffer *jbuf_new(uint32_t capacity);
 static void jbuf_clear(struct JitterBuffer *q);
 static void jbuf_free(struct JitterBuffer *q);
diff --git a/toxav/bwcontroller.c b/toxav/bwcontroller.c
index d786080e..2d7dd659 100644
--- a/toxav/bwcontroller.c
+++ b/toxav/bwcontroller.c
@@ -23,14 +23,16 @@
 
 #include "bwcontroller.h"
 
+#include <assert.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+
 #include "ring_buffer.h"
 
 #include "../toxcore/logger.h"
 #include "../toxcore/util.h"
 
-#include <assert.h>
-#include <errno.h>
-
 #define BWC_PACKET_ID 196
 #define BWC_SEND_INTERVAL_MS 950     /* 0.95s  */
 #define BWC_AVG_PKT_COUNT 20
diff --git a/toxav/groupav.c b/toxav/groupav.c
index e9595b4e..f0cb3a5b 100644
--- a/toxav/groupav.c
+++ b/toxav/groupav.c
@@ -23,6 +23,9 @@
 
 #include "groupav.h"
 
+#include <stdlib.h>
+#include <string.h>
+
 #include "../toxcore/logger.h"
 #include "../toxcore/util.h"
 
diff --git a/toxav/rtp.c b/toxav/rtp.c
index a65dbafe..d40ad9d3 100644
--- a/toxav/rtp.c
+++ b/toxav/rtp.c
@@ -23,16 +23,17 @@
 
 #include "rtp.h"
 
+#include <assert.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+
 #include "bwcontroller.h"
 
 #include "../toxcore/Messenger.h"
 #include "../toxcore/logger.h"
 #include "../toxcore/util.h"
 
-#include <assert.h>
-#include <errno.h>
-#include <stdlib.h>
-
 enum {
     /**
      * The number of milliseconds we want to keep a keyframe in the buffer for,
diff --git a/toxav/video.c b/toxav/video.c
index 1d01d08a..8c31cf75 100644
--- a/toxav/video.c
+++ b/toxav/video.c
@@ -23,6 +23,10 @@
 
 #include "video.h"
 
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+
 #include "msi.h"
 #include "ring_buffer.h"
 #include "rtp.h"
@@ -30,9 +34,6 @@
 #include "../toxcore/logger.h"
 #include "../toxcore/network.h"
 
-#include <assert.h>
-#include <stdlib.h>
-
 /**
  * Soft deadline the decoder should attempt to meet, in "us" (microseconds).
  * Set to zero for unlimited.
diff --git a/toxcore/BUILD.bazel b/toxcore/BUILD.bazel
index 3dfa1648..1889a702 100644
--- a/toxcore/BUILD.bazel
+++ b/toxcore/BUILD.bazel
@@ -123,6 +123,11 @@ cc_library(
         "TCP_connection.c",
         "TCP_server.c",
     ],
+    copts = select({
+        "//tools/config:freebsd": [],
+        "//tools/config:linux": ["-DTCP_SERVER_USE_EPOLL=1"],
+        "//tools/config:osx": [],
+    }),
     hdrs = [
         "TCP_client.h",
         "TCP_connection.h",
diff --git a/toxcore/DHT.c b/toxcore/DHT.c
index f611fca6..31d2ca0a 100644
--- a/toxcore/DHT.c
+++ b/toxcore/DHT.c
@@ -3,7 +3,7 @@
  */
 
 /*
- * Copyright © 2016-2017 The TokTok team.
+ * Copyright © 2016-2018 The TokTok team.
  * Copyright © 2013 Tox project.
  *
  * This file is part of Tox, the free peer to peer instant messenger.
@@ -34,6 +34,8 @@
 #include "util.h"
 
 #include <assert.h>
+#include <stdlib.h>
+#include <string.h>
 
 /* The timeout after which a node is discarded completely. */
 #define KILL_NODE_TIMEOUT (BAD_NODE_TIMEOUT + PING_INTERVAL)
diff --git a/toxcore/LAN_discovery.c b/toxcore/LAN_discovery.c
index 70b71fea..0bb96926 100644
--- a/toxcore/LAN_discovery.c
+++ b/toxcore/LAN_discovery.c
@@ -27,6 +27,8 @@
 
 #include "LAN_discovery.h"
 
+#include <string.h>
+
 #include "util.h"
 
 #define MAX_INTERFACES 16
@@ -37,7 +39,15 @@
 static int     broadcast_count = -1;
 static IP_Port broadcast_ip_ports[MAX_INTERFACES];
 
-#if defined(_WIN32) || defined(__WIN32__) || defined (WIN32)
+#if defined(_WIN32) || defined(__WIN32__) || defined(WIN32)
+
+// The mingw32/64 Windows library warns about including winsock2.h after
+// windows.h even though with the above it's a valid thing to do. So, to make
+// mingw32 headers happy, we include winsock2.h first.
+#include <winsock2.h>
+
+#include <windows.h>
+#include <ws2tcpip.h>
 
 #include <iphlpapi.h>
 
@@ -108,6 +118,12 @@ static void fetch_broadcast_info(uint16_t port)
 
 #elif defined(__linux__) || defined(__FreeBSD__)
 
+#include <netinet/in.h>
+#include <sys/ioctl.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <unistd.h>
+
 #ifdef __linux__
 #include <linux/netdevice.h>
 #endif
@@ -116,8 +132,6 @@ static void fetch_broadcast_info(uint16_t port)
 #include <net/if.h>
 #endif
 
-#include <sys/ioctl.h>
-
 static void fetch_broadcast_info(uint16_t port)
 {
     /* Not sure how many platforms this will run on,
@@ -127,7 +141,7 @@ static void fetch_broadcast_info(uint16_t port)
     broadcast_count = 0;
     const Socket sock = net_socket(TOX_AF_INET, TOX_SOCK_STREAM, 0);
 
-    if (sock < 0) {
+    if (!sock_valid(sock)) {
         return;
     }
 
@@ -139,8 +153,8 @@ static void fetch_broadcast_info(uint16_t port)
     ifconf.ifc_buf = (char *)i_faces;
     ifconf.ifc_len = sizeof(i_faces);
 
-    if (ioctl(sock, SIOCGIFCONF, &ifconf) < 0) {
-        close(sock);
+    if (ioctl(sock.socket, SIOCGIFCONF, &ifconf) < 0) {
+        kill_sock(sock);
         return;
     }
 
@@ -160,12 +174,12 @@ static void fetch_broadcast_info(uint16_t port)
 
     for (int i = 0; i < n; i++) {
         /* there are interfaces with are incapable of broadcast */
-        if (ioctl(sock, SIOCGIFBRDADDR, &i_faces[i]) < 0) {
+        if (ioctl(sock.socket, SIOCGIFBRDADDR, &i_faces[i]) < 0) {
             continue;
         }
 
-        /* moot check: only TOX_AF_INET returned (backwards compat.) */
-        if (i_faces[i].ifr_broadaddr.sa_family != TOX_AF_INET) {
+        /* moot check: only AF_INET returned (backwards compat.) */
+        if (i_faces[i].ifr_broadaddr.sa_family != AF_INET) {
             continue;
         }
 
@@ -187,7 +201,7 @@ static void fetch_broadcast_info(uint16_t port)
         count++;
     }
 
-    close(sock);
+    kill_sock(sock);
 
     broadcast_count = count;
 
diff --git a/toxcore/Messenger.c b/toxcore/Messenger.c
index 2408c844..c381db0c 100644
--- a/toxcore/Messenger.c
+++ b/toxcore/Messenger.c
@@ -27,12 +27,16 @@
 
 #include "Messenger.h"
 
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+
 #include "logger.h"
 #include "network.h"
 #include "util.h"
 
-#include <assert.h>
-
 static int write_cryptpacket_id(const Messenger *m, int32_t friendnumber, uint8_t packet_id, const uint8_t *data,
                                 uint32_t length, uint8_t congestion_control);
 
diff --git a/toxcore/TCP_client.c b/toxcore/TCP_client.c
index a6c32f9c..58e8de49 100644
--- a/toxcore/TCP_client.c
+++ b/toxcore/TCP_client.c
@@ -27,11 +27,11 @@
 
 #include "TCP_client.h"
 
-#include "util.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
 
-#if !defined(_WIN32) && !defined(__WIN32__) && !defined (WIN32)
-#include <sys/ioctl.h>
-#endif
+#include "util.h"
 
 struct TCP_Client_Connection {
     TCP_CLIENT_STATUS status;
@@ -177,7 +177,7 @@ static int proxy_http_read_connection_response(TCP_Client_Connection *TCP_conn)
 
     if (strstr((char *)data, success)) {
         // drain all data
-        unsigned int data_left = TCP_socket_data_recv_buffer(TCP_conn->sock);
+        unsigned int data_left = net_socket_data_recv_buffer(TCP_conn->sock);
 
         if (data_left) {
             VLA(uint8_t, temp_data, data_left);
@@ -332,9 +332,8 @@ static int client_send_pending_data_nonpriority(TCP_Client_Connection *con)
         return 0;
     }
 
-    uint16_t left = con->last_packet_length - con->last_packet_sent;
-    const char *data = (const char *)(con->last_packet + con->last_packet_sent);
-    int len = send(con->sock, data, left, MSG_NOSIGNAL);
+    const uint16_t left = con->last_packet_length - con->last_packet_sent;
+    const int len = net_send(con->sock, con->last_packet + con->last_packet_sent, left);
 
     if (len <= 0) {
         return -1;
@@ -363,8 +362,8 @@ static int client_send_pending_data(TCP_Client_Connection *con)
     TCP_Priority_List *p = con->priority_queue_start;
 
     while (p) {
-        uint16_t left = p->size - p->sent;
-        int len = send(con->sock, (const char *)(p->data + p->sent), left, MSG_NOSIGNAL);
+        const uint16_t left = p->size - p->sent;
+        const int len = net_send(con->sock, p->data + p->sent, left);
 
         if (len != left) {
             if (len > 0) {
@@ -459,7 +458,7 @@ static int write_packet_TCP_client_secure_connection(TCP_Client_Connection *con,
     }
 
     if (priority) {
-        len = sendpriority ? send(con->sock, (const char *)packet, SIZEOF_VLA(packet), MSG_NOSIGNAL) : 0;
+        len = sendpriority ? net_send(con->sock, packet, SIZEOF_VLA(packet)) : 0;
 
         if (len <= 0) {
             len = 0;
@@ -474,7 +473,7 @@ static int write_packet_TCP_client_secure_connection(TCP_Client_Connection *con,
         return client_add_priority(con, packet, SIZEOF_VLA(packet), len);
     }
 
-    len = send(con->sock, (const char *)packet, SIZEOF_VLA(packet), MSG_NOSIGNAL);
+    len = net_send(con->sock, packet, SIZEOF_VLA(packet));
 
     if (len <= 0) {
         return 0;
diff --git a/toxcore/TCP_connection.c b/toxcore/TCP_connection.c
index d10114f6..72642264 100644
--- a/toxcore/TCP_connection.c
+++ b/toxcore/TCP_connection.c
@@ -27,9 +27,11 @@
 
 #include "TCP_connection.h"
 
-#include "util.h"
-
 #include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "util.h"
 
 
 struct TCP_Connections {
diff --git a/toxcore/TCP_server.c b/toxcore/TCP_server.c
index 4541fce0..28a441ad 100644
--- a/toxcore/TCP_server.c
+++ b/toxcore/TCP_server.c
@@ -27,12 +27,20 @@
 
 #include "TCP_server.h"
 
-#include "util.h"
-
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
 #if !defined(_WIN32) && !defined(__WIN32__) && !defined (WIN32)
 #include <sys/ioctl.h>
 #endif
 
+#ifdef TCP_SERVER_USE_EPOLL
+#include <sys/epoll.h>
+#include <unistd.h>
+#endif
+
+#include "util.h"
+
 typedef struct TCP_Secure_Connection {
     Socket sock;
     uint8_t public_key[CRYPTO_PUBLIC_KEY_SIZE];
@@ -231,22 +239,6 @@ static int del_accepted(TCP_Server *TCP_server, int index)
     return 0;
 }
 
-/* return the amount of data in the tcp recv buffer.
- * return 0 on failure.
- */
-unsigned int TCP_socket_data_recv_buffer(Socket sock)
-{
-#if defined(_WIN32) || defined(__WIN32__) || defined (WIN32)
-    unsigned long count = 0;
-    ioctlsocket(sock, FIONREAD, &count);
-#else
-    int count = 0;
-    ioctl(sock, FIONREAD, &count);
-#endif
-
-    return count;
-}
-
 /* Read the next two bytes in TCP stream then convert them to
  * length (host byte order).
  *
@@ -256,11 +248,11 @@ unsigned int TCP_socket_data_recv_buffer(Socket sock)
  */
 uint16_t read_TCP_length(Socket sock)
 {
-    unsigned int count = TCP_socket_data_recv_buffer(sock);
+    const unsigned int count = net_socket_data_recv_buffer(sock);
 
     if (count >= sizeof(uint16_t)) {
         uint16_t length;
-        int len = recv(sock, (char *)&length, sizeof(uint16_t), MSG_NOSIGNAL);
+        const int len = net_recv(sock, &length, sizeof(uint16_t));
 
         if (len != sizeof(uint16_t)) {
             fprintf(stderr, "FAIL recv packet\n");
@@ -286,10 +278,10 @@ uint16_t read_TCP_length(Socket sock)
  */
 int read_TCP_packet(Socket sock, uint8_t *data, uint16_t length)
 {
-    unsigned int count = TCP_socket_data_recv_buffer(sock);
+    unsigned int count = net_socket_data_recv_buffer(sock);
 
     if (count >= length) {
-        int len = recv(sock, (char *)data, length, MSG_NOSIGNAL);
+        const int len = net_recv(sock, data, length);
 
         if (len != length) {
             fprintf(stderr, "FAIL recv packet\n");
@@ -356,8 +348,8 @@ static int send_pending_data_nonpriority(TCP_Secure_Connection *con)
         return 0;
     }
 
-    uint16_t left = con->last_packet_length - con->last_packet_sent;
-    int len = send(con->sock, (const char *)(con->last_packet + con->last_packet_sent), left, MSG_NOSIGNAL);
+    const uint16_t left = con->last_packet_length - con->last_packet_sent;
+    const int len = net_send(con->sock, con->last_packet + con->last_packet_sent, left);
 
     if (len <= 0) {
         return -1;
@@ -386,8 +378,8 @@ static int send_pending_data(TCP_Secure_Connection *con)
     TCP_Priority_List *p = con->priority_queue_start;
 
     while (p) {
-        uint16_t left = p->size - p->sent;
-        int len = send(con->sock, (const char *)(p->data + p->sent), left, MSG_NOSIGNAL);
+        const uint16_t left = p->size - p->sent;
+        const int len = net_send(con->sock, p->data + p->sent, left);
 
         if (len != left) {
             if (len > 0) {
@@ -462,7 +454,7 @@ static int write_packet_TCP_secure_connection(TCP_Secure_Connection *con, const
 
     VLA(uint8_t, packet, sizeof(uint16_t) + length + CRYPTO_MAC_SIZE);
 
-    uint16_t c_length = net_htons(length + CRYPTO_MAC_SIZE);
+    const uint16_t c_length = net_htons(length + CRYPTO_MAC_SIZE);
     memcpy(packet, &c_length, sizeof(uint16_t));
     int len = encrypt_data_symmetric(con->shared_key, con->sent_nonce, data, length, packet + sizeof(uint16_t));
 
@@ -471,7 +463,7 @@ static int write_packet_TCP_secure_connection(TCP_Secure_Connection *con, const
     }
 
     if (priority) {
-        len = sendpriority ? send(con->sock, (const char *)packet, SIZEOF_VLA(packet), MSG_NOSIGNAL) : 0;
+        len = sendpriority ? net_send(con->sock, packet, SIZEOF_VLA(packet)) : 0;
 
         if (len <= 0) {
             len = 0;
@@ -486,7 +478,7 @@ static int write_packet_TCP_secure_connection(TCP_Secure_Connection *con, const
         return add_priority(con, packet, SIZEOF_VLA(packet), len);
     }
 
-    len = send(con->sock, (const char *)packet, SIZEOF_VLA(packet), MSG_NOSIGNAL);
+    len = net_send(con->sock, packet, SIZEOF_VLA(packet));
 
     if (len <= 0) {
         return 0;
@@ -583,7 +575,7 @@ static int handle_TCP_handshake(TCP_Secure_Connection *con, const uint8_t *data,
         return -1;
     }
 
-    if (TCP_SERVER_HANDSHAKE_SIZE != send(con->sock, (const char *)response, TCP_SERVER_HANDSHAKE_SIZE, MSG_NOSIGNAL)) {
+    if (TCP_SERVER_HANDSHAKE_SIZE != net_send(con->sock, response, TCP_SERVER_HANDSHAKE_SIZE)) {
         return -1;
     }
 
@@ -1005,12 +997,12 @@ static int accept_connection(TCP_Server *TCP_server, Socket sock)
     return index;
 }
 
-static Socket new_listening_TCP_socket(int family, uint16_t port)
+static Socket new_listening_TCP_socket(Family family, uint16_t port)
 {
     Socket sock = net_socket(family, TOX_SOCK_STREAM, TOX_PROTO_TCP);
 
     if (!sock_valid(sock)) {
-        return ~0;
+        return net_invalid_socket;
     }
 
     int ok = set_socket_nonblock(sock);
@@ -1023,11 +1015,11 @@ static Socket new_listening_TCP_socket(int family, uint16_t port)
         ok = set_socket_reuseaddr(sock);
     }
 
-    ok = ok && bind_to_port(sock, family, port) && (listen(sock, TCP_MAX_BACKLOG) == 0);
+    ok = ok && bind_to_port(sock, family, port) && (net_listen(sock, TCP_MAX_BACKLOG) == 0);
 
     if (!ok) {
         kill_sock(sock);
-        return ~0;
+        return net_invalid_socket;
     }
 
     return sock;
@@ -1087,9 +1079,9 @@ TCP_Server *new_TCP_server(uint8_t ipv6_enabled, uint16_t num_sockets, const uin
         if (sock_valid(sock)) {
 #ifdef TCP_SERVER_USE_EPOLL
             ev.events = EPOLLIN | EPOLLET;
-            ev.data.u64 = sock | ((uint64_t)TCP_SOCKET_LISTENING << 32);
+            ev.data.u64 = sock.socket | ((uint64_t)TCP_SOCKET_LISTENING << 32);
 
-            if (epoll_ctl(temp->efd, EPOLL_CTL_ADD, sock, &ev) == -1) {
+            if (epoll_ctl(temp->efd, EPOLL_CTL_ADD, sock.socket, &ev) == -1) {
                 continue;
             }
 
@@ -1119,20 +1111,20 @@ TCP_Server *new_TCP_server(uint8_t ipv6_enabled, uint16_t num_sockets, const uin
     return temp;
 }
 
+#ifndef TCP_SERVER_USE_EPOLL
 static void do_TCP_accept_new(TCP_Server *TCP_server)
 {
     uint32_t i;
 
     for (i = 0; i < TCP_server->num_listening_socks; ++i) {
-        struct sockaddr_storage addr;
-        socklen_t addrlen = sizeof(addr);
         Socket sock;
 
         do {
-            sock = accept(TCP_server->socks_listening[i], (struct sockaddr *)&addr, &addrlen);
+            sock = net_accept(TCP_server->socks_listening[i]);
         } while (accept_connection(TCP_server, sock) != -1);
     }
 }
+#endif
 
 static int do_incoming(TCP_Server *TCP_server, uint32_t i)
 {
@@ -1208,6 +1200,7 @@ static void do_confirmed_recv(TCP_Server *TCP_server, uint32_t i)
     }
 }
 
+#ifndef TCP_SERVER_USE_EPOLL
 static void do_TCP_incoming(TCP_Server *TCP_server)
 {
     uint32_t i;
@@ -1225,6 +1218,7 @@ static void do_TCP_unconfirmed(TCP_Server *TCP_server)
         do_unconfirmed(TCP_server, i);
     }
 }
+#endif
 
 static void do_TCP_confirmed(TCP_Server *TCP_server)
 {
@@ -1294,8 +1288,9 @@ static void do_TCP_epoll(TCP_Server *TCP_server)
         int n;
 
         for (n = 0; n < nfds; ++n) {
-            Socket sock = events[n].data.u64 & 0xFFFFFFFF;
-            int status = (events[n].data.u64 >> 32) & 0xFF, index = (events[n].data.u64 >> 40);
+            const Socket sock = {(int)(events[n].data.u64 & 0xFFFFFFFF)};
+            const int status = (events[n].data.u64 >> 32) & 0xFF;
+            const int index = events[n].data.u64 >> 40;
 
             if ((events[n].events & EPOLLERR) || (events[n].events & EPOLLHUP) || (events[n].events & EPOLLRDHUP)) {
                 switch (status) {
@@ -1331,11 +1326,8 @@ static void do_TCP_epoll(TCP_Server *TCP_server)
             switch (status) {
                 case TCP_SOCKET_LISTENING: {
                     //socket is from socks_listening, accept connection
-                    struct sockaddr_storage addr;
-                    socklen_t addrlen = sizeof(addr);
-
                     while (1) {
-                        Socket sock_new = accept(sock, (struct sockaddr *)&addr, &addrlen);
+                        Socket sock_new = net_accept(sock);
 
                         if (!sock_valid(sock_new)) {
                             break;
@@ -1349,10 +1341,10 @@ static void do_TCP_epoll(TCP_Server *TCP_server)
 
                         struct epoll_event ev = {
                             .events = EPOLLIN | EPOLLET | EPOLLRDHUP,
-                            .data.u64 = sock_new | ((uint64_t)TCP_SOCKET_INCOMING << 32) | ((uint64_t)index_new << 40)
+                            .data.u64 = sock_new.socket | ((uint64_t)TCP_SOCKET_INCOMING << 32) | ((uint64_t)index_new << 40)
                         };
 
-                        if (epoll_ctl(TCP_server->efd, EPOLL_CTL_ADD, sock_new, &ev) == -1) {
+                        if (epoll_ctl(TCP_server->efd, EPOLL_CTL_ADD, sock_new.socket, &ev) == -1) {
                             kill_TCP_secure_connection(&TCP_server->incoming_connection_queue[index_new]);
                             continue;
                         }
@@ -1366,9 +1358,9 @@ static void do_TCP_epoll(TCP_Server *TCP_server)
 
                     if ((index_new = do_incoming(TCP_server, index)) != -1) {
                         events[n].events = EPOLLIN | EPOLLET | EPOLLRDHUP;
-                        events[n].data.u64 = sock | ((uint64_t)TCP_SOCKET_UNCONFIRMED << 32) | ((uint64_t)index_new << 40);
+                        events[n].data.u64 = sock.socket | ((uint64_t)TCP_SOCKET_UNCONFIRMED << 32) | ((uint64_t)index_new << 40);
 
-                        if (epoll_ctl(TCP_server->efd, EPOLL_CTL_MOD, sock, &events[n]) == -1) {
+                        if (epoll_ctl(TCP_server->efd, EPOLL_CTL_MOD, sock.socket, &events[n]) == -1) {
                             kill_TCP_secure_connection(&TCP_server->unconfirmed_connection_queue[index_new]);
                             break;
                         }
@@ -1382,9 +1374,9 @@ static void do_TCP_epoll(TCP_Server *TCP_server)
 
                     if ((index_new = do_unconfirmed(TCP_server, index)) != -1) {
                         events[n].events = EPOLLIN | EPOLLET | EPOLLRDHUP;
-                        events[n].data.u64 = sock | ((uint64_t)TCP_SOCKET_CONFIRMED << 32) | ((uint64_t)index_new << 40);
+                        events[n].data.u64 = sock.socket | ((uint64_t)TCP_SOCKET_CONFIRMED << 32) | ((uint64_t)index_new << 40);
 
-                        if (epoll_ctl(TCP_server->efd, EPOLL_CTL_MOD, sock, &events[n]) == -1) {
+                        if (epoll_ctl(TCP_server->efd, EPOLL_CTL_MOD, sock.socket, &events[n]) == -1) {
                             //remove from confirmed connections
                             kill_accepted(TCP_server, index_new);
                             break;
diff --git a/toxcore/TCP_server.h b/toxcore/TCP_server.h
index 234f5ad1..c8cbeda0 100644
--- a/toxcore/TCP_server.h
+++ b/toxcore/TCP_server.h
@@ -32,11 +32,6 @@
 #include <sys/epoll.h>
 #endif
 
-// Disable MSG_NOSIGNAL on systems not supporting it, e.g. Windows, FreeBSD
-#if !defined(MSG_NOSIGNAL)
-#define MSG_NOSIGNAL 0
-#endif
-
 #define MAX_INCOMING_CONNECTIONS 256
 
 #define TCP_MAX_BACKLOG MAX_INCOMING_CONNECTIONS
@@ -108,11 +103,6 @@ void do_TCP_server(TCP_Server *TCP_server);
  */
 void kill_TCP_server(TCP_Server *TCP_server);
 
-/* return the amount of data in the tcp recv buffer.
- * return 0 on failure.
- */
-unsigned int TCP_socket_data_recv_buffer(Socket sock);
-
 /* Read the next two bytes in TCP stream then convert them to
  * length (host byte order).
  *
diff --git a/toxcore/crypto_core.api.h b/toxcore/crypto_core.api.h
index e9e8aeb2..4b40860d 100644
--- a/toxcore/crypto_core.api.h
+++ b/toxcore/crypto_core.api.h
@@ -26,8 +26,8 @@
 #define CRYPTO_CORE_H
 
 #include <stdbool.h>
+#include <stddef.h>
 #include <stdint.h>
-#include <stdlib.h>
 
 #ifdef __cplusplus
 extern "C" {
diff --git a/toxcore/crypto_core.h b/toxcore/crypto_core.h
index e7e913b6..18c1339e 100644
--- a/toxcore/crypto_core.h
+++ b/toxcore/crypto_core.h
@@ -25,8 +25,8 @@
 #define CRYPTO_CORE_H
 
 #include <stdbool.h>
+#include <stddef.h>
 #include <stdint.h>
-#include <stdlib.h>
 
 #ifdef __cplusplus
 extern "C" {
diff --git a/toxcore/friend_connection.c b/toxcore/friend_connection.c
index 6f5685fb..0ba8178f 100644
--- a/toxcore/friend_connection.c
+++ b/toxcore/friend_connection.c
@@ -27,6 +27,10 @@
 
 #include "friend_connection.h"
 
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
 #include "util.h"
 
 #define PORTS_PER_DISCOVERY 10
diff --git a/toxcore/friend_requests.c b/toxcore/friend_requests.c
index 13c89eae..3123e4ff 100644
--- a/toxcore/friend_requests.c
+++ b/toxcore/friend_requests.c
@@ -27,6 +27,9 @@
 
 #include "friend_requests.h"
 
+#include <stdlib.h>
+#include <string.h>
+
 #include "util.h"
 
 struct Friend_Requests {
diff --git a/toxcore/group.c b/toxcore/group.c
index 37b4437d..b77ae38a 100644
--- a/toxcore/group.c
+++ b/toxcore/group.c
@@ -27,6 +27,9 @@
 
 #include "group.h"
 
+#include <stdlib.h>
+#include <string.h>
+
 #include "util.h"
 
 /* return 1 if the groupnumber is not valid.
diff --git a/toxcore/list.c b/toxcore/list.c
index 8fd1f5fb..7b65e184 100644
--- a/toxcore/list.c
+++ b/toxcore/list.c
@@ -29,6 +29,9 @@
 
 #include "list.h"
 
+#include <stdlib.h>
+#include <string.h>
+
 #include "ccompat.h"
 
 /* Basically, the elements in the list are placed in order so that they can be searched for easily
diff --git a/toxcore/list.h b/toxcore/list.h
index cb3b328c..9ad8f44d 100644
--- a/toxcore/list.h
+++ b/toxcore/list.h
@@ -27,8 +27,6 @@
 #define LIST_H
 
 #include <stdint.h>
-#include <stdlib.h>
-#include <string.h>
 
 typedef struct {
     uint32_t n; //number of elements
diff --git a/toxcore/net_crypto.c b/toxcore/net_crypto.c
index 2e8299f1..b9d8a360 100644
--- a/toxcore/net_crypto.c
+++ b/toxcore/net_crypto.c
@@ -29,9 +29,11 @@
 
 #include "net_crypto.h"
 
-#include "util.h"
-
 #include <math.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "util.h"
 
 typedef struct {
     uint64_t sent_time;
diff --git a/toxcore/network.c b/toxcore/network.c
index 984071d4..f357d887 100644
--- a/toxcore/network.c
+++ b/toxcore/network.c
@@ -38,44 +38,65 @@
 #define _WIN32_WINNT  0x501
 #endif
 
+#if !defined(OS_WIN32) && (defined(_WIN32) || defined(__WIN32__) || defined(WIN32))
+#define OS_WIN32
+#endif
+
+#ifdef OS_WIN32
+#ifndef WINVER
+//Windows XP
+#define WINVER 0x0501
+#endif
+#endif
+
+#ifdef PLAN9
+#include <u.h> // Plan 9 requires this is imported first
+// Comment line here to avoid reordering by source code formatters.
+#include <libc.h>
+#endif
+
+#ifdef OS_WIN32 /* Put win32 includes here */
+// The mingw32/64 Windows library warns about including winsock2.h after
+// windows.h even though with the above it's a valid thing to do. So, to make
+// mingw32 headers happy, we include winsock2.h first.
+#include <winsock2.h>
+// Comment line here to avoid reordering by source code formatters.
+#include <windows.h>
+#include <ws2tcpip.h>
+#endif
+
 #include "network.h"
 
-#include "logger.h"
-#include "util.h"
-
-#include <assert.h>
 #ifdef __APPLE__
 #include <mach/clock.h>
 #include <mach/mach.h>
 #endif
 
-#ifndef IPV6_ADD_MEMBERSHIP
-#ifdef  IPV6_JOIN_GROUP
-#define IPV6_ADD_MEMBERSHIP IPV6_JOIN_GROUP
-#endif
-#endif
-
-#if !(defined(_WIN32) || defined(__WIN32__) || defined(WIN32))
+#if !defined(OS_WIN32)
 
+#include <arpa/inet.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <netdb.h>
+#include <netinet/in.h>
+#include <sys/ioctl.h>
+#include <sys/socket.h>
 #include <sys/time.h>
 #include <sys/types.h>
+#include <unistd.h>
 
 #define TOX_EWOULDBLOCK EWOULDBLOCK
 
 #else
-
 #ifndef IPV6_V6ONLY
 #define IPV6_V6ONLY 27
 #endif
 
 #define TOX_EWOULDBLOCK WSAEWOULDBLOCK
 
-static const char *inet_ntop(Family family, const void *addr, char *buf, size_t bufsize)
+static const char *inet_ntop(int family, const void *addr, char *buf, size_t bufsize)
 {
-    if (family == TOX_AF_INET) {
+    if (family == AF_INET) {
         struct sockaddr_in saddr;
         memset(&saddr, 0, sizeof(saddr));
 
@@ -89,7 +110,7 @@ static const char *inet_ntop(Family family, const void *addr, char *buf, size_t
         }
 
         return buf;
-    } else if (family == TOX_AF_INET6) {
+    } else if (family == AF_INET6) {
         struct sockaddr_in6 saddr;
         memset(&saddr, 0, sizeof(saddr));
 
@@ -108,9 +129,9 @@ static const char *inet_ntop(Family family, const void *addr, char *buf, size_t
     return nullptr;
 }
 
-static int inet_pton(Family family, const char *addrString, void *addrbuf)
+static int inet_pton(int family, const char *addrString, void *addrbuf)
 {
-    if (family == TOX_AF_INET) {
+    if (family == AF_INET) {
         struct sockaddr_in saddr;
         memset(&saddr, 0, sizeof(saddr));
 
@@ -123,7 +144,7 @@ static int inet_pton(Family family, const char *addrString, void *addrbuf)
         *(struct in_addr *)addrbuf = saddr.sin_addr;
 
         return 1;
-    } else if (family == TOX_AF_INET6) {
+    } else if (family == AF_INET6) {
         struct sockaddr_in6 saddr;
         memset(&saddr, 0, sizeof(saddr));
 
@@ -143,6 +164,25 @@ static int inet_pton(Family family, const char *addrString, void *addrbuf)
 
 #endif
 
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "logger.h"
+#include "util.h"
+
+// Disable MSG_NOSIGNAL on systems not supporting it, e.g. Windows, FreeBSD
+#if !defined(MSG_NOSIGNAL)
+#define MSG_NOSIGNAL 0
+#endif
+
+#ifndef IPV6_ADD_MEMBERSHIP
+#ifdef IPV6_JOIN_GROUP
+#define IPV6_ADD_MEMBERSHIP IPV6_JOIN_GROUP
+#endif
+#endif
+
 #if TOX_INET6_ADDRSTRLEN < INET6_ADDRSTRLEN
 #error TOX_INET6_ADDRSTRLEN should be greater or equal to INET6_ADDRSTRLEN (#INET6_ADDRSTRLEN)
 #endif
@@ -153,8 +193,40 @@ static int inet_pton(Family family, const char *addrString, void *addrbuf)
 
 static int make_proto(int proto);
 static int make_socktype(int type);
-static int make_family(int tox_family);
-static int make_tox_family(int family);
+
+static int make_family(Family tox_family)
+{
+    switch (tox_family) {
+        case TOX_AF_INET:
+            return AF_INET;
+
+        case TOX_AF_INET6:
+            return AF_INET6;
+
+        case TOX_AF_UNSPEC:
+            return AF_UNSPEC;
+
+        default:
+            return tox_family;
+    }
+}
+
+static Family make_tox_family(int family)
+{
+    switch (family) {
+        case AF_INET:
+            return TOX_AF_INET;
+
+        case AF_INET6:
+            return TOX_AF_INET6;
+
+        case AF_UNSPEC:
+            return TOX_AF_UNSPEC;
+
+        default:
+            return family;
+    }
+}
 
 static void get_ip4(IP4 *result, const struct in_addr *addr)
 {
@@ -201,6 +273,14 @@ IP6 get_ip6_loopback(void)
     return loopback;
 }
 
+const Socket net_invalid_socket = {
+#ifdef OS_WIN32
+    (int)INVALID_SOCKET,
+#else
+    -1,
+#endif
+};
+
 /* Check if socket is valid.
  *
  * return 1 if valid
@@ -208,27 +288,17 @@ IP6 get_ip6_loopback(void)
  */
 int sock_valid(Socket sock)
 {
-#if defined(_WIN32) || defined(__WIN32__) || defined (WIN32)
-
-    if (sock == INVALID_SOCKET) {
-#else
-
-    if (sock < 0) {
-#endif
-        return 0;
-    }
-
-    return 1;
+    return sock.socket != net_invalid_socket.socket;
 }
 
 /* Close the socket.
  */
 void kill_sock(Socket sock)
 {
-#if defined(_WIN32) || defined(__WIN32__) || defined (WIN32)
-    closesocket(sock);
+#ifdef OS_WIN32
+    closesocket(sock.socket);
 #else
-    close(sock);
+    close(sock.socket);
 #endif
 }
 
@@ -239,11 +309,11 @@ void kill_sock(Socket sock)
  */
 int set_socket_nonblock(Socket sock)
 {
-#if defined(_WIN32) || defined(__WIN32__) || defined (WIN32)
+#ifdef OS_WIN32
     u_long mode = 1;
-    return (ioctlsocket(sock, FIONBIO, &mode) == 0);
+    return (ioctlsocket(sock.socket, FIONBIO, &mode) == 0);
 #else
-    return (fcntl(sock, F_SETFL, O_NONBLOCK, 1) == 0);
+    return (fcntl(sock.socket, F_SETFL, O_NONBLOCK, 1) == 0);
 #endif
 }
 
@@ -256,7 +326,7 @@ int set_socket_nosigpipe(Socket sock)
 {
 #if defined(__MACH__)
     int set = 1;
-    return (setsockopt(sock, SOL_SOCKET, SO_NOSIGPIPE, (const char *)&set, sizeof(int)) == 0);
+    return setsockopt(sock.socket, SOL_SOCKET, SO_NOSIGPIPE, (const char *)&set, sizeof(int)) == 0;
 #else
     return 1;
 #endif
@@ -270,7 +340,7 @@ int set_socket_nosigpipe(Socket sock)
 int set_socket_reuseaddr(Socket sock)
 {
     int set = 1;
-    return (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (const char *)&set, sizeof(set)) == 0);
+    return setsockopt(sock.socket, SOL_SOCKET, SO_REUSEADDR, (const char *)&set, sizeof(set)) == 0;
 }
 
 /* Set socket to dual (IPv4 + IPv6 socket)
@@ -282,14 +352,14 @@ int set_socket_dualstack(Socket sock)
 {
     int ipv6only = 0;
     socklen_t optsize = sizeof(ipv6only);
-    int res = getsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, (char *)&ipv6only, &optsize);
+    int res = getsockopt(sock.socket, IPPROTO_IPV6, IPV6_V6ONLY, (char *)&ipv6only, &optsize);
 
     if ((res == 0) && (ipv6only == 0)) {
         return 1;
     }
 
     ipv6only = 0;
-    return (setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, (const char *)&ipv6only, sizeof(ipv6only)) == 0);
+    return setsockopt(sock.socket, IPPROTO_IPV6, IPV6_V6ONLY, (const char *)&ipv6only, sizeof(ipv6only)) == 0;
 }
 
 
@@ -297,7 +367,7 @@ int set_socket_dualstack(Socket sock)
 static uint64_t current_time_actual(void)
 {
     uint64_t time;
-#if defined(_WIN32) || defined(__WIN32__) || defined (WIN32)
+#ifdef OS_WIN32
     /* This probably works fine */
     FILETIME ft;
     GetSystemTimeAsFileTime(&ft);
@@ -315,7 +385,7 @@ static uint64_t current_time_actual(void)
 }
 
 
-#if defined(_WIN32) || defined(__WIN32__) || defined (WIN32)
+#ifdef OS_WIN32
 static uint64_t last_monotime;
 static uint64_t add_monotime;
 #endif
@@ -324,7 +394,7 @@ static uint64_t add_monotime;
 uint64_t current_time_monotonic(void)
 {
     uint64_t time;
-#if defined(_WIN32) || defined(__WIN32__) || defined (WIN32)
+#ifdef OS_WIN32
     uint64_t old_add_monotime = add_monotime;
     time = (uint64_t)GetTickCount() + add_monotime;
 
@@ -472,11 +542,11 @@ int sendpacket(Networking_Core *net, IP_Port ip_port, const uint8_t *data, uint1
         addr6->sin6_flowinfo = 0;
         addr6->sin6_scope_id = 0;
     } else {
-        /* unknown address type*/
+        LOGGER_WARNING(net->log, "unknown address type: %d", ip_port.ip.family);
         return -1;
     }
 
-    const int res = sendto(net->sock, (const char *) data, length, 0, (struct sockaddr *)&addr, addrsize);
+    const int res = sendto(net->sock.socket, (const char *) data, length, 0, (struct sockaddr *)&addr, addrsize);
 
     loglogdata(net->log, "O=>", data, length, ip_port, res);
 
@@ -492,13 +562,13 @@ static int receivepacket(Logger *log, Socket sock, IP_Port *ip_port, uint8_t *da
 {
     memset(ip_port, 0, sizeof(IP_Port));
     struct sockaddr_storage addr;
-#if defined(_WIN32) || defined(__WIN32__) || defined (WIN32)
+#ifdef OS_WIN32
     int addrlen = sizeof(addr);
 #else
     socklen_t addrlen = sizeof(addr);
 #endif
     *length = 0;
-    int fail_or_len = recvfrom(sock, (char *) data, MAX_UDP_PACKET_SIZE, 0, (struct sockaddr *)&addr, &addrlen);
+    int fail_or_len = recvfrom(sock.socket, (char *) data, MAX_UDP_PACKET_SIZE, 0, (struct sockaddr *)&addr, &addrlen);
 
     if (fail_or_len < 0) {
         int error = net_error();
@@ -597,7 +667,7 @@ int networking_at_startup(void)
 
 #endif/*VANILLA_NACL*/
 
-#if defined(_WIN32) || defined(__WIN32__) || defined (WIN32)
+#ifdef OS_WIN32
     WSADATA wsaData;
 
     if (WSAStartup(MAKEWORD(2, 2), &wsaData) != NO_ERROR) {
@@ -614,7 +684,7 @@ int networking_at_startup(void)
 #if 0
 static void at_shutdown(void)
 {
-#if defined(_WIN32) || defined(__WIN32__) || defined (WIN32)
+#ifdef OS_WIN32
     WSACleanup();
 #endif
 }
@@ -703,12 +773,12 @@ Networking_Core *new_networking_ex(Logger *log, IP ip, uint16_t port_from, uint1
     /* Functions to increase the size of the send and receive UDP buffers.
      */
     int n = 1024 * 1024 * 2;
-    setsockopt(temp->sock, SOL_SOCKET, SO_RCVBUF, (const char *)&n, sizeof(n));
-    setsockopt(temp->sock, SOL_SOCKET, SO_SNDBUF, (const char *)&n, sizeof(n));
+    setsockopt(temp->sock.socket, SOL_SOCKET, SO_RCVBUF, (const char *)&n, sizeof(n));
+    setsockopt(temp->sock.socket, SOL_SOCKET, SO_SNDBUF, (const char *)&n, sizeof(n));
 
     /* Enable broadcast on socket */
     int broadcast = 1;
-    setsockopt(temp->sock, SOL_SOCKET, SO_BROADCAST, (const char *)&broadcast, sizeof(broadcast));
+    setsockopt(temp->sock.socket, SOL_SOCKET, SO_BROADCAST, (const char *)&broadcast, sizeof(broadcast));
 
     /* iOS UDP sockets are weird and apparently can SIGPIPE */
     if (!set_socket_nosigpipe(temp->sock)) {
@@ -776,7 +846,7 @@ Networking_Core *new_networking_ex(Logger *log, IP ip, uint16_t port_from, uint1
         mreq.ipv6mr_multiaddr.s6_addr[ 1] = 0x02;
         mreq.ipv6mr_multiaddr.s6_addr[15] = 0x01;
         mreq.ipv6mr_interface = 0;
-        int res = setsockopt(temp->sock, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP, (const char *)&mreq, sizeof(mreq));
+        const int res = setsockopt(temp->sock.socket, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP, (const char *)&mreq, sizeof(mreq));
 
         int neterror = net_error();
         const char *strerror = net_new_strerror(neterror);
@@ -806,7 +876,7 @@ Networking_Core *new_networking_ex(Logger *log, IP ip, uint16_t port_from, uint1
     int tries;
 
     for (tries = port_from; tries <= port_to; tries++) {
-        int res = bind(temp->sock, (struct sockaddr *)&addr, addrsize);
+        int res = bind(temp->sock.socket, (struct sockaddr *)&addr, addrsize);
 
         if (!res) {
             temp->port = *portptr;
@@ -1290,7 +1360,7 @@ int net_connect(Socket sock, IP_Port ip_port)
         return 0;
     }
 
-    return connect(sock, (struct sockaddr *)&addr, addrsize);
+    return connect(sock.socket, (struct sockaddr *)&addr, addrsize);
 }
 
 int32_t net_getipport(const char *node, IP_Port **res, int tox_type)
@@ -1391,41 +1461,7 @@ int bind_to_port(Socket sock, int family, uint16_t port)
         return 0;
     }
 
-    return (bind(sock, (struct sockaddr *)&addr, addrsize) == 0);
-}
-
-static int make_tox_family(int family)
-{
-    switch (family) {
-        case AF_INET:
-            return TOX_AF_INET;
-
-        case AF_INET6:
-            return TOX_AF_INET6;
-
-        case AF_UNSPEC:
-            return TOX_AF_UNSPEC;
-
-        default:
-            return family;
-    }
-}
-
-static int make_family(int tox_family)
-{
-    switch (tox_family) {
-        case TOX_AF_INET:
-            return AF_INET;
-
-        case TOX_AF_INET6:
-            return AF_INET6;
-
-        case TOX_AF_UNSPEC:
-            return AF_UNSPEC;
-
-        default:
-            return tox_family;
-    }
+    return bind(sock.socket, (struct sockaddr *)&addr, addrsize) == 0;
 }
 
 static int make_socktype(int type)
@@ -1456,12 +1492,47 @@ static int make_proto(int proto)
     }
 }
 
-Socket net_socket(int domain, int type, int protocol)
+Socket net_socket(Family domain, int type, int protocol)
 {
-    int platform_domain = make_family(domain);
-    int platform_type = make_socktype(type);
-    int platform_prot = make_proto(protocol);
-    return socket(platform_domain, platform_type, platform_prot);
+    const int platform_domain = make_family(domain);
+    const int platform_type = make_socktype(type);
+    const int platform_prot = make_proto(protocol);
+    const Socket sock = {(int)socket(platform_domain, platform_type, platform_prot)};
+    return sock;
+}
+
+int net_send(Socket sock, const void *buf, size_t len)
+{
+    return send(sock.socket, (const char *)buf, len, MSG_NOSIGNAL);
+}
+
+int net_recv(Socket sock, void *buf, size_t len)
+{
+    return recv(sock.socket, (char *)buf, len, MSG_NOSIGNAL);
+}
+
+int net_listen(Socket sock, int backlog)
+{
+    return listen(sock.socket, backlog);
+}
+
+Socket net_accept(Socket sock)
+{
+    const Socket newsock = {accept(sock.socket, nullptr, nullptr)};
+    return newsock;
+}
+
+size_t net_socket_data_recv_buffer(Socket sock)
+{
+#ifdef OS_WIN32
+    unsigned long count = 0;
+    ioctlsocket(sock.socket, FIONREAD, &count);
+#else
+    int count = 0;
+    ioctl(sock.socket, FIONREAD, &count);
+#endif
+
+    return count;
 }
 
 uint32_t net_htonl(uint32_t hostlong)
diff --git a/toxcore/network.h b/toxcore/network.h
index 10ddef02..bdfebd7e 100644
--- a/toxcore/network.h
+++ b/toxcore/network.h
@@ -24,54 +24,55 @@
 #ifndef NETWORK_H
 #define NETWORK_H
 
-#ifdef PLAN9
-#include <u.h> // Plan 9 requires this is imported first
-// Comment line here to avoid reordering by source code formatters.
-#include <libc.h>
-#endif
-
-#include "ccompat.h"
 #include "logger.h"
 
-#include <stdbool.h>
-#include <stdint.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <time.h>
-
-#if defined(_WIN32) || defined(__WIN32__) || defined (WIN32) /* Put win32 includes here */
-#ifndef WINVER
-//Windows XP
-#define WINVER 0x0501
-#endif
-
-// The mingw32/64 Windows library warns about including winsock2.h after
-// windows.h even though with the above it's a valid thing to do. So, to make
-// mingw32 headers happy, we include winsock2.h first.
-#include <winsock2.h>
-
-#include <windows.h>
-#include <ws2tcpip.h>
-
-#else // UNIX includes
-
-#include <sys/socket.h>
-#include <netinet/in.h>
-#include <arpa/inet.h>
-#include <netdb.h>
-#include <unistd.h>
-
-#endif
+#include <stdbool.h>    // bool
+#include <stddef.h>     // size_t
+#include <stdint.h>     // uint*_t
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-typedef short Family;
+typedef uint8_t Family;
 
-typedef int Socket;
-Socket net_socket(int domain, int type, int protocol);
+typedef struct Socket {
+    int socket;
+} Socket;
+
+Socket net_socket(Family domain, int type, int protocol);
+
+/* Check if socket is valid.
+ *
+ * return 1 if valid
+ * return 0 if not valid
+ */
+int sock_valid(Socket sock);
+
+extern const Socket net_invalid_socket;
+
+/**
+ * Calls send(sockfd, buf, len, MSG_NOSIGNAL).
+ */
+int net_send(Socket sockfd, const void *buf, size_t len);
+/**
+ * Calls recv(sockfd, buf, len, MSG_NOSIGNAL).
+ */
+int net_recv(Socket sockfd, void *buf, size_t len);
+/**
+ * Calls listen(sockfd, backlog).
+ */
+int net_listen(Socket sockfd, int backlog);
+/**
+ * Calls accept(sockfd, nullptr, nullptr).
+ */
+Socket net_accept(Socket sockfd);
+
+/**
+ * return the amount of data in the tcp recv buffer.
+ * return 0 on failure.
+ */
+size_t net_socket_data_recv_buffer(Socket sock);
 
 #define MAX_UDP_PACKET_SIZE 2048
 
@@ -326,13 +327,6 @@ uint16_t net_port(const Networking_Core *net);
  */
 int networking_at_startup(void);
 
-/* Check if socket is valid.
- *
- * return 1 if valid
- * return 0 if not valid
- */
-int sock_valid(Socket sock);
-
 /* Close the socket.
  */
 void kill_sock(Socket sock);
diff --git a/toxcore/onion.c b/toxcore/onion.c
index 740c25ce..476f76e9 100644
--- a/toxcore/onion.c
+++ b/toxcore/onion.c
@@ -3,7 +3,7 @@
  */
 
 /*
- * Copyright © 2016-2017 The TokTok team.
+ * Copyright © 2016-2018 The TokTok team.
  * Copyright © 2013 Tox project.
  *
  * This file is part of Tox, the free peer to peer instant messenger.
@@ -27,6 +27,9 @@
 
 #include "onion.h"
 
+#include <stdlib.h>
+#include <string.h>
+
 #include "util.h"
 
 #define RETURN_1 ONION_RETURN_1
diff --git a/toxcore/onion_announce.c b/toxcore/onion_announce.c
index 8e49f7bd..5aec3492 100644
--- a/toxcore/onion_announce.c
+++ b/toxcore/onion_announce.c
@@ -27,6 +27,9 @@
 
 #include "onion_announce.h"
 
+#include <stdlib.h>
+#include <string.h>
+
 #include "LAN_discovery.h"
 #include "util.h"
 
diff --git a/toxcore/onion_client.c b/toxcore/onion_client.c
index c4eb3fc1..3ee3e0ca 100644
--- a/toxcore/onion_client.c
+++ b/toxcore/onion_client.c
@@ -28,6 +28,9 @@
 
 #include "onion_client.h"
 
+#include <stdlib.h>
+#include <string.h>
+
 #include "LAN_discovery.h"
 #include "util.h"
 
diff --git a/toxcore/ping.c b/toxcore/ping.c
index bede07a1..cc77f2b1 100644
--- a/toxcore/ping.c
+++ b/toxcore/ping.c
@@ -29,13 +29,14 @@
 
 #include "ping.h"
 
+#include <stdlib.h>
+#include <string.h>
+
 #include "DHT.h"
 #include "network.h"
 #include "ping_array.h"
 #include "util.h"
 
-#include <stdint.h>
-
 #define PING_NUM_MAX 512
 
 /* Maximum newly announced nodes to ping per TIME_TO_PING seconds. */
diff --git a/toxcore/ping_array.c b/toxcore/ping_array.c
index a54ebfe2..bcab9fe2 100644
--- a/toxcore/ping_array.c
+++ b/toxcore/ping_array.c
@@ -27,6 +27,9 @@
 
 #include "ping_array.h"
 
+#include <stdlib.h>
+#include <string.h>
+
 #include "crypto_core.h"
 #include "util.h"
 
diff --git a/toxcore/tox.c b/toxcore/tox.c
index 3db2bd35..6b50c5e8 100644
--- a/toxcore/tox.c
+++ b/toxcore/tox.c
@@ -31,6 +31,8 @@
 typedef struct Messenger Tox;
 #include "tox.h"
 
+#include <string.h>
+
 #include "Messenger.h"
 #include "group.h"
 #include "logger.h"
diff --git a/toxcore/util.c b/toxcore/util.c
index b7a8fda6..082e453f 100644
--- a/toxcore/util.c
+++ b/toxcore/util.c
@@ -36,6 +36,7 @@
 #include "crypto_core.h" /* for CRYPTO_PUBLIC_KEY_SIZE */
 #include "network.h" /* for current_time_monotonic */
 
+#include <string.h>
 #include <time.h>
 
 
diff --git a/toxencryptsave/toxencryptsave.c b/toxencryptsave/toxencryptsave.c
index b83d6f1c..c1300348 100644
--- a/toxencryptsave/toxencryptsave.c
+++ b/toxencryptsave/toxencryptsave.c
@@ -40,6 +40,7 @@
 #include <sodium.h>
 #endif
 
+#include <stdlib.h>
 #include <string.h>
 
 #if TOX_PASS_SALT_LENGTH != crypto_pwhash_scryptsalsa208sha256_SALTBYTES