From 5074cd336d7b9f50d8e5f43afedeccad42993f8c Mon Sep 17 00:00:00 2001
From: Sebastien DUPONCHEEL <sebastien.duponcheel@ovh.net>
Date: Thu, 2 Mar 2017 17:19:40 +0100
Subject: [PATCH] mptcp: make shadowsocks kernel independant

---
 src/local.c    | 16 ++++++++++++++--
 src/netutils.h |  8 +++-----
 src/redir.c    | 16 ++++++++++++++--
 src/server.c   | 11 +++++++++--
 src/tunnel.c   | 16 ++++++++++++++--
 5 files changed, 54 insertions(+), 13 deletions(-)

diff --git a/src/local.c b/src/local.c
index 28472901..76076354 100644
--- a/src/local.c
+++ b/src/local.c
@@ -1112,11 +1112,23 @@ create_remote(listen_ctx_t *listener,
     setsockopt(remotefd, SOL_SOCKET, SO_NOSIGPIPE, &opt, sizeof(opt));
 #endif
 
-    if (listener->mptcp == 1) {
-        int err = setsockopt(remotefd, SOL_TCP, MPTCP_ENABLED, &opt, sizeof(opt));
+    if (listener->mptcp > 1) {
+        int err = setsockopt(remotefd, SOL_TCP, listener->mptcp, &opt, sizeof(opt));
         if (err == -1) {
             ERROR("failed to enable multipath TCP");
         }
+    } else if (listener->mptcp == 1) {
+        int i = 0;
+        while((listener->mptcp = mptcp_enabled_values[i]) > 0) {
+            int err = setsockopt(remotefd, SOL_TCP, listener->mptcp, &opt, sizeof(opt));
+            if (err != -1) {
+                break;
+            }
+            i++;
+        }
+        if (listener->mptcp == 0) {
+            ERROR("failed to enable multipath TCP");
+        }
     }
 
     // Setup
diff --git a/src/netutils.h b/src/netutils.h
index 95451fa1..e7dc07dc 100644
--- a/src/netutils.h
+++ b/src/netutils.h
@@ -46,13 +46,11 @@
 #endif
 #endif
 
-/* Backward compatibility for MPTCP_ENABLED between kernel 3 & 4 */
+/* MPTCP_ENABLED setsockopt values for kernel 4 & 3, best behaviour to be independant of kernel version is to test from newest to the latest values */
 #ifndef MPTCP_ENABLED
-#ifdef TCP_CC_INFO
-#define MPTCP_ENABLED 42
+static const char mptcp_enabled_values[] = { 42, 26, 0 };
 #else
-#define MPTCP_ENABLED 26
-#endif
+static const char mptcp_enabled_values[] = { MPTCP_ENABLED, 0 };
 #endif
 
 #ifndef UPDATE_INTERVAL
diff --git a/src/redir.c b/src/redir.c
index 7e69eb5a..35b29116 100644
--- a/src/redir.c
+++ b/src/redir.c
@@ -784,11 +784,23 @@ accept_cb(EV_P_ ev_io *w, int revents)
     setnonblocking(remotefd);
 
     // Enable MPTCP
-    if (listener->mptcp == 1) {
-        int err = setsockopt(remotefd, SOL_TCP, MPTCP_ENABLED, &opt, sizeof(opt));
+    if (listener->mptcp > 1) {
+        int err = setsockopt(remotefd, SOL_TCP, listener->mptcp, &opt, sizeof(opt));
         if (err == -1) {
             ERROR("failed to enable multipath TCP");
         }
+    } else if (listener->mptcp == 1) {
+        int i = 0;
+        while((listener->mptcp = mptcp_enabled_values[i]) > 0) {
+            int err = setsockopt(remotefd, SOL_TCP, listener->mptcp, &opt, sizeof(opt));
+            if (err != -1) {
+                break;
+            }
+            i++;
+        }
+        if (listener->mptcp == 0) {
+            ERROR("failed to enable multipath TCP");
+        }
     }
 
     server_t *server = new_server(serverfd);
diff --git a/src/server.c b/src/server.c
index e492b167..ff24b217 100644
--- a/src/server.c
+++ b/src/server.c
@@ -388,8 +388,15 @@ create_and_bind(const char *host, const char *port, int mptcp)
         }
 
         if (mptcp == 1) {
-            int err = setsockopt(listen_sock, SOL_TCP, MPTCP_ENABLED, &opt, sizeof(opt));
-            if (err == -1) {
+            int i = 0;
+            while((mptcp = mptcp_enabled_values[i]) > 0) {
+                int err = setsockopt(listen_sock, IPPROTO_TCP, mptcp, &opt, sizeof(opt));
+                if (err != -1) {
+                    break;
+                }
+                i++;
+            }
+            if (mptcp == 0) {
                 ERROR("failed to enable multipath TCP");
             }
         }
diff --git a/src/tunnel.c b/src/tunnel.c
index 098478a5..9c792f84 100644
--- a/src/tunnel.c
+++ b/src/tunnel.c
@@ -659,11 +659,23 @@ accept_cb(EV_P_ ev_io *w, int revents)
     setsockopt(remotefd, SOL_SOCKET, SO_NOSIGPIPE, &opt, sizeof(opt));
 #endif
 
-    if (listener->mptcp == 1) {
-        int err = setsockopt(remotefd, SOL_TCP, MPTCP_ENABLED, &opt, sizeof(opt));
+    if (listener->mptcp > 1) {
+        int err = setsockopt(remotefd, SOL_TCP, listener->mptcp, &opt, sizeof(opt));
         if (err == -1) {
             ERROR("failed to enable multipath TCP");
         }
+    } else if (listener->mptcp == 1) {
+       int i = 0;
+       while((listener->mptcp = mptcp_enabled_values[i]) > 0) {
+            int err = setsockopt(remotefd, SOL_TCP, listener->mptcp, &opt, sizeof(opt));
+            if (err != -1) {
+                break;
+            }
+            i++;
+        }
+        if (listener->mptcp == 0) {
+            ERROR("failed to enable multipath TCP");
+        }
     }
 
     // Setup