Try value 42 for mptcp (fallback to 26)

m4/pkg.m4

@@ -1,6 +1,6 @@
-dnl pkg.m4 - Macros to locate and utilise pkg-config.   -*- Autoconf -*-
-dnl serial 11 (pkg-config-0.29)
-dnl
+# pkg.m4 - Macros to locate and utilise pkg-config.   -*- Autoconf -*-
+# serial 12 (pkg-config-0.29.2)
+
 dnl Copyright © 2004 Scott James Remnant <scott@netsplit.com>.
 dnl Copyright © 2012-2015 Dan Nicholson <dbn.lists@gmail.com>
 dnl
@@ -41,7 +41,7 @@ dnl
 dnl See the "Since" comment for each macro you use to see what version
 dnl of the macros you require.
 m4_defun([PKG_PREREQ],
-[m4_define([PKG_MACROS_VERSION], [0.29])
+[m4_define([PKG_MACROS_VERSION], [0.29.2])
 m4_if(m4_version_compare(PKG_MACROS_VERSION, [$1]), -1,
     [m4_fatal([pkg.m4 version $1 or higher is required but ]PKG_MACROS_VERSION[ found])])
 ])dnl PKG_PREREQ
@@ -142,7 +142,7 @@ AC_ARG_VAR([$1][_CFLAGS], [C compiler flags for $1, overriding pkg-config])dnl
 AC_ARG_VAR([$1][_LIBS], [linker flags for $1, overriding pkg-config])dnl
 
 pkg_failed=no
-AC_MSG_CHECKING([for $1])
+AC_MSG_CHECKING([for $2])
 
 _PKG_CONFIG([$1][_CFLAGS], [cflags], [$2])
 _PKG_CONFIG([$1][_LIBS], [libs], [$2])
@@ -152,7 +152,7 @@ and $1[]_LIBS to avoid the need to call pkg-config.
 See the pkg-config man page for more details.])
 
 if test $pkg_failed = yes; then
-   	AC_MSG_RESULT([no])
+        AC_MSG_RESULT([no])
         _PKG_SHORT_ERRORS_SUPPORTED
         if test $_pkg_short_errors_supported = yes; then
 	        $1[]_PKG_ERRORS=`$PKG_CONFIG --short-errors --print-errors --cflags --libs "$2" 2>&1`
@@ -173,7 +173,7 @@ installed software in a non-standard prefix.
 _PKG_TEXT])[]dnl
         ])
 elif test $pkg_failed = untried; then
-     	AC_MSG_RESULT([no])
+        AC_MSG_RESULT([no])
 	m4_default([$4], [AC_MSG_FAILURE(
 [The pkg-config script could not be found or is too old.  Make sure it
 is in your PATH or set the PKG_CONFIG environment variable to the full

src/main.c

@@ -53,8 +53,6 @@
 #define GT_ABYTES    (16)
 #define GT_KEYBYTES  (32)
 
-#define MPTCP_ENABLED (26)
-
 static struct {
     volatile sig_atomic_t quit;
     volatile sig_atomic_t info;
@@ -116,13 +114,16 @@ enum sk_opt {
     sk_acceptfilter,
     sk_quickack,
     sk_user_timeout,
-    sk_mptcp,
+    sk_mptcp_26,
+    sk_mptcp_42,
 };
 
-static void sk_set (int fd, enum sk_opt opt, const void *val, socklen_t len)
+static int sk_set (int fd, enum sk_opt opt, const void *val, socklen_t len)
 {
-    if (!val || len<=0)
-        return;
+    if (!val || len<=0) {
+        errno = EINVAL;
+        return -1;
+    }
 
     struct {
         const char *name;
@@ -173,33 +174,44 @@ static void sk_set (int fd, enum sk_opt opt, const void *val, socklen_t len)
             1, IPPROTO_TCP, TCP_USER_TIMEOUT,
 #endif
         },
-        [sk_mptcp] = { "MPTCP_ENABLED",
-#ifdef MPTCP_ENABLED
-            1, IPPROTO_TCP, MPTCP_ENABLED,
-#endif
-        },
+        [sk_mptcp_26] = { "MPTCP_ENABLED (26)", 1, IPPROTO_TCP, 26 },
+        [sk_mptcp_42] = { "MPTCP_ENABLED (42)", 1, IPPROTO_TCP, 42 },
     };
 
     if (!opts[opt].present) {
         gt_na(opts[opt].name);
-        return;
+        errno = EINVAL;
+        return -1;
     }
 
-    if (setsockopt(fd, opts[opt].level, opts[opt].option, val, len)==-1)
+    int ret = setsockopt(fd, opts[opt].level, opts[opt].option, val, len);
+
+    if (ret==-1) {
+        int err = errno;
         gt_log("couldn't set socket option `%s'\n", opts[opt].name);
+        errno = err;
+    }
+
+    return ret;
 }
 
-static void sk_set_int (int fd, enum sk_opt opt, int val)
+static int sk_set_int (int fd, enum sk_opt opt, int val)
 {
     return sk_set(fd, opt, &val, sizeof(val));
 }
 
+static void sk_set_mptcp (int fd)
+{
+    if (sk_set_int(fd, sk_mptcp_42, 1)==-1)
+        sk_set_int(fd, sk_mptcp_26, 1);
+}
+
 static int sk_listen (int fd, struct addrinfo *ai)
 {
     sk_set_int(fd, sk_reuseaddr, 1);
 
     if (gt.mptcp)
-        sk_set_int(fd, sk_mptcp, 1);
+        sk_set_mptcp(fd);
 
     if (bind(fd, ai->ai_addr, ai->ai_addrlen)==-1) {
         perror("bind");
@@ -226,7 +238,7 @@ static int sk_connect (int fd, struct addrinfo *ai)
     fd_set_nonblock(fd);
 
     if (gt.mptcp)
-        sk_set_int(fd, sk_mptcp, 1);
+        sk_set_mptcp(fd);
 
     int ret = connect(fd, ai->ai_addr, ai->ai_addrlen);
 
@@ -1148,7 +1160,7 @@ static int gt_setup_crypto (struct crypto_ctx *ctx, int fd, int listener)
         return -1;
 
     if (memcmp(&data_r[size-hash_size-sizeof(proto)], proto, 3)) {
-        gt_log("bad packet [%02X%02X%02X] !\n",
+        gt_log("bad packet [%02"PRIX8"%02"PRIX8"%02"PRIX8"] !\n",
             &data_r[size-hash_size-sizeof(proto)+0],
             &data_r[size-hash_size-sizeof(proto)+1],
             &data_r[size-hash_size-sizeof(proto)+2]);