From f741a88b80ffcf4de65b91ff82fc9f7865cbad0e Mon Sep 17 00:00:00 2001
From: Leso_KN <info@lesosoftware.com>
Date: Mon, 23 Oct 2023 20:27:01 +0200
Subject: [PATCH] feat(tcp): Add 'bindtodevice' option (#408)

---
 src/options.c | 27 +++++++++++++++++++++++++++
 src/options.h |  3 +++
 src/tcp.c     |  2 ++
 3 files changed, 32 insertions(+)

diff --git a/src/options.c b/src/options.c
index 657947c..3856797 100644
--- a/src/options.c
+++ b/src/options.c
@@ -54,6 +54,33 @@ int opt_meth_getoption(lua_State *L, p_opt opt, p_socket ps)
     return opt->func(L, ps);
 }
 
+/*------------------------------------------------------*/
+/* binds socket to network interface */
+int opt_set_bindtodevice(lua_State *L, p_socket ps)
+{
+#ifdef __APPLE__
+    return luaL_error(L, "SO_BINDTODEVICE is not supported on this operating system");
+#else
+    const char *dev = luaL_checkstring(L, 3);
+    return opt_set(L, ps, SOL_SOCKET, SO_BINDTODEVICE, (char*)dev, strlen(dev)+1);
+#endif
+}
+
+int opt_get_bindtodevice(lua_State *L, p_socket ps)
+{
+#ifdef __APPLE__
+    return luaL_error(L, "SO_BINDTODEVICE is not supported on this operating system");
+#else
+    char dev[IFNAMSIZ];
+    int len = sizeof(dev);
+    int err = opt_get(L, ps, SOL_SOCKET, SO_BINDTODEVICE, &dev, &len);
+    if (err)
+        return err;
+    lua_pushstring(L, dev);
+    return 1;
+#endif
+}
+
 /*------------------------------------------------------*/
 /* enables reuse of local address */
 int opt_set_reuseaddr(lua_State *L, p_socket ps)
diff --git a/src/options.h b/src/options.h
index 456eeb5..26d6f02 100644
--- a/src/options.h
+++ b/src/options.h
@@ -53,6 +53,9 @@ int opt_get_tcp_keepintvl(lua_State *L, p_socket ps);
 int opt_set_tcp_defer_accept(lua_State *L, p_socket ps);
 #endif
 
+int opt_set_bindtodevice(lua_State *L, p_socket ps);
+int opt_get_bindtodevice(lua_State *L, p_socket ps);
+
 int opt_set_keepalive(lua_State *L, p_socket ps);
 int opt_get_keepalive(lua_State *L, p_socket ps);
 
diff --git a/src/tcp.c b/src/tcp.c
index e84db84..f001206 100644
--- a/src/tcp.c
+++ b/src/tcp.c
@@ -71,6 +71,7 @@ static luaL_Reg tcp_methods[] = {
 
 /* socket option handlers */
 static t_opt optget[] = {
+    {"bindtodevice", opt_get_bindtodevice},
     {"keepalive",   opt_get_keepalive},
     {"reuseaddr",   opt_get_reuseaddr},
     {"reuseport",   opt_get_reuseport},
@@ -92,6 +93,7 @@ static t_opt optget[] = {
 };
 
 static t_opt optset[] = {
+    {"bindtodevice", opt_set_bindtodevice},
     {"keepalive",   opt_set_keepalive},
     {"reuseaddr",   opt_set_reuseaddr},
     {"reuseport",   opt_set_reuseport},