lua: add net.outgoing_{v4,v6} and documentation

Fixes https://gitlab.labs.nic.cz/knot/resolver/issues/158
The naming is inspired by Unbound's "outgoing-interface".

diff --git a/daemon/README.rst b/daemon/README.rst
index 8d62ab64868ebefbf3aea8dc6f6b720444bc50ab..aa8990179a7a82d9fb97acd9d1617b2d97a7cc2f 100644 (file)
--- a/daemon/README.rst
+++ b/daemon/README.rst
@@ -601,6 +601,11 @@ For when listening on ``localhost`` just doesn't cut it.
    have size of multiplies of 64 (64, 128, 192, ...).  Setting padding to
    value < 2 will disable it.
 
+.. function:: net.outgoing_v4([string address])
+
+   Get/set the IPv4 address used to perform queries.  There is also ``net.outgoing_v6`` for IPv6.
+   The default is ``nil``, which lets the OS choose any address.
+
 Trust anchors and DNSSEC
 ^^^^^^^^^^^^^^^^^^^^^^^^
 

diff --git a/daemon/bindings.c b/daemon/bindings.c
index 26969087cb1bd1b3af5417546e390ad9cc37cb7e..24f4427536f6433bf188f08cee98f36151ef3269 100644 (file)
--- a/daemon/bindings.c
+++ b/daemon/bindings.c
@@ -21,6 +21,7 @@
 
 #include "lib/cache.h"
 #include "lib/cdb.h"
+#include "lib/utils.h"
 #include "daemon/bindings.h"
 #include "daemon/worker.h"
 #include "daemon/tls.h"
@@ -421,6 +422,63 @@ static int net_tls_padding(lua_State *L)
        return 1;
 }
 
+static int net_outgoing(lua_State *L, int family)
+{
+       struct worker_ctx *worker = wrk_luaget(L);
+       union inaddr *addr;
+       if (family == AF_INET)
+               addr = (union inaddr*)&worker->out_addr4;
+       else
+               addr = (union inaddr*)&worker->out_addr6;
+
+       if (lua_gettop(L) == 0) { /* Return the current value. */
+               if (addr->ip.sa_family == AF_UNSPEC) {
+                       lua_pushnil(L);
+                       return 1;
+               }
+               if (addr->ip.sa_family != family) {
+                       assert(false);
+                       lua_error(L);
+               }
+               char addr_buf[INET6_ADDRSTRLEN];
+               int err;
+               if (family == AF_INET)
+                       err = uv_ip4_name(&addr->ip4, addr_buf, sizeof(addr_buf));
+               else
+                       err = uv_ip6_name(&addr->ip6, addr_buf, sizeof(addr_buf));
+               if (err)
+                       lua_error(L);
+               lua_pushstring(L, addr_buf);
+               return 1;
+       }
+
+       if ((lua_gettop(L) != 1) || (!lua_isstring(L, 1) && !lua_isnil(L, 1))) {
+               format_error(L, "net.outgoing_vX takes one address string parameter or nil");
+               lua_error(L);
+       }
+
+       if (lua_isnil(L, 1)) {
+               addr->ip.sa_family = AF_UNSPEC;
+               return 1;
+       }
+
+       const char *addr_str = lua_tostring(L, 1);
+       int err;
+       if (family == AF_INET)
+               err = uv_ip4_addr(addr_str, 0, &addr->ip4);
+       else
+               err = uv_ip6_addr(addr_str, 0, &addr->ip6);
+       if (err) {
+               format_error(L, "net.outgoing_vX: failed to parse the address");
+               lua_error(L);
+       }
+       lua_pushboolean(L, true);
+       return 1;
+}
+
+static int net_outgoing_v4(lua_State *L) { return net_outgoing(L, AF_INET); }
+static int net_outgoing_v6(lua_State *L) { return net_outgoing(L, AF_INET6); }
+
 int lib_net(lua_State *L)
 {
        static const luaL_Reg lib[] = {
@@ -432,6 +490,8 @@ int lib_net(lua_State *L)
                { "tcp_pipeline", net_pipeline },
                { "tls",          net_tls },
                { "tls_padding",  net_tls_padding },
+               { "outgoing_v4",  net_outgoing_v4 },
+               { "outgoing_v6",  net_outgoing_v6 },
                { NULL, NULL }
        };
        register_lib(L, "net", lib);