feature: makes outgoing connections to a proxied server originate from the specified local IP address with an optional port.

Author: zhuizhuhaomeng

lib/ngx/balancer.lua

@@ -24,6 +24,7 @@ local ngx_lua_ffi_balancer_set_more_tries
 local ngx_lua_ffi_balancer_get_last_failure
 local ngx_lua_ffi_balancer_set_timeouts -- used by both stream and http
 local ngx_lua_ffi_balancer_set_upstream_tls
+local ngx_lua_ffi_balancer_bind_to_local_addr
 
 
 if subsystem == 'http' then
@@ -48,8 +49,13 @@ if subsystem == 'http' then
 
     int ngx_http_lua_ffi_balancer_recreate_request(ngx_http_request_t *r,
         char **err);
+
     int ngx_http_lua_ffi_balancer_set_upstream_tls(ngx_http_request_t *r,
         int on, char **err);
+
+    int ngx_http_lua_ffi_balancer_bind_to_local_addr(ngx_http_request_t *r,
+        const u_char *addr, size_t addr_len,
+        u_char *errbuf, size_t *errbuf_size);
     ]]
 
     ngx_lua_ffi_balancer_set_current_peer =
@@ -70,6 +76,9 @@ if subsystem == 'http' then
     ngx_lua_ffi_balancer_set_upstream_tls =
         C.ngx_http_lua_ffi_balancer_set_upstream_tls
 
+    ngx_lua_ffi_balancer_bind_to_local_addr =
+        C.ngx_http_lua_ffi_balancer_bind_to_local_addr
+
 elseif subsystem == 'stream' then
     ffi.cdef[[
     int ngx_stream_lua_ffi_balancer_set_current_peer(
@@ -353,5 +362,38 @@ if subsystem == 'http' then
     end
 end
 
+if subsystem == "http" then
+    function _M.bind_to_local_addr(addr)
+        local r = get_request()
+        if not r then
+            error("no request found")
+        end
+
+        if type(addr) ~= "string" then
+            error("bad argument #1 to 'bind_to_local_addr' "
+                  .. "(string expected, got " .. type(addr) .. ")")
+        end
+
+        local errbuf_size = 1024
+        local errbuf = get_string_buf(errbuf_size)
+        local sizep = get_size_ptr()
+        sizep[0] = errbuf_size
+        local rc = ngx_lua_ffi_balancer_bind_to_local_addr(r, addr, #addr,
+                                                           errbuf,
+                                                           sizep)
+        if rc == FFI_OK then
+            return true
+        end
+
+        return nil, ffi_str(errbuf, sizep[0])
+    end
+
+else
+    function _M.bind_to_local_addr(addr)
+        error("'bind_to_local_addr' not yet implemented in " .. subsystem ..
+              " subsystem", 2)
+    end
+end
+
 
 return _M

lib/ngx/balancer.md

@@ -16,6 +16,7 @@ Table of Contents
     * [get_last_failure](#get_last_failure)
     * [recreate_request](#recreate_request)
     * [set_current_peer](#set_current_peer)
+    * [bind_to_local_addr](#bind_to_local_addr)
     * [enable_keepalive](#enable_keepalive)
     * [set_more_tries](#set_more_tries)
     * [set_timeouts](#set_timeouts)
@@ -174,6 +175,20 @@ In case of an error, this function returns `nil` and a string describing the err
 
 [Back to TOC](#table-of-contents)
 
+bind_to_local_addr
+--------------
+**syntax:** *ok, err = balancer.bind_to_local_addr(addr)*
+
+**context:** *balancer_by_lua**
+
+Makes outgoing connections to a proxied server originate from the specified local IP address with an optional port.
+
+`addr` is a string value of the IP address with optional port. For example: 127.0.0.1, 127.0.0.1:12345.
+
+In case of an error, this function returns `nil` and a string describing the error.
+
+[Back to TOC](#table-of-contents)
+
 enable_keepalive
 ----------------
 **syntax:** `ok, err = balancer.enable_keepalive(idle_timeout?, max_requests?)`