Added an optional parameter for ngx.req.set_header and ngx.req.clear_header that determines whether or not to replace underscores with hyphens.

Previously, underscores were replaced unconditionally.
Currently each of the functions has another boolean argument. If it's false, underscores would not be touched. If it's true, they would.
The default value of the argument is true.

Author: Aviram

src/ngx_http_lua_headers.c

@@ -581,12 +581,26 @@ ngx_http_lua_ngx_header_set(lua_State *L)
 static int
 ngx_http_lua_ngx_req_header_clear(lua_State *L)
 {
-    if (lua_gettop(L) != 1) {
-        return luaL_error(L, "expecting one arguments, but seen %d",
+    ngx_uint_t n;
+    n = lua_gettop(L);
+    if ((n != 1) && (n != 2)) {
+        return luaL_error(L, "expecting one or two arguments, but seen %d",
                           lua_gettop(L));
     }
 
-    lua_pushnil(L);
+    if (n == 2) {
+        u_char  *p;
+        size_t   len;
+        int replace_underscores = 1;
+        p = (u_char *) luaL_checklstring(L, 1, &len);
+        replace_underscores = lua_toboolean(L, 2);
+        lua_pop(L, 2);
+        lua_pushlstring(L, (char *) p, len);
+        lua_pushnil(L);
+        lua_pushboolean(L, replace_underscores);
+    } else {
+        lua_pushnil(L);
+    }
 
     return ngx_http_lua_ngx_req_header_set_helper(L);
 }
@@ -595,7 +609,7 @@ ngx_http_lua_ngx_req_header_clear(lua_State *L)
 static int
 ngx_http_lua_ngx_req_header_set(lua_State *L)
 {
-    if (lua_gettop(L) != 2) {
+    if ((lua_gettop(L) != 2) && (lua_gettop(L) != 3)) {
         return luaL_error(L, "expecting two arguments, but seen %d",
                           lua_gettop(L));
     }
@@ -615,6 +629,7 @@ ngx_http_lua_ngx_req_header_set_helper(lua_State *L)
     size_t                       len;
     ngx_int_t                    rc;
     ngx_uint_t                   n;
+    int                          replace_underscores = 1;
 
     lua_pushlightuserdata(L, &ngx_http_lua_request_key);
     lua_rawget(L, LUA_GLOBALSINDEX);
@@ -627,17 +642,26 @@ ngx_http_lua_ngx_req_header_set_helper(lua_State *L)
 
     ngx_http_lua_check_fake_request(L, r);
 
+    n = lua_gettop(L);
+    if (n >= 3) {
+        replace_underscores = lua_toboolean(L, 3);
+    } else {
+        replace_underscores = 1;
+    }
+
     p = (u_char *) luaL_checklstring(L, 1, &len);
 
     dd("key: %.*s, len %d", (int) len, p, (int) len);
 
+    if (replace_underscores) {
     /* replace "_" with "-" */
-    for (i = 0; i < len; i++) {
-        if (p[i] == '_') {
-            p[i] = '-';
+        for (i = 0; i < len; i++) {
+            if (p[i] == '_') {
+                p[i] = '-';
+            }
         }
     }
-
+    
     key.data = ngx_palloc(r->pool, len + 1);
     if (key.data == NULL) {
         return luaL_error(L, "out of memory");