proxy: mcp.request improvements

- errors if a string value is missing the "\r\n" terminator
- properly uses a value from a response object
- allows passing in a request object for the value as well

- also adds r:vlen() for recovering the value length of a response

think this still needs r:flags() or similar?

3 files changed, 40 insertions, 5 deletions

diff --git a/proxy_lua.c b/proxy_lua.c
index 5f5707c..383f747 100644
--- a/proxy_lua.c
+++ b/proxy_lua.c
@@ -32,6 +32,23 @@ static int mcplib_response_hit(lua_State *L) {
     return 1;
 }
 
+// Caller needs to discern if a vlen is 0 because of a failed response or an
+// OK response that was actually zero. So we always return an integer value
+// here.
+static int mcplib_response_vlen(lua_State *L) {
+    mcp_resp_t *r = luaL_checkudata(L, -1, "mcp.response");
+
+    // We do remove the "\r\n" from the value length, so if you're actually
+    // processing the value nothing breaks.
+    if (r->resp.vlen >= 2) {
+        lua_pushinteger(L, r->resp.vlen-2);
+    } else {
+        lua_pushinteger(L, 0);
+    }
+
+    return 1;
+}
+
 static int mcplib_response_gc(lua_State *L) {
     mcp_resp_t *r = luaL_checkudata(L, -1, "mcp.response");
 
@@ -773,6 +790,7 @@ int proxy_register_libs(LIBEVENT_THREAD *t, void *ctx) {
     const struct luaL_Reg mcplib_response_m[] = {
         {"ok", mcplib_response_ok},
         {"hit", mcplib_response_hit},
+        {"vlen", mcplib_response_vlen},
         {"__gc", mcplib_response_gc},
         {NULL, NULL}
     };
diff --git a/proxy_request.c b/proxy_request.c
index 259ec90..9918499 100644
--- a/proxy_request.c
+++ b/proxy_request.c
@@ -529,13 +529,23 @@ int mcplib_request(lua_State *L) {
     int type = lua_type(L, 2);
     if (type == LUA_TSTRING) {
         val = luaL_optlstring(L, 2, NULL, &vlen);
+        if (vlen < 2 || memcmp(val+vlen-2, "\r\n", 2) != 0) {
+            proxy_lua_error(L, "value passed to mcp.request must end with \\r\\n");
+        }
     } else if (type == LUA_TUSERDATA) {
-        mcp_resp_t *r = luaL_checkudata(L, 2, "mcp.response");
-        if (r->buf) {
-            val = r->buf;
-            vlen = r->blen;
+        // vlen for requests and responses include the "\r\n" already.
+        mcp_resp_t *r = luaL_testudata(L, 2, "mcp.response");
+        if (r != NULL) {
+            if (r->resp.value) {
+                val = r->resp.value;
+                vlen = r->resp.vlen_read; // paranoia, so we can't overread into memory.
+            }
         } else {
-            // TODO (v2): other response modes unhandled.
+            mcp_request_t *rq = luaL_testudata(L, 2, "mcp.request");
+            if (rq->pr.vbuf) {
+                val = rq->pr.vbuf;
+                vlen = rq->pr.vlen;
+            }
         }
     }
 
diff --git a/t/startfile.lua b/t/startfile.lua
index c8e3806..c204d49 100644
--- a/t/startfile.lua
+++ b/t/startfile.lua
@@ -151,6 +151,10 @@ function failover_factory(zones, local_zone)
             end
             return restable[1], "failover_backup_miss"
         end
+        -- example of making a new set request on the side.
+        -- local nr = mcp.request("set /foo/asdf 0 0 " .. res:vlen() .. "\r\n", res)
+        -- local nr = mcp.request("set /foo/asdf 0 0 2\r\n", "mo\r\n")
+        -- near_zone(nr)
         return res, "failover_hit" -- send result back to client
     end
 end
@@ -172,6 +176,9 @@ function setinvalidate_factory(zones, local_zone)
         if res:ok() == true then
             -- create a new delete request
             local dr = new_req("delete /testing/" .. r:key() .. "\r\n")
+            -- example of new request from existing request
+            -- note this isn't trimming the key so it'll make a weird one.
+            -- local dr = new_req("set /bar/" .. r:key() .. " 0 0 " .. r:token(5) .. "\r\n", r)
             for _, zone in pairs(far_zones) do
                 -- NOTE: can check/do things on the specific response here.
                 zone(dr)