Update LwIP from ESP-IDF 3.2.2 to ESP-IDF 3.3

CMakeLists.txt

@@ -1,5 +1,6 @@
 set(COMPONENT_ADD_INCLUDEDIRS
     include/apps
+    include/apps/sntp
     lwip/src/include
     port/esp32/include
     port/esp32/include/arch
@@ -9,6 +10,7 @@ set(COMPONENT_ADD_INCLUDEDIRS
 set(COMPONENT_SRCS "apps/dhcpserver/dhcpserver.c"
                    "apps/ping/esp_ping.c"
                    "apps/ping/ping.c"
+                   "apps/sntp/sntp.c"
                    "lwip/src/api/api_lib.c"
                    "lwip/src/api/api_msg.c"
                    "lwip/src/api/err.c"
@@ -84,6 +86,7 @@ set(COMPONENT_SRCS "apps/dhcpserver/dhcpserver.c"
                    "port/esp32/vfs_lwip.c"
                    "port/esp32/debug/lwip_debug.c"
                    "port/esp32/freertos/sys_arch.c"
+                   "port/esp32/netif/dhcp_state.c"
                    "port/esp32/netif/ethernetif.c"
                    "port/esp32/netif/wlanif.c")
 
@@ -121,7 +124,9 @@ if(CONFIG_PPP_SUPPORT)
 endif()
 
 set(COMPONENT_REQUIRES vfs)
-set(COMPONENT_PRIV_REQUIRES ethernet tcpip_adapter)
+set(COMPONENT_PRIV_REQUIRES ethernet tcpip_adapter nvs_flash)
+
+set(COMPONENT_ADD_LDFRAGMENTS linker.lf)
 
 register_component()
 

CONTRIBUTING.md

@@ -0,0 +1,24 @@
+# How to Contribute
+
+We'd love to accept your patches and contributions to this project. There are
+just a few small guidelines you need to follow.
+
+## Contributor License Agreement
+
+Contributions to this project must be accompanied by a Contributor License
+Agreement. You (or your employer) retain the copyright to your contribution;
+this simply gives us permission to use and redistribute your contributions as
+part of the project. Head over to <https://cla.developers.google.com/> to see
+your current agreements on file or to sign a new one.
+
+You generally only need to submit a CLA once, so if you've already submitted one
+(even if it was for a different project), you probably don't need to do it
+again.
+
+## Code reviews
+
+All submissions, including submissions by project members, require review. We
+use GitHub pull requests for this purpose. Consult
+[GitHub Help](https://help.github.com/articles/about-pull-requests/) for more
+information on using pull requests.
+