Hi all,
This is my first post to this mailing list. I am trying to use lwip on my LTE modem in PPP mode, which is connected to my STM32 nucleo board. I also use FreeRTOS.
I had a few issues already getting stuff up and running but I think I have most of it in the right place.
Unfortunately I am still not able to connect to a socket (routing error). I don't really know what the problem is since I lack understanding of PPP and its negotiations.
What I have so far:
- Modem in PPP mode (I think, it returns "connected" on ATD*99#, no clue what else I can do to verify if it is properly setup in PPP mode. I read other topics where they have the issue that the modem reports back "no carrier". I do NOT have that problem, so I think I am good here).
- Add my netif as "default".
- Create the pppos client, connect it, and start the main thread.
Code snippet:
// initialize lwip/tcpip
tcpip_init(tcpipInitDone, nullptr);
// Wait for lwip tcpip thread
while (!initDone)
{
}
netif_set_status_callback(&pppos_netif, netif_status_callback);
netif_set_up(&pppos_netif);
netif_set_default(&pppos_netif);
ppp = pppos_create(&pppos_netif, ppp_output_cb, ppp_link_status_cb, NULL);
if (!ppp)
{
logger.WriteDebug(LoggingCategoryModem, "PPPOS example: Could not create PPP control interface");
return;
}
ppp_connect(ppp, 0);
sys_thread_new("pppos_rx_thread", pppos_rx_thread, NULL, DEFAULT_THREAD_STACKSIZE, DEFAULT_THREAD_PRIO);
After this code ran to completion, I create and connect a socket as follows:
struct sockaddr_in addr;
addr.sin_len = sizeof(addr);
addr.sin_family = AF_INET;
addr.sin_port = PP_HTONS(SOCK_TARGET_PORT); // 80
addr.sin_addr.s_addr = inet_addr(SOCK_TARGET_HOST); // "172.217.168.238" (
google.com, just to see if I can connect to anything on the internet
auto s = lwip_socket(AF_INET, SOCK_STREAM, 0);
LWIP_ASSERT("s >= 0", s >= 0);
auto ret = lwip_connect(s, (struct sockaddr*)&addr, sizeof(addr));
LWIP_ASSERT("ret == 0", ret == 0);
The lwip_connect call returns -1. Stepping through the code I can see that the ip_route call is not satisfied with my default netif. I think because lwip never managed to get a proper IP address while negotiating with the otherside (but this is the part where I am on thin ice, I have too little knowledge about how this handshaking/negotiation process works).
I also enabled lwip logging and instead of printing via printf, I send the loggings to my uart. I get the following loggings from lwip:
netif: netmask of interface set to 255.0.0.0
netif: GW address of interface set to 127.0.0.1
netif_set_ipaddr: netif address being changed
netif: added interface lo IP addr 127.0.0.1 netmask 255.0.0.0 gw 127.0.0.1
igmp_init: initializing
dns_init: initializing
PPPNETIF: WL0 is UP
IPV4: Host at 0.0.0.0 mask 0.0.0.0 gateway 0.0.0.0
netif: setting default interface WL
netif: netmask of interface WL set to 255.255.255.255
netif: added interface pp IP addr 0.0.0.0 netmask 255.255.255.255 gw 0.0.0.0
ppp phase changed[1]: phase=0
ppp_connect[1]: holdoff=0
ppp phase changed[1]: phase=3
pppos_connect: unit 1: connecting
ppp_start[1]
ppp phase changed[1]: phase=6
pppos_send_config[1]: out_accm=FF FF FF FF
ppp_send_config[1]
pppos_recv_config[1]: in_accm=FF FF FF FF
ppp_recv_config[1]
ppp: auth protocols: PAP=0 CHAP=0 CHAP_MD5=0
pbuf_alloc(length=24)
pbuf_alloc(length=24) == 0x20010368
pbuf_alloc(length=0)
pbuf_alloc(length=0) == 0x20010258
pbuf_free(0x20010258)
pbuf_free: deallocating 0x20010258
pppos_write[1]: len=24
pbuf_free(0x20010368)
pbuf_free: deallocating 0x20010368
ppp_start[1]: finished
lwip_socket(PF_INET, SOCK_STREAM, 0) = 0
lwip_connect(0, addr=172.217.168.238 port=80)
tcp_connect to port 80
ip4_route: No route to 172.217.168.238
lwip_connect(0) failed, err=-4
lwip_send(0, data="" size=4, flags=0x0)
tcp_write(pcb=0x20011744, data="" len=4, apiflags=1)
tcp_write() called in invalid state
lwip_send(0) err=-11 written=0
dns_tmr: dns_check_entries
I have pushed my latest changes to github here:
It's a work in progress obviously, for example I commented out the part where I set the modem in PPP mode, I do this manually before I start this application on my microcontroller. Just to be more confident and to ensure PPP mode is properly set up before I start lwip.
I really hope somebody can help me out further. And my apologies if I ask stupid questions/miss something really obvious. Again, I am not experienced in the PPP area.