lwip/doc/ppp.txt

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PPP interface for lwIP
Author: Sylvain Rochet
Table of Contents:
1 - Supported PPP protocols and features
2 - Raw API PPP example for all protocols
3 - PPPoS input path (raw API and thread safe API)
4 - Thread safe PPP API (PPPAPI)
5 - Upgrading from lwIP <= 1.4.x to lwIP >= 1.5.x
1 Supported PPP protocols and features
======================================
Supported Low level protocols:
* PPP over serial using HDLC-like framing, such as wired dialup modems
or mobile telecommunications GPRS/EDGE/UMTS/HSPA+/LTE modems
* PPP over Ethernet, such as xDSL modems
* PPP over L2TP (Layer 2 Tunneling Protocol) LAC (L2TP Access Concentrator),
IP tunnel over UDP, such as VPN access
Supported auth protocols:
* PAP, Password Authentication Protocol
* CHAP, Challenge-Handshake Authentication Protocol, also known as CHAP-MD5
* MSCHAPv1, Microsoft version of CHAP, version 1
* MSCHAPv2, Microsoft version of CHAP, version 2
* EAP, Extensible Authentication Protocol
Supported address protocols:
* IPCP, IP Control Protocol, IPv4 addresses negotiation
* IP6CP, IPv6 Control Protocol, IPv6 link-local addresses negotiation
Supported compression or miscellaneous protocols, for serial links only:
* PFC, Protocol Field Compression
* ACFC, Address-and-Control-Field-Compression
* ACCM, Asynchronous-Control-Character-Map
* VJ, Van Jacobson TCP/IP Header Compression
2 Raw API PPP example for all protocols
=======================================
As usual, raw API for lwIP means the lightweight API which *MUST* only be used
for NO_SYS=1 systems or called inside lwIP core thread for NO_SYS=0 systems.
/*
* Globals
* =======
*/
/* The PPP control block */
ppp_pcb *ppp;
/* The PPP IP interface */
struct netif ppp_netif;
/*
* PPP status callback
* ===================
*
* PPP status callback is called on PPP status change (up, down, …) from lwIP
* core thread
*/
/* PPP status callback example */
static void status_cb(ppp_pcb *pcb, int err_code, void *ctx) {
LWIP_UNUSED_ARG(ctx);
switch(err_code) {
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case PPPERR_NONE: {
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struct ppp_addrs *ppp_addrs = ppp_addrs(pcb);
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printf("status_cb: Connected\n");
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printf(" our_ipaddr = %s\n", ip_ntoa(&ppp_addrs->our_ipaddr));
printf(" his_ipaddr = %s\n", ip_ntoa(&ppp_addrs->his_ipaddr));
printf(" netmask = %s\n", ip_ntoa(&ppp_addrs->netmask));
printf(" dns1 = %s\n", ip_ntoa(&ppp_addrs->dns1));
printf(" dns2 = %s\n", ip_ntoa(&ppp_addrs->dns2));
#if PPP_IPV6_SUPPORT
printf(" our6_ipaddr = %s\n", ip6addr_ntoa(&ppp_addrs->our6_ipaddr));
printf(" his6_ipaddr = %s\n", ip6addr_ntoa(&ppp_addrs->his6_ipaddr));
#endif /* PPP_IPV6_SUPPORT */
break;
}
case PPPERR_PARAM: {
printf("status_cb: Invalid parameter\n");
break;
}
case PPPERR_OPEN: {
printf("status_cb: Unable to open PPP session\n");
break;
}
case PPPERR_DEVICE: {
printf("status_cb: Invalid I/O device for PPP\n");
break;
}
case PPPERR_ALLOC: {
printf("status_cb: Unable to allocate resources\n");
break;
}
case PPPERR_USER: {
printf("status_cb: User interrupt\n");
break;
}
case PPPERR_CONNECT: {
printf("status_cb: Connection lost\n");
break;
}
case PPPERR_AUTHFAIL: {
printf("status_cb: Failed authentication challenge\n");
break;
}
case PPPERR_PROTOCOL: {
printf("status_cb: Failed to meet protocol\n");
break;
}
case PPPERR_PEERDEAD: {
printf("status_cb: Connection timeout\n");
break;
}
case PPPERR_IDLETIMEOUT: {
printf("status_cb: Idle Timeout\n");
break;
}
case PPPERR_CONNECTTIME: {
printf("status_cb: Max connect time reached\n");
break;
}
case PPPERR_LOOPBACK: {
printf("status_cb: Loopback detected\n");
break;
}
default: {
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printf("status_cb: Unknown error code %d\n", err_code);
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break;
}
}
/*
* This should be in the switch case, this is put outside of the switch
* case for example readability.
*/
if (err_code == PPPERR_NONE) {
return;
}
/* ppp_close() was previously called, don't reconnect */
if (err_code == PPPERR_USER) {
/* ppp_free(); -- can be called here */
return;
}
/*
* Try to reconnect in 30 seconds, if you need a modem chatscript you have
* to do a much better signaling here ;-)
*/
ppp_open(pcb, 30);
}
/*
* Creating a new PPPoS session
* ============================
*
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* In lwIP, PPPoS is not PPPoSONET, in lwIP PPPoS is PPPoSerial.
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*/
#include "netif/ppp/pppos.h"
/*
* Create a new PPPoS interface
*
* ppp_netif, netif to use for this PPP link, i.e. PPP IP interface
* ppp_sio, handler to your SIO port (see include/lwip/sio.h)
* status_cb, PPP status callback, called on PPP status change (up, down, …)
* ctx_cb, optional user-provided callback context pointer
*/
ppp = pppos_create(&ppp_netif,
ppp_sio,
status_cb, ctx_cb);
/*
* Creating a new PPPoE session
* ============================
*/
#include "netif/ppp/pppoe.h"
/*
* Create a new PPPoE interface
*
* ppp_netif, netif to use for this PPP link, i.e. PPP IP interface
* ethif, already existing and setup Ethernet interface to use
* service_name, PPPoE service name discriminator (not supported yet)
* concentrator_name, PPPoE concentrator name discriminator (not supported yet)
* status_cb, PPP status callback, called on PPP status change (up, down, …)
* ctx_cb, optional user-provided callback context pointer
*/
ppp = pppoe_create(&ppp_netif,
&ethif,
service_name, concentrator_name,
status_cb, ctx_cb);
/*
* Creating a new PPPoL2TP session
* ===============================
*/
#include "netif/ppp/pppol2tp.h"
/*
* Create a new PPPoL2TP interface
*
* ppp_netif, netif to use for this PPP link, i.e. PPP IP interface
* netif, optional already existing and setup output netif, necessary if you
* want to set this interface as default route to settle the chicken
* and egg problem with VPN links
* ipaddr, IP to connect to
* port, UDP port to connect to (usually 1701)
* secret, L2TP secret to use
* secret_len, size in bytes of the L2TP secret
* status_cb, PPP status callback, called on PPP status change (up, down, …)
* ctx_cb, optional user-provided callback context pointer
*/
ppp = pppol2tp_create(&ppp_netif,
struct netif *netif, ip_addr_t *ipaddr, u16_t port,
u8_t *secret, u8_t secret_len,
ppp_link_status_cb_fn link_status_cb, void *ctx_cb);
/*
* PPP link configuration
* ======================
*/
/* Auth configuration, this is pretty self-explanatory */
ppp_set_auth(ppp, PPPAUTHTYPE_ANY, "login", "password");
/* Set this interface as default route */
ppp_set_default(ppp);
/*
* Initiate PPP connection
* =======================
*/
/*
* Initiate PPP negotiation, without waiting (holdoff=0), can only be called
* if PPP session is in the dead state (i.e. disconnected).
*/
u16_t holdoff = 0;
ppp_open(ppp, holdoff);
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/*
* Closing PPP connection
* ======================
*/
/*
* Initiate the end of the PPP session, without carrier lost signal
* (nocarrier=0), meaning a clean shutdown of PPP protocols.
* You can call this function at anytime.
*/
u8_t nocarrier = 0;
ppp_close(ppp, nocarrier);
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/*
* Then you must wait your status_cb() to be called, it may takes from a few
* seconds to several tens of seconds depending on the current PPP state.
*/
/*
* Freeing a PPP connection
* ========================
*/
/*
* Free the PPP control block, can only be called if PPP session is in the
* dead state (i.e. disconnected). You need to call ppp_close() before.
*/
ppp_free(ppp);
3 PPPoS input path (raw API and thread safe API)
================================================
PPPoS require a serial I/O SIO port (see include/lwip/sio.h). Received data
on serial port should be sent to lwIP using the pppos_input() function.
This function is thread-safe by default if NO_SYS==0. You can alter whether
you want this function thread-safe or not using the PPP_INPROC_MULTITHREADED
setting in your lwipopts.h file.
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/*
* Fonction to call for received data
*
* ppp, PPP control block
* buffer, input buffer
* buffer_len, buffer length in bytes
*/
void pppos_input(ppp, buffer, buffer_len);
4 Thread safe PPP API (PPPAPI)
==============================
There is a thread safe API for all corresponding ppp_* functions, you have to
enable LWIP_PPP_API in your lwipopts.h file, then see include/lwip/pppapi.h,
this is actually pretty obvious.
5 Upgrading from lwIP <= 1.4.x to lwIP >= 1.5.x
===============================================
PPP API was fully reworked between 1.4.x and 1.5.x releases. However porting
from previous lwIP version is pretty easy:
* Previous PPP API used an integer to identify PPP sessions, we are now
using ppp_pcb* control block, therefore all functions changed from "int ppp"
to "ppp_pcb *ppp"
* struct netif was moved outside the PPP structure, you have to provide a netif
for PPP interface in pppoX_create() functions
* PPP session are not started automatically after you created them anymore,
you have to call ppp_open(), this way you can configure the session before
starting it.
* Previous PPP API used CamelCase, we are now using snake_case.
* Previous PPP API mixed PPPoS and PPPoE calls, this isn't the case anymore,
PPPoS functions are now prefixed pppos_ and PPPoE functions are now prefixed
pppoe_, common functions are now prefixed ppp_.
* New PPPERR_ error codes added, check you have all of them in your status
callback function
* Only the following include files should now be used in user application:
#include "lwip/pppapi.h"
#include "netif/ppp/pppos.h"
#include "netif/ppp/pppoe.h"
#include "netif/ppp/pppol2tp.h"
Functions from ppp.h can be used, but you don't need to include this header
file as it is already included by above header files.
* PPP_INPROC_OWNTHREAD was broken by design and was removed, you have to create
your own rx thread
* If you used tcpip_callback_with_block() on ppp_ functions you may wish to use
the PPPAPI API instead.
* ppp_sighup and ppp_close functions were merged using an optional argument
"nocarrier" on ppp_close.