lwip/doc/ppp.txt
2015-03-08 14:15:20 +01:00

379 lines
10 KiB
Plaintext

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) {
struct netif *pppif = ppp_netif(pcb);
LWIP_UNUSED_ARG(ctx);
switch(err_code) {
case PPPERR_NONE: {
#if LWIP_DNS
ip_addr_t ns;
#endif /* LWIP_DNS */
printf("status_cb: Connected\n");
#if PPP_IPV4_SUPPORT
printf(" our_ipaddr = %s\n", ipaddr_ntoa(&pppif->ip_addr));
printf(" his_ipaddr = %s\n", ipaddr_ntoa(&pppif->gw));
printf(" netmask = %s\n", ipaddr_ntoa(&pppif->netmask));
#if LWIP_DNS
ns = dns_getserver(0);
printf(" dns1 = %s\n", ipaddr_ntoa(&ns));
ns = dns_getserver(1);
printf(" dns2 = %s\n", ipaddr_ntoa(&ns));
#endif /* LWIP_DNS */
#endif /* PPP_IPV4_SUPPORT */
#if PPP_IPV6_SUPPORT
printf(" our6_ipaddr = %s\n", ip6addr_ntoa(netif_ip6_addr(pppif, 0)));
#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: {
printf("status_cb: Unknown error code %d\n", err_code);
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_connect(pcb, 30);
}
/*
* Creating a new PPPoS session
* ============================
*
* In lwIP, PPPoS is not PPPoSONET, in lwIP PPPoS is PPPoSerial.
*/
#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_connect(ppp, holdoff);
/*
* 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);
/*
* 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.
/*
* 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_connect(), 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 serial 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.
* DNS servers are now only remotely asked if LWIP_DNS is set and we are now
unconditionally registering them, which is probably the wanted behavior in
almost all cases. If you need it conditional contact us and we will made it
conditional.