From e5f38bf3911dd5960231f0565ba3242534c4bc2b Mon Sep 17 00:00:00 2001 From: Sylvain Rochet Date: Sat, 21 Feb 2015 00:01:43 +0100 Subject: [PATCH] PPP, added PPP documentation --- doc/ppp.txt | 355 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 355 insertions(+) create mode 100644 doc/ppp.txt diff --git a/doc/ppp.txt b/doc/ppp.txt new file mode 100644 index 00000000..c9812087 --- /dev/null +++ b/doc/ppp.txt @@ -0,0 +1,355 @@ +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) { + case PPPERR_NONE: { /* No error. */ + struct ppp_addrs *ppp_addrs = ppp_addrs(pcb); + printf("status_cb: PPPERR_NONE\n"); + 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: { + printf("status_cb: unknown err 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_open(pcb, 30); +} + + +/* + * Creating a new PPPoS session + * ============================ + * + * In lwIP, PPPoS is not PPPoSONET, PPPoS is PPPoSerial in lwIP. + */ + +#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, + ðif, + 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). + */ +ppp_open(ppp, 0); + + +/* + * Closing PPP connection + * ====================== + */ + +/* You can call this function anytime */ +ppp_close(ppp); +/* + * 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 not thread-safe by default, setting PPP_INPROC_MULTITHREADED +to a true value in your lwipopts.h file makes pppos_input() thread safe. + +/* + * 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.