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530 lines
15 KiB
Plaintext
530 lines
15 KiB
Plaintext
PPP interface for lwIP
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Author: Sylvain Rochet
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Table of Contents:
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1 - Supported PPP protocols and features
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2 - Raw API PPP example for all protocols
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3 - PPPoS input path (raw API, IRQ safe API, TCPIP API)
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4 - Thread safe PPP API (PPPAPI)
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5 - Notify phase callback (PPP_NOTIFY_PHASE)
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6 - Upgrading from lwIP <= 1.4.x to lwIP >= 2.0.x
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1 Supported PPP protocols and features
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======================================
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Supported Low level protocols:
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* PPP over serial using HDLC-like framing, such as wired dialup modems
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or mobile telecommunications GPRS/EDGE/UMTS/HSPA+/LTE modems
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* PPP over Ethernet, such as xDSL modems
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* PPP over L2TP (Layer 2 Tunneling Protocol) LAC (L2TP Access Concentrator),
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IP tunnel over UDP, such as VPN access
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Supported auth protocols:
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* PAP, Password Authentication Protocol
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* CHAP, Challenge-Handshake Authentication Protocol, also known as CHAP-MD5
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* MSCHAPv1, Microsoft version of CHAP, version 1
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* MSCHAPv2, Microsoft version of CHAP, version 2
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* EAP, Extensible Authentication Protocol
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Supported address protocols:
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* IPCP, IP Control Protocol, IPv4 addresses negotiation
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* IP6CP, IPv6 Control Protocol, IPv6 link-local addresses negotiation
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Supported encryption protocols:
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* MPPE, Microsoft Point-to-Point Encryption
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Supported compression or miscellaneous protocols, for serial links only:
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* PFC, Protocol Field Compression
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* ACFC, Address-and-Control-Field-Compression
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* ACCM, Asynchronous-Control-Character-Map
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* VJ, Van Jacobson TCP/IP Header Compression
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2 Raw API PPP example for all protocols
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=======================================
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As usual, raw API for lwIP means the lightweight API which *MUST* only be used
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for NO_SYS=1 systems or called inside lwIP core thread for NO_SYS=0 systems.
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/*
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* Globals
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* =======
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*/
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/* The PPP control block */
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ppp_pcb *ppp;
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/* The PPP IP interface */
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struct netif ppp_netif;
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/*
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* PPP status callback
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* ===================
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*
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* PPP status callback is called on PPP status change (up, down, …) from lwIP
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* core thread
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*/
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/* PPP status callback example */
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static void status_cb(ppp_pcb *pcb, int err_code, void *ctx) {
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struct netif *pppif = ppp_netif(pcb);
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LWIP_UNUSED_ARG(ctx);
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switch(err_code) {
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case PPPERR_NONE: {
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#if LWIP_DNS
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ip_addr_t ns;
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#endif /* LWIP_DNS */
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printf("status_cb: Connected\n");
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#if PPP_IPV4_SUPPORT
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printf(" our_ipaddr = %s\n", ipaddr_ntoa(&pppif->ip_addr));
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printf(" his_ipaddr = %s\n", ipaddr_ntoa(&pppif->gw));
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printf(" netmask = %s\n", ipaddr_ntoa(&pppif->netmask));
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#if LWIP_DNS
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ns = dns_getserver(0);
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printf(" dns1 = %s\n", ipaddr_ntoa(&ns));
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ns = dns_getserver(1);
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printf(" dns2 = %s\n", ipaddr_ntoa(&ns));
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#endif /* LWIP_DNS */
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#endif /* PPP_IPV4_SUPPORT */
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#if PPP_IPV6_SUPPORT
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printf(" our6_ipaddr = %s\n", ip6addr_ntoa(netif_ip6_addr(pppif, 0)));
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#endif /* PPP_IPV6_SUPPORT */
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break;
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}
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case PPPERR_PARAM: {
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printf("status_cb: Invalid parameter\n");
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break;
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}
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case PPPERR_OPEN: {
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printf("status_cb: Unable to open PPP session\n");
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break;
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}
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case PPPERR_DEVICE: {
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printf("status_cb: Invalid I/O device for PPP\n");
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break;
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}
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case PPPERR_ALLOC: {
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printf("status_cb: Unable to allocate resources\n");
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break;
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}
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case PPPERR_USER: {
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printf("status_cb: User interrupt\n");
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break;
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}
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case PPPERR_CONNECT: {
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printf("status_cb: Connection lost\n");
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break;
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}
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case PPPERR_AUTHFAIL: {
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printf("status_cb: Failed authentication challenge\n");
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break;
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}
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case PPPERR_PROTOCOL: {
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printf("status_cb: Failed to meet protocol\n");
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break;
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}
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case PPPERR_PEERDEAD: {
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printf("status_cb: Connection timeout\n");
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break;
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}
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case PPPERR_IDLETIMEOUT: {
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printf("status_cb: Idle Timeout\n");
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break;
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}
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case PPPERR_CONNECTTIME: {
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printf("status_cb: Max connect time reached\n");
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break;
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}
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case PPPERR_LOOPBACK: {
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printf("status_cb: Loopback detected\n");
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break;
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}
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default: {
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printf("status_cb: Unknown error code %d\n", err_code);
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break;
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}
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}
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/*
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* This should be in the switch case, this is put outside of the switch
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* case for example readability.
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*/
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if (err_code == PPPERR_NONE) {
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return;
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}
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/* ppp_close() was previously called, don't reconnect */
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if (err_code == PPPERR_USER) {
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/* ppp_free(); -- can be called here */
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return;
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}
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/*
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* Try to reconnect in 30 seconds, if you need a modem chatscript you have
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* to do a much better signaling here ;-)
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*/
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ppp_connect(pcb, 30);
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/* OR ppp_listen(pcb); */
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}
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/*
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* Creating a new PPPoS session
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* ============================
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*
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* In lwIP, PPPoS is not PPPoSONET, in lwIP PPPoS is PPPoSerial.
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*/
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#include "netif/ppp/pppos.h"
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/*
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* PPPoS serial output callback
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*
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* ppp_pcb, PPP control block
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* data, buffer to write to serial port
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* len, length of the data buffer
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* ctx, optional user-provided callback context pointer
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*
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* Return value: len if write succeed
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*/
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static u32_t output_cb(ppp_pcb *pcb, u8_t *data, u32_t len, void *ctx) {
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return uart_write(UART, data, len);
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}
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/*
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* Create a new PPPoS interface
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*
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* ppp_netif, netif to use for this PPP link, i.e. PPP IP interface
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* output_cb, PPPoS serial output callback
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* status_cb, PPP status callback, called on PPP status change (up, down, …)
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* ctx_cb, optional user-provided callback context pointer
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*/
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ppp = pppos_create(&ppp_netif,
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output_cb, status_cb, ctx_cb);
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/*
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* Creating a new PPPoE session
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* ============================
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*/
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#include "netif/ppp/pppoe.h"
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/*
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* Create a new PPPoE interface
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*
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* ppp_netif, netif to use for this PPP link, i.e. PPP IP interface
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* ethif, already existing and setup Ethernet interface to use
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* service_name, PPPoE service name discriminator (not supported yet)
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* concentrator_name, PPPoE concentrator name discriminator (not supported yet)
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* status_cb, PPP status callback, called on PPP status change (up, down, …)
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* ctx_cb, optional user-provided callback context pointer
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*/
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ppp = pppoe_create(&ppp_netif,
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ðif,
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service_name, concentrator_name,
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status_cb, ctx_cb);
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/*
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* Creating a new PPPoL2TP session
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* ===============================
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*/
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#include "netif/ppp/pppol2tp.h"
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/*
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* Create a new PPPoL2TP interface
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*
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* ppp_netif, netif to use for this PPP link, i.e. PPP IP interface
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* netif, optional already existing and setup output netif, necessary if you
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* want to set this interface as default route to settle the chicken
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* and egg problem with VPN links
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* ipaddr, IP to connect to
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* port, UDP port to connect to (usually 1701)
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* secret, L2TP secret to use
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* secret_len, size in bytes of the L2TP secret
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* status_cb, PPP status callback, called on PPP status change (up, down, …)
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* ctx_cb, optional user-provided callback context pointer
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*/
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ppp = pppol2tp_create(&ppp_netif,
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struct netif *netif, ip_addr_t *ipaddr, u16_t port,
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u8_t *secret, u8_t secret_len,
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ppp_link_status_cb_fn link_status_cb, void *ctx_cb);
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/*
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* Initiate PPP client connection
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* ==============================
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*/
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/* Set this interface as default route */
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ppp_set_default(ppp);
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/*
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* Basic PPP client configuration. Can only be set if PPP session is in the
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* dead state (i.e. disconnected). We don't need to provide thread-safe
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* equivalents through PPPAPI because those helpers are only changing
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* structure members while session is inactive for lwIP core. Configuration
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* only need to be done once.
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*/
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/* Ask the peer for up to 2 DNS server addresses. */
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ppp_set_usepeerdns(ppp, 1);
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/* Auth configuration, this is pretty self-explanatory */
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ppp_set_auth(ppp, PPPAUTHTYPE_ANY, "login", "password");
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/*
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* Initiate PPP negotiation, without waiting (holdoff=0), can only be called
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* if PPP session is in the dead state (i.e. disconnected).
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*/
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u16_t holdoff = 0;
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ppp_connect(ppp, holdoff);
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/*
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* Initiate PPP server listener
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* ============================
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*/
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/*
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* Basic PPP server configuration. Can only be set if PPP session is in the
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* dead state (i.e. disconnected). We don't need to provide thread-safe
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* equivalents through PPPAPI because those helpers are only changing
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* structure members while session is inactive for lwIP core. Configuration
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* only need to be done once.
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*/
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ip4_addr_t addr;
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/* Set our address */
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IP4_ADDR(&addr, 192,168,0,1);
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ppp_set_ipcp_ouraddr(ppp, &addr);
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/* Set peer(his) address */
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IP4_ADDR(&addr, 192,168,0,2);
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ppp_set_ipcp_hisaddr(ppp, &addr);
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/* Set primary DNS server */
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IP4_ADDR(&addr, 192,168,10,20);
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ppp_set_ipcp_dnsaddr(ppp, 0, &addr);
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/* Set secondary DNS server */
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IP4_ADDR(&addr, 192,168,10,21);
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ppp_set_ipcp_dnsaddr(ppp, 1, &addr);
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/* Auth configuration, this is pretty self-explanatory */
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ppp_set_auth(ppp, PPPAUTHTYPE_ANY, "login", "password");
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/* Require peer to authenticate */
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ppp_set_auth_required(ppp, 1);
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/*
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* Only for PPPoS, the PPP session should be up and waiting for input.
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*
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* Note: for PPPoS, ppp_connect() and ppp_listen() are actually the same thing.
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* The listen call is meant for future support of PPPoE and PPPoL2TP server
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* mode, where we will need to negotiate the incoming PPPoE session or L2TP
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* session before initiating PPP itself. We need this call because there is
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* two passive modes for PPPoS, ppp_set_passive and ppp_set_silent.
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*/
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ppp_set_silent(pppos, 1);
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/*
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* Initiate PPP listener (i.e. wait for an incoming connection), can only
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* be called if PPP session is in the dead state (i.e. disconnected).
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*/
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ppp_listen(ppp);
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/*
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* Closing PPP connection
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* ======================
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*/
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/*
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* Initiate the end of the PPP session, without carrier lost signal
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* (nocarrier=0), meaning a clean shutdown of PPP protocols.
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* You can call this function at anytime.
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*/
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u8_t nocarrier = 0;
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ppp_close(ppp, nocarrier);
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/*
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* Then you must wait your status_cb() to be called, it may takes from a few
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* seconds to several tens of seconds depending on the current PPP state.
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*/
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/*
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* Freeing a PPP connection
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* ========================
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*/
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/*
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* Free the PPP control block, can only be called if PPP session is in the
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* dead state (i.e. disconnected). You need to call ppp_close() before.
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*/
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ppp_free(ppp);
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3 PPPoS input path (raw API, IRQ safe API, TCPIP API)
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=====================================================
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Received data on serial port should be sent to lwIP using the pppos_input()
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function or the pppos_input_tcpip() function.
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If NO_SYS is 1 and if PPP_INPROC_IRQ_SAFE is 0 (the default), pppos_input()
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is not IRQ safe and then *MUST* only be called inside your main loop.
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Whatever the NO_SYS value, if PPP_INPROC_IRQ_SAFE is 1, pppos_input() is IRQ
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safe and can be safely called from an interrupt context, using that is going
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to reduce your need of buffer if pppos_input() is called byte after byte in
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your rx serial interrupt.
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if NO_SYS is 0, the thread safe way outside an interrupt context is to use
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the pppos_input_tcpip() function to pass input data to the lwIP core thread
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using the TCPIP API. This is thread safe in all cases but you should avoid
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passing data byte after byte because it uses heavy locking (mailbox) and it
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allocates pbuf, better fill them !
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if NO_SYS is 0 and if PPP_INPROC_IRQ_SAFE is 1, you may also use pppos_input()
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from an RX thread, however pppos_input() is not thread safe by itself. You can
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do that *BUT* you should NEVER call pppos_connect(), pppos_listen() and
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ppp_free() if pppos_input() can still be running, doing this is NOT thread safe
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at all. Using PPP_INPROC_IRQ_SAFE from an RX thread is discouraged unless you
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really know what you are doing, your move ;-)
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/*
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* Fonction to call for received data
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*
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* ppp, PPP control block
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* buffer, input buffer
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* buffer_len, buffer length in bytes
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*/
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void pppos_input(ppp, buffer, buffer_len);
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or
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void pppos_input_tcpip(ppp, buffer, buffer_len);
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4 Thread safe PPP API (PPPAPI)
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==============================
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There is a thread safe API for all corresponding ppp_* functions, you have to
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enable LWIP_PPP_API in your lwipopts.h file, then see
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include/netif/ppp/pppapi.h, this is actually pretty obvious.
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5 Notify phase callback (PPP_NOTIFY_PHASE)
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==========================================
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Notify phase callback, enabled using the PPP_NOTIFY_PHASE config option, let
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you configure a callback that is called on each PPP internal state change.
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This is different from the status callback which only warns you about
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up(running) and down(dead) events.
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Notify phase callback can be used, for example, to set a LED pattern depending
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on the current phase of the PPP session. Here is a callback example which
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tries to mimic what we usually see on xDSL modems while they are negotiating
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the link, which should be self-explanatory:
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static void ppp_notify_phase_cb(ppp_pcb *pcb, u8_t phase, void *ctx) {
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switch (phase) {
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/* Session is down (either permanently or briefly) */
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case PPP_PHASE_DEAD:
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led_set(PPP_LED, LED_OFF);
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break;
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/* We are between two sessions */
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case PPP_PHASE_HOLDOFF:
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led_set(PPP_LED, LED_SLOW_BLINK);
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break;
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/* Session just started */
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case PPP_PHASE_INITIALIZE:
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led_set(PPP_LED, LED_FAST_BLINK);
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break;
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/* Session is running */
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case PPP_PHASE_RUNNING:
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led_set(PPP_LED, LED_ON);
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break;
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default:
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break;
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}
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}
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6 Upgrading from lwIP <= 1.4.x to lwIP >= 2.0.x
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===============================================
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PPP API was fully reworked between 1.4.x and 2.0.x releases. However porting
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from previous lwIP version is pretty easy:
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* Previous PPP API used an integer to identify PPP sessions, we are now
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using ppp_pcb* control block, therefore all functions changed from "int ppp"
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to "ppp_pcb *ppp"
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* struct netif was moved outside the PPP structure, you have to provide a netif
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for PPP interface in pppoX_create() functions
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* PPP session are not started automatically after you created them anymore,
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you have to call ppp_connect(), this way you can configure the session before
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starting it.
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* Previous PPP API used CamelCase, we are now using snake_case.
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* Previous PPP API mixed PPPoS and PPPoE calls, this isn't the case anymore,
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PPPoS functions are now prefixed pppos_ and PPPoE functions are now prefixed
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pppoe_, common functions are now prefixed ppp_.
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* New PPPERR_ error codes added, check you have all of them in your status
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callback function
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* Only the following include files should now be used in user application:
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#include "netif/ppp/pppapi.h"
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#include "netif/ppp/pppos.h"
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#include "netif/ppp/pppoe.h"
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#include "netif/ppp/pppol2tp.h"
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Functions from ppp.h can be used, but you don't need to include this header
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file as it is already included by above header files.
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* PPP_INPROC_OWNTHREAD was broken by design and was removed, you have to create
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your own serial rx thread
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* PPP_INPROC_MULTITHREADED option was misnamed and confusing and was renamed
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PPP_INPROC_IRQ_SAFE, please read the "PPPoS input path" documentation above
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because you might have been fooled by that
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* If you used tcpip_callback_with_block() on ppp_ functions you may wish to use
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the PPPAPI API instead.
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* ppp_sighup and ppp_close functions were merged using an optional argument
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"nocarrier" on ppp_close.
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* DNS servers are now only remotely asked if LWIP_DNS is set and if
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ppp_set_usepeerdns() is set to true, they are now automatically registered
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using the dns_setserver() function so you don't need to do that in the PPP
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callback anymore.
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* PPPoS does not use the SIO API anymore, as such it now requires a serial
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output callback in place of sio_write
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* PPP_MAXIDLEFLAG is now in ms instead of jiffies
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