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ipcp: try to re-send CHAP ack on timeout

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If it was lost, some clients (e.g. pppd) may not try to re-send their CHAP reply.
This commit is contained in:
Samuel Thibault 2025-03-30 20:37:29 +02:00
parent b3b052a483
commit 366faaea76
3 changed files with 24 additions and 10 deletions
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7
l2tpns.c
View file

@ -5488,6 +5488,11 @@ static void regular_cleanups(double period)
if (sess_local[s].ipcp.conf_sent < config->ppp_max_configure)
{
LOG(3, s, session[s].tunnel, "No ACK for IPCP ConfigReq... resending\n");
if (sess_local[s].lcp_authtype == AUTHCHAP && sess_local[s].ipcp.conf_sent % 3 == 2)
{
LOG(3, s, session[s].tunnel, "Trying to re-send CHAP ack\n");
resendchapack(s, session[s].tunnel, sess_local[s].auth_id);
}
sendipcp(s, session[s].tunnel);
change_state(s, ipcp, next_state);
}
@ -7780,7 +7785,7 @@ int sessionsetup(sessionidt s, tunnelidt t)
// Add the route for this session.
routesset(s, &session[s], 1);
sess_local[s].lcp_authtype = 0; // RADIUS authentication complete
sess_local[s].lcp_authdone = 1; // RADIUS authentication complete
lcp_open(s, t); // transition to Network phase and send initial IPCP
// Run the plugin's against this new session.

3
l2tpns.h
View file

@ -419,6 +419,8 @@ typedef struct
// authentication to use
int lcp_authtype;
// whether authentication is over
int lcp_authdone;
// Last Received LCP ConfReq and its length
uint8_t lcp_last_received_confreq[MAXLCPLENGTH];
@ -998,6 +1000,7 @@ void processmpframe(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l, uint8_t e
void processipv6in(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l);
void processccp(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l);
void sendchap(sessionidt s, tunnelidt t);
void resendchapack(sessionidt s, tunnelidt t, uint16_t auth_id);
uint8_t *makeppp(uint8_t *b, int size, uint8_t *p, int l, sessionidt s, tunnelidt t, uint16_t mtype, uint8_t prio, bundleidt bid, uint8_t mp_bits);
uint8_t *opt_makeppp(uint8_t *p, int l, sessionidt s, tunnelidt t, uint16_t mtype, uint8_t prio, bundleidt bid, uint8_t mp_bits);
void sendlcp(sessionidt s, tunnelidt t);

24
ppp.c
View file

@ -170,6 +170,19 @@ void processpap(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l)
}
}
// Re-send a CHAP ack, in case it was previously lost
void resendchapack(sessionidt s, tunnelidt t, uint16_t auth_id)
{
uint8_t b[MAXETHER];
uint8_t *p;
p = makeppp(b, sizeof(b), 0, 0, s, t, PPPCHAP, 0, 0, 0);
if (!p) return;
*p = 3; // ack
p[1] = auth_id;
*(uint16_t *) (p + 2) = ntohs(4); // no message
tunnelsend(b, (p - b) + 4, t); // send it
}
// Process CHAP messages
void processchap(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l)
{
@ -209,15 +222,8 @@ void processchap(sessionidt s, tunnelidt t, uint8_t *p, uint16_t l)
{
if (session[s].ppp.phase == Network)
{
uint8_t b[MAXETHER];
uint8_t *p2;
LOG(2, s, t, "CHAP in Network phase, peer probably missed our ack, confirming it\n");
p2 = makeppp(b, sizeof(b), 0, 0, s, t, PPPCHAP, 0, 0, 0);
if (!p2) return;
*p2 = 3; // ack
p2[1] = p[1];
*(uint16_t *) (p2 + 2) = ntohs(4); // no message
tunnelsend(b, (p2 - b) + 4, t); // send it
resendchapack(s, t, p[1]);
}
else
LOG(2, s, t, "CHAP ignored in %s phase\n", ppp_phase(session[s].ppp.phase));
@ -405,7 +411,7 @@ static void dumplcp(uint8_t *p, int l)
void lcp_open(sessionidt s, tunnelidt t)
{
// transition to Authentication or Network phase:
session[s].ppp.phase = sess_local[s].lcp_authtype ? Authenticate : Network;
session[s].ppp.phase = sess_local[s].lcp_authtype && !sess_local[s].lcp_authdone ? Authenticate : Network;
LOG(3, s, t, "LCP: Opened, phase %s\n", ppp_phase(session[s].ppp.phase));