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PPP, MPPE, handle packets in decompressor without address and control nor protocol

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Our PPP stack deals with packet without address and control byte nor 2-byte
protocol field, improved mppe_decompress() so we don't have to worry about
them.
This commit is contained in:
Sylvain Rochet 2015-04-12 18:41:21 +02:00
parent 0e1aec4348
commit 5f0e261f2d
1 changed files with 9 additions and 15 deletions
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24
src/netif/ppp/mppe.c
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@ -80,8 +80,8 @@ struct ppp_mppe_state {
#define MPPE_BIT_FLUSHED MPPE_BIT_A #define MPPE_BIT_FLUSHED MPPE_BIT_A
#define MPPE_BIT_ENCRYPTED MPPE_BIT_D #define MPPE_BIT_ENCRYPTED MPPE_BIT_D
#define MPPE_BITS(p) ((p)[4] & 0xf0) #define MPPE_BITS(p) ((p)[0] & 0xf0)
#define MPPE_CCOUNT(p) ((((p)[4] & 0x0f) << 8) + (p)[5]) #define MPPE_CCOUNT(p) ((((p)[0] & 0x0f) << 8) + (p)[1])
#define MPPE_CCOUNT_SPACE 0x1000 /* The size of the ccount space */ #define MPPE_CCOUNT_SPACE 0x1000 /* The size of the ccount space */
#define MPPE_OVHD 2 /* MPPE overhead/packet */ #define MPPE_OVHD 2 /* MPPE overhead/packet */
@ -377,7 +377,7 @@ mppe_decompress(void *arg, unsigned char *ibuf, int isize, unsigned char *obuf,
int flushed = MPPE_BITS(ibuf) & MPPE_BIT_FLUSHED; int flushed = MPPE_BITS(ibuf) & MPPE_BIT_FLUSHED;
int sanity = 0; int sanity = 0;
if (isize <= PPP_HDRLEN + MPPE_OVHD) { if (isize <= MPPE_OVHD) {
if (state->debug) if (state->debug)
PPPDEBUG(LOG_DEBUG, PPPDEBUG(LOG_DEBUG,
("mppe_decompress[%d]: short pkt (%d)\n", ("mppe_decompress[%d]: short pkt (%d)\n",
@ -387,17 +387,15 @@ mppe_decompress(void *arg, unsigned char *ibuf, int isize, unsigned char *obuf,
/* /*
* Make sure we have enough room to decrypt the packet. * Make sure we have enough room to decrypt the packet.
* Note that for our test we only subtract 1 byte whereas in * Note that for our test we add 1 byte to account for possible PFC.
* mppe_compress() we added 2 bytes (+MPPE_OVHD);
* this is to account for possible PFC.
*/ */
if (osize < isize - MPPE_OVHD - 1) { if (osize < isize - MPPE_OVHD + 1) {
PPPDEBUG(LOG_DEBUG, ("mppe_decompress[%d]: osize too small! " PPPDEBUG(LOG_DEBUG, ("mppe_decompress[%d]: osize too small! "
"(have: %d need: %d)\n", state->unit, "(have: %d need: %d)\n", state->unit,
osize, isize - MPPE_OVHD - 1)); osize, isize - MPPE_OVHD + 1));
return ERR_BUF; return ERR_BUF;
} }
osize = isize - MPPE_OVHD - 2; /* assume no PFC */ osize = isize - MPPE_OVHD; /* assume no PFC */
ccount = MPPE_CCOUNT(ibuf); ccount = MPPE_CCOUNT(ibuf);
if (state->debug >= 7) if (state->debug >= 7)
@ -497,12 +495,8 @@ mppe_decompress(void *arg, unsigned char *ibuf, int isize, unsigned char *obuf,
* Fill in the first part of the PPP header. The protocol field * Fill in the first part of the PPP header. The protocol field
* comes from the decrypted data. * comes from the decrypted data.
*/ */
obuf[0] = PPP_ADDRESS(ibuf); /* +1 */ ibuf += MPPE_OVHD;
obuf[1] = PPP_CONTROL(ibuf); /* +1 */ isize -= MPPE_OVHD;
obuf += 2;
ibuf += PPP_HDRLEN + MPPE_OVHD;
isize -= PPP_HDRLEN + MPPE_OVHD; /* -6 */
/* net osize: isize-4 */
/* /*
* Decrypt the first byte in order to check if it is * Decrypt the first byte in order to check if it is