static inline uint8_t FwdTTL (const EncState* enc, uint8_t ttl)
{
uint8_t new_ttl = GetTTL(enc);
if ( !new_ttl )
new_ttl = ttl;
return new_ttl;
}
static inline uint8_t RevTTL (const EncState* enc, uint8_t ttl)
{
uint8_t new_ttl = GetTTL(enc);
if ( !new_ttl )
new_ttl = ( MAX_TTL - ttl );
if ( new_ttl < MIN_TTL )
new_ttl = MIN_TTL;
return new_ttl;
}
static ENC_STATUS IP4_Encode (EncState* enc, Buffer* in, Buffer* out)
{
int len;
uint32_t start = out->end;
IPHdr* hi = (IPHdr*)enc->p->layers[enc->layer-1].start;
IPHdr* ho = (IPHdr*)(out->base + out->end);
PROTO_ID next = NextEncoder(enc);
UPDATE_BOUND(out, sizeof(*ho));
len = GET_IP_HDR_LEN(hi) - sizeof(*hi);
ho->ip_verhl = 0x45;
ho->ip_off = 0;
ho->ip_id = IpId_Next();
ho->ip_tos = hi->ip_tos;
ho->ip_proto = hi->ip_proto;
if ( FORWARD(enc) )
{
uint8_t ttl = AdjTTL(hi->ip_ttl);
ho->ip_src.s_addr = hi->ip_src.s_addr;
ho->ip_dst.s_addr = hi->ip_dst.s_addr;
if ( enc->p->ssnptr )
ttl = GetTTL(enc);
#ifdef NORMALIZER
if ( ttl < ScMinTTL() && ScNewTTL() )
ttl = ScNewTTL();
#endif
ho->ip_ttl = ttl;
}
else
{
uint8_t ttl = MAX_TTL;
ho->ip_src.s_addr = hi->ip_dst.s_addr;
ho->ip_dst.s_addr = hi->ip_src.s_addr;
if ( enc->p->ssnptr )
ttl = GetTTL(enc);
#ifdef NORMALIZER
if ( ttl < ScMinTTL() && ScNewTTL() )
ttl = ScNewTTL();
#endif
ho->ip_ttl = ttl;
}
enc->ip_hdr = (uint8_t*)hi;
enc->ip_len = IP_HLEN(hi) << 2;
if ( next < PROTO_MAX )
{
int err = encoders[next].fencode(enc, in, out);
if ( err ) return err;
}
if ( enc->proto )
{
ho->ip_proto = enc->proto;
enc->proto = 0;
}
len = out->end - start;
ho->ip_len = htons((u_int16_t)len);
ip_checksum(ho, len);
return ENC_OK;
}
