/*
* This appends a tagged, valid, fully-saturated Bloom filter, useful for
* excluding everything between two 'fenceposts' in an Exclude construct.
*/
static void
append_bf_all(struct ccn_charbuf *c)
{
unsigned char bf_all[9] = { 3, 1, 'A', 0, 0, 0, 0, 0, 0xFF };
const struct ccn_bloom_wire *b = ccn_bloom_validate_wire(bf_all, sizeof(bf_all));
if (b == NULL) abort();
ccnb_append_tagged_blob(c, CCN_DTAG_Bloom, bf_all, sizeof(bf_all));
}
/*
* This appends a tagged, valid, fully-saturated Bloom filter, useful for
* excluding everything between two 'fenceposts' in an Exclude construct.
*/
static void
append_bf_all(struct ccn_charbuf *c)
{
unsigned char bf_all[9] = { 3, 1, 'A', 0, 0, 0, 0, 0, 0xFF };
const struct ccn_bloom_wire *b = ccn_bloom_validate_wire(bf_all, sizeof(bf_all));
if (b == NULL) abort();
ccn_charbuf_append_tt(c, CCN_DTAG_Bloom, CCN_DTAG);
ccn_charbuf_append_tt(c, sizeof(bf_all), CCN_BLOB);
ccn_charbuf_append(c, bf_all, sizeof(bf_all));
ccn_charbuf_append_closer(c);
}
/**
* Test for a match between a ContentObject and an Interest
*
* @param content_object ccnb-encoded ContentObject
* @param content_object_size its size in bytes
* @param implicit_content_digest boolean indicating whether the
* final name component is implicit (as in
* the on-wire format) or explicit (as within
* ccnd's content store).
* @param pc Valid parse information may be provided to
* speed things up. If NULL it will be
* reconstructed internally.
* @param interest_msg ccnb-encoded Interest
* @param interest_msg_size its size in bytes
* @param pi see _pc_
*
* @result 1 if the ccnb-encoded content_object matches the
* ccnb-encoded interest_msg, otherwise 0.
*/
int
ccn_content_matches_interest(const unsigned char *content_object,
size_t content_object_size,
int implicit_content_digest,
struct ccn_parsed_ContentObject *pc,
const unsigned char *interest_msg,
size_t interest_msg_size,
const struct ccn_parsed_interest *pi)
{
struct ccn_parsed_ContentObject pc_store;
struct ccn_parsed_interest pi_store;
int res;
int ncomps;
int prefixstart;
int prefixbytes;
int namecompstart;
int namecompbytes;
int checkdigest = 0;
struct ccn_buf_decoder decoder;
struct ccn_buf_decoder *d;
const unsigned char *nextcomp;
size_t nextcomp_size = 0;
const unsigned char *comp;
size_t comp_size = 0;
const unsigned char *bloom;
size_t bloom_size = 0;
unsigned char match_any[2] = "-";
if (pc == NULL) {
res = ccn_parse_ContentObject(content_object, content_object_size,
&pc_store, NULL);
if (res < 0) return(0);
pc = &pc_store;
}
if (pi == NULL) {
res = ccn_parse_interest(interest_msg, interest_msg_size,
&pi_store, NULL);
if (res < 0) return(0);
pi = &pi_store;
}
if (!ccn_pubid_matches(content_object, pc, interest_msg, pi))
return(0);
ncomps = pc->name_ncomps + (implicit_content_digest ? 1 : 0);
if (ncomps < pi->prefix_comps + pi->min_suffix_comps)
return(0);
if (ncomps > pi->prefix_comps + pi->max_suffix_comps)
return(0);
prefixstart = pi->offset[CCN_PI_B_Component0];
prefixbytes = pi->offset[CCN_PI_E_LastPrefixComponent] - prefixstart;
namecompstart = pc->offset[CCN_PCO_B_Component0];
namecompbytes = pc->offset[CCN_PCO_E_ComponentLast] - namecompstart;
if (prefixbytes > namecompbytes) {
/*
* The only way for this to be a match is if the implicit
* content digest name component comes into play.
*/
if (implicit_content_digest &&
pi->offset[CCN_PI_B_LastPrefixComponent] - prefixstart == namecompbytes &&
(pi->offset[CCN_PI_E_LastPrefixComponent] -
pi->offset[CCN_PI_B_LastPrefixComponent]) == 1 + 2 + 32 + 1) {
prefixbytes = namecompbytes;
checkdigest = 1;
}
else
return(0);
}
if (0 != memcmp(interest_msg + prefixstart,
content_object + namecompstart,
prefixbytes))
return(0);
if (checkdigest) {
/*
* The Exclude by next component is not relevant in this case,
* since there is no next component present.
*/
ccn_digest_ContentObject(content_object, pc);
d = ccn_buf_decoder_start(&decoder,
interest_msg + pi->offset[CCN_PI_B_LastPrefixComponent],
(pi->offset[CCN_PI_E_LastPrefixComponent] -
pi->offset[CCN_PI_B_LastPrefixComponent]));
comp_size = 0;
if (ccn_buf_match_dtag(d, CCN_DTAG_Component)) {
ccn_buf_advance(d);
ccn_buf_match_blob(d, &comp, &comp_size);
}
if (comp_size != pc->digest_bytes) abort();
if (0 != memcmp(comp, pc->digest, comp_size))
return(0);
}
else if (pi->offset[CCN_PI_E_Exclude] > pi->offset[CCN_PI_B_Exclude]) {
if (prefixbytes < namecompbytes) {
/* pick out the next component in the content object name */
d = ccn_buf_decoder_start(&decoder,
content_object +
(namecompstart + prefixbytes),
pc->offset[CCN_PCO_E_ComponentLast] -
(namecompstart + prefixbytes));
if (ccn_buf_match_dtag(d, CCN_DTAG_Component)) {
ccn_buf_advance(d);
ccn_buf_match_blob(d, &nextcomp, &nextcomp_size);
}
else
return(0);
}
else if (!implicit_content_digest)
goto exclude_checked;
else if (prefixbytes == namecompbytes) {
/* use the digest name as the next component */
ccn_digest_ContentObject(content_object, pc);
nextcomp_size = pc->digest_bytes;
nextcomp = pc->digest;
}
else abort(); /* bug - should have returned already */
d = ccn_buf_decoder_start(&decoder,
interest_msg + pi->offset[CCN_PI_B_Exclude],
pi->offset[CCN_PI_E_Exclude] -
pi->offset[CCN_PI_B_Exclude]);
if (!ccn_buf_match_dtag(d, CCN_DTAG_Exclude))
abort();
ccn_buf_advance(d);
bloom = NULL;
bloom_size = 0;
if (ccn_buf_match_dtag(d, CCN_DTAG_Any)) {
ccn_buf_advance(d);
bloom = match_any;
ccn_buf_check_close(d);
}
else if (ccn_buf_match_dtag(d, CCN_DTAG_Bloom)) {
ccn_buf_advance(d);
if (ccn_buf_match_blob(d, &bloom, &bloom_size))
ccn_buf_advance(d);
ccn_buf_check_close(d);
}
while (ccn_buf_match_dtag(d, CCN_DTAG_Component)) {
ccn_buf_advance(d);
comp_size = 0;
if (ccn_buf_match_blob(d, &comp, &comp_size))
ccn_buf_advance(d);
ccn_buf_check_close(d);
if (comp_size > nextcomp_size)
break;
if (comp_size == nextcomp_size) {
res = memcmp(comp, nextcomp, comp_size);
if (res == 0)
return(0); /* One of the explicit excludes */
if (res > 0)
break;
}
bloom = NULL;
bloom_size = 0;
if (ccn_buf_match_dtag(d, CCN_DTAG_Any)) {
ccn_buf_advance(d);
bloom = match_any;
ccn_buf_check_close(d);
}
else if (ccn_buf_match_dtag(d, CCN_DTAG_Bloom)) {
ccn_buf_advance(d);
if (ccn_buf_match_blob(d, &bloom, &bloom_size))
ccn_buf_advance(d);
ccn_buf_check_close(d);
}
}
/*
* Now we have isolated the applicable filter (Any or Bloom or none).
*/
if (bloom == match_any)
return(0);
else if (bloom_size != 0) {
const struct ccn_bloom_wire *f = ccn_bloom_validate_wire(bloom, bloom_size);
/* If not a valid filter, treat like a false positive */
if (f == NULL)
return(0);
if (ccn_bloom_match_wire(f, nextcomp, nextcomp_size))
return(0);
}
exclude_checked: {}
}
/*
* At this point the prefix matches and exclude-by-next-component is done.
*/
// test any other qualifiers here
return(1);
}