torproject/tor
1
0
Fork 0
mirror of https://gitlab.torproject.org/tpo/core/tor.git synced 2024-12-06 19:41:15 +01:00
Code Issues Actions Packages Projects Releases Wiki Activity

Consdiff: extract router ID hash iteration functions

Browse Source 
There was a frequent block of code that did "find the next router
line, see if we've hit the end of the list, get the ID hash from the
line, and enforce well-ordering."  Per Ahf's review, I'm extracting
it to its own function.
This commit is contained in:
Nick Mathewson
2017-03-16 11:04:58 -04:00
parent 83049cebc0
commit 672e2a5461
1 changed files with 53 additions and 41 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/or/consdiff.c
+53 -41
View File
@@ -492,6 +492,46 @@ base64cmp(const cdline_t *hash1, const cdline_t *hash2)
}
}
/** Structure used to remember the previous and current identity hash of
* the "r " lines in a consensus, to enforce well-ordering. */
typedef struct router_id_iterator_t {
cdline_t last_hash;
cdline_t hash;
} router_id_iterator_t;
/**
* Initializer for a router_id_iterator_t.
*/
#define ROUTER_ID_ITERATOR_INIT { { NULL, 0 }, { NULL, 0 } }
/** Given an index *<b>idxp</b> into the consensus at <b>cons</b>, advance
* the index to the next router line ("r ...") in the consensus, or to
* an index one after the end of the list if there is no such line.
*
* Use <b>iter</b> to record the hash of the found router line, if any,
* and to enforce ordering on the hashes. If the hashes are mis-ordered,
* return -1. Else, return 0.
**/
static int
find_next_router_line(const smartlist_t *cons,
const char *consname,
int *idxp,
router_id_iterator_t *iter)
{
*idxp = next_router(cons, *idxp);
if (*idxp < smartlist_len(cons)) {
memcpy(&iter->last_hash, &iter->hash, sizeof(cdline_t));
if (get_id_hash(smartlist_get(cons, *idxp), &iter->hash) < 0 ||
base64cmp(&iter->hash, &iter->last_hash) <= 0) {
log_warn(LD_CONSDIFF, "Refusing to generate consensus diff because "
"the %s consensus doesn't have its router entries sorted "
"properly.", consname);
return -1;
}
}
return 0;
}
/** Generate an ed diff as a smartlist from two consensuses, also given as
* smartlists. Will return NULL if the diff could not be generated, which can
* happen if any lines the script had to add matched "." or if the routers
@@ -529,8 +569,8 @@ gen_ed_diff(const smartlist_t *cons1, const smartlist_t *cons2,
int start1=0, start2=0;
/* To check that hashes are ordered properly */
cdline_t hash1 = { NULL, 0 }, hash2 = { NULL, 0 };
cdline_t last_hash1 = { NULL, 0 }, last_hash2 = { NULL, 0 };
router_id_iterator_t iter1 = ROUTER_ID_ITERATOR_INIT;
router_id_iterator_t iter2 = ROUTER_ID_ITERATOR_INIT;
/* i1 and i2 are initialized at the first line of each consensus. They never
* reach past len1 and len2 respectively, since next_router doesn't let that
@@ -545,30 +585,14 @@ gen_ed_diff(const smartlist_t *cons1, const smartlist_t *cons2,
* yet at the end.
*/
if (i1 < len1) {
i1 = next_router(cons1, i1);
if (i1 != len1) {
memcpy(&last_hash1, &hash1, sizeof(cdline_t));
if (get_id_hash(smartlist_get(cons1, i1), &hash1) < 0 ||
base64cmp(&hash1, &last_hash1) <= 0) {
log_warn(LD_CONSDIFF, "Refusing to generate consensus diff because "
"the base consensus doesn't have its router entries "
"sorted properly.");
goto error_cleanup;
}
if (find_next_router_line(cons1, "base", &i1, &iter1) < 0) {
goto error_cleanup;
}
}
if (i2 < len2) {
i2 = next_router(cons2, i2);
if (i2 != len2) {
memcpy(&last_hash2, &hash2, sizeof(cdline_t));
if (get_id_hash(smartlist_get(cons2, i2), &hash2) < 0 ||
base64cmp(&hash2, &last_hash2) <= 0) {
log_warn(LD_CONSDIFF, "Refusing to generate consensus diff because "
"the target consensus doesn't have its router entries "
"sorted properly.");
goto error_cleanup;
}
if (find_next_router_line(cons2, "target", &i2, &iter2) < 0) {
goto error_cleanup;
}
}
@@ -587,10 +611,12 @@ gen_ed_diff(const smartlist_t *cons1, const smartlist_t *cons2,
* consensus has already reached the end, both are extended to their
* respecting ends since we are done.
*/
int cmp = base64cmp(&hash1, &hash2);
int cmp = base64cmp(&iter1.hash, &iter2.hash);
while (cmp != 0) {
if (i1 < len1 && cmp < 0) {
i1 = next_router(cons1, i1);
if (find_next_router_line(cons1, "base", &i1, &iter1) < 0) {
goto error_cleanup;
}
if (i1 == len1) {
/* We finished the first consensus, so grab all the remaining
* lines of the second consensus and finish up.
@@ -598,16 +624,10 @@ gen_ed_diff(const smartlist_t *cons1, const smartlist_t *cons2,
i2 = len2;
break;
}
memcpy(&last_hash1, &hash1, sizeof(cdline_t));
if (get_id_hash(smartlist_get(cons1, i1), &hash1) < 0 ||
base64cmp(&hash1, &last_hash1) <= 0) {
log_warn(LD_CONSDIFF, "Refusing to generate consensus diff "
"because the base consensus doesn't have its router entries "
"sorted properly.");
} else if (i2 < len2 && cmp > 0) {
if (find_next_router_line(cons2, "target", &i2, &iter2) < 0) {
goto error_cleanup;
}
} else if (i2 < len2 && cmp > 0) {
i2 = next_router(cons2, i2);
if (i2 == len2) {
/* We finished the second consensus, so grab all the remaining
* lines of the first consensus and finish up.
@@ -615,20 +635,12 @@ gen_ed_diff(const smartlist_t *cons1, const smartlist_t *cons2,
i1 = len1;
break;
}
memcpy(&last_hash2, &hash2, sizeof(cdline_t));
if (get_id_hash(smartlist_get(cons2, i2), &hash2) < 0 ||
base64cmp(&hash2, &last_hash2) <= 0) {
log_warn(LD_CONSDIFF, "Refusing to generate consensus diff "
"because the target consensus doesn't have its router entries "
"sorted properly.");
goto error_cleanup;
}
} else {
i1 = len1;
i2 = len2;
break;
}
cmp = base64cmp(&hash1, &hash2);
cmp = base64cmp(&iter1.hash, &iter2.hash);
}
}