[tor-commits] [tor/master] bug#22143/prop#140: Use <n>, $d commands in diffs to remove signatures
nickm at torproject.org
nickm at torproject.org
Thu May 4 12:37:10 UTC 2017
commit c8baa9b78362e372cfb5e2d3fcc6100d20d00229
Author: Nick Mathewson <nickm at torproject.org>
Date: Wed May 3 12:34:30 2017 -0400
bug#22143/prop#140: Use <n>,$d commands in diffs to remove signatures
In this patch I add support for "delete through end of file" in our
ed diff handler, and generate our diffs so that they remove
everything after in the consensus after the signatures begin.
---
src/or/consdiff.c | 91 ++++++++++++++++++++++++++++++++++++++++++++----
src/test/test_consdiff.c | 18 ++++++----
2 files changed, 96 insertions(+), 13 deletions(-)
diff --git a/src/or/consdiff.c b/src/or/consdiff.c
index e4f7872..3c2140b 100644
--- a/src/or/consdiff.c
+++ b/src/or/consdiff.c
@@ -65,17 +65,35 @@ line_str_eq(const cdline_t *a, const char *b)
return lines_eq(a, &bline);
}
-/** Add a cdline_t to <b>lst</b> holding as its contents the nul-terminated
- * string s. Use the provided memory area for storage. */
-STATIC void
-smartlist_add_linecpy(smartlist_t *lst, memarea_t *area, const char *s)
+/** Return true iff a begins with the same contents as the nul-terminated
+ * string b. */
+static int
+line_starts_with_str(const cdline_t *a, const char *b)
+{
+ const size_t len = strlen(b);
+ tor_assert(len <= UINT32_MAX);
+ return a->len >= len && fast_memeq(a->s, b, len);
+}
+
+/** Return a new cdline_t holding as its contents the nul-terminated
+ * string s. Use the provided memory area for storage. */
+static cdline_t *
+cdline_linecpy(memarea_t *area, const char *s)
{
size_t len = strlen(s);
const char *ss = memarea_memdup(area, s, len);
cdline_t *line = memarea_alloc(area, sizeof(cdline_t));
line->s = ss;
line->len = (uint32_t)len;
- smartlist_add(lst, line);
+ return line;
+}
+
+/** Add a cdline_t to <b>lst</b> holding as its contents the nul-terminated
+ * string s. Use the provided memory area for storage. */
+STATIC void
+smartlist_add_linecpy(smartlist_t *lst, memarea_t *area, const char *s)
+{
+ smartlist_add(lst, cdline_linecpy(area, s));
}
/** Compute the digest of <b>cons</b>, and store the result in
@@ -545,6 +563,42 @@ find_next_router_line(const smartlist_t *cons,
return 0;
}
+/** Line-prefix indicating the beginning of the signatures section that we
+ * intend to delete. */
+#define START_OF_SIGNATURES_SECTION "directory-signature "
+
+/** Pre-process a consensus in <b>cons</b> (represented as a list of cdline_t)
+ * to remove the signatures from it. If the footer is removed, return a
+ * cdline_t containing a delete command to delete the footer, allocated in
+ * <b>area</>. If no footer is removed, return NULL.
+ *
+ * We remove the signatures here because they are not themselves signed, and
+ * as such there might be different encodings for them.
+ */
+static cdline_t *
+preprocess_consensus(memarea_t *area,
+ smartlist_t *cons)
+{
+ int idx;
+ int dirsig_idx = -1;
+ for (idx = 0; idx < smartlist_len(cons); ++idx) {
+ cdline_t *line = smartlist_get(cons, idx);
+ if (line_starts_with_str(line, START_OF_SIGNATURES_SECTION)) {
+ dirsig_idx = idx;
+ break;
+ }
+ }
+ if (dirsig_idx >= 0) {
+ char buf[64];
+ while (smartlist_len(cons) > dirsig_idx)
+ smartlist_del(cons, dirsig_idx);
+ tor_snprintf(buf, sizeof(buf), "%d,$d", dirsig_idx+1);
+ return cdline_linecpy(area, buf);
+ } else {
+ return NULL;
+ }
+}
+
/** Generate an ed diff as a smartlist from two consensuses, also given as
* smartlists. Will return NULL if the diff could not be generated, which can
* happen if any lines the script had to add matched "." or if the routers
@@ -566,13 +620,22 @@ find_next_router_line(const smartlist_t *cons,
* calc_changes(cons1_sl, cons2_sl, changed1, changed2);
*/
STATIC smartlist_t *
-gen_ed_diff(const smartlist_t *cons1, const smartlist_t *cons2,
+gen_ed_diff(const smartlist_t *cons1_orig, const smartlist_t *cons2,
memarea_t *area)
{
+ smartlist_t *cons1 = smartlist_new();
+ smartlist_add_all(cons1, cons1_orig);
+ cdline_t *remove_trailer = preprocess_consensus(area, cons1);
+
int len1 = smartlist_len(cons1);
int len2 = smartlist_len(cons2);
smartlist_t *result = smartlist_new();
+ if (remove_trailer) {
+ /* There's a delete-the-trailer line at the end, so add it here. */
+ smartlist_add(result, remove_trailer);
+ }
+
/* Initialize the changed bitarrays to zero, so that calc_changes only needs
* to set the ones that matter and leave the rest untouched.
*/
@@ -746,6 +809,7 @@ gen_ed_diff(const smartlist_t *cons1, const smartlist_t *cons2,
}
}
+ smartlist_free(cons1);
bitarray_free(changed1);
bitarray_free(changed2);
@@ -753,6 +817,7 @@ gen_ed_diff(const smartlist_t *cons1, const smartlist_t *cons2,
error_cleanup:
+ smartlist_free(cons1);
bitarray_free(changed1);
bitarray_free(changed2);
@@ -811,6 +876,7 @@ apply_ed_diff(const smartlist_t *cons1, const smartlist_t *diff,
const char *ptr = diff_line;
int start = 0, end = 0;
int had_range = 0;
+ int end_was_eof = 0;
if (get_linenum(&ptr, &start) < 0) {
log_warn(LD_CONSDIFF, "Could not apply consensus diff because "
"an ed command was missing a line number.");
@@ -820,7 +886,11 @@ apply_ed_diff(const smartlist_t *cons1, const smartlist_t *diff,
/* Two-item range */
had_range = 1;
++ptr;
- if (get_linenum(&ptr, &end) < 0) {
+ if (*ptr == '$') {
+ end_was_eof = 1;
+ end = smartlist_len(cons1);
+ ++ptr;
+ } else if (get_linenum(&ptr, &end) < 0) {
log_warn(LD_CONSDIFF, "Could not apply consensus diff because "
"an ed command was missing a range end line number.");
goto error_cleanup;
@@ -867,6 +937,13 @@ apply_ed_diff(const smartlist_t *cons1, const smartlist_t *diff,
goto error_cleanup;
}
+ /** $ is not allowed with non-d actions. */
+ if (end_was_eof && action != 'd') {
+ log_warn(LD_CONSDIFF, "Could not apply consensus diff because "
+ "it wanted to use $ with a command other than delete");
+ goto error_cleanup;
+ }
+
/* 'a' commands are not allowed to have ranges. */
if (had_range && action == 'a') {
log_warn(LD_CONSDIFF, "Could not apply consensus diff because "
diff --git a/src/test/test_consdiff.c b/src/test/test_consdiff.c
index 2e78672..cdc1e6d 100644
--- a/src/test/test_consdiff.c
+++ b/src/test/test_consdiff.c
@@ -931,18 +931,24 @@ test_consdiff_gen_diff(void *arg)
consensus_split_lines(cons1, cons1_str, area);
diff = consdiff_gen_diff(cons1, cons2, &digests1, &digests2, area);
tt_ptr_op(NULL, OP_NE, diff);
- tt_int_op(7, OP_EQ, smartlist_len(diff));
+ tt_int_op(11, OP_EQ, smartlist_len(diff));
tt_assert(line_str_eq(smartlist_get(diff, 0),
"network-status-diff-version 1"));
tt_assert(line_str_eq(smartlist_get(diff, 1), "hash "
"95D70F5A3CC65F920AA8B44C4563D7781A082674329661884E19E94B79D539C2 "
"7AFECEFA4599BA33D603653E3D2368F648DF4AC4723929B0F7CF39281596B0C1"));
- tt_assert(line_str_eq(smartlist_get(diff, 2), "3,4d"));
- tt_assert(line_str_eq(smartlist_get(diff, 3), "1a"));
- tt_assert(line_str_eq(smartlist_get(diff, 4),
+ tt_assert(line_str_eq(smartlist_get(diff, 2), "6,$d"));
+ tt_assert(line_str_eq(smartlist_get(diff, 3), "3,4c"));
+ tt_assert(line_str_eq(smartlist_get(diff, 4), "bar"));
+ tt_assert(line_str_eq(smartlist_get(diff, 5),
+ "directory-signature foo bar"));
+ tt_assert(line_str_eq(smartlist_get(diff, 6),
+ "."));
+ tt_assert(line_str_eq(smartlist_get(diff, 7), "1a"));
+ tt_assert(line_str_eq(smartlist_get(diff, 8),
"r name aaaaaaaaaaaaaaaaa etc"));
- tt_assert(line_str_eq(smartlist_get(diff, 5), "foo"));
- tt_assert(line_str_eq(smartlist_get(diff, 6), "."));
+ tt_assert(line_str_eq(smartlist_get(diff, 9), "foo"));
+ tt_assert(line_str_eq(smartlist_get(diff, 10), "."));
/* TODO: small real use-cases, i.e. consensuses. */
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