commit 3dd1f064a7d5708585f88beffaf3897ba6555208 Author: Nick Mathewson <nickm@torproject.org> Date: Fri Dec 14 16:07:10 2018 -0500 Rewrite the core of parse_short_policy() to be faster. The old implementation did some funky out-of-order lexing, and tended to parse every port twice if the %d-%d pattern didn't match. Closes ticket 28853. --- changes/ticket28853 | 3 ++ src/core/or/policies.c | 80 ++++++++++++++++++++++++++------------------------ 2 files changed, 45 insertions(+), 38 deletions(-) diff --git a/changes/ticket28853 b/changes/ticket28853 new file mode 100644 index 000000000..e76f6bd8c --- /dev/null +++ b/changes/ticket28853 @@ -0,0 +1,3 @@ + o Minor features (performance): + - Replace parse_short_policy() with a faster implementation, to improve + microdescriptor parsing time. Closes ticket 28853. diff --git a/src/core/or/policies.c b/src/core/or/policies.c index 123fc8566..bffdb1fdd 100644 --- a/src/core/or/policies.c +++ b/src/core/or/policies.c @@ -2720,7 +2720,7 @@ parse_short_policy(const char *summary) int is_accept; int n_entries; short_policy_entry_t entries[MAX_EXITPOLICY_SUMMARY_LEN]; /* overkill */ - const char *next; + char *next; if (!strcmpstart(summary, "accept ")) { is_accept = 1; @@ -2735,57 +2735,56 @@ parse_short_policy(const char *summary) n_entries = 0; for ( ; *summary; summary = next) { - const char *comma = strchr(summary, ','); - unsigned low, high; - char dummy; - char ent_buf[32]; - size_t len; - - next = comma ? comma+1 : strchr(summary, '\0'); - len = comma ? (size_t)(comma - summary) : strlen(summary); - if (n_entries == MAX_EXITPOLICY_SUMMARY_LEN) { log_fn(LOG_PROTOCOL_WARN, LD_DIR, "Impossibly long policy summary %s", escaped(orig_summary)); return NULL; } - if (! TOR_ISDIGIT(*summary) || len > (sizeof(ent_buf)-1)) { - /* unrecognized entry format. skip it. */ - continue; - } - if (len < 1) { - /* empty; skip it. */ - /* XXX This happens to be unreachable, since if len==0, then *summary is - * ',' or '\0', and the TOR_ISDIGIT test above would have failed. */ - continue; + unsigned low, high; + int ok; + low = (unsigned) tor_parse_ulong(summary, 10, 1, 65535, &ok, &next); + if (!ok) { + if (! TOR_ISDIGIT(*summary) || *summary == ',') { + /* Unrecognized format: skip it. */ + goto skip_ent; + } else { + goto bad_ent; + } } - memcpy(ent_buf, summary, len); - ent_buf[len] = '\0'; + switch (*next) { + case ',': + ++next; + /* fall through */ + case '\0': + high = low; + break; + case '-': + high = (unsigned) tor_parse_ulong(next+1, 10, low, 65535, &ok, &next); + if (!ok) + goto bad_ent; + + if (*next == ',') + ++next; + else if (*next != '\0') + goto bad_ent; - if (tor_sscanf(ent_buf, "%u-%u%c", &low, &high, &dummy) == 2) { - if (low<1 || low>65535 || high<1 || high>65535 || low>high) { - log_fn(LOG_PROTOCOL_WARN, LD_DIR, - "Found bad entry in policy summary %s", escaped(orig_summary)); - return NULL; - } - } else if (tor_sscanf(ent_buf, "%u%c", &low, &dummy) == 1) { - if (low<1 || low>65535) { - log_fn(LOG_PROTOCOL_WARN, LD_DIR, - "Found bad entry in policy summary %s", escaped(orig_summary)); - return NULL; - } - high = low; - } else { - log_fn(LOG_PROTOCOL_WARN, LD_DIR,"Found bad entry in policy summary %s", - escaped(orig_summary)); - return NULL; + break; + default: + goto bad_ent; } entries[n_entries].min_port = low; entries[n_entries].max_port = high; n_entries++; + + continue; + skip_ent: + next = strchr(next, ','); + if (!next) + break; + ++next; } if (n_entries == 0) { @@ -2806,6 +2805,11 @@ parse_short_policy(const char *summary) result->n_entries = n_entries; memcpy(result->entries, entries, sizeof(short_policy_entry_t)*n_entries); return result; + + bad_ent: + log_fn(LOG_PROTOCOL_WARN, LD_DIR,"Found bad entry in policy summary %s", + escaped(orig_summary)); + return NULL; } /** Write <b>policy</b> back out into a string. */