commit 1be9e84b9c8d104dbdad84dde865e8d2395e67b8 Author: Nick Mathewson nickm@torproject.org Date: Wed Sep 23 12:04:09 2020 -0400

Refactor address comparison in get_sybil_list_by_ip_version --- src/feature/dirauth/dirvote.c | 57 ++++++++++++++++++++++--------------------- 1 file changed, 29 insertions(+), 28 deletions(-)

diff --git a/src/feature/dirauth/dirvote.c b/src/feature/dirauth/dirvote.c index 1b45724c14..b5ad9d99f2 100644 --- a/src/feature/dirauth/dirvote.c +++ b/src/feature/dirauth/dirvote.c @@ -4208,6 +4208,20 @@ MOCK_IMPL(uint32_t,dirserv_get_bandwidth_for_router_kb, return bw_kb; }

+/** + * Helper: compare the address of family `family` in `a` with the address in + * `b`. The family must be one of `AF_INET` and `AF_INET6`. + **/ +static int +compare_routerinfo_addrs_by_family(const routerinfo_t *a, + const routerinfo_t *b, + int family) +{ + const tor_addr_t *addr1 = (family==AF_INET) ? &a->ipv4_addr : &a->ipv6_addr; + const tor_addr_t *addr2 = (family==AF_INET) ? &b->ipv4_addr : &b->ipv6_addr; + return tor_addr_compare(addr1, addr2, CMP_EXACT); +} + /** Helper for sorting: compares two ipv4 routerinfos first by ipv4 address, * and then by descending order of "usefulness" * (see compare_routerinfo_usefulness) @@ -4217,9 +4231,7 @@ compare_routerinfo_by_ipv4(const void **a, const void **b) { const routerinfo_t *first = *(const routerinfo_t **)a; const routerinfo_t *second = *(const routerinfo_t **)b; - const tor_addr_t *first_ipv4 = &first->ipv4_addr; - const tor_addr_t *second_ipv4 = &first->ipv4_addr; - int comparison = tor_addr_compare(first_ipv4, second_ipv4, CMP_EXACT); + int comparison = compare_routerinfo_addrs_by_family(first, second, AF_INET); if (comparison == 0) { // If addresses are equal, use other comparison criteria return compare_routerinfo_usefulness(first, second); @@ -4237,9 +4249,7 @@ compare_routerinfo_by_ipv6(const void **a, const void **b) { const routerinfo_t *first = *(const routerinfo_t **)a; const routerinfo_t *second = *(const routerinfo_t **)b; - const tor_addr_t *first_ipv6 = &(first->ipv6_addr); - const tor_addr_t *second_ipv6 = &(second->ipv6_addr); - int comparison = tor_addr_compare(first_ipv6, second_ipv6, CMP_EXACT); + int comparison = compare_routerinfo_addrs_by_family(first, second, AF_INET6); // If addresses are equal, use other comparison criteria if (comparison == 0) return compare_routerinfo_usefulness(first, second); @@ -4309,10 +4319,8 @@ get_sybil_list_by_ip_version(const smartlist_t *routers, sa_family_t family) const dirauth_options_t *options = dirauth_get_options(); digestmap_t *omit_as_sybil = digestmap_new(); smartlist_t *routers_by_ip = smartlist_new(); - int ipv4_addr_count = 0; - int ipv6_addr_count = 0; - tor_addr_t last_ipv6_addr, last_ipv4_addr; - int addr_comparison = 0; + int addr_count = 0; + routerinfo_t *last_ri = NULL; /* Allow at most this number of Tor servers on a single IP address, ... */ int max_with_same_addr = options->AuthDirMaxServersPerAddr; if (max_with_same_addr <= 0) @@ -4325,24 +4333,17 @@ get_sybil_list_by_ip_version(const smartlist_t *routers, sa_family_t family) smartlist_sort(routers_by_ip, compare_routerinfo_by_ipv4);

SMARTLIST_FOREACH_BEGIN(routers_by_ip, routerinfo_t *, ri) { - if (family == AF_INET6) { - addr_comparison = tor_addr_compare(&last_ipv6_addr, &(ri->ipv6_addr), - CMP_EXACT); - if (addr_comparison != 0) { - tor_addr_copy(&last_ipv6_addr, &(ri->ipv6_addr)); - ipv6_addr_count = 1; - } else if (++ipv6_addr_count > max_with_same_addr) { - digestmap_set(omit_as_sybil, ri->cache_info.identity_digest, ri); - } - } else { - addr_comparison = tor_addr_compare(&last_ipv4_addr, &(ri->ipv4_addr), - CMP_EXACT); - if (addr_comparison != 0) { - tor_addr_copy(&last_ipv4_addr, &(ri->ipv4_addr)); - ipv4_addr_count = 1; - } else if (++ipv4_addr_count > max_with_same_addr) { - digestmap_set(omit_as_sybil, ri->cache_info.identity_digest, ri); - } + bool addrs_equal; + if (last_ri) + addrs_equal = !compare_routerinfo_addrs_by_family(last_ri, ri, family); + else + addrs_equal = false; + + if (! addrs_equal) { + last_ri = ri; + addr_count = 1; + } else if (++addr_count > max_with_same_addr) { + digestmap_set(omit_as_sybil, ri->cache_info.identity_digest, ri); } } SMARTLIST_FOREACH_END(ri); smartlist_free(routers_by_ip);