diff --git a/changes/bug19011 b/changes/bug19011 new file mode 100644 index 0000000000..de178fd438 --- /dev/null +++ b/changes/bug19011 @@ -0,0 +1,7 @@ + o Minor bugfixes (directory authorities, voting): + - Add a new consensus method (31) to support any future changes that + authorities decide to make to the value of bwweightscale or + maxunmeasuredbw. Previously, there was a bug that prevented the + authorities from parsing these consensus parameters correctly under + most circumstances. + Fixes bug 19011; bugfix on 0.2.2.10-alpha. diff --git a/src/feature/dirauth/dirvote.c b/src/feature/dirauth/dirvote.c index a1f9bb28ae..4f494a75a3 100644 --- a/src/feature/dirauth/dirvote.c +++ b/src/feature/dirauth/dirvote.c @@ -1757,26 +1757,14 @@ networkstatus_compute_consensus(smartlist_t *votes, } { - char *max_unmeasured_param = NULL; - /* XXXX Extract this code into a common function. Or don't! see #19011 */ - if (params) { - if (strcmpstart(params, "maxunmeasuredbw=") == 0) - max_unmeasured_param = params; - else - max_unmeasured_param = strstr(params, " maxunmeasuredbw="); - } - if (max_unmeasured_param) { - int ok = 0; - char *eq = strchr(max_unmeasured_param, '='); - if (eq) { - max_unmeasured_bw_kb = (uint32_t) - tor_parse_ulong(eq+1, 10, 1, UINT32_MAX, &ok, NULL); - if (!ok) { - log_warn(LD_DIR, "Bad element '%s' in max unmeasured bw param", - escaped(max_unmeasured_param)); - max_unmeasured_bw_kb = DEFAULT_MAX_UNMEASURED_BW_KB; - } - } + if (consensus_method < MIN_METHOD_FOR_CORRECT_BWWEIGHTSCALE) { + max_unmeasured_bw_kb = (int32_t) extract_param_buggy( + params, "maxunmeasuredbw", DEFAULT_MAX_UNMEASURED_BW_KB); + } else { + max_unmeasured_bw_kb = dirvote_get_intermediate_param_value( + param_list, "maxunmeasurdbw", DEFAULT_MAX_UNMEASURED_BW_KB); + if (max_unmeasured_bw_kb < 1) + max_unmeasured_bw_kb = 1; } } @@ -2326,38 +2314,16 @@ networkstatus_compute_consensus(smartlist_t *votes, smartlist_add_strdup(chunks, "directory-footer\n"); { - int64_t weight_scale = BW_WEIGHT_SCALE; - char *bw_weight_param = NULL; - - // Parse params, extract BW_WEIGHT_SCALE if present - // DO NOT use consensus_param_bw_weight_scale() in this code! - // The consensus is not formed yet! - /* XXXX Extract this code into a common function. Or not: #19011. */ - if (params) { - if (strcmpstart(params, "bwweightscale=") == 0) - bw_weight_param = params; - else - bw_weight_param = strstr(params, " bwweightscale="); + int64_t weight_scale; + if (consensus_method < MIN_METHOD_FOR_CORRECT_BWWEIGHTSCALE) { + weight_scale = extract_param_buggy(params, "bwweightscale", + BW_WEIGHT_SCALE); + } else { + weight_scale = dirvote_get_intermediate_param_value( + param_list, "bwweightscale", BW_WEIGHT_SCALE); + if (weight_scale < 1) + weight_scale = 1; } - - if (bw_weight_param) { - int ok=0; - char *eq = strchr(bw_weight_param, '='); - if (eq) { - weight_scale = tor_parse_long(eq+1, 10, 1, INT32_MAX, &ok, - NULL); - if (!ok) { - log_warn(LD_DIR, "Bad element '%s' in bw weight param", - escaped(bw_weight_param)); - weight_scale = BW_WEIGHT_SCALE; - } - } else { - log_warn(LD_DIR, "Bad element '%s' in bw weight param", - escaped(bw_weight_param)); - weight_scale = BW_WEIGHT_SCALE; - } - } - added_weights = networkstatus_compute_bw_weights_v10(chunks, G, M, E, D, T, weight_scale); } @@ -2459,6 +2425,53 @@ networkstatus_compute_consensus(smartlist_t *votes, return result; } +/** Extract the value of a parameter from a string encoding a list of + * parameters, badly. + * + * This is a deliberately buggy implementation, for backward compatibility + * with versions of Tor affected by #19011. Once all authorities have + * upgraded to consensus method 31 or later, then we can throw away this + * function. */ +STATIC int64_t +extract_param_buggy(const char *params, + const char *param_name, + int64_t default_value) +{ + int64_t value = default_value; + const char *param_str = NULL; + + if (params) { + char *prefix1 = NULL, *prefix2=NULL; + tor_asprintf(&prefix1, "%s=", param_name); + tor_asprintf(&prefix2, " %s=", param_name); + if (strcmpstart(params, prefix1) == 0) + param_str = params; + else + param_str = strstr(params, prefix2); + tor_free(prefix1); + tor_free(prefix2); + } + + if (param_str) { + int ok=0; + char *eq = strchr(param_str, '='); + if (eq) { + value = tor_parse_long(eq+1, 10, 1, INT32_MAX, &ok, NULL); + if (!ok) { + log_warn(LD_DIR, "Bad element '%s' in %s", + escaped(param_str), param_name); + value = default_value; + } + } else { + log_warn(LD_DIR, "Bad element '%s' in %s", + escaped(param_str), param_name); + value = default_value; + } + } + + return value; +} + /** Given a list of networkstatus_t for each vote, return a newly allocated * string containing the "package" lines for the vote. */ STATIC char * diff --git a/src/feature/dirauth/dirvote.h b/src/feature/dirauth/dirvote.h index 4f48e45dc3..7d30a51d08 100644 --- a/src/feature/dirauth/dirvote.h +++ b/src/feature/dirauth/dirvote.h @@ -53,7 +53,7 @@ #define MIN_SUPPORTED_CONSENSUS_METHOD 28 /** The highest consensus method that we currently support. */ -#define MAX_SUPPORTED_CONSENSUS_METHOD 30 +#define MAX_SUPPORTED_CONSENSUS_METHOD 31 /** * Lowest consensus method where microdescriptor lines are put in canonical @@ -65,6 +65,11 @@ * See #7869 */ #define MIN_METHOD_FOR_UNPADDED_NTOR_KEY 30 +/** Lowest consensus method for which we use the correct algorithm for + * extracting the bwweightscale= and maxunmeasuredbw= parameters. See #19011. + */ +#define MIN_METHOD_FOR_CORRECT_BWWEIGHTSCALE 31 + /** Default bandwidth to clip unmeasured bandwidths to using method >= * MIN_METHOD_TO_CLIP_UNMEASURED_BW. (This is not a consensus method; do not * get confused with the above macros.) */ @@ -256,6 +261,9 @@ STATIC char *networkstatus_get_detached_signatures(smartlist_t *consensuses); STATIC microdesc_t *dirvote_create_microdescriptor(const routerinfo_t *ri, int consensus_method); +STATIC int64_t extract_param_buggy(const char *params, + const char *param_name, + int64_t default_value); /** The recommended relay protocols for this authority's votes. * Recommending a new protocol causes old tor versions to log a warning. diff --git a/src/test/test_dirvote.c b/src/test/test_dirvote.c index b5e57ad071..d92d1aaf90 100644 --- a/src/test/test_dirvote.c +++ b/src/test/test_dirvote.c @@ -656,6 +656,30 @@ done: ROUTER_FREE(pppp); } +static void +test_dirvote_parse_param_buggy(void *arg) +{ + (void)arg; + + /* Tests for behavior with bug emulation to migrate away from bug 19011. */ + tt_i64_op(extract_param_buggy("blah blah", "bwweightscale", 10000), + OP_EQ, 10000); + tt_i64_op(extract_param_buggy("bwweightscale=7", "bwweightscale", 10000), + OP_EQ, 7); + tt_i64_op(extract_param_buggy("bwweightscale=7 foo=9", + "bwweightscale", 10000), + OP_EQ, 10000); + tt_i64_op(extract_param_buggy("foo=7 bwweightscale=777 bar=9", + "bwweightscale", 10000), + OP_EQ, 10000); + tt_i64_op(extract_param_buggy("foo=7 bwweightscale=1234", + "bwweightscale", 10000), + OP_EQ, 1234); + + done: + ; +} + #define NODE(name, flags) \ { \ #name, test_dirvote_##name, (flags), NULL, NULL \ @@ -668,4 +692,5 @@ struct testcase_t dirvote_tests[] = { NODE(get_sybil_by_ip_version_ipv4, TT_FORK), NODE(get_sybil_by_ip_version_ipv6, TT_FORK), NODE(get_all_possible_sybil, TT_FORK), + NODE(parse_param_buggy, 0), END_OF_TESTCASES};