From: Guus Sliepen Date: Thu, 11 Apr 2019 19:01:36 +0000 (+0200) Subject: Backport tinc 1.1's str2net() function. X-Git-Tag: release-1.0.36~5 X-Git-Url: https://git.tinc-vpn.org/git/browse?a=commitdiff_plain;h=5b931cc42dedaa72604a836d8a765e8f00656303;p=tinc Backport tinc 1.1's str2net() function. The old function could get confused by short-hand IPv6 notation (using ::) and mistake them for MAC addresses. The new code is more strict; it will correctly handle all short-hand addresses, and will return an error when an address has trailing garbage instead of ignoring it. --- diff --git a/src/subnet.c b/src/subnet.c index dc30b013..0939d4c1 100644 --- a/src/subnet.c +++ b/src/subnet.c @@ -205,55 +205,85 @@ void subnet_del(node_t *n, subnet_t *subnet) { /* Ascii representation of subnets */ bool str2net(subnet_t *subnet, const char *subnetstr) { - int i, l; - uint16_t x[8]; + char str[1024]; + strncpy(str, subnetstr, sizeof(str)); + str[sizeof(str) - 1] = 0; + int consumed; + int weight = 10; + char *weight_separator = strchr(str, '#'); + + if(weight_separator) { + char *weight_str = weight_separator + 1; - if(sscanf(subnetstr, "%hu.%hu.%hu.%hu/%d#%d", - &x[0], &x[1], &x[2], &x[3], &l, &weight) >= 5) { - if(l < 0 || l > 32) { + if(sscanf(weight_str, "%d%n", &weight, &consumed) < 1) { return false; } - subnet->type = SUBNET_IPV4; - subnet->net.ipv4.prefixlength = l; - subnet->weight = weight; + if(weight_str[consumed]) { + return false; + } - for(i = 0; i < 4; i++) { - if(x[i] > 255) { - return false; - } + *weight_separator = 0; + } - subnet->net.ipv4.address.x[i] = x[i]; + int prefixlength = -1; + char *prefixlength_separator = strchr(str, '/'); + + if(prefixlength_separator) { + char *prefixlength_str = prefixlength_separator + 1; + + if(sscanf(prefixlength_str, "%d%n", &prefixlength, &consumed) < 1) { + return false; } - return true; + if(prefixlength_str[consumed]) { + return false; + } + + *prefixlength_separator = 0; + + if(prefixlength < 0) { + return false; + } } - if(sscanf(subnetstr, "%hx:%hx:%hx:%hx:%hx:%hx:%hx:%hx/%d#%d", - &x[0], &x[1], &x[2], &x[3], &x[4], &x[5], &x[6], &x[7], - &l, &weight) >= 9) { - if(l < 0 || l > 128) { + uint16_t x[8]; + + if(sscanf(str, "%hx:%hx:%hx:%hx:%hx:%hx%n", &x[0], &x[1], &x[2], &x[3], &x[4], &x[5], &consumed) >= 6 && !str[consumed]) { + /* + Normally we should check that each part has two digits to prevent ambiguities. + However, in old tinc versions net2str() will aggressively return MAC addresses with one-digit parts, + so we have to accept them otherwise we would be unable to parse ADD_SUBNET messages. + */ + if(prefixlength >= 0) { return false; } - subnet->type = SUBNET_IPV6; - subnet->net.ipv6.prefixlength = l; + subnet->type = SUBNET_MAC; subnet->weight = weight; - for(i = 0; i < 8; i++) { - subnet->net.ipv6.address.x[i] = htons(x[i]); + for(int i = 0; i < 6; i++) { + subnet->net.mac.address.x[i] = x[i]; } return true; } - if(sscanf(subnetstr, "%hu.%hu.%hu.%hu#%d", &x[0], &x[1], &x[2], &x[3], &weight) >= 4) { + if(sscanf(str, "%hu.%hu.%hu.%hu%n", &x[0], &x[1], &x[2], &x[3], &consumed) >= 4 && !str[consumed]) { + if(prefixlength == -1) { + prefixlength = 32; + } + + if(prefixlength > 32) { + return false; + } + subnet->type = SUBNET_IPV4; - subnet->net.ipv4.prefixlength = 32; + subnet->net.ipv4.prefixlength = prefixlength; subnet->weight = weight; - for(i = 0; i < 4; i++) { + for(int i = 0; i < 4; i++) { if(x[i] > 255) { return false; } @@ -264,118 +294,73 @@ bool str2net(subnet_t *subnet, const char *subnetstr) { return true; } - if(sscanf(subnetstr, "%hx:%hx:%hx:%hx:%hx:%hx:%hx:%hx#%d", - &x[0], &x[1], &x[2], &x[3], &x[4], &x[5], &x[6], &x[7], &weight) >= 8) { - subnet->type = SUBNET_IPV6; - subnet->net.ipv6.prefixlength = 128; - subnet->weight = weight; + /* IPv6 */ - for(i = 0; i < 8; i++) { - subnet->net.ipv6.address.x[i] = htons(x[i]); - } + char *last_colon = strrchr(str, ':'); - return true; - } - - if(sscanf(subnetstr, "%hx:%hx:%hx:%hx:%hx:%hx#%d", - &x[0], &x[1], &x[2], &x[3], &x[4], &x[5], &weight) >= 6) { - subnet->type = SUBNET_MAC; - subnet->weight = weight; - - for(i = 0; i < 6; i++) { - subnet->net.mac.address.x[i] = x[i]; - } - - return true; - } - - // IPv6 short form - if(strstr(subnetstr, "::")) { - const char *p; - char *q; - int colons = 0; - - // Count number of colons - for(p = subnetstr; *p; p++) - if(*p == ':') { - colons++; + if(last_colon && sscanf(last_colon, ":%hu.%hu.%hu.%hu%n", &x[0], &x[1], &x[2], &x[3], &consumed) >= 4 && !last_colon[consumed]) { + /* Dotted quad suffix notation, convert to standard IPv6 notation */ + for(int i = 0; i < 4; i++) + if(x[i] > 255) { + return false; } - if(colons > 7) { - return false; - } + snprintf(last_colon, sizeof(str) - (last_colon - str), ":%02x%02x:%02x%02x", x[0], x[1], x[2], x[3]); + } - // Scan numbers before the double colon - p = subnetstr; + char *double_colon = strstr(str, "::"); - for(i = 0; i < colons; i++) { - if(*p == ':') { - break; - } + if(double_colon) { + /* Figure out how many zero groups we need to expand */ + int zero_group_count = 8; - x[i] = strtoul(p, &q, 0x10); + for(const char *cur = str; *cur; cur++) + if(*cur != ':') { + zero_group_count--; - if(!q || p == q || *q != ':') { - return false; + while(cur[1] && cur[1] != ':') { + cur++; + } } - p = ++q; + if(zero_group_count < 1) { + return false; } - p++; - colons -= i; + /* Split the double colon in the middle to make room for zero groups */ + double_colon++; + memmove(double_colon + (zero_group_count * 2 - 1), double_colon, strlen(double_colon) + 1); - if(!i) { - p++; - colons--; + /* Write zero groups in the resulting gap, overwriting the second colon */ + for(int i = 0; i < zero_group_count; i++) { + memcpy(&double_colon[i * 2], "0:", 2); } - if(!*p || *p == '/' || *p == '#') { - colons--; + /* Remove any leading or trailing colons */ + if(str[0] == ':') { + memmove(&str[0], &str[1], strlen(&str[1]) + 1); } - // Fill in the blanks - for(; i < 8 - colons; i++) { - x[i] = 0; - } - - // Scan the remaining numbers - for(; i < 8; i++) { - x[i] = strtoul(p, &q, 0x10); - - if(!q || p == q) { - return false; - } - - if(i == 7) { - p = q; - break; - } - - if(*q != ':') { - return false; - } - - p = ++q; + if(str[strlen(str) - 1] == ':') { + str[strlen(str) - 1] = 0; } + } - l = 128; - - if(*p == '/') { - sscanf(p, "/%d#%d", &l, &weight); - } else if(*p == '#') { - sscanf(p, "#%d", &weight); + if(sscanf(str, "%hx:%hx:%hx:%hx:%hx:%hx:%hx:%hx%n", + &x[0], &x[1], &x[2], &x[3], &x[4], &x[5], &x[6], &x[7], &consumed) >= 8 && !str[consumed]) { + if(prefixlength == -1) { + prefixlength = 128; } - if(l < 0 || l > 128) { + if(prefixlength > 128) { return false; } subnet->type = SUBNET_IPV6; - subnet->net.ipv6.prefixlength = l; + subnet->net.ipv6.prefixlength = prefixlength; subnet->weight = weight; - for(i = 0; i < 8; i++) { + for(int i = 0; i < 8; i++) { subnet->net.ipv6.address.x[i] = htons(x[i]); }