Rewrite, fix and improve str2net().
This is a complete rewrite of the str2net() function. Besides refactoring duplicate code, this new code brings the following fixes and improvements: - Fixes handling of leading/trailing double colon in IPv6 addresses. For example, with the previous code the address 2001:0db8:85a3:0000:0000:8a2e:0370:: is interpreted as a MAC address, and ::0db8:85a3:0000:0000:8a2e:0370:7334 is rejected. - Catches more invalid cases, such as garbage at the end of the string. - Adds support for dotted quad notation in IPv6 (e.g. ::1.2.3.4). See RFC 4291, section 2.2 for details on the textual format of IPv6 addresses.
This commit is contained in:
Etienne Dechamps
parent
e024b7a2c5
commit
3d730a40a4
1 changed files with 88 additions and 119 deletions
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@ -181,150 +181,119 @@ int subnet_compare(const subnet_t *a, const subnet_t *b) {
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/* Ascii representation of subnets */
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bool str2net(subnet_t *subnet, const char *subnetstr) {
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int i, l;
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uint16_t x[8];
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char str[1024];
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strncpy(str, subnetstr, sizeof(str));
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int consumed;
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int weight = 10;
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char *weight_separator = strchr(str, '#');
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if (weight_separator) {
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char *weight_str = weight_separator + 1;
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if (sscanf(weight_str, "%d%n", &weight, &consumed) < 1)
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return false;
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if (weight_str[consumed])
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return false;
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*weight_separator = 0;
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}
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if(sscanf(subnetstr, "%hu.%hu.%hu.%hu/%d#%d",
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&x[0], &x[1], &x[2], &x[3], &l, &weight) >= 5) {
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if(l < 0 || l > 32)
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int prefixlength = -1;
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char *prefixlength_separator = strchr(str, '/');
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if (prefixlength_separator) {
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char* prefixlength_str = prefixlength_separator + 1;
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if (sscanf(prefixlength_str, "%d%n", &prefixlength, &consumed) < 1)
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return false;
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if (prefixlength_str[consumed])
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return false;
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*prefixlength_separator = 0;
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if (prefixlength < 0)
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return false;
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}
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uint16_t x[8];
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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]) {
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/*
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Normally we should check that each part has two digits to prevent ambiguities.
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However, in old tinc versions net2str() will agressively return MAC addresses with one-digit parts,
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so we have to accept them otherwise we would be unable to parse ADD_SUBNET messages.
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*/
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if (prefixlength >= 0)
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return false;
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subnet->type = SUBNET_IPV4;
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subnet->net.ipv4.prefixlength = l;
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subnet->weight = weight;
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for(int i = 0; i < 4; i++) {
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if(x[i] > 255)
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return false;
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subnet->net.ipv4.address.x[i] = x[i];
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}
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return true;
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}
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if(sscanf(subnetstr, "%hx:%hx:%hx:%hx:%hx:%hx:%hx:%hx/%d#%d",
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&x[0], &x[1], &x[2], &x[3], &x[4], &x[5], &x[6], &x[7],
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&l, &weight) >= 9) {
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if(l < 0 || l > 128)
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return false;
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subnet->type = SUBNET_IPV6;
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subnet->net.ipv6.prefixlength = l;
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subnet->weight = weight;
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for(i = 0; i < 8; i++)
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subnet->net.ipv6.address.x[i] = htons(x[i]);
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return true;
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}
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if(sscanf(subnetstr, "%hu.%hu.%hu.%hu#%d", &x[0], &x[1], &x[2], &x[3], &weight) >= 4) {
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subnet->type = SUBNET_IPV4;
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subnet->net.ipv4.prefixlength = 32;
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subnet->weight = weight;
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for(i = 0; i < 4; i++) {
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if(x[i] > 255)
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return false;
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subnet->net.ipv4.address.x[i] = x[i];
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}
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return true;
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}
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if(sscanf(subnetstr, "%hx:%hx:%hx:%hx:%hx:%hx:%hx:%hx#%d",
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&x[0], &x[1], &x[2], &x[3], &x[4], &x[5], &x[6], &x[7], &weight) >= 8) {
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subnet->type = SUBNET_IPV6;
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subnet->net.ipv6.prefixlength = 128;
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subnet->weight = weight;
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for(i = 0; i < 8; i++)
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subnet->net.ipv6.address.x[i] = htons(x[i]);
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return true;
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}
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if(sscanf(subnetstr, "%hx:%hx:%hx:%hx:%hx:%hx#%d",
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&x[0], &x[1], &x[2], &x[3], &x[4], &x[5], &weight) >= 6) {
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subnet->type = SUBNET_MAC;
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subnet->weight = weight;
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for(i = 0; i < 6; i++)
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for(int i = 0; i < 6; i++)
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subnet->net.mac.address.x[i] = x[i];
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return true;
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}
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// IPv6 short form
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if(strstr(subnetstr, "::")) {
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const char *p;
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char *q;
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int colons = 0;
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// Count number of colons
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for(p = subnetstr; *p; p++)
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if(*p == ':')
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colons++;
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if(colons > 7)
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if (sscanf(str, "%hu.%hu.%hu.%hu%n", &x[0], &x[1], &x[2], &x[3], &consumed) >= 4 && !str[consumed]) {
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if (prefixlength == -1)
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prefixlength = 32;
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if (prefixlength > 32)
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return false;
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// Scan numbers before the double colon
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p = subnetstr;
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for(i = 0; i < colons; i++) {
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if(*p == ':')
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break;
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x[i] = strtoul(p, &q, 0x10);
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if(!q || p == q || *q != ':')
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subnet->type = SUBNET_IPV4;
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subnet->net.ipv4.prefixlength = prefixlength;
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subnet->weight = weight;
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for(int i = 0; i < 4; i++) {
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if (x[i] > 255)
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return false;
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p = ++q;
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subnet->net.ipv4.address.x[i] = x[i];
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}
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return true;
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}
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p++;
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colons -= i;
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if(!i) {
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p++;
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colons--;
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}
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/* IPv6 */
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if(!*p || *p == '/' || *p == '#')
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colons--;
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// Fill in the blanks
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for(; i < 8 - colons; i++)
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x[i] = 0;
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// Scan the remaining numbers
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for(; i < 8; i++) {
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x[i] = strtoul(p, &q, 0x10);
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if(!q || p == q)
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char* last_colon = strrchr(str, ':');
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if (last_colon && sscanf(last_colon, ":%hu.%hu.%hu.%hu%n", &x[0], &x[1], &x[2], &x[3], &consumed) >= 4 && !last_colon[consumed]) {
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/* Dotted quad suffix notation, convert to standard IPv6 notation */
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for (int i = 0; i < 4; i++)
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if (x[i] > 255)
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return false;
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if(i == 7) {
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p = q;
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break;
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sprintf(last_colon, ":%02hx%02hx:%02hx%02hx", x[0], x[1], x[2], x[3]);
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}
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char* double_colon = strstr(str, "::");
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if (double_colon) {
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/* Figure out how many zero groups we need to expand */
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int zero_group_count = 8;
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for (const char* cur = str; *cur; *cur && cur++)
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if (*cur != ':') {
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zero_group_count--;
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for (; *cur && *cur != ':'; cur++);
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}
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if(*q != ':')
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return false;
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p = ++q;
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}
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if (zero_group_count < 1)
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return false;
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l = 128;
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if(*p == '/')
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sscanf(p, "/%d#%d", &l, &weight);
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else if(*p == '#')
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sscanf(p, "#%d", &weight);
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/* Split the double colon in the middle to make room for zero groups */
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double_colon++;
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memmove(double_colon + (zero_group_count * 2 - 1), double_colon, strlen(double_colon) + 1);
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if(l < 0 || l > 128)
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/* Write zero groups in the resulting gap, overwriting the second colon */
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for (int i = 0; i < zero_group_count; i++)
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memcpy(&double_colon[i * 2], "0:", 2);
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/* Remove any leading or trailing colons */
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if (str[0] == ':')
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memmove(&str[0], &str[1], strlen(&str[1]) + 1);
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if (str[strlen(str) - 1] == ':')
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str[strlen(str) - 1] = 0;
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}
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if (sscanf(str, "%hx:%hx:%hx:%hx:%hx:%hx:%hx:%hx%n",
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&x[0], &x[1], &x[2], &x[3], &x[4], &x[5], &x[6], &x[7], &consumed) >= 8 && !str[consumed]) {
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if (prefixlength == -1)
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prefixlength = 128;
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if (prefixlength > 128)
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return false;
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subnet->type = SUBNET_IPV6;
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subnet->net.ipv6.prefixlength = l;
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subnet->net.ipv6.prefixlength = prefixlength;
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subnet->weight = weight;
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for(i = 0; i < 8; i++)
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for(int i = 0; i < 8; i++)
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subnet->net.ipv6.address.x[i] = htons(x[i]);
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return true;
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}
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