Use inet_pton() to parse Subnets.

Nowadays all operating systems tinc runs on should support IPv6, so we
can rely on inet_pton() and inet_ntop() to convert IPv4 and IPv6
addresses. Use this instead of our own parsing code.

diff --git a/src/subnet_parse.c b/src/subnet_parse.c
index 312e310..3273b0b 100644 (file)
--- a/src/subnet_parse.c
+++ b/src/subnet_parse.c
@@ -213,7 +213,7 @@ int subnet_compare(const subnet_t *a, const subnet_t *b) {
 /* Ascii representation of subnets */
 
 bool str2net(subnet_t *subnet, const char *subnetstr) {
-       char str[1024];
+       char str[64];
        strncpy(str, subnetstr, sizeof(str));
        str[sizeof(str) - 1] = 0;
        int consumed;
@@ -278,7 +278,7 @@ bool str2net(subnet_t *subnet, const char *subnetstr) {
                return true;
        }
 
-       if(sscanf(str, "%hu.%hu.%hu.%hu%n", &x[0], &x[1], &x[2], &x[3], &consumed) >= 4 && !str[consumed]) {
+       if(inet_pton(AF_INET, str, &subnet->net.ipv4.address)) {
                if(prefixlength == -1) {
                        prefixlength = 32;
                }
@@ -291,76 +291,10 @@ bool str2net(subnet_t *subnet, const char *subnetstr) {
                subnet->net.ipv4.prefixlength = prefixlength;
                subnet->weight = weight;
 
-               for(int i = 0; i < 4; i++) {
-                       if(x[i] > 255) {
-                               return false;
-                       }
-
-                       subnet->net.ipv4.address.x[i] = x[i];
-               }
-
                return true;
        }
 
-       /* IPv6 */
-
-       char *last_colon = strrchr(str, ':');
-
-       /* Check that the last colon is not further than possible in an IPv6 address */
-       if(last_colon && last_colon >= str + 5 * 8) {
-               return false;
-       }
-
-       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;
-                       }
-
-               snprintf(last_colon, sizeof(str) - (last_colon - str), ":%02x%02x:%02x%02x", x[0], x[1], x[2], x[3]);
-       }
-
-       char *double_colon = strstr(str, "::");
-
-       if(double_colon) {
-               /* Figure out how many zero groups we need to expand */
-               int zero_group_count = 8;
-
-               for(const char *cur = str; *cur; cur++)
-                       if(*cur != ':') {
-                               zero_group_count--;
-
-                               while(cur[1] && cur[1] != ':') {
-                                       cur++;
-                               }
-                       }
-
-               if(zero_group_count < 1) {
-                       return false;
-               }
-
-               /* 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);
-
-               /* 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);
-               }
-
-               /* Remove any leading or trailing colons */
-               if(str[0] == ':') {
-                       memmove(&str[0], &str[1], strlen(&str[1]) + 1);
-               }
-
-               if(str[strlen(str) - 1] == ':') {
-                       str[strlen(str) - 1] = 0;
-               }
-       }
-
-       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(inet_pton(AF_INET6, str, &subnet->net.ipv6.address)) {
                if(prefixlength == -1) {
                        prefixlength = 128;
                }
@@ -373,10 +307,6 @@ bool str2net(subnet_t *subnet, const char *subnetstr) {
                subnet->net.ipv6.prefixlength = prefixlength;
                subnet->weight = weight;
 
-               for(int i = 0; i < 8; i++) {
-                       subnet->net.ipv6.address.x[i] = htons(x[i]);
-               }
-
                return true;
        }
 
@@ -394,25 +324,17 @@ bool net2str(char *netstr, int len, const subnet_t *subnet) {
 
        switch(subnet->type) {
        case SUBNET_MAC:
-               result = snprintf(netstr, len, "%02x:%02x:%02x:%02x:%02x:%02x",
-                                 subnet->net.mac.address.x[0],
-                                 subnet->net.mac.address.x[1],
-                                 subnet->net.mac.address.x[2],
-                                 subnet->net.mac.address.x[3],
-                                 subnet->net.mac.address.x[4],
-                                 subnet->net.mac.address.x[5]);
-               netstr += result;
-               len -= result;
+               snprintf(netstr, len, "%02x:%02x:%02x:%02x:%02x:%02x",
+                        subnet->net.mac.address.x[0],
+                        subnet->net.mac.address.x[1],
+                        subnet->net.mac.address.x[2],
+                        subnet->net.mac.address.x[3],
+                        subnet->net.mac.address.x[4],
+                        subnet->net.mac.address.x[5]);
                break;
 
        case SUBNET_IPV4:
-               result = snprintf(netstr, len, "%u.%u.%u.%u",
-                                 subnet->net.ipv4.address.x[0],
-                                 subnet->net.ipv4.address.x[1],
-                                 subnet->net.ipv4.address.x[2],
-                                 subnet->net.ipv4.address.x[3]);
-               netstr += result;
-               len -= result;
+               inet_ntop(AF_INET, &subnet->net.ipv4.address, netstr, len);
                prefixlength = subnet->net.ipv4.prefixlength;
 
                if(prefixlength == 32) {
@@ -422,60 +344,7 @@ bool net2str(char *netstr, int len, const subnet_t *subnet) {
                break;
 
        case SUBNET_IPV6: {
-               /* Find the longest sequence of consecutive zeroes */
-               int max_zero_length = 0;
-               int max_zero_length_index = 0;
-               int current_zero_length = 0;
-               int current_zero_length_index = 0;
-
-               for(int i = 0; i < 8; i++) {
-                       if(subnet->net.ipv6.address.x[i] != 0) {
-                               current_zero_length = 0;
-                       } else {
-                               if(current_zero_length == 0) {
-                                       current_zero_length_index = i;
-                               }
-
-                               current_zero_length++;
-
-                               if(current_zero_length > max_zero_length) {
-                                       max_zero_length = current_zero_length;
-                                       max_zero_length_index = current_zero_length_index;
-                               }
-                       }
-               }
-
-               /* Print the address */
-               for(int i = 0; i < 8;) {
-                       if(max_zero_length > 1 && max_zero_length_index == i) {
-                               /* Shorten the representation as per RFC 5952 */
-                               const char *const FORMATS[] = { "%.1s", "%.2s", "%.3s" };
-                               const char *const *format = &FORMATS[0];
-
-                               if(i == 0) {
-                                       format++;
-                               }
-
-                               if(i + max_zero_length == 8) {
-                                       format++;
-                               }
-
-                               result = snprintf(netstr, len, *format, ":::");
-                               i += max_zero_length;
-                       } else {
-                               result = snprintf(netstr, len, "%x:", ntohs(subnet->net.ipv6.address.x[i]));
-                               i++;
-                       }
-
-                       netstr += result;
-                       len -= result;
-               }
-
-               /* Remove the trailing colon */
-               netstr--;
-               len++;
-               *netstr = 0;
-
+               inet_ntop(AF_INET6, &subnet->net.ipv6.address, netstr, len);
                prefixlength = subnet->net.ipv6.prefixlength;
 
                if(prefixlength == 128) {
@@ -490,6 +359,10 @@ bool net2str(char *netstr, int len, const subnet_t *subnet) {
                exit(1);
        }
 
+       size_t used = strlen(netstr);
+       netstr += used;
+       len -= used;
+
        if(prefixlength >= 0) {
                result = snprintf(netstr, len, "/%d", prefixlength);
                netstr += result;