X-Git-Url: https://tinc-vpn.org/git/browse?p=tinc;a=blobdiff_plain;f=src%2Fsubnet_parse.c;h=611d6bd4415a83a2c4e99a921ce6f5c1df46aae8;hp=a3c904f5945ae8ca4693e80ff9bff3de30f74ff3;hb=d4410d0cce40929db9a0ce7042ef962f1867234d;hpb=248d300f1be0d5f2aae39202041699ab2b46c56b

diff --git a/src/subnet_parse.c b/src/subnet_parse.c
index a3c904f5..611d6bd4 100644
--- a/src/subnet_parse.c
+++ b/src/subnet_parse.c
@@ -27,6 +27,9 @@
 #include "utils.h"
 #include "xalloc.h"
 
+/* Changing this default will affect ADD_SUBNET messages - beware of inconsistencies between versions */
+static const int DEFAULT_WEIGHT = 10;
+
 /* Subnet mask handling */
 
 int maskcmp(const void *va, const void *vb, int masklen) {
@@ -104,7 +107,7 @@ static int subnet_compare_mac(const subnet_t *a, const subnet_t *b) {
 
 	if(result)
 		return result;
-	
+
 	result = a->weight - b->weight;
 
 	if(result || !a->owner || !b->owner)
@@ -125,7 +128,7 @@ static int subnet_compare_ipv4(const subnet_t *a, const subnet_t *b) {
 
 	if(result)
 		return result;
-	
+
 	result = a->weight - b->weight;
 
 	if(result || !a->owner || !b->owner)
@@ -141,12 +144,12 @@ static int subnet_compare_ipv6(const subnet_t *a, const subnet_t *b) {
 
 	if(result)
 		return result;
-	
+
 	result = memcmp(&a->net.ipv6.address, &b->net.ipv6.address, sizeof(ipv6_t));
 
 	if(result)
 		return result;
-	
+
 	result = a->weight - b->weight;
 
 	if(result || !a->owner || !b->owner)
@@ -181,150 +184,121 @@ int subnet_compare(const subnet_t *a, const subnet_t *b) {
 /* Ascii representation of subnets */
 
 bool str2net(subnet_t *subnet, const char *subnetstr) {
-	int i, l;
-	uint16_t x[8];
-	int weight = 10;
-
-	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)
+	char str[1024];
+	strncpy(str, subnetstr, sizeof(str));
+	str[sizeof str - 1] = 0;
+	int consumed;
+
+	int weight = DEFAULT_WEIGHT;
+	char *weight_separator = strchr(str, '#');
+	if (weight_separator) {
+		char *weight_str = weight_separator + 1;
+		if (sscanf(weight_str, "%d%n", &weight, &consumed) < 1)
 			return false;
+		if (weight_str[consumed])
+			return false;
+		*weight_separator = 0;
+	}
 
-		subnet->type = SUBNET_IPV4;
-		subnet->net.ipv4.prefixlength = l;
-		subnet->weight = weight;
-
-		for(i = 0; i < 4; i++) {
-			if(x[i] > 255)
-				return false;
-			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;
+		if (prefixlength_str[consumed])
+			return false;
+		*prefixlength_separator = 0;
 
-		return true;
+		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 agressively 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++) {
-			if(x[i] > 255)
+		for(int i = 0; i < 4; i++) {
+			if (x[i] > 255)
 				return false;
 			subnet->net.ipv4.address.x[i] = x[i];
 		}
-
-		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;
-
-		for(i = 0; i < 8; i++)
-			subnet->net.ipv6.address.x[i] = htons(x[i]);
-
 		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;
+	/* IPv6 */
 
-		for(i = 0; i < 6; i++)
-			subnet->net.mac.address.x[i] = x[i];
-
-		return true;
+	char* last_colon = strrchr(str, ':');
+	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]);
 	}
 
-	// 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(colons > 7)
+	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;
 
-		// Scan numbers before the double colon
-		p = subnetstr;
-		for(i = 0; i < colons; i++) {
-			if(*p == ':')
-				break;
-			x[i] = strtoul(p, &q, 0x10);
-			if(!q || p == q || *q != ':')
-				return false;
-			p = ++q;
-		}
+		/* 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);
 
-		p++;
-		colons -= i;
-		if(!i) {
-			p++;
-			colons--;
-		}
-
-		if(!*p || *p == '/' || *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);
 
-		// 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;
-		}
-
-		l = 128;
-		if(*p == '/')
-			sscanf(p, "/%d#%d", &l, &weight);
-		else if(*p == '#')
-			sscanf(p, "#%d", &weight);
+		/* 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(l < 0 || l > 128)
+	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 (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]);
-
 		return true;
 	}
 
@@ -337,46 +311,98 @@ bool net2str(char *netstr, int len, const subnet_t *subnet) {
 		return false;
 	}
 
+	int result;
+	int prefixlength = -1;
 	switch (subnet->type) {
 		case SUBNET_MAC:
-			snprintf(netstr, len, "%hx:%hx:%hx:%hx:%hx:%hx#%d",
+			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],
-					 subnet->weight);
+					 subnet->net.mac.address.x[5]);
+			netstr += result;
+			len -= result;
 			break;
 
 		case SUBNET_IPV4:
-			snprintf(netstr, len, "%hu.%hu.%hu.%hu/%d#%d",
+			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],
-					 subnet->net.ipv4.prefixlength,
-					 subnet->weight);
+					 subnet->net.ipv4.address.x[3]);
+			netstr += result;
+			len -= result;
+			prefixlength = subnet->net.ipv4.prefixlength;
+			if (prefixlength == 32)
+				prefixlength = -1;
 			break;
 
-		case SUBNET_IPV6:
-			snprintf(netstr, len, "%hx:%hx:%hx:%hx:%hx:%hx:%hx:%hx/%d#%d",
-					 ntohs(subnet->net.ipv6.address.x[0]),
-					 ntohs(subnet->net.ipv6.address.x[1]),
-					 ntohs(subnet->net.ipv6.address.x[2]),
-					 ntohs(subnet->net.ipv6.address.x[3]),
-					 ntohs(subnet->net.ipv6.address.x[4]),
-					 ntohs(subnet->net.ipv6.address.x[5]),
-					 ntohs(subnet->net.ipv6.address.x[6]),
-					 ntohs(subnet->net.ipv6.address.x[7]),
-					 subnet->net.ipv6.prefixlength,
-					 subnet->weight);
+		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, "%hx:", ntohs(subnet->net.ipv6.address.x[i]));
+					i++;
+				}
+				netstr += result;
+				len -= result;
+			}
+
+			/* Remove the trailing colon */
+			netstr--;
+			len++;
+			*netstr = 0;
+
+			prefixlength = subnet->net.ipv6.prefixlength;
+			if (prefixlength == 128)
+				prefixlength = -1;
 			break;
+		}
 
 		default:
 			logger(DEBUG_ALWAYS, LOG_ERR, "net2str() was called with unknown subnet type %d, exiting!", subnet->type);
 			exit(1);
 	}
 
+	if (prefixlength >= 0) {
+		result = snprintf(netstr, len, "/%d", prefixlength);
+		netstr += result;
+		len -= result;
+	}
+
+	if (subnet->weight != DEFAULT_WEIGHT)
+		snprintf(netstr, len, "#%d", subnet->weight);
+
 	return true;
 }