utils: add IPv4 string parsing helpers

Define the IPv4 counterparts of u_ip6str() and u_parse_ip6cidr().
Also add the special u_parse_ip4range() which will be useful for
parsing the [client-ip-range] section of accel-ppp.conf.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

accel-pppd/utils.c

@@ -30,6 +30,21 @@ char __export *u_ip6str(const struct in6_addr *addr, char *buf)
 	return buf;
 }
 
+/* Convenient wrapper around inet_ntop() to print IPv4 addresses.
+ * It stores a string representation of addr into buf, which must be at
+ * least INET_ADDRSTRLEN bytes long.
+ *
+ * Returns buf, which is guaranteed to contain a valid string even if an error
+ * occured.
+ */
+char __export *u_ip4str(const struct in_addr *addr, char *buf)
+{
+	if (!inet_ntop(AF_INET, addr, buf, INET_ADDRSTRLEN))
+		snprintf(buf, INET_ADDRSTRLEN, "< ERROR! >");
+
+	return buf;
+}
+
 void __export u_inet_ntoa(in_addr_t addr, char *str)
 {
 	addr = ntohl(addr);
@@ -242,6 +257,70 @@ size_t __export u_parse_ip6cidr(const char *str, struct in6_addr *netp, uint8_t
 	return ptr - str;
 }
 
+/* Parse an IPv4 network prefix in CIDR notation (for example "192.0.2.0/24").
+ * The IP address must be in dotted-decimal format.
+ * Returns the number of bytes parsed, or 0 if str doesn't start with an IPv4
+ * network prefix.
+ */
+size_t __export u_parse_ip4cidr(const char *str, struct in_addr *netp, uint8_t *plen)
+{
+	const char *ptr = str;
+	size_t len;
+
+	len = u_parse_ip4addr(ptr, netp);
+	if (!len)
+		return 0;
+
+	ptr += len;
+	if (*ptr != '/')
+		return 0;
+
+	len = u_parse_u8(++ptr, plen);
+	if (!len)
+		return 0;
+
+	if (*plen > 32)
+		return 0;
+
+	ptr += len;
+
+	return ptr - str;
+}
+
+/* Parse an IPv4 address range (for example "192.0.2.0-255").
+ * The IP address must be in dotted-decimal format. The number following '-'
+ * is the upper bound of the address' least significant byte (the lower bound
+ * is given by the address itself). The upper bound must be bigger or equal
+ * than the lower bound.
+ *
+ * Returns the number of bytes parsed, or 0 if str doesn't start with an IPv4
+ * address range.
+ */
+size_t __export u_parse_ip4range(const char *str, struct in_addr *base_ip, uint8_t *max)
+{
+	const char *ptr = str;
+	size_t len;
+
+	len = u_parse_ip4addr(ptr, base_ip);
+	if (!len)
+		return 0;
+
+	ptr += len;
+	if (*ptr != '-')
+		return 0;
+
+	len = u_parse_u8(++ptr, max);
+	if (!len)
+		return 0;
+
+	if (*max < (ntohl(base_ip->s_addr) & 0xff))
+		return 0;
+
+	ptr += len;
+
+	return ptr - str;
+}
+
 int __export u_randbuf(void *buf, size_t buf_len, int *err)
 {
 	uint8_t *u8buf = buf;

accel-pppd/utils.h

@@ -5,6 +5,7 @@
 #include <stdint.h>
 
 char *u_ip6str(const struct in6_addr *addr, char *buf);
+char *u_ip4str(const struct in_addr *addr, char *buf);
 
 void u_inet_ntoa(in_addr_t, char *str);
 int u_readlong(long int *dst, const char *src, long int min, long int max);
@@ -20,6 +21,8 @@ size_t u_parse_ip6addr(const char *str, struct in6_addr *addr);
 size_t u_parse_ip4addr(const char *str, struct in_addr *addr);
 
 size_t u_parse_ip6cidr(const char *str, struct in6_addr *netp, uint8_t *plen);
+size_t u_parse_ip4cidr(const char *str, struct in_addr *netp, uint8_t *plen);
+size_t u_parse_ip4range(const char *str, struct in_addr *base_ip, uint8_t *max);
 
 int u_randbuf(void *buf, size_t buf_len, int *err);