6:05 p.m.
Parses an IP prefix notation string into prefix, start, end, and
netmask. All values are returned in host order.
---
src/util.c | 95 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
src/util.h | 3 ++
2 files changed, 98 insertions(+)
diff --git a/src/util.c b/src/util.c
index 13b01c81..5dc5f15d 100644
--- a/src/util.c
+++ b/src/util.c
@@ -28,6 +28,8 @@
#include <stdio.h>
#include <sys/uio.h>
#include <sys/time.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
#include <ell/ell.h>
@@ -218,3 +220,96 @@ const char *util_get_username(const char *identity)
return identity;
}
+
+static bool is_prefix_valid(uint32_t ip, unsigned int prefix)
+{
+ int i;
+
+ for (i = 31 - prefix; i >= 0; i--) {
+ if (ip & (1 << i))
+ return false;
+ }
+
+ return true;
+}
+
+/*
+ * Parse a prefix notation IP string (e.g. A.B.C.D/E) into an IP range and
+ * netmask. All returned IP addresses/mask will be in host order. The start/end
+ * IP will only include the usable IP range where the last octet is not zero or
+ * 255.
+ */
+bool util_ip_prefix_tohl(const char *ip, uint8_t *prefix_out,
+ uint32_t *start_out, uint32_t *end_out,
+ uint32_t *mask_out)
+{
+ struct in_addr ia;
+ int i;
+ unsigned int prefix;
+ char no_prefix[16];
+ char *endp;
+ uint32_t start_ip;
+ uint32_t end_ip;
+ uint32_t netmask = 0xffffffff;
+ int len = strlen(ip) - 1;
+ bool found = false;
+ uint8_t dots = 0;
+
+ /* Count dots and find prefix offset */
+ for (i = 0; i <= len; i++) {
+ if (ip[i] == '.')
+ dots++;
+ else if (ip[i] == '/') {
+ found = true;
+ break;
+ }
+ }
+
+ if (!found || dots != 3)
+ return false;
+
+ memcpy(no_prefix, ip, i);
+ no_prefix[i] = '\0';
+
+ /* Check if IP preceeding prefix is valid */
+ if (inet_aton(no_prefix, &ia) < 0 || ia.s_addr == 0)
+ return false;
+
+ prefix = strtol(ip + i + 1, &endp, 0);
+ if (*endp != '\0')
+ return false;
+
+ if (prefix < 1 || prefix > 31)
+ return false;
+
+ start_ip = ntohl(ia.s_addr);
+
+ if (!is_prefix_valid(start_ip, prefix))
+ return false;
+
+ /* Usable range is start + 1 .. end - 1 */
+ start_ip += 1;
+
+ /* Calculate end IP and netmask */
+ end_ip = start_ip;
+ for (i = 31 - prefix; i >= 0; i--) {
+ end_ip |= (1 << i);
+ netmask &= ~(1 << i);
+ }
+
+ end_ip -= 1;
+
+ if (prefix_out)
+ *prefix_out = prefix;
+
+ if (start_out)
+ *start_out = start_ip;
+
+ if (end_out)
+ *end_out = end_ip;
+
+ if (mask_out)
+ *mask_out = netmask;
+
+ return true;
+}
diff --git a/src/util.h b/src/util.h
index 2679c117..e6b4747f 100644
--- a/src/util.h
+++ b/src/util.h
@@ -107,4 +107,7 @@ static inline uint32_t util_secure_fill_with_msb(uint32_t val)
return (uint32_t) (val >> (sizeof(val)*8 - 1)) * 0xFFFFFFFF;
}
+bool util_ip_prefix_tohl(const char *ip, uint8_t *prefix, uint32_t *start_out,
+ uint32_t *end_out, uint32_t *mask_out);
+
#endif /* __UTIL_H */
--
2.26.2