interfaces-plugin: implement netmask to prefix-length conversion

telekom · Oct 10, 2022 · 752e271 · 752e271
1 parent aea5bc1
commit 752e271
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diff --git a/src/interfaces/src/plugin/data/interfaces/interface/ipv4/address.c b/src/interfaces/src/plugin/data/interfaces/interface/ipv4/address.c
@@ -1,10 +1,14 @@
 #include "address.h"
 #include "plugin/types.h"
 #include "src/utlist.h"
+
+#include <arpa/inet.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
+#include <srpc.h>
+
 interfaces_interface_ipv4_address_element_t* interfaces_interface_ipv4_address_new(void)
 {
     return NULL;
@@ -105,3 +109,30 @@ int interfaces_interface_ipv4_address_element_set_netmask(interfaces_interface_i
 
     return 0;
 }
+
+int interfaces_interface_ipv4_address_netmask2prefix(const char* netmask, uint8_t* prefix_length)
+{
+    int error = 0;
+    struct in_addr addr = { 0 };
+    uint8_t prefix = 0;
+
+    // convert to bits (uint32_t -> addr.s_addr)
+    SRPC_SAFE_CALL_ERR_COND(error, error != 1, inet_pton(AF_INET, netmask, &addr), error_out);
+
+    // count address bits
+    while (addr.s_addr) {
+        if (addr.s_addr & 0x1) {
+            ++prefix;
+        }
+
+        addr.s_addr >>= 1;
+    }
+
+    goto out;
+
+error_out:
+    error = -1;
+
+out:
+    return error;
+}
diff --git a/src/interfaces/src/plugin/data/interfaces/interface/ipv4/address.h b/src/interfaces/src/plugin/data/interfaces/interface/ipv4/address.h
@@ -24,4 +24,10 @@ int interfaces_interface_ipv4_address_element_set_ip(interfaces_interface_ipv4_a
 int interfaces_interface_ipv4_address_element_set_prefix_length(interfaces_interface_ipv4_address_element_t** el, uint8_t prefix_length);
 int interfaces_interface_ipv4_address_element_set_netmask(interfaces_interface_ipv4_address_element_t** el, const char* netmask);
 
+/*
+    Helper functions
+*/
+
+int interfaces_interface_ipv4_address_netmask2prefix(const char* netmask, uint8_t* prefix_length);
+
 #endif // INTERFACES_PLUGIN_DATA_INTERFACES_INTERFACE_IPV4_ADDRESS_H