init: Support parsing of IPv4 CIDR (`UK_NETDEV_IPV4_CIDR`)

This commit introduces support for parsing a statically assigned IP address
from the the netdev's extended information (einfo) field:
`UK_NETDEV_IPV4_CIDR`. The CIDR notation is provided in preference by
`lib/uknetdev` and must be read before looking into `UK_NETDEV_IPV4_ADDR`
and `UK_NETDEV_IPV4_MASK` fields.

Signed-off-by: Simon Kuenzer <simon@unikraft.io>
Reviewed-by: Stefan Jumarea <stefanjumarea02@gmail.com>
Approved-by: Razvan Deaconescu <razvand@unikraft.io>
GitHub-Closes: #42

diff --git a/init.c b/init.c
index 3402380f25687cdd4337ae52f80ce058dc078386..49eb04ce5ebda36bd7aa009a517abadf367a44ae 100644 (file)
--- a/init.c
+++ b/init.c
@@ -32,6 +32,7 @@
  */
 
 #include <uk/config.h>
+#include <string.h>
 #include "lwip/opt.h"
 #include "lwip/tcpip.h"
 #include "lwip/init.h"
@@ -202,6 +203,55 @@ static int liblwip_init(struct uk_init_ctx *ictx __unused)
                mask4_arg = NULL;
                gw4_arg   = NULL;
 
+               /* CIDR (IP and mask) */
+               strcfg = uk_netdev_einfo_get(dev, UK_NETDEV_IPV4_CIDR);
+               if (strcfg) {
+                       long maskbits;
+                       char str_ipaddr[16]; /* Can hold "255.255.255.255\0" */
+                       size_t strlen_ipaddr;
+                       const char *str_maskbits;
+
+                       str_maskbits = strchr(strcfg, '/');
+                       if (!str_maskbits) {
+                               uk_pr_err("Failed to find maskbits separator of CIDR IP address: %s\n",
+                                         strcfg);
+                               goto ipv4_legacy;
+                       }
+                       strlen_ipaddr = (size_t) str_maskbits - (size_t) strcfg;
+                       if (strlen_ipaddr > ARRAY_SIZE(str_ipaddr)) {
+                               uk_pr_err("IP address length out of range: %s\n",
+                                         str_ipaddr);
+                               goto ipv4_legacy;
+                       }
+                       strncpy(str_ipaddr, strcfg, strlen_ipaddr);
+                       str_ipaddr[strlen_ipaddr] = '\0';
+                       str_maskbits++; /* skip '/' */
+
+                       if (ip4addr_aton(str_ipaddr, &ip4) != 1) {
+                               uk_pr_err("Error converting IP address: %s\n",
+                                         str_ipaddr);
+                               goto ipv4_legacy;
+                       }
+                       maskbits = strtol(str_maskbits, NULL, 10);
+                       if (maskbits < 0 || maskbits > 32) {
+                               uk_pr_err("Mask bits out of range: %s\n",
+                                         str_ipaddr);
+                               goto ipv4_legacy;
+                       }
+                       ip4_addr_set_u32(&mask4,
+                                        lwip_htonl(~(__u32)((1LL <<
+                                                       (32 - maskbits)) - 1)));
+
+                       uk_pr_debug("Detected IP from IPv4 CIDR: %s\n",
+                                   str_ipaddr);
+                       uk_pr_debug("Detected mask bits from IPv4 CIDR: %ld\n",
+                                   maskbits);
+                       ip4_arg = &ip4;
+                       mask4_arg = &mask4;
+                       goto ipv4_gw;
+               }
+
+ipv4_legacy:
                /* IP */
                strcfg = uk_netdev_einfo_get(dev, UK_NETDEV_IPV4_ADDR);
                if (strcfg) {
@@ -227,6 +277,7 @@ static int liblwip_init(struct uk_init_ctx *ictx __unused)
                        ip4_addr_set_u32(&mask4, lwip_htonl(IP_CLASSC_NET));
                mask4_arg = &mask4;
 
+ipv4_gw:
                /* gateway */
                strcfg = uk_netdev_einfo_get(dev, UK_NETDEV_IPV4_GW);
                if (strcfg) {