dhcpv6: dhcpv6_parse_ia refactor to switch case

Add RFC comments for certain operations.

Signed-off-by: Paul Donald <[email protected]>
Link: https://github.com/openwrt/odhcp6c/pull/103
Signed-off-by: Álvaro Fernández Rojas <[email protected]>

diff --git a/src/dhcpv6.c b/src/dhcpv6.c
index 28a2de29f21c928946da65ba6e8a5fd73311e40a..3e6c9ba2ff8541903bde2744ad0bbfad7e147bfd 100644 (file)
--- a/src/dhcpv6.c
+++ b/src/dhcpv6.c
@@ -1370,6 +1370,11 @@ static unsigned int dhcpv6_parse_ia(void *opt, void *end)
        t1 = ntohl(ia_hdr->t1);
        t2 = ntohl(ia_hdr->t2);
 
+       /* RFC 8415 §21.4
+       If a client receives an IA_NA with T1 greater than T2 and both T1 and
+       T2 are greater than 0, the client discards the IA_NA option and
+       processes the remainder of the message as though the server had not
+       included the invalid IA_NA option. */
        if (t1 > t2 && t1 > 0 && t2 > 0)
                return 0;
 
@@ -1382,7 +1387,8 @@ static unsigned int dhcpv6_parse_ia(void *opt, void *end)
 
                entry.iaid = ia_hdr->iaid;
 
-               if (otype == DHCPV6_OPT_IA_PREFIX) {
+               switch (otype) {
+               case DHCPV6_OPT_IA_PREFIX: {
                        struct dhcpv6_ia_prefix *prefix = (void*)&odata[-4];
                        if (olen + 4U < sizeof(*prefix))
                                continue;
@@ -1393,6 +1399,10 @@ static unsigned int dhcpv6_parse_ia(void *opt, void *end)
                        if (entry.preferred > entry.valid)
                                continue;
 
+                       /*      RFC 8415 §21.21
+                       Recommended values for T1 and T2 are 0.5 and 0.8 times the
+                       shortest preferred lifetime of the prefixes in the IA_PD that the
+                       server is willing to extend. */
                        entry.t1 = (t1 ? t1 : (entry.preferred != UINT32_MAX ? 0.5 * entry.preferred : UINT32_MAX));
                        entry.t2 = (t2 ? t2 : (entry.preferred != UINT32_MAX ? 0.8 * entry.preferred : UINT32_MAX));
                        if (entry.t1 > entry.t2)
@@ -1407,6 +1417,7 @@ static unsigned int dhcpv6_parse_ia(void *opt, void *end)
                        bool ok = true;
                        dhcpv6_for_each_option(odata + sizeof(*prefix) - 4U,
                                        odata + olen, stype, slen, sdata) {
+                               /*      RFC 6603 §4.2 Prefix Exclude option */
                                if (stype != DHCPV6_OPT_PD_EXCLUDE || slen < 2)
                                        continue;
 
@@ -1444,13 +1455,15 @@ static unsigned int dhcpv6_parse_ia(void *opt, void *end)
                                        updated_IAs++;
 
                                syslog(LOG_INFO, "%s/%d preferred %d valid %d",
-                                      inet_ntop(AF_INET6, &entry.target, buf, sizeof(buf)),
-                                      entry.length, entry.preferred , entry.valid);
+                                               inet_ntop(AF_INET6, &entry.target, buf, sizeof(buf)),
+                                               entry.length, entry.preferred , entry.valid);
                        }
 
                        entry.priority = 0;
                        memset(&entry.router, 0, sizeof(entry.router));
-               } else if (otype == DHCPV6_OPT_IA_ADDR) {
+                       break;
+               }
+               case DHCPV6_OPT_IA_ADDR: {
                        struct dhcpv6_ia_addr *addr = (void*)&odata[-4];
                        if (olen + 4U < sizeof(*addr))
                                continue;
@@ -1473,8 +1486,12 @@ static unsigned int dhcpv6_parse_ia(void *opt, void *end)
                                updated_IAs++;
 
                        syslog(LOG_INFO, "%s preferred %d valid %d",
-                              inet_ntop(AF_INET6, &entry.target, buf, sizeof(buf)),
-                              entry.preferred , entry.valid);
+                                       inet_ntop(AF_INET6, &entry.target, buf, sizeof(buf)),
+                                       entry.preferred , entry.valid);
+                       break;
+               }
+               default:
+                       break;
                }
        }