interfaces: fallback to link local addresses for management

When no global address is found for a family, we fallback to a link
local address instead. For IPv4, this is 169.254.0.0/16 and for IPv6,
this is fe80::/64.

Closes #96.

diff --git a/src/daemon/interfaces.c b/src/daemon/interfaces.c
index 4f48fde1c83c282d23ea4f2645057b9daaf7f3ec..10a498a964ef8af3d3456363b378517baea12238 100644 (file)
--- a/src/daemon/interfaces.c
+++ b/src/daemon/interfaces.c
@@ -352,6 +352,80 @@ interfaces_helper_chassis(struct lldpd *cfg,
 #define IN6_IS_ADDR_GLOBAL(a) \
        (!IN6_IS_ADDR_LOOPBACK(a) && !IN6_IS_ADDR_LINKLOCAL(a))
 
+/* Add management addresses for the given family. We only take one of each
+   address family, unless a pattern is provided and is not all negative. For
+   example !*:*,!10.* will only blacklist addresses. We will pick the first IPv4
+   address not matching 10.*.
+*/
+static int
+interfaces_helper_mgmt_for_af(struct lldpd *cfg,
+    int af,
+    struct interfaces_address_list *addrs,
+    int global, int allnegative)
+{
+       struct interfaces_address *addr;
+       struct lldpd_mgmt *mgmt;
+       char addrstrbuf[INET6_ADDRSTRLEN];
+       int found = 0;
+       void *sin_addr_ptr;
+       size_t sin_addr_size;
+
+       TAILQ_FOREACH(addr, addrs, next) {
+               if (addr->address.ss_family != lldpd_af(af))
+                       continue;
+
+               switch (af) {
+               case LLDPD_AF_IPV4:
+                       sin_addr_ptr = &((struct sockaddr_in *)&addr->address)->sin_addr;
+                       sin_addr_size = sizeof(struct in_addr);
+                       if (global) {
+                               if (!IN_IS_ADDR_GLOBAL((struct in_addr *)sin_addr_ptr))
+                                       continue;
+                       } else {
+                               if (!IN_IS_ADDR_LINKLOCAL((struct in_addr *)sin_addr_ptr))
+                                       continue;
+                       }
+                       break;
+               case LLDPD_AF_IPV6:
+                       sin_addr_ptr = &((struct sockaddr_in6 *)&addr->address)->sin6_addr;
+                       sin_addr_size = sizeof(struct in6_addr);
+                       if (global) {
+                               if (!IN6_IS_ADDR_GLOBAL((struct in6_addr *)sin_addr_ptr))
+                                       continue;
+                       } else {
+                               if (!IN6_IS_ADDR_LINKLOCAL((struct in6_addr *)sin_addr_ptr))
+                                       continue;
+                       }
+                       break;
+               default:
+                       assert(0);
+                       continue;
+               }
+               if (inet_ntop(lldpd_af(af), sin_addr_ptr,
+                       addrstrbuf, sizeof(addrstrbuf)) == NULL) {
+                       log_warn("interfaces", "unable to convert IP address to a string");
+                       continue;
+               }
+               if (cfg->g_config.c_mgmt_pattern == NULL ||
+                   pattern_match(addrstrbuf, cfg->g_config.c_mgmt_pattern, allnegative)) {
+                       mgmt = lldpd_alloc_mgmt(af, sin_addr_ptr, sin_addr_size,
+                           addr->index);
+                       if (mgmt == NULL) {
+                               assert(errno == ENOMEM); /* anything else is a bug */
+                               log_warn("interfaces", "out of memory error");
+                               return found;
+                       }
+                       log_debug("interfaces", "add management address %s", addrstrbuf);
+                       TAILQ_INSERT_TAIL(&LOCAL_CHASSIS(cfg)->c_mgmt, mgmt, m_entries);
+                       found = 1;
+
+                       /* Don't take additional address if the pattern is all negative. */
+                       if (allnegative) break;
+               }
+       }
+       return found;
+}
+
 /* Find a management address in all available interfaces, even those that were
    already handled. This is a special interface handler because it does not
    really handle interface related information (management address is attached
@@ -360,13 +434,8 @@ void
 interfaces_helper_mgmt(struct lldpd *cfg,
     struct interfaces_address_list *addrs)
 {
-       struct interfaces_address *addr;
-       char addrstrbuf[INET6_ADDRSTRLEN];
-       struct lldpd_mgmt *mgmt;
-       void *sin_addr_ptr;
-       size_t sin_addr_size;
-       int af;
        int allnegative = 0;
+       int af;
 
        lldpd_chassis_mgmt_cleanup(LOCAL_CHASSIS(cfg));
 
@@ -383,53 +452,8 @@ interfaces_helper_mgmt(struct lldpd *cfg,
 
        /* Find management addresses */
        for (af = LLDPD_AF_UNSPEC + 1; af != LLDPD_AF_LAST; af++) {
-               /* We only take one of each address family, unless a
-                  pattern is provided and is not all negative. For
-                  example !*:*,!10.* will only blacklist
-                  addresses. We will pick the first IPv4 address not
-                  matching 10.*. */
-               TAILQ_FOREACH(addr, addrs, next) {
-                       if (addr->address.ss_family != lldpd_af(af))
-                               continue;
-
-                       switch (af) {
-                       case LLDPD_AF_IPV4:
-                               sin_addr_ptr = &((struct sockaddr_in *)&addr->address)->sin_addr;
-                               sin_addr_size = sizeof(struct in_addr);
-                               if (!IN_IS_ADDR_GLOBAL((struct in_addr *)sin_addr_ptr))
-                                       continue;
-                               break;
-                       case LLDPD_AF_IPV6:
-                               sin_addr_ptr = &((struct sockaddr_in6 *)&addr->address)->sin6_addr;
-                               sin_addr_size = sizeof(struct in6_addr);
-                               if (!IN6_IS_ADDR_GLOBAL((struct in6_addr *)sin_addr_ptr))
-                                       continue;
-                               break;
-                       default:
-                               assert(0);
-                               continue;
-                       }
-                       if (inet_ntop(lldpd_af(af), sin_addr_ptr,
-                               addrstrbuf, sizeof(addrstrbuf)) == NULL) {
-                               log_warn("interfaces", "unable to convert IP address to a string");
-                               continue;
-                       }
-                       if (cfg->g_config.c_mgmt_pattern == NULL ||
-                           pattern_match(addrstrbuf, cfg->g_config.c_mgmt_pattern, allnegative)) {
-                               mgmt = lldpd_alloc_mgmt(af, sin_addr_ptr, sin_addr_size,
-                                                       addr->index);
-                               if (mgmt == NULL) {
-                                       assert(errno == ENOMEM); /* anything else is a bug */
-                                       log_warn("interfaces", "out of memory error");
-                                       return;
-                               }
-                               log_debug("interfaces", "add management address %s", addrstrbuf);
-                               TAILQ_INSERT_TAIL(&LOCAL_CHASSIS(cfg)->c_mgmt, mgmt, m_entries);
-
-                               /* Don't take additional address if the pattern is all negative. */
-                               if (allnegative) break;
-                       }
-               }
+               (void)(interfaces_helper_mgmt_for_af(cfg, af, addrs, 1, allnegative) ||
+                   interfaces_helper_mgmt_for_af(cfg, af, addrs, 0, allnegative));
        }
 }