From: Roy Marples <roy@marples.name>
Date: Wed, 2 Oct 2019 16:01:02 +0000 (+0100)
Subject: inet: Rework prior incase DHCP uses an IPv4LL address
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=cd016919a0cd4265f99750b5f8100b1d6db48cca;p=thirdparty%2Fdhcpcd.git

inet: Rework prior incase DHCP uses an IPv4LL address

Highly unlikely, but still technically possible.
---

diff --git a/src/dhcp.c b/src/dhcp.c
index 6145ce9c..fd4ee9f4 100644
--- a/src/dhcp.c
+++ b/src/dhcp.c
@@ -2013,19 +2013,20 @@ dhcp_finish_dad(struct interface *ifp, struct in_addr *ia)
 }
 
 
-static void
+static bool
 dhcp_addr_duplicated(struct interface *ifp, struct in_addr *ia)
 {
 	struct dhcp_state *state = D_STATE(ifp);
 	unsigned long long opts = ifp->options->options;
 	struct dhcpcd_ctx *ctx = ifp->ctx;
+	bool deleted = false;
 #ifdef IN_IFF_DUPLICATED
 	struct ipv4_addr *iap;
 #endif
 
 	if ((state->offer == NULL || state->offer->yiaddr != ia->s_addr) &&
 	    !IN_ARE_ADDR_EQUAL(ia, &state->lease.addr))
-		return;
+		return deleted;
 
 	/* RFC 2131 3.1.5, Client-server interaction */
 	logerrx("%s: DAD detected %s", ifp->name, inet_ntoa(*ia));
@@ -2033,8 +2034,10 @@ dhcp_addr_duplicated(struct interface *ifp, struct in_addr *ia)
 	if (!(opts & DHCPCD_STATIC) && !state->lease.frominfo)
 		dhcp_decline(ifp);
 #ifdef IN_IFF_DUPLICATED
-	if ((iap = ipv4_iffindaddr(ifp, ia, NULL)) != NULL)
+	if ((iap = ipv4_iffindaddr(ifp, ia, NULL)) != NULL) {
 		ipv4_deladdr(iap, 0);
+		deleted = true;
+	}
 #endif
 	eloop_timeout_delete(ctx->eloop, NULL, ifp);
 	if (opts & (DHCPCD_STATIC | DHCPCD_INFORM)) {
@@ -2042,10 +2045,11 @@ dhcp_addr_duplicated(struct interface *ifp, struct in_addr *ia)
 		script_runreason(ifp, state->reason);
 		if (!(ctx->options & DHCPCD_MASTER))
 			eloop_exit(ifp->ctx->eloop, EXIT_FAILURE);
-		return;
+		return deleted;
 	}
 	eloop_timeout_add_sec(ifp->ctx->eloop,
 	    DHCP_RAND_MAX, dhcp_discover, ifp);
+	return deleted;
 }
 #endif
 
@@ -3963,7 +3967,7 @@ dhcp_abort(struct interface *ifp)
 	}
 }
 
-void
+struct ipv4_addr *
 dhcp_handleifa(int cmd, struct ipv4_addr *ia, pid_t pid)
 {
 	struct interface *ifp;
@@ -3974,7 +3978,7 @@ dhcp_handleifa(int cmd, struct ipv4_addr *ia, pid_t pid)
 	ifp = ia->iface;
 	state = D_STATE(ifp);
 	if (state == NULL || state->state == DHS_NONE)
-		return;
+		return ia;
 
 	if (cmd == RTM_DELADDR) {
 		if (state->addr == ia) {
@@ -3985,37 +3989,37 @@ dhcp_handleifa(int cmd, struct ipv4_addr *ia, pid_t pid)
 			 * to drop the lease. */
 			dhcp_drop(ifp, "EXPIRE");
 			dhcp_start1(ifp);
+			return NULL;
 		}
-		return;
 	}
 
 	if (cmd != RTM_NEWADDR)
-		return;
+		return ia;
 
 #ifdef IN_IFF_NOTUSEABLE
 	if (!(ia->addr_flags & IN_IFF_NOTUSEABLE))
 		dhcp_finish_dad(ifp, &ia->addr);
 	else if (ia->addr_flags & IN_IFF_DUPLICATED)
-		dhcp_addr_duplicated(ifp, &ia->addr);
+		return dhcp_addr_duplicated(ifp, &ia->addr) ? NULL : ia;
 #endif
 
 	ifo = ifp->options;
 	if (ifo->options & DHCPCD_INFORM) {
 		if (state->state != DHS_INFORM)
 			dhcp_inform(ifp);
-		return;
+		return ia;
 	}
 
 	if (!(ifo->options & DHCPCD_STATIC))
-		return;
+		return ia;
 	if (ifo->req_addr.s_addr != INADDR_ANY)
-		return;
+		return ia;
 
 	free(state->old);
 	state->old = state->new;
 	state->new_len = dhcp_message_new(&state->new, &ia->addr, &ia->mask);
 	if (state->new == NULL)
-		return;
+		return ia;
 	if (ifp->flags & IFF_POINTOPOINT) {
 		for (i = 1; i < 255; i++)
 			if (i != DHO_ROUTER && has_option_mask(ifo->dstmask,i))
@@ -4031,4 +4035,6 @@ dhcp_handleifa(int cmd, struct ipv4_addr *ia, pid_t pid)
 		state->addr = ia;
 		dhcp_inform(ifp);
 	}
+
+	return ia;
 }
diff --git a/src/dhcp.h b/src/dhcp.h
index 4b6311a3..98a8b1e4 100644
--- a/src/dhcp.h
+++ b/src/dhcp.h
@@ -260,7 +260,7 @@ int dhcp_get_routes(rb_tree_t *, struct interface *);
 ssize_t dhcp_env(FILE *, const char *, const struct interface *,
     const struct bootp *, size_t);
 
-void dhcp_handleifa(int, struct ipv4_addr *, pid_t pid);
+struct ipv4_addr *dhcp_handleifa(int, struct ipv4_addr *, pid_t pid);
 void dhcp_drop(struct interface *, const char *);
 void dhcp_start(struct interface *);
 void dhcp_abort(struct interface *);
diff --git a/src/ipv4.c b/src/ipv4.c
index ff30fda0..8c89dc73 100644
--- a/src/ipv4.c
+++ b/src/ipv4.c
@@ -936,19 +936,14 @@ ipv4_handleifa(struct dhcpcd_ctx *ctx,
 	}
 
 	if (addr->s_addr != INADDR_ANY && addr->s_addr != INADDR_BROADCAST) {
-		/* If the handler deletes the address, the other might crash.
-		 * So only call one handler based on the address type. */
-		if (IN_LINKLOCAL(ntohl(addr->s_addr)))
+		ia = dhcp_handleifa(cmd, ia, pid);
 #ifdef IPV4LL
+		if (ia != NULL)
 			ipv4ll_handleifa(cmd, ia, pid);
-#else
-			;
 #endif
-		else
-			dhcp_handleifa(cmd, ia, pid);
 	}
 
-	if (cmd == RTM_DELADDR)
+	if (cmd == RTM_DELADDR && ia != NULL)
 		free(ia);
 }
 
diff --git a/src/ipv4ll.c b/src/ipv4ll.c
index 2524a02f..09d1166f 100644
--- a/src/ipv4ll.c
+++ b/src/ipv4ll.c
@@ -546,7 +546,7 @@ ipv4ll_recvrt(__unused int cmd, const struct rt *rt)
 }
 #endif
 
-void
+struct ipv4_addr *
 ipv4ll_handleifa(int cmd, struct ipv4_addr *ia, pid_t pid)
 {
 	struct interface *ifp;
@@ -555,7 +555,7 @@ ipv4ll_handleifa(int cmd, struct ipv4_addr *ia, pid_t pid)
 	ifp = ia->iface;
 	state = IPV4LL_STATE(ifp);
 	if (state == NULL)
-		return;
+		return ia;
 
 	if (cmd == RTM_DELADDR &&
 	    state->addr != NULL &&
@@ -564,20 +564,23 @@ ipv4ll_handleifa(int cmd, struct ipv4_addr *ia, pid_t pid)
 		loginfox("%s: pid %d deleted IP address %s",
 		    ifp->name, pid, ia->saddr);
 		ipv4ll_defend_failed(ifp);
-		return;
+		return ia;
 	}
 
 #ifdef IN_IFF_DUPLICATED
 	if (cmd != RTM_NEWADDR)
-		return;
+		return ia;
 	if (!IN_ARE_ADDR_EQUAL(&state->pickedaddr, &ia->addr))
-		return;
+		return ia;
 	if (!(ia->addr_flags & IN_IFF_NOTUSEABLE))
 		ipv4ll_not_found(ifp);
 	else if (ia->addr_flags & IN_IFF_DUPLICATED) {
 		logerrx("%s: DAD detected %s", ifp->name, ia->saddr);
 		ipv4_deladdr(ia, 1);
 		ipv4ll_found(ifp);
+		return NULL;
 	}
 #endif
+
+	return ia;
 }
diff --git a/src/ipv4ll.h b/src/ipv4ll.h
index dd68d30a..d955d1e0 100644
--- a/src/ipv4ll.h
+++ b/src/ipv4ll.h
@@ -64,7 +64,7 @@ ssize_t ipv4ll_env(FILE *, const char *, const struct interface *);
 void ipv4ll_start(void *);
 void ipv4ll_claimed(void *);
 void ipv4ll_handle_failure(void *);
-void ipv4ll_handleifa(int, struct ipv4_addr *, pid_t pid);
+struct ipv4_addr *ipv4ll_handleifa(int, struct ipv4_addr *, pid_t pid);
 #ifdef HAVE_ROUTE_METRIC
 int ipv4ll_recvrt(int, const struct rt *);
 #endif