icmp6-util: several cleanups for icmp6_receive()

- Rename the argument for storing the sender address,
- allow to call it with NULL for ret_xyz,
- reduce needless copy of timestamp when the message does not have
  timestamp.

(cherry picked from commit 5121163)

Author: yuwata

src/libsystemd-network/fuzz-ndisc-rs.c

@@ -24,12 +24,17 @@ int icmp6_bind_router_advertisement(int index) {
         return -ENOSYS;
 }
 
-int icmp6_receive(int fd, void *iov_base, size_t iov_len,
-                  struct in6_addr *dst, triple_timestamp *timestamp) {
+int icmp6_receive(
+                int fd,
+                void *iov_base,
+                size_t iov_len,
+                struct in6_addr *ret_sender,
+                triple_timestamp *ret_timestamp) {
+
         assert_se(read(fd, iov_base, iov_len) == (ssize_t) iov_len);
 
-        if (timestamp)
-                triple_timestamp_get(timestamp);
+        if (ret_timestamp)
+                triple_timestamp_get(ret_timestamp);
 
         return 0;
 }

src/libsystemd-network/icmp6-util.c

@@ -144,8 +144,12 @@ int icmp6_send_router_solicitation(int s, const struct ether_addr *ether_addr) {
         return 0;
 }
 
-int icmp6_receive(int fd, void *buffer, size_t size, struct in6_addr *ret_dst,
-                  triple_timestamp *ret_timestamp) {
+int icmp6_receive(
+                int fd,
+                void *buffer,
+                size_t size,
+                struct in6_addr *ret_sender,
+                triple_timestamp *ret_timestamp) {
 
         /* This needs to be initialized with zero. See #20741. */
         CMSG_BUFFER_TYPE(CMSG_SPACE(sizeof(int)) + /* ttl */
@@ -206,10 +210,14 @@ int icmp6_receive(int fd, void *buffer, size_t size, struct in6_addr *ret_dst,
                 }
         }
 
-        if (!triple_timestamp_is_set(&t))
-                triple_timestamp_get(&t);
+        if (ret_timestamp) {
+                if (triple_timestamp_is_set(&t))
+                        *ret_timestamp = t;
+                else
+                        triple_timestamp_get(ret_timestamp);
+        }
 
-        *ret_dst = addr;
-        *ret_timestamp = t;
+        if (ret_sender)
+                *ret_sender = addr;
         return 0;
 }

src/libsystemd-network/icmp6-util.h

@@ -20,5 +20,9 @@
 int icmp6_bind_router_solicitation(int ifindex);
 int icmp6_bind_router_advertisement(int ifindex);
 int icmp6_send_router_solicitation(int s, const struct ether_addr *ether_addr);
-int icmp6_receive(int fd, void *buffer, size_t size, struct in6_addr *ret_dst,
-                  triple_timestamp *ret_timestamp);
+int icmp6_receive(
+                int fd,
+                void *buffer,
+                size_t size,
+                struct in6_addr *ret_sender,
+                triple_timestamp *ret_timestamp);

src/libsystemd-network/test-ndisc-ra.c

@@ -223,12 +223,17 @@ int icmp6_send_router_solicitation(int s, const struct ether_addr *ether_addr) {
         return 0;
 }
 
-int icmp6_receive(int fd, void *iov_base, size_t iov_len,
-                  struct in6_addr *dst, triple_timestamp *timestamp) {
+int icmp6_receive(
+                int fd,
+                void *iov_base,
+                size_t iov_len,
+                struct in6_addr *ret_sender,
+                triple_timestamp *ret_timestamp) {
+
         assert_se(read (fd, iov_base, iov_len) == (ssize_t)iov_len);
 
-        if (timestamp)
-                triple_timestamp_get(timestamp);
+        if (ret_timestamp)
+                triple_timestamp_get(ret_timestamp);
 
         return 0;
 }

src/libsystemd-network/test-ndisc-rs.c

@@ -176,12 +176,17 @@ int icmp6_bind_router_advertisement(int ifindex) {
         return -ENOSYS;
 }
 
-int icmp6_receive(int fd, void *iov_base, size_t iov_len,
-                  struct in6_addr *dst, triple_timestamp *timestamp) {
+int icmp6_receive(
+                int fd,
+                void *iov_base,
+                size_t iov_len,
+                struct in6_addr *ret_sender,
+                triple_timestamp *ret_timestamp) {
+
         assert_se(read (fd, iov_base, iov_len) == (ssize_t)iov_len);
 
-        if (timestamp)
-                triple_timestamp_get(timestamp);
+        if (ret_timestamp)
+                triple_timestamp_get(ret_timestamp);
 
         return 0;
 }