Merge pull request #17855 from poettering/more-socktops

socket-util: some helpers for various sockopts

src/basic/missing_socket.h

@@ -67,6 +67,14 @@ struct sockaddr_vm {
 #define IPV6_FREEBIND 78
 #endif
 
+#ifndef IP_RECVFRAGSIZE
+#define IP_RECVFRAGSIZE 25
+#endif
+
+#ifndef IPV6_RECVFRAGSIZE
+#define IPV6_RECVFRAGSIZE 77
+#endif
+
 /* linux/sockios.h */
 #ifndef SIOCGSKNS
 #define SIOCGSKNS 0x894C

src/basic/socket-util.c

@@ -1314,3 +1314,35 @@ int socket_set_option(int fd, int af, int opt_ipv4, int opt_ipv6, int val) {
                 return -EAFNOSUPPORT;
         }
 }
+
+int socket_get_mtu(int fd, int af, size_t *ret) {
+        int mtu, r;
+
+        if (af == AF_UNSPEC) {
+                r = socket_get_family(fd, &af);
+                if (r < 0)
+                        return r;
+        }
+
+        switch (af) {
+
+        case AF_INET:
+                r = getsockopt_int(fd, IPPROTO_IP, IP_MTU, &mtu);
+                break;
+
+        case AF_INET6:
+                r = getsockopt_int(fd, IPPROTO_IPV6, IPV6_MTU, &mtu);
+                break;
+
+        default:
+                return -EAFNOSUPPORT;
+        }
+
+        if (r < 0)
+                return r;
+        if (mtu <= 0)
+                return -EINVAL;
+
+        *ret = (size_t) mtu;
+        return 0;
+}

src/basic/socket-util.h

@@ -258,6 +258,19 @@ static inline int setsockopt_int(int fd, int level, int optname, int value) {
         return 0;
 }
 
+static inline int getsockopt_int(int fd, int level, int optname, int *ret) {
+        int v;
+        socklen_t sl = sizeof(v);
+
+        if (getsockopt(fd, level, optname, &v, &sl) < 0)
+                return -errno;
+        if (sl != sizeof(v))
+                return -EIO;
+
+        *ret = v;
+        return 0;
+}
+
 int socket_bind_to_ifname(int fd, const char *ifname);
 int socket_bind_to_ifindex(int fd, int ifindex);
 
@@ -266,6 +279,7 @@ ssize_t recvmsg_safe(int sockfd, struct msghdr *msg, int flags);
 int socket_get_family(int fd, int *ret);
 int socket_set_recvpktinfo(int fd, int af, bool b);
 int socket_set_unicast_if(int fd, int af, int ifi);
+
 int socket_set_option(int fd, int af, int opt_ipv4, int opt_ipv6, int val);
 static inline int socket_set_recverr(int fd, int af, bool b) {
         return socket_set_option(fd, af, IP_RECVERR, IPV6_RECVERR, b);
@@ -282,3 +296,8 @@ static inline int socket_set_freebind(int fd, int af, bool b) {
 static inline int socket_set_transparent(int fd, int af, bool b) {
         return socket_set_option(fd, af, IP_TRANSPARENT, IPV6_TRANSPARENT, b);
 }
+static inline int socket_set_recvfragsize(int fd, int af, bool b) {
+        return socket_set_option(fd, af, IP_RECVFRAGSIZE, IPV6_RECVFRAGSIZE, b);
+}
+
+int socket_get_mtu(int fd, int af, size_t *ret);