socket-util: New function get_socket_rcvbuf().

This will be used in an upcoming commit.

diff --git a/lib/socket-util.c b/lib/socket-util.c
index 65b57ca..26e2908 100644 (file)
--- a/lib/socket-util.c
+++ b/lib/socket-util.c
@@ -59,6 +59,9 @@ VLOG_DEFINE_THIS_MODULE(socket_util);
 #define O_DIRECTORY 0
 #endif
 
+static int getsockopt_int(int fd, int level, int option, const char *optname,
+                          int *valuep);
+
 /* Sets 'fd' to non-blocking mode.  Returns 0 if successful, otherwise a
  * positive errno value. */
 int
@@ -182,11 +185,9 @@ int
 get_socket_error(int fd)
 {
     int error;
-    socklen_t len = sizeof(error);
-    if (getsockopt(fd, SOL_SOCKET, SO_ERROR, &error, &len) < 0) {
-        static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 10);
+
+    if (getsockopt_int(fd, SOL_SOCKET, SO_ERROR, "SO_ERROR", &error)) {
         error = errno;
-        VLOG_ERR_RL(&rl, "getsockopt(SO_ERROR): %s", strerror(error));
     }
     return error;
 }
@@ -221,15 +222,13 @@ check_connection_completion(int fd)
 int
 drain_rcvbuf(int fd)
 {
-    socklen_t rcvbuf_len;
-    size_t rcvbuf = 0;
+    int rcvbuf;
 
-    rcvbuf_len = sizeof rcvbuf;
-    if (getsockopt(fd, SOL_SOCKET, SO_RCVBUF, &rcvbuf, &rcvbuf_len) < 0) {
-        static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 10);
-        VLOG_ERR_RL(&rl, "getsockopt(SO_RCVBUF) failed: %s", strerror(errno));
-        return errno;
+    rcvbuf = get_socket_rcvbuf(fd);
+    if (rcvbuf < 0) {
+        return -rcvbuf;
     }
+
     while (rcvbuf > 0) {
         /* In Linux, specifying MSG_TRUNC in the flags argument causes the
          * datagram length to be returned, even if that is longer than the
@@ -250,6 +249,18 @@ drain_rcvbuf(int fd)
     return 0;
 }
 
+/* Returns the size of socket 'sock''s receive buffer (SO_RCVBUF), or a
+ * negative errno value if an error occurs. */
+int
+get_socket_rcvbuf(int sock)
+{
+    int rcvbuf;
+    int error;
+
+    error = getsockopt_int(sock, SOL_SOCKET, SO_RCVBUF, "SO_RCVBUF", &rcvbuf);
+    return error ? -error : rcvbuf;
+}
+
 /* Reads and discards up to 'n' datagrams from 'fd', stopping as soon as no
  * more data can be immediately read.  ('fd' should therefore be in
  * non-blocking mode.)*/
@@ -846,13 +857,27 @@ xpipe(int fds[2])
 }
 
 static int
-getsockopt_int(int fd, int level, int optname, int *valuep)
+getsockopt_int(int fd, int level, int option, const char *optname, int *valuep)
 {
-    socklen_t len = sizeof *valuep;
+    static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 10);
+    socklen_t len;
+    int value;
+    int error;
 
-    return (getsockopt(fd, level, optname, valuep, &len) ? errno
-            : len == sizeof *valuep ? 0
-            : EINVAL);
+    len = sizeof value;
+    if (getsockopt(fd, level, option, &value, &len)) {
+        error = errno;
+        VLOG_ERR_RL(&rl, "getsockopt(%s): %s", optname, strerror(error));
+    } else if (len != sizeof value) {
+        error = EINVAL;
+        VLOG_ERR_RL(&rl, "getsockopt(%s): value is %u bytes (expected %zu)",
+                    optname, (unsigned int) len, sizeof value);
+    } else {
+        error = 0;
+    }
+
+    *valuep = error ? 0 : value;
+    return error;
 }
 
 static void
@@ -890,7 +915,8 @@ describe_sockaddr(struct ds *string, int fd,
 #define SO_PROTOCOL 38
 #endif
 
-            if (!getsockopt_int(fd, SOL_SOCKET, SO_PROTOCOL, &protocol)) {
+            if (!getsockopt_int(fd, SOL_SOCKET, SO_PROTOCOL, "SO_PROTOCOL",
+                                &protocol)) {
                 switch (protocol) {
                 case NETLINK_ROUTE:
                     ds_put_cstr(string, "NETLINK_ROUTE");

diff --git a/lib/socket-util.h b/lib/socket-util.h
index 1059139..422cea9 100644 (file)
--- a/lib/socket-util.h
+++ b/lib/socket-util.h
@@ -33,6 +33,7 @@ int lookup_ipv6(const char *host_name, struct in6_addr *address);
 int lookup_hostname(const char *host_name, struct in_addr *);
 
 int get_socket_error(int sock);
+int get_socket_rcvbuf(int sock);
 int check_connection_completion(int fd);
 int drain_rcvbuf(int fd);
 void drain_fd(int fd, size_t n_packets);