Try to ignore the usual value restrictions of sockopt SO_RCVBUF when running

as root (with CAP_NET_ADMIN) by using SO_RCVBUFFORCE if possible.

diff --git a/candump.c b/candump.c
index 2cf7ed42f308be235dc9c8f1ccf0ea544f11d745..cc81b3f336d820fd2313a7993aaa7382928a4ebd 100644 (file)
--- a/candump.c
+++ b/candump.c
@@ -355,7 +355,7 @@ int main(int argc, char **argv)
 
        if (silent == SILENT_INI) {
                if (log) {
-                       fprintf(stderr, "\nDisabled standard output while logging.");
+                       fprintf(stderr, "Disabled standard output while logging.\n");
                        silent = SILENT_ON; /* disable output on stdout */
                } else
                        silent = SILENT_OFF; /* default output */
@@ -482,23 +482,30 @@ int main(int argc, char **argv)
                        int curr_rcvbuf_size;
                        socklen_t curr_rcvbuf_size_len = sizeof(curr_rcvbuf_size);
 
-                       if (setsockopt(s[i], SOL_SOCKET, SO_RCVBUF,
+                       /* try SO_RCVBUFFORCE first, if we run with CAP_NET_ADMIN */
+                       if (setsockopt(s[i], SOL_SOCKET, SO_RCVBUFFORCE,
                                       &rcvbuf_size, sizeof(rcvbuf_size)) < 0) {
-                               perror("setsockopt SO_RCVBUF");
-                               return 1;
-                       }
+#ifdef DEBUG
+                               printf("SO_RCVBUFFORCE failed so try SO_RCVBUF ...\n");
+#endif
+                               if (setsockopt(s[i], SOL_SOCKET, SO_RCVBUF,
+                                              &rcvbuf_size, sizeof(rcvbuf_size)) < 0) {
+                                       perror("setsockopt SO_RCVBUF");
+                                       return 1;
+                               }
 
-                       if (getsockopt(s[i], SOL_SOCKET, SO_RCVBUF,
-                                      &curr_rcvbuf_size, &curr_rcvbuf_size_len) < 0) {
-                               perror("getsockopt SO_RCVBUF");
-                               return 1;
-                       }
+                               if (getsockopt(s[i], SOL_SOCKET, SO_RCVBUF,
+                                              &curr_rcvbuf_size, &curr_rcvbuf_size_len) < 0) {
+                                       perror("getsockopt SO_RCVBUF");
+                                       return 1;
+                               }
 
-                       /* Only print a warning the first time we detect the adjustment */
-                       /* n.b.: The wanted size is doubled in Linux in net/sore/sock.c */
-                       if (!i && curr_rcvbuf_size < rcvbuf_size*2)
-                               fprintf(stderr, "The socket receive buffer size was "
-                                       "adjusted due to /proc/sys/net/core/rmem_max.\n");
+                               /* Only print a warning the first time we detect the adjustment */
+                               /* n.b.: The wanted size is doubled in Linux in net/sore/sock.c */
+                               if (!i && curr_rcvbuf_size < rcvbuf_size*2)
+                                       fprintf(stderr, "The socket receive buffer size was "
+                                               "adjusted due to /proc/sys/net/core/rmem_max.\n");
+                       }
                }
 
                if (timestamp || log || logfrmt) {