POTD skeleton #82.

Signed-off-by: Toni Uhlig <matzeton@googlemail.com>

2 files changed, 57 insertions, 4 deletions

diff --git a/configure.ac b/configure.ac
index 5edde66..34bd487 100644
--- a/configure.ac
+++ b/configure.ac
@@ -62,16 +62,47 @@ AC_SUBST([valgrind_CFLAGS])
 AC_SUBST([valgrind_LIBS])
 
 dnl Check for std header files
-AC_CHECK_HEADERS([stdio.h ctype.h assert.h sched.h signal.h errno.h pwd.h])
+AC_CHECK_HEADERS([stdio.h ctype.h assert.h sched.h signal.h time.h errno.h pwd.h], [],
+      [ AC_MSG_ERROR([required std header not available]) ])
 
 dnl Check for system specific header files
-AC_CHECK_HEADERS([pty.h linux/capability.h sys/wait.h])
+AC_CHECK_HEADERS([pty.h linux/capability.h sys/wait.h], [],
+      [ AC_MSG_ERROR([required system specific header not available]) ])
 AC_CHECK_HEADERS([libutil.h pthread.h syslog.h sys/prctl.h linux/limits.h \
                   sys/uio.h poll.h sys/epoll.h sys/sysmacros.h sys/mount.h util.h])
 
 dnl Check for GAI header
 AC_CHECK_HEADERS([netdb.h])
 
+AC_MSG_CHECKING([working time])
+AC_COMPILE_IFELSE([
+      AC_LANG_SOURCE([#include <time.h>
+        int fn(void) \
+        { time_t s0 = time(NULL); \
+          time_t s1 = time(NULL); \
+		  double r = difftime(s0, s1); }])
+      ],
+      AC_MSG_RESULT([yes]),
+      [ AC_MSG_RESULT([no])
+        AC_MSG_ERROR([time is not available on your platform]) ])
+
+AC_MSG_CHECKING([for working epoll])
+AC_COMPILE_IFELSE([
+      AC_LANG_SOURCE([#include <sys/epoll.h>
+                      #include <signal.h>
+        int fn(void) \
+        { int fd = epoll_create1(0); \
+          struct epoll_event ev = {0,{0}}; \
+          struct epoll_event polled[[16]]; \
+          sigset_t eset; sigemptyset(&eset); \
+          epoll_ctl(fd, EPOLL_CTL_ADD, 0, &ev); \
+          epoll_pwait(fd, polled, 16, -1, &eset); \
+          close(fd); }])
+      ],
+      AC_MSG_RESULT([yes]),
+      [ AC_MSG_RESULT([no])
+        AC_MSG_ERROR([epoll is not available on your platform]) ])
+
 AC_MSG_CHECKING([for working va_arg])
 AC_COMPILE_IFELSE([
       AC_LANG_SOURCE([#include <stdio.h>
@@ -139,7 +170,8 @@ AC_CHECK_FUNCS([open read write close malloc free memset memcpy fork unshare \
                 wait waitpid isprint remove unlink mkdir access stat chroot chdir mount umount mknod \
                 strncat strncpy snprintf vsnprintf printf fprintf getpid \
                 prctl signal signalfd fcntl getenv kill exit \
-                setsockopt socket connect accept bind listen], [],
+                setsockopt socket connect accept bind listen \
+                time difftime], [],
       [ AC_MSG_ERROR([required function not available]) ])
 dnl GAI functions
 AC_CHECK_FUNCS([getaddrinfo getnameinfo freeaddrinfo], [],
diff --git a/src/redirector.c b/src/redirector.c
index be3802f..b4d7a78 100644
--- a/src/redirector.c
+++ b/src/redirector.c
@@ -4,6 +4,7 @@
 #include <string.h>
 #include <signal.h>
 #include <pthread.h>
+#include <time.h>
 #include <assert.h>
 
 #include "redirector.h"
@@ -21,6 +22,8 @@ typedef struct client_thread {
 typedef struct server_event {
     redirector_ctx **rdr_ctx;
     const size_t siz;
+    size_t last_accept_count;
+    time_t last_accept_stamp;
 } server_event;
 
 typedef struct client_event {
@@ -222,11 +225,12 @@ fwd_state_string(const forward_state c_state, const client_thread *args,
 static int redirector_mainloop(event_ctx **ev_ctx, redirector_ctx *rdr_ctx[], size_t siz)
 {
     int rc;
-    server_event ev_srv = { rdr_ctx, siz };
+    server_event ev_srv = { rdr_ctx, siz, 0, 0 };
 
     set_procname("[potd] redirector");
     assert( set_child_sighandler() == 0 );
 
+    ev_srv.last_accept_stamp = time(NULL);
     rc = event_loop(*ev_ctx, redirector_accept_client, &ev_srv);
     event_free(ev_ctx);
 
@@ -236,7 +240,9 @@ static int redirector_mainloop(event_ctx **ev_ctx, redirector_ctx *rdr_ctx[], si
 static int redirector_accept_client(event_ctx *ev_ctx, int fd, void *user_data)
 {
     size_t i;
+    double d;
     int s;
+    time_t t;
     server_event *ev_srv = (server_event *) user_data;
     client_thread *args;
     redirector_ctx *rdr_ctx;
@@ -258,6 +264,21 @@ static int redirector_accept_client(event_ctx *ev_ctx, int fd, void *user_data)
                 goto error;
             }
 
+            ev_srv->last_accept_count++;
+            t = time(NULL);
+            d = difftime(t, ev_srv->last_accept_stamp);
+            if (d == 0.0f)
+                d = 1.0f;
+            if (d > 5.0f) {
+                ev_srv->last_accept_stamp = t;
+                ev_srv->last_accept_count = 0;
+            }
+            if (ev_srv->last_accept_count / (size_t)d > 3) {
+                W2("DoS protection: Got %zu accepts/s",
+                    ev_srv->last_accept_count / (size_t)d);
+                goto error;
+            }
+
             args->rdr_ctx = rdr_ctx;
             s = socket_addrtostr_in(&args->client_sock,
                                     args->host_buf, args->service_buf);