Add new package libpacketmark, a LD_PRELOAD library to manipulate packet marks

This commit is contained in:
Matthias Schiffer 2014-07-29 04:31:29 +02:00
parent 167e7d5a1c
commit 59ba39ae96
3 changed files with 98 additions and 0 deletions

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include $(TOPDIR)/rules.mk
PKG_NAME:=libpacketmark
PKG_VERSION:=1
PKG_BUILD_DIR := $(BUILD_DIR)/$(PKG_NAME)
include $(INCLUDE_DIR)/package.mk
define Package/libpacketmark
SECTION:=libs
CATEGORY:=Libraries
TITLE:=Set default packet mark via LD_PRELOAD
DEPENDS:=
endef
define Build/Prepare
mkdir -p $(PKG_BUILD_DIR)
$(CP) ./src/* $(PKG_BUILD_DIR)/
endef
define Build/Configure
endef
define Build/Compile
CFLAGS="$(TARGET_CFLAGS)" CPPFLAGS="$(TARGET_CPPFLAGS)" $(MAKE) -C $(PKG_BUILD_DIR) $(TARGET_CONFIGURE_OPTS)
endef
define Package/libpacketmark/install
$(INSTALL_DIR) $(1)/usr/lib
$(CP) $(PKG_BUILD_DIR)/libpacketmark.so $(1)/usr/lib/
endef
$(eval $(call BuildPackage,libpacketmark))

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all: libpacketmark.so
libpacketmark.so: libpacketmark.c
$(CC) $(CPPFLAGS) $(CFLAGS) $(LDFLAGS) -Wall -nostartfiles -shared -fPIC -o $@ $^ -ldl $(LDLIBS)

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/*
Copyright (c) 2014, Matthias Schiffer <mschiffer@universe-factory.net>
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
1. Redistributions of source code must retain the above copyright notice,
this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#define _GNU_SOURCE
#include <dlfcn.h>
#include <errno.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
static int mark;
static int (*socket_real)(int domain, int type, int protocol);
void _init(void) {
const char *str = getenv("LIBPACKETMARK_MARK");
if (str)
mark = atoi(str);
socket_real = dlsym(RTLD_NEXT, "socket");
}
int socket(int domain, int type, int protocol) {
int fd = socket_real(domain, type, protocol);
if (fd >= 0) {
int errno_save = errno;
setsockopt(fd, SOL_SOCKET, SO_MARK, &mark, sizeof(mark));
errno = errno_save;
}
return fd;
}