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//
// redirect_to_local_http
//
// Description:
//
//
// Author: <king@tao.kingstone>, (C) 2009
//
// Copyright: See COPYING file that comes with this distribution
//
#include <stdio.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/tcp.h>
#include <netinet/udp.h>
#include <time.h>
#include <libnet.h>
#include <glib-2.0/glib.h>
#include <gio/gio.h>
#include <gmodule.h>
#include <glib/gi18n.h>
//#include "global.h"
//#include "pcap_hander.h"
#include <pcap.h>
//#include "clientmgr.h"
static void init_thread_libnet();
static void redirector_host_resove_by_dns(GObject *source_object, GAsyncResult *res, gpointer user_data);
#define HTTP_PORT 0x5000
#define DNS_PORT 0x3500
#define GROUP_NAME "http_redirect"
static u_int8_t httphead[512];
static u_int8_t httphead_t[] =
"HTTP/1.0 302 Found\n"
"Location: %s\n"
"Connection:close\n\n"
"<html>\n\t<head>\n\t\t<meta http-equiv=\"Refresh\"content=\"0 ; "
"url=%s\">\n\t</head>\n</html>\n";
static in_addr_t redirector_ip;
static GList* whiteip;
static __thread libnet_t * libnet = NULL;
static u_int8_t blank[128];
static void http_redirector_init(const gchar * desturl)
{
char host[128];
sscanf(desturl,"http://%128[^/^:]",host);
redirector_ip = inet_addr(host);
if (redirector_ip == INADDR_NONE)
{
g_debug(_("host in the url is not an ipv4 address, will do async dns lookup"));
GResolver * dns = g_resolver_get_default();
g_resolver_lookup_by_name_async(dns,host,NULL,redirector_host_resove_by_dns,dns);
}
sprintf((char*) httphead, (char*) httphead_t, desturl, desturl);
}
static inline void init_thread_libnet()
{
if(!libnet)
{
static char buf[LIBNET_ERRBUF_SIZE];
libnet = libnet_init(LIBNET_RAW4, NULL, buf);
}
}
static gboolean http_redirector( pcap_process_thread_param * param, gpointer user_data)
{
/*******************************************************************
* here we use TCP
* when we recv a SYN=1,ACK=0 packet, we just send a syn=1,ack=1 packet
* that contains nothing
* then we push a packet taht contains
* HTTP/1.0 302 Found
* Location: http://192.168.0.1/
* connection:close
*
* please visit http://192.168.0.1
* and then we reset the connection
* ****************************************************************/
struct tcphdr * tcp_head;
struct udphdr * udp_head;
if(clientmgr_get_client_is_enable_by_mac(param->packet_linklayer_hdr+6))
{
//继续交给后续代码处理
return FALSE ;
}
//非 enable 的客户端，现在要开始这般处理了,重定向到 ... 嘿嘿
struct iphdr * ip_head = (typeof(ip_head))(param->packet_ip_contents);
if (ip_head->daddr == redirector_ip)
{
return TRUE;
}
if (ip_head->saddr == redirector_ip)
{
return TRUE;
}
//如果是在 white list ....
if (whiteip && g_list_find(whiteip, GINT_TO_POINTER(ip_head->daddr)))
return FALSE;
if (whiteip && g_list_find(whiteip, GINT_TO_POINTER(ip_head->saddr)))
return FALSE;
// g_debug(_("thread %p is doing the redirect stuff"),g_thread_self());
//Retrive the tcp header and udp header
tcp_head = (struct tcphdr*) ((char*) ip_head + ip_head->ihl * 4);
udp_head = (struct udphdr*) ((char*) ip_head + ip_head->ihl * 4);
#ifdef DEBUG_ONLY_HTTP_PORT
if (tcp_head->dest != HTTP_PORT)
return TRUE;
#endif
//初始化libnet，每个线程一个 libnet ;)
init_thread_libnet();
// http 重定向
if(ip_head->protocol == IPPROTO_TCP && tcp_head->dest == HTTP_PORT)
{
u_int8_t tcp_flags = ((struct libnet_tcp_hdr *) tcp_head)->th_flags;
if(tcp_flags == TH_SYN)
{
/********************************
* 对于这样的一个握手数据包
* 我们应该要建立连接了
* 回复一个syn ack 就是了
*********************************/
// here we just echo ack and syn.
libnet_build_tcp(ntohs(tcp_head->dest), ntohs(tcp_head->source), tcp_head->seq, ntohl(
tcp_head->seq) + 1, TH_ACK | TH_SYN, 4096, 0, 0, 20, 0, 0,
libnet, 0);
libnet_build_ipv4(40, 0, 0, 0x4000, 63/*ttl*/, IPPROTO_TCP, 0,
ip_head->daddr, ip_head->saddr, 0, 0, libnet, 0);
libnet_write(libnet);
libnet_clear_packet(libnet);
libnet_build_tcp(ntohs(tcp_head->dest), ntohs(tcp_head->source), tcp_head->seq, ntohl(
tcp_head->seq) + 1, TH_ACK | TH_SYN, 4096, 0, 0, 20, 0, 0,
libnet, 0);
libnet_build_ipv4(40, 0, 0, 0x4000, 63/*ttl*/, IPPROTO_TCP, 0,
ip_head->daddr, ip_head->saddr, 0, 0, libnet, 0);
}else if (tcp_flags & (TH_ACK|TH_SYN) )
{
/*********************************************
*现在是发送页面的时候啦！
*********************************************/
int SIZEHTTPHEAD = strlen((const char*) httphead);
libnet_build_tcp(ntohs(tcp_head->dest), ntohs(tcp_head->source), ntohl(tcp_head->ack_seq),
ntohl(tcp_head->seq) + ntohs(ip_head->tot_len) - 40, TH_ACK
| TH_PUSH | TH_FIN, 4096, 0, 0, 20 + SIZEHTTPHEAD,
httphead, SIZEHTTPHEAD, libnet, 0);
libnet_build_ipv4(40 + SIZEHTTPHEAD, 0, 0, 0x4000, 63/*ttl*/,
IPPROTO_TCP, 0, ip_head->daddr, ip_head->saddr, 0, 0, libnet, 0);
}
else if (tcp_flags & (TH_FIN|TH_RST))
{
/*********************************************************
*好，现在结束连接！
********************************************************/
libnet_build_tcp(ntohs(tcp_head->dest), ntohs(tcp_head->source), ntohl(tcp_head->ack_seq),
ntohl(tcp_head->seq) + 1, TH_ACK|TH_RST, 4096, 0, 0, 20, 0, 0, libnet,
0);
libnet_build_ipv4(40, 0, 0, 0x4000, 63/*ttl*/, IPPROTO_TCP, 0,
ip_head->daddr, ip_head->saddr, 0, 0, libnet, 0);
printf("------------------------------------------------------------------------link disconnect\n");
}else{
return FALSE;
}
}//其他 TCP 直接 RST
else if( ip_head->protocol == IPPROTO_TCP)
{
libnet_build_tcp(ntohs(tcp_head->dest), ntohs(tcp_head->source), ntohl(tcp_head->ack_seq),
ntohl(tcp_head->seq) + 1, TH_ACK|TH_RST, 4096, 0, 0, 20, 0, 0, libnet,
0);
libnet_build_ipv4(40, 0, 0, 0x4000, 63/*ttl*/, IPPROTO_TCP, 0,
ip_head->daddr, ip_head->saddr, 0, 0, libnet, 0);
}else if(ip_head->protocol == IPPROTO_UDP && udp_head->dest != DNS_PORT)
{
//现在是 UDP 的时代了
libnet_build_udp(ntohs(udp_head->dest),ntohs(udp_head->source),
sizeof(blank)+sizeof(struct udphdr),0,blank,sizeof(blank),libnet,0);
libnet_build_ipv4(40, 0, 0, 0x4000, 63/*ttl*/, IPPROTO_UDP, 0,
ip_head->daddr, ip_head->saddr, 0, 0, libnet, 0);
}else
return FALSE;
// if(param->linklayer_len == 14)
// libnet_build_ethernet(
// ((struct libnet_ethernet_hdr *) param->packet_linklayer_hdr)->ether_shost,
// /((struct libnet_ethernet_hdr *) param->packet_linklayer_hdr)->ether_dhost,
// ETHERTYPE_IP, 0, 0, libnet, 0);
libnet_autobuild_ethernet(
((struct libnet_ethernet_hdr *) param->packet_linklayer_hdr)->ether_shost,
ETHERTYPE_IP,libnet
);
libnet_write(libnet);
libnet_clear_packet(libnet);
return TRUE;
}
G_MODULE_EXPORT gchar * g_module_check_init(GModule *module)
{
gboolean enable;
GError * err=NULL;
gchar * url;
enable = g_key_file_get_boolean(gkeyfile, GROUP_NAME,"enable",&err);
if(err)
{
enable = TRUE;
g_error_free(err);
g_message("%s","[http_redirect]:[enable] not specified, default to enable");
err = NULL;
}
if (!enable)
{
return "[http_redirect]:[enable=false], user disabled me";
}
url = g_key_file_get_string(gkeyfile, GROUP_NAME, "url", NULL);
if(!url)
{
return "[http_redirect]:[url] not defined, please define one";
}
http_redirector_init(url);
gchar * ips = g_key_file_get_string(gkeyfile,GROUP_NAME,"whitelist",&err);
if(err)
{
g_error_free(err);
}else
{
GResolver * dns = g_resolver_get_default();
void resove_host_by_dns(GObject *source_object, GAsyncResult *res,gpointer user_data)
{
GList * hosts = g_resolver_lookup_by_name_finish(G_RESOLVER(source_object),res,NULL);
if(hosts)
{
GList * it = g_list_first(hosts);
do
{
GInetAddress * addr = (GInetAddress*)(it->data);
if(g_inet_address_get_native_size(addr)==4)
{
in_addr_t ip;
memcpy(&ip,g_inet_address_to_bytes(addr),4);
whiteip = g_list_prepend(whiteip,GUINT_TO_POINTER(ip));
g_message(_("%s's DNS result : %s"),(char*)user_data,g_inet_address_to_string(addr));
}
}while(( it = g_list_next(it)));
g_resolver_free_addresses(hosts);
}
g_object_unref(source_object);
g_free(user_data);
}
gchar *ptr;
gchar * one_host =strtok_r(ips," \t",&ptr);
while( one_host )
{
in_addr_t ip = inet_addr(one_host);
if (ip == INADDR_NONE)
{
g_object_ref(dns);
g_debug(_("host %s is not an ipv4 address, will do async dns lookup"),one_host);
g_resolver_lookup_by_name_async(dns,one_host,NULL,resove_host_by_dns,g_strdup(one_host));
}else
{
whiteip = g_list_prepend(whiteip,GUINT_TO_POINTER(ip));
}
one_host = strtok_r(NULL," \t",&ptr);
}
g_object_unref(dns);
}
g_module_make_resident(module);
pcap_hander_register_prepend(http_redirector, 0, IPPROTO_TCP, libnet);
return NULL;
}
void redirector_host_resove_by_dns(GObject *source_object, GAsyncResult *res,gpointer user_data)
{
GList * hosts = g_resolver_lookup_by_name_finish(G_RESOLVER(source_object),res,NULL);
if(hosts)
{
GList * it = g_list_first(hosts);
do
{
GInetAddress * addr = (GInetAddress*)(it->data);
if(g_inet_address_get_native_size(addr)==4)
{
memcpy(&redirector_ip,g_inet_address_to_bytes(addr),4);
g_message(_("DNS result : %s"),g_inet_address_to_string(addr));
break;
}
}while(( it = g_list_next(it)));
g_resolver_free_addresses(hosts);
}
g_object_unref(source_object);
}