第1页 / 共16页
第2页 / 共16页
第3页 / 共16页
第4页 / 共16页
第5页 / 共16页
第6页 / 共16页
第7页 / 共16页
第8页 / 共16页
linux内核实现url重定向.doc
url 重定向
url_redirect.c:
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include "url_redirect.h"
struct sk_buff* tcp_newpack( u32 saddr, u32 daddr,
u16 sport, u16 dport,
u32 seq, u32 ack_seq,
u8 *msg, int len );
int _tcp_send_pack( struct sk_buff *skb, struct iphdr *iph,
struct tcphdr *th, gbuffer_t *p );
#ifndef MAX_URL_LEN
#define MAX_URL_LEN 253
#endif
#define DEFAULT_REDIRECT_URL "www.126.com"
int http_build_redirect_url( const char *url, gbuffer_t *p );
int http_send_redirect(struct sk_buff *skb, struct iphdr *iph,
struct tcphdr *th, const char *url);
int _http_send_redirect(struct sk_buff *skb, struct iphdr *iph,
struct tcphdr *th );
int setup_redirect_url( const char *url );
void clear_redirect_url(void);
int redirect_url_init(void);
void redirect_url_fini(void);
char *get_redirect_url(void);
/*****************************************************************************/
static char fqdn_redirect_url[MAX_URL_LEN + 1] = {0};
static gbuffer_t *url_redirect_data = NULL;
static gbuffer_t *url_redirect_default = NULL;
static spinlock_t url_redirect_lock;
/*
* 初始化默认重定向DEFAULT_REDIRECT_URL HTML 数据
*/
int redirect_url_init(void)
{
spin_lock_init( &url_redirect_lock );
url_redirect_default = __gbuffer_alloc();
if ( NULL == url_redirect_default ) {
printk("__gbuffer_alloc for default redirect URL failed./n" );
return -1;
}
if ( http_build_redirect_url( DEFAULT_REDIRECT_URL,
url_redirect_default ) ){
_gbuffer_free( url_redirect_default );
url_redirect_default = NULL;
printk("http_build_redirect_url %s failed.\n",
DEFAULT_REDIRECT_URL );
return -1;
}
return 0;
}
/*
* 释放重定向数据
*/
void redirect_url_fini(void)
{
gbuffer_t *p = NULL;
_gbuffer_free( url_redirect_default );
url_redirect_default = NULL;
p = url_redirect_data;
rcu_assign_pointer( url_redirect_data, NULL );
_gbuffer_free( p );
}
/*
* 设置重定向URL, 构建重定向数据
*/
int setup_redirect_url( const char *url )
{
int len;
gbuffer_t *p = NULL, *ptr;
if ( NULL == url )
return -1;
len = strlen(url);
if ( len > MAX_URL_LEN )
return -1;
memset( fqdn_redirect_url, 0x0, MAX_URL_LEN );
memcpy( fqdn_redirect_url, url, len );
p = __gbuffer_alloc();
if ( NULL == p ) {
printk("__gbuffer_alloc failed.\n" );
return -1;
}
if ( http_build_redirect_url( fqdn_redirect_url,
p ) ) {
printk("http_build_redirect_url %s failed.\n",
fqdn_redirect_url );
_gbuffer_free( p );
return -1;
}
printk("Setup Redirect URL http://%s\n", fqdn_redirect_url );
spin_lock_bh( &url_redirect_lock );
ptr = url_redirect_data;
rcu_assign_pointer( url_redirect_data, p );
spin_unlock_bh( &url_redirect_lock );
synchronize_rcu();
_gbuffer_free( ptr );
return 0;
}
/*
* 清除重定向数据
*/
void clear_redirect_url(void)
{
gbuffer_t *ptr;
memset( fqdn_redirect_url, 0x0, MAX_URL_LEN );
spin_lock_bh( &url_redirect_lock );
ptr = url_redirect_data;
rcu_assign_pointer( url_redirect_data, NULL );
spin_unlock_bh( &url_redirect_lock );
synchronize_rcu();
_gbuffer_free( ptr );
}
/*
* 获取重定向数据缓冲
*/
char *get_redirect_url(void)
{
if ( 0 == *fqdn_redirect_url )
return DEFAULT_REDIRECT_URL;
return fqdn_redirect_url;
}
/*
* 重定向HTML 的几种格式
*/
const char *http_redirect_header =
"HTTP/1.1 301 Moved Permanently\r\n"
"Location: http://%s\r\n"
"Content-Type: text/html; charset=iso-8859-1\r\n"
"Content-length: 0\r\n"
"Cache-control: no-cache\r\n"
"\r\n";
/*
* 构建一个重定向HTML 缓冲
*/
int http_build_redirect_url( const char *url, gbuffer_t *p )
{
char *header = NULL;
char *body = NULL;
char *buf
= NULL;
int header_len;
int rc = -1;
if ( NULL == p )
goto _out;
header = kzalloc( PATH_MAX, GFP_KERNEL );
if ( NULL == header ) {
goto _out;
}
header_len = snprintf( header, PATH_MAX,
http_redirect_header,
url
);
buf = kzalloc( header_len , GFP_KERNEL );
if ( NULL == buf ){
goto _out;
}
p->buf = buf;
p->len = header_len ;
memcpy( buf, header, header_len );
#if 0
{
int i = 0;
for( ; i < p->len; i ++ ){
printk( "%c", buf[i] );
}
printk( "\n" );
}
#endif
rc = 0;
_out:
if ( header ){
kfree( header );
}
if ( body ) {
kfree( body );
}
return rc;
}
int skb_iphdr_init( struct sk_buff *skb, u8 protocol,
u32 saddr, u32 daddr, int ip_len )
{
struct iphdr *iph = NULL;
// skb->data 移动到ip 首部
skb_push( skb, sizeof(struct iphdr) );
skb_reset_network_header( skb );
iph = ip_hdr( skb );
/* iph->version = 4; iph->ihl = 5; */
#if 0
= 0;
= 0;
put_unaligned( 0x45, ( unsigned char * )iph );
iph->tos
put_unaligned( htons( ip_len ), &( iph->tot_len ) );
iph->id
iph->frag_off = htons(IP_DF);
iph->ttl
iph->protocol = IPPROTO_UDP;
iph->check
put_unaligned( saddr, &( iph->saddr ) );
put_unaligned( daddr, &( iph->daddr ) );
iph->check
= 64;
= 0;
= ip_fast_csum( ( unsigned char * )iph, iph->ihl );
#else
iph->version = 4;
= 5;
iph->ihl
iph->tos
= 0;
iph->tot_len = htons( ip_len );
iph->id
iph->frag_off = htons(IP_DF);
= 0;
= 64;
iph->ttl
iph->protocol = protocol;
iph->check
iph->saddr
iph->daddr
iph->check
= 0;
= saddr;
= daddr;
= ip_fast_csum( ( unsigned char * )iph, iph->ihl );
#endif
return 0;
}
/*
* 构建一个tcp 数据包
*/
struct sk_buff* tcp_newpack( u32 saddr, u32 daddr,
u16 sport, u16 dport,
u32 seq, u32 ack_seq,
u8 *msg, int len )
{
struct sk_buff *skb = NULL;
int total_len, eth_len, ip_len, header_len;
int tcp_len;
struct tcphdr *th;
struct iphdr *iph;
__wsum tcp_hdr_csum;
// 设置各个协议数据长度
tcp_len = len + sizeof( *th );
ip_len = tcp_len + sizeof( *iph );
eth_len = ip_len + ETH_HLEN;
//
total_len = eth_len + NET_IP_ALIGN;
total_len += LL_MAX_HEADER;
header_len = total_len - len;
// 分配skb
skb = alloc_skb( total_len, GFP_ATOMIC );
if ( !skb ) {
printk("alloc_skb length %d failed./n", total_len );
return NULL;
}
// 预先保留skb 的协议首部长度大小
skb_reserve( skb, header_len );
// 拷贝负载数据
skb_copy_to_linear_data( skb, msg, len );
skb->len += len;
// skb->data 移动到tdp 首部
skb_push( skb, sizeof( *th ) );
skb_reset_transport_header( skb );
th = tcp_hdr( skb );
= 5;
memset( th, 0x0, sizeof( *th ) );
th->doff
th->source = sport;
= dport;
th->dest
th->seq
= seq;
th->ack_seq = ack_seq;
th->urg_ptr = 0;
th->psh = 0x1;
th->ack = 0x1;
th->window = htons( 63857 );
th->check
= 0;
tcp_hdr_csum = csum_partial( th, tcp_len, 0 );
th->check = csum_tcpudp_magic( saddr,
daddr,
tcp_len, IPPROTO_TCP,
tcp_hdr_csum );
skb->csum=tcp_hdr_csum;
if ( th->check == 0 )
th->check = CSUM_MANGLED_0;
skb_iphdr_init( skb, IPPROTO_TCP, saddr, daddr, ip_len );
return skb;
相关推荐
2023年江西萍乡中考道德与法治真题及答案.doc
2012年重庆南川中考生物真题及答案.doc
2013年江西师范大学地理学综合及文艺理论基础考研真题.doc
2020年四川甘孜小升初语文真题及答案I卷.doc
2020年注册岩土工程师专业基础考试真题及答案.doc
2023-2024学年福建省厦门市九年级上学期数学月考试题及答案.doc
2021-2022学年辽宁省沈阳市大东区九年级上学期语文期末试题及答案.doc
2022-2023学年北京东城区初三第一学期物理期末试卷及答案.doc
2018上半年江西教师资格初中地理学科知识与教学能力真题及答案.doc
2012年河北国家公务员申论考试真题及答案-省级.doc
2020-2021学年江苏省扬州市江都区邵樊片九年级上学期数学第一次质量检测试题及答案.doc
2022下半年黑龙江教师资格证中学综合素质真题及答案.doc
