#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/wait.h>
#include <signal.h>
#define MYPORT 80
#define BACKLOG 10
void sigchld_handler(int s)
{
while(wait(NULL) >0)
}
int main(void)
{
int sockfd, new_fd
struct sockaddr_in my_addr
struct sockaddr_in their_addr
int sin_size
struct sigaction sa
int yes=1
if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
perror("socket")
exit(1)
}
if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(int)) == -1) {
perror("setsockopt")
exit(1)
}
my_addr.sin_family = AF_INET
my_addr.sin_port = htons(MYPORT)
my_addr.sin_addr.s_addr = INADDR_ANY
memset(&(my_addr.sin_zero), '\0', 8 )
if (bind(sockfd, (struct sockaddr *)&my_addr, sizeof(struct sockaddr)) == -1) {
perror("bind")
exit(1)
}
if (listen(sockfd, BACKLOG) == -1) {
perror("listen")
exit(1)
}
sigemptyset(&sa.sa_mask)
sa.sa_flags = SA_RESTART
if (sigaction(SIGCHLD, &sa, NULL) == -1) {
perror("sigaction")
exit(1)
}
while(1) { // main accept() loop
sin_size = sizeof(struct sockaddr_in)
if ((new_fd = accept(sockfd, (struct sockaddr *)&their_addr, &sin_size)) == -1) {
perror("accept")
continue
}
printf("server: got connection from %s\n",inet_ntoa(their_addr.sin_addr))
if (!fork()) { // this is the child process
close(sockfd)// child doesn't need the listener
if (send(new_fd, "Hello, world!\n", 14, 0) == -1)
perror("send")
close(new_fd)
exit(0)
}
close(new_fd)
}
return 0
}
实现步骤：1）用Wireshark软件抓包得到test.pcap文件
2）程序：分析pcap文件头 ->分析pcap_pkt头 ->分析帧头 ->分析ip头 ->分析tcp头 ->分析http信息
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<netinet/in.h>
#include<time.h>
#define BUFSIZE 10240
#define STRSIZE 1024
typedef long bpf_int32
typedef unsigned long bpf_u_int32
typedef unsigned short u_short
typedef unsigned long u_int32
typedef unsigned short u_int16
typedef unsigned char u_int8
//pacp文件头结构体
struct pcap_file_header
{
bpf_u_int32 magic /* 0xa1b2c3d4 */
u_short version_major /* magjor Version 2 */
u_short version_minor /* magjor Version 4 */
bpf_int32 thiszone /* gmt to local correction */
bpf_u_int32 sigfigs/* accuracy of timestamps */
bpf_u_int32 snaplen/* max length saved portion of each pkt */
bpf_u_int32 linktype /* data link type (LINKTYPE_*) */
}
//时间戳
struct time_val
{
long tv_sec/* seconds 含义同 time_t 对象的值 */
long tv_usec /* and microseconds */
}
//pcap数据包头结构体
struct pcap_pkthdr
{
struct time_val ts /* time stamp */
bpf_u_int32 caplen/* length of portion present */
bpf_u_int32 len /* length this packet (off wire) */
}
//数据帧头
typedef struct FramHeader_t
{ //Pcap捕获的数据帧头
u_int8 DstMAC[6] //目的MAC地址
u_int8 SrcMAC[6] //源MAC地址
u_short FrameType //帧类型
} FramHeader_t
//IP数据报头
typedef struct IPHeader_t
{ //IP数据报头
u_int8 Ver_HLen //版本+报头长度
u_int8 TOS //服务类型
u_int16 TotalLen //总长度
u_int16 ID //标识
u_int16 Flag_Segment //标志+片偏移
u_int8 TTL //生存周期
u_int8 Protocol //协议类型
u_int16 Checksum //头部校验和
u_int32 SrcIP //源IP地址
u_int32 DstIP //目的IP地址
} IPHeader_t
//TCP数据报头
typedef struct TCPHeader_t
{ //TCP数据报头
u_int16 SrcPort //源端口
u_int16 DstPort //目的端口
u_int32 SeqNO //序号
u_int32 AckNO //确认号
u_int8 HeaderLen //数据报头的长度(4 bit) + 保留(4 bit)
u_int8 Flags //标识TCP不同的控制消息
u_int16 Window //窗口大小
u_int16 Checksum //校验和
u_int16 UrgentPointer //紧急指针
}TCPHeader_t
//
void match_http(FILE *fp, char *head_str, char *tail_str, char *buf, int total_len) //查找 http 信息函数
//
int main()
{
struct pcap_file_header *file_header
struct pcap_pkthdr *ptk_header
IPHeader_t *ip_header
TCPHeader_t *tcp_header
FILE *fp, *output
int pkt_offset, i=0
int ip_len, http_len, ip_proto
int src_port, dst_port, tcp_flags
char buf[BUFSIZE], my_time[STRSIZE]
char src_ip[STRSIZE], dst_ip[STRSIZE]
char host[STRSIZE], uri[BUFSIZE]
//初始化
file_header = (struct pcap_file_header *)malloc(sizeof(struct pcap_file_header))
ptk_header = (struct pcap_pkthdr *)malloc(sizeof(struct pcap_pkthdr))
ip_header = (IPHeader_t *)malloc(sizeof(IPHeader_t))
tcp_header = (TCPHeader_t *)malloc(sizeof(TCPHeader_t))
memset(buf, 0, sizeof(buf))
//
if((fp = fopen(“test.pcap”,”r”)) == NULL)
{
printf(“error: can not open pcap file\n”)
exit(0)
}
if((output = fopen(“output.txt”,”w+”)) == NULL)
{
printf(“error: can not open output file\n”)
exit(0)
}
//开始读数据包
pkt_offset = 24 //pcap文件头结构 24个字节
while(fseek(fp, pkt_offset, SEEK_SET) == 0) //遍历数据包
{
i++
//pcap_pkt_header 16 byte
if(fread(ptk_header, 16, 1, fp) != 1) //读pcap数据包头结构
{
printf(“\nread end of pcap file\n”)
break
}
pkt_offset += 16 + ptk_header->caplen //下一个数据包的偏移值
strftime(my_time, sizeof(my_time), “%Y-%m-%d %T”, localtime(&(ptk_header->ts.tv_sec))) //获取时间
// printf(“%d: %s\n”, i, my_time)
//数据帧头 14字节
fseek(fp, 14, SEEK_CUR) //忽略数据帧头
//IP数据报头 20字节
if(fread(ip_header, sizeof(IPHeader_t), 1, fp) != 1)
{
printf(“%d: can not read ip_header\n”, i)
break
}
inet_ntop(AF_INET, (void *)&(ip_header->SrcIP), src_ip, 16)
inet_ntop(AF_INET, (void *)&(ip_header->DstIP), dst_ip, 16)
ip_proto = ip_header->Protocol
ip_len = ip_header->TotalLen //IP数据报总长度
// printf(“%d: src=%s\n”, i, src_ip)
if(ip_proto != 0×06) //判断是否是 TCP 协议
{
continue
}
//TCP头 20字节
if(fread(tcp_header, sizeof(TCPHeader_t), 1, fp) != 1)
{
printf(“%d: can not read ip_header\n”, i)
break
}
src_port = ntohs(tcp_header->SrcPort)
dst_port = ntohs(tcp_header->DstPort)
tcp_flags = tcp_header->Flags
// printf(“%d: src=%x\n”, i, tcp_flags)
if(tcp_flags == 0×18) // (PSH, ACK) 3路握手成功后
{
if(dst_port == 80) // HTTP GET请求
{
http_len = ip_len – 40 //http 报文长度
match_http(fp, “Host: “, “\r\n”, host, http_len) //查找 host 值
match_http(fp, “GET “, “HTTP”, uri, http_len) //查找 uri 值
sprintf(buf, “%d: %s src=%s:%d dst=%s:%d %s%s\r\n”, i, my_time, src_ip, src_port, dst_ip, dst_port, host, uri)
//printf(“%s”, buf)
if(fwrite(buf, strlen(buf), 1, output) != 1)
{
printf(“output file can not write”)
break
}
}
}
} // end while
fclose(fp)
fclose(output)
return 0
}
//查找 HTTP 信息
void match_http(FILE *fp, char *head_str, char *tail_str, char *buf, int total_len)
{
int i
int http_offset
int head_len, tail_len, val_len
char head_tmp[STRSIZE], tail_tmp[STRSIZE]
//初始化
memset(head_tmp, 0, sizeof(head_tmp))
memset(tail_tmp, 0, sizeof(tail_tmp))
head_len = strlen(head_str)
tail_len = strlen(tail_str)
//查找 head_str
http_offset = ftell(fp) //记录下HTTP报文初始文件偏移
while((head_tmp[0] = fgetc(fp)) != EOF) //逐个字节遍历
{
if((ftell(fp) – http_offset) >total_len) //遍历完成
{
sprintf(buf, “can not find %s \r\n”, head_str)
exit(0)
}
if(head_tmp[0] == *head_str) //匹配到第一个字符
{
for(i=1i<head_leni++) //匹配 head_str 的其他字符
{
head_tmp[i]=fgetc(fp)
if(head_tmp[i] != *(head_str+i))
break
}
if(i == head_len) //匹配 head_str 成功，停止遍历
break
}
}
// printf(“head_tmp=%s \n”, head_tmp)
//查找 tail_str
val_len = 0
while((tail_tmp[0] = fgetc(fp)) != EOF) //遍历
{
if((ftell(fp) – http_offset) >total_len) //遍历完成
{
sprintf(buf, “can not find %s \r\n”, tail_str)
exit(0)
}
buf[val_len++] = tail_tmp[0] //用buf 存储 value 直到查找到 tail_str
if(tail_tmp[0] == *tail_str) //匹配到第一个字符
{
for(i=1i<tail_leni++) //匹配 head_str 的其他字符
{
tail_tmp[i]=fgetc(fp)
if(tail_tmp[i] != *(tail_str+i))
break
}
if(i == tail_len) //匹配 head_str 成功，停止遍历
{
buf[val_len-1] = 0 //清除多余的一个字符
break
}
}
}
// printf(“val=%s\n”, buf)
fseek(fp, http_offset, SEEK_SET) //将文件指针 回到初始偏移
}
用来分离处理状态行，另外六个头部行和返回数据的函数HTTP/1.1 200 OK
Date: Mon, 12 Mar 2004 19:12:16 GMT
Server: Apache/1.3.31 (Unix) mod_throttle/3.1.2
Last-Modified: Fri, 22 Sep 2004 14:16:18
ETag: "dd7b6e-d29-39cb69b2"
Accept-Ranges: bytes
Content-Length: 3369
Connection: close
Content-Type: text/html
File content goes here
也就是根据上面这些内容的字符串data，调用一个函数比如state(data)能返回200，content(data)返回指向file content的字符串
望采纳，谢谢
