解析http302重定向url

bool urlparse(const u_char* data,u_int len)

{

ip_header *ih;

udp_header *uh;

tcp_header *th;

u_short sport,dport;

int ip_len = 0;

ih = (ip_header *)(data+0xE);

ip_len = (ih->ver_ihl & 0xf) * sizeof(unsigned long);

th = (tcp_header *) ((u_char*)ih + ip_len);

sport = ntohs( th->th_sport );

dport = ntohs( th->th_dport );

if ((ih->proto != IPPROTO_TCP))

return false;

std::string strdata((char*)th + sizeof(tcp_header),len - ip_len - sizeof(tcp_header)+1);

static char szTag0[] = "HTTP/1.1 302 Moved Temporarily\r\n";

static char szTag1[] = "Location: ";

static char szTag2[] = "\r\n\r\n";

size_t nP0 = strdata.find(szTag0);

if (nP0 == std::string::npos)

return false;

size_t nP1 = strdata.find(szTag1,nP0+strlen(szTag0));

if (nP1 == std::string::npos)

return false;

size_t nP2 = strdata.find(szTag2,nP1+strlen(szTag1));

if (nP2 == std::string::npos)

return false;

std::string strUrl = strdata.substr(nP1+strlen(szTag1),nP2-nP1-strlen(szTag1));

printf("url>%s\n",strUrl.c_str());

return true;

}