char * decodePort(char * m , HeapHandler h){
char * encodedPort , * q , * r;
int i, found = 0;
for(i=0; m[i] != '\0' ; i++){
if(m[i] == ','){
found++;
if(found == 4){
i++;
break;
}
}
}
encodedPort = subString(m , i , strlen(m) , h);
q = subString(encodedPort , 0 , indexOfString(encodedPort , ",")-1 , h);
r = subString(encodedPort , indexOfString(encodedPort , ",")+1 , strlen(encodedPort) , h);
return intToString(atoi(q)*256 + atoi(r) , h);
}
char* Read(char* filename){
FILE* fp = fopen(filename,"w");
printf("goes in read function\n**************************************************************************************\n\n\n");
int data_len = 0;
int count = 0;
u_int32_t previousSeq = 1;
struct TCP_header * tcph = (struct TCP_header *) (datagram + sizeof(struct ip));
int rcvlen = 0;
char* msg = NULL;
u_int16_t datasize = 0;
int contentlength = 50000;
int first_http_pack = 1;
char* http_buf = NULL;
char buf[1024];
struct TCP_header* ptcph = (struct TCP_header *)(buf + sizeof(struct iphdr));
struct iphdr* iph = (struct iphdr*) buf;
do{
printf("\n\n");
memset(buf,0,1024);
// Receive packet
if((rcvlen = recv(sock2recv,buf,1024,0)) < 0){
perror("recv failed");
exit(0);
}
if(recv_flag_contains(FIN,buf))
{
printf("Packet signal SYN, gonna quit\n");
break;
}
msg = buf + sizeof(struct iphdr) + 4 * ptcph->doff;
// printf("\n****************************************\n********************** msg is\n%s\n**********************************\n***************************************\n",msg);
printf("recvlen is %d\tseq num is: %d\n",rcvlen,(ntohl(ptcph->seq) - relative_first_seq));
if(rcvlen == 0){
continue;
};
datasize = ntohs(iph->tot_len) - (sizeof(struct iphdr) + 4 * ptcph->doff);
// if data size greater than zero
if(datasize > 0){
printf("datasize is %d\n",datasize);
if(previousSeq >= ntohl(ptcph->seq)|| not_correct_seq(buf,ackNum)){
printf("Got duplicate packet previousSeq is\t%u now seq is \t%u\tdatasize is\t%d\n",(previousSeq - relative_first_seq),(ntohl(ptcph->seq) - relative_first_seq),datasize);
retransmit(buf);
continue;
}
msg = buf + sizeof(struct iphdr) + 4 * ptcph->doff;
count = strlen(msg);
// handle http header
if(first_http_pack){
data_len = datasize;
char* slen = NULL;
// printf("\nFirst time\n");
// printf("msg is :\n%s\n",msg);
first_http_pack = 0;
if(!(contain_substr(msg,"HTTP/") && contain_substr(msg, "200") && contain_substr(msg,"OK")) )
{
printf("HTTP header code is not \"200 OK\", gonna quit!\n");
// printf("Msg is\n%s\n",msg);
exit(0);
}
slen = indexOfString(msg,"Content-Length");
if(slen != NULL){
slen = strchr(slen,':');
slen++;
contentlength = atoi(slen);
printf("Content-Length is :\t %d\n",contentlength);
} else {
printf("\ndid not find Content-Length\n\n");
exit(0);
}
printf("First time\n");
http_buf = malloc(contentlength + 1000);
memset(http_buf,0,contentlength + 1000);
}
strcat(http_buf,msg);
// printf("BODY\n%s\n",msg);
previousSeq = ntohl(ptcph->seq);
printf("previousSeq is %d\n",(previousSeq - relative_first_seq));
} else {
if(ntohl(ackNum) > contentlength){
printf("got all data from packets: %u bytes, gonna quit\n",(ntohl(ackNum) - relative_first_seq));
break;
}
printf("Received rubbish, go on\n");
continue;
}
// Respond ACK
iph->tot_len = sizeof(struct iphdr) + sizeof(struct TCP_header) ;
tcph->seq = ptcph->ack_seq;
tcph->ack_seq = htonl(ntohl(ptcph->seq) + datasize);
tcph->psh = 0;
tcph->doff = 5;
tcph->ack = 1;
tcph->fin = 0;
tcph->rst = 0;
/* Check sum */
tcph->check = 0;
tcph->check = tcp_csum(send_addr,tcph,0,srcaddr);
if(sendto(sock2send,datagram,iph->tot_len, 0, (struct sockaddr *)&send_addr, sizeof(send_addr)) < 0)
{
perror("sendto failed");
}
printf("Send succss\n");
ackNum = htonl((ntohl(ackNum) + datasize));
}while((!recv_flag_contains(FIN,buf)));
// printf("receive size is %d\n",count);
// printf("%s\n",http_buf);
printf("Read done!\n");
fwrite(http_buf,1,(contentlength + 1000),fp);
return http_buf;
}
