/* sender for internet stream demo */

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <stdio.h>
#include <string.h>
#include <sys/stat.h>
#include <fcntl.h>

#define ENDPACKET "end"
#define MAXLINE 256


help_msg()
{
     printf("format: spr -[cdnr] url\n");
     printf("           Option: c save in cache file format\n");
     printf("           Option: d set debug mode\n");
     printf("           Option: n set the number of retrievals\n");
     printf("           Option: r set the byte range for retrieval\n");
}

getline(s, lim)
char s[];
int lim;
{
   int c, i;

   for (i=0; i<lim-1 && (c=getchar()) != EOF && c != '\n' ; ++i) 
      s[i] = c;
   if (c == '\n') {
      s[i]= c;
      i++;
   }
   s[i]= '\0';
   return(i);
}

parseUrl(url, hostfield, domain, port, uri) 
char *url;
char *hostfield;
char *domain;
char *port;
char *uri;
{
   char *p, *p1;

	p = strstr(url, "//");
	p++; p++;
	p1 = strstr(p, "/");
	strncpy(hostfield, p, p1-p);
	hostfield[p1-p]='\0';
	strcpy(uri, p1);
	p= strstr(hostfield, ":");
   if (p!=NULL) {
	   strncpy(domain, hostfield, p-hostfield);
	   domain[p-hostfield]='\0';
	   strcpy(port, ++p);
	} else {
		strcpy(domain, hostfield);
	   strcpy(port, "80");  // default port
	}
	printf("url=%s\nhostfield=%s\ndomain=%s\nport=%s\nuri=%s\n", 
	       url, hostfield, domain, port, uri);

}

char *crange_header = "Content-Range: bytes ";

char *
getDataSize(fromBuf, fileLength)
char *fromBuf;
int *fileLength;
{
   char *p, *p1, *p2;
	char *dataPtr;
	char length[12];

	p = strstr(fromBuf, crange_header);
	if (p == NULL) {
	   printf("no content-range field\n"); exit(2);
	}
	p += strlen(crange_header);
   p1 = strstr(p, "/");
	if (p1 == NULL) {
	   printf("no / delimiter\n"); exit(3);
	}
	p1++;
	p2 = strstr(p1, "\r\n");
	strncpy(length, p1, p2-p1);
	length[p2-p1] = '\0';
	*fileLength=atoi(length);
	dataPtr = strstr(p2, "\r\n\r\n");
	dataPtr += 4;
	return dataPtr;
}
   

getByteRange(byteRange, startByte, endByte)
char *byteRange; 
int *startByte;
int *endByte;
{
   char *p;
	char sb[12];

	p = strstr(byteRange, "-");
	if (p == NULL) {
	   printf("byteRange=%s contains no '-'\n", byteRange); exit(3);
	}
	strncpy(sb, byteRange, p-byteRange);
	sb[p-byteRange]='\0';
	*startByte = atoi(sb);
	*endByte = atoi(++p);
}

main(argc, argv)
int argc;
char *argv[];
{
   int sock; 
   struct sockaddr_in server;
   struct hostent *hp, *gethostbyname();

   int n = 1;
   int i = 1;
   int nBytesRcvd;
   char toBuf[8192];
   char fromBuf[8192];
   extern char *optarg;
   extern int   optind;
   int option_exist = 0;
   int c;
   int debug = 0;
   char *rcv_name;  /* receiver's socket name */
	char *url;
	char hostfield[256];
	char domainname[256];
	char port[8];
	char uri[256];
	char byteRange[30];
	int startByte, endByte;
	int size;
   int port_no;
	char *dataPtr;
	char request[500];
	int length;
	int header_length;
	int fileLength;
	int fd;
	int cache = 0;  // cache flag =1 if file for cache server =0 for client
   char *outFile = "data.dat";

	 strcpy(byteRange, "1-400");
    /* process command line args */
    while ((c=getopt(argc,argv,"cdn:r:o:")) != EOF)
    {
        option_exist = 1;
        switch(c) {
        case 'c':
           cache = 1;
           printf("turn on saving cache file format mode.\n");
           break;
        case 'd':
           debug = 1;
           if (debug)
              printf("turn on debug mode.\n");
           break;
        case 'n':
           if ((n = atoi(optarg)) < 1) n = 1;
           if (debug)
              printf("The number of msgs sent is set to %d\n", n);
           break;
        case 'o':
           outFile = optarg;
           if (debug)
              printf("The datafile is set to %s\n", outFile);
           break;
        case 'r':
           strcpy(byteRange, optarg);
           if (debug)
              printf("The byte range is set to %s\n", byteRange);
           break;
        case '?':
           help_msg();
           exit (1);
        default:
            fprintf (stderr, "unrecognized arg >%s<\n", optarg);
            help_msg();
            exit (1);
        }
    }

   url = (char *) argv[optind++];
	printf("url=%s\n", url);
	parseUrl(url, hostfield, domainname, port, uri);
	printf("url=%s\nhostfield=%s\ndomainname=%s\nport=%s\nuri=%s\n", 
	       url, hostfield, domainname, port, uri);

   if (debug) 
      printf("The web server's host name is %s, port_no=%s\n", 
            domainname, port);

   /* create socket on which to sent */
   sock = socket(AF_INET, SOCK_STREAM, 0);
   if (sock < 0) {
      perror("opening stream socket");
      exit(1);
   }
   /* construct name of the socket to send to 
    * gethostbyname() returns a structure including the network address
    * of the specified host from /etc/hosts. The port number is taken from
    * the cmd line
    * create name structure for the internet socket 
    * use the name from cmd argument 
    */
   hp = gethostbyname(domainname);
   if (hp == 0) {
      fprintf(stderr, "%s: unknown host",rcv_name);
      exit(2);
   }
   memcpy(&server.sin_addr, hp->h_addr, hp->h_length);
   server.sin_family = AF_INET;
   server.sin_port = htons(atoi(port));

   if (connect(sock, &server, sizeof(server)) < 0) {
      perror("connecting stream socket");
      exit(1);
   }
	/* formulate request */
   sprintf(request, "GET %s HTTP/1.1\nRange: bytes=%s\nHost: %s\n\n",
	   uri, byteRange, hostfield);
	length = strlen(request);
	/* create data file */
	fd= open(outFile, O_WRONLY | O_CREAT, 00644);
	getByteRange(byteRange, &startByte, &endByte);
	if (debug) printf("startByte=%d, endByte=%d\n", startByte, endByte);
	size = endByte - startByte + 1;
   /*send message */
      if (write(sock, request, length) < 0) 
         perror("writing on stream socket");
      if ((nBytesRcvd=read(sock, fromBuf, sizeof(fromBuf))) < 0) {
         perror("reading on stream socket");
         exit(1);
      } 
		dataPtr = getDataSize(fromBuf, &fileLength);
		header_length = dataPtr - fromBuf;
		length = nBytesRcvd - header_length;
		printf("nBytesRcvd=%d, http  header length=%d\n", 
			       nBytesRcvd, header_length);
		if (debug) 
		   printf("fileLength=%d\n", fileLength);
	   if (cache) {
		   write(fd, fromBuf, nBytesRcvd);
		} else { 
		   write(fd, dataPtr, length);
		}
		if (debug) 
		   printf("packet %d: size=%d\n", i++, nBytesRcvd);
			
		size -= length;
		while(size>0)  {
			// more packets coming 
         if ((nBytesRcvd=read(sock, fromBuf, sizeof(fromBuf))) < 0) {
            perror("reading on stream socket");
            exit(1);
         } 
         if (nBytesRcvd == 0) { 
            printf("receiver breaks the connection, exiting...\n");
            break;
         }
	      write(fd, fromBuf, nBytesRcvd);
			if (debug) printf("packet %d: with %d bytes\n", i++,  nBytesRcvd);
			size -= nBytesRcvd;
      } 
	close(fd);
   close(sock);
}