/*
 * websend - synthesize a Web retrieval header for a file, and send it
 *  and the file to stdout (eg, for use with nc -cmd).
 *
 * websend content-type file-name
 *
 * The file-name is assumed to already have any necessary processing
 *  (such as replacing \n with CRLF) performed.
 *
 * websend just synthesizes an HTTP header, including a Content-Length:
 *  header giving the file size, with a Content-Type: header holding
 *  the first argument, and spews it to stdout, followed by the file's
 *  contents.  It also supplies a Date: header giving the current time
 *  in UTC, and a Last-Modified: header bearing the mtime from the
 *  file.  The rest of the header is fixed:
 *
 *	HTTP/1.0 200 OK
 *	Server: websend/1.0
 */
#include <stdio.h>
#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <strings.h>
#include <sys/time.h>
#include <sys/stat.h>

extern const char *__progname;

static const char *content_type;
static const char *file_name;

static int fd;
static struct stat stb;

static void header(void)
{
 struct timeval tv;
 time_t tt;
 struct tm *tm;
 char buf[8192];

 printf("HTTP/1.0 200 OK\r\n");
 printf("Server: websend/1.0\r\n");
 gettimeofday(&tv,0);
 tt = tv.tv_sec;
 tm = gmtime(&tt);
 strftime(&buf[0],sizeof(buf),"%a, %e %b %Y %T GMT",tm);
 printf("Date: %s\r\n",&buf[0]);
 tt = stb.st_mtime;
 tm = gmtime(&tt);
 strftime(&buf[0],sizeof(buf),"%a, %e %b %Y %T GMT",tm);
 printf("Last-Modified: %s\r\n",&buf[0]);
 printf("Content-Type: %s\r\n",content_type);
 printf("Content-Length: %llu\r\n",(unsigned long long int)stb.st_size);
 printf("\r\n");
}

static void content(void)
{
 off_t left;
 int n;
 int r;
 int wleft;
 int w;
 char *bp;
 char buf[8192];

 left = stb.st_size;
 while (left > 0)
  { n = sizeof(buf);
    if (n > left) n = left;
    r = read(fd,&buf[0],n);
    if (r < 0)
     { fprintf(stderr,"%s: read from %s: %s\n",__progname,file_name,strerror(errno));
       exit(1);
     }
    if (r == 0)
     { fprintf(stderr,"%s: premature EOF on %s (%llu left)\n",__progname,file_name,(unsigned long long int)left);
       exit(1);
     }
    left -= r;
    wleft = r;
    bp = &buf[0];
    while (wleft > 0)
     { w = write(1,bp,wleft);
       if (w < 0)
	{ fprintf(stderr,"%s: write error on stdout: %s\n",__progname,strerror(errno));
	  exit(1);
	}
       if (w == 0)
	{ fprintf(stderr,"%s: zero write on stdout?\n",__progname);
	  exit(1);
	}
       wleft -= w;
       bp += w;
     }
  }
}

int main(int, char **);
int main(int ac, char **av)
{
 if (ac != 3)
  { fprintf(stderr,"Usage: %s content-type file-name\n",__progname);
    exit(1);
  }
 content_type = av[1];
 file_name = av[2];
 fd = open(file_name,O_RDONLY,0);
 if (fd < 0)
  { fprintf(stderr,"%s: %s: %s\n",__progname,file_name,strerror(errno));
    exit(1);
  }
 if (fstat(fd,&stb) < 0)
  { fprintf(stderr,"%s: fstat %s: %s\n",__progname,file_name,strerror(errno));
    exit(1);
  }
 header();
 fflush(stdout);
 content();
 exit(0);
}