/*************************************************************************//*                                                                       *//*                  Language Technologies Institute                      *//*                     Carnegie Mellon University                        *//*                         Copyright (c) 2011                            *//*                        All Rights Reserved.                           *//*                                                                       *//*  Permission is hereby granted, free of charge, to use and distribute  *//*  this software and its documentation without restriction, including   *//*  without limitation the rights to use, copy, modify, merge, publish,  *//*  distribute, sublicense, and/or sell copies of this work, and to      *//*  permit persons to whom this work is furnished to do so, subject to   *//*  the following conditions:                                            *//*   1. The code must retain the above copyright notice, this list of    *//*      conditions and the following disclaimer.                         *//*   2. Any modifications must be clearly marked as such.                *//*   3. Original authors' names are not deleted.                         *//*   4. The authors' names are not used to endorse or promote products   *//*      derived from this software without specific prior written        *//*      permission.                                                      *//*                                                                       *//*  CARNEGIE MELLON UNIVERSITY AND THE CONTRIBUTORS TO THIS WORK         *//*  DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING      *//*  ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT   *//*  SHALL CARNEGIE MELLON UNIVERSITY NOR THE CONTRIBUTORS BE LIABLE      *//*  FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES    *//*  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN   *//*  AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,          *//*  ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF       *//*  THIS SOFTWARE.                                                       *//*                                                                       *//*************************************************************************//*             Author:  Alan W Black (awb@cs.cmu.edu)                    *//*               Date:  November 2011                                    *//*************************************************************************//*                                                                       *//*  Support to access (some forms of) url                                *//*      http:  and file:                                                 *//*  Should support libcurl if available -- but a simple form if not      *//*                                                                       *//*  Only support http: if sockets are available                          *//*                                                                       *//*************************************************************************/#include "cst_math.h"#include "cst_file.h"#include "cst_string.h"#include "cst_tokenstream.h"#include "cst_socket.h" #ifndef CST_NO_SOCKETS#ifndef _MSC_VER#include <stdlib.h>#include <unistd.h>#else#include <io.h>#include <WinSock.h>#endif#endif int cst_urlp(const char *url){    /* Return 1 if url is a url, 0 otherwise */    /* This is decided by the initial substring being "http:" or "file:" */    if ((cst_strlen(url) > 4) &&        (cst_streqn("http:",url,5) ||         cst_streqn("file:",url,5)))        return TRUE;    else        return FALSE;} cst_file cst_url_open(const char *url){    /* Always opens it for reading */    cst_tokenstream *urlts;    const cst_string *protocol;    int port;    cst_string *host;    int fd;    char *url_request;    char *path;    cst_file ofd;    int state,n;    char c;     urlts = ts_open_string(url, "", ":/", "", "");     protocol = ts_get(urlts);    if (cst_streq(protocol,"http"))    {#ifdef CST_NO_SOCKETS        ts_close(urlts);        return NULL;#else        if (!cst_streq(ts_get(urlts),":") ||            !cst_streq(ts_get(urlts),"/") ||            !cst_streq(ts_get(urlts),"/"))        {            ts_close(urlts);            return NULL;        }        host = cst_strdup(ts_get(urlts));        if (cst_streq(ts_get(urlts),":"))            port = (int)cst_atof(ts_get(urlts));        else            port = 80;         /* Open port to web server */        fd = cst_socket_open(host,port);        if (fd < 0)        {            cst_free(host);            ts_close(urlts);            return NULL;        }         url_request = cst_alloc(char,cst_strlen(url)+17);        cst_sprintf(url_request,"GET %s HTTP/1.2\n\n",url);        n = write(fd,url_request,cst_strlen(url_request));        cst_free(url_request);         /* Skip http header -- until \n\n */        state=0;        while (state != 4)        {            n=read(fd,&c,1);            if (n == 0)            {   /* eof or link gone down */                cst_free(host);                ts_close(urlts);                return NULL;            }            if ((state == 0) && (c == '\r'))                state=1;            else if ((state == 1) && (c == '\n'))                state=2;            else if ((state == 2) && (c == '\r'))                state=3;            else if ((state == 3) && (c == '\n'))                state=4;            /* Not sure you can get no CRs in the stream */            else if ((state == 0) && (c == '\n'))                state=2;            else if ((state == 2) && (c == '\n'))                state=4;            else                state = 0;        }         ofd = fdopen(fd,"rb");         ts_close(urlts);        cst_free(host);         return ofd;#endif    }    else if (cst_streq(protocol,"file"))    {        if (!cst_streq(ts_get(urlts),":") ||            !cst_streq(ts_get(urlts),"/") ||            !cst_streq(ts_get(urlts),"/"))        {            ts_close(urlts);            return NULL;        }        path = cst_strdup(&urlts->string_buffer[urlts->file_pos-1]);        /* printf("awb_debug fileurl %s\n",path); */         ofd = cst_fopen(path,CST_OPEN_READ);         ts_close(urlts);        cst_free(path);                return ofd;    }    else    {   /* Unsupported protocol */        return NULL;    }}