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webget.c

/*    Copyright (C) 1998 XIAO, Gang of Universite de Nice - Sophia Antipolis
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

 /* This is a small program used simply to fetch web pages.
  * No fancy functionalities such as link redirection or site sucking is
  * present.
  * Page fetched can only be sent to stdout. */

#include "../wims.h"
#include <netdb.h>
#include <sys/socket.h>
#include <netinet/in.h>

char *cheater1="User-Agent: WIMS-webget";
char *cheater2="Accept: image/gif, image/x-xbitmap, image/jpeg, image/pjpeg, image/png, */*\r\n\
Accept-Encoding: gzip\r\n\
Accept-Language: en, fr, it, de, es\r\n\
Accept-Charset: iso-8859-1,*,utf-8";
char pbuf[4096], tbuf[4096];
char tfname[1024];
char *tmpdir="/tmp";
int soc, port, https;
int charcnt;
FILE *outf;

void errorquit(char *msg)
{
    fprintf(stderr,"%s: %s\n",msg,strerror(errno)); exit(1);
}

      /* Points to the end of the word */
char *find_word_end(char *p)
{
    int i;
    for(i=0;!isspace(*p) && *p!=0 && i<MAX_LINELEN; p++,i++);
    return p;
}

      /* Strips leading spaces */
char *find_word_start(char *p)
{
    int i;
    for(i=0; isspace(*p) && i<MAX_LINELEN; p++,i++);
    return p;
}

      /* Secured execution */
void secure(char *host)
{
    char *p1, *p2, *p3, buf[MAX_LINELEN+1];
    long int l;
    FILE *f;

    p1=getenv("w_module"); if(p1==NULL || *p1==0) return;
    p1=getenv("untrust"); if(p1==NULL || *p1==0) return;
    f=fopen("webget.sites","r"); if(f==NULL) return;
    l=fread(buf,1,MAX_LINELEN,f); fclose(f);
    if(l<=0 || l>MAX_LINELEN) return;
    buf[l]=0;
    for(p1=find_word_start(buf);*p1;p1=find_word_start(p2)) {
      p2=find_word_end(p1); if(*p2) *p2++=0;
      p3=strstr(host,p1); if(p3==NULL) continue;
      if((p3==host || *(p3-1)=='.') && *(p3+strlen(p1))==0) return;
    }
    exit(1);  /* unauthorized sites refused. */
}

      /* open a TCP/IP socket with host/port
       * returns the file descriptor for the socket */
int net_connect(char *host)
{
    struct hostent *hp;
    struct sockaddr_in sin;
    int soc;

    secure(host);
    if(!(hp = gethostbyname(host))) errorquit("unknown host.");
    if((soc = socket(hp->h_addrtype,SOCK_STREAM,0))<0)
      errorquit("socket() error");
    memmove(&sin.sin_addr,hp->h_addr,hp->h_length);
    sin.sin_port=((port>>8)&0xff)|((port<<8)&0xff00);
    sin.sin_family = hp->h_addrtype;
    if(connect(soc,(struct sockaddr *)&sin,sizeof(sin))<0) {
      close(soc); errorquit("connect() error");
    }
    return soc;
}

int gethttps(char *host)
{
    char buf[65536];
    char *tp;
    
    tp=getenv("tmp_dir"); if(tp!=NULL && *tp!=0) tmpdir=tp;    
    snprintf(tfname,sizeof(tfname),"%s/https.tmp",tmpdir);
    snprintf(buf,sizeof(buf),"\
mkdir -p %s\n\
openssl s_client -connect %s:%d -quiet 2>/dev/null >%s <<@\n\
%s\n\
@\n", tmpdir,host,port,tfname,tbuf);
    system(buf);
    return open(tfname,O_RDONLY);
}

int main(int argc, char *argv[])
{
    char *parm, *p1, *p2, *p3, *p4, *dp;
    char nbuf[4096], *pp1, *pp2;
    char c;
    
    parm=getenv("wims_exec_parm");
    if(parm==NULL || *parm==0) errorquit("no_parameter");
    snprintf(pbuf,sizeof(pbuf),"%s",parm);
    p1=find_word_start(pbuf); p2=find_word_end(p1);
    if(*p2!=0) *p2++=0; https=0;
    dp=getenv("w_webget_option");
    if(dp!=NULL && strstr(dp,"direct")!=NULL) { /* direct get */
      p1=getenv("w_webget_host");
      p2=getenv("w_webget_port");
      if(p1==NULL || p2==NULL) errorquit("incomplete_request");
      port=atoi(p2);
      soc=net_connect(p1);
      c=' '; for(p3=parm; *p3; p3++) {
          if(*p3=='\n' && c!='\r') write(soc,"\r",1);
          write(soc,p3,1); c=*p3;
      }
      write(soc,"\r\n\r\n",4);
      charcnt=0; outf=stdout;
      while(read(soc,pbuf,1)>0 && charcnt<10240) {
          fputc(pbuf[0],outf); charcnt++;
      }
      close(soc);
      return 0;
    }
    if(strncasecmp(p1,"http://",strlen("http://"))==0) p1+=strlen("http://");
    else if(strncasecmp(p1,"https://",strlen("https://"))==0) {
      https=1; p1+=strlen("https://");
    }
    p3=strchr(p1,'/'); if(p3==NULL) p3="";
    else {*p3++=0; while(*p3=='/') p3++;}
    snprintf(tbuf,sizeof(tbuf),"GET /%s HTTP/1.0\r\n%s\r\n\
Host: %s\r\n\
%s\r\n\r\n",
           p3,cheater1,p1,cheater2);
    p4=strchr(p1,':'); if(p4==NULL) {
      if(https) port=443; else port=80;
    }
    else {*p4++=0; port=atoi(p4);}
    outf=stdout; pp1=getenv("w_webget_output");
    pp2=getenv("session_dir");
    if(pp1!=NULL && strstr(pp1,"..")==NULL && isalnum(*pp1) && pp2!=NULL) {
      snprintf(nbuf,sizeof(nbuf),"%s/%s",pp2,pp1);
      outf=fopen(nbuf,"w"); if(outf==NULL) outf=stdout;
    }
    if(https) {
      soc=gethttps(p1); goto read;
    }
    soc=net_connect(p1);
    write(soc,tbuf,strlen(tbuf));
      /* header */
    read: if(soc==-1) return 1;
    c=-1;
    while(read(soc,pbuf,1)>0) {
      if(pbuf[0]=='\r') continue;
      fputc(pbuf[0],stderr);
      if((c=='\n') && (pbuf[0]=='\n')) break; else c=pbuf[0];
    }
      /* body */
    charcnt=0;
    while(read(soc,pbuf,1)>0 && charcnt<MAX_WEBGETFLEN) {
      fputc(pbuf[0],outf); charcnt++;
    }
    close(soc);
    if(outf!=stdout) fclose(outf);
    if(https) unlink(tfname);
    return 0;
}


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