url.c

/*****************************************************************************
 *                                  _   _ ____  _     
 *  Project                     ___| | | |  _ \| |    
 *                             / __| | | | |_) | |    
 *                            | (__| |_| |  _ <| |___ 
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) 2000, Daniel Stenberg, <daniel@haxx.se>, et al.
 *
 * In order to be useful for every potential user, curl and libcurl are
 * dual-licensed under the MPL and the MIT/X-derivate licenses.
 *
 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
 * copies of the Software, and permit persons to whom the Software is
 * furnished to do so, under the terms of the MPL or the MIT/X-derivate
 * licenses. You may pick one of these licenses.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 * $Id$
 *****************************************************************************/

/* -- WIN32 approved -- */

#include "setup.h"

#include <stdio.h>
#include <string.h>
#include <stdarg.h>
#include <stdlib.h>
#include <ctype.h>
#include <sys/types.h>
#include <sys/stat.h>

#include <errno.h>

#if defined(WIN32) && !defined(__GNUC__) || defined(__MINGW32__)
#include <winsock.h>
#include <time.h>
#include <io.h>
#else
#ifdef HAVE_SYS_SOCKET_H
#include <sys/socket.h>
#endif
#include <netinet/in.h>
#include <sys/time.h>
#include <sys/resource.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <netdb.h>
#ifdef HAVE_ARPA_INET_H
#include <arpa/inet.h>
#endif
#ifdef HAVE_NET_IF_H
#include <net/if.h>
#endif
#include <sys/ioctl.h>
#include <signal.h>

#ifdef HAVE_SYS_PARAM_H
#include <sys/param.h>
#endif

#ifdef HAVE_SYS_SELECT_H
#include <sys/select.h>
#endif

#ifndef HAVE_SELECT
#error "We can't compile without select() support!"
#endif
#ifndef HAVE_SOCKET
#error "We can't compile without socket() support!"
#endif

#endif

#include "urldata.h"
#include "netrc.h"

#include "formdata.h"
#include "getenv.h"
#include "base64.h"
#include "ssluse.h"
#include "hostip.h"
#include "if2ip.h"
#include "download.h"
#include "sendf.h"
#include "getpass.h"
#include "progress.h"
#include "cookie.h"
#include "strequal.h"
#include "escape.h"

/* And now for the protocols */
#include "ftp.h"
#include "dict.h"
#include "telnet.h"
#include "http.h"
#include "file.h"
#include "ldap.h"

#include <curl/types.h>

#define _MPRINTF_REPLACE /* use our functions only */
#include <curl/mprintf.h>

#ifdef KRB4
#include "security.h"
#endif
/* The last #include file should be: */
#ifdef MALLOCDEBUG
#include "memdebug.h"
#endif

/* -- -- */


CURLcode _urlget(struct UrlData *data);

/* does nothing, returns OK */
CURLcode curl_init(void)
{
  return CURLE_OK;
}

/* does nothing */
void curl_free(void)
{
}

void static urlfree(struct UrlData *data, bool totally)
{
#ifdef USE_SSLEAY
  if (data->ssl.use) {
    if(data->ssl.handle) {
      (void)SSL_shutdown(data->ssl.handle);
      SSL_set_connect_state(data->ssl.handle);

      SSL_free (data->ssl.handle);
      data->ssl.handle = NULL;
    }
    if(data->ssl.ctx) {
      SSL_CTX_free (data->ssl.ctx);
      data->ssl.ctx = NULL;
    }
    data->ssl.use = FALSE; /* get back to ordinary socket usage */
  }
#endif /* USE_SSLEAY */

  /* close possibly still open sockets */
  if(-1 != data->secondarysocket) {
    sclose(data->secondarysocket);
    data->secondarysocket = -1;	
  }
  if(-1 != data->firstsocket) {
    sclose(data->firstsocket);
    data->firstsocket=-1;
  }

  if(data->bits.proxystringalloc) {
    data->bits.proxystringalloc=FALSE;;
    free(data->proxy);
    data->proxy=NULL;

    /* Since we allocated the string the previous round, it means that we
       "discovered" the proxy in the environment variables and thus we must
       switch off that knowledge again... */
    data->bits.httpproxy=FALSE;
  }
  
  if(data->bits.rangestringalloc) {
    free(data->range);
    data->range=NULL;
    data->bits.rangestringalloc=0; /* free now */
  }

  if(data->ptr_proxyuserpwd) {
    free(data->ptr_proxyuserpwd);
    data->ptr_proxyuserpwd=NULL;
  }
  if(data->ptr_uagent) {
    free(data->ptr_uagent);
    data->ptr_uagent=NULL;
  }
  if(data->ptr_userpwd) {
    free(data->ptr_userpwd);
    data->ptr_userpwd=NULL;
  }
  if(data->ptr_rangeline) {
    free(data->ptr_rangeline);
    data->ptr_rangeline=NULL;
  }
  if(data->ptr_ref) {
    free(data->ptr_ref);
    data->ptr_ref=NULL;
  }
  if(data->ptr_cookie) {
    free(data->ptr_cookie);
    data->ptr_cookie=NULL;
  }
  if(data->ptr_host) {
    free(data->ptr_host);
    data->ptr_host=NULL;
  }

  if(totally) {
    /* we let the switch decide whether we're doing a part or total
       cleanup */

    /* check for allocated [URL] memory to free: */
    if(data->freethis)
      free(data->freethis);

    if(data->headerbuff)
      free(data->headerbuff);

    if(data->free_referer)
      free(data->referer);

    if(data->bits.urlstringalloc)
      /* the URL is allocated, free it! */
      free(data->url);

    Curl_cookie_cleanup(data->cookies);

    free(data);

    /* global cleanup */
    curl_free();
  }
}

CURLcode curl_close(CURL *curl)
{
  struct UrlData *data=(struct UrlData *)curl;
  
  void *protocol = data->proto.generic;

  /* total session cleanup (frees 'data' as well!)*/
  urlfree(data, TRUE);

  if(protocol)
    free(protocol);

  return CURLE_OK;
}

static
int my_getpass(void *clientp, char *prompt, char* buffer, int buflen )
{
  char *retbuf;
  retbuf = getpass_r(prompt, buffer, buflen);
  if(NULL == retbuf)
    return 1;
  else
    return 0; /* success */
}


CURLcode curl_open(CURL **curl, char *url)
{
  /* We don't yet support specifying the URL at this point */
  struct UrlData *data;

  /* Very simple start-up: alloc the struct, init it with zeroes and return */
  data = (struct UrlData *)malloc(sizeof(struct UrlData));
  if(data) {
    memset(data, 0, sizeof(struct UrlData));
    data->handle = STRUCT_OPEN;
    data->interf = CURLI_NORMAL; /* normal interface by default */

    /* We do some initial setup here, all those fields that can't be just 0 */

    data-> headerbuff=(char*)malloc(HEADERSIZE);
    if(!data->headerbuff) {
      free(data); /* free the memory again */
      return CURLE_OUT_OF_MEMORY;
    }

    data-> headersize=HEADERSIZE;

    data->out = stdout; /* default output to stdout */
    data->in  = stdin;  /* default input from stdin */
    data->err  = stderr;  /* default stderr to stderr */

    data->firstsocket = -1; /* no file descriptor */
    data->secondarysocket = -1; /* no file descriptor */

    /* use fwrite as default function to store output */
    data->fwrite = (size_t (*)(char *, size_t, size_t, FILE *))fwrite;

    /* use fread as default function to read input */
    data->fread = (size_t (*)(char *, size_t, size_t, FILE *))fread;

    /* set the default passwd function */
    data->fpasswd = my_getpass;

    data->infilesize = -1; /* we don't know any size */

    data->current_speed = -1; /* init to negative == impossible */

    *curl = data;
    return CURLE_OK;
  }

  /* this is a very serious error */
  return CURLE_OUT_OF_MEMORY;
}

CURLcode curl_setopt(CURL *curl, CURLoption option, ...)
{
  struct UrlData *data = curl;
  va_list param;
  char *cookiefile;

  va_start(param, option);

  switch(option) {
  case CURLOPT_VERBOSE:
    data->bits.verbose = va_arg(param, long)?TRUE:FALSE;
    break;
  case CURLOPT_HEADER:
    data->bits.http_include_header = va_arg(param, long)?TRUE:FALSE;
    break;
  case CURLOPT_NOPROGRESS:
    data->bits.hide_progress = va_arg(param, long)?TRUE:FALSE;
    if(data->bits.hide_progress)
      data->progress.flags |= PGRS_HIDE;
    break;
  case CURLOPT_NOBODY:
    data->bits.no_body = va_arg(param, long)?TRUE:FALSE;
    break;
  case CURLOPT_FAILONERROR:
    data->bits.http_fail_on_error = va_arg(param, long)?TRUE:FALSE;
    break;
  case CURLOPT_UPLOAD:
    data->bits.upload = va_arg(param, long)?TRUE:FALSE;
    break;
  case CURLOPT_POST:
    data->bits.http_post = va_arg(param, long)?TRUE:FALSE;
    break;
  case CURLOPT_FILETIME:
    data->bits.get_filetime = va_arg(param, long)?TRUE:FALSE;
    break;
  case CURLOPT_FTPLISTONLY:
    data->bits.ftp_list_only = va_arg(param, long)?TRUE:FALSE;
    break;
  case CURLOPT_FTPAPPEND:
    data->bits.ftp_append = va_arg(param, long)?TRUE:FALSE;
    break;
  case CURLOPT_NETRC:
    data->bits.use_netrc = va_arg(param, long)?TRUE:FALSE;
    break;
  case CURLOPT_FOLLOWLOCATION:
    data->bits.http_follow_location = va_arg(param, long)?TRUE:FALSE;
    break;
  case CURLOPT_FTPASCII:
    data->bits.ftp_ascii = va_arg(param, long)?TRUE:FALSE;
    break;
  case CURLOPT_PUT:
    data->bits.http_put = va_arg(param, long)?TRUE:FALSE;
    break;
  case CURLOPT_MUTE:
    data->bits.mute = va_arg(param, long)?TRUE:FALSE;
    break;

  case CURLOPT_TIMECONDITION:
    data->timecondition = va_arg(param, long);
    break;

  case CURLOPT_TIMEVALUE:
    data->timevalue = va_arg(param, long);
    break;

  case CURLOPT_SSLVERSION:
    data->ssl.version = va_arg(param, long);
    break;

  case CURLOPT_COOKIEFILE:
    cookiefile = (char *)va_arg(param, void *);
    if(cookiefile) {
      data->cookies = Curl_cookie_init(cookiefile);
    }
    break;
  case CURLOPT_WRITEHEADER:
    data->writeheader = (FILE *)va_arg(param, FILE *);
    break;
  case CURLOPT_COOKIE:
    data->cookie = va_arg(param, char *);
    break;
  case CURLOPT_ERRORBUFFER:
    data->errorbuffer = va_arg(param, char *);
    break;
  case CURLOPT_FILE:
    data->out = va_arg(param, FILE *);
    break;
  case CURLOPT_FTPPORT:
    data->ftpport = va_arg(param, char *);
    data->bits.ftp_use_port = data->ftpport?1:0;
    break;
  case CURLOPT_HTTPHEADER:
    data->headers = va_arg(param, struct curl_slist *);
    break;
  case CURLOPT_CUSTOMREQUEST:
    data->customrequest = va_arg(param, char *);
    break;
  case CURLOPT_HTTPPOST:
    data->httppost = va_arg(param, struct HttpPost *);
    data->bits.http_formpost = data->httppost?1:0;
    break;
  case CURLOPT_INFILE:
    data->in = va_arg(param, FILE *);
    break;
  case CURLOPT_INFILESIZE:
    data->infilesize = va_arg(param, long);
    break;
  case CURLOPT_LOW_SPEED_LIMIT:
    data->low_speed_limit=va_arg(param, long);
    break;
  case CURLOPT_LOW_SPEED_TIME:
    data->low_speed_time=va_arg(param, long);
    break;
  case CURLOPT_URL:
    data->url = va_arg(param, char *);
    break;
  case CURLOPT_PORT:
    data->port = va_arg(param, long);
    break;
  case CURLOPT_POSTFIELDS:
    data->postfields = va_arg(param, char *);
    break;
  case CURLOPT_POSTFIELDSIZE:
    data->postfieldsize = va_arg(param, long);
    break;
  case CURLOPT_REFERER:
    data->referer = va_arg(param, char *);
    data->bits.http_set_referer = (data->referer && *data->referer)?1:0;
    break;
  case CURLOPT_AUTOREFERER:
    data->bits.http_auto_referer = va_arg(param, long)?1:0;
    break;
  case CURLOPT_PROXY:
    data->proxy = va_arg(param, char *);
    data->bits.httpproxy = data->proxy?1:0;
    break;
  case CURLOPT_HTTPPROXYTUNNEL:
    data->bits.tunnel_thru_httpproxy = va_arg(param, long)?TRUE:FALSE;
    break;
  case CURLOPT_PROXYPORT:
    data->proxyport = va_arg(param, long);
    break;
  case CURLOPT_TIMEOUT:
    data->timeout = va_arg(param, long);
    break;
  case CURLOPT_MAXREDIRS:
    data->maxredirs = va_arg(param, long);
    break;
  case CURLOPT_USERAGENT:
    data->useragent = va_arg(param, char *);
    break;
  case CURLOPT_USERPWD:
    data->userpwd = va_arg(param, char *);
    data->bits.user_passwd = data->userpwd?1:0;
    break;
  case CURLOPT_POSTQUOTE:
    data->postquote = va_arg(param, struct curl_slist *);
    break;
  case CURLOPT_PROGRESSFUNCTION:
    data->fprogress = va_arg(param, curl_progress_callback);
    data->progress.callback = TRUE; /* no longer internal */
    break;
  case CURLOPT_PROGRESSDATA:
    data->progress_client = va_arg(param, void *);
    break;
  case CURLOPT_PASSWDFUNCTION:
    data->fpasswd = va_arg(param, curl_passwd_callback);
    break;
  case CURLOPT_PASSWDDATA:
    data->passwd_client = va_arg(param, void *);
    break;
  case CURLOPT_PROXYUSERPWD:
    data->proxyuserpwd = va_arg(param, char *);
    data->bits.proxy_user_passwd = data->proxyuserpwd?1:0;
    break;
  case CURLOPT_RANGE:
    data->range = va_arg(param, char *);
    data->bits.set_range = data->range?1:0;
    break;
  case CURLOPT_RESUME_FROM:
    data->resume_from = va_arg(param, long);
    break;
  case CURLOPT_STDERR:
    data->err = va_arg(param, FILE *);
    break;
  case CURLOPT_WRITEFUNCTION:
    data->fwrite = va_arg(param, curl_write_callback);
    break;
  case CURLOPT_READFUNCTION:
    data->fread = va_arg(param, curl_read_callback);
    break;
  case CURLOPT_SSLCERT:
    data->cert = va_arg(param, char *);
    break;
  case CURLOPT_SSLCERTPASSWD:
    data->cert_passwd = va_arg(param, char *);
    break;
  case CURLOPT_CRLF:
    data->crlf = va_arg(param, long);
    break;
  case CURLOPT_QUOTE:
    data->quote = va_arg(param, struct curl_slist *);
    break;
  case CURLOPT_INTERFACE:
    data->device = va_arg(param, char *);
    break;
  case CURLOPT_KRB4LEVEL:
    data->krb4_level = va_arg(param, char *);
    data->bits.krb4=data->krb4_level?TRUE:FALSE;
    break;
  case CURLOPT_SSL_VERIFYPEER:
    data->ssl.verifypeer = va_arg(param, long);
    break;
  case CURLOPT_CAINFO:
    data->ssl.CAfile = va_arg(param, char *);
    data->ssl.CApath = NULL; /*This does not work on windows.*/
    break;
  default:
    /* unknown tag and its companion, just ignore: */
    return CURLE_READ_ERROR; /* correct this */
  }
  return CURLE_OK;
}

#ifndef WIN32
#ifndef RETSIGTYPE
#define RETSIGTYPE void
#endif
static
RETSIGTYPE alarmfunc(int signal)
{
  /* this is for "-ansi -Wall -pedantic" to stop complaining!   (rabe) */
  (void)signal;
  return;
}
#endif

CURLcode curl_write(CURLconnect *c_conn, char *buf, size_t amount,
                   size_t *n)
{
  struct connectdata *conn = (struct connectdata *)c_conn;
  struct UrlData *data;
  size_t bytes_written;

  if(!n || !conn || (conn->handle != STRUCT_CONNECT))
    return CURLE_FAILED_INIT;
  data = conn->data;

#ifdef USE_SSLEAY
  if (data->ssl.use) {
    bytes_written = SSL_write(data->ssl.handle, buf, amount);
  }
  else {
#endif
#ifdef KRB4
    if(conn->sec_complete)
      bytes_written = sec_write(conn, conn->writesockfd, buf, amount);
    else
#endif
      bytes_written = swrite(conn->writesockfd, buf, amount);
#ifdef USE_SSLEAY
  }
#endif /* USE_SSLEAY */

  *n = bytes_written;
  return CURLE_OK;
}

CURLcode curl_read(CURLconnect *c_conn, char *buf, size_t buffersize,
                   size_t *n)
{
  struct connectdata *conn = (struct connectdata *)c_conn;
  struct UrlData *data;
  size_t nread;

  if(!n || !conn || (conn->handle != STRUCT_CONNECT))
    return CURLE_FAILED_INIT;
  data = conn->data;

#ifdef USE_SSLEAY
  if (data->ssl.use) {
    nread = SSL_read (data->ssl.handle, buf, buffersize);
  }
  else {
#endif
#ifdef KRB4
    if(conn->sec_complete)
      nread = sec_read(conn, conn->sockfd, buf, buffersize);
    else
#endif
      nread = sread (conn->sockfd, buf, buffersize);
#ifdef USE_SSLEAY
  }
#endif /* USE_SSLEAY */
  *n = nread;
  return CURLE_OK;
}

CURLcode curl_disconnect(CURLconnect *c_connect)
{
  struct connectdata *conn = c_connect;

  struct UrlData *data = conn->data;

  if(conn->hostent_buf) /* host name info */
    free(conn->hostent_buf);

  if(conn->path) /* the URL path part */
    free(conn->path);

  free(conn); /* free the connection oriented data */

  /* clean up the sockets and SSL stuff from the previous "round" */
  urlfree(data, FALSE);

  return CURLE_OK;
}

static CURLcode _connect(CURL *curl, CURLconnect **in_connect)
{
  char *tmp;
  char *buf;
  CURLcode result;
  char resumerange[40]="";
  struct UrlData *data = curl;
  struct connectdata *conn;
#ifdef HAVE_SIGACTION
  struct sigaction sigact;
#endif
  int urllen;

  if(!data || (data->handle != STRUCT_OPEN))
    return CURLE_BAD_FUNCTION_ARGUMENT; /* TBD: make error codes */

  if(!data->url)
    return CURLE_URL_MALFORMAT;

  conn = (struct connectdata *)malloc(sizeof(struct connectdata));
  if(!conn) {
    *in_connect = NULL; /* clear the pointer */
    return CURLE_OUT_OF_MEMORY;
  }
  *in_connect = conn;

  memset(conn, 0, sizeof(struct connectdata));
  conn->handle = STRUCT_CONNECT;

  conn->data = data; /* remember our daddy */
  conn->state = CONN_INIT;

  conn->upload_bufsize = UPLOAD_BUFSIZE; /* the smallest upload buffer size
                                            we use */

  buf = data->buffer; /* this is our buffer */

#ifdef HAVE_SIGACTION
  sigaction(SIGALRM, NULL, &sigact);
  sigact.sa_handler = alarmfunc;
#ifdef SA_RESTART
  /* HPUX doesn't have SA_RESTART but defaults to that behaviour! */
  sigact.sa_flags &= ~SA_RESTART;
#endif
  sigaction(SIGALRM, &sigact, NULL);
#else
  /* no sigaction(), revert to the much lamer signal() */
#ifdef HAVE_SIGNAL
  signal(SIGALRM, alarmfunc);
#endif

#endif

  /* We need to allocate memory to store the path in. We get the size of the
     full URL to be sure, and we need to make it at least 256 bytes since
     other parts of the code will rely on this fact */
#define LEAST_PATH_ALLOC 256
  urllen=strlen(data->url);
  if(urllen < LEAST_PATH_ALLOC)
    urllen=LEAST_PATH_ALLOC;
  
  conn->path=(char *)malloc(urllen);
  if(NULL == conn->path)
    return CURLE_OUT_OF_MEMORY; /* really bad error */

  /* Parse <url> */
  /* We need to parse the url, even when using the proxy, because
   * we will need the hostname and port in case we are trying
   * to SSL connect through the proxy -- and we don't know if we
   * will need to use SSL until we parse the url ...
   */
  if((2 == sscanf(data->url, "%64[^:]://%[^\n]",
                  conn->proto,
                  conn->path)) && strequal(conn->proto, "file")) {
    /* we deal with file://<host>/<path> differently since it
       supports no hostname other than "localhost" and "127.0.0.1",
       which is unique among the protocols specified in RFC 1738 */
    if (strnequal(conn->path, "localhost/", 10) ||
        strnequal(conn->path, "127.0.0.1/", 10))
      /* ... since coincidentally both host strings are of equal length
         otherwise, <host>/ is quietly ommitted */
      strcpy(conn->path, &conn->path[10]);

    strcpy(conn->proto, "file");
  }
  else {
    /* Set default host and default path */
    strcpy(conn->gname, "curl.haxx.se");
    strcpy(conn->path, "/");

    if (2 > sscanf(data->url,
                   "%64[^\n:]://%256[^\n/]%[^\n]",
                   conn->proto, conn->gname, conn->path)) {
      
      /* badly formatted, let's try the browser-style _without_ 'http://' */
      if((1 > sscanf(data->url, "%256[^\n/]%[^\n]",
                     conn->gname, conn->path)) ) {
        failf(data, "<url> malformed");
        return CURLE_URL_MALFORMAT;
      }
      if(strnequal(conn->gname, "FTP", 3)) {
        strcpy(conn->proto, "ftp");
      }
      else if(strnequal(conn->gname, "GOPHER", 6))
        strcpy(conn->proto, "gopher");
#ifdef USE_SSLEAY
      else if(strnequal(conn->gname, "HTTPS", 5))
        strcpy(conn->proto, "https");
#endif /* USE_SSLEAY */
      else if(strnequal(conn->gname, "TELNET", 6))
        strcpy(conn->proto, "telnet");
      else if (strnequal(conn->gname, "DICT", sizeof("DICT")-1))
        strcpy(conn->proto, "DICT");
      else if (strnequal(conn->gname, "LDAP", sizeof("LDAP")-1))
        strcpy(conn->proto, "LDAP");
      else {
        strcpy(conn->proto, "http");
      }

      conn->protocol |= PROT_MISSING; /* not given in URL */
    }
  }


  if(data->bits.user_passwd && !data->bits.use_netrc) {
    data->user[0] =0;
    data->passwd[0]=0;

    if(*data->userpwd != ':') {
      /* the name is given, get user+password */
      sscanf(data->userpwd, "%127[^:]:%127[^\n]",
             data->user, data->passwd);
      }
    else
      /* no name given, get the password only */
      sscanf(data->userpwd+1, "%127[^\n]", data->passwd);

    /* check for password, if no ask for one */
    if( !data->passwd[0] ) {
      if(!data->fpasswd ||
         data->fpasswd(data->passwd_client,
                       "password:", data->passwd, sizeof(data->passwd)))
        return CURLE_BAD_PASSWORD_ENTERED;
    }
  }

  if(data->bits.proxy_user_passwd) {
    data->proxyuser[0] =0;
    data->proxypasswd[0]=0;

    if(*data->proxyuserpwd != ':') {
      /* the name is given, get user+password */
      sscanf(data->proxyuserpwd, "%127[^:]:%127[^\n]",
             data->proxyuser, data->proxypasswd);
      }
    else
      /* no name given, get the password only */
      sscanf(data->proxyuserpwd+1, "%127[^\n]", data->proxypasswd);

    /* check for password, if no ask for one */
    if( !data->proxypasswd[0] ) {
      if(!data->fpasswd ||
         data->fpasswd( data->passwd_client,
                        "proxy password:",
                        data->proxypasswd,
                        sizeof(data->proxypasswd)))
        return CURLE_BAD_PASSWORD_ENTERED;
    }

  }

  conn->name = conn->gname;
  conn->ppath = conn->path;
  data->hostname = conn->name;


  if(!data->bits.httpproxy) {
    /* If proxy was not specified, we check for default proxy environment
       variables, to enable i.e Lynx compliance:

       http_proxy=http://some.server.dom:port/
       https_proxy=http://some.server.dom:port/
       ftp_proxy=http://some.server.dom:port/
       gopher_proxy=http://some.server.dom:port/
       no_proxy=domain1.dom,host.domain2.dom
                                 (a comma-separated list of hosts which should
                                  not be proxied, or an asterisk to override
                                  all proxy variables)
       all_proxy=http://some.server.dom:port/
                                 (seems to exist for the CERN www lib. Probably
                                  the first to check for.)

       For compatibility, the all-uppercase versions of these variables are
       checked if the lowercase versions don't exist.
       */
    char *no_proxy=NULL;
    char *proxy=NULL;
    char proxy_env[128];

    no_proxy=curl_getenv("no_proxy");
    if(!no_proxy)
      no_proxy=curl_getenv("NO_PROXY");

    if(!no_proxy || !strequal("*", no_proxy)) {
      /* NO_PROXY wasn't specified or it wasn't just an asterisk */
      char *nope;

      nope=no_proxy?strtok(no_proxy, ", "):NULL;
      while(nope) {
        if(strlen(nope) <= strlen(conn->name)) {
          char *checkn=
            conn->name + strlen(conn->name) - strlen(nope);
          if(strnequal(nope, checkn, strlen(nope))) {
            /* no proxy for this host! */
            break;
          }
        }
	nope=strtok(NULL, ", ");
      }
      if(!nope) {
	/* It was not listed as without proxy */
	char *protop = conn->proto;
	char *envp = proxy_env;
	char *prox;

	/* Now, build <protocol>_proxy and check for such a one to use */
	while(*protop)
	  *envp++ = tolower(*protop++);

	/* append _proxy */
	strcpy(envp, "_proxy");

	/* read the protocol proxy: */
	prox=curl_getenv(proxy_env);

	if(!prox) {
          /* There was no lowercase variable, try the uppercase version: */
	  for(envp = proxy_env; *envp; envp++)
	    *envp = toupper(*envp);
	  prox=curl_getenv(proxy_env);
	}

	if(prox && *prox) { /* don't count "" strings */
	  proxy = prox; /* use this */
	}
	else {
	  proxy = curl_getenv("all_proxy"); /* default proxy to use */
	  if(!proxy)
            proxy=curl_getenv("ALL_PROXY");
	}

        if(proxy && *proxy) {
          /* we have a proxy here to set */
          data->proxy = proxy;
          data->bits.proxystringalloc=1; /* this needs to be freed later */
          data->bits.httpproxy=1;
        }
      } /* if (!nope) - it wasn't specified non-proxy */
    } /* NO_PROXY wasn't specified or '*' */
    if(no_proxy)
      free(no_proxy);
  } /* if not using proxy */

  if((conn->protocol&PROT_MISSING) && data->bits.httpproxy ) {
    /* We're guessing prefixes here and since we're told to use a proxy, we
       need to add the protocol prefix to the URL string before we continue!
       */
    char *reurl;

    reurl = aprintf("%s://%s", conn->proto, data->url);

    if(!reurl)
      return CURLE_OUT_OF_MEMORY;

    data->url = reurl;
    if(data->freethis)
      free(data->freethis);
    data->freethis = reurl;

    conn->protocol &= ~PROT_MISSING; /* switch that one off again */
  }

  /* RESUME on a HTTP page is a tricky business. First, let's just check that
     'range' isn't used, then set the range parameter and leave the resume as
     it is to inform about this situation for later use. We will then
     "attempt" to resume, and if we're talking to a HTTP/1.1 (or later)
     server, we will get the document resumed. If we talk to a HTTP/1.0
     server, we just fail since we can't rewind the file writing from within
     this function. */
  if(data->resume_from) {
    if(!data->bits.set_range) {
      /* if it already was in use, we just skip this */
      snprintf(resumerange, sizeof(resumerange), "%d-", data->resume_from);
      data->range=strdup(resumerange); /* tell ourselves to fetch this range */
      data->bits.rangestringalloc = TRUE; /* mark as allocated */
      data->bits.set_range = 1; /* switch on range usage */
    }
  }


  if(data->timeout) {
    /* We set the timeout on the connection/resolving phase first, separately
       from the download/upload part to allow a maximum time on everything */
    myalarm(data->timeout); /* this sends a signal when the timeout fires
			       off, and that will abort system calls */
  }

  /*
   * Hmm, if we are using a proxy, then we can skip the GOPHER and the
   * FTP steps, although we cannot skip the HTTPS step (since the proxy
   * works differently, depending on whether its SSL or not).
   */

  if (strequal(conn->proto, "HTTP")) {
    if(!data->port)
      data->port = PORT_HTTP;
    data->remote_port = PORT_HTTP;
    conn->protocol |= PROT_HTTP;
    conn->curl_do = Curl_http;
    conn->curl_done = Curl_http_done;
    conn->curl_close = Curl_http_close;
  }
  else if (strequal(conn->proto, "HTTPS")) {
#ifdef USE_SSLEAY
    if(!data->port)
      data->port = PORT_HTTPS;
    data->remote_port = PORT_HTTPS;
    conn->protocol |= PROT_HTTP;
    conn->protocol |= PROT_HTTPS;

    conn->curl_do = Curl_http;
    conn->curl_done = Curl_http_done;
    conn->curl_connect = Curl_http_connect;
    conn->curl_close = Curl_http_close;

#else /* USE_SSLEAY */
    failf(data, "libcurl was built with SSL disabled, https: not supported!");
    return CURLE_UNSUPPORTED_PROTOCOL;
#endif /* !USE_SSLEAY */
  }
  else if (strequal(conn->proto, "GOPHER")) {
    if(!data->port)
      data->port = PORT_GOPHER;
    data->remote_port = PORT_GOPHER;
    /* Skip /<item-type>/ in path if present */
    if (isdigit((int)conn->path[1])) {
      conn->ppath = strchr(&conn->path[1], '/');
      if (conn->ppath == NULL)
	conn->ppath = conn->path;
      }
    conn->protocol |= PROT_GOPHER;
    conn->curl_do = Curl_http;
    conn->curl_done = Curl_http_done;
    conn->curl_close = Curl_http_close;
  }
  else if(strequal(conn->proto, "FTP")) {
    char *type;
    if(!data->port)
      data->port = PORT_FTP;
    data->remote_port = PORT_FTP;
    conn->protocol |= PROT_FTP;

    if(data->bits.httpproxy &&
       !data->bits.tunnel_thru_httpproxy) {
      /* Unless we have asked to tunnel ftp operations through the proxy, we
         switch and use HTTP operations only */
      conn->curl_do = Curl_http;
      conn->curl_done = Curl_http_done;
      conn->curl_close = Curl_http_close;
    }
    else {