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 "base64.h"
#include "ssluse.h"
#include "hostip.h"
#include "if2ip.h"
#include "transfer.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 */

    data->httpreq = HTTPREQ_GET; /* Default HTTP request */

    *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;
    if(data->bits.upload)
      /* If this is HTTP, PUT is what's needed to "upload" */
      data->httpreq = HTTPREQ_PUT;
    break;
  case CURLOPT_POST:
    data->bits.http_post = va_arg(param, long)?TRUE:FALSE;
    if(data->bits.http_post)
      data->httpreq = HTTPREQ_POST;
    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;
    if(data->bits.http_put)
      data->httpreq = HTTPREQ_PUT;
    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 *);
    if(data->customrequest)
      data->httpreq = HTTPREQ_CUSTOM;
    break;
  case CURLOPT_HTTPPOST:
    data->httppost = va_arg(param, struct HttpPost *);
    data->bits.http_formpost = data->httppost?1:0;
    if(data->bits.http_formpost)
      data->httpreq = HTTPREQ_POST_FORM;
    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;
}

#if !defined(WIN32)||defined(__CYGWIN32__)
#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_disconnect(CURLconnect *c_connect)
{
  struct connectdata *conn = c_connect;

  struct UrlData *data = conn->data;

#ifdef ENABLE_IPV6
  if(conn->res) /* host name info */
    freeaddrinfo(conn->res);
#else
  if(conn->hostent_buf) /* host name info */
    free(conn->hostent_buf);
#endif

  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;
  char endbracket;
#ifdef HAVE_SIGACTION
  struct sigaction sigact;
#endif
  int urllen;
#ifdef ENABLE_IPV6
  struct addrinfo *ai;
#endif

  /*************************************************************
   * Check input data
   *************************************************************/

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

  if(!data->url)
    return CURLE_URL_MALFORMAT;

  /*************************************************************
   * Allocate and initiate a connection struct
   *************************************************************/
  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 */

  /*************************************************************
   * Set signal handler
   *************************************************************/
#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 the 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 URL protocols specified in RFC 1738
     */

    if (strnequal(conn->path, "localhost/", 10) ||
        strnequal(conn->path, "127.0.0.1/", 10))
      /* If there's another host name than the one we support, <host>/ is
       * quietly ommitted */
      strcpy(conn->path, &conn->path[10]);

    strcpy(conn->proto, "file"); /* store protocol string lowercase */
  }
  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)) {
      
      /*
       * The URL was badly formatted, let's try the browser-style _without_
       * protocol specified like 'http://'.
       */
      if((1 > sscanf(data->url, "%256[^\n/]%[^\n]",
                     conn->gname, conn->path)) ) {
        /*
         * We couldn't even get this format.
         */
        failf(data, "<url> malformed");
        return CURLE_URL_MALFORMAT;
      }

      /*
       * Since there was no protocol part specified, we guess what protocol it
       * is based on the first letters of the server name.
       */

      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 */
    }
  }

  /*************************************************************
   * Take care of user and password authentication stuff
   *************************************************************/

  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;
    }
  }

  /*************************************************************
   * Take care of proxy authentication stuff
   *************************************************************/
  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;
    }

  }

  /*************************************************************
   * Set a few convenience pointers 
   *************************************************************/
  conn->name = conn->gname;
  conn->ppath = conn->path;
  data->hostname = conn->name;


  /*************************************************************
   * Detect what (if any) proxy to use
   *************************************************************/
  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 */

  /*************************************************************
   * No protocol but proxy usage needs attention
   *************************************************************/
  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 */
    }
  }

  /*************************************************************
   * Set timeout if that is being used
   *************************************************************/
  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 */
  }

  /*************************************************************
   * Setup internals depending on protocol
   *************************************************************/

  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;