/*
** Copyright (c) 2006 D. Richard Hipp
**
** This program is free software; you can redistribute it and/or
** modify it under the terms of the Simplified BSD License (also
** known as the "2-Clause License" or "FreeBSD License".)
**
** 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.
**
** Author contact information:
**   drh@hwaci.com
**   http://www.hwaci.com/drh/
**
*******************************************************************************
**
** This file began as a set of C functions and procedures used intepret
** CGI environment variables for Fossil web pages that were invoked by
** CGI.  That's where the file name comes from.  But over the years it
** has grown to incorporate lots of related functionality, including:
**
**   *  Interpreting CGI environment variables when Fossil is run as
**      CGI (the original purpose).
**
**   *  Interpreting HTTP requests received directly or via an SSH tunnel.
**
**   *  Interpreting SCGI requests
**
**   *  Generating appropriate replies to CGI, SCGI, and HTTP requests.
**
**   *  Listening for incoming HTTP requests and dispatching them.
**      (Used by "fossil ui" and "fossil server", for example).
**
** So, even though the name of this file implies that it only deals with
** CGI, in fact, the code in this file is used to interpret webpage requests
** received by a variety of means, and to generate well-formatted replies
** to those requests.
**
** The code in this file abstracts the web-request so that downstream
** modules that generate the body of the reply (based on the requested page)
** do not need to know if the request is coming from CGI, direct HTTP, 
** SCGI, or some other means.
**
** This module gathers information about web page request into a key/value
** store.  Keys and values come from:
**
**    *  Query parameters
**    *  POST parameter
**    *  Cookies
**    *  Environment variables
**
** The parameters are accessed using cgi_parameter() and similar functions
** or their convenience macros P() and similar.
**
** Environment variable parameters are set as if the request were coming
** in over CGI even if the request arrived via SCGI or direct HTTP.  Thus
** the downstream modules that are trying to interpret the request do not
** need to know the request protocol - they can just request the values
** of environment variables and everything will always work.
**
** This file contains routines used by Fossil when it is acting as a
** CGI client.  For the code used by Fossil when it is acting as a
** CGI server (for the /ext webpage) see the "extcgi.c" source file.
*/
#include "config.h"
#ifdef _WIN32
# if !defined(_WIN32_WINNT)
#  define _WIN32_WINNT 0x0501
# endif
# include <winsock2.h>
# include <ws2tcpip.h>
#else
# include <sys/socket.h>
# include <netinet/in.h>
# include <arpa/inet.h>
# include <sys/times.h>
# include <sys/time.h>
# include <sys/wait.h>
# include <sys/select.h>
#endif
#ifdef __EMX__
  typedef int socklen_t;
#endif
#include <time.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <assert.h>
#include "cgi.h"
#include "cygsup.h"

#if INTERFACE
/*
** Shortcuts for cgi_parameter.  P("x") returns the value of query parameter
** or cookie "x", or NULL if there is no such parameter or cookie.  PD("x","y")
** does the same except "y" is returned in place of NULL if there is not match.
*/
#define P(x)        cgi_parameter((x),0)
#define PD(x,y)     cgi_parameter((x),(y))
#define PT(x)       cgi_parameter_trimmed((x),0)
#define PDT(x,y)    cgi_parameter_trimmed((x),(y))
#define PB(x)       cgi_parameter_boolean(x)
#define PCK(x)      cgi_parameter_checked(x,1)
#define PIF(x,y)    cgi_parameter_checked(x,y)

/*
** Shortcut for the cgi_printf() routine.  Instead of using the
**
**    @ ...
**
** notation provided by the translate.c utility, you can also
** optionally use:
**
**    CX(...)
*/
#define CX cgi_printf

/*
** Destinations for output text.
*/
#define CGI_HEADER   0
#define CGI_BODY     1

/*
** Flags for SSH HTTP clients
*/
#define CGI_SSH_CLIENT           0x0001     /* Client is SSH */
#define CGI_SSH_COMPAT           0x0002     /* Compat for old SSH transport */
#define CGI_SSH_FOSSIL           0x0004     /* Use new Fossil SSH transport */

#endif /* INTERFACE */

/*
** The reply content is generated in two pieces: the header and the body.
** These pieces are generated separately because they are not necessarily
** produced in order.  Parts of the header might be built after all or
** part of the body.  The header and body are accumulated in separate
** Blob structures then output sequentially once everything has been
** built.
**
** Do not confuse the content header with the HTTP header. The content header
** is generated by downstream code.  The HTTP header is generated by the
** cgi_reply() routine below.
**
** The content header and contenty body are *approximately* the <head>
** element and the <body> elements for HTML replies.  However this is only
** approximate. The content header also includes parts of <body> that
** show the banner and menu bar at the top of each page.  Also note that
** not all replies are HTML, but there can still be separate header and
** body sections of the content.
**
** The cgi_destination() interface switches between the buffers.
*/
static Blob cgiContent[2] = { BLOB_INITIALIZER, BLOB_INITIALIZER };
static Blob *pContent = &cgiContent[0];

/*
** Set the destination buffer into which to accumulate CGI content.
*/
void cgi_destination(int dest){
  switch( dest ){
    case CGI_HEADER: {
      pContent = &cgiContent[0];
      break;
    }
    case CGI_BODY: {
      pContent = &cgiContent[1];
      break;
    }
    default: {
      cgi_panic("bad destination");
    }
  }
}

/*
** Check to see if the content header or body contains the zNeedle string.
** Return true if it does and false if it does not.
*/
int cgi_header_contains(const char *zNeedle){
  return strstr(blob_str(&cgiContent[0]), zNeedle)!=0;
}
int cgi_body_contains(const char *zNeedle){
  return strstr(blob_str(&cgiContent[1]), zNeedle)!=0;
}

/*
** Append new reply content to what already exists.
*/
void cgi_append_content(const char *zData, int nAmt){
  blob_append(pContent, zData, nAmt);
}

/*
** Reset both reply content buffers to be empty.
*/
void cgi_reset_content(void){
  blob_reset(&cgiContent[0]);
  blob_reset(&cgiContent[1]);
}

/*
** Return a pointer to Blob that is currently accumulating reply content.
*/
Blob *cgi_output_blob(void){
  return pContent;
}

/*
** Return the content header as a text string
*/
const char *cgi_header(void){
  return blob_str(&cgiContent[0]);
}

/*
** Combine the header and body content all into the header buffer.
** In other words, append the body content to the end of the header
** content.
*/
static void cgi_combine_header_and_body(void){
  int size = blob_size(&cgiContent[1]);
  if( size>0 ){
    blob_append(&cgiContent[0], blob_buffer(&cgiContent[1]), size);
    blob_reset(&cgiContent[1]);
  }
}

/*
** Return a pointer to the combined header+body content.
*/
char *cgi_extract_content(void){
  cgi_combine_header_and_body();
  return blob_buffer(&cgiContent[0]);
}

/*
** Additional information used to form the HTTP reply
*/
static const char *zContentType = "text/html";   /* Content type of the reply */
static const char *zReplyStatus = "OK";          /* Reply status description */
static int iReplyStatus = 200;               /* Reply status code */
static Blob extraHeader = BLOB_INITIALIZER;  /* Extra header text */
static int rangeStart = 0;                   /* Start of Range: */
static int rangeEnd = 0;                     /* End of Range: plus 1 */

/*
** Set the reply content type.
**
** The reply content type defaults to "text/html".  It only needs to be
** changed (by calling this routine) in the exceptional case where some
** other content type is being returned.
*/
void cgi_set_content_type(const char *zType){
  zContentType = fossil_strdup(zType);
}

/*
** Erase any existing reply content.  Replace is with a pNewContent.
**
** This routine erases pNewContent.  In other words, it move pNewContent
** into the content buffer.
*/
void cgi_set_content(Blob *pNewContent){
  cgi_reset_content();
  cgi_destination(CGI_HEADER);
  cgiContent[0] = *pNewContent;
  blob_zero(pNewContent);
}

/*
** Set the reply status code
*/
void cgi_set_status(int iStat, const char *zStat){
  zReplyStatus = fossil_strdup(zStat);
  iReplyStatus = iStat;
}

/*
** Append text to the content header buffer.
*/
void cgi_append_header(const char *zLine){
  blob_append(&extraHeader, zLine, -1);
}
void cgi_printf_header(const char *zLine, ...){
  va_list ap;
  va_start(ap, zLine);
  blob_vappendf(&extraHeader, zLine, ap);
  va_end(ap);
}

/*
** Set a cookie by queuing up the appropriate HTTP header output. If
** !g.isHTTP, this is a no-op.
**
** Zero lifetime implies a session cookie. A negative one expires
** the cookie immediately.
*/
void cgi_set_cookie(
  const char *zName,    /* Name of the cookie */
  const char *zValue,   /* Value of the cookie.  Automatically escaped */
  const char *zPath,    /* Path cookie applies to.  NULL means "/" */
  int lifetime          /* Expiration of the cookie in seconds from now */
){
  char const *zSecure = "";
  if(!g.isHTTP) return /* e.g. JSON CLI mode, where g.zTop is not set */;
  else if( zPath==0 ){
    zPath = g.zTop;
    if( zPath[0]==0 ) zPath = "/";
  }
  if( g.zBaseURL!=0 && strncmp(g.zBaseURL, "https:", 6)==0 ){
    zSecure = " secure;";
  }
  if( lifetime!=0 ){
    blob_appendf(&extraHeader,
       "Set-Cookie: %s=%t; Path=%s; max-age=%d; HttpOnly; "
       "%s Version=1\r\n",
       zName, lifetime>0 ? zValue : "null", zPath, lifetime, zSecure);
  }else{
    blob_appendf(&extraHeader,
       "Set-Cookie: %s=%t; Path=%s; HttpOnly; "
       "%s Version=1\r\n",
       zName, zValue, zPath, zSecure);
  }
}


/*
** Return true if the response should be sent with Content-Encoding: gzip.
*/
static int is_gzippable(void){
  if( g.fNoHttpCompress ) return 0;
  if( strstr(PD("HTTP_ACCEPT_ENCODING", ""), "gzip")==0 ) return 0;
  return strncmp(zContentType, "text/", 5)==0
    || sqlite3_strglob("application/*xml", zContentType)==0
    || sqlite3_strglob("application/*javascript", zContentType)==0;
}


/*
** The following routines read or write content from/to the wire for
** an HTTP request.  Depending on settings the content might be coming
** from or going to a socket, or a file, or it might come from or go
** to an SSL decoder/encoder.
*/
/*
** Works like fgets():
**
** Read a single line of input into s[].  Ensure that s[] is zero-terminated.
** The s[] buffer is size bytes and so at most size-1 bytes will be read.
**
** Return a pointer to s[] on success, or NULL at end-of-input.
*/
static char *cgi_fgets(char *s, int size){
  if( !g.httpUseSSL ){
    return fgets(s, size, g.httpIn);
  }
#ifdef FOSSIL_ENABLE_SSL
  return ssl_gets(g.httpSSLConn, s, size);
#else
  fossil_fatal("SSL not available");
#endif
}

/* Works like fread():
**
** Read as many as bytes of content as we can, up to a maximum of nmemb
** bytes.  Return the number of bytes read.  Return 0 if there is no
** further input or if an I/O error occurs.
*/
size_t cgi_fread(void *ptr, size_t nmemb){
  if( !g.httpUseSSL ){
    return fread(ptr, 1, nmemb, g.httpIn);
  }
#ifdef FOSSIL_ENABLE_SSL
  return ssl_read_server(g.httpSSLConn, ptr, nmemb, 1);
#else
  fossil_fatal("SSL not available");
#endif
}

/* Works like feof():
**
** Return true if end-of-input has been reached.
*/
int cgi_feof(void){
  if( !g.httpUseSSL ){
    return feof(g.httpIn);
  }
#ifdef FOSSIL_ENABLE_SSL
  return ssl_eof(g.httpSSLConn);
#else
  return 1;
#endif
}

/* Works like fwrite():
**
** Try to output nmemb bytes of content.  Return the number of
** bytes actually written.
*/
static size_t cgi_fwrite(void *ptr, size_t nmemb){
  if( !g.httpUseSSL ){
    return fwrite(ptr, 1, nmemb, g.httpOut);
  }
#ifdef FOSSIL_ENABLE_SSL
  return ssl_write_server(g.httpSSLConn, ptr, nmemb);
#else
  fossil_fatal("SSL not available");
#endif
}

/* Works like fflush():
**
** Make sure I/O has completed.
*/
static void cgi_fflush(void){
  if( !g.httpUseSSL ){
    fflush(g.httpOut);
  }
}


/*
** Generate the reply to a web request.  The output might be an
** full HTTP response, or a CGI response, depending on how things have
** be set up.
**
** The reply consists of a response header (an HTTP or CGI response header)
** followed by the concatenation of the content header and content body.
*/
void cgi_reply(void){
  Blob hdr = BLOB_INITIALIZER;
  int total_size;
  if( iReplyStatus<=0 ){
    iReplyStatus = 200;
    zReplyStatus = "OK";
  }

  if( g.fullHttpReply ){
    if( rangeEnd>0
     && iReplyStatus==200 
     && fossil_strcmp(P("REQUEST_METHOD"),"GET")==0
    ){
      iReplyStatus = 206;
      zReplyStatus = "Partial Content";
    }
    blob_appendf(&hdr, "HTTP/1.0 %d %s\r\n", iReplyStatus, zReplyStatus);
    blob_appendf(&hdr, "Date: %s\r\n", cgi_rfc822_datestamp(time(0)));
    blob_appendf(&hdr, "Connection: close\r\n");
    blob_appendf(&hdr, "X-UA-Compatible: IE=edge\r\n");
  }else{
    assert( rangeEnd==0 );
    blob_appendf(&hdr, "Status: %d %s\r\n", iReplyStatus, zReplyStatus);
  }
  if( etag_tag()[0]!=0 ){
    blob_appendf(&hdr, "ETag: %s\r\n", etag_tag());
    blob_appendf(&hdr, "Cache-Control: max-age=%d\r\n", etag_maxage());
    if( etag_mtime()>0 ){
      blob_appendf(&hdr, "Last-Modified: %s\r\n",
              cgi_rfc822_datestamp(etag_mtime()));
    }
  }else if( g.isConst ){
    /* isConst means that the reply is guaranteed to be invariant, even
    ** after configuration changes and/or Fossil binary recompiles. */
    blob_appendf(&hdr, "Cache-Control: max-age=315360000, immutable\r\n");
  }else{
    blob_appendf(&hdr, "Cache-control: no-cache\r\n");
  }

  if( blob_size(&extraHeader)>0 ){
    blob_appendf(&hdr, "%s", blob_buffer(&extraHeader));
  }

  /* Add headers to turn on useful security options in browsers. */
  blob_appendf(&hdr, "X-Frame-Options: SAMEORIGIN\r\n");
  /* This stops fossil pages appearing in frames or iframes, preventing
  ** click-jacking attacks on supporting browsers.
  **
  ** Other good headers would be
  **   Strict-Transport-Security: max-age=62208000
  ** if we're using https. However, this would break sites which serve different
  ** content on http and https protocols. Also,
  **   X-Content-Security-Policy: allow 'self'
  ** would help mitigate some XSS and data injection attacks, but will break
  ** deliberate inclusion of external resources, such as JavaScript syntax
  ** highlighter scripts.
  **
  ** These headers are probably best added by the web server hosting fossil as
  ** a CGI script.
  */

  /* Content intended for logged in users should only be cached in
  ** the browser, not some shared location.
  */
  if( iReplyStatus!=304 ) {
    blob_appendf(&hdr, "Content-Type: %s; charset=utf-8\r\n", zContentType);
    if( fossil_strcmp(zContentType,"application/x-fossil")==0 ){
      cgi_combine_header_and_body();
      blob_compress(&cgiContent[0], &cgiContent[0]);
    }

    if( is_gzippable() && iReplyStatus!=206 ){
      int i;
      gzip_begin(0);
      for( i=0; i<2; i++ ){
        int size = blob_size(&cgiContent[i]);
        if( size>0 ) gzip_step(blob_buffer(&cgiContent[i]), size);
        blob_reset(&cgiContent[i]);
      }
      gzip_finish(&cgiContent[0]);
      blob_appendf(&hdr, "Content-Encoding: gzip\r\n");
      blob_appendf(&hdr, "Vary: Accept-Encoding\r\n");
    }
    total_size = blob_size(&cgiContent[0]) + blob_size(&cgiContent[1]);
    if( iReplyStatus==206 ){
      blob_appendf(&hdr, "Content-Range: bytes %d-%d/%d\r\n",
              rangeStart, rangeEnd-1, total_size);
      total_size = rangeEnd - rangeStart; 
    }
    blob_appendf(&hdr, "Content-Length: %d\r\n", total_size);
  }else{
    total_size = 0;
  }
  blob_appendf(&hdr, "\r\n");
  cgi_fwrite(blob_buffer(&hdr), blob_size(&hdr));
  blob_reset(&hdr);
  if( total_size>0
   && iReplyStatus!=304
   && fossil_strcmp(P("REQUEST_METHOD"),"HEAD")!=0
  ){
    int i, size;
    for(i=0; i<2; i++){
      size = blob_size(&cgiContent[i]);
      if( size<=rangeStart ){
        rangeStart -= size;
      }else{
        int n = size - rangeStart;
        if( n>total_size ){
          n = total_size;
        }
        cgi_fwrite(blob_buffer(&cgiContent[i])+rangeStart, n);
        rangeStart = 0;
        total_size -= n;
      }
    }
  }
  cgi_fflush();
  CGIDEBUG(("-------- END cgi ---------\n"));

  /* After the webpage has been sent, do any useful background
  ** processing.
  */
  g.cgiOutput = 2;
  if( g.db!=0 && iReplyStatus==200 ){
    backoffice_check_if_needed();
  }
}

/*
** Generate an HTTP or CGI redirect response that causes a redirect
** to the URL given in the argument.
**
** The URL must be relative to the base of the fossil server.
*/
NORETURN void cgi_redirect_with_status(
  const char *zURL,
  int iStat,
  const char *zStat
){
  char *zLocation;
  CGIDEBUG(("redirect to %s\n", zURL));
  if( strncmp(zURL,"http:",5)==0 || strncmp(zURL,"https:",6)==0 ){
    zLocation = mprintf("Location: %s\r\n", zURL);
  }else if( *zURL=='/' ){
    int n1 = (int)strlen(g.zBaseURL);
    int n2 = (int)strlen(g.zTop);
    if( g.zBaseURL[n1-1]=='/' ) zURL++;
    zLocation = mprintf("Location: %.*s%s\r\n", n1-n2, g.zBaseURL, zURL);
  }else{
    zLocation = mprintf("Location: %s/%s\r\n", g.zBaseURL, zURL);
  }
  cgi_append_header(zLocation);
  cgi_reset_content();
  cgi_printf("<html>\n<p>Redirect to %h</p>\n</html>\n", zLocation);
  cgi_set_status(iStat, zStat);
  free(zLocation);
  cgi_reply();
  fossil_exit(0);
}
NORETURN void cgi_redirect(const char *zURL){
  cgi_redirect_with_status(zURL, 302, "Moved Temporarily");
}
NORETURN void cgi_redirect_with_method(const char *zURL){
  cgi_redirect_with_status(zURL, 307, "Temporary Redirect");
}
NORETURN void cgi_redirectf(const char *zFormat, ...){
  va_list ap;
  va_start(ap, zFormat);
  cgi_redirect(vmprintf(zFormat, ap));
  va_end(ap);
}

/*
** Add a "Content-disposition: attachment; filename=%s" header to the reply.
*/
void cgi_content_disposition_filename(const char *zFilename){
  char *z;
  int i, n;

           /*  0123456789 123456789 123456789 123456789 123456*/
  z = mprintf("Content-Disposition: attachment; filename=\"%s\";\r\n",
                    file_tail(zFilename));
  n = (int)strlen(z);
  for(i=43; i<n-4; i++){
    char c = z[i];
    if( fossil_isalnum(c) ) continue;
    if( c=='.' || c=='-' || c=='/' ) continue;
    z[i] = '_';
  }
  cgi_append_header(z);
  fossil_free(z);
}

/*
** Return the URL for the caller.  This is obtained from either the
** "referer" CGI parameter, if it exists, or the HTTP_REFERER HTTP parameter.
** If neither exist, return zDefault.
*/
const char *cgi_referer(const char *zDefault){
  const char *zRef = P("referer");
  if( zRef==0 ){
    zRef = P("HTTP_REFERER");
    if( zRef==0 ) zRef = zDefault;
  }
  return zRef;
}

/*
** Return true if the current request appears to be safe from a
** Cross-Site Request Forgery (CSRF) attack.  Conditions that must
** be met:
**
**    *   The HTTP_REFERER must have the same origin
**    *   The REQUEST_METHOD must be POST - or requirePost==0
*/
int cgi_csrf_safe(int requirePost){
  const char *zRef = P("HTTP_REFERER");
  int nBase;
  if( zRef==0 ) return 0;
  if( requirePost ){
    const char *zMethod = P("REQUEST_METHOD");
    if( zMethod==0 ) return 0;
    if( strcmp(zMethod,"POST")!=0 ) return 0;
  }
  nBase = (int)strlen(g.zBaseURL);
  if( strncmp(g.zBaseURL,zRef,nBase)!=0 ) return 0;
  if( zRef[nBase]!=0 && zRef[nBase]!='/' ) return 0;
  return 1;
}

/*
** Information about all query parameters, post parameter, cookies and
** CGI environment variables are stored in a hash table as follows:
*/
static int nAllocQP = 0; /* Space allocated for aParamQP[] */
static int nUsedQP = 0;  /* Space actually used in aParamQP[] */
static int sortQP = 0;   /* True if aParamQP[] needs sorting */
static int seqQP = 0;    /* Sequence numbers */
static struct QParam {   /* One entry for each query parameter or cookie */
  const char *zName;        /* Parameter or cookie name */
  const char *zValue;       /* Value of the query parameter or cookie */
  int seq;                  /* Order of insertion */
  char isQP;                /* True for query parameters */
  char cTag;                /* Tag on query parameters */
} *aParamQP;             /* An array of all parameters and cookies */

/*
** Add another query parameter or cookie to the parameter set.
** zName is the name of the query parameter or cookie and zValue
** is its fully decoded value.
**
** zName and zValue are not copied and must not change or be
** deallocated after this routine returns.
*/
void cgi_set_parameter_nocopy(const char *zName, const char *zValue, int isQP){
  if( nAllocQP<=nUsedQP ){
    nAllocQP = nAllocQP*2 + 10;
    if( nAllocQP>1000 ){
      /* Prevent a DOS service attack against the framework */
      fossil_fatal("Too many query parameters");
    }
    aParamQP = fossil_realloc( aParamQP, nAllocQP*sizeof(aParamQP[0]) );
  }
  aParamQP[nUsedQP].zName = zName;
  aParamQP[nUsedQP].zValue = zValue;
  if( g.fHttpTrace ){
    fprintf(stderr, "# cgi: %s = [%s]\n", zName, zValue);
  }
  aParamQP[nUsedQP].seq = seqQP++;
  aParamQP[nUsedQP].isQP = isQP;
  aParamQP[nUsedQP].cTag = 0;
  nUsedQP++;
  sortQP = 1;
}

/*
** Add another query parameter or cookie to the parameter set.
** zName is the name of the query parameter or cookie and zValue
** is its fully decoded value.  zName will be modified to be an
** all lowercase string.
**
** zName and zValue are not copied and must not change or be
** deallocated after this routine returns.  This routine changes
** all ASCII alphabetic characters in zName to lower case.  The
** caller must not change them back.
*/
void cgi_set_parameter_nocopy_tolower(
  char *zName,
  const char *zValue,
  int isQP
){
  int i;
  for(i=0; zName[i]; i++){ zName[i] = fossil_tolower(zName[i]); }
  cgi_set_parameter_nocopy(zName, zValue, isQP);
}

/*
** Add another query parameter or cookie to the parameter set.
** zName is the name of the query parameter or cookie and zValue
** is its fully decoded value.
**
** Copies are made of both the zName and zValue parameters.
*/
void cgi_set_parameter(const char *zName, const char *zValue){
  cgi_set_parameter_nocopy(fossil_strdup(zName),fossil_strdup(zValue), 0);
}
void cgi_set_query_parameter(const char *zName, const char *zValue){
  cgi_set_parameter_nocopy(fossil_strdup(zName),fossil_strdup(zValue), 1);
}

/*
** Replace a parameter with a new value.
*/
void cgi_replace_parameter(const char *zName, const char *zValue){
  int i;
  for(i=0; i<nUsedQP; i++){
    if( fossil_strcmp(aParamQP[i].zName,zName)==0 ){
      aParamQP[i].zValue = zValue;
      return;
    }
  }
  cgi_set_parameter_nocopy(zName, zValue, 0);
}
void cgi_replace_query_parameter(const char *zName, const char *zValue){
  int i;
  for(i=0; i<nUsedQP; i++){
    if( fossil_strcmp(aParamQP[i].zName,zName)==0 ){
      aParamQP[i].zValue = zValue;
      assert( aParamQP[i].isQP );
      return;
    }
  }
  cgi_set_parameter_nocopy(zName, zValue, 1);
}
void cgi_replace_query_parameter_tolower(char *zName, const char *zValue){
  int i;
  for(i=0; zName[i]; i++){ zName[i] = fossil_tolower(zName[i]); }
  cgi_replace_query_parameter(zName, zValue);
}

/*
** Delete a parameter.
*/
void cgi_delete_parameter(const char *zName){
  int i;
  for(i=0; i<nUsedQP; i++){
    if( fossil_strcmp(aParamQP[i].zName,zName)==0 ){
      --nUsedQP;
      if( i<nUsedQP ){
        memmove(aParamQP+i, aParamQP+i+1, sizeof(*aParamQP)*(nUsedQP-i));
      }
      return;
    }
  }
}
void cgi_delete_query_parameter(const char *zName){
  int i;
  for(i=0; i<nUsedQP; i++){
    if( fossil_strcmp(aParamQP[i].zName,zName)==0 ){
      assert( aParamQP[i].isQP );
      --nUsedQP;
      if( i<nUsedQP ){
        memmove(aParamQP+i, aParamQP+i+1, sizeof(*aParamQP)*(nUsedQP-i));
      }
      return;
    }
  }
}

/*
** Add an environment varaible value to the parameter set.  The zName
** portion is fixed but a copy is be made of zValue.
*/
void cgi_setenv(const char *zName, const char *zValue){
  cgi_set_parameter_nocopy(zName, fossil_strdup(zValue), 0);
}

/*
** Add a list of query parameters or cookies to the parameter set.
**
** Each parameter is of the form NAME=VALUE.  Both the NAME and the
** VALUE may be url-encoded ("+" for space, "%HH" for other special
** characters).  But this routine assumes that NAME contains no
** special character and therefore does not decode it.
**
** If NAME begins with another other than a lower-case letter then
** the entire NAME=VALUE term is ignored.  Hence:
**
**      *  cookies and query parameters that have uppercase names
**         are ignored.
**
**      *  it is impossible for a cookie or query parameter to
**         override the value of an environment variable since
**         environment variables always have uppercase names.
**
** 2018-03-29:  Also ignore the entry if NAME that contains any characters
** other than [a-zA-Z0-9_].  There are no known exploits involving unusual
** names that contain characters outside that set, but it never hurts to
** be extra cautious when sanitizing inputs.
**
** Parameters are separated by the "terminator" character.  Whitespace
** before the NAME is ignored.
**
** The input string "z" is modified but no copies is made.  "z"
** should not be deallocated or changed again after this routine
** returns or it will corrupt the parameter table.
*/
static void add_param_list(char *z, int terminator){
  int isQP = terminator=='&';
  while( *z ){
    char *zName;
    char *zValue;
    while( fossil_isspace(*z) ){ z++; }
    zName = z;
    while( *z && *z!='=' && *z!=terminator ){ z++; }
    if( *z=='=' ){
      *z = 0;
      z++;
      zValue = z;
      while( *z && *z!=terminator ){ z++; }
      if( *z ){
        *z = 0;
        z++;
      }
      dehttpize(zValue);
    }else{
      if( *z ){ *z++ = 0; }
      zValue = "";
    }
    if( zName[0] && fossil_no_strange_characters(zName+1) ){
      if( fossil_islower(zName[0]) ){
        cgi_set_parameter_nocopy(zName, zValue, isQP);
      }else if( fossil_isupper(zName[0]) ){
        cgi_set_parameter_nocopy_tolower(zName, zValue, isQP);
      }
    }
#ifdef FOSSIL_ENABLE_JSON
    json_setenv( zName, cson_value_new_string(zValue,strlen(zValue)) );
#endif /* FOSSIL_ENABLE_JSON */
  }
}

/*
** *pz is a string that consists of multiple lines of text.  This
** routine finds the end of the current line of text and converts
** the "\n" or "\r\n" that ends that line into a "\000".  It then
** advances *pz to the beginning of the next line and returns the
** previous value of *pz (which is the start of the current line.)
*/
static char *get_line_from_string(char **pz, int *pLen){
  char *z = *pz;
  int i;
  if( z[0]==0 ) return 0;
  for(i=0; z[i]; i++){
    if( z[i]=='\n' ){
      if( i>0 && z[i-1]=='\r' ){
        z[i-1] = 0;
      }else{
        z[i] = 0;
      }
      i++;
      break;
    }
  }
  *pz = &z[i];
  *pLen -= i;
  return z;
}

/*
** The input *pz points to content that is terminated by a "\r\n"
** followed by the boundary marker zBoundary.  An extra "--" may or
** may not be appended to the boundary marker.  There are *pLen characters
** in *pz.
**
** This routine adds a "\000" to the end of the content (overwriting
** the "\r\n") and returns a pointer to the content.  The *pz input
** is adjusted to point to the first line following the boundary.
** The length of the content is stored in *pnContent.
*/
static char *get_bounded_content(
  char **pz,         /* Content taken from here */
  int *pLen,         /* Number of bytes of data in (*pz)[] */
  char *zBoundary,    /* Boundary text marking the end of content */
  int *pnContent     /* Write the size of the content here */
){
  char *z = *pz;
  int len = *pLen;
  int i;
  int nBoundary = strlen(zBoundary);
  *pnContent = len;
  for(i=0; i<len; i++){
    if( z[i]=='\n' && strncmp(zBoundary, &z[i+1], nBoundary)==0 ){
      if( i>0 && z[i-1]=='\r' ) i--;
      z[i] = 0;
      *pnContent = i;
      i += nBoundary;
      break;
    }
  }
  *pz = &z[i];
  get_line_from_string(pz, pLen);
  return z;
}

/*
** Tokenize a line of text into as many as nArg tokens.  Make
** azArg[] point to the start of each token.
**
** Tokens consist of space or semi-colon delimited words or
** strings inside double-quotes.  Example:
**
**    content-disposition: form-data; name="fn"; filename="index.html"
**
** The line above is tokenized as follows:
**
**    azArg[0] = "content-disposition:"
**    azArg[1] = "form-data"
**    azArg[2] = "name="
**    azArg[3] = "fn"
**    azArg[4] = "filename="
**    azArg[5] = "index.html"
**    azArg[6] = 0;
**
** '\000' characters are inserted in z[] at the end of each token.
** This routine returns the total number of tokens on the line, 6
** in the example above.
*/
static int tokenize_line(char *z, int mxArg, char **azArg){
  int i = 0;
  while( *z ){
    while( fossil_isspace(*z) || *z==';' ){ z++; }
    if( *z=='"' && z[1] ){
      *z = 0;
      z++;
      if( i<mxArg-1 ){ azArg[i++] = z; }
      while( *z && *z!='"' ){ z++; }
      if( *z==0 ) break;
      *z = 0;
      z++;
    }else{
      if( i<mxArg-1 ){ azArg[i++] = z; }
      while( *z && !fossil_isspace(*z) && *z!=';' && *z!='"' ){ z++; }
      if( *z && *z!='"' ){
        *z = 0;
        z++;
      }
    }
  }
  azArg[i] = 0;
  return i;
}

/*
** Scan the multipart-form content and make appropriate entries
** into the parameter table.
**
** The content string "z" is modified by this routine but it is
** not copied.  The calling function must not deallocate or modify
** "z" after this routine finishes or it could corrupt the parameter
** table.
*/
static void process_multipart_form_data(char *z, int len){
  char *zLine;
  int nArg, i;
  char *zBoundary;
  char *zValue;
  char *zName = 0;
  int showBytes = 0;
  char *azArg[50];

  zBoundary = get_line_from_string(&z, &len);
  if( zBoundary==0 ) return;
  while( (zLine = get_line_from_string(&z, &len))!=0 ){
    if( zLine[0]==0 ){
      int nContent = 0;
      zValue = get_bounded_content(&z, &len, zBoundary, &nContent);
      if( zName && zValue ){
        if( fossil_islower(zName[0]) ){
          cgi_set_parameter_nocopy(zName, zValue, 1);
          if( showBytes ){
            cgi_set_parameter_nocopy(mprintf("%s:bytes", zName),
                 mprintf("%d",nContent), 1);
          }
        }else if( fossil_isupper(zName[0]) ){
          cgi_set_parameter_nocopy_tolower(zName, zValue, 1);
          if( showBytes ){
            cgi_set_parameter_nocopy_tolower(mprintf("%s:bytes", zName),
                 mprintf("%d",nContent), 1);
          }
        }
      }
      zName = 0;
      showBytes = 0;
    }else{
      nArg = tokenize_line(zLine, count(azArg), azArg);
      for(i=0; i<nArg; i++){
        int c = fossil_tolower(azArg[i][0]);
        int n = strlen(azArg[i]);
        if( c=='c' && sqlite3_strnicmp(azArg[i],"content-disposition:",n)==0 ){
          i++;
        }else if( c=='n' && sqlite3_strnicmp(azArg[i],"name=",n)==0 ){
          zName = azArg[++i];
        }else if( c=='f' && sqlite3_strnicmp(azArg[i],"filename=",n)==0 ){
          char *z = azArg[++i];
          if( zName && z ){
            if( fossil_islower(zName[0]) ){
              cgi_set_parameter_nocopy(mprintf("%s:filename",zName), z, 1);
            }else if( fossil_isupper(zName[0]) ){
              cgi_set_parameter_nocopy_tolower(mprintf("%s:filename",zName),
                                               z, 1);
            }
          }
          showBytes = 1;
        }else if( c=='c' && sqlite3_strnicmp(azArg[i],"content-type:",n)==0 ){
          char *z = azArg[++i];
          if( zName && z ){
            if( fossil_islower(zName[0]) ){
              cgi_set_parameter_nocopy(mprintf("%s:mimetype",zName), z, 1);
            }else if( fossil_isupper(zName[0]) ){
              cgi_set_parameter_nocopy_tolower(mprintf("%s:mimetype",zName),
                                               z, 1);
            }
          }
        }
      }
    }
  }
}


#ifdef FOSSIL_ENABLE_JSON
/*
** Reads a JSON object from the given blob, which is assumed to have
** been populated by the caller from stdin, the SSL API, or a file, as
** appropriate for the particular use case. On success g.json.post is
** updated to hold the content. On error a FSL_JSON_E_INVALID_REQUEST
** response is output and fossil_exit() is called (in HTTP mode exit
** code 0 is used).
*/
void cgi_parse_POST_JSON( Blob * pIn ){
  cson_value * jv = NULL;
  cson_parse_info pinfo = cson_parse_info_empty;
  assert(g.json.gc.a && "json_bootstrap_early() was not called!");
  jv = cson_parse_Blob(pIn, &pinfo);
  if( jv==NULL ){
    goto invalidRequest;
  }else{
    json_gc_add( "POST.JSON", jv );
    g.json.post.v = jv;
    g.json.post.o = cson_value_get_object( jv );
    if( !g.json.post.o ){ /* we don't support non-Object (Array) requests */
      goto invalidRequest;
    }
  }
  return;
  invalidRequest:
  cgi_set_content_type(json_guess_content_type());
  if(0 != pinfo.errorCode){ /* fancy error message */
      char * msg = mprintf("JSON parse error at line %u, column %u, "
                           "byte offset %u: %s",
                           pinfo.line, pinfo.col, pinfo.length,
                           cson_rc_string(pinfo.errorCode));
      json_err( FSL_JSON_E_INVALID_REQUEST, msg, 1 );
      fossil_free(msg);
  }else if(jv && !g.json.post.o){
      json_err( FSL_JSON_E_INVALID_REQUEST,
                "Request envelope must be a JSON Object (not array).", 1 );
  }else{ /* generic error message */
      json_err( FSL_JSON_E_INVALID_REQUEST, NULL, 1 );
  }
  fossil_exit( g.isHTTP ? 0 : 1);
}
#endif /* FOSSIL_ENABLE_JSON */

/*
** Log HTTP traffic to a file.  Begin the log on first use.  Close the log
** when the argument is NULL.
*/
void cgi_trace(const char *z){
  static FILE *pLog = 0;
  if( g.fHttpTrace==0 ) return;
  if( z==0 ){
    if( pLog ) fclose(pLog);
    pLog = 0;
    return;
  }
  if( pLog==0 ){
    char zFile[50];
#if defined(_WIN32)
    unsigned r;
    sqlite3_randomness(sizeof(r), &r);
    sqlite3_snprintf(sizeof(zFile), zFile, "httplog-%08x.txt", r);
#else
    sqlite3_snprintf(sizeof(zFile), zFile, "httplog-%05d.txt", getpid());
#endif
    pLog = fossil_fopen(zFile, "wb");
    if( pLog ){
      fprintf(stderr, "# open log on %s\n", zFile);
    }else{
      fprintf(stderr, "# failed to open %s\n", zFile);
      return;
    }
  }
  fputs(z, pLog);
}

/* Forward declaration */
static NORETURN void malformed_request(const char *zMsg);

/*
** Checks the QUERY_STRING environment variable, sets it up
** via add_param_list() and, if found, applies its "skin"
** setting. Returns 0 if no QUERY_STRING is set, 1 if it is,
** and 2 if it sets the skin (in which case the cookie may
** still need flushing by the page, via cookie_render()).
*/
int cgi_setup_query_string(void){
  int rc = 0;
  char * z = (char*)P("QUERY_STRING");
  if( z ){
    ++rc;
    z = fossil_strdup(z);
    add_param_list(z, '&');
    z = (char*)P("skin");
    if(z){
      char *zErr = skin_use_alternative(z, 2);
      ++rc;
      if(!zErr && !P("once")){
        cookie_write_parameter("skin","skin",z);
      }
      fossil_free(zErr);
    }
  }
  return rc;
}

/*
** Initialize the query parameter database.  Information is pulled from
** the QUERY_STRING environment variable (if it exists), from standard
** input if there is POST data, and from HTTP_COOKIE.
**
** REQUEST_URI, PATH_INFO, and SCRIPT_NAME are related as follows:
**
**      REQUEST_URI == SCRIPT_NAME + PATH_INFO
**
** Or if QUERY_STRING is not empty:
**
**      REQUEST_URI == SCRIPT_NAME + PATH_INFO + '?' + QUERY_STRING
**
** Where "+" means concatenate.  Fossil requires SCRIPT_NAME.  If
** REQUEST_URI is provided but PATH_INFO is not, then PATH_INFO is
** computed from REQUEST_URI and SCRIPT_NAME.  If PATH_INFO is provided
** but REQUEST_URI is not, then compute REQUEST_URI from PATH_INFO and
** SCRIPT_NAME.  If neither REQUEST_URI nor PATH_INFO are provided, then
** assume that PATH_INFO is an empty string and set REQUEST_URI equal
** to PATH_INFO.
**
** Sometimes PATH_INFO is missing and SCRIPT_NAME is not a prefix of
** REQUEST_URI.  (See https://fossil-scm.org/forum/forumpost/049e8650ed)
** In that case, truncate SCRIPT_NAME so that it is a proper prefix
** of REQUEST_URI.
**
** SCGI typically omits PATH_INFO.  CGI sometimes omits REQUEST_URI and
** PATH_INFO when it is empty.
**
** CGI Parameter quick reference:
**
**                                   REQUEST_URI
**                           _____________|________________
**                          /                              \
**    https://fossil-scm.org/forum/info/12736b30c072551a?t=c
**    \___/   \____________/\____/\____________________/ \_/
**      |           |          |             |            |
**      |       HTTP_HOST      |        PATH_INFO     QUERY_STRING
**      |                      |
**    REQUEST_SCHEMA         SCRIPT_NAME
**               
*/
void cgi_init(void){
  char *z;
  const char *zType;
  char *zSemi;
  int len;
  const char *zRequestUri = cgi_parameter("REQUEST_URI",0);
  const char *zScriptName = cgi_parameter("SCRIPT_NAME",0);
  const char *zPathInfo = cgi_parameter("PATH_INFO",0);
#ifdef _WIN32
  const char *zServerSoftware = cgi_parameter("SERVER_SOFTWARE",0);
#endif

#ifdef FOSSIL_ENABLE_JSON
  const int noJson = P("no_json")!=0;
#endif
  g.isHTTP = 1;
  cgi_destination(CGI_BODY);

  /* We must have SCRIPT_NAME. If the web server did not supply it, try
  ** to compute it from REQUEST_URI and PATH_INFO. */
  if( zScriptName==0 ){
    if( zRequestUri==0 || zPathInfo==0 ){
      malformed_request("missing SCRIPT_NAME");  /* Does not return */
    }
    z = strstr(zRequestUri,zPathInfo);
    if( z==0 ){
      malformed_request("PATH_INFO not found in REQUEST_URI");
    }
    zScriptName = fossil_strndup(zRequestUri,(int)(z-zRequestUri));
    cgi_set_parameter("SCRIPT_NAME", zScriptName);
  }

#ifdef _WIN32
  /* The Microsoft IIS web server does not define REQUEST_URI, instead it uses
  ** PATH_INFO for virtually the same purpose.  Define REQUEST_URI the same as
  ** PATH_INFO and redefine PATH_INFO with SCRIPT_NAME removed from the 
  ** beginning. */
  if( zServerSoftware && strstr(zServerSoftware, "Microsoft-IIS") ){
    int i, j;
    cgi_set_parameter("REQUEST_URI", zPathInfo);
    for(i=0; zPathInfo[i]==zScriptName[i] && zPathInfo[i]; i++){}
    for(j=i; zPathInfo[j] && zPathInfo[j]!='?'; j++){}
    zPathInfo = fossil_strndup(zPathInfo+i, j-i);
    cgi_replace_parameter("PATH_INFO", zPathInfo);
  }
#endif
  if( zRequestUri==0 ){
    const char *z = zPathInfo;
    const char *zQS = cgi_parameter("QUERY_STRING",0);
    if( zPathInfo==0 ){
      malformed_request("missing PATH_INFO and/or REQUEST_URI");
    }
    if( z[0]=='/' ) z++;
    if( zQS && zQS[0] ){
      zRequestUri = mprintf("%s/%s?%s", zScriptName, z, zQS);
    }else{
      zRequestUri = mprintf("%s/%s", zScriptName, z);
    }
    cgi_set_parameter("REQUEST_URI", zRequestUri);
  }
  if( zPathInfo==0 ){
    int i, j;
    for(i=0; zRequestUri[i]==zScriptName[i] && zRequestUri[i]; i++){}
    for(j=i; zRequestUri[j] && zRequestUri[j]!='?'; j++){}
    zPathInfo = fossil_strndup(zRequestUri+i, j-i);
    cgi_set_parameter_nocopy("PATH_INFO", zPathInfo, 0);
    if( j>i && zScriptName[i]!=0 ){
      /* If SCRIPT_NAME is not a prefix of REQUEST_URI, truncate it so
      ** that it is.  See https://fossil-scm.org/forum/forumpost/049e8650ed
      */
      char *zNew = fossil_strndup(zScriptName, i);
      cgi_replace_parameter("SCRIPT_NAME", zNew);
    }
  }
#ifdef FOSSIL_ENABLE_JSON
  if(noJson==0 && json_request_is_json_api(zPathInfo)){
    /* We need to change some following behaviour depending on whether
    ** we are operating in JSON mode or not. We cannot, however, be
    ** certain whether we should/need to be in JSON mode until the
    ** PATH_INFO is set up.
    */
    g.json.isJsonMode = 1;
    json_bootstrap_early();
  }else{
    assert(!g.json.isJsonMode &&
           "Internal misconfiguration of g.json.isJsonMode");
  }
#endif
  z = (char*)P("HTTP_COOKIE");
  if( z ){
    z = fossil_strdup(z);
    add_param_list(z, ';');
    z = (char*)cookie_value("skin",0);
    if(z){
      skin_use_alternative(z, 2);
    }
  }

  cgi_setup_query_string();

  z = (char*)P("REMOTE_ADDR");
  if( z ){
    g.zIpAddr = fossil_strdup(z);
  }

  len = atoi(PD("CONTENT_LENGTH", "0"));
  zType = P("CONTENT_TYPE");
  zSemi = zType ? strchr(zType, ';') : 0;
  if( zSemi ){
    g.zContentType = fossil_strndup(zType, (int)(zSemi-zType));
    zType = g.zContentType;
  }else{
    g.zContentType = zType;
  }
  blob_zero(&g.cgiIn);
  if( len>0 && zType ){
    if( blob_read_from_cgi(&g.cgiIn, len)<len ){
      char *zMsg = mprintf("CGI content-length mismatch:  Wanted %d bytes"
                           " but got only %d\n", len, blob_size(&g.cgiIn));
      malformed_request(zMsg);
    }
    if( fossil_strcmp(zType, "application/x-fossil")==0 ){
      blob_uncompress(&g.cgiIn, &g.cgiIn);
    }
#ifdef FOSSIL_ENABLE_JSON
    if( noJson==0 && g.json.isJsonMode!=0
        && json_can_consume_content_type(zType)!=0 ){
      cgi_parse_POST_JSON(&g.cgiIn);
      cgi_set_content_type(json_guess_content_type());
    }
#endif /* FOSSIL_ENABLE_JSON */
  }
}

/*
** Decode POST parameter information in the cgiIn content, if any.
*/
void cgi_decode_post_parameters(void){
  int len = blob_size(&g.cgiIn);
  if( len==0 ) return;
  if( fossil_strcmp(g.zContentType,"application/x-www-form-urlencoded")==0
   || strncmp(g.zContentType,"multipart/form-data",19)==0
  ){
    char *z = blob_str(&g.cgiIn);
    cgi_trace(z);
    if( g.zContentType[0]=='a' ){
      add_param_list(z, '&');
    }else{
      process_multipart_form_data(z, len);
    }
    blob_init(&g.cgiIn, 0, 0);
  }
}

/*
** This is the comparison function used to sort the aParamQP[] array of
** query parameters and cookies.
*/
static int qparam_compare(const void *a, const void *b){
  struct QParam *pA = (struct QParam*)a;
  struct QParam *pB = (struct QParam*)b;
  int c;
  c = fossil_strcmp(pA->zName, pB->zName);
  if( c==0 ){
    c = pA->seq - pB->seq;
  }
  return c;
}

/*
** Return the value of a query parameter or cookie whose name is zName.
** If there is no query parameter or cookie named zName and the first
** character of zName is uppercase, then check to see if there is an
** environment variable by that name and return it if there is.  As
** a last resort when nothing else matches, return zDefault.
*/
const char *cgi_parameter(const char *zName, const char *zDefault){
  int lo, hi, mid, c;

  /* The sortQP flag is set whenever a new query parameter is inserted.
  ** It indicates that we need to resort the query parameters.
  */
  if( sortQP ){
    int i, j;
    qsort(aParamQP, nUsedQP, sizeof(aParamQP[0]), qparam_compare);
    sortQP = 0;
    /* After sorting, remove duplicate parameters.  The secondary sort
    ** key is aParamQP[].seq and we keep the first entry.  That means
    ** with duplicate calls to cgi_set_parameter() the second and
    ** subsequent calls are effectively no-ops. */
    for(i=j=1; i<nUsedQP; i++){
      if( fossil_strcmp(aParamQP[i].zName,aParamQP[i-1].zName)==0 ){
        continue;
      }
      if( j<i ){
        memcpy(&aParamQP[j], &aParamQP[i], sizeof(aParamQP[j]));
      }
      j++;
    }
    nUsedQP = j;
  }

  /* Invoking with a NULL zName is just a way to cause the parameters
  ** to be sorted.  So go ahead and bail out in that case */
  if( zName==0 || zName[0]==0 ) return 0;

  /* Do a binary search for a matching query parameter */
  lo = 0;
  hi = nUsedQP-1;
  while( lo<=hi ){
    mid = (lo+hi)/2;
    c = fossil_strcmp(aParamQP[mid].zName, zName);
    if( c==0 ){
      CGIDEBUG(("mem-match [%s] = [%s]\n", zName, aParamQP[mid].zValue));
      return aParamQP[mid].zValue;
    }else if( c>0 ){
      hi = mid-1;
    }else{
      lo = mid+1;
    }
  }

  /* If no match is found and the name begins with an upper-case
  ** letter, then check to see if there is an environment variable
  ** with the given name.
  */
  if( fossil_isupper(zName[0]) ){
    const char *zValue = fossil_getenv(zName);
    if( zValue ){
      cgi_set_parameter_nocopy(zName, zValue, 0);
      CGIDEBUG(("env-match [%s] = [%s]\n", zName, zValue));
      return zValue;
    }
  }
  CGIDEBUG(("no-match [%s]\n", zName));
  return zDefault;
}

/*
** Return the value of the first defined query parameter or cookie whose
** name appears in the list of arguments.  Or if no parameter is found,
** return NULL.
*/
const char *cgi_coalesce(const char *zName, ...){
  va_list ap;
  const char *z;
  const char *zX;
  if( zName==0 ) return 0;
  z = cgi_parameter(zName, 0);
  va_start(ap, zName);
  while( z==0 && (zX = va_arg(ap,const char*))!=0 ){
    z = cgi_parameter(zX, 0);
  }
  va_end(ap);
  return z;
}

/*
** Return the value of a CGI parameter with leading and trailing
** spaces removed and with internal \r\n changed to just \n
*/
char *cgi_parameter_trimmed(const char *zName, const char *zDefault){
  const char *zIn;
  char *zOut, c;
  int i, j;
  zIn = cgi_parameter(zName, 0);
  if( zIn==0 ) zIn = zDefault;
  if( zIn==0 ) return 0;
  while( fossil_isspace(zIn[0]) ) zIn++;
  zOut = fossil_strdup(zIn);
  for(i=j=0; (c = zOut[i])!=0; i++){
    if( c=='\r' && zOut[i+1]=='\n' ) continue;
    zOut[j++] = c;
  }
  zOut[j] = 0;
  while( j>0 && fossil_isspace(zOut[j-1]) ) zOut[--j] = 0;
  return zOut;
}

/*
** Return true if the CGI parameter zName exists and is not equal to 0,
** or "no" or "off".
*/
int cgi_parameter_boolean(const char *zName){
  const char *zIn = cgi_parameter(zName, 0);
  if( zIn==0 ) return 0;
  return zIn[0]==0 || is_truth(zIn);
}

/*
** Return either an empty string "" or the string "checked" depending
** on whether or not parameter zName has value iValue.  If parameter
** zName does not exist, that is assumed to be the same as value 0.
**
** This routine implements the PCK(x) and PIF(x,y) macros.  The PIF(x,y)
** macro generateds " checked" if the value of parameter x equals integer y.
** PCK(x) is the same as PIF(x,1).  These macros are used to generate
** the "checked" attribute on checkbox and radio controls of forms.
*/
const char *cgi_parameter_checked(const char *zName, int iValue){
  const char *zIn = cgi_parameter(zName,0);
  int x;
  if( zIn==0 ){
    x = 0;
  }else if( !fossil_isdigit(zIn[0]) ){
    x = is_truth(zIn);
  }else{
    x = atoi(zIn);
  }
  return x==iValue ? "checked" : "";
}

/*
** Return the name of the i-th CGI parameter.  Return NULL if there
** are fewer than i registered CGI parameters.
*/
const char *cgi_parameter_name(int i){
  if( i>=0 && i<nUsedQP ){
    return aParamQP[i].zName;
  }else{
    return 0;
  }
}

/*
** Print CGI debugging messages.
*/
void cgi_debug(const char *zFormat, ...){
  va_list ap;
  if( g.fDebug ){
    va_start(ap, zFormat);
    vfprintf(g.fDebug, zFormat, ap);
    va_end(ap);
    fflush(g.fDebug);
  }
}

/*
** Return true if any of the query parameters in the argument
** list are defined.
*/
int cgi_any(const char *z, ...){
  va_list ap;
  char *z2;
  if( cgi_parameter(z,0)!=0 ) return 1;
  va_start(ap, z);
  while( (z2 = va_arg(ap, char*))!=0 ){
    if( cgi_parameter(z2,0)!=0 ) return 1;
  }
  va_end(ap);
  return 0;
}

/*
** Return true if all of the query parameters in the argument list
** are defined.
*/
int cgi_all(const char *z, ...){
  va_list ap;
  char *z2;
  if( cgi_parameter(z,0)==0 ) return 0;
  va_start(ap, z);
  while( (z2 = va_arg(ap, char*))==0 ){
    if( cgi_parameter(z2,0)==0 ) return 0;
  }
  va_end(ap);
  return 1;
}

/*
** Load all relevant environment variables into the parameter buffer.
** Invoke this routine prior to calling cgi_print_all() in order to see
** the full CGI environment.  This routine intended for debugging purposes
** only.
*/
void cgi_load_environment(void){
  /* The following is a list of environment variables that Fossil considers
  ** to be "relevant". */
  static const char *const azCgiVars[] = {
    "COMSPEC", "DOCUMENT_ROOT", "GATEWAY_INTERFACE", "SCGI",
    "HTTP_ACCEPT", "HTTP_ACCEPT_CHARSET", "HTTP_ACCEPT_ENCODING",
    "HTTP_ACCEPT_LANGUAGE", "HTTP_AUTHENICATION",
    "HTTP_CONNECTION", "HTTP_HOST",
    "HTTP_IF_NONE_MATCH", "HTTP_IF_MODIFIED_SINCE",
    "HTTP_USER_AGENT", "HTTP_REFERER", "PATH_INFO", "PATH_TRANSLATED",
    "QUERY_STRING", "REMOTE_ADDR", "REMOTE_PORT",
    "REMOTE_USER", "REQUEST_METHOD", "REQUEST_SCHEME",
    "REQUEST_URI", "SCRIPT_FILENAME", "SCRIPT_NAME", "SERVER_NAME",
    "SERVER_PROTOCOL", "HOME", "FOSSIL_HOME", "USERNAME", "USER",
    "FOSSIL_USER", "SQLITE_TMPDIR", "TMPDIR",
    "TEMP", "TMP", "FOSSIL_VFS",
    "FOSSIL_FORCE_TICKET_MODERATION", "FOSSIL_FORCE_WIKI_MODERATION",
    "FOSSIL_TCL_PATH", "TH1_DELETE_INTERP", "TH1_ENABLE_DOCS",
    "TH1_ENABLE_HOOKS", "TH1_ENABLE_TCL", "REMOTE_HOST",
  };
  int i;
  for(i=0; i<count(azCgiVars); i++) (void)P(azCgiVars[i]);
}

/*
** Print all query parameters on standard output.
** This is used for testing and debugging.
**
** Omit the values of the cookies unless showAll is true.
**
** The eDest parameter determines where the output is shown:
**
**     eDest==0:    Rendering as HTML into the CGI reply
**     eDest==1:    Written to stderr
**     eDest==2:    Written to cgi_debug
*/
void cgi_print_all(int showAll, unsigned int eDest){
  int i;
  cgi_parameter("","");  /* Force the parameters into sorted order */
  for(i=0; i<nUsedQP; i++){
    const char *zName = aParamQP[i].zName;
    if( !showAll ){
      if( fossil_stricmp("HTTP_COOKIE",zName)==0 ) continue;
      if( fossil_strnicmp("fossil-",zName,7)==0 ) continue;
    }
    switch( eDest ){
      case 0: {
        cgi_printf("%h = %h  <br />\n", zName, aParamQP[i].zValue);
        break;
      }
      case 1: {  
        fossil_trace("%s = %s\n", zName, aParamQP[i].zValue);
        break;
      }
      case 2: {
        cgi_debug("%s = %s\n", zName, aParamQP[i].zValue);
        break;
      }
    }
  }
}

/*
** Put information about the N-th parameter into arguments.
** Return non-zero on success, and return 0 if there is no N-th parameter.
*/
int cgi_param_info(
  int N,
  const char **pzName,
  const char **pzValue,
  int *pbIsQP
){
  if( N>=0 && N<nUsedQP ){
    *pzName = aParamQP[N].zName;
    *pzValue = aParamQP[N].zValue;
    *pbIsQP = aParamQP[N].isQP;
    return 1;
  }else{
    *pzName = 0;
    *pzValue = 0;
    *pbIsQP = 0;
    return 0;
  }
}

/*
** Export all untagged query parameters (but not cookies or environment
** variables) as hidden values of a form.
*/
void cgi_query_parameters_to_hidden(void){
  int i;
  const char *zN, *zV;
  for(i=0; i<nUsedQP; i++){
    if( aParamQP[i].isQP==0 || aParamQP[i].cTag ) continue;
    zN = aParamQP[i].zName;
    zV = aParamQP[i].zValue;
    @ <input type="hidden" name="%h(zN)" value="%h(zV)">
  }
}

/*
** Export all untagged query parameters (but not cookies or environment
** variables) to the HQuery object.
*/
void cgi_query_parameters_to_url(HQuery *p){
  int i;
  for(i=0; i<nUsedQP; i++){
    if( aParamQP[i].isQP==0 || aParamQP[i].cTag ) continue;
    url_add_parameter(p, aParamQP[i].zName, aParamQP[i].zValue);
  }
}

/*
** Tag query parameter zName so that it is not exported by
** cgi_query_parameters_to_hidden().  Or if zName==0, then
** untag all query parameters.
*/
void cgi_tag_query_parameter(const char *zName){
  int i;
  if( zName==0 ){
    for(i=0; i<nUsedQP; i++) aParamQP[i].cTag = 0;
  }else{
    for(i=0; i<nUsedQP; i++){
      if( strcmp(zName,aParamQP[i].zName)==0 ) aParamQP[i].cTag = 1;
    }
  }
}

/*
** This routine works like "printf" except that it has the
** extra formatting capabilities such as %h and %t.
*/
void cgi_printf(const char *zFormat, ...){
  va_list ap;
  va_start(ap,zFormat);
  vxprintf(pContent,zFormat,ap);
  va_end(ap);
}

/*
** This routine works like "vprintf" except that it has the
** extra formatting capabilities such as %h and %t.
*/
void cgi_vprintf(const char *zFormat, va_list ap){
  vxprintf(pContent,zFormat,ap);
}


/*
** Send a reply indicating that the HTTP request was malformed
*/
static NORETURN void malformed_request(const char *zMsg){
  cgi_set_status(501, "Not Implemented");
  cgi_printf(
    "<html><body><p>Bad Request: %s</p></body></html>\n", zMsg
  );
  cgi_reply();
  fossil_exit(0);
}

/*
** Panic and die while processing a webpage.
*/
NORETURN void cgi_panic(const char *zFormat, ...){
  va_list ap;
  cgi_reset_content();
#ifdef FOSSIL_ENABLE_JSON
  if( g.json.isJsonMode ){
    char * zMsg;
    va_start(ap, zFormat);
    zMsg = vmprintf(zFormat,ap);
    va_end(ap);
    json_err( FSL_JSON_E_PANIC, zMsg, 1 );
    free(zMsg);
    fossil_exit( g.isHTTP ? 0 : 1 );
  }else
#endif /* FOSSIL_ENABLE_JSON */
  {
    cgi_set_status(500, "Internal Server Error");
    cgi_printf(
               "<html><body><h1>Internal Server Error</h1>\n"
               "<plaintext>"
               );
    va_start(ap, zFormat);
    vxprintf(pContent,zFormat,ap);
    va_end(ap);
    cgi_reply();
    fossil_exit(1);
  }
}

/* z[] is the value of an X-FORWARDED-FOR: line in an HTTP header.
** Return a pointer to a string containing the real IP address, or a
** NULL pointer to stick with the IP address previously computed and
** loaded into g.zIpAddr.
*/
static const char *cgi_accept_forwarded_for(const char *z){
  int i;
  if( !cgi_is_loopback(g.zIpAddr) ){
    /* Only accept X-FORWARDED-FOR if input coming from the local machine */
    return 0;
  }
  i = strlen(z)-1;
  while( i>=0 && z[i]!=',' && !fossil_isspace(z[i]) ) i--;
  return &z[++i];
}

/*
** Remove the first space-delimited token from a string and return
** a pointer to it.  Add a NULL to the string to terminate the token.
** Make *zLeftOver point to the start of the next token.
*/
static char *extract_token(char *zInput, char **zLeftOver){
  char *zResult = 0;
  if( zInput==0 ){
    if( zLeftOver ) *zLeftOver = 0;
    return 0;
  }
  while( fossil_isspace(*zInput) ){ zInput++; }
  zResult = zInput;
  while( *zInput && !fossil_isspace(*zInput) ){ zInput++; }
  if( *zInput ){
    *zInput = 0;
    zInput++;
    while( fossil_isspace(*zInput) ){ zInput++; }
  }
  if( zLeftOver ){ *zLeftOver = zInput; }
  return zResult;
}

/*
** Determine the IP address on the other side of a connection.
** Return a pointer to a string.  Or return 0 if unable.
**
** The string is held in a static buffer that is overwritten on
** each call.
*/
char *cgi_remote_ip(int fd){
#if 0
  static char zIp[100];
  struct sockaddr_in6 addr;
  socklen_t sz = sizeof(addr);
  if( getpeername(fd, &addr, &sz) ) return 0;
  zIp[0] = 0;
  if( inet_ntop(AF_INET6, &addr, zIp, sizeof(zIp))==0 ){
    return 0;
  }
  return zIp;
#else
  struct sockaddr_in remoteName;
  socklen_t size = sizeof(struct sockaddr_in);
  if( getpeername(fd, (struct sockaddr*)&remoteName, &size) ) return 0;
  return inet_ntoa(remoteName.sin_addr);
#endif
}

/*
** This routine handles a single HTTP request which is coming in on
** g.httpIn and which replies on g.httpOut
**
** The HTTP request is read from g.httpIn and is used to initialize
** entries in the cgi_parameter() hash, as if those entries were
** environment variables.  A call to cgi_init() completes
** the setup.  Once all the setup is finished, this procedure returns
** and subsequent code handles the actual generation of the webpage.
*/
void cgi_handle_http_request(const char *zIpAddr){
  char *z, *zToken;
  int i;
  const char *zScheme = "http";
  char zLine[2000];     /* A single line of input. */
  g.fullHttpReply = 1;
  if( cgi_fgets(zLine, sizeof(zLine))==0 ){
    malformed_request("missing HTTP header");
  }
  blob_append(&g.httpHeader, zLine, -1);
  cgi_trace(zLine);
  zToken = extract_token(zLine, &z);
  if( zToken==0 ){
    malformed_request("malformed HTTP header");
  }
  if( fossil_strcmp(zToken,"GET")!=0
   && fossil_strcmp(zToken,"POST")!=0
   && fossil_strcmp(zToken,"HEAD")!=0
  ){
    malformed_request("unsupported HTTP method");
  }
  cgi_setenv("GATEWAY_INTERFACE","CGI/1.0");
  cgi_setenv("REQUEST_METHOD",zToken);
  zToken = extract_token(z, &z);
  if( zToken==0 ){
    malformed_request("malformed URL in HTTP header");
  }
  cgi_setenv("REQUEST_URI", zToken);
  cgi_setenv("SCRIPT_NAME", "");
  for(i=0; zToken[i] && zToken[i]!='?'; i++){}
  if( zToken[i] ) zToken[i++] = 0;
  cgi_setenv("PATH_INFO", zToken);
  cgi_setenv("QUERY_STRING", &zToken[i]);
  if( zIpAddr==0 ){
    zIpAddr = cgi_remote_ip(fileno(g.httpIn));
  }
  if( zIpAddr ){
    cgi_setenv("REMOTE_ADDR", zIpAddr);
    g.zIpAddr = fossil_strdup(zIpAddr);
  }


  /* Get all the optional fields that follow the first line.
  */
  while( cgi_fgets(zLine,sizeof(zLine)) ){
    char *zFieldName;
    char *zVal;

    cgi_trace(zLine);
    blob_append(&g.httpHeader, zLine, -1);
    zFieldName = extract_token(zLine,&zVal);
    if( zFieldName==0 || *zFieldName==0 ) break;
    while( fossil_isspace(*zVal) ){ zVal++; }
    i = strlen(zVal);
    while( i>0 && fossil_isspace(zVal[i-1]) ){ i--; }
    zVal[i] = 0;
    for(i=0; zFieldName[i]; i++){
      zFieldName[i] = fossil_tolower(zFieldName[i]);
    }
    if( fossil_strcmp(zFieldName,"accept-encoding:")==0 ){
      cgi_setenv("HTTP_ACCEPT_ENCODING", zVal);
    }else if( fossil_strcmp(zFieldName,"content-length:")==0 ){
      cgi_setenv("CONTENT_LENGTH", zVal);
    }else if( fossil_strcmp(zFieldName,"content-type:")==0 ){
      cgi_setenv("CONTENT_TYPE", zVal);
    }else if( fossil_strcmp(zFieldName,"cookie:")==0 ){
      cgi_setenv("HTTP_COOKIE", zVal);
    }else if( fossil_strcmp(zFieldName,"https:")==0 ){
      cgi_setenv("HTTPS", zVal);
      zScheme = "https";
    }else if( fossil_strcmp(zFieldName,"host:")==0 ){
      char *z;
      cgi_setenv("HTTP_HOST", zVal);
      z = strchr(zVal, ':');
      if( z ) z[0] = 0;
      cgi_setenv("SERVER_NAME", zVal);
    }else if( fossil_strcmp(zFieldName,"if-none-match:")==0 ){
      cgi_setenv("HTTP_IF_NONE_MATCH", zVal);
    }else if( fossil_strcmp(zFieldName,"if-modified-since:")==0 ){
      cgi_setenv("HTTP_IF_MODIFIED_SINCE", zVal);
    }else if( fossil_strcmp(zFieldName,"referer:")==0 ){
      cgi_setenv("HTTP_REFERER", zVal);
    }else if( fossil_strcmp(zFieldName,"user-agent:")==0 ){
      cgi_setenv("HTTP_USER_AGENT", zVal);
    }else if( fossil_strcmp(zFieldName,"authorization:")==0 ){
      cgi_setenv("HTTP_AUTHORIZATION", zVal);
    }else if( fossil_strcmp(zFieldName,"x-forwarded-for:")==0 ){
      const char *zIpAddr = cgi_accept_forwarded_for(zVal);
      if( zIpAddr!=0 ){
        g.zIpAddr = fossil_strdup(zIpAddr);
        cgi_replace_parameter("REMOTE_ADDR", g.zIpAddr);
      }
    }else if( fossil_strcmp(zFieldName,"range:")==0 ){
      int x1 = 0;
      int x2 = 0;
      if( sscanf(zVal,"bytes=%d-%d",&x1,&x2)==2 && x1>=0 && x1<=x2 ){
        rangeStart = x1;
        rangeEnd = x2+1;
      }
    }
  }
  cgi_setenv("REQUEST_SCHEME",zScheme);
  cgi_init();
  cgi_trace(0);
}

/*
** This routine handles a single HTTP request from an SSH client which is
** coming in on g.httpIn and which replies on g.httpOut
**
** Once all the setup is finished, this procedure returns
** and subsequent code handles the actual generation of the webpage.
**
** It is called in a loop so some variables will need to be replaced
*/
void cgi_handle_ssh_http_request(const char *zIpAddr){
  static int nCycles = 0;
  static char *zCmd = 0;
  char *z, *zToken;
  const char *zType = 0;
  int i, content_length = 0;
  char zLine[2000];     /* A single line of input. */

  assert( !g.httpUseSSL );
#ifdef FOSSIL_ENABLE_JSON
  if( nCycles==0 ){ json_bootstrap_early(); }
#endif
  if( zIpAddr ){
    if( nCycles==0 ){
      cgi_setenv("REMOTE_ADDR", zIpAddr);
      g.zIpAddr = fossil_strdup(zIpAddr);
    }
  }else{
    fossil_fatal("missing SSH IP address");
  }
  if( fgets(zLine, sizeof(zLine),g.httpIn)==0 ){
    malformed_request("missing HTTP header");
  }
  cgi_trace(zLine);
  zToken = extract_token(zLine, &z);
  if( zToken==0 ){
    malformed_request("malformed HTTP header");
  }

  if( fossil_strcmp(zToken, "echo")==0 ){
    /* start looking for probes to complete transport_open */
    zCmd = cgi_handle_ssh_probes(zLine, sizeof(zLine), z, zToken);
    if( fgets(zLine, sizeof(zLine),g.httpIn)==0 ){
      malformed_request("missing HTTP header");
    }
    cgi_trace(zLine);
    zToken = extract_token(zLine, &z);
    if( zToken==0 ){
      malformed_request("malformed HTTP header");
    }
  }else if( zToken && strlen(zToken)==0 && zCmd ){
    /* transport_flip request and continued transport_open */
    cgi_handle_ssh_transport(zCmd);
    if( fgets(zLine, sizeof(zLine),g.httpIn)==0 ){
      malformed_request("missing HTTP header");
    }
    cgi_trace(zLine);
    zToken = extract_token(zLine, &z);
    if( zToken==0 ){
      malformed_request("malformed HTTP header");
    }
  }

  if( fossil_strcmp(zToken,"GET")!=0 && fossil_strcmp(zToken,"POST")!=0
      && fossil_strcmp(zToken,"HEAD")!=0 ){
    malformed_request("unsupported HTTP method");
  }

  if( nCycles==0 ){
    cgi_setenv("GATEWAY_INTERFACE","CGI/1.0");
    cgi_setenv("REQUEST_METHOD",zToken);
  }

  zToken = extract_token(z, &z);
  if( zToken==0 ){
    malformed_request("malformed URL in HTTP header");
  }
  if( nCycles==0 ){
    cgi_setenv("REQUEST_URI", zToken);
    cgi_setenv("SCRIPT_NAME", "");
  }

  for(i=0; zToken[i] && zToken[i]!='?'; i++){}
  if( zToken[i] ) zToken[i++] = 0;
  if( nCycles==0 ){
    cgi_setenv("PATH_INFO", zToken);
  }else{
    cgi_replace_parameter("PATH_INFO", fossil_strdup(zToken));
  }

  /* Get all the optional fields that follow the first line.
  */
  while( fgets(zLine,sizeof(zLine),g.httpIn) ){
    char *zFieldName;
    char *zVal;

    cgi_trace(zLine);
    zFieldName = extract_token(zLine,&zVal);
    if( zFieldName==0 || *zFieldName==0 ) break;
    while( fossil_isspace(*zVal) ){ zVal++; }
    i = strlen(zVal);
    while( i>0 && fossil_isspace(zVal[i-1]) ){ i--; }
    zVal[i] = 0;
    for(i=0; zFieldName[i]; i++){
      zFieldName[i] = fossil_tolower(zFieldName[i]);
    }
    if( fossil_strcmp(zFieldName,"content-length:")==0 ){
      content_length = atoi(zVal);
    }else if( fossil_strcmp(zFieldName,"content-type:")==0 ){
      g.zContentType = zType = fossil_strdup(zVal);
    }else if( fossil_strcmp(zFieldName,"host:")==0 ){
      if( nCycles==0 ){
        cgi_setenv("HTTP_HOST", zVal);
      }
    }else if( fossil_strcmp(zFieldName,"user-agent:")==0 ){
      if( nCycles==0 ){
        cgi_setenv("HTTP_USER_AGENT", zVal);
      }
    }else if( fossil_strcmp(zFieldName,"x-fossil-transport:")==0 ){
      if( fossil_strnicmp(zVal, "ssh", 3)==0 ){
        if( nCycles==0 ){
          g.fSshClient |= CGI_SSH_FOSSIL;
          g.fullHttpReply = 0;
        }
      }
    }
  }

  if( nCycles==0 ){
    if( ! ( g.fSshClient & CGI_SSH_FOSSIL ) ){
      /* did not find new fossil ssh transport */
      g.fSshClient &= ~CGI_SSH_CLIENT;
      g.fullHttpReply = 1;
      cgi_replace_parameter("REMOTE_ADDR", "127.0.0.1");
    }
  }

  cgi_reset_content();
  cgi_destination(CGI_BODY);

  if( content_length>0 && zType ){
    blob_zero(&g.cgiIn);
    if( fossil_strcmp(zType, "application/x-fossil")==0 ){
      blob_read_from_channel(&g.cgiIn, g.httpIn, content_length);
      blob_uncompress(&g.cgiIn, &g.cgiIn);
    }else if( fossil_strcmp(zType, "application/x-fossil-debug")==0 ){
      blob_read_from_channel(&g.cgiIn, g.httpIn, content_length);
    }else if( fossil_strcmp(zType, "application/x-fossil-uncompressed")==0 ){
      blob_read_from_channel(&g.cgiIn, g.httpIn, content_length);
    }
  }
  cgi_trace(0);
  nCycles++;
}

/*
** This routine handles the old fossil SSH probes
*/
char *cgi_handle_ssh_probes(char *zLine, int zSize, char *z, char *zToken){
  /* Start looking for probes */
  assert( !g.httpUseSSL );
  while( fossil_strcmp(zToken, "echo")==0 ){
    zToken = extract_token(z, &z);
    if( zToken==0 ){
      malformed_request("malformed probe");
    }
    if( fossil_strncmp(zToken, "test", 4)==0 ||
        fossil_strncmp(zToken, "probe-", 6)==0 ){
      fprintf(g.httpOut, "%s\n", zToken);
      fflush(g.httpOut);
    }else{
      malformed_request("malformed probe");
    }
    if( fgets(zLine, zSize, g.httpIn)==0 ){
      malformed_request("malformed probe");
    }
    cgi_trace(zLine);
    zToken = extract_token(zLine, &z);
    if( zToken==0 ){
      malformed_request("malformed probe");
    }
  }

  /* Got all probes now first transport_open is completed
  ** so return the command that was requested
  */
  g.fSshClient |= CGI_SSH_COMPAT;
  return fossil_strdup(zToken);
}

/*
** This routine handles the old fossil SSH transport_flip
** and transport_open communications if detected.
*/
void cgi_handle_ssh_transport(const char *zCmd){
  char *z, *zToken;
  char zLine[2000];     /* A single line of input. */

  assert( !g.httpUseSSL );
  /* look for second newline of transport_flip */
  if( fgets(zLine, sizeof(zLine),g.httpIn)==0 ){
    malformed_request("incorrect transport_flip");
  }
  cgi_trace(zLine);
  zToken = extract_token(zLine, &z);
  if( zToken && strlen(zToken)==0 ){
    /* look for path to fossil */
    if( fgets(zLine, sizeof(zLine),g.httpIn)==0 ){
      if( zCmd==0 ){
        malformed_request("missing fossil command");
      }else{
        /* no new command so exit */
        fossil_exit(0);
      }
    }
    cgi_trace(zLine);
    zToken = extract_token(zLine, &z);
    if( zToken==0 ){
      malformed_request("malformed fossil command");
    }
    /* see if we've seen the command */
    if( zCmd && zCmd[0] && fossil_strcmp(zToken, zCmd)==0 ){
      return;
    }else{
      malformed_request("transport_open failed");
    }
  }else{
    malformed_request("transport_flip failed");
  }
}

/*
** This routine handles a single SCGI request which is coming in on
** g.httpIn and which replies on g.httpOut
**
** The SCGI request is read from g.httpIn and is used to initialize
** entries in the cgi_parameter() hash, as if those entries were
** environment variables.  A call to cgi_init() completes
** the setup.  Once all the setup is finished, this procedure returns
** and subsequent code handles the actual generation of the webpage.
*/
void cgi_handle_scgi_request(void){
  char *zHdr;
  char *zToFree;
  int nHdr = 0;
  int nRead;
  int c, n, m;

  assert( !g.httpUseSSL );
  while( (c = fgetc(g.httpIn))!=EOF && fossil_isdigit((char)c) ){
    nHdr = nHdr*10 + (char)c - '0';
  }
  if( nHdr<16 ) malformed_request("SCGI header too short");
  zToFree = zHdr = fossil_malloc(nHdr);
  nRead = (int)fread(zHdr, 1, nHdr, g.httpIn);
  if( nRead<nHdr ) malformed_request("cannot read entire SCGI header");
  nHdr = nRead;
  while( nHdr ){
    for(n=0; n<nHdr && zHdr[n]; n++){}
    for(m=n+1; m<nHdr && zHdr[m]; m++){}
    if( m>=nHdr ) malformed_request("SCGI header formatting error");
    cgi_set_parameter(zHdr, zHdr+n+1);
    zHdr += m+1;
    nHdr -= m+1;
  }
  fossil_free(zToFree);
  fgetc(g.httpIn);  /* Read past the "," separating header from content */
  cgi_init();
}


#if INTERFACE
/*
** Bitmap values for the flags parameter to cgi_http_server().
*/
#define HTTP_SERVER_LOCALHOST      0x0001     /* Bind to 127.0.0.1 only */
#define HTTP_SERVER_SCGI           0x0002     /* SCGI instead of HTTP */
#define HTTP_SERVER_HAD_REPOSITORY 0x0004     /* Was the repository open? */
#define HTTP_SERVER_HAD_CHECKOUT   0x0008     /* Was a checkout open? */
#define HTTP_SERVER_REPOLIST       0x0010     /* Allow repo listing */
#define HTTP_SERVER_NOFORK         0x0020     /* Do not call fork() */

#endif /* INTERFACE */

/*
** Maximum number of child processes that we can have running
** at one time.  Set this to 0 for "no limit".
*/
#ifndef FOSSIL_MAX_CONNECTIONS
# define FOSSIL_MAX_CONNECTIONS 1000
#endif

/*
** Implement an HTTP server daemon listening on port iPort.
**
** As new connections arrive, fork a child and let child return
** out of this procedure call.  The child will handle the request.
** The parent never returns from this procedure.
**
** Return 0 to each child as it runs.  If unable to establish a
** listening socket, return non-zero.
*/
int cgi_http_server(
  int mnPort, int mxPort,   /* Range of TCP ports to try */
  const char *zBrowser,     /* Run this browser, if not NULL */
  const char *zIpAddr,      /* Bind to this IP address, if not null */
  int flags                 /* HTTP_SERVER_* flags */
){
#if defined(_WIN32)
  /* Use win32_http_server() instead */
  fossil_exit(1);
#else
  int listener = -1;           /* The server socket */
  int connection;              /* A socket for each individual connection */
  int nRequest = 0;            /* Number of requests handled so far */
  fd_set readfds;              /* Set of file descriptors for select() */
  socklen_t lenaddr;           /* Length of the inaddr structure */
  int child;                   /* PID of the child process */
  int nchildren = 0;           /* Number of child processes */
  struct timeval delay;        /* How long to wait inside select() */
  struct sockaddr_in inaddr;   /* The socket address */
  int opt = 1;                 /* setsockopt flag */
  int iPort = mnPort;

  while( iPort<=mxPort ){
    memset(&inaddr, 0, sizeof(inaddr));
    inaddr.sin_family = AF_INET;
    if( zIpAddr ){
      inaddr.sin_addr.s_addr = inet_addr(zIpAddr);
      if( inaddr.sin_addr.s_addr == (-1) ){
        fossil_fatal("not a valid IP address: %s", zIpAddr);
      }
    }else if( flags & HTTP_SERVER_LOCALHOST ){
      inaddr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
    }else{
      inaddr.sin_addr.s_addr = htonl(INADDR_ANY);
    }
    inaddr.sin_port = htons(iPort);
    listener = socket(AF_INET, SOCK_STREAM, 0);
    if( listener<0 ){
      iPort++;
      continue;
    }

    /* if we can't terminate nicely, at least allow the socket to be reused */
    setsockopt(listener,SOL_SOCKET,SO_REUSEADDR,&opt,sizeof(opt));

    if( bind(listener, (struct sockaddr*)&inaddr, sizeof(inaddr))<0 ){
      close(listener);
      iPort++;
      continue;
    }
    break;
  }
  if( iPort>mxPort ){
    if( mnPort==mxPort ){
      fossil_fatal("unable to open listening socket on ports %d", mnPort);
    }else{
      fossil_fatal("unable to open listening socket on any"
                   " port in the range %d..%d", mnPort, mxPort);
    }
  }
  if( iPort>mxPort ) return 1;
  listen(listener,10);
  fossil_print("Listening for %s requests on TCP port %d\n",
     (flags & HTTP_SERVER_SCGI)!=0 ? "SCGI" :
        g.httpUseSSL?"TLS-encrypted HTTPS":"HTTP",  iPort);
  fflush(stdout);
  if( zBrowser ){
    assert( strstr(zBrowser,"%d")!=0 );
    zBrowser = mprintf(zBrowser /*works-like:"%d"*/, iPort);
#if defined(__CYGWIN__)
    /* On Cygwin, we can do better than "echo" */
    if( strncmp(zBrowser, "echo ", 5)==0 ){
      wchar_t *wUrl = fossil_utf8_to_unicode(zBrowser+5);
      wUrl[wcslen(wUrl)-2] = 0; /* Strip terminating " &" */
      if( (size_t)ShellExecuteW(0, L"open", wUrl, 0, 0, 1)<33 ){
        fossil_warning("cannot start browser\n");
      }
    }else
#endif
    if( fossil_system(zBrowser)<0 ){
      fossil_warning("cannot start browser: %s\n", zBrowser);
    }
  }
  while( 1 ){
#if FOSSIL_MAX_CONNECTIONS>0
    while( nchildren>=FOSSIL_MAX_CONNECTIONS ){
      if( wait(0)>=0 ) nchildren--;
    }
#endif
    delay.tv_sec = 0;
    delay.tv_usec = 100000;
    FD_ZERO(&readfds);
    assert( listener>=0 );
    FD_SET( listener, &readfds);
    select( listener+1, &readfds, 0, 0, &delay);
    if( FD_ISSET(listener, &readfds) ){
      lenaddr = sizeof(inaddr);
      connection = accept(listener, (struct sockaddr*)&inaddr, &lenaddr);
      if( connection>=0 ){
        if( flags & HTTP_SERVER_NOFORK ){
          child = 0;
        }else{
          child = fork();
        }
        if( child!=0 ){
          if( child>0 ){
            nchildren++;
            nRequest++;
          }
          close(connection);
        }else{
          int nErr = 0, fd;
          close(0);
          fd = dup(connection);
          if( fd!=0 ) nErr++;
          close(1);
          fd = dup(connection);
          if( fd!=1 ) nErr++;
          if( 0 && !g.fAnyTrace ){
            close(2);
            fd = dup(connection);
            if( fd!=2 ) nErr++;
          }
          close(connection);
          g.nPendingRequest = nchildren+1;
          g.nRequest = nRequest+1;
          return nErr;
        }
      }
    }
    /* Bury dead children */
    if( nchildren ){
      while(1){
        int iStatus = 0;
        pid_t x = waitpid(-1, &iStatus, WNOHANG);
        if( x<=0 ) break;
        if( WIFSIGNALED(iStatus) && g.fAnyTrace ){
          fprintf(stderr, "/***** Child %d exited on signal %d (%s) *****/\n",
                  x, WTERMSIG(iStatus), strsignal(WTERMSIG(iStatus)));
        }
        nchildren--;
      }
    }
  }
  /* NOT REACHED */
  fossil_exit(1);
#endif
  /* NOT REACHED */
  return 0;
}


/*
** Name of days and months.
*/
static const char *const azDays[] =
    {"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat", 0};
static const char *const azMonths[] =
    {"Jan", "Feb", "Mar", "Apr", "May", "Jun",
     "Jul", "Aug", "Sep", "Oct", "Nov", "Dec", 0};


/*
** Returns an RFC822-formatted time string suitable for HTTP headers.
** The timezone is always GMT.  The value returned is always a
** string obtained from mprintf() and must be freed using fossil_free()
** to avoid a memory leak.
**
** See http://www.faqs.org/rfcs/rfc822.html, section 5
** and http://www.faqs.org/rfcs/rfc2616.html, section 3.3.
*/
char *cgi_rfc822_datestamp(time_t now){
  struct tm *pTm;
  pTm = gmtime(&now);
  if( pTm==0 ){
    return mprintf("");
  }else{
    return mprintf("%s, %d %s %02d %02d:%02d:%02d +0000",
                   azDays[pTm->tm_wday], pTm->tm_mday, azMonths[pTm->tm_mon],
                   pTm->tm_year+1900, pTm->tm_hour, pTm->tm_min, pTm->tm_sec);
  }
}

/*
** Returns an ISO8601-formatted time string suitable for debugging
** purposes.
**
** The value returned is always a string obtained from mprintf() and must
** be freed using fossil_free() to avoid a memory leak.
*/
char *cgi_iso8601_datestamp(void){
  struct tm *pTm;
  time_t now = time(0);
  pTm = gmtime(&now);
  if( pTm==0 ){
    return mprintf("");
  }else{
    return mprintf("%04d-%02d-%02d %02d:%02d:%02d",
                   pTm->tm_year+1900, pTm->tm_mon+1, pTm->tm_mday,
                   pTm->tm_hour, pTm->tm_min, pTm->tm_sec);
  }
}

/*
** COMMAND: test-date
**
** Show the current date and time in both RFC822 and ISO8601.
*/
void test_date(void){
  fossil_print("%z = ", cgi_iso8601_datestamp());
  fossil_print("%z\n", cgi_rfc822_datestamp(time(0)));
}

/*
** Parse an RFC822-formatted timestamp as we'd expect from HTTP and return
** a Unix epoch time. <= zero is returned on failure.
**
** Note that this won't handle all the _allowed_ HTTP formats, just the
** most popular one (the one generated by cgi_rfc822_datestamp(), actually).
*/
time_t cgi_rfc822_parsedate(const char *zDate){
  int mday, mon, year, yday, hour, min, sec;
  char zIgnore[4];
  char zMonth[4];
  static const char *const azMonths[] =
    {"Jan", "Feb", "Mar", "Apr", "May", "Jun",
     "Jul", "Aug", "Sep", "Oct", "Nov", "Dec", 0};
  if( 7==sscanf(zDate, "%3[A-Za-z], %d %3[A-Za-z] %d %d:%d:%d", zIgnore,
                       &mday, zMonth, &year, &hour, &min, &sec)){
    if( year > 1900 ) year -= 1900;
    for(mon=0; azMonths[mon]; mon++){
      if( !strncmp( azMonths[mon], zMonth, 3 )){
        int nDay;
        int isLeapYr;
        static int priorDays[] =
         {  0, 31, 59, 90,120,151,181,212,243,273,304,334 };
        if( mon<0 ){
          int nYear = (11 - mon)/12;
          year -= nYear;
          mon += nYear*12;
        }else if( mon>11 ){
          year += mon/12;
          mon %= 12;
        }
        isLeapYr = year%4==0 && (year%100!=0 || (year+300)%400==0);
        yday = priorDays[mon] + mday - 1;
        if( isLeapYr && mon>1 ) yday++;
        nDay = (year-70)*365 + (year-69)/4 - year/100 + (year+300)/400 + yday;
        return ((time_t)(nDay*24 + hour)*60 + min)*60 + sec;
      }
    }
  }
  return 0;
}

/*
** Check the objectTime against the If-Modified-Since request header. If the
** object time isn't any newer than the header, we immediately send back
** a 304 reply and exit.
*/
void cgi_modified_since(time_t objectTime){
  const char *zIf = P("HTTP_IF_MODIFIED_SINCE");
  if( zIf==0 ) return;
  if( objectTime > cgi_rfc822_parsedate(zIf) ) return;
  cgi_set_status(304,"Not Modified");
  cgi_reset_content();
  cgi_reply();
  fossil_exit(0);
}

/*
** Check to see if the remote client is SSH and return
** its IP or return default
*/
const char *cgi_ssh_remote_addr(const char *zDefault){
  char *zIndex;
  const char *zSshConn = fossil_getenv("SSH_CONNECTION");

  if( zSshConn && zSshConn[0] ){
    char *zSshClient = fossil_strdup(zSshConn);
    if( (zIndex = strchr(zSshClient,' '))!=0 ){
      zSshClient[zIndex-zSshClient] = '\0';
      return zSshClient;
    }
  }
  return zDefault;
}

/*
** Return true if information is coming from the loopback network.
*/
int cgi_is_loopback(const char *zIpAddr){
  return fossil_strcmp(zIpAddr, "127.0.0.1")==0 ||
         fossil_strcmp(zIpAddr, "::ffff:127.0.0.1")==0 ||
         fossil_strcmp(zIpAddr, "::1")==0;
}

/*
** Return true if the HTTP request is likely to be from a small-screen
** mobile device.
**
** The returned value is a guess.  Use it only for setting up defaults.
*/
int cgi_from_mobile(void){
  const char *zAgent = P("HTTP_USER_AGENT");
  if( zAgent==0 ) return 0;
  if( sqlite3_strglob("*iPad*", zAgent)==0 ) return 0;
  return sqlite3_strlike("%mobile%", zAgent, 0)==0;
}