if( zGoto ){
    cgi_redirect(zGoto);
  }else{
    fossil_redirect_home();
  }
}

/*
** The IP address of the client is stored as part of login cookies.
** But some clients are behind firewalls that shift the IP address
** with each HTTP request.  To allow such (broken) clients to log in,
** extract just a prefix of the IP address.
*/
static char *ipPrefix(const char *zIP){
  int i, j;
  static int ip_prefix_terms = -1;
  if( ip_prefix_terms<0 ){
    if( db_get_int("redirect-to-https",0)>=2 ){
      ip_prefix_terms = 0;
    }else{
      ip_prefix_terms = db_get_int("ip-prefix-terms",2);
    }
  }
  if( ip_prefix_terms==0 ) return mprintf("0");
  for(i=j=0; zIP[i]; i++){
    if( zIP[i]=='.' ){
      j++;
      if( j==ip_prefix_terms ) break;
    }
  }
  return mprintf("%.*s", i, zIP);
}

/*
** Return an abbreviated project code.  The abbreviation is the first
** 16 characters of the project code.
**
** Memory is obtained from malloc.
*/
static char *abbreviated_project_code(const char *zFullCode){

){
  const char *zCookieName = login_cookie_name();
  const char *zExpire = db_get("cookie-expire","8766");
  int expires = atoi(zExpire)*3600;
  char *zHash;
  char *zCookie;
  const char *zIpAddr = PD("REMOTE_ADDR","nil"); /* IP address of user */
  char *zRemoteAddr = ipPrefix(zIpAddr);         /* Abbreviated IP address */

  assert((zUsername && *zUsername) && (uid > 0) && "Invalid user data.");
  zHash = db_text(0,
      "SELECT cookie FROM user"
      " WHERE uid=%d"
      "   AND ipaddr=%Q"
      "   AND cexpire>julianday('now')"
      "   AND length(cookie)>30",
      uid, zRemoteAddr);
  if( zHash==0 ) zHash = db_text(0, "SELECT hex(randomblob(25))");
  zCookie = login_gen_user_cookie_value(zUsername, zHash);
  cgi_set_cookie(zCookieName, zCookie, login_cookie_path(), expires);
  record_login_attempt(zUsername, zIpAddr, 1);
  db_multi_exec(
                "UPDATE user SET cookie=%Q, ipaddr=%Q, "
                "  cexpire=julianday('now')+%d/86400.0 WHERE uid=%d",
                zHash, zRemoteAddr, expires, uid
                );
  free(zRemoteAddr);
  free(zHash);
  if( zDest ){
    *zDest = zCookie;
  }else{
    free(zCookie);
  }
}

/* Sets a cookie for an anonymous user login, which looks like this:
**
**    HASH/TIME/anonymous
**
** Where HASH is the sha1sum of TIME/IPADDR/SECRET, in which IPADDR
** is the abbreviated IP address and SECRET is captcha-secret.
**
** If either zIpAddr or zRemoteAddr are NULL then REMOTE_ADDR
** is used.
**
** If zCookieDest is not NULL then the generated cookie is assigned to
** *zCookieDest and the caller must eventually free() it.
*/
void login_set_anon_cookie(const char *zIpAddr, char **zCookieDest ){
  const char *zNow;            /* Current time (julian day number) */
  char *zCookie;               /* The login cookie */
  const char *zCookieName;     /* Name of the login cookie */
  Blob b;                      /* Blob used during cookie construction */
  char *zRemoteAddr;           /* Abbreviated IP address */
  if(!zIpAddr){
    zIpAddr = PD("REMOTE_ADDR","nil");
  }
  zRemoteAddr = ipPrefix(zIpAddr);
  zCookieName = login_cookie_name();
  zNow = db_text("0", "SELECT julianday('now')");
  assert( zCookieName && zRemoteAddr && zIpAddr && zNow );
  blob_init(&b, zNow, -1);
  blob_appendf(&b, "/%s/%s", zRemoteAddr, db_get("captcha-secret",""));
  sha1sum_blob(&b, &b);
  zCookie = mprintf("%s/%s/anonymous", blob_buffer(&b), zNow);
  blob_reset(&b);
  cgi_set_cookie(zCookieName, zCookie, login_cookie_path(), 6*3600);
  if( zCookieDest ){
    *zCookieDest = zCookie;
  }else{

** repository.
**
** Return true if a transfer was made and false if not.
*/
static int login_transfer_credentials(
  const char *zLogin,          /* Login we are looking for */
  const char *zCode,           /* Project code of peer repository */
  const char *zHash,           /* HASH from login cookie HASH/CODE/LOGIN */
  const char *zRemoteAddr      /* Request comes from here */
){
  sqlite3 *pOther = 0;         /* The other repository */
  sqlite3_stmt *pStmt;         /* Query against the other repository */
  char *zSQL;                  /* SQL of the query against other repo */
  char *zOtherRepo;            /* Filename of the other repository */
  int rc;                      /* Result code from SQLite library functions */
  int nXfer = 0;               /* Number of credentials transferred */

    sqlite3_create_function(pOther,"now",0,SQLITE_UTF8,0,db_now_function,0,0);
    sqlite3_create_function(pOther, "constant_time_cmp", 2, SQLITE_UTF8, 0,
                  constant_time_cmp_function, 0, 0);
    sqlite3_busy_timeout(pOther, 5000);
    zSQL = mprintf(
      "SELECT cexpire FROM user"
      " WHERE login=%Q"
      "   AND ipaddr=%Q"
      "   AND length(cap)>0"
      "   AND length(pw)>0"
      "   AND cexpire>julianday('now')"
      "   AND constant_time_cmp(cookie,%Q)=0",
      zLogin, zRemoteAddr, zHash
    );
    pStmt = 0;
    rc = sqlite3_prepare_v2(pOther, zSQL, -1, &pStmt, 0);
    if( rc==SQLITE_OK && sqlite3_step(pStmt)==SQLITE_ROW ){
      db_multi_exec(
        "UPDATE user SET cookie=%Q, ipaddr=%Q, cexpire=%.17g"
        " WHERE login=%Q",
        zHash, zRemoteAddr,
        sqlite3_column_double(pStmt, 0), zLogin
      );
      nXfer++;
    }
    sqlite3_finalize(pStmt);
  }
  sqlite3_close(pOther);

  if( fossil_strcmp(zLogin, "nobody")==0 ) return 1;
  if( fossil_strcmp(zLogin, "developer")==0 ) return 1;
  if( fossil_strcmp(zLogin, "reader")==0 ) return 1;
  return 0;
}

/*
** Lookup the uid for a non-built-in user with zLogin and zCookie and
** zRemoteAddr.  Return 0 if not found.
**
** Note that this only searches for logged-in entries with matching
** zCookie (db: user.cookie) and zRemoteAddr (db: user.ipaddr)
** entries.
*/
static int login_find_user(
  const char *zLogin,            /* User name */
  const char *zCookie,           /* Login cookie value */
  const char *zRemoteAddr        /* Abbreviated IP address for valid login */
){
  int uid;
  if( login_is_special(zLogin) ) return 0;
  uid = db_int(0,
    "SELECT uid FROM user"
    " WHERE login=%Q"
    "   AND ipaddr=%Q"
    "   AND cexpire>julianday('now')"
    "   AND length(cap)>0"
    "   AND length(pw)>0"
    "   AND constant_time_cmp(cookie,%Q)=0",
    zLogin, zRemoteAddr, zCookie
  );
  return uid;
}

/*
** Attempt to use Basic Authentication to establish the user.  Return the
** (non-zero) uid if successful.  Return 0 if it does not work.

**    g.isHuman      True if the user is human, not a spider or robot
**
*/
void login_check_credentials(void){
  int uid = 0;                  /* User id */
  const char *zCookie;          /* Text of the login cookie */
  const char *zIpAddr;          /* Raw IP address of the requestor */
  char *zRemoteAddr;            /* Abbreviated IP address of the requestor */
  const char *zCap = 0;         /* Capability string */
  const char *zPublicPages = 0; /* GLOB patterns of public pages */
  const char *zLogin = 0;       /* Login user for credentials */

  /* Only run this check once.  */
  if( g.userUid!=0 ) return;

  sqlite3_create_function(g.db, "constant_time_cmp", 2, SQLITE_UTF8, 0,
                  constant_time_cmp_function, 0, 0);

  /* If the HTTP connection is coming over 127.0.0.1 and if
  ** local login is disabled and if we are using HTTP and not HTTPS,
  ** then there is no need to check user credentials.
  **
  ** This feature allows the "fossil ui" command to give the user
  ** full access rights without having to log in.
  */
  zRemoteAddr = ipPrefix(zIpAddr = PD("REMOTE_ADDR","nil"));
  if( ( cgi_is_loopback(zIpAddr)
       || (g.fSshClient & CGI_SSH_CLIENT)!=0 )
   && g.useLocalauth
   && db_get_int("localauth",0)==0
   && P("HTTPS")==0
  ){
    if( g.localOpen ) zLogin = db_lget("default-user",0);

      /* Cookies of the form "HASH/TIME/anonymous".  The TIME must not be
      ** too old and the sha1 hash of TIME/IPADDR/SECRET must match HASH.
      ** SECRET is the "captcha-secret" value in the repository.
      */
      double rTime = atof(zArg);
      Blob b;
      blob_zero(&b);
      blob_appendf(&b, "%s/%s/%s",
                   zArg, zRemoteAddr, db_get("captcha-secret",""));
      sha1sum_blob(&b, &b);
      if( fossil_strcmp(zHash, blob_str(&b))==0 ){
        uid = db_int(0,
            "SELECT uid FROM user WHERE login='anonymous'"
            " AND length(cap)>0"
            " AND length(pw)>0"
            " AND %.17g+0.25>julianday('now')",
            rTime
        );
      }
      blob_reset(&b);
    }else{
      /* Cookies of the form "HASH/CODE/USER".  Search first in the
      ** local user table, then the user table for project CODE if we
      ** are part of a login-group.
      */
      uid = login_find_user(zUser, zHash, zRemoteAddr);
      if( uid==0 && login_transfer_credentials(zUser,zArg,zHash,zRemoteAddr) ){
        uid = login_find_user(zUser, zHash, zRemoteAddr);
        if( uid ) record_login_attempt(zUser, zIpAddr, 1);
      }
    }
    sqlite3_snprintf(sizeof(g.zCsrfToken), g.zCsrfToken, "%.10s", zHash);
  }

  /* If no user found and the REMOTE_USER environment variable is set,

     "http_authentication_ok", "http_authentication_ok", 0, 0);
  @ <p>When enabled, allow the use of the HTTP_AUTHENTICATION environment
  @ variable or the "Authentication:" HTTP header to find the username and
  @ password. This is another way of supporting Basic Authenitication.
  @ (Property: "http_authentication_ok")
  @ </p>
  @
  @ <hr />
  entry_attribute("IP address terms used in login cookie", 3,
                  "ip-prefix-terms", "ipt", "2", 0);
  @ <p>The number of octets of of the IP address used in the login cookie
  @ when using unencrypted HTTP instead of HTTPS.
  @ Set to zero to omit the IP address from the login cookie.  A value of
  @ 2 is recommended.
  @ If the "Redirect to HTTP" above is set to "Always", then the IP address
  @ is not used in the login cookie and this setting is irrelevant.
  @ (Property: "ip-prefix-terms")
  @ </p>
  @
  @ <hr />
  entry_attribute("Login expiration time", 6, "cookie-expire", "cex",
                  "8766", 0);
  @ <p>The number of hours for which a login is valid.  This must be a
  @ positive number.  The default is 8766 hours which is approximately equal
  @ to a year.
  @ (Property: "cookie-expire")</p>