/* Copyright 1999-2004 The Apache Software Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/*
 * http_auth: authentication
 * 
 * Rob McCool
 * 
 * Adapted to Apache by rst.
 *
 * dirkx - Added Authoritative control to allow passing on to lower
 *         modules if and only if the userid is not known to this
 *         module. A known user with a faulty or absent password still
 *         causes an AuthRequired. The default is 'Authoritative', i.e.
 *         no control is passed along.
 */

#include <fcntl.h>
#include "apr_strings.h"
#include "apr_md5.h"            /* for apr_password_validate */

#include "ap_config.h"
#include "httpd.h"
#include "http_config.h"
#include "http_core.h"
#include "http_log.h"
#include "http_protocol.h"
#include "http_request.h"


typedef struct {
    char *auth_pwfile;
    char *auth_pwcontrol;
    char *auth_grpfile;
    int auth_authoritative;
} auth_config_rec;

void ap_to64(char *s, unsigned long v, int n)
{
    static unsigned char itoa64[] =         /* 0 ... 63 => ASCII - 64 */
        "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";

    while (--n >= 0) {
        *s++ = itoa64[v&0x3f];
        v >>= 6;
    }
}

static void *create_auth_dir_config(apr_pool_t *p, char *d)
{
    auth_config_rec *conf = apr_palloc(p, sizeof(*conf));

    conf->auth_pwfile = NULL;     /* just to illustrate the default really */
    conf->auth_pwcontrol = NULL;     /* just to illustrate the default really */
    conf->auth_grpfile = NULL;    /* unless you have a broken HP cc */
    conf->auth_authoritative = 1; /* keep the fortress secure by default */
    return conf;
}

static const char *set_auth_slot(cmd_parms *cmd, void *offset, const char *f, 
                                 const char *t)
{
    if (t && strcmp(t, "standard")) {
        return apr_pstrcat(cmd->pool, "Invalid auth file type: ", t, NULL);
    }

    return ap_set_file_slot(cmd, offset, f);
}

static const command_rec auth_cmds[] =
{
    AP_INIT_TAKE12("AuthUserFile", set_auth_slot,
                   (void *)APR_OFFSETOF(auth_config_rec, auth_pwfile),
                   OR_AUTHCFG, "text file containing user IDs and passwords"),
    AP_INIT_TAKE12("AuthUserControl", set_auth_slot,
                (void *)APR_OFFSETOF(auth_config_rec, auth_pwcontrol),
                   OR_AUTHCFG, 
                 "password control: /Traditional, /Ignore, /Confirm, /Approve"),
    AP_INIT_TAKE12("AuthGroupFile", set_auth_slot,
                   (void *)APR_OFFSETOF(auth_config_rec, auth_grpfile),
                   OR_AUTHCFG,
                   "text file containing group names and member user IDs"),
    AP_INIT_FLAG("AuthAuthoritative", ap_set_flag_slot,
                 (void *)APR_OFFSETOF(auth_config_rec, auth_authoritative),
                 OR_AUTHCFG,
                 "Set to 'no' to allow access control to be passed along to "
                 "lower modules if the UserID is not known to this module"),
    {NULL}
};

module AP_MODULE_DECLARE_DATA auth_module;

static char *get_pw
   (request_rec *r, char *user, char *auth_pwfile, char *auth_pwcontrol, 
   char *sent_pw) /*extra params for pw_control /Confirm or /Approve */
{
    ap_configfile_t *f;
    char l[MAX_STRING_LEN];
    const char *rpw, *w;
    char *retval = NULL;
    apr_status_t status;
    /* following are for auth_pwcontrol /Confirm or /Approve */
    char *foundpw = NULL;
    char *controlflag = NULL;
    int user_found = -1;
    int pw_matched = 0;
    #define MAX_LINES 256
    char buffer[MAX_LINES*MAX_STRING_LEN];
    int buffersize = MAX_LINES*MAX_STRING_LEN; 
    int nbytes = 0;
    int i;
    char cpw[120];
    char salt[9];


    int fd = open(auth_pwfile, O_RDWR);

    if (fd < 0) {
    } else {
        if (flock(fd, LOCK_SH) < 0) {
        }
    }

    
    if (!auth_pwcontrol ||
        !strcasecmp(auth_pwcontrol,"/Ignore") ||
        !strcasecmp(auth_pwcontrol,"/Traditional")) {

        if ((status = 
                   ap_pcfg_openfile(&f, r->pool, auth_pwfile)) != APR_SUCCESS) {
            ap_log_rerror(APLOG_MARK, APLOG_ERR, status, r,
                          "Could not open password file: %s", auth_pwfile);
            close(fd);

            return NULL;
        }
        retval = malloc(MAX_STRING_LEN);
        while (!(ap_cfg_getline(l, MAX_STRING_LEN, f))) {
            if ((l[0] == '#') || (!l[0])) {
                continue;
            }
            rpw = l;
            w = ap_getword(r->pool, &rpw, ':');
    
            if (!strcmp(user, w)) {
                ap_cfg_closefile(f);
                close(fd);
                strcpy(retval, ap_getword(r->pool, &rpw, ':'));
                strcat(retval, ":");
                strcat(retval, ap_getword(r->pool, &rpw, ':'));

                return retval;
            }
        }
        ap_cfg_closefile(f);
    
        close(fd);
    

        return NULL;
    } else {

        if ((status = 
                   ap_pcfg_openfile(&f, r->pool, auth_pwfile)) != APR_SUCCESS) {
            ap_log_rerror(APLOG_MARK, APLOG_ERR, status, r,
                          "Could not open password file: %s", auth_pwfile);
            close(fd);

            return NULL;
        }
        retval = malloc(MAX_STRING_LEN);
        while (!(ap_cfg_getline(l, MAX_STRING_LEN, f)) && 
                (nbytes < buffersize-MAX_STRING_LEN)) {
            if ((l[0] == '#') || (!l[0])) {
                continue;
            }
            rpw = l;
            w = ap_getword(r->pool, &rpw, ':');
    
            if (!strcmp(user, w)) {

                user_found = 1;
                foundpw = ap_getword(r->pool, &rpw, ':');

                strcpy(retval, foundpw);
                strcat(retval, ":");
                controlflag = ap_getword(r->pool, &rpw, ':');
                strcat(retval, controlflag);

                /*
                 /Confirm uses "Initial" and then "Confirm"
                 /Approve uses "Request" and then "Approve"
                */
                if ((!strcasecmp(controlflag,"Initial")) ||
                    (!strcasecmp(controlflag,"Request"))) {
                    if (apr_password_validate(sent_pw, foundpw)!=APR_SUCCESS) {
                        user_found = 0;
                        pw_matched = 0;
                    } else {
                        pw_matched = 1;
                    }

                }
            } else {
                i = -1;
                while ((i < MAX_STRING_LEN) && l[++i]) {
                    buffer[nbytes++] = l[i];
                }
                if (l[i]) {
                    buffer[nbytes++] = l[i];
		} else {
                    buffer[nbytes++] = '\n';
		}
            }
        }

        ap_cfg_closefile(f);
        if (user_found && pw_matched) {

            /* user's entry should be finalized */
            buffer[nbytes-1] = '\n';
            strcat(&buffer[nbytes],user);
            nbytes+=strlen(user);
            strcat(&buffer[nbytes++],":");
            strcpy(retval, foundpw);
            if (!strcasecmp(auth_pwcontrol,"/Approve")) {
                strcat(retval, ":Approve");
            } else {
                strcat(retval, ":");
            }
            strcat(&buffer[nbytes],retval);
            nbytes+=strlen(retval);
            strcat(&buffer[nbytes++],"\n");
            ftruncate(fd,0);
            lseek(fd,0,SEEK_SET);
            write(fd,buffer,nbytes);
            fsync(fd);
            close(fd);

        } else {
            if (user_found) {

                /* user's entry should be initialized */
                buffer[nbytes-1] = '\n';
                strcat(&buffer[nbytes],user);
                nbytes+=strlen(user);
                strcat(&buffer[nbytes++],":");
                /*need to crypt here*/
                (void) srand((int) time((time_t *) NULL));
                ap_to64(&salt[0], rand(), 8);
                salt[8] = '\0';

                strncpy(cpw, (char *)crypt(sent_pw, salt), sizeof(cpw) - 1);
                strcpy(retval, cpw);
                if (!strcasecmp(auth_pwcontrol,"/Confirm")) {
                    strcat(retval, ":Initial");
                    strcat(&buffer[nbytes],retval);
                    nbytes+=strlen(retval);
                    strcat(&buffer[nbytes++],"\n");
                } else {
                if (!strcasecmp(auth_pwcontrol,"/Approve")) {
                    strcat(retval, ":Request");
                    strcat(&buffer[nbytes],retval);
                    nbytes+=strlen(retval);
                    strcat(&buffer[nbytes++],"\n");
                }
                }
                ftruncate(fd,0);
                lseek(fd,0,SEEK_SET);
                write(fd,buffer,nbytes);
                fsync(fd);
                close(fd);

            } else {

            }
        }
    }
    
    close(fd);
    

    return retval;
}

static apr_table_t *groups_for_user(apr_pool_t *p, char *user, char *grpfile)
{
    ap_configfile_t *f;
    apr_table_t *grps = apr_table_make(p, 15);
    apr_pool_t *sp;
    char l[MAX_STRING_LEN];
    const char *group_name, *ll, *w;
    apr_status_t status;

    if ((status = ap_pcfg_openfile(&f, p, grpfile)) != APR_SUCCESS) {
/*add?  aplog_error(APLOG_MARK, APLOG_ERR, NULL,
                    "Could not open group file: %s", grpfile);*/
        return NULL;
    }

    apr_pool_create(&sp, p);

    while (!(ap_cfg_getline(l, MAX_STRING_LEN, f))) {
        if ((l[0] == '#') || (!l[0])) {
            continue;
        }
        ll = l;
        apr_pool_clear(sp);

        group_name = ap_getword(sp, &ll, ':');

        while (ll[0]) {
            w = ap_getword_conf(sp, &ll);
            if (!strcmp(w, user)) {
                apr_table_setn(grps, apr_pstrdup(p, group_name), "in");
                break;
            }
        }
    }
    ap_cfg_closefile(f);
    apr_pool_destroy(sp);
    return grps;
}

/* These functions return 0 if client is OK, and proper error status
 * if not... either HTTP_UNAUTHORIZED, if we made a check, and it failed, or
 * HTTP_INTERNAL_SERVER_ERROR, if things are so totally confused that we
 * couldn't figure out how to tell if the client is authorized or not.
 *
 * If they return DECLINED, and all other modules also decline, that's
 * treated by the server core as a configuration error, logged and
 * reported as such.
 */

/* Determine user ID, and check if it really is that user, for HTTP
 * basic authentication...
 */

static int authenticate_basic_user(request_rec *r)
{
    ap_configfile_t *f;
    apr_status_t status;
    auth_config_rec *conf = ap_get_module_config(r->per_dir_config,
                                                 &auth_module);
    const char *sent_pw;
    char *user_pw;
    char *real_pw;
    apr_status_t invalid_pw;
    int res;
    char l[MAX_STRING_LEN];
    const char *afterpw;

  if (!conf->auth_pwcontrol ||
      !strcasecmp(conf->auth_pwcontrol,"/Traditional")) {


    if ((res = ap_get_basic_auth_pw(r, &sent_pw))) {
        return res;
    }

    /*if (strlen(sent_pw) < 3) {
        return DECLINED;
    }*/

    if (!conf->auth_pwfile) {
        return DECLINED;
    }

    if (!(real_pw = get_pw
              (r, r->user, conf->auth_pwfile, conf->auth_pwcontrol, NULL))) {
        if (!(conf->auth_authoritative)) {
            return DECLINED;
        }
        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                      "user %s not found: %s", r->user, r->uri);
        ap_note_basic_auth_failure(r);
        return HTTP_UNAUTHORIZED;
    }
    strcpy(&l[0],real_pw);
    afterpw = l;
    strcpy(real_pw, ap_getword(r->pool, &afterpw, ':'));
    invalid_pw = apr_password_validate(sent_pw, real_pw);
    if (invalid_pw != APR_SUCCESS) {
        user_pw = malloc(strlen(conf->auth_pwcontrol)+1+strlen(r->user)+strlen(sent_pw)+strlen(real_pw)+3);
        strcpy(user_pw,conf->auth_pwcontrol);
        strcat(user_pw,":");
        strcat(user_pw,r->user);

        strcat(user_pw,":");
        strcat(user_pw,real_pw);
        strncpy(r->user,user_pw,MAX_STRING_LEN); 
        free(user_pw);
        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                      "control:user:pw %s: authentication failure for \"%s\": "
                      "Password Mismatch",
                      r->user, r->uri);
        ap_note_basic_auth_failure(r);
        free(real_pw); /* this should work in spite of ap_getword call above */
        return HTTP_UNAUTHORIZED;
    }
    free(real_pw); /* this should work in spite of ap_getword call above */
    if (!strcasecmp(afterpw,"Approve")) {
        return HTTP_UNAUTHORIZED;
    } else {
        return OK;
    }

  } else {

    if (!strcasecmp(conf->auth_pwcontrol,"/Ignore")) {
        /*Much of this is lifted from ap_get_basic_auth_pw()*/
        const char *auth_line = apr_table_get(r->headers_in,
                                          (PROXYREQ_PROXY == r->proxyreq)
                                              ? "Proxy-Authorization"
                                              : "Authorization");
        const char *t;
        if (!auth_line) {
            ap_note_basic_auth_failure(r);
            return HTTP_UNAUTHORIZED;
        }
        if (strcasecmp(ap_getword(r->pool, &auth_line, ' '), "Basic")) {
            /* Client tried to authenticate using wrong auth scheme */
            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                      "client used wrong authentication scheme: %s", r->uri);
            ap_note_basic_auth_failure(r);
            return HTTP_UNAUTHORIZED;
        }
        while (*auth_line == ' ' || *auth_line == '\t') {
            auth_line++;
        }
        t = ap_pbase64decode(r->pool, auth_line);
        r->user = ap_getword_nulls (r->pool, &t, ':');
        r->ap_auth_type = "Basic";
        /* does this look like an email address ? */
        if ((strlen(r->user) > 3) &&
            (strpbrk("@@", r->user) != NULL) &&
            (strpbrk(".", r->user) != NULL)) {
            return OK;
        } else {
            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                      "client gave inadequate User Name");
            ap_note_basic_auth_failure(r);
            return HTTP_UNAUTHORIZED;
        }

    } else {


      /* Both /Confirm and /Approve cases are two-steps:
         /Confirm uses "Initial" and then "Confirm"
         /Approve uses "Request" and then "Approve"
         Note that these "flags" are the same length, allowing
         get_pw a little easier time of things.
      */
      if (!strcasecmp(conf->auth_pwcontrol,"/Confirm") ||
          !strcasecmp(conf->auth_pwcontrol,"/Approve")) {


          if ((res = ap_get_basic_auth_pw(r, &sent_pw))) {
             return res;
          }

          if (!conf->auth_pwfile) {
              return DECLINED;
          }


          strcpy(&l[0],sent_pw);
          user_pw = l;
          if (!(real_pw = get_pw
             (r, r->user, conf->auth_pwfile, conf->auth_pwcontrol, user_pw))) {
              if (!(conf->auth_authoritative)) {
                  return DECLINED;
              }
              ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                            "user %s not found: %s", r->user, r->uri);
              ap_note_basic_auth_failure(r);
              return HTTP_UNAUTHORIZED;
          }
          strcpy(&l[0],real_pw);
          afterpw = l;
          strcpy(real_pw, ap_getword(r->pool, &afterpw, ':'));
          invalid_pw = apr_password_validate(sent_pw, real_pw);
          if (invalid_pw != APR_SUCCESS) {
              user_pw = malloc(strlen(conf->auth_pwcontrol)+1+strlen(r->user)
                               +strlen(sent_pw)+strlen(real_pw)+3);
              strcpy(user_pw,conf->auth_pwcontrol);
              strcat(user_pw,":");
              strcat(user_pw,r->user);

              strcat(user_pw,":");
              strcat(user_pw,real_pw);
              strncpy(r->user,user_pw,MAX_STRING_LEN); 
              free(user_pw);
              ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                    "control:user:pw %s: authentication failure for \"%s\": "
                    "Password Mismatch",
                    r->user, r->uri);
              ap_note_basic_auth_failure(r);
              free(real_pw); /* should work despite ap_getword call above */
              return HTTP_UNAUTHORIZED;
          }
          free(real_pw); /* this should work despite ap_getword call above */
	  if ((!strcasecmp(conf->auth_pwcontrol,"/Approve")) && 
	      (!strcasecmp(afterpw,"Approve"))) {
              return OK; /*was HTTP_UNAUTHORIZED*/
	  } else {
              return OK;
	  }
      }
    }
  }
  ap_note_basic_auth_failure(r);
  return HTTP_UNAUTHORIZED;
}

/* Checking ID */

static int check_user_access(request_rec *r)
{
    auth_config_rec *conf = ap_get_module_config(r->per_dir_config,
                                                 &auth_module);
    char *user = r->user;
    int m = r->method_number;
    int method_restricted = 0;
    register int x;
    const char *t, *w;
    apr_table_t *grpstatus;
    const apr_array_header_t *reqs_arr = ap_requires(r);
    require_line *reqs;

    /* BUG FIX: tadc, 11-Nov-1995.  If there is no "requires" directive, 
     * then any user will do.
     */
    if (!reqs_arr) {
        return OK;
    }
    reqs = (require_line *)reqs_arr->elts;

    if (conf->auth_grpfile) {
        grpstatus = groups_for_user(r->pool, user, conf->auth_grpfile);
    }
    else {
        grpstatus = NULL;
    }

    for (x = 0; x < reqs_arr->nelts; x++) {

        if (!(reqs[x].method_mask & (AP_METHOD_BIT << m))) {
            continue;
        }

        method_restricted = 1;

        t = reqs[x].requirement;
        w = ap_getword_white(r->pool, &t);
        if (!strcmp(w, "valid-user")) {
            return OK;
        }
        if (!strcmp(w, "user")) {
            while (t[0]) {
                w = ap_getword_conf(r->pool, &t);
                if (!strcmp(user, w)) {
                    return OK;
                }
            }
        }
        else if (!strcmp(w, "group")) {
            if (!grpstatus) {
                return DECLINED;        /* DBM group?  Something else? */
            }

            while (t[0]) {
                w = ap_getword_conf(r->pool, &t);
                if (apr_table_get(grpstatus, w)) {
                    return OK;
                }
            }
        }
        else if (conf->auth_authoritative) {
            /* if we aren't authoritative, any require directive could be
             * valid even if we don't grok it.  However, if we are 
             * authoritative, we can warn the user they did something wrong.
             * That something could be a missing "AuthAuthoritative off", but
             * more likely is a typo in the require directive.
             */
            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                          "access to %s failed, reason: unknown require "
                          "directive:\"%s\"", r->uri, reqs[x].requirement);
        }
    }

    if (!method_restricted) {
        return OK;
    }

    if (!(conf->auth_authoritative)) {
        return DECLINED;
    }

    ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                  "access to %s failed, reason: user %s not allowed access",
                  r->uri, user);
        
    ap_note_basic_auth_failure(r);
    return HTTP_UNAUTHORIZED;
}

static void register_hooks(apr_pool_t *p)
{
    ap_hook_check_user_id(authenticate_basic_user,NULL,NULL,APR_HOOK_MIDDLE);
    ap_hook_auth_checker(check_user_access,NULL,NULL,APR_HOOK_MIDDLE);
}

module AP_MODULE_DECLARE_DATA auth_module =
{
    STANDARD20_MODULE_STUFF,
    create_auth_dir_config,     /* dir config creater */
    NULL,                       /* dir merger --- default is to override */
    NULL,                       /* server config */
    NULL,                       /* merge server config */
    auth_cmds,                  /* command apr_table_t */
    register_hooks              /* register hooks */
};