/* 
**  mod_absec.c -- Apache sample absec module
**  [Autogenerated via ``apxs -n absec -g'']
**
**  To play with this sample module first compile it into a
**  DSO file and install it into Apache's modules directory 
**  by running:
**
**    $ apxs -c -i mod_absec.c
**
**  Then activate it in Apache's httpd.conf file for instance
**  for the URL /absec in as follows:
**
**    #   httpd.conf
**    LoadModule absec_module modules/mod_absec.so
**    <Location /absec>
**    SetHandler absec
**    </Location>
**
**  Then after restarting Apache via
**
**    $ apachectl restart
**
**  you immediately can request the URL /absec and watch for the
**  output of this module. This can be achieved for instance via:
**
**    $ lynx -mime_header http://localhost/absec 
**
**  The output should be similar to the following one:
**
**    HTTP/1.1 200 OK
**    Date: Tue, 31 Mar 1998 14:42:22 GMT
**    Server: Apache/1.3.4 (Unix)
**    Connection: close
**    Content-Type: text/html
**  
**    The sample page from mod_absec.c
*/ 

/*
    TEST URL
    http://10.211.55.15/absec?joe=blow
    
    INFORMATION SOURCES 

    https://apr.apache.org/docs/apr/1.5/group__apr__strings.html
    https://apr.apache.org/docs/apr-util/1.6/files.html

    https://httpd.apache.org/docs/2.4/developer/modguide.html
    http://www.ziviani.net/2011/how-to-create-an-apache-module

    https://en.wikipedia.org/wiki/Basic_access_authentication

*/

#include "httpd.h"
#include "http_config.h"
#include "http_core.h"
#include "http_protocol.h"
#include "ap_config.h"
#include "apr_base64.h"
#include "apr_strings.h"
#include "apr_portable.h"
#include "apr_user.h"

#include <pwd.h>
#include <sys/types.h>
#include <unistd.h>
#include "apr_want.h"

#include <shadow.h>
#include <sys/stat.h>

////////////////////////////////////////////////////////////////
/* Check user autentication against unix user/pass */
static int check_autentication(request_rec *r)
{
    return 0;
}

////////////////////////////////////////////////////////////////
/* Check check file perms */
static int check_autorization(request_rec *r)
{
    return 0;
}


////////////////////////////////////////////////////////////////
/* Main routine */
static int absec_handler(request_rec *r)
{
    // Is this module really called?
    if (strcmp(r->handler, "absec")) {
        return DECLINED;
    }


////////
/* check file permission on filesystem */
/* should include <sys/stat.h> */
    struct stat fperm;
    int status;
    status = stat(r->filename, &fperm);
    ap_rprintf(r, "File perms %o, owner %d, group %d (status %d)<br/>\r\n", fperm.st_mode, fperm.st_uid, fperm.st_gid, status);

    // If file is world readable return content
    if (fperm.st_mode & 0x4) {
        ap_rprintf(r, "Fichier public<br/>\r\n");
        return (DECLINED);
    }

    const char* auth64p;
    if (!r->header_only)
        // Check if we have an auth header
        auth64p = apr_table_get(r->headers_in,"Authorization");

    // If no basic auth, ask for one
    if (auth64p==NULL) {
        r->content_type = "text/html";      
        apr_table_setn(r->err_headers_out,
                (PROXYREQ_PROXY == r->proxyreq) ? "Proxy-Authenticate"
                                                : "WWW-Authenticate",
                apr_pstrcat(r->pool, "Basic realm=\"", ap_auth_name(r),
                            "\"", NULL));
        return HTTP_UNAUTHORIZED;
    }

////////
/* Retrieve user/pass from http basic auth header */
    // Get the basic auth base64 string and decode it
    // Start at char 6 to skip 'Basic '
    char *auth64;
    auth64 = apr_pstrdup(r->pool, auth64p+6);
    char *auth;
    auth = apr_pcalloc(r->pool, 64);
    apr_base64_decode(auth, auth64);

    // Validate user/pass against unix cred
    char *user;
    char *pass;
    user = apr_strtok(auth, ":", &pass);

    r->content_type = "text/html";      
    //ap_rprintf(r, "The sample page from mod_absec.c %s \n<br/>", r->args);
    ap_rprintf(r, "Url: %s from %s \n<br/>", r->filename, r->uri);
    //ap_rprintf(r, "Headers Authorization: %s \n<br/>", auth64);
    //ap_rprintf(r, "User/Pass: %s/%s \n<br/>", user, pass);

////////
// Get UID, GIDs for the user
/* Working example, but just UID not PW */
    apr_status_t ret;
    apr_uid_t i;
    apr_gid_t g;
    ret = apr_uid_get	(	&i, &g, user, r->pool );
    ap_rprintf(r, "Result2: G:%d, I:%d \n<br/>", g,i);

////////
/* Retrieve PW from /etc/passwd */
/* Should include <pwd.h> */
    struct passwd *pw; 
    if((pw = getpwnam(user)) == NULL) 
    { 
        ap_rprintf(r, "NULL \n<br/>");
        apr_table_setn(r->err_headers_out,
            (PROXYREQ_PROXY == r->proxyreq) ? "Proxy-Authenticate"
                                            : "WWW-Authenticate",
            apr_pstrcat(r->pool, "Basic realm=\"", ap_auth_name(r),
            "\"", NULL));
        return HTTP_UNAUTHORIZED;
    } 
    else 
    { 
        ap_rprintf(r, "Unix PW : %s \n<br/>", pw->pw_passwd);
    } 

////////
/* Retrieve PW from /etc/shadow */
/* Should include <shadow.h> */
    struct spwd *spw; 
    errno = 0;
    if((spw = getspnam(user)) == NULL) 
    { 
            ap_rprintf(r, "NULL %d\n<br/>", errno);
        apr_table_setn(r->err_headers_out,
                (PROXYREQ_PROXY == r->proxyreq) ? "Proxy-Authenticate"
                                                : "WWW-Authenticate",
                apr_pstrcat(r->pool, "Basic realm=\"", ap_auth_name(r),
                            "\"", NULL));
        return HTTP_UNAUTHORIZED;
    } 
    else 
    { 
            ap_rprintf(r, "Shadow PW : %s \n<br/>", spw->sp_pwdp);
    } 

    if (spw->sp_pwdp[0] == 'x' || spw->sp_pwdp[0] == '*' || spw->sp_pwdp[0] == '!') {
        apr_table_setn(r->err_headers_out,
                (PROXYREQ_PROXY == r->proxyreq) ? "Proxy-Authenticate"
                                                : "WWW-Authenticate",
                apr_pstrcat(r->pool, "Basic realm=\"", ap_auth_name(r),
                            "\"", NULL));
        return HTTP_UNAUTHORIZED;
    }

////////
/* Encrypt and compare shadow password */

// TODO : Valider qu'on a un user
// TODO : Valider qu'il y a un password (pas * ! rien)
    char *encrypted;
    const char *correct;
    int rrr;
    encrypted = crypt(pass, spw->sp_pwdp);
    rrr = strcmp(encrypted, spw->sp_pwdp);
    ap_rprintf(r, "compare pw : %s \n<br/>", encrypted);;
    ap_rprintf(r, "compare : %d \n<br/>", rrr);
    if (rrr!=0) {
        apr_table_setn(r->err_headers_out,
                (PROXYREQ_PROXY == r->proxyreq) ? "Proxy-Authenticate"
                                                : "WWW-Authenticate",
                apr_pstrcat(r->pool, "Basic realm=\"", ap_auth_name(r),
                            "\"", NULL));
        return HTTP_UNAUTHORIZED;
    }


    // If file is user readable and user match return content
    if ((fperm.st_uid==i) && (fperm.st_mode & 0400)) {
        ap_rprintf(r, "Fichier propriétaire<br/>\r\n");
        return (DECLINED);
    }

    // If file is group readable and primary group match return content
    if ((fperm.st_gid==g) && (fperm.st_mode & 0040)) {
        ap_rprintf(r, "Fichier groupe<br/>\r\n");
        return (DECLINED);
    }

    // now check supplemental groups
    //ap_rprintf(r, "Fichier propriétaire %d %d %o %o<br/>\r\n", fperm.st_uid, i, fperm.st_mode, 0400);

    // else decline
    ap_rprintf(r, "Aucuns droits de voir le fichier<br/>\r\n");
        apr_table_setn(r->err_headers_out,
                (PROXYREQ_PROXY == r->proxyreq) ? "Proxy-Authenticate"
                                                : "WWW-Authenticate",
                apr_pstrcat(r->pool, "Basic realm=\"", ap_auth_name(r),
                            "\"", NULL));
    return HTTP_UNAUTHORIZED;
    return OK;

}

////////////////////////////////////////////////////////////////
static void absec_register_hooks(apr_pool_t *p)
{
    //ap_hook_handler(absec_handler, NULL, NULL, APR_HOOK_MIDDLE);
    ap_hook_handler(absec_handler, NULL, NULL, APR_HOOK_LAST);
}

////////////////////////////////////////////////////////////////
/* Dispatch list for API hooks */
module AP_MODULE_DECLARE_DATA absec_module = {
    STANDARD20_MODULE_STUFF, 
    NULL,                  /* create per-dir    config structures */
    NULL,                  /* merge  per-dir    config structures */
    NULL,                  /* create per-server config structures */
    NULL,                  /* merge  per-server config structures */
    NULL,                  /* table of config file commands       */
    absec_register_hooks  /* register hooks                      */
};