source: branches/samba-3.5.x/source3/web/cgi.c

/* 
   some simple CGI helper routines
   Copyright (C) Andrew Tridgell 1997-1998
   
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.
   
   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.  See the
   GNU General Public License for more details.
   
   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/


#include "includes.h"
#include "web/swat_proto.h"
#include "secrets.h"
#include "../lib/util/util.h"

#define MAX_VARIABLES 10000

/* set the expiry on fixed pages */
#define EXPIRY_TIME (60*60*24*7)

#ifdef DEBUG_COMMENTS
extern void print_title(char *fmt, ...);
#endif

struct cgi_var {
        char *name;
        char *value;
};

static struct cgi_var variables[MAX_VARIABLES];
static int num_variables;
static int content_length;
static int request_post;
static char *query_string;
static const char *baseurl;
static char *pathinfo;
static char *C_user;
static char *C_pass;
static char *C_nonce;
static bool inetd_server;
static bool got_request;

static char *grab_line(FILE *f, int *cl)
{
        char *ret = NULL;
        int i = 0;
        int len = 0;

        while ((*cl)) {
                int c;
        
                if (i == len) {
                        char *ret2;
                        if (len == 0) len = 1024;
                        else len *= 2;
                        ret2 = (char *)SMB_REALLOC_KEEP_OLD_ON_ERROR(ret, len);
                        if (!ret2) return ret;
                        ret = ret2;
                }
        
                c = fgetc(f);
                (*cl)--;

                if (c == EOF) {
                        (*cl) = 0;
                        break;
                }
                
                if (c == '\r') continue;

                if (strchr_m("\n&", c)) break;

                ret[i++] = c;

        }
        
        if (ret) {
                ret[i] = 0;
        }
        return ret;
}

/**
 URL encoded strings can have a '+', which should be replaced with a space

 (This was in rfc1738_unescape(), but that broke the squid helper)
**/

static void plus_to_space_unescape(char *buf)
{
        char *p=buf;

        while ((p=strchr_m(p,'+')))
                *p = ' ';
}

/***************************************************************************
  load all the variables passed to the CGI program. May have multiple variables
  with the same name and the same or different values. Takes a file parameter
  for simulating CGI invocation eg loading saved preferences.
  ***************************************************************************/
void cgi_load_variables(void)
{
        static char *line;
        char *p, *s, *tok;
        int len, i;
        FILE *f = stdin;

#ifdef DEBUG_COMMENTS
        char dummy[100]="";
        print_title(dummy);
        d_printf("<!== Start dump in cgi_load_variables() %s ==>\n",__FILE__);
#endif

        if (!content_length) {
                p = getenv("CONTENT_LENGTH");
                len = p?atoi(p):0;
        } else {
                len = content_length;
        }


        if (len > 0 && 
            (request_post ||
             ((s=getenv("REQUEST_METHOD")) && 
              strequal(s,"POST")))) {
                while (len && (line=grab_line(f, &len))) {
                        p = strchr_m(line,'=');
                        if (!p) continue;
                        
                        *p = 0;
                        
                        variables[num_variables].name = SMB_STRDUP(line);
                        variables[num_variables].value = SMB_STRDUP(p+1);

                        SAFE_FREE(line);
                        
                        if (!variables[num_variables].name || 
                            !variables[num_variables].value)
                                continue;

                        plus_to_space_unescape(variables[num_variables].value);
                        rfc1738_unescape(variables[num_variables].value);
                        plus_to_space_unescape(variables[num_variables].name);
                        rfc1738_unescape(variables[num_variables].name);

#ifdef DEBUG_COMMENTS
                        printf("<!== POST var %s has value \"%s\"  ==>\n",
                               variables[num_variables].name,
                               variables[num_variables].value);
#endif
                        
                        num_variables++;
                        if (num_variables == MAX_VARIABLES) break;
                }
        }

        fclose(stdin);
        open("/dev/null", O_RDWR);

        if ((s=query_string) || (s=getenv("QUERY_STRING"))) {
                char *saveptr;
                for (tok=strtok_r(s, "&;", &saveptr); tok;
                     tok=strtok_r(NULL, "&;", &saveptr)) {
                        p = strchr_m(tok,'=');
                        if (!p) continue;
                        
                        *p = 0;
                        
                        variables[num_variables].name = SMB_STRDUP(tok);
                        variables[num_variables].value = SMB_STRDUP(p+1);

                        if (!variables[num_variables].name ||
                            !variables[num_variables].value)
                                continue;

                        plus_to_space_unescape(variables[num_variables].value);
                        rfc1738_unescape(variables[num_variables].value);
                        plus_to_space_unescape(variables[num_variables].name);
                        rfc1738_unescape(variables[num_variables].name);

#ifdef DEBUG_COMMENTS
                        printf("<!== Commandline var %s has value \"%s\"  ==>\n",
                               variables[num_variables].name,
                               variables[num_variables].value);
#endif
                        num_variables++;
                        if (num_variables == MAX_VARIABLES) break;
                }

        }
#ifdef DEBUG_COMMENTS
        printf("<!== End dump in cgi_load_variables() ==>\n");
#endif

        /* variables from the client are in UTF-8 - convert them
           to our internal unix charset before use */
        for (i=0;i<num_variables;i++) {
                TALLOC_CTX *frame = talloc_stackframe();
                char *dest = NULL;
                size_t dest_len;

                convert_string_talloc(frame, CH_UTF8, CH_UNIX,
                               variables[i].name, strlen(variables[i].name),
                               &dest, &dest_len, True);
                SAFE_FREE(variables[i].name);
                variables[i].name = SMB_STRDUP(dest ? dest : "");

                dest = NULL;
                convert_string_talloc(frame, CH_UTF8, CH_UNIX,
                               variables[i].value, strlen(variables[i].value),
                               &dest, &dest_len, True);
                SAFE_FREE(variables[i].value);
                variables[i].value = SMB_STRDUP(dest ? dest : "");
                TALLOC_FREE(frame);
        }
}


/***************************************************************************
  find a variable passed via CGI
  Doesn't quite do what you think in the case of POST text variables, because
  if they exist they might have a value of "" or even " ", depending on the
  browser. Also doesn't allow for variables[] containing multiple variables
  with the same name and the same or different values.
  ***************************************************************************/

const char *cgi_variable(const char *name)
{
        int i;

        for (i=0;i<num_variables;i++)
                if (strcmp(variables[i].name, name) == 0)
                        return variables[i].value;
        return NULL;
}

/***************************************************************************
 Version of the above that can't return a NULL pointer.
***************************************************************************/

const char *cgi_variable_nonull(const char *name)
{
        const char *var = cgi_variable(name);
        if (var) {
                return var;
        } else {
                return "";
        }
}

/***************************************************************************
tell a browser about a fatal error in the http processing
  ***************************************************************************/
static void cgi_setup_error(const char *err, const char *header, const char *info)
{
        if (!got_request) {
                /* damn browsers don't like getting cut off before they give a request */
                char line[1024];
                while (fgets(line, sizeof(line)-1, stdin)) {
                        if (strnequal(line,"GET ", 4) || 
                            strnequal(line,"POST ", 5) ||
                            strnequal(line,"PUT ", 4)) {
                                break;
                        }
                }
        }

        d_printf("HTTP/1.0 %s\r\n%sConnection: close\r\nContent-Type: text/html\r\n\r\n<HTML><HEAD><TITLE>%s</TITLE></HEAD><BODY><H1>%s</H1>%s<p></BODY></HTML>\r\n\r\n", err, header, err, err, info);
        fclose(stdin);
        fclose(stdout);
        exit(0);
}


/***************************************************************************
tell a browser about a fatal authentication error
  ***************************************************************************/
static void cgi_auth_error(void)
{
        if (inetd_server) {
                cgi_setup_error("401 Authorization Required", 
                                "WWW-Authenticate: Basic realm=\"SWAT\"\r\n",
                                "You must be authenticated to use this service");
        } else {
                printf("Content-Type: text/html\r\n");

                printf("\r\n<HTML><HEAD><TITLE>SWAT</TITLE></HEAD>\n");
                printf("<BODY><H1>Installation Error</H1>\n");
                printf("SWAT must be installed via inetd. It cannot be run as a CGI script<p>\n");
                printf("</BODY></HTML>\r\n");
        }
        exit(0);
}

/***************************************************************************
authenticate when we are running as a CGI
  ***************************************************************************/
static void cgi_web_auth(void)
{
        const char *user = getenv("REMOTE_USER");
        struct passwd *pwd;
        const char *head = "Content-Type: text/html\r\n\r\n<HTML><BODY><H1>SWAT installation Error</H1>\n";
        const char *tail = "</BODY></HTML>\r\n";

        if (!user) {
                printf("%sREMOTE_USER not set. Not authenticated by web server.<br>%s\n",
                       head, tail);
                exit(0);
        }

#ifndef __OS2__
        pwd = Get_Pwnam_alloc(talloc_autofree_context(), user);
        
        if (!pwd) {
                printf("%sCannot find user %s<br>%s\n", head, user, tail);
                exit(0);
        }

        C_user = SMB_STRDUP(user);

        if (!setuid(0)) {
                C_pass = SMB_STRDUP(cgi_nonce());
        }
        setuid(pwd->pw_uid);
        if (geteuid() != pwd->pw_uid || getuid() != pwd->pw_uid) {
                printf("%sFailed to become user %s - uid=%d/%d<br>%s\n", 
                       head, user, (int)geteuid(), (int)getuid(), tail);
                exit(0);
        }
        TALLOC_FREE(pwd);
#endif
}


/***************************************************************************
handle a http authentication line
  ***************************************************************************/
static bool cgi_handle_authorization(char *line)
{
        char *p;
        fstring user, user_pass;
        struct passwd *pass = NULL;

        if (!strnequal(line,"Basic ", 6)) {
                goto err;
        }
        line += 6;
        while (line[0] == ' ') line++;
        base64_decode_inplace(line);
        if (!(p=strchr_m(line,':'))) {
                /*
                 * Always give the same error so a cracker
                 * cannot tell why we fail.
                 */
                goto err;
        }
        *p = 0;

        convert_string(CH_UTF8, CH_UNIX, 
                       line, -1, 
                       user, sizeof(user), True);

        convert_string(CH_UTF8, CH_UNIX, 
                       p+1, -1, 
                       user_pass, sizeof(user_pass), True);

        /*
         * Try and get the user from the UNIX password file.
         */
        
        pass = Get_Pwnam_alloc(talloc_autofree_context(), user);
        
        /*
         * Validate the password they have given.
         */
        
        if NT_STATUS_IS_OK(pass_check(pass, user, user_pass, 
                      strlen(user_pass), NULL, False)) {
                
                if (pass) {
                        /*
                         * Password was ok.
                         */
                        
                        if ( initgroups(pass->pw_name, pass->pw_gid) != 0 )
                                goto err;

                        become_user_permanently(pass->pw_uid, pass->pw_gid);
                        
                        /* Save the users name */
                        C_user = SMB_STRDUP(user);
                        C_pass = SMB_STRDUP(user_pass);
                        TALLOC_FREE(pass);
                        return True;
                }
        }
        
err:
        cgi_setup_error("401 Bad Authorization", 
                        "WWW-Authenticate: Basic realm=\"SWAT\"\r\n",
                        "username or password incorrect");

        TALLOC_FREE(pass);
        return False;
}

/***************************************************************************
is this root?
  ***************************************************************************/
bool am_root(void)
{
        if (geteuid() == 0) {
                return( True);
        } else {
                return( False);
        }
}

/***************************************************************************
return a ptr to the users name
  ***************************************************************************/
char *cgi_user_name(void)
{
        return(C_user);
}

/***************************************************************************
return a ptr to the users password
  ***************************************************************************/
char *cgi_user_pass(void)
{
        return(C_pass);
}

/***************************************************************************
return a ptr to the nonce
  ***************************************************************************/
char *cgi_nonce(void)
{
        const char *head = "Content-Type: text/html\r\n\r\n<HTML><BODY><H1>SWAT installation Error</H1>\n";
        const char *tail = "</BODY></HTML>\r\n";
        C_nonce = secrets_fetch_generic("root", "SWAT");
        if (C_nonce == NULL) {
                char *tmp_pass = NULL;
                tmp_pass = generate_random_str(talloc_tos(), 16);
                if (tmp_pass == NULL) {
                        printf("%sFailed to create random nonce for "
                               "SWAT session\n<br>%s\n", head, tail);
                        exit(0);
                }
                secrets_store_generic("root", "SWAT", tmp_pass);
                C_nonce = SMB_STRDUP(tmp_pass);
                TALLOC_FREE(tmp_pass);
        }
        return(C_nonce);
}


/***************************************************************************
handle a file download
  ***************************************************************************/
static void cgi_download(char *file)
{
        SMB_STRUCT_STAT st;
        char buf[1024];
        int fd, l, i;
        char *p;
        char *lang;

        /* sanitise the filename */
        for (i=0;file[i];i++) {
                if (!isalnum((int)file[i]) && !strchr_m("/.-_", file[i])) {
                        cgi_setup_error("404 File Not Found","",
                                        "Illegal character in filename");
                }
        }

        if (sys_stat(file, &st, false) != 0)    {
                cgi_setup_error("404 File Not Found","",
                                "The requested file was not found");
        }

        if (S_ISDIR(st.st_ex_mode))
        {
                snprintf(buf, sizeof(buf), "%s/index.html", file);
                if (!file_exist_stat(buf, &st, false)
                    || !S_ISREG(st.st_ex_mode))
                {
                        cgi_setup_error("404 File Not Found","",
                                        "The requested file was not found");
                }
        }
        else if (S_ISREG(st.st_ex_mode))
        {
                snprintf(buf, sizeof(buf), "%s", file);
        }
        else
        {
                cgi_setup_error("404 File Not Found","",
                                "The requested file was not found");
        }

        fd = web_open(buf,O_RDONLY,0);
        if (fd == -1) {
                cgi_setup_error("404 File Not Found","",
                                "The requested file was not found");
        }
        printf("HTTP/1.0 200 OK\r\n");
        if ((p=strrchr_m(buf, '.'))) {
                if (strcmp(p,".gif")==0) {
                        printf("Content-Type: image/gif\r\n");
                } else if (strcmp(p,".jpg")==0) {
                        printf("Content-Type: image/jpeg\r\n");
                } else if (strcmp(p,".png")==0) {
                        printf("Content-Type: image/png\r\n");
                } else if (strcmp(p,".css")==0) {
                        printf("Content-Type: text/css\r\n");
                } else if (strcmp(p,".txt")==0) {
                        printf("Content-Type: text/plain\r\n");
                } else {
                        printf("Content-Type: text/html\r\n");
                }
        }
        printf("Expires: %s\r\n", 
                   http_timestring(talloc_tos(), time(NULL)+EXPIRY_TIME));

        lang = lang_tdb_current();
        if (lang) {
                printf("Content-Language: %s\r\n", lang);
        }

        printf("Content-Length: %d\r\n\r\n", (int)st.st_ex_size);
        while ((l=read(fd,buf,sizeof(buf)))>0) {
                if (fwrite(buf, 1, l, stdout) != l) {
                        break;
                }
        }
        close(fd);
        exit(0);
}




/**
 * @brief Setup the CGI framework.
 *
 * Setup the cgi framework, handling the possibility that this program
 * is either run as a true CGI program with a gateway to a web server, or
 * is itself a mini web server.
 **/
void cgi_setup(const char *rootdir, int auth_required)
{
        bool authenticated = False;
        char line[1024];
        char *url=NULL;
        char *p;
        char *lang;

        if (chdir(rootdir)) {
                cgi_setup_error("500 Server Error", "",
                                "chdir failed - the server is not configured correctly");
        }

        /* Handle the possibility we might be running as non-root */
        sec_init();

        if ((lang=getenv("HTTP_ACCEPT_LANGUAGE"))) {
                /* if running as a cgi program */
                web_set_lang(lang);
        }

        /* maybe we are running under a web server */
        if (getenv("CONTENT_LENGTH") || getenv("REQUEST_METHOD")) {
                if (auth_required) {
                        cgi_web_auth();
                }
                return;
        }

        inetd_server = True;

        if (!check_access(1, lp_hostsallow(-1), lp_hostsdeny(-1))) {
                cgi_setup_error("403 Forbidden", "",
                                "Samba is configured to deny access from this client\n<br>Check your \"hosts allow\" and \"hosts deny\" options in smb.conf ");
        }

        /* we are a mini-web server. We need to read the request from stdin
           and handle authentication etc */
        while (fgets(line, sizeof(line)-1, stdin)) {
                if (line[0] == '\r' || line[0] == '\n') break;
                if (strnequal(line,"GET ", 4)) {
                        got_request = True;
                        url = SMB_STRDUP(&line[4]);
                } else if (strnequal(line,"POST ", 5)) {
                        got_request = True;
                        request_post = 1;
                        url = SMB_STRDUP(&line[5]);
                } else if (strnequal(line,"PUT ", 4)) {
                        got_request = True;
                        cgi_setup_error("400 Bad Request", "",
                                        "This server does not accept PUT requests");
                } else if (strnequal(line,"Authorization: ", 15)) {
                        authenticated = cgi_handle_authorization(&line[15]);
                } else if (strnequal(line,"Content-Length: ", 16)) {
                        content_length = atoi(&line[16]);
                } else if (strnequal(line,"Accept-Language: ", 17)) {
                        web_set_lang(&line[17]);
                }
                /* ignore all other requests! */
        }

        if (auth_required && !authenticated) {
                cgi_auth_error();
        }

        if (!url) {
                cgi_setup_error("400 Bad Request", "",
                                "You must specify a GET or POST request");
        }

        /* trim the URL */
        if ((p = strchr_m(url,' ')) || (p=strchr_m(url,'\t'))) {
                *p = 0;
        }
        while (*url && strchr_m("\r\n",url[strlen(url)-1])) {
                url[strlen(url)-1] = 0;
        }

        /* anything following a ? in the URL is part of the query string */
        if ((p=strchr_m(url,'?'))) {
                query_string = p+1;
                *p = 0;
        }

        string_sub(url, "/swat/", "", 0);

        if (url[0] != '/' && strstr(url,"..")==0) {
                cgi_download(url);
        }

        printf("HTTP/1.0 200 OK\r\nConnection: close\r\n");
        printf("Date: %s\r\n", http_timestring(talloc_tos(), time(NULL)));
        baseurl = "";
        pathinfo = url+1;
}


/***************************************************************************
return the current pages URL
  ***************************************************************************/
const char *cgi_baseurl(void)
{
        if (inetd_server) {
                return baseurl;
        }
        return getenv("SCRIPT_NAME");
}

/***************************************************************************
return the current pages path info
  ***************************************************************************/
const char *cgi_pathinfo(void)
{
        char *r;
        if (inetd_server) {
                return pathinfo;
        }
        r = getenv("PATH_INFO");
        if (!r) return "";
        if (*r == '/') r++;
        return r;
}

/***************************************************************************
return the hostname of the client
  ***************************************************************************/
const char *cgi_remote_host(void)
{
        if (inetd_server) {
                return get_peer_name(1,False);
        }
        return getenv("REMOTE_HOST");
}

/***************************************************************************
return the hostname of the client
  ***************************************************************************/
const char *cgi_remote_addr(void)
{
        if (inetd_server) {
                char addr[INET6_ADDRSTRLEN];
                get_peer_addr(1,addr,sizeof(addr));
                return talloc_strdup(talloc_tos(), addr);
        }
        return getenv("REMOTE_ADDR");
}


/***************************************************************************
return True if the request was a POST
  ***************************************************************************/
bool cgi_waspost(void)
{
        if (inetd_server) {
                return request_post;
        }
        return strequal(getenv("REQUEST_METHOD"), "POST");
}