source/cgi.c

   1 /*
   2    some simple CGI helper routines
   3    Copyright (C) Andrew Tridgell 1997-1998
   4
   5    This program is free software; you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 2 of the License, or
   8    (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program; if not, write to the Free Software
  17    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  18 */
  19
  20
  21 #include <stdio.h>
  22 #include <stdlib.h>
  23 #include <sys/stat.h>
  24 #include <string.h>
  25 #include <fcntl.h>
  26 #include <unistd.h>
  27 #include <pwd.h>
  28
  29 #define MAX_VARIABLES 10000
  30
  31 #ifdef DEBUG_COMMENTS
  32 extern void print_title(char *fmt, ...);
  33 #endif
  34
  35 struct var {
  36         char *name;
  37         char *value;
  38 };
  39
  40 static struct var variables[MAX_VARIABLES];
  41 static int num_variables;
  42 static int content_length;
  43 static int request_post;
  44 static int request_get;
  45 static char *query_string;
  46
  47 static void unescape(char *buf)
  48 {
  49         char *p=buf;
  50
  51         while ((p=strchr(p,'+')))
  52                 *p = ' ';
  53
  54         p = buf;
  55
  56         while (p && *p && (p=strchr(p,'%'))) {
  57                 int c1 = p[1];
  58                 int c2 = p[2];
  59
  60                 if (c1 >= '0' && c1 <= '9')
  61                         c1 = c1 - '0';
  62                 else if (c1 >= 'A' && c1 <= 'F')
  63                         c1 = 10 + c1 - 'A';
  64                 else if (c1 >= 'a' && c1 <= 'f')
  65                         c1 = 10 + c1 - 'a';
  66                 else {p++; continue;}
  67
  68                 if (c2 >= '0' && c2 <= '9')
  69                         c2 = c2 - '0';
  70                 else if (c2 >= 'A' && c2 <= 'F')
  71                         c2 = 10 + c2 - 'A';
  72                 else if (c2 >= 'a' && c2 <= 'f')
  73                         c2 = 10 + c2 - 'a';
  74                 else {p++; continue;}
  75
  76                 *p = (c1<<4) | c2;
  77
  78                 memcpy(p+1, p+3, strlen(p+3)+1);
  79                 p++;
  80         }
  81 }
  82
  83
  84 static char *grab_line(FILE *f, int *cl)
  85 {
  86         char *ret;
  87         int i = 0;
  88         int len = 1024;
  89
  90         ret = (char *)malloc(len);
  91         if (!ret) return NULL;
  92
  93
  94         while ((*cl)) {
  95                 int c = fgetc(f);
  96                 (*cl)--;
  97
  98                 if (c == EOF) {
  99                         (*cl) = 0;
 100                         break;
 101                 }
 102
 103                 if (c == '\r') continue;
 104
 105                 if (strchr("\n&", c)) break;
 106
 107                 ret[i++] = c;
 108
 109                 if (i == len-1) {
 110                         char *ret2;
 111                         ret2 = (char *)realloc(ret, len*2);
 112                         if (!ret2) return ret;
 113                         len *= 2;
 114                         ret = ret2;
 115                 }
 116         }
 117
 118
 119         ret[i] = 0;
 120         return ret;
 121 }
 122
 123 /***************************************************************************
 124   load all the variables passed to the CGI program. May have multiple variables
 125   with the same name and the same or different values. Takes a file parameter
 126   for simulating CGI invocation eg loading saved preferences.
 127   ***************************************************************************/
 128 void cgi_load_variables(FILE *f1)
 129 {
 130         FILE *f = f1;
 131         static char *line;
 132         char *p, *s, *tok;
 133         int len;
 134
 135 #ifdef DEBUG_COMMENTS
 136         char dummy[100]="";
 137         print_title(dummy);
 138         printf("<!== Start dump in cgi_load_variables() %s ==>\n",__FILE__);
 139 #endif
 140
 141         if (!f1) {
 142                 f = stdin;
 143                 if (!content_length) {
 144                         p = getenv("CONTENT_LENGTH");
 145                         len = p?atoi(p):0;
 146                 } else {
 147                         len = content_length;
 148                 }
 149         } else {
 150                 fseek(f, 0, SEEK_END);
 151                 len = ftell(f);
 152                 fseek(f, 0, SEEK_SET);
 153         }
 154
 155
 156         if (len > 0 &&
 157             (f1 || request_post ||
 158              ((s=getenv("REQUEST_METHOD")) &&
 159               strcasecmp(s,"POST")==0))) {
 160                 while (len && (line=grab_line(f, &len))) {
 161                         p = strchr(line,'=');
 162                         if (!p) continue;
 163
 164                         *p = 0;
 165
 166                         variables[num_variables].name = strdup(line);
 167                         variables[num_variables].value = strdup(p+1);
 168
 169                         free(line);
 170
 171                         if (!variables[num_variables].name ||
 172                             !variables[num_variables].value)
 173                                 continue;
 174
 175                         unescape(variables[num_variables].value);
 176                         unescape(variables[num_variables].name);
 177
 178 #ifdef DEBUG_COMMENTS
 179                         printf("<!== POST var %s has value \"%s\"  ==>\n",
 180                                variables[num_variables].name,
 181                                variables[num_variables].value);
 182 #endif
 183
 184                         num_variables++;
 185                         if (num_variables == MAX_VARIABLES) break;
 186                 }
 187         }
 188
 189         if (f1) {
 190 #ifdef DEBUG_COMMENTS
 191                 printf("<!== End dump in cgi_load_variables() ==>\n");
 192 #endif
 193                 return;
 194         }
 195
 196         fclose(stdin);
 197
 198         if ((s=query_string) || (s=getenv("QUERY_STRING"))) {
 199                 for (tok=strtok(s,"&;");tok;tok=strtok(NULL,"&;")) {
 200                         p = strchr(tok,'=');
 201                         if (!p) continue;
 202
 203                         *p = 0;
 204
 205                         variables[num_variables].name = strdup(tok);
 206                         variables[num_variables].value = strdup(p+1);
 207
 208                         if (!variables[num_variables].name ||
 209                             !variables[num_variables].value)
 210                                 continue;
 211
 212                         unescape(variables[num_variables].value);
 213                         unescape(variables[num_variables].name);
 214
 215 #ifdef DEBUG_COMMENTS
 216                         printf("<!== Commandline var %s has value \"%s\"  ==>\n",
 217                                variables[num_variables].name,
 218                                variables[num_variables].value);
 219 #endif
 220                         num_variables++;
 221                         if (num_variables == MAX_VARIABLES) break;
 222                 }
 223
 224         }
 225 #ifdef DEBUG_COMMENTS
 226         printf("<!== End dump in cgi_load_variables() ==>\n");
 227 #endif
 228 }
 229
 230
 231 /***************************************************************************
 232   find a variable passed via CGI
 233   Doesn't quite do what you think in the case of POST text variables, because
 234   if they exist they might have a value of "" or even " ", depending on the
 235   browser. Also doesn't allow for variables[] containing multiple variables
 236   with the same name and the same or different values.
 237   ***************************************************************************/
 238 char *cgi_variable(char *name)
 239 {
 240         int i;
 241
 242         for (i=0;i<num_variables;i++)
 243                 if (strcmp(variables[i].name, name) == 0)
 244                         return variables[i].value;
 245         return NULL;
 246 }
 247
 248 /***************************************************************************
 249 return a particular cgi variable
 250   ***************************************************************************/
 251 char *cgi_vnum(int i, char **name)
 252 {
 253         if (i < 0 || i >= num_variables) return NULL;
 254         *name = variables[i].name;
 255         return variables[i].value;
 256 }
 257
 258 /***************************************************************************
 259   return the value of a CGI boolean variable.
 260   ***************************************************************************/
 261 int cgi_boolean(char *name, int def)
 262 {
 263         char *p = cgi_variable(name);
 264
 265         if (!p) return def;
 266
 267         return strcmp(p, "1") == 0;
 268 }
 269
 270 /***************************************************************************
 271 like strdup() but quotes < > and &
 272   ***************************************************************************/
 273 char *quotedup(char *s)
 274 {
 275         int i, n=0;
 276         int len;
 277         char *ret;
 278         char *d;
 279
 280         if (!s) return strdup("");
 281
 282         len = strlen(s);
 283
 284         for (i=0;i<len;i++)
 285                 if (s[i] == '<' || s[i] == '>' || s[i] == '&')
 286                         n++;
 287
 288         ret = malloc(len + n*6 + 1);
 289
 290         if (!ret) return NULL;
 291
 292         d = ret;
 293
 294         for (i=0;i<len;i++) {
 295                 switch (s[i]) {
 296                 case '<':
 297                         strcpy(d, "&lt;");
 298                         d += 4;
 299                         break;
 300
 301                 case '>':
 302                         strcpy(d, "&gt;");
 303                         d += 4;
 304                         break;
 305
 306                 case '&':
 307                         strcpy(d, "&amp;");
 308                         d += 5;
 309                         break;
 310
 311                 default:
 312                         *d++ = s[i];
 313                 }
 314         }
 315
 316         *d = 0;
 317
 318         return ret;
 319 }
 320
 321
 322 /***************************************************************************
 323 like strdup() but quotes a wide range of characters
 324   ***************************************************************************/
 325 char *urlquote(char *s)
 326 {
 327         int i, n=0;
 328         int len;
 329         char *ret;
 330         char *d;
 331         char *qlist = "\"\n\r'&<> \t+;";
 332
 333         if (!s) return strdup("");
 334
 335         len = strlen(s);
 336
 337         for (i=0;i<len;i++)
 338                 if (strchr(qlist, s[i])) n++;
 339
 340         ret = malloc(len + n*2 + 1);
 341
 342         if (!ret) return NULL;
 343
 344         d = ret;
 345
 346         for (i=0;i<len;i++) {
 347                 if (strchr(qlist,s[i])) {
 348                         sprintf(d, "%%%02X", (int)s[i]);
 349                         d += 3;
 350                 } else {
 351                         *d++ = s[i];
 352                 }
 353         }
 354
 355         *d = 0;
 356
 357         return ret;
 358 }
 359
 360
 361 /***************************************************************************
 362 like strdup() but quotes " characters
 363   ***************************************************************************/
 364 char *quotequotes(char *s)
 365 {
 366         int i, n=0;
 367         int len;
 368         char *ret;
 369         char *d;
 370
 371         if (!s) return strdup("");
 372
 373         len = strlen(s);
 374
 375         for (i=0;i<len;i++)
 376                 if (s[i] == '"')
 377                         n++;
 378
 379         ret = malloc(len + n*6 + 1);
 380
 381         if (!ret) return NULL;
 382
 383         d = ret;
 384
 385         for (i=0;i<len;i++) {
 386                 switch (s[i]) {
 387                 case '"':
 388                         strcpy(d, "&quot;");
 389                         d += 6;
 390                         break;
 391
 392                 default:
 393                         *d++ = s[i];
 394                 }
 395         }
 396
 397         *d = 0;
 398
 399         return ret;
 400 }
 401
 402
 403 /***************************************************************************
 404 quote spaces in a buffer
 405   ***************************************************************************/
 406 void quote_spaces(char *buf)
 407 {
 408         while (*buf) {
 409                 if (*buf == ' ') *buf = '+';
 410                 buf++;
 411         }
 412 }
 413
 414
 415
 416 /***************************************************************************
 417 tell a browser about a fatal error in the http processing
 418   ***************************************************************************/
 419 static void cgi_setup_error(char *err, char *header, char *info)
 420 {
 421         printf("HTTP/1.1 %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", err, header, err, err, info);
 422         exit(0);
 423 }
 424
 425
 426 /***************************************************************************
 427 decode a base64 string in-place - simple and slow algorithm
 428   ***************************************************************************/
 429 static void base64_decode(char *s)
 430 {
 431         char *b64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
 432         int bit_offset, byte_offset, idx, i;
 433         unsigned char *d = (unsigned char *)s;
 434         char *p;
 435
 436         i=0;
 437
 438         while (*s && (p=strchr(b64,*s))) {
 439                 idx = (int)(p - b64);
 440                 byte_offset = (i*6)/8;
 441                 bit_offset = (i*6)%8;
 442                 d[byte_offset] &= ~((1<<(8-bit_offset))-1);
 443                 if (bit_offset < 3) {
 444                         d[byte_offset] |= (idx << (2-bit_offset));
 445                 } else {
 446                         d[byte_offset] |= (idx >> (bit_offset-2));
 447                         d[byte_offset+1] = 0;
 448                         d[byte_offset+1] |= (idx << (8-(bit_offset-2))) & 0xFF;
 449                 }
 450                 s++; i++;
 451         }
 452 }
 453
 454
 455 /***************************************************************************
 456 handle a http authentication line
 457   ***************************************************************************/
 458 static int cgi_handle_authorization(char *line)
 459 {
 460         char *p, *user, *pass;
 461         struct passwd *pwd;
 462         int ret=0;
 463
 464         if (strncasecmp(line,"Basic ", 6)) {
 465                 cgi_setup_error("401 Bad Authorization", "",
 466                                 "Only basic authorization is understood");
 467         }
 468         line += 6;
 469         while (line[0] == ' ') line++;
 470         base64_decode(line);
 471         if (!(p=strchr(line,':'))) {
 472                 cgi_setup_error("401 Bad Authorization", "",
 473                                 "username/password must be supplied");
 474         }
 475         *p = 0;
 476         user = line;
 477         pass = p+1;
 478
 479         /* currently only allow connections as root */
 480         if (strcasecmp(user,"root")) {
 481                 cgi_setup_error("401 Bad Authorization", "",
 482                                 "incorrect username/password");
 483         }
 484
 485         pwd = getpwnam(user);
 486
 487         if (!strcmp((char *)crypt(pass, pwd->pw_passwd),pwd->pw_passwd)) {
 488                 ret = 1;
 489         }
 490
 491         memset(pass, 0, strlen(pass));
 492
 493         return ret;
 494 }
 495
 496
 497 /***************************************************************************
 498 handle a file download
 499   ***************************************************************************/
 500 static void cgi_download(char *file)
 501 {
 502         struct stat st;
 503         char buf[1024];
 504         int fd, l, i;
 505         char *p;
 506
 507         /* sanitise the filename */
 508         for (i=0;file[i];i++) {
 509                 if (!isalnum(file[i]) && !strchr("/.-_", file[i])) {
 510                         cgi_setup_error("404 File Not Found","",
 511                                         "Illegal character in filename");
 512                 }
 513         }
 514
 515         if (strstr(file,"..")) {
 516                 cgi_setup_error("404 File Not Found","",
 517                                 "Relative paths not allowed");
 518         }
 519
 520         if (!file_exist(file, &st)) {
 521                 cgi_setup_error("404 File Not Found","",
 522                                 "The requested file was not found");
 523         }
 524         fd = open(file,O_RDONLY);
 525         if (fd == -1) {
 526                 cgi_setup_error("404 File Not Found","",
 527                                 "The requested file was not found");
 528         }
 529         printf("HTTP/1.1 200 OK\r\n");
 530         if ((p=strrchr(file,'.'))) {
 531                 if (strcmp(p,".gif")==0 || strcmp(p,".jpg")==0) {
 532                         printf("Content-Type: image/gif\r\n");
 533                 } else {
 534                         printf("Content-Type: text/html\r\n");
 535                 }
 536         }
 537         printf("Content-Length: %d\r\n\r\n", (int)st.st_size);
 538         while ((l=read(fd,buf,sizeof(buf)))>0) {
 539                 fwrite(buf, 1, l, stdout);
 540         }
 541         close(fd);
 542         exit(0);
 543 }
 544
 545
 546 /***************************************************************************
 547 setup the cgi framework, handling the possability that this program is either
 548 run as a true cgi program by a web browser or is itself a mini web server
 549   ***************************************************************************/
 550 void cgi_setup(char *rootdir)
 551 {
 552         int authenticated = 0;
 553         char line[1024];
 554         char *url=NULL;
 555         char *p;
 556
 557         if (chdir(rootdir)) {
 558                 cgi_setup_error("400 Server Error", "",
 559                                 "chdir failed - the server is not configured correctly");
 560         }
 561
 562         if (getenv("CONTENT_LENGTH") || getenv("REQUEST_METHOD")) {
 563                 /* assume we are running under a real web server */
 564                 return;
 565         }
 566
 567         /* we are a mini-web server. We need to read the request from stdin
 568            and handle authentication etc */
 569         while (fgets(line, sizeof(line)-1, stdin)) {
 570                 if (line[0] == '\r' || line[0] == '\n') break;
 571                 if (strncasecmp(line,"GET ", 4)==0) {
 572                         request_get = 1;
 573                         url = strdup(&line[4]);
 574                 } else if (strncasecmp(line,"POST ", 5)==0) {
 575                         request_post = 1;
 576                         url = strdup(&line[5]);
 577                 } else if (strncasecmp(line,"PUT ", 4)==0) {
 578                         cgi_setup_error("400 Bad Request", "",
 579                                         "This server does not accept PUT requests");
 580                 } else if (strncasecmp(line,"Authorization: ", 15)==0) {
 581                         authenticated = cgi_handle_authorization(&line[15]);
 582                 } else if (strncasecmp(line,"Content-Length: ", 16)==0) {
 583                         content_length = atoi(&line[16]);
 584                 }
 585                 /* ignore all other requests! */
 586         }
 587
 588         if (!authenticated) {
 589                 cgi_setup_error("401 Authorization Required",
 590                                 "WWW-Authenticate: Basic realm=\"root\"\r\n",
 591                                 "You must be authenticated to use this service");
 592         }
 593
 594         if (!url) {
 595                 cgi_setup_error("400 Bad Request", "",
 596                                 "You must specify a GET or POST request");
 597         }
 598
 599         /* trim the URL */
 600         if ((p = strchr(url,' ')) || (p=strchr(url,'\t'))) {
 601                 *p = 0;
 602         }
 603         while (*url && strchr("\r\n",url[strlen(url)-1])) {
 604                 url[strlen(url)-1] = 0;
 605         }
 606
 607         /* anything following a ? in the URL is part of the query string */
 608         if ((p=strchr(url,'?'))) {
 609                 query_string = p+1;
 610                 *p = 0;
 611         }
 612
 613         if (strcmp(url,"/")) {
 614                 cgi_download(url+1);
 615         }
 616
 617         printf("HTTP/1.1 200 OK\r\nConnection: close\r\n");
 618
 619 }
 620
 621