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 static char *baseurl;
  47
  48 static void unescape(char *buf)
  49 {
  50         char *p=buf;
  51
  52         while ((p=strchr(p,'+')))
  53                 *p = ' ';
  54
  55         p = buf;
  56
  57         while (p && *p && (p=strchr(p,'%'))) {
  58                 int c1 = p[1];
  59                 int c2 = p[2];
  60
  61                 if (c1 >= '0' && c1 <= '9')
  62                         c1 = c1 - '0';
  63                 else if (c1 >= 'A' && c1 <= 'F')
  64                         c1 = 10 + c1 - 'A';
  65                 else if (c1 >= 'a' && c1 <= 'f')
  66                         c1 = 10 + c1 - 'a';
  67                 else {p++; continue;}
  68
  69                 if (c2 >= '0' && c2 <= '9')
  70                         c2 = c2 - '0';
  71                 else if (c2 >= 'A' && c2 <= 'F')
  72                         c2 = 10 + c2 - 'A';
  73                 else if (c2 >= 'a' && c2 <= 'f')
  74                         c2 = 10 + c2 - 'a';
  75                 else {p++; continue;}
  76
  77                 *p = (c1<<4) | c2;
  78
  79                 memcpy(p+1, p+3, strlen(p+3)+1);
  80                 p++;
  81         }
  82 }
  83
  84
  85 static char *grab_line(FILE *f, int *cl)
  86 {
  87         char *ret;
  88         int i = 0;
  89         int len = 1024;
  90
  91         ret = (char *)malloc(len);
  92         if (!ret) return NULL;
  93
  94
  95         while ((*cl)) {
  96                 int c = fgetc(f);
  97                 (*cl)--;
  98
  99                 if (c == EOF) {
 100                         (*cl) = 0;
 101                         break;
 102                 }
 103
 104                 if (c == '\r') continue;
 105
 106                 if (strchr("\n&", c)) break;
 107
 108                 ret[i++] = c;
 109
 110                 if (i == len-1) {
 111                         char *ret2;
 112                         ret2 = (char *)realloc(ret, len*2);
 113                         if (!ret2) return ret;
 114                         len *= 2;
 115                         ret = ret2;
 116                 }
 117         }
 118
 119
 120         ret[i] = 0;
 121         return ret;
 122 }
 123
 124 /***************************************************************************
 125   load all the variables passed to the CGI program. May have multiple variables
 126   with the same name and the same or different values. Takes a file parameter
 127   for simulating CGI invocation eg loading saved preferences.
 128   ***************************************************************************/
 129 void cgi_load_variables(FILE *f1)
 130 {
 131         FILE *f = f1;
 132         static char *line;
 133         char *p, *s, *tok;
 134         int len;
 135
 136 #ifdef DEBUG_COMMENTS
 137         char dummy[100]="";
 138         print_title(dummy);
 139         printf("<!== Start dump in cgi_load_variables() %s ==>\n",__FILE__);
 140 #endif
 141
 142         if (!f1) {
 143                 f = stdin;
 144                 if (!content_length) {
 145                         p = getenv("CONTENT_LENGTH");
 146                         len = p?atoi(p):0;
 147                 } else {
 148                         len = content_length;
 149                 }
 150         } else {
 151                 fseek(f, 0, SEEK_END);
 152                 len = ftell(f);
 153                 fseek(f, 0, SEEK_SET);
 154         }
 155
 156
 157         if (len > 0 &&
 158             (f1 || request_post ||
 159              ((s=getenv("REQUEST_METHOD")) &&
 160               strcasecmp(s,"POST")==0))) {
 161                 while (len && (line=grab_line(f, &len))) {
 162                         p = strchr(line,'=');
 163                         if (!p) continue;
 164
 165                         *p = 0;
 166
 167                         variables[num_variables].name = strdup(line);
 168                         variables[num_variables].value = strdup(p+1);
 169
 170                         free(line);
 171
 172                         if (!variables[num_variables].name ||
 173                             !variables[num_variables].value)
 174                                 continue;
 175
 176                         unescape(variables[num_variables].value);
 177                         unescape(variables[num_variables].name);
 178
 179 #ifdef DEBUG_COMMENTS
 180                         printf("<!== POST var %s has value \"%s\"  ==>\n",
 181                                variables[num_variables].name,
 182                                variables[num_variables].value);
 183 #endif
 184
 185                         num_variables++;
 186                         if (num_variables == MAX_VARIABLES) break;
 187                 }
 188         }
 189
 190         if (f1) {
 191 #ifdef DEBUG_COMMENTS
 192                 printf("<!== End dump in cgi_load_variables() ==>\n");
 193 #endif
 194                 return;
 195         }
 196
 197         fclose(stdin);
 198
 199         if ((s=query_string) || (s=getenv("QUERY_STRING"))) {
 200                 for (tok=strtok(s,"&;");tok;tok=strtok(NULL,"&;")) {
 201                         p = strchr(tok,'=');
 202                         if (!p) continue;
 203
 204                         *p = 0;
 205
 206                         variables[num_variables].name = strdup(tok);
 207                         variables[num_variables].value = strdup(p+1);
 208
 209                         if (!variables[num_variables].name ||
 210                             !variables[num_variables].value)
 211                                 continue;
 212
 213                         unescape(variables[num_variables].value);
 214                         unescape(variables[num_variables].name);
 215
 216 #ifdef DEBUG_COMMENTS
 217                         printf("<!== Commandline var %s has value \"%s\"  ==>\n",
 218                                variables[num_variables].name,
 219                                variables[num_variables].value);
 220 #endif
 221                         num_variables++;
 222                         if (num_variables == MAX_VARIABLES) break;
 223                 }
 224
 225         }
 226 #ifdef DEBUG_COMMENTS
 227         printf("<!== End dump in cgi_load_variables() ==>\n");
 228 #endif
 229 }
 230
 231
 232 /***************************************************************************
 233   find a variable passed via CGI
 234   Doesn't quite do what you think in the case of POST text variables, because
 235   if they exist they might have a value of "" or even " ", depending on the
 236   browser. Also doesn't allow for variables[] containing multiple variables
 237   with the same name and the same or different values.
 238   ***************************************************************************/
 239 char *cgi_variable(char *name)
 240 {
 241         int i;
 242
 243         for (i=0;i<num_variables;i++)
 244                 if (strcmp(variables[i].name, name) == 0)
 245                         return variables[i].value;
 246         return NULL;
 247 }
 248
 249 /***************************************************************************
 250 return a particular cgi variable
 251   ***************************************************************************/
 252 char *cgi_vnum(int i, char **name)
 253 {
 254         if (i < 0 || i >= num_variables) return NULL;
 255         *name = variables[i].name;
 256         return variables[i].value;
 257 }
 258
 259 /***************************************************************************
 260   return the value of a CGI boolean variable.
 261   ***************************************************************************/
 262 int cgi_boolean(char *name, int def)
 263 {
 264         char *p = cgi_variable(name);
 265
 266         if (!p) return def;
 267
 268         return strcmp(p, "1") == 0;
 269 }
 270
 271 /***************************************************************************
 272 like strdup() but quotes < > and &
 273   ***************************************************************************/
 274 char *quotedup(char *s)
 275 {
 276         int i, n=0;
 277         int len;
 278         char *ret;
 279         char *d;
 280
 281         if (!s) return strdup("");
 282
 283         len = strlen(s);
 284
 285         for (i=0;i<len;i++)
 286                 if (s[i] == '<' || s[i] == '>' || s[i] == '&')
 287                         n++;
 288
 289         ret = malloc(len + n*6 + 1);
 290
 291         if (!ret) return NULL;
 292
 293         d = ret;
 294
 295         for (i=0;i<len;i++) {
 296                 switch (s[i]) {
 297                 case '<':
 298                         strcpy(d, "&lt;");
 299                         d += 4;
 300                         break;
 301
 302                 case '>':
 303                         strcpy(d, "&gt;");
 304                         d += 4;
 305                         break;
 306
 307                 case '&':
 308                         strcpy(d, "&amp;");
 309                         d += 5;
 310                         break;
 311
 312                 default:
 313                         *d++ = s[i];
 314                 }
 315         }
 316
 317         *d = 0;
 318
 319         return ret;
 320 }
 321
 322
 323 /***************************************************************************
 324 like strdup() but quotes a wide range of characters
 325   ***************************************************************************/
 326 char *urlquote(char *s)
 327 {
 328         int i, n=0;
 329         int len;
 330         char *ret;
 331         char *d;
 332         char *qlist = "\"\n\r'&<> \t+;";
 333
 334         if (!s) return strdup("");
 335
 336         len = strlen(s);
 337
 338         for (i=0;i<len;i++)
 339                 if (strchr(qlist, s[i])) n++;
 340
 341         ret = malloc(len + n*2 + 1);
 342
 343         if (!ret) return NULL;
 344
 345         d = ret;
 346
 347         for (i=0;i<len;i++) {
 348                 if (strchr(qlist,s[i])) {
 349                         sprintf(d, "%%%02X", (int)s[i]);
 350                         d += 3;
 351                 } else {
 352                         *d++ = s[i];
 353                 }
 354         }
 355
 356         *d = 0;
 357
 358         return ret;
 359 }
 360
 361
 362 /***************************************************************************
 363 like strdup() but quotes " characters
 364   ***************************************************************************/
 365 char *quotequotes(char *s)
 366 {
 367         int i, n=0;
 368         int len;
 369         char *ret;
 370         char *d;
 371
 372         if (!s) return strdup("");
 373
 374         len = strlen(s);
 375
 376         for (i=0;i<len;i++)
 377                 if (s[i] == '"')
 378                         n++;
 379
 380         ret = malloc(len + n*6 + 1);
 381
 382         if (!ret) return NULL;
 383
 384         d = ret;
 385
 386         for (i=0;i<len;i++) {
 387                 switch (s[i]) {
 388                 case '"':
 389                         strcpy(d, "&quot;");
 390                         d += 6;
 391                         break;
 392
 393                 default:
 394                         *d++ = s[i];
 395                 }
 396         }
 397
 398         *d = 0;
 399
 400         return ret;
 401 }
 402
 403
 404 /***************************************************************************
 405 quote spaces in a buffer
 406   ***************************************************************************/
 407 void quote_spaces(char *buf)
 408 {
 409         while (*buf) {
 410                 if (*buf == ' ') *buf = '+';
 411                 buf++;
 412         }
 413 }
 414
 415
 416
 417 /***************************************************************************
 418 tell a browser about a fatal error in the http processing
 419   ***************************************************************************/
 420 static void cgi_setup_error(char *err, char *header, char *info)
 421 {
 422         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);
 423         exit(0);
 424 }
 425
 426
 427 /***************************************************************************
 428 decode a base64 string in-place - simple and slow algorithm
 429   ***************************************************************************/
 430 static void base64_decode(char *s)
 431 {
 432         char *b64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
 433         int bit_offset, byte_offset, idx, i;
 434         unsigned char *d = (unsigned char *)s;
 435         char *p;
 436
 437         i=0;
 438
 439         while (*s && (p=strchr(b64,*s))) {
 440                 idx = (int)(p - b64);
 441                 byte_offset = (i*6)/8;
 442                 bit_offset = (i*6)%8;
 443                 d[byte_offset] &= ~((1<<(8-bit_offset))-1);
 444                 if (bit_offset < 3) {
 445                         d[byte_offset] |= (idx << (2-bit_offset));
 446                 } else {
 447                         d[byte_offset] |= (idx >> (bit_offset-2));
 448                         d[byte_offset+1] = 0;
 449                         d[byte_offset+1] |= (idx << (8-(bit_offset-2))) & 0xFF;
 450                 }
 451                 s++; i++;
 452         }
 453 }
 454
 455
 456 /***************************************************************************
 457 handle a http authentication line
 458   ***************************************************************************/
 459 static int cgi_handle_authorization(char *line)
 460 {
 461         char *p, *user, *pass;
 462         struct passwd *pwd;
 463         int ret=0;
 464
 465         if (strncasecmp(line,"Basic ", 6)) {
 466                 cgi_setup_error("401 Bad Authorization", "",
 467                                 "Only basic authorization is understood");
 468         }
 469         line += 6;
 470         while (line[0] == ' ') line++;
 471         base64_decode(line);
 472         if (!(p=strchr(line,':'))) {
 473                 cgi_setup_error("401 Bad Authorization", "",
 474                                 "username/password must be supplied");
 475         }
 476         *p = 0;
 477         user = line;
 478         pass = p+1;
 479
 480         /* currently only allow connections as root */
 481         if (strcasecmp(user,"root")) {
 482                 cgi_setup_error("401 Bad Authorization", "",
 483                                 "incorrect username/password");
 484         }
 485
 486         pwd = getpwnam(user);
 487
 488         if (!strcmp((char *)crypt(pass, pwd->pw_passwd),pwd->pw_passwd)) {
 489                 ret = 1;
 490         }
 491
 492         memset(pass, 0, strlen(pass));
 493
 494         return ret;
 495 }
 496
 497
 498 /***************************************************************************
 499 handle a file download
 500   ***************************************************************************/
 501 static void cgi_download(char *file)
 502 {
 503         struct stat st;
 504         char buf[1024];
 505         int fd, l, i;
 506         char *p;
 507
 508         /* sanitise the filename */
 509         for (i=0;file[i];i++) {
 510                 if (!isalnum(file[i]) && !strchr("/.-_", file[i])) {
 511                         cgi_setup_error("404 File Not Found","",
 512                                         "Illegal character in filename");
 513                 }
 514         }
 515
 516         if (!file_exist(file, &st)) {
 517                 cgi_setup_error("404 File Not Found","",
 518                                 "The requested file was not found");
 519         }
 520         fd = open(file,O_RDONLY);
 521         if (fd == -1) {
 522                 cgi_setup_error("404 File Not Found","",
 523                                 "The requested file was not found");
 524         }
 525         printf("HTTP/1.1 200 OK\r\n");
 526         if ((p=strrchr(file,'.'))) {
 527                 if (strcmp(p,".gif")==0 || strcmp(p,".jpg")==0) {
 528                         printf("Content-Type: image/gif\r\n");
 529                 } else {
 530                         printf("Content-Type: text/html\r\n");
 531                 }
 532         }
 533         printf("Content-Length: %d\r\n\r\n", (int)st.st_size);
 534         while ((l=read(fd,buf,sizeof(buf)))>0) {
 535                 fwrite(buf, 1, l, stdout);
 536         }
 537         close(fd);
 538         exit(0);
 539 }
 540
 541
 542 /***************************************************************************
 543 setup the cgi framework, handling the possability that this program is either
 544 run as a true cgi program by a web browser or is itself a mini web server
 545   ***************************************************************************/
 546 void cgi_setup(char *rootdir, int auth_required)
 547 {
 548         int authenticated = 0;
 549         char line[1024];
 550         char *url=NULL;
 551         char *p;
 552
 553         if (chdir(rootdir)) {
 554                 cgi_setup_error("400 Server Error", "",
 555                                 "chdir failed - the server is not configured correctly");
 556         }
 557
 558         if (getenv("CONTENT_LENGTH") || getenv("REQUEST_METHOD")) {
 559                 /* assume we are running under a real web server */
 560                 return;
 561         }
 562
 563         /* we are a mini-web server. We need to read the request from stdin
 564            and handle authentication etc */
 565         while (fgets(line, sizeof(line)-1, stdin)) {
 566                 if (line[0] == '\r' || line[0] == '\n') break;
 567                 if (strncasecmp(line,"GET ", 4)==0) {
 568                         request_get = 1;
 569                         url = strdup(&line[4]);
 570                 } else if (strncasecmp(line,"POST ", 5)==0) {
 571                         request_post = 1;
 572                         url = strdup(&line[5]);
 573                 } else if (strncasecmp(line,"PUT ", 4)==0) {
 574                         cgi_setup_error("400 Bad Request", "",
 575                                         "This server does not accept PUT requests");
 576                 } else if (strncasecmp(line,"Authorization: ", 15)==0) {
 577                         authenticated = cgi_handle_authorization(&line[15]);
 578                 } else if (strncasecmp(line,"Content-Length: ", 16)==0) {
 579                         content_length = atoi(&line[16]);
 580                 }
 581                 /* ignore all other requests! */
 582         }
 583
 584         if (auth_required && !authenticated) {
 585                 cgi_setup_error("401 Authorization Required",
 586                                 "WWW-Authenticate: Basic realm=\"root\"\r\n",
 587                                 "You must be authenticated to use this service");
 588         }
 589
 590         if (!url) {
 591                 cgi_setup_error("400 Bad Request", "",
 592                                 "You must specify a GET or POST request");
 593         }
 594
 595         /* trim the URL */
 596         if ((p = strchr(url,' ')) || (p=strchr(url,'\t'))) {
 597                 *p = 0;
 598         }
 599         while (*url && strchr("\r\n",url[strlen(url)-1])) {
 600                 url[strlen(url)-1] = 0;
 601         }
 602
 603         /* anything following a ? in the URL is part of the query string */
 604         if ((p=strchr(url,'?'))) {
 605                 query_string = p+1;
 606                 *p = 0;
 607         }
 608
 609         if (strstr(url+1,"..")==0 && file_exist(url+1)) {
 610                 cgi_download(url+1);
 611         }
 612
 613         printf("HTTP/1.1 200 OK\r\nConnection: close\r\n");
 614
 615         baseurl = url+1;
 616 }
 617
 618
 619 /***************************************************************************
 620 return the current pages URL
 621   ***************************************************************************/
 622 char *cgi_baseurl(void)
 623 {
 624         return baseurl;
 625 }