Annotation of embedaddon/curl/lib/dotdot.c, revision 1.1
1.1 ! misho 1: /***************************************************************************
! 2: * _ _ ____ _
! 3: * Project ___| | | | _ \| |
! 4: * / __| | | | |_) | |
! 5: * | (__| |_| | _ <| |___
! 6: * \___|\___/|_| \_\_____|
! 7: *
! 8: * Copyright (C) 1998 - 2019, Daniel Stenberg, <daniel@haxx.se>, et al.
! 9: *
! 10: * This software is licensed as described in the file COPYING, which
! 11: * you should have received as part of this distribution. The terms
! 12: * are also available at https://curl.haxx.se/docs/copyright.html.
! 13: *
! 14: * You may opt to use, copy, modify, merge, publish, distribute and/or sell
! 15: * copies of the Software, and permit persons to whom the Software is
! 16: * furnished to do so, under the terms of the COPYING file.
! 17: *
! 18: * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
! 19: * KIND, either express or implied.
! 20: *
! 21: ***************************************************************************/
! 22:
! 23: #include "curl_setup.h"
! 24:
! 25: #include <curl/curl.h>
! 26:
! 27: #include "dotdot.h"
! 28: #include "curl_memory.h"
! 29:
! 30: /* The last #include file should be: */
! 31: #include "memdebug.h"
! 32:
! 33: /*
! 34: * "Remove Dot Segments"
! 35: * https://tools.ietf.org/html/rfc3986#section-5.2.4
! 36: */
! 37:
! 38: /*
! 39: * Curl_dedotdotify()
! 40: * @unittest: 1395
! 41: *
! 42: * This function gets a zero-terminated path with dot and dotdot sequences
! 43: * passed in and strips them off according to the rules in RFC 3986 section
! 44: * 5.2.4.
! 45: *
! 46: * The function handles a query part ('?' + stuff) appended but it expects
! 47: * that fragments ('#' + stuff) have already been cut off.
! 48: *
! 49: * RETURNS
! 50: *
! 51: * an allocated dedotdotified output string
! 52: */
! 53: char *Curl_dedotdotify(const char *input)
! 54: {
! 55: size_t inlen = strlen(input);
! 56: char *clone;
! 57: size_t clen = inlen; /* the length of the cloned input */
! 58: char *out = malloc(inlen + 1);
! 59: char *outptr;
! 60: char *orgclone;
! 61: char *queryp;
! 62: if(!out)
! 63: return NULL; /* out of memory */
! 64:
! 65: *out = 0; /* zero terminates, for inputs like "./" */
! 66:
! 67: /* get a cloned copy of the input */
! 68: clone = strdup(input);
! 69: if(!clone) {
! 70: free(out);
! 71: return NULL;
! 72: }
! 73: orgclone = clone;
! 74: outptr = out;
! 75:
! 76: if(!*clone) {
! 77: /* zero length string, return that */
! 78: free(out);
! 79: return clone;
! 80: }
! 81:
! 82: /*
! 83: * To handle query-parts properly, we must find it and remove it during the
! 84: * dotdot-operation and then append it again at the end to the output
! 85: * string.
! 86: */
! 87: queryp = strchr(clone, '?');
! 88: if(queryp)
! 89: *queryp = 0;
! 90:
! 91: do {
! 92:
! 93: /* A. If the input buffer begins with a prefix of "../" or "./", then
! 94: remove that prefix from the input buffer; otherwise, */
! 95:
! 96: if(!strncmp("./", clone, 2)) {
! 97: clone += 2;
! 98: clen -= 2;
! 99: }
! 100: else if(!strncmp("../", clone, 3)) {
! 101: clone += 3;
! 102: clen -= 3;
! 103: }
! 104:
! 105: /* B. if the input buffer begins with a prefix of "/./" or "/.", where
! 106: "." is a complete path segment, then replace that prefix with "/" in
! 107: the input buffer; otherwise, */
! 108: else if(!strncmp("/./", clone, 3)) {
! 109: clone += 2;
! 110: clen -= 2;
! 111: }
! 112: else if(!strcmp("/.", clone)) {
! 113: clone[1]='/';
! 114: clone++;
! 115: clen -= 1;
! 116: }
! 117:
! 118: /* C. if the input buffer begins with a prefix of "/../" or "/..", where
! 119: ".." is a complete path segment, then replace that prefix with "/" in
! 120: the input buffer and remove the last segment and its preceding "/" (if
! 121: any) from the output buffer; otherwise, */
! 122:
! 123: else if(!strncmp("/../", clone, 4)) {
! 124: clone += 3;
! 125: clen -= 3;
! 126: /* remove the last segment from the output buffer */
! 127: while(outptr > out) {
! 128: outptr--;
! 129: if(*outptr == '/')
! 130: break;
! 131: }
! 132: *outptr = 0; /* zero-terminate where it stops */
! 133: }
! 134: else if(!strcmp("/..", clone)) {
! 135: clone[2]='/';
! 136: clone += 2;
! 137: clen -= 2;
! 138: /* remove the last segment from the output buffer */
! 139: while(outptr > out) {
! 140: outptr--;
! 141: if(*outptr == '/')
! 142: break;
! 143: }
! 144: *outptr = 0; /* zero-terminate where it stops */
! 145: }
! 146:
! 147: /* D. if the input buffer consists only of "." or "..", then remove
! 148: that from the input buffer; otherwise, */
! 149:
! 150: else if(!strcmp(".", clone) || !strcmp("..", clone)) {
! 151: *clone = 0;
! 152: *out = 0;
! 153: }
! 154:
! 155: else {
! 156: /* E. move the first path segment in the input buffer to the end of
! 157: the output buffer, including the initial "/" character (if any) and
! 158: any subsequent characters up to, but not including, the next "/"
! 159: character or the end of the input buffer. */
! 160:
! 161: do {
! 162: *outptr++ = *clone++;
! 163: clen--;
! 164: } while(*clone && (*clone != '/'));
! 165: *outptr = 0;
! 166: }
! 167:
! 168: } while(*clone);
! 169:
! 170: if(queryp) {
! 171: size_t qlen;
! 172: /* There was a query part, append that to the output. The 'clone' string
! 173: may now have been altered so we copy from the original input string
! 174: from the correct index. */
! 175: size_t oindex = queryp - orgclone;
! 176: qlen = strlen(&input[oindex]);
! 177: memcpy(outptr, &input[oindex], qlen + 1); /* include the end zero byte */
! 178: }
! 179:
! 180: free(orgclone);
! 181: return out;
! 182: }
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