URL: update "file:" URL handling (25634611) · Commits · CYBER - Cyber Security / TS 103 523 MSP / TLMSP / TLMSP curl

lib/url.c

+78 −43

Original line number	Diff line number	Diff line
		@@ -2039,6 +2039,14 @@ static CURLcode parseurlandfillconn(struct Curl_easy *data,
		('A' <= str[0] && str[0] <= 'Z')) && \
		(str[1] == ':'))

		/* MSDOS/Windows style drive prefix, optionally with
		* a '\|' instead of ':', followed by a slash or NUL */
		#define STARTS_WITH_URL_DRIVE_PREFIX(str) \
		((('a' <= (str)[0] && (str)[0] <= 'z') \|\| \
		('A' <= (str)[0] && (str)[0] <= 'Z')) && \
		((str)[1] == ':' \|\| (str)[1] == '\|') && \
		((str)[2] == '/' \|\| (str)[2] == 0))

		/* Don't mistake a drive letter for a scheme if the default protocol is file.
		curld --proto-default file c:/foo/bar.txt */
		if(STARTS_WITH_DRIVE_PREFIX(data->change.url) &&
		@@ -2071,63 +2079,90 @@ static CURLcode parseurlandfillconn(struct Curl_easy *data,
		return CURLE_URL_MALFORMAT;
		}

		if(url_has_scheme && path[0] == '/' && path[1] == '/') {
		/* Allow omitted hostname (e.g. file:/<path>). This is not strictly
		* speaking a valid file: URL by RFC 1738, but treating file:/<path> as
		* file://localhost/<path> is similar to how other schemes treat missing
		* hostnames. See RFC 1808. */

		/* This cannot be done with strcpy() in a portable manner, since the
		memory areas overlap! */
		memmove(path, path + 2, strlen(path + 2) + 1);
		if(url_has_scheme && path[0] == '/' && path[1] == '/' &&
		path[2] == '/' && path[3] == '/') {
		/* This appears to be a UNC string (usually indicating a SMB share).
		* We don't do SMB in file: URLs. (TODO?)
		*/
		failf(data, "SMB shares are not supported in file: URLs.");
		return CURLE_URL_MALFORMAT;
		}

		/* Extra handling URLs with an authority component (i.e. that start with
		* "file://")
		*
		* We allow omitted hostname (e.g. file:/<path>) -- valid according to
		* RFC 8089, but not the (current) WHAT-WG URL spec.
		*/
		if(url_has_scheme && path[0] == '/' && path[1] == '/') {
		/* swallow the two slashes */
		char *ptr = &path[2];

		/*
		* we deal with file://<host>/<path> differently since it supports no
		* hostname other than "localhost" and "127.0.0.1", which is unique among
		* the URL protocols specified in RFC 1738
		* According to RFC 8089, a file: URL can be reliably dereferenced if:
		*
		* o it has no/blank hostname, or
		*
		* o the hostname matches "localhost" (case-insensitively), or
		*
		* o the hostname is a FQDN that resolves to this machine.
		*
		* For brevity, we only consider URLs with empty, "localhost", or
		* "127.0.0.1" hostnames as local.
		*
		* Additionally, there is an exception for URLs with a Windows drive
		* letter in the authority (which was accidentally omitted from RFC 8089
		* Appendix E, but believe me, it was meant to be there. --MK)
		*/
		if(path[0] != '/' && !STARTS_WITH_DRIVE_PREFIX(path)) {
		if(ptr[0] != '/' && !STARTS_WITH_URL_DRIVE_PREFIX(ptr)) {
		/* the URL includes a host name, it must match "localhost" or
		"127.0.0.1" to be valid */
		char *ptr;
		if(!checkprefix("localhost/", path) &&
		!checkprefix("127.0.0.1/", path)) {
		if(!checkprefix("localhost/", ptr) &&
		!checkprefix("127.0.0.1/", ptr)) {
		failf(data, "Invalid file://hostname/, "
		"expected localhost or 127.0.0.1 or none");
		return CURLE_URL_MALFORMAT;
		}
		ptr = &path[9]; /* now points to the slash after the host */

		/* there was a host name and slash present

		RFC1738 (section 3.1, page 5) says:

		The rest of the locator consists of data specific to the scheme,
		and is known as the "url-path". It supplies the details of how the
		specified resource can be accessed. Note that the "/" between the
		host (or port) and the url-path is NOT part of the url-path.
		ptr += 9; /* now points to the slash after the host */
		}

		As most agents use file://localhost/foo to get '/foo' although the
		slash preceding foo is a separator and not a slash for the path,
		a URL as file://localhost//foo must be valid as well, to refer to
		the same file with an absolute path.
		/*
		* RFC 8089, Appendix D, Section D.1, says:
		*
		* > In a POSIX file system, the root of the file system is represented
		* > as a directory with a zero-length name, usually written as "/"; the
		* > presence of this root in a file URI can be taken as given by the
		* > initial slash in the "path-absolute" rule.
		*
		* i.e. the first slash is part of the path.
		*
		* However in RFC 1738 the "/" between the host (or port) and the
		* URL-path was NOT part of the URL-path. Any agent that followed the
		* older spec strictly, and wanted to refer to a file with an absolute
		* path, would have included a second slash. So if there are two
		* slashes, swallow one.
		*/

		if('/' == ptr[1])
		/* if there was two slashes, we skip the first one as that is then
		used truly as a separator */
		if('/' == ptr[1]) /* note: the only way ptr[0]!='/' is if ptr[1]==':' */
		ptr++;

		/* This cannot be made with strcpy, as the memory chunks overlap! */
		/* This cannot be done with strcpy, as the memory chunks overlap! */
		memmove(path, ptr, strlen(ptr) + 1);
		}

		#if !defined(MSDOS) && !defined(WIN32) && !defined(__CYGWIN__)
		if(STARTS_WITH_DRIVE_PREFIX(path)) {
		/* Don't allow Windows drive letters when not in Windows.
		* This catches both "file:/c:" and "file:c:" */
		if(('/' == path[0] && STARTS_WITH_URL_DRIVE_PREFIX(&path[1])) \|\|
		STARTS_WITH_URL_DRIVE_PREFIX(path)) {
		failf(data, "File drive letters are only accepted in MSDOS/Windows.");
		return CURLE_URL_MALFORMAT;
		}
		#else
		/* If the path starts with a slash and a drive letter, ditch the slash */
		if('/' == path[0] && STARTS_WITH_URL_DRIVE_PREFIX(&path[1])) {
		/* This cannot be done with strcpy, as the memory chunks overlap! */
		memmove(path, &path[1], strlen(&path[1]) + 1);
		}
		#endif

		protop = "file"; /* protocol string */

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