git/urlmatch.c
brian m. carlson 46fd7b3900 credential: allow wildcard patterns when matching config
In some cases, a user will want to use a specific credential helper for
a wildcard pattern, such as https://*.corp.example.com.  We have code
that handles this already with the urlmatch code, so let's use that
instead of our custom code.

Since the urlmatch code is a superset of our current matching in terms
of capabilities, there shouldn't be any cases of things that matched
previously that don't match now.  However, in addition to wildcard
matching, we now use partial path matching, which can cause slightly
different behavior in the case that a helper applies to the prefix
(considering path components) of the remote URL.  While different, this
is probably the behavior people were wanting anyway.

Since we're using the urlmatch code, we need to encode the components
we've gotten into a URL to match, so add a function to percent-encode
data and format the URL with it.  We now also no longer need to the
custom code to match URLs, so let's remove it.

Additionally, the urlmatch code always looks for the best match, whereas
we want all matches for credential helpers to preserve existing
behavior.  Let's add an optional field, select_fn, that lets us control
which items we want (in this case, all of them) and default it to the
best-match code that already exists for other users.

Signed-off-by: brian m. carlson <bk2204@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-20 13:05:43 -08:00

610 lines
18 KiB
C

#include "cache.h"
#include "urlmatch.h"
#define URL_ALPHA "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
#define URL_DIGIT "0123456789"
#define URL_ALPHADIGIT URL_ALPHA URL_DIGIT
#define URL_SCHEME_CHARS URL_ALPHADIGIT "+.-"
#define URL_HOST_CHARS URL_ALPHADIGIT ".-[:]" /* IPv6 literals need [:] */
#define URL_UNSAFE_CHARS " <>\"%{}|\\^`" /* plus 0x00-0x1F,0x7F-0xFF */
#define URL_GEN_RESERVED ":/?#[]@"
#define URL_SUB_RESERVED "!$&'()*+,;="
#define URL_RESERVED URL_GEN_RESERVED URL_SUB_RESERVED /* only allowed delims */
static int append_normalized_escapes(struct strbuf *buf,
const char *from,
size_t from_len,
const char *esc_extra,
const char *esc_ok)
{
/*
* Append to strbuf 'buf' characters from string 'from' with length
* 'from_len' while unescaping characters that do not need to be escaped
* and escaping characters that do. The set of characters to escape
* (the complement of which is unescaped) starts out as the RFC 3986
* unsafe characters (0x00-0x1F,0x7F-0xFF," <>\"#%{}|\\^`"). If
* 'esc_extra' is not NULL, those additional characters will also always
* be escaped. If 'esc_ok' is not NULL, those characters will be left
* escaped if found that way, but will not be unescaped otherwise (used
* for delimiters). If a %-escape sequence is encountered that is not
* followed by 2 hexadecimal digits, the sequence is invalid and
* false (0) will be returned. Otherwise true (1) will be returned for
* success.
*
* Note that all %-escape sequences will be normalized to UPPERCASE
* as indicated in RFC 3986. Unless included in esc_extra or esc_ok
* alphanumerics and "-._~" will always be unescaped as per RFC 3986.
*/
while (from_len) {
int ch = *from++;
int was_esc = 0;
from_len--;
if (ch == '%') {
if (from_len < 2)
return 0;
ch = hex2chr(from);
if (ch < 0)
return 0;
from += 2;
from_len -= 2;
was_esc = 1;
}
if ((unsigned char)ch <= 0x1F || (unsigned char)ch >= 0x7F ||
strchr(URL_UNSAFE_CHARS, ch) ||
(esc_extra && strchr(esc_extra, ch)) ||
(was_esc && strchr(esc_ok, ch)))
strbuf_addf(buf, "%%%02X", (unsigned char)ch);
else
strbuf_addch(buf, ch);
}
return 1;
}
static const char *end_of_token(const char *s, int c, size_t n)
{
const char *next = memchr(s, c, n);
if (!next)
next = s + n;
return next;
}
static int match_host(const struct url_info *url_info,
const struct url_info *pattern_info)
{
const char *url = url_info->url + url_info->host_off;
const char *pat = pattern_info->url + pattern_info->host_off;
int url_len = url_info->host_len;
int pat_len = pattern_info->host_len;
while (url_len && pat_len) {
const char *url_next = end_of_token(url, '.', url_len);
const char *pat_next = end_of_token(pat, '.', pat_len);
if (pat_next == pat + 1 && pat[0] == '*')
/* wildcard matches anything */
;
else if ((pat_next - pat) == (url_next - url) &&
!memcmp(url, pat, url_next - url))
/* the components are the same */
;
else
return 0; /* found an unmatch */
if (url_next < url + url_len)
url_next++;
url_len -= url_next - url;
url = url_next;
if (pat_next < pat + pat_len)
pat_next++;
pat_len -= pat_next - pat;
pat = pat_next;
}
return (!url_len && !pat_len);
}
static char *url_normalize_1(const char *url, struct url_info *out_info, char allow_globs)
{
/*
* Normalize NUL-terminated url using the following rules:
*
* 1. Case-insensitive parts of url will be converted to lower case
* 2. %-encoded characters that do not need to be will be unencoded
* 3. Characters that are not %-encoded and must be will be encoded
* 4. All %-encodings will be converted to upper case hexadecimal
* 5. Leading 0s are removed from port numbers
* 6. If the default port for the scheme is given it will be removed
* 7. A path part (including empty) not starting with '/' has one added
* 8. Any dot segments (. or ..) in the path are resolved and removed
* 9. IPv6 host literals are allowed (but not normalized or validated)
*
* The rules are based on information in RFC 3986.
*
* Please note this function requires a full URL including a scheme
* and host part (except for file: URLs which may have an empty host).
*
* The return value is a newly allocated string that must be freed
* or NULL if the url is not valid.
*
* If out_info is non-NULL, the url and err fields therein will always
* be set. If a non-NULL value is returned, it will be stored in
* out_info->url as well, out_info->err will be set to NULL and the
* other fields of *out_info will also be filled in. If a NULL value
* is returned, NULL will be stored in out_info->url and out_info->err
* will be set to a brief, translated, error message, but no other
* fields will be filled in.
*
* This is NOT a URL validation function. Full URL validation is NOT
* performed. Some invalid host names are passed through this function
* undetected. However, most all other problems that make a URL invalid
* will be detected (including a missing host for non file: URLs).
*/
size_t url_len = strlen(url);
struct strbuf norm;
size_t spanned;
size_t scheme_len, user_off=0, user_len=0, passwd_off=0, passwd_len=0;
size_t host_off=0, host_len=0, port_off=0, port_len=0, path_off, path_len, result_len;
const char *slash_ptr, *at_ptr, *colon_ptr, *path_start;
char *result;
/*
* Copy lowercased scheme and :// suffix, %-escapes are not allowed
* First character of scheme must be URL_ALPHA
*/
spanned = strspn(url, URL_SCHEME_CHARS);
if (!spanned || !isalpha(url[0]) || spanned + 3 > url_len ||
url[spanned] != ':' || url[spanned+1] != '/' || url[spanned+2] != '/') {
if (out_info) {
out_info->url = NULL;
out_info->err = _("invalid URL scheme name or missing '://' suffix");
}
return NULL; /* Bad scheme and/or missing "://" part */
}
strbuf_init(&norm, url_len);
scheme_len = spanned;
spanned += 3;
url_len -= spanned;
while (spanned--)
strbuf_addch(&norm, tolower(*url++));
/*
* Copy any username:password if present normalizing %-escapes
*/
at_ptr = strchr(url, '@');
slash_ptr = url + strcspn(url, "/?#");
if (at_ptr && at_ptr < slash_ptr) {
user_off = norm.len;
if (at_ptr > url) {
if (!append_normalized_escapes(&norm, url, at_ptr - url,
"", URL_RESERVED)) {
if (out_info) {
out_info->url = NULL;
out_info->err = _("invalid %XX escape sequence");
}
strbuf_release(&norm);
return NULL;
}
colon_ptr = strchr(norm.buf + scheme_len + 3, ':');
if (colon_ptr) {
passwd_off = (colon_ptr + 1) - norm.buf;
passwd_len = norm.len - passwd_off;
user_len = (passwd_off - 1) - (scheme_len + 3);
} else {
user_len = norm.len - (scheme_len + 3);
}
}
strbuf_addch(&norm, '@');
url_len -= (++at_ptr - url);
url = at_ptr;
}
/*
* Copy the host part excluding any port part, no %-escapes allowed
*/
if (!url_len || strchr(":/?#", *url)) {
/* Missing host invalid for all URL schemes except file */
if (strncmp(norm.buf, "file:", 5)) {
if (out_info) {
out_info->url = NULL;
out_info->err = _("missing host and scheme is not 'file:'");
}
strbuf_release(&norm);
return NULL;
}
} else {
host_off = norm.len;
}
colon_ptr = slash_ptr - 1;
while (colon_ptr > url && *colon_ptr != ':' && *colon_ptr != ']')
colon_ptr--;
if (*colon_ptr != ':') {
colon_ptr = slash_ptr;
} else if (!host_off && colon_ptr < slash_ptr && colon_ptr + 1 != slash_ptr) {
/* file: URLs may not have a port number */
if (out_info) {
out_info->url = NULL;
out_info->err = _("a 'file:' URL may not have a port number");
}
strbuf_release(&norm);
return NULL;
}
if (allow_globs)
spanned = strspn(url, URL_HOST_CHARS "*");
else
spanned = strspn(url, URL_HOST_CHARS);
if (spanned < colon_ptr - url) {
/* Host name has invalid characters */
if (out_info) {
out_info->url = NULL;
out_info->err = _("invalid characters in host name");
}
strbuf_release(&norm);
return NULL;
}
while (url < colon_ptr) {
strbuf_addch(&norm, tolower(*url++));
url_len--;
}
/*
* Check the port part and copy if not the default (after removing any
* leading 0s); no %-escapes allowed
*/
if (colon_ptr < slash_ptr) {
/* skip the ':' and leading 0s but not the last one if all 0s */
url++;
url += strspn(url, "0");
if (url == slash_ptr && url[-1] == '0')
url--;
if (url == slash_ptr) {
/* Skip ":" port with no number, it's same as default */
} else if (slash_ptr - url == 2 &&
!strncmp(norm.buf, "http:", 5) &&
!strncmp(url, "80", 2)) {
/* Skip http :80 as it's the default */
} else if (slash_ptr - url == 3 &&
!strncmp(norm.buf, "https:", 6) &&
!strncmp(url, "443", 3)) {
/* Skip https :443 as it's the default */
} else {
/*
* Port number must be all digits with leading 0s removed
* and since all the protocols we deal with have a 16-bit
* port number it must also be in the range 1..65535
* 0 is not allowed because that means "next available"
* on just about every system and therefore cannot be used
*/
unsigned long pnum = 0;
spanned = strspn(url, URL_DIGIT);
if (spanned < slash_ptr - url) {
/* port number has invalid characters */
if (out_info) {
out_info->url = NULL;
out_info->err = _("invalid port number");
}
strbuf_release(&norm);
return NULL;
}
if (slash_ptr - url <= 5)
pnum = strtoul(url, NULL, 10);
if (pnum == 0 || pnum > 65535) {
/* port number not in range 1..65535 */
if (out_info) {
out_info->url = NULL;
out_info->err = _("invalid port number");
}
strbuf_release(&norm);
return NULL;
}
strbuf_addch(&norm, ':');
port_off = norm.len;
strbuf_add(&norm, url, slash_ptr - url);
port_len = slash_ptr - url;
}
url_len -= slash_ptr - colon_ptr;
url = slash_ptr;
}
if (host_off)
host_len = norm.len - host_off - (port_len ? port_len + 1 : 0);
/*
* Now copy the path resolving any . and .. segments being careful not
* to corrupt the URL by unescaping any delimiters, but do add an
* initial '/' if it's missing and do normalize any %-escape sequences.
*/
path_off = norm.len;
path_start = norm.buf + path_off;
strbuf_addch(&norm, '/');
if (*url == '/') {
url++;
url_len--;
}
for (;;) {
const char *seg_start;
size_t seg_start_off = norm.len;
const char *next_slash = url + strcspn(url, "/?#");
int skip_add_slash = 0;
/*
* RFC 3689 indicates that any . or .. segments should be
* unescaped before being checked for.
*/
if (!append_normalized_escapes(&norm, url, next_slash - url, "",
URL_RESERVED)) {
if (out_info) {
out_info->url = NULL;
out_info->err = _("invalid %XX escape sequence");
}
strbuf_release(&norm);
return NULL;
}
seg_start = norm.buf + seg_start_off;
if (!strcmp(seg_start, ".")) {
/* ignore a . segment; be careful not to remove initial '/' */
if (seg_start == path_start + 1) {
strbuf_setlen(&norm, norm.len - 1);
skip_add_slash = 1;
} else {
strbuf_setlen(&norm, norm.len - 2);
}
} else if (!strcmp(seg_start, "..")) {
/*
* ignore a .. segment and remove the previous segment;
* be careful not to remove initial '/' from path
*/
const char *prev_slash = norm.buf + norm.len - 3;
if (prev_slash == path_start) {
/* invalid .. because no previous segment to remove */
if (out_info) {
out_info->url = NULL;
out_info->err = _("invalid '..' path segment");
}
strbuf_release(&norm);
return NULL;
}
while (*--prev_slash != '/') {}
if (prev_slash == path_start) {
strbuf_setlen(&norm, prev_slash - norm.buf + 1);
skip_add_slash = 1;
} else {
strbuf_setlen(&norm, prev_slash - norm.buf);
}
}
url_len -= next_slash - url;
url = next_slash;
/* if the next char is not '/' done with the path */
if (*url != '/')
break;
url++;
url_len--;
if (!skip_add_slash)
strbuf_addch(&norm, '/');
}
path_len = norm.len - path_off;
/*
* Now simply copy the rest, if any, only normalizing %-escapes and
* being careful not to corrupt the URL by unescaping any delimiters.
*/
if (*url) {
if (!append_normalized_escapes(&norm, url, url_len, "", URL_RESERVED)) {
if (out_info) {
out_info->url = NULL;
out_info->err = _("invalid %XX escape sequence");
}
strbuf_release(&norm);
return NULL;
}
}
result = strbuf_detach(&norm, &result_len);
if (out_info) {
out_info->url = result;
out_info->err = NULL;
out_info->url_len = result_len;
out_info->scheme_len = scheme_len;
out_info->user_off = user_off;
out_info->user_len = user_len;
out_info->passwd_off = passwd_off;
out_info->passwd_len = passwd_len;
out_info->host_off = host_off;
out_info->host_len = host_len;
out_info->port_off = port_off;
out_info->port_len = port_len;
out_info->path_off = path_off;
out_info->path_len = path_len;
}
return result;
}
char *url_normalize(const char *url, struct url_info *out_info)
{
return url_normalize_1(url, out_info, 0);
}
static size_t url_match_prefix(const char *url,
const char *url_prefix,
size_t url_prefix_len)
{
/*
* url_prefix matches url if url_prefix is an exact match for url or it
* is a prefix of url and the match ends on a path component boundary.
* Both url and url_prefix are considered to have an implicit '/' on the
* end for matching purposes if they do not already.
*
* url must be NUL terminated. url_prefix_len is the length of
* url_prefix which need not be NUL terminated.
*
* The return value is the length of the match in characters (including
* the final '/' even if it's implicit) or 0 for no match.
*
* Passing NULL as url and/or url_prefix will always cause 0 to be
* returned without causing any faults.
*/
if (!url || !url_prefix)
return 0;
if (!url_prefix_len || (url_prefix_len == 1 && *url_prefix == '/'))
return (!*url || *url == '/') ? 1 : 0;
if (url_prefix[url_prefix_len - 1] == '/')
url_prefix_len--;
if (strncmp(url, url_prefix, url_prefix_len))
return 0;
if ((strlen(url) == url_prefix_len) || (url[url_prefix_len] == '/'))
return url_prefix_len + 1;
return 0;
}
static int match_urls(const struct url_info *url,
const struct url_info *url_prefix,
struct urlmatch_item *match)
{
/*
* url_prefix matches url if the scheme, host and port of url_prefix
* are the same as those of url and the path portion of url_prefix
* is the same as the path portion of url or it is a prefix that
* matches at a '/' boundary. If url_prefix contains a user name,
* that must also exactly match the user name in url.
*
* If the user, host, port and path match in this fashion, the returned
* value is the length of the path match including any implicit
* final '/'. For example, "http://me@example.com/path" is matched by
* "http://example.com" with a path length of 1.
*
* If there is a match and exactusermatch is not NULL, then
* *exactusermatch will be set to true if both url and url_prefix
* contained a user name or false if url_prefix did not have a
* user name. If there is no match *exactusermatch is left untouched.
*/
char usermatched = 0;
size_t pathmatchlen;
if (!url || !url_prefix || !url->url || !url_prefix->url)
return 0;
/* check the scheme */
if (url_prefix->scheme_len != url->scheme_len ||
strncmp(url->url, url_prefix->url, url->scheme_len))
return 0; /* schemes do not match */
/* check the user name if url_prefix has one */
if (url_prefix->user_off) {
if (!url->user_off || url->user_len != url_prefix->user_len ||
strncmp(url->url + url->user_off,
url_prefix->url + url_prefix->user_off,
url->user_len))
return 0; /* url_prefix has a user but it's not a match */
usermatched = 1;
}
/* check the host */
if (!match_host(url, url_prefix))
return 0; /* host names do not match */
/* check the port */
if (url_prefix->port_len != url->port_len ||
strncmp(url->url + url->port_off,
url_prefix->url + url_prefix->port_off, url->port_len))
return 0; /* ports do not match */
/* check the path */
pathmatchlen = url_match_prefix(
url->url + url->path_off,
url_prefix->url + url_prefix->path_off,
url_prefix->url_len - url_prefix->path_off);
if (!pathmatchlen)
return 0; /* paths do not match */
if (match) {
match->hostmatch_len = url_prefix->host_len;
match->pathmatch_len = pathmatchlen;
match->user_matched = usermatched;
}
return 1;
}
static int cmp_matches(const struct urlmatch_item *a,
const struct urlmatch_item *b)
{
if (a->hostmatch_len != b->hostmatch_len)
return a->hostmatch_len < b->hostmatch_len ? -1 : 1;
if (a->pathmatch_len != b->pathmatch_len)
return a->pathmatch_len < b->pathmatch_len ? -1 : 1;
if (a->user_matched != b->user_matched)
return b->user_matched ? -1 : 1;
return 0;
}
int urlmatch_config_entry(const char *var, const char *value, void *cb)
{
struct string_list_item *item;
struct urlmatch_config *collect = cb;
struct urlmatch_item matched = {0};
struct url_info *url = &collect->url;
const char *key, *dot;
struct strbuf synthkey = STRBUF_INIT;
int retval;
int (*select_fn)(const struct urlmatch_item *a, const struct urlmatch_item *b) =
collect->select_fn ? collect->select_fn : cmp_matches;
if (!skip_prefix(var, collect->section, &key) || *(key++) != '.') {
if (collect->cascade_fn)
return collect->cascade_fn(var, value, cb);
return 0; /* not interested */
}
dot = strrchr(key, '.');
if (dot) {
char *config_url, *norm_url;
struct url_info norm_info;
config_url = xmemdupz(key, dot - key);
norm_url = url_normalize_1(config_url, &norm_info, 1);
free(config_url);
if (!norm_url)
return 0;
retval = match_urls(url, &norm_info, &matched);
free(norm_url);
if (!retval)
return 0;
key = dot + 1;
}
if (collect->key && strcmp(key, collect->key))
return 0;
item = string_list_insert(&collect->vars, key);
if (!item->util) {
item->util = xcalloc(1, sizeof(matched));
} else {
if (select_fn(&matched, item->util) < 0)
/*
* Our match is worse than the old one,
* we cannot use it.
*/
return 0;
/* Otherwise, replace it with this one. */
}
memcpy(item->util, &matched, sizeof(matched));
strbuf_addstr(&synthkey, collect->section);
strbuf_addch(&synthkey, '.');
strbuf_addstr(&synthkey, key);
retval = collect->collect_fn(synthkey.buf, value, collect->cb);
strbuf_release(&synthkey);
return retval;
}