前言
看师傅们的文章时发现,parse_url出现的次数较多，单纯parse_url解析漏洞的考题也有很多，在此研究一下源码(太菜了看不懂，待日后再补充Orz)
源码
PHPAPI php_url *php_url_parse_ex(char const *str, size_t length)
{
char port_buf[6];
php_url *ret = ecalloc(1, sizeof(php_url));
char const *s, *e, *p, *pp, *ue;
s = str;
ue = s + length;
/* parse scheme */
if ((e = memchr(s, ':', length)) && e != s) {
/* validate scheme */
p = s;
while (p < e) {
/* scheme = 1*[ lowalpha | digit | "+" | "-" | "." ] */
if (!isalpha(*p) && !isdigit(*p) && *p != '+' && *p != '.' && *p != '-') {
if (e + 1 < ue && e < s + strcspn(s, "?#")) {
goto parse_port;
} else if (s + 1 < ue && *s == '/' && *(s + 1) == '/') { /* relative-scheme URL */
s += 2;
e = 0;
goto parse_host;
} else {
goto just_path;
}
}
p++;
}
if (e + 1 == ue) { /* only scheme is available */
ret->scheme = estrndup(s, (e - s));
php_replace_controlchars_ex(ret->scheme, (e - s));
return ret;
}
/*
* certain schemas like mailto: and zlib: may not have any / after them
* this check ensures we support those.
*/
if (*(e+1) != '/') {
/* check if the data we get is a port this allows us to
* correctly parse things like a.com:80
*/
p = e + 1;
while (p < ue && isdigit(*p)) {
p++;
}
if ((p == ue || *p == '/') && (p - e) < 7) {
goto parse_port;
}
ret->scheme = estrndup(s, (e-s));
php_replace_controlchars_ex(ret->scheme, (e - s));
s = e + 1;
goto just_path;
} else {
ret->scheme = estrndup(s, (e-s));
php_replace_controlchars_ex(ret->scheme, (e - s));
if (e + 2 < ue && *(e + 2) == '/') {
s = e + 3;
if (!strncasecmp("file", ret->scheme, sizeof("file"))) {
if (e + 3 < ue && *(e + 3) == '/') {
/* support windows drive letters as in:
file:///c:/somedir/file.txt
*/
if (e + 5 < ue && *(e + 5) == ':') {
s = e + 4;
}
goto just_path;
}
}
} else {
s = e + 1;
goto just_path;
}
}
} else if (e) { /* no scheme; starts with colon: look for port */
parse_port:
p = e + 1;
pp = p;
while (pp < ue && pp - p < 6 && isdigit(*pp)) {
pp++;
}
if (pp - p > 0 && pp - p < 6 && (pp == ue || *pp == '/')) {
zend_long port;
memcpy(port_buf, p, (pp - p));
port_buf[pp - p] = ' ';
port = ZEND_STRTOL(port_buf, NULL, 10);
if (port > 0 && port <= 65535) {
ret->port = (unsigned short) port;
if (s + 1 < ue && *s == '/' && *(s + 1) == '/') { /* relative-scheme URL */
s += 2;
}
} else {
if (ret->scheme) efree(ret->scheme);
efree(ret);
return NULL;
}
} else if (p == pp && pp == ue) {
if (ret->scheme) efree(ret->scheme);
efree(ret);
return NULL;
} else if (s + 1 < ue && *s == '/' && *(s + 1) == '/') { /* relative-scheme URL */
s += 2;
} else {
goto just_path;
}
} else if (s + 1 < ue && *s == '/' && *(s + 1) == '/') { /* relative-scheme URL */
s += 2;
} else {
goto just_path;
}
parse_host:
/* Binary-safe strcspn(s, "/?#") */
e = ue;
if ((p = memchr(s, '/', e - s))) {
e = p;
}
if ((p = memchr(s, '?', e - s))) {
e = p;
}
if ((p = memchr(s, '#', e - s))) {
e = p;
}
/* check for login and password */
if ((p = zend_memrchr(s, '@', (e-s)))) {
if ((pp = memchr(s, ':', (p-s)))) {
ret->user = estrndup(s, (pp-s));
php_replace_controlchars_ex(ret->user, (pp - s));
pp++;
ret->pass = estrndup(pp, (p-pp));
php_replace_controlchars_ex(ret->pass, (p-pp));
} else {
ret->user = estrndup(s, (p-s));
php_replace_controlchars_ex(ret->user, (p-s));
}
s = p + 1;
}
/* check for port */
if (s < ue && *s == '[' && *(e-1) == ']') {
/* Short circuit portscan,
we're dealing with an
IPv6 embedded address */
p = NULL;
} else {
p = zend_memrchr(s, ':', (e-s));
}
if (p) {
if (!ret->port) {
p++;
if (e-p > 5) { /* port cannot be longer then 5 characters */
if (ret->scheme) efree(ret->scheme);
if (ret->user) efree(ret->user);
if (ret->pass) efree(ret->pass);
efree(ret);
return NULL;
} else if (e - p > 0) {
zend_long port;
memcpy(port_buf, p, (e - p));
port_buf[e - p] = ' ';
port = ZEND_STRTOL(port_buf, NULL, 10);
if (port > 0 && port <= 65535) {
ret->port = (unsigned short)port;
} else {
if (ret->scheme) efree(ret->scheme);
if (ret->user) efree(ret->user);
if (ret->pass) efree(ret->pass);
efree(ret);
return NULL;
}
}
p--;
}
} else {
p = e;
}
/* check if we have a valid host, if we don't reject the string as url */
if ((p-s) < 1) {
if (ret->scheme) efree(ret->scheme);
if (ret->user) efree(ret->user);
if (ret->pass) efree(ret->pass);
efree(ret);
return NULL;
}
ret->host = estrndup(s, (p-s));
php_replace_controlchars_ex(ret->host, (p - s));
if (e == ue) {
return ret;
}
s = e;
just_path:
e = ue;
p = memchr(s, '#', (e - s));
if (p) {
p++;
if (p < e) {
ret->fragment = estrndup(p, (e - p));
php_replace_controlchars_ex(ret->fragment, (e - p));
}
e = p-1;
}
p = memchr(s, '?', (e - s));
if (p) {
p++;
if (p < e) {
ret->query = estrndup(p, (e - p));
php_replace_controlchars_ex(ret->query, (e - p));
}
e = p-1;
}
if (s < e || s == ue) {
ret->path = estrndup(s, (e - s));
php_replace_controlchars_ex(ret->path, (e - s));
}
return ret;
}
/* {{{ proto mixed parse_url(string url, [int url_component])
Parse a URL and return its components */
PHP_FUNCTION(parse_url)
{
char *str;
size_t str_len;
php_url *resource;
zend_long key = -1;
if (zend_parse_parameters(ZEND_NUM_ARGS(), "s|l", &str, &str_len, &key) == FAILURE) {
return;
}
resource = php_url_parse_ex(str, str_len);
if (resource == NULL) {
/* @todo Find a method to determine why php_url_parse_ex() failed */
RETURN_FALSE;
}
分析
- 只要请求的url里不含有冒号(:)就会被当成path解析