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4c5099868e
curl/lib/hsts.c
Daniel Stenberg f0d7318193
strparse: provide access functions 
To access the string and the length without having to directly use the
struct field names. Gives more freedom, flexbility and keeps
implementation specifics out of users' code.

Closes #16386
2025-02-19 12:17:32 +01:00

590 lines
15 KiB
C
Raw Blame History

/***************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
*
* This software is licensed as described in the file COPYING, which
* you should have received as part of this distribution. The terms
* are also available at https://curl.se/docs/copyright.html.
*
* You may opt to use, copy, modify, merge, publish, distribute and/or sell
* copies of the Software, and permit persons to whom the Software is
* furnished to do so, under the terms of the COPYING file.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
* SPDX-License-Identifier: curl
*
***************************************************************************/
/*
* The Strict-Transport-Security header is defined in RFC 6797:
* https://datatracker.ietf.org/doc/html/rfc6797
*/
#include "curl_setup.h"
#if !defined(CURL_DISABLE_HTTP) && !defined(CURL_DISABLE_HSTS)
#include <curl/curl.h>
#include "urldata.h"
#include "llist.h"
#include "hsts.h"
#include "curl_get_line.h"
#include "strcase.h"
#include "sendf.h"
#include "parsedate.h"
#include "fopen.h"
#include "rename.h"
#include "share.h"
#include "strdup.h"
#include "strparse.h"
/* The last 3 #include files should be in this order */
#include "curl_printf.h"
#include "curl_memory.h"
#include "memdebug.h"
#define MAX_HSTS_LINE 4095
#define MAX_HSTS_HOSTLEN 2048
#define MAX_HSTS_DATELEN 256
#define UNLIMITED "unlimited"
#if defined(DEBUGBUILD) || defined(UNITTESTS)
/* to play well with debug builds, we can *set* a fixed time this will
return */
time_t deltatime; /* allow for "adjustments" for unit test purposes */
static time_t hsts_debugtime(void *unused)
{
const char *timestr = getenv("CURL_TIME");
(void)unused;
if(timestr) {
curl_off_t val;
if(!Curl_str_number(&timestr, &val, TIME_T_MAX))
val += (curl_off_t)deltatime;
return (time_t)val;
}
return time(NULL);
}
#undef time
#define time(x) hsts_debugtime(x)
#endif
struct hsts *Curl_hsts_init(void)
{
struct hsts *h = calloc(1, sizeof(struct hsts));
if(h) {
Curl_llist_init(&h->list, NULL);
}
return h;
}
static void hsts_free(struct stsentry *e)
{
free((char *)e->host);
free(e);
}
void Curl_hsts_cleanup(struct hsts **hp)
{
struct hsts *h = *hp;
if(h) {
struct Curl_llist_node *e;
struct Curl_llist_node *n;
for(e = Curl_llist_head(&h->list); e; e = n) {
struct stsentry *sts = Curl_node_elem(e);
n = Curl_node_next(e);
hsts_free(sts);
}
free(h->filename);
free(h);
*hp = NULL;
}
}
static CURLcode hsts_create(struct hsts *h,
const char *hostname,
size_t hlen,
bool subdomains,
curl_off_t expires)
{
DEBUGASSERT(h);
DEBUGASSERT(hostname);
if(hlen && (hostname[hlen - 1] == '.'))
/* strip off any trailing dot */
--hlen;
if(hlen) {
char *duphost;
struct stsentry *sts = calloc(1, sizeof(struct stsentry));
if(!sts)
return CURLE_OUT_OF_MEMORY;
duphost = Curl_memdup0(hostname, hlen);
if(!duphost) {
free(sts);
return CURLE_OUT_OF_MEMORY;
}
sts->host = duphost;
sts->expires = expires;
sts->includeSubDomains = subdomains;
Curl_llist_append(&h->list, sts, &sts->node);
}
return CURLE_OK;
}
CURLcode Curl_hsts_parse(struct hsts *h, const char *hostname,
const char *header)
{
const char *p = header;
curl_off_t expires = 0;
bool gotma = FALSE;
bool gotinc = FALSE;
bool subdomains = FALSE;
struct stsentry *sts;
time_t now = time(NULL);
size_t hlen = strlen(hostname);
if(Curl_host_is_ipnum(hostname))
/* "explicit IP address identification of all forms is excluded."
/ RFC 6797 */
return CURLE_OK;
do {
while(ISBLANK(*p))
p++;
if(strncasecompare("max-age", p, 7)) {
bool quoted = FALSE;
int rc;
if(gotma)
return CURLE_BAD_FUNCTION_ARGUMENT;
p += 7;
while(ISBLANK(*p))
p++;
if(*p++ != '=')
return CURLE_BAD_FUNCTION_ARGUMENT;
while(ISBLANK(*p))
p++;
if(*p == '\"') {
p++;
quoted = TRUE;
}
rc = Curl_str_number(&p, &expires, TIME_T_MAX);
if(rc == STRE_OVERFLOW)
expires = CURL_OFF_T_MAX;
else if(rc)
/* invalid max-age */
return CURLE_BAD_FUNCTION_ARGUMENT;
if(quoted) {
if(*p != '\"')
return CURLE_BAD_FUNCTION_ARGUMENT;
p++;
}
gotma = TRUE;
}
else if(strncasecompare("includesubdomains", p, 17)) {
if(gotinc)
return CURLE_BAD_FUNCTION_ARGUMENT;
subdomains = TRUE;
p += 17;
gotinc = TRUE;
}
else {
/* unknown directive, do a lame attempt to skip */
while(*p && (*p != ';'))
p++;
}
while(ISBLANK(*p))
p++;
if(*p == ';')
p++;
} while(*p);
if(!gotma)
/* max-age is mandatory */
return CURLE_BAD_FUNCTION_ARGUMENT;
if(!expires) {
/* remove the entry if present verbatim (without subdomain match) */
sts = Curl_hsts(h, hostname, hlen, FALSE);
if(sts) {
Curl_node_remove(&sts->node);
hsts_free(sts);
}
return CURLE_OK;
}
if(CURL_OFF_T_MAX - now < expires)
/* would overflow, use maximum value */
expires = CURL_OFF_T_MAX;
else
expires += now;
/* check if it already exists */
sts = Curl_hsts(h, hostname, hlen, FALSE);
if(sts) {
/* just update these fields */
sts->expires = expires;
sts->includeSubDomains = subdomains;
}
else
return hsts_create(h, hostname, hlen, subdomains, expires);
return CURLE_OK;
}
/*
* Return TRUE if the given hostname is currently an HSTS one.
*
* The 'subdomain' argument tells the function if subdomain matching should be
* attempted.
*/
struct stsentry *Curl_hsts(struct hsts *h, const char *hostname,
size_t hlen, bool subdomain)
{
struct stsentry *bestsub = NULL;
if(h) {
time_t now = time(NULL);
struct Curl_llist_node *e;
struct Curl_llist_node *n;
size_t blen = 0;
if((hlen > MAX_HSTS_HOSTLEN) || !hlen)
return NULL;
if(hostname[hlen-1] == '.')
/* remove the trailing dot */
--hlen;
for(e = Curl_llist_head(&h->list); e; e = n) {
struct stsentry *sts = Curl_node_elem(e);
size_t ntail;
n = Curl_node_next(e);
if(sts->expires <= now) {
/* remove expired entries */
Curl_node_remove(&sts->node);
hsts_free(sts);
continue;
}
ntail = strlen(sts->host);
if((subdomain && sts->includeSubDomains) && (ntail < hlen)) {
size_t offs = hlen - ntail;
if((hostname[offs-1] == '.') &&
strncasecompare(&hostname[offs], sts->host, ntail) &&
(ntail > blen)) {
/* save the tail match with the longest tail */
bestsub = sts;
blen = ntail;
}
}
/* avoid strcasecompare because the host name is not null terminated */
if((hlen == ntail) && strncasecompare(hostname, sts->host, hlen))
return sts;
}
}
return bestsub;
}
/*
* Send this HSTS entry to the write callback.
*/
static CURLcode hsts_push(struct Curl_easy *data,
struct curl_index *i,
struct stsentry *sts,
bool *stop)
{
struct curl_hstsentry e;
CURLSTScode sc;
struct tm stamp;
CURLcode result;
e.name = (char *)sts->host;
e.namelen = strlen(sts->host);
e.includeSubDomains = sts->includeSubDomains;
if(sts->expires != TIME_T_MAX) {
result = Curl_gmtime((time_t)sts->expires, &stamp);
if(result)
return result;
msnprintf(e.expire, sizeof(e.expire), "%d%02d%02d %02d:%02d:%02d",
stamp.tm_year + 1900, stamp.tm_mon + 1, stamp.tm_mday,
stamp.tm_hour, stamp.tm_min, stamp.tm_sec);
}
else
strcpy(e.expire, UNLIMITED);
sc = data->set.hsts_write(data, &e, i,
data->set.hsts_write_userp);
*stop = (sc != CURLSTS_OK);
return sc == CURLSTS_FAIL ? CURLE_BAD_FUNCTION_ARGUMENT : CURLE_OK;
}
/*
* Write this single hsts entry to a single output line
*/
static CURLcode hsts_out(struct stsentry *sts, FILE *fp)
{
struct tm stamp;
if(sts->expires != TIME_T_MAX) {
CURLcode result = Curl_gmtime((time_t)sts->expires, &stamp);
if(result)
return result;
fprintf(fp, "%s%s \"%d%02d%02d %02d:%02d:%02d\"\n",
sts->includeSubDomains ? ".": "", sts->host,
stamp.tm_year + 1900, stamp.tm_mon + 1, stamp.tm_mday,
stamp.tm_hour, stamp.tm_min, stamp.tm_sec);
}
else
fprintf(fp, "%s%s \"%s\"\n",
sts->includeSubDomains ? ".": "", sts->host, UNLIMITED);
return CURLE_OK;
}
/*
* Curl_https_save() writes the HSTS cache to file and callback.
*/
CURLcode Curl_hsts_save(struct Curl_easy *data, struct hsts *h,
const char *file)
{
struct Curl_llist_node *e;
struct Curl_llist_node *n;
CURLcode result = CURLE_OK;
FILE *out;
char *tempstore = NULL;
if(!h)
/* no cache activated */
return CURLE_OK;
/* if no new name is given, use the one we stored from the load */
if(!file && h->filename)
file = h->filename;
if((h->flags & CURLHSTS_READONLYFILE) || !file || !file[0])
/* marked as read-only, no file or zero length filename */
goto skipsave;
result = Curl_fopen(data, file, &out, &tempstore);
if(!result) {
fputs("# Your HSTS cache. https://curl.se/docs/hsts.html\n"
"# This file was generated by libcurl! Edit at your own risk.\n",
out);
for(e = Curl_llist_head(&h->list); e; e = n) {
struct stsentry *sts = Curl_node_elem(e);
n = Curl_node_next(e);
result = hsts_out(sts, out);
if(result)
break;
}
fclose(out);
if(!result && tempstore && Curl_rename(tempstore, file))
result = CURLE_WRITE_ERROR;
if(result && tempstore)
unlink(tempstore);
}
free(tempstore);
skipsave:
if(data->set.hsts_write) {
/* if there is a write callback */
struct curl_index i; /* count */
i.total = Curl_llist_count(&h->list);
i.index = 0;
for(e = Curl_llist_head(&h->list); e; e = n) {
struct stsentry *sts = Curl_node_elem(e);
bool stop;
n = Curl_node_next(e);
result = hsts_push(data, &i, sts, &stop);
if(result || stop)
break;
i.index++;
}
}
return result;
}
/* only returns SERIOUS errors */
static CURLcode hsts_add(struct hsts *h, const char *line)
{
/* Example lines:
example.com "20191231 10:00:00"
.example.net "20191231 10:00:00"
*/
struct Curl_str host;
struct Curl_str date;
if(Curl_str_word(&line, &host, MAX_HSTS_HOSTLEN) ||
Curl_str_singlespace(&line) ||
Curl_str_quotedword(&line, &date, MAX_HSTS_DATELEN) ||
Curl_str_newline(&line))
;
else {
CURLcode result = CURLE_OK;
bool subdomain = FALSE;
struct stsentry *e;
char dbuf[MAX_HSTS_DATELEN + 1];
time_t expires;
const char *hp = Curl_str(&host);
/* The date parser works on a null terminated string. The maximum length
is upheld by Curl_str_quotedword(). */
memcpy(dbuf, Curl_str(&date), Curl_strlen(&date));
dbuf[Curl_strlen(&date)] = 0;
expires = strcmp(dbuf, UNLIMITED) ? Curl_getdate_capped(dbuf) :
TIME_T_MAX;
if(hp[0] == '.') {
Curl_str_nudge(&host, 1);
subdomain = TRUE;
}
/* only add it if not already present */
e = Curl_hsts(h, Curl_str(&host), Curl_strlen(&host), subdomain);
if(!e)
result = hsts_create(h, Curl_str(&host), Curl_strlen(&host),
subdomain, expires);
else if(Curl_str_casecompare(&host, e->host)) {
/* the same hostname, use the largest expire time */
if(expires > e->expires)
e->expires = expires;
}
if(result)
return result;
}
return CURLE_OK;
}
/*
* Load HSTS data from callback.
*
*/
static CURLcode hsts_pull(struct Curl_easy *data, struct hsts *h)
{
/* if the HSTS read callback is set, use it */
if(data->set.hsts_read) {
CURLSTScode sc;
DEBUGASSERT(h);
do {
char buffer[MAX_HSTS_HOSTLEN + 1];
struct curl_hstsentry e;
e.name = buffer;
e.namelen = sizeof(buffer)-1;
e.includeSubDomains = FALSE; /* default */
e.expire[0] = 0;
e.name[0] = 0; /* just to make it clean */
sc = data->set.hsts_read(data, &e, data->set.hsts_read_userp);
if(sc == CURLSTS_OK) {
time_t expires;
CURLcode result;
DEBUGASSERT(e.name[0]);
if(!e.name[0])
/* bail out if no name was stored */
return CURLE_BAD_FUNCTION_ARGUMENT;
if(e.expire[0])
expires = Curl_getdate_capped(e.expire);
else
expires = TIME_T_MAX; /* the end of time */
result = hsts_create(h, e.name, strlen(e.name),
/* bitfield to bool conversion: */
e.includeSubDomains ? TRUE : FALSE,
expires);
if(result)
return result;
}
else if(sc == CURLSTS_FAIL)
return CURLE_ABORTED_BY_CALLBACK;
} while(sc == CURLSTS_OK);
}
return CURLE_OK;
}
/*
* Load the HSTS cache from the given file. The text based line-oriented file
* format is documented here: https://curl.se/docs/hsts.html
*
* This function only returns error on major problems that prevent hsts
* handling to work completely. It will ignore individual syntactical errors
* etc.
*/
static CURLcode hsts_load(struct hsts *h, const char *file)
{
CURLcode result = CURLE_OK;
FILE *fp;
/* we need a private copy of the filename so that the hsts cache file
name survives an easy handle reset */
free(h->filename);
h->filename = strdup(file);
if(!h->filename)
return CURLE_OUT_OF_MEMORY;
fp = fopen(file, FOPEN_READTEXT);
if(fp) {
struct dynbuf buf;
Curl_dyn_init(&buf, MAX_HSTS_LINE);
while(Curl_get_line(&buf, fp)) {
char *lineptr = Curl_dyn_ptr(&buf);
while(ISBLANK(*lineptr))
lineptr++;
/*
* Skip empty or commented lines, since we know the line will have a
* trailing newline from Curl_get_line we can treat length 1 as empty.
*/
if((*lineptr == '#') || strlen(lineptr) <= 1)
continue;
hsts_add(h, lineptr);
}
Curl_dyn_free(&buf); /* free the line buffer */
fclose(fp);
}
return result;
}
/*
* Curl_hsts_loadfile() loads HSTS from file
*/
CURLcode Curl_hsts_loadfile(struct Curl_easy *data,
struct hsts *h, const char *file)
{
DEBUGASSERT(h);
(void)data;
return hsts_load(h, file);
}
/*
* Curl_hsts_loadcb() loads HSTS from callback
*/
CURLcode Curl_hsts_loadcb(struct Curl_easy *data, struct hsts *h)
{
if(h)
return hsts_pull(data, h);
return CURLE_OK;
}
void Curl_hsts_loadfiles(struct Curl_easy *data)
{
struct curl_slist *l = data->state.hstslist;
if(l) {
Curl_share_lock(data, CURL_LOCK_DATA_HSTS, CURL_LOCK_ACCESS_SINGLE);
while(l) {
(void)Curl_hsts_loadfile(data, data->hsts, l->data);
l = l->next;
}
Curl_share_unlock(data, CURL_LOCK_DATA_HSTS);
}
}
#endif /* CURL_DISABLE_HTTP || CURL_DISABLE_HSTS */
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