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9a0cf56471
curl/lib/doh.c
Stefan Eissing 5a9262a333
url: dns_entry related improvements 
Replace Curl_resolv_unlock() with Curl_resolv_unlink():

-replace inuse member with refcount in Curl_dns_entry

- pass Curl_dns_entry ** to unlink, so it gets always cleared

- solve potential (but unlikley) UAF in FTP's handling of looked up
  Curl_dns_entry. Esp. do not use addr information after unlinking an entry.
  In reality, the unlink will not free memory, as the dns entry is still
  referenced by the hostcache. But this is not safe and relying on no other
  code pruning the cache in the meantime.

- pass permanent flag when adding a dns entry instead of fixing timestamp
  afterwards.

url.c: fold several static *resolve_* functions into one.

Closes #14195
2024-08-03 19:51:02 +02:00

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/***************************************************************************
* _ _ ____ _
* 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
*
***************************************************************************/
#include "curl_setup.h"
#ifndef CURL_DISABLE_DOH
#include "urldata.h"
#include "curl_addrinfo.h"
#include "doh.h"
#include "sendf.h"
#include "multiif.h"
#include "url.h"
#include "share.h"
#include "curl_base64.h"
#include "connect.h"
#include "strdup.h"
#include "dynbuf.h"
/* The last 3 #include files should be in this order */
#include "curl_printf.h"
#include "curl_memory.h"
#include "memdebug.h"
#include "escape.h"
#define DNS_CLASS_IN 0x01
/* local_print_buf truncates if the hex string will be more than this */
#define LOCAL_PB_HEXMAX 400
#ifndef CURL_DISABLE_VERBOSE_STRINGS
static const char * const errors[]={
"",
"Bad label",
"Out of range",
"Label loop",
"Too small",
"Out of memory",
"RDATA length",
"Malformat",
"Bad RCODE",
"Unexpected TYPE",
"Unexpected CLASS",
"No content",
"Bad ID",
"Name too long"
};
static const char *doh_strerror(DOHcode code)
{
if((code >= DOH_OK) && (code <= DOH_DNS_NAME_TOO_LONG))
return errors[code];
return "bad error code";
}
struct curl_trc_feat Curl_doh_trc = {
"DoH",
CURL_LOG_LVL_NONE,
};
#endif /* !CURL_DISABLE_VERBOSE_STRINGS */
/* @unittest 1655
*/
UNITTEST DOHcode doh_encode(const char *host,
DNStype dnstype,
unsigned char *dnsp, /* buffer */
size_t len, /* buffer size */
size_t *olen) /* output length */
{
const size_t hostlen = strlen(host);
unsigned char *orig = dnsp;
const char *hostp = host;
/* The expected output length is 16 bytes more than the length of
* the QNAME-encoding of the hostname.
*
* A valid DNS name may not contain a zero-length label, except at
* the end. For this reason, a name beginning with a dot, or
* containing a sequence of two or more consecutive dots, is invalid
* and cannot be encoded as a QNAME.
*
* If the hostname ends with a trailing dot, the corresponding
* QNAME-encoding is one byte longer than the hostname. If (as is
* also valid) the hostname is shortened by the omission of the
* trailing dot, then its QNAME-encoding will be two bytes longer
* than the hostname.
*
* Each [ label, dot ] pair is encoded as [ length, label ],
* preserving overall length. A final [ label ] without a dot is
* also encoded as [ length, label ], increasing overall length
* by one. The encoding is completed by appending a zero byte,
* representing the zero-length root label, again increasing
* the overall length by one.
*/
size_t expected_len;
DEBUGASSERT(hostlen);
expected_len = 12 + 1 + hostlen + 4;
if(host[hostlen-1]!='.')
expected_len++;
if(expected_len > (256 + 16)) /* RFCs 1034, 1035 */
return DOH_DNS_NAME_TOO_LONG;
if(len < expected_len)
return DOH_TOO_SMALL_BUFFER;
*dnsp++ = 0; /* 16 bit id */
*dnsp++ = 0;
*dnsp++ = 0x01; /* |QR| Opcode |AA|TC|RD| Set the RD bit */
*dnsp++ = '\0'; /* |RA| Z | RCODE | */
*dnsp++ = '\0';
*dnsp++ = 1; /* QDCOUNT (number of entries in the question section) */
*dnsp++ = '\0';
*dnsp++ = '\0'; /* ANCOUNT */
*dnsp++ = '\0';
*dnsp++ = '\0'; /* NSCOUNT */
*dnsp++ = '\0';
*dnsp++ = '\0'; /* ARCOUNT */
/* encode each label and store it in the QNAME */
while(*hostp) {
size_t labellen;
char *dot = strchr(hostp, '.');
if(dot)
labellen = dot - hostp;
else
labellen = strlen(hostp);
if((labellen > 63) || (!labellen)) {
/* label is too long or too short, error out */
*olen = 0;
return DOH_DNS_BAD_LABEL;
}
/* label is non-empty, process it */
*dnsp++ = (unsigned char)labellen;
memcpy(dnsp, hostp, labellen);
dnsp += labellen;
hostp += labellen;
/* advance past dot, but only if there is one */
if(dot)
hostp++;
} /* next label */
*dnsp++ = 0; /* append zero-length label for root */
/* There are assigned TYPE codes beyond 255: use range [1..65535] */
*dnsp++ = (unsigned char)(255 & (dnstype>>8)); /* upper 8 bit TYPE */
*dnsp++ = (unsigned char)(255 & dnstype); /* lower 8 bit TYPE */
*dnsp++ = '\0'; /* upper 8 bit CLASS */
*dnsp++ = DNS_CLASS_IN; /* IN - "the Internet" */
*olen = dnsp - orig;
/* verify that our estimation of length is valid, since
* this has led to buffer overflows in this function */
DEBUGASSERT(*olen == expected_len);
return DOH_OK;
}
static size_t
doh_write_cb(const void *contents, size_t size, size_t nmemb, void *userp)
{
size_t realsize = size * nmemb;
struct dynbuf *mem = (struct dynbuf *)userp;
if(Curl_dyn_addn(mem, contents, realsize))
return 0;
return realsize;
}
#if defined(USE_HTTPSRR) && defined(DEBUGBUILD)
static void local_print_buf(struct Curl_easy *data,
const char *prefix,
unsigned char *buf, size_t len)
{
unsigned char hexstr[LOCAL_PB_HEXMAX];
size_t hlen = LOCAL_PB_HEXMAX;
bool truncated = false;
if(len > (LOCAL_PB_HEXMAX / 2))
truncated = true;
Curl_hexencode(buf, len, hexstr, hlen);
if(!truncated)
infof(data, "%s: len=%d, val=%s", prefix, (int)len, hexstr);
else
infof(data, "%s: len=%d (truncated)val=%s", prefix, (int)len, hexstr);
return;
}
#endif
/* called from multi.c when this DoH transfer is complete */
static int doh_done(struct Curl_easy *doh, CURLcode result)
{
struct Curl_easy *data = doh->set.dohfor;
struct dohdata *dohp = data->req.doh;
/* so one of the DoH request done for the 'data' transfer is now complete! */
dohp->pending--;
infof(doh, "a DoH request is completed, %u to go", dohp->pending);
if(result)
infof(doh, "DoH request %s", curl_easy_strerror(result));
if(!dohp->pending) {
/* DoH completed */
curl_slist_free_all(dohp->headers);
dohp->headers = NULL;
Curl_expire(data, 0, EXPIRE_RUN_NOW);
}
return 0;
}
#define ERROR_CHECK_SETOPT(x,y) \
do { \
result = curl_easy_setopt(doh, x, y); \
if(result && \
result != CURLE_NOT_BUILT_IN && \
result != CURLE_UNKNOWN_OPTION) \
goto error; \
} while(0)
static CURLcode dohprobe(struct Curl_easy *data,
struct dnsprobe *p, DNStype dnstype,
const char *host,
const char *url, CURLM *multi,
struct curl_slist *headers)
{
struct Curl_easy *doh = NULL;
CURLcode result = CURLE_OK;
timediff_t timeout_ms;
DOHcode d = doh_encode(host, dnstype, p->dohbuffer, sizeof(p->dohbuffer),
&p->dohlen);
if(d) {
failf(data, "Failed to encode DoH packet [%d]", d);
return CURLE_OUT_OF_MEMORY;
}
p->dnstype = dnstype;
Curl_dyn_init(&p->serverdoh, DYN_DOH_RESPONSE);
timeout_ms = Curl_timeleft(data, NULL, TRUE);
if(timeout_ms <= 0) {
result = CURLE_OPERATION_TIMEDOUT;
goto error;
}
/* Curl_open() is the internal version of curl_easy_init() */
result = Curl_open(&doh);
if(!result) {
/* pass in the struct pointer via a local variable to please coverity and
the gcc typecheck helpers */
struct dynbuf *resp = &p->serverdoh;
doh->state.internal = true;
#ifndef CURL_DISABLE_VERBOSE_STRINGS
doh->state.feat = &Curl_doh_trc;
#endif
ERROR_CHECK_SETOPT(CURLOPT_URL, url);
ERROR_CHECK_SETOPT(CURLOPT_DEFAULT_PROTOCOL, "https");
ERROR_CHECK_SETOPT(CURLOPT_WRITEFUNCTION, doh_write_cb);
ERROR_CHECK_SETOPT(CURLOPT_WRITEDATA, resp);
ERROR_CHECK_SETOPT(CURLOPT_POSTFIELDS, p->dohbuffer);
ERROR_CHECK_SETOPT(CURLOPT_POSTFIELDSIZE, (long)p->dohlen);
ERROR_CHECK_SETOPT(CURLOPT_HTTPHEADER, headers);
#ifdef USE_HTTP2
ERROR_CHECK_SETOPT(CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_2TLS);
ERROR_CHECK_SETOPT(CURLOPT_PIPEWAIT, 1L);
#endif
#ifndef DEBUGBUILD
/* enforce HTTPS if not debug */
ERROR_CHECK_SETOPT(CURLOPT_PROTOCOLS, CURLPROTO_HTTPS);
#else
/* in debug mode, also allow http */
ERROR_CHECK_SETOPT(CURLOPT_PROTOCOLS, CURLPROTO_HTTP|CURLPROTO_HTTPS);
#endif
ERROR_CHECK_SETOPT(CURLOPT_TIMEOUT_MS, (long)timeout_ms);
ERROR_CHECK_SETOPT(CURLOPT_SHARE, data->share);
if(data->set.err && data->set.err != stderr)
ERROR_CHECK_SETOPT(CURLOPT_STDERR, data->set.err);
if(Curl_trc_ft_is_verbose(data, &Curl_doh_trc))
ERROR_CHECK_SETOPT(CURLOPT_VERBOSE, 1L);
if(data->set.no_signal)
ERROR_CHECK_SETOPT(CURLOPT_NOSIGNAL, 1L);
ERROR_CHECK_SETOPT(CURLOPT_SSL_VERIFYHOST,
data->set.doh_verifyhost ? 2L : 0L);
ERROR_CHECK_SETOPT(CURLOPT_SSL_VERIFYPEER,
data->set.doh_verifypeer ? 1L : 0L);
ERROR_CHECK_SETOPT(CURLOPT_SSL_VERIFYSTATUS,
data->set.doh_verifystatus ? 1L : 0L);
/* Inherit *some* SSL options from the user's transfer. This is a
best-guess as to which options are needed for compatibility. #3661
Note DoH does not inherit the user's proxy server so proxy SSL settings
have no effect and are not inherited. If that changes then two new
options should be added to check doh proxy insecure separately,
CURLOPT_DOH_PROXY_SSL_VERIFYHOST and CURLOPT_DOH_PROXY_SSL_VERIFYPEER.
*/
if(data->set.ssl.falsestart)
ERROR_CHECK_SETOPT(CURLOPT_SSL_FALSESTART, 1L);
if(data->set.str[STRING_SSL_CAFILE]) {
ERROR_CHECK_SETOPT(CURLOPT_CAINFO,
data->set.str[STRING_SSL_CAFILE]);
}
if(data->set.blobs[BLOB_CAINFO]) {
ERROR_CHECK_SETOPT(CURLOPT_CAINFO_BLOB,
data->set.blobs[BLOB_CAINFO]);
}
if(data->set.str[STRING_SSL_CAPATH]) {
ERROR_CHECK_SETOPT(CURLOPT_CAPATH,
data->set.str[STRING_SSL_CAPATH]);
}
if(data->set.str[STRING_SSL_CRLFILE]) {
ERROR_CHECK_SETOPT(CURLOPT_CRLFILE,
data->set.str[STRING_SSL_CRLFILE]);
}
if(data->set.ssl.certinfo)
ERROR_CHECK_SETOPT(CURLOPT_CERTINFO, 1L);
if(data->set.ssl.fsslctx)
ERROR_CHECK_SETOPT(CURLOPT_SSL_CTX_FUNCTION, data->set.ssl.fsslctx);
if(data->set.ssl.fsslctxp)
ERROR_CHECK_SETOPT(CURLOPT_SSL_CTX_DATA, data->set.ssl.fsslctxp);
if(data->set.fdebug)
ERROR_CHECK_SETOPT(CURLOPT_DEBUGFUNCTION, data->set.fdebug);
if(data->set.debugdata)
ERROR_CHECK_SETOPT(CURLOPT_DEBUGDATA, data->set.debugdata);
if(data->set.str[STRING_SSL_EC_CURVES]) {
ERROR_CHECK_SETOPT(CURLOPT_SSL_EC_CURVES,
data->set.str[STRING_SSL_EC_CURVES]);
}
{
long mask =
(data->set.ssl.enable_beast ?
CURLSSLOPT_ALLOW_BEAST : 0) |
(data->set.ssl.no_revoke ?
CURLSSLOPT_NO_REVOKE : 0) |
(data->set.ssl.no_partialchain ?
CURLSSLOPT_NO_PARTIALCHAIN : 0) |
(data->set.ssl.revoke_best_effort ?
CURLSSLOPT_REVOKE_BEST_EFFORT : 0) |
(data->set.ssl.native_ca_store ?
CURLSSLOPT_NATIVE_CA : 0) |
(data->set.ssl.auto_client_cert ?
CURLSSLOPT_AUTO_CLIENT_CERT : 0);
(void)curl_easy_setopt(doh, CURLOPT_SSL_OPTIONS, mask);
}
doh->set.fmultidone = doh_done;
doh->set.dohfor = data; /* identify for which transfer this is done */
p->easy = doh;
/* DoH handles must not inherit private_data. The handles may be passed to
the user via callbacks and the user will be able to identify them as
internal handles because private data is not set. The user can then set
private_data via CURLOPT_PRIVATE if they so choose. */
DEBUGASSERT(!doh->set.private_data);
if(curl_multi_add_handle(multi, doh))
goto error;
}
else
goto error;
return CURLE_OK;
error:
Curl_close(&doh);
return result;
}
/*
* Curl_doh() resolves a name using DoH. It resolves a name and returns a
* 'Curl_addrinfo *' with the address information.
*/
struct Curl_addrinfo *Curl_doh(struct Curl_easy *data,
const char *hostname,
int port,
int *waitp)
{
CURLcode result = CURLE_OK;
struct dohdata *dohp;
struct connectdata *conn = data->conn;
#ifdef USE_HTTPSRR
/* for now, this is only used when ECH is enabled */
# ifdef USE_ECH
char *qname = NULL;
# endif
#endif
*waitp = FALSE;
(void)hostname;
(void)port;
DEBUGASSERT(!data->req.doh);
DEBUGASSERT(conn);
/* start clean, consider allocating this struct on demand */
dohp = data->req.doh = calloc(1, sizeof(struct dohdata));
if(!dohp)
return NULL;
conn->bits.doh = TRUE;
dohp->host = hostname;
dohp->port = port;
dohp->headers =
curl_slist_append(NULL,
"Content-Type: application/dns-message");
if(!dohp->headers)
goto error;
/* create IPv4 DoH request */
result = dohprobe(data, &dohp->probe[DOH_PROBE_SLOT_IPADDR_V4],
DNS_TYPE_A, hostname, data->set.str[STRING_DOH],
data->multi, dohp->headers);
if(result)
goto error;
dohp->pending++;
#ifdef USE_IPV6
if((conn->ip_version != CURL_IPRESOLVE_V4) && Curl_ipv6works(data)) {
/* create IPv6 DoH request */
result = dohprobe(data, &dohp->probe[DOH_PROBE_SLOT_IPADDR_V6],
DNS_TYPE_AAAA, hostname, data->set.str[STRING_DOH],
data->multi, dohp->headers);
if(result)
goto error;
dohp->pending++;
}
#endif
#ifdef USE_HTTPSRR
/*
* TODO: Figure out the conditions under which we want to make
* a request for an HTTPS RR when we are not doing ECH. For now,
* making this request breaks a bunch of DoH tests, e.g. test2100,
* where the additional request does not match the pre-cooked data
* files, so there is a bit of work attached to making the request
* in a non-ECH use-case. For the present, we will only make the
* request when ECH is enabled in the build and is being used for
* the curl operation.
*/
# ifdef USE_ECH
if(data->set.tls_ech & CURLECH_ENABLE
|| data->set.tls_ech & CURLECH_HARD) {
if(port == 443)
qname = strdup(hostname);
else
qname = aprintf("_%d._https.%s", port, hostname);
if(!qname)
goto error;
result = dohprobe(data, &dohp->probe[DOH_PROBE_SLOT_HTTPS],
DNS_TYPE_HTTPS, qname, data->set.str[STRING_DOH],
data->multi, dohp->headers);
Curl_safefree(qname);
if(result)
goto error;
dohp->pending++;
}
# endif
#endif
*waitp = TRUE; /* this never returns synchronously */
return NULL;
error:
Curl_doh_cleanup(data);
return NULL;
}
static DOHcode skipqname(const unsigned char *doh, size_t dohlen,
unsigned int *indexp)
{
unsigned char length;
do {
if(dohlen < (*indexp + 1))
return DOH_DNS_OUT_OF_RANGE;
length = doh[*indexp];
if((length & 0xc0) == 0xc0) {
/* name pointer, advance over it and be done */
if(dohlen < (*indexp + 2))
return DOH_DNS_OUT_OF_RANGE;
*indexp += 2;
break;
}
if(length & 0xc0)
return DOH_DNS_BAD_LABEL;
if(dohlen < (*indexp + 1 + length))
return DOH_DNS_OUT_OF_RANGE;
*indexp += (unsigned int)(1 + length);
} while(length);
return DOH_OK;
}
static unsigned short get16bit(const unsigned char *doh, unsigned int index)
{
return (unsigned short)((doh[index] << 8) | doh[index + 1]);
}
static unsigned int get32bit(const unsigned char *doh, unsigned int index)
{
/* make clang and gcc optimize this to bswap by incrementing
the pointer first. */
doh += index;
/* avoid undefined behavior by casting to unsigned before shifting
24 bits, possibly into the sign bit. codegen is same, but
ub sanitizer will not be upset */
return ((unsigned)doh[0] << 24) | ((unsigned)doh[1] << 16) |
((unsigned)doh[2] << 8) | doh[3];
}
static DOHcode store_a(const unsigned char *doh, int index, struct dohentry *d)
{
/* silently ignore addresses over the limit */
if(d->numaddr < DOH_MAX_ADDR) {
struct dohaddr *a = &d->addr[d->numaddr];
a->type = DNS_TYPE_A;
memcpy(&a->ip.v4, &doh[index], 4);
d->numaddr++;
}
return DOH_OK;
}
static DOHcode store_aaaa(const unsigned char *doh,
int index,
struct dohentry *d)
{
/* silently ignore addresses over the limit */
if(d->numaddr < DOH_MAX_ADDR) {
struct dohaddr *a = &d->addr[d->numaddr];
a->type = DNS_TYPE_AAAA;
memcpy(&a->ip.v6, &doh[index], 16);
d->numaddr++;
}
return DOH_OK;
}
#ifdef USE_HTTPSRR
static DOHcode store_https(const unsigned char *doh,
int index,
struct dohentry *d,
uint16_t len)
{
/* silently ignore RRs over the limit */
if(d->numhttps_rrs < DOH_MAX_HTTPS) {
struct dohhttps_rr *h = &d->https_rrs[d->numhttps_rrs];
h->val = Curl_memdup(&doh[index], len);
if(!h->val)
return DOH_OUT_OF_MEM;
h->len = len;
d->numhttps_rrs++;
}
return DOH_OK;
}
#endif
static DOHcode store_cname(const unsigned char *doh,
size_t dohlen,
unsigned int index,
struct dohentry *d)
{
struct dynbuf *c;
unsigned int loop = 128; /* a valid DNS name can never loop this much */
unsigned char length;
if(d->numcname == DOH_MAX_CNAME)
return DOH_OK; /* skip! */
c = &d->cname[d->numcname++];
do {
if(index >= dohlen)
return DOH_DNS_OUT_OF_RANGE;
length = doh[index];
if((length & 0xc0) == 0xc0) {
int newpos;
/* name pointer, get the new offset (14 bits) */
if((index + 1) >= dohlen)
return DOH_DNS_OUT_OF_RANGE;
/* move to the new index */
newpos = (length & 0x3f) << 8 | doh[index + 1];
index = (unsigned int)newpos;
continue;
}
else if(length & 0xc0)
return DOH_DNS_BAD_LABEL; /* bad input */
else
index++;
if(length) {
if(Curl_dyn_len(c)) {
if(Curl_dyn_addn(c, STRCONST(".")))
return DOH_OUT_OF_MEM;
}
if((index + length) > dohlen)
return DOH_DNS_BAD_LABEL;
if(Curl_dyn_addn(c, &doh[index], length))
return DOH_OUT_OF_MEM;
index += length;
}
} while(length && --loop);
if(!loop)
return DOH_DNS_LABEL_LOOP;
return DOH_OK;
}
static DOHcode rdata(const unsigned char *doh,
size_t dohlen,
unsigned short rdlength,
unsigned short type,
int index,
struct dohentry *d)
{
/* RDATA
- A (TYPE 1): 4 bytes
- AAAA (TYPE 28): 16 bytes
- NS (TYPE 2): N bytes
- HTTPS (TYPE 65): N bytes */
DOHcode rc;
switch(type) {
case DNS_TYPE_A:
if(rdlength != 4)
return DOH_DNS_RDATA_LEN;
rc = store_a(doh, index, d);
if(rc)
return rc;
break;
case DNS_TYPE_AAAA:
if(rdlength != 16)
return DOH_DNS_RDATA_LEN;
rc = store_aaaa(doh, index, d);
if(rc)
return rc;
break;
#ifdef USE_HTTPSRR
case DNS_TYPE_HTTPS:
rc = store_https(doh, index, d, rdlength);
if(rc)
return rc;
break;
#endif
case DNS_TYPE_CNAME:
rc = store_cname(doh, dohlen, (unsigned int)index, d);
if(rc)
return rc;
break;
case DNS_TYPE_DNAME:
/* explicit for clarity; just skip; rely on synthesized CNAME */
break;
default:
/* unsupported type, just skip it */
break;
}
return DOH_OK;
}
UNITTEST void de_init(struct dohentry *de)
{
int i;
memset(de, 0, sizeof(*de));
de->ttl = INT_MAX;
for(i = 0; i < DOH_MAX_CNAME; i++)
Curl_dyn_init(&de->cname[i], DYN_DOH_CNAME);
}
UNITTEST DOHcode doh_decode(const unsigned char *doh,
size_t dohlen,
DNStype dnstype,
struct dohentry *d)
{
unsigned char rcode;
unsigned short qdcount;
unsigned short ancount;
unsigned short type = 0;
unsigned short rdlength;
unsigned short nscount;
unsigned short arcount;
unsigned int index = 12;
DOHcode rc;
if(dohlen < 12)
return DOH_TOO_SMALL_BUFFER; /* too small */
if(!doh || doh[0] || doh[1])
return DOH_DNS_BAD_ID; /* bad ID */
rcode = doh[3] & 0x0f;
if(rcode)
return DOH_DNS_BAD_RCODE; /* bad rcode */
qdcount = get16bit(doh, 4);
while(qdcount) {
rc = skipqname(doh, dohlen, &index);
if(rc)
return rc; /* bad qname */
if(dohlen < (index + 4))
return DOH_DNS_OUT_OF_RANGE;
index += 4; /* skip question's type and class */
qdcount--;
}
ancount = get16bit(doh, 6);
while(ancount) {
unsigned short class;
unsigned int ttl;
rc = skipqname(doh, dohlen, &index);
if(rc)
return rc; /* bad qname */
if(dohlen < (index + 2))
return DOH_DNS_OUT_OF_RANGE;
type = get16bit(doh, index);
if((type != DNS_TYPE_CNAME) /* may be synthesized from DNAME */
&& (type != DNS_TYPE_DNAME) /* if present, accept and ignore */
&& (type != dnstype))
/* Not the same type as was asked for nor CNAME nor DNAME */
return DOH_DNS_UNEXPECTED_TYPE;
index += 2;
if(dohlen < (index + 2))
return DOH_DNS_OUT_OF_RANGE;
class = get16bit(doh, index);
if(DNS_CLASS_IN != class)
return DOH_DNS_UNEXPECTED_CLASS; /* unsupported */
index += 2;
if(dohlen < (index + 4))
return DOH_DNS_OUT_OF_RANGE;
ttl = get32bit(doh, index);
if(ttl < d->ttl)
d->ttl = ttl;
index += 4;
if(dohlen < (index + 2))
return DOH_DNS_OUT_OF_RANGE;
rdlength = get16bit(doh, index);
index += 2;
if(dohlen < (index + rdlength))
return DOH_DNS_OUT_OF_RANGE;
rc = rdata(doh, dohlen, rdlength, type, (int)index, d);
if(rc)
return rc; /* bad rdata */
index += rdlength;
ancount--;
}
nscount = get16bit(doh, 8);
while(nscount) {
rc = skipqname(doh, dohlen, &index);
if(rc)
return rc; /* bad qname */
if(dohlen < (index + 8))
return DOH_DNS_OUT_OF_RANGE;
index += 2 + 2 + 4; /* type, class and ttl */
if(dohlen < (index + 2))
return DOH_DNS_OUT_OF_RANGE;
rdlength = get16bit(doh, index);
index += 2;
if(dohlen < (index + rdlength))
return DOH_DNS_OUT_OF_RANGE;
index += rdlength;
nscount--;
}
arcount = get16bit(doh, 10);
while(arcount) {
rc = skipqname(doh, dohlen, &index);
if(rc)
return rc; /* bad qname */
if(dohlen < (index + 8))
return DOH_DNS_OUT_OF_RANGE;
index += 2 + 2 + 4; /* type, class and ttl */
if(dohlen < (index + 2))
return DOH_DNS_OUT_OF_RANGE;
rdlength = get16bit(doh, index);
index += 2;
if(dohlen < (index + rdlength))
return DOH_DNS_OUT_OF_RANGE;
index += rdlength;
arcount--;
}
if(index != dohlen)
return DOH_DNS_MALFORMAT; /* something is wrong */
#ifdef USE_HTTTPS
if((type != DNS_TYPE_NS) && !d->numcname && !d->numaddr && !d->numhttps_rrs)
#else
if((type != DNS_TYPE_NS) && !d->numcname && !d->numaddr)
#endif
/* nothing stored! */
return DOH_NO_CONTENT;
return DOH_OK; /* ok */
}
#ifndef CURL_DISABLE_VERBOSE_STRINGS
static void showdoh(struct Curl_easy *data,
const struct dohentry *d)
{
int i;
infof(data, "[DoH] TTL: %u seconds", d->ttl);
for(i = 0; i < d->numaddr; i++) {
const struct dohaddr *a = &d->addr[i];
if(a->type == DNS_TYPE_A) {
infof(data, "[DoH] A: %u.%u.%u.%u",
a->ip.v4[0], a->ip.v4[1],
a->ip.v4[2], a->ip.v4[3]);
}
else if(a->type == DNS_TYPE_AAAA) {
int j;
char buffer[128];
char *ptr;
size_t len;
len = msnprintf(buffer, 128, "[DoH] AAAA: ");
ptr = &buffer[len];
len = sizeof(buffer) - len;
for(j = 0; j < 16; j += 2) {
size_t l;
msnprintf(ptr, len, "%s%02x%02x", j?":":"", d->addr[i].ip.v6[j],
d->addr[i].ip.v6[j + 1]);
l = strlen(ptr);
len -= l;
ptr += l;
}
infof(data, "%s", buffer);
}
}
#ifdef USE_HTTPSRR
for(i = 0; i < d->numhttps_rrs; i++) {
# ifdef DEBUGBUILD
local_print_buf(data, "DoH HTTPS",
d->https_rrs[i].val, d->https_rrs[i].len);
# else
infof(data, "DoH HTTPS RR: length %d", d->https_rrs[i].len);
# endif
}
#endif
for(i = 0; i < d->numcname; i++) {
infof(data, "CNAME: %s", Curl_dyn_ptr(&d->cname[i]));
}
}
#else
#define showdoh(x,y)
#endif
/*
* doh2ai()
*
* This function returns a pointer to the first element of a newly allocated
* Curl_addrinfo struct linked list filled with the data from a set of DoH
* lookups. Curl_addrinfo is meant to work like the addrinfo struct does for
* a IPv6 stack, but usable also for IPv4, all hosts and environments.
*
* The memory allocated by this function *MUST* be free'd later on calling
* Curl_freeaddrinfo(). For each successful call to this function there
* must be an associated call later to Curl_freeaddrinfo().
*/
static CURLcode doh2ai(const struct dohentry *de, const char *hostname,
int port, struct Curl_addrinfo **aip)
{
struct Curl_addrinfo *ai;
struct Curl_addrinfo *prevai = NULL;
struct Curl_addrinfo *firstai = NULL;
struct sockaddr_in *addr;
#ifdef USE_IPV6
struct sockaddr_in6 *addr6;
#endif
CURLcode result = CURLE_OK;
int i;
size_t hostlen = strlen(hostname) + 1; /* include null-terminator */
DEBUGASSERT(de);
if(!de->numaddr)
return CURLE_COULDNT_RESOLVE_HOST;
for(i = 0; i < de->numaddr; i++) {
size_t ss_size;
CURL_SA_FAMILY_T addrtype;
if(de->addr[i].type == DNS_TYPE_AAAA) {
#ifndef USE_IPV6
/* we cannot handle IPv6 addresses */
continue;
#else
ss_size = sizeof(struct sockaddr_in6);
addrtype = AF_INET6;
#endif
}
else {
ss_size = sizeof(struct sockaddr_in);
addrtype = AF_INET;
}
ai = calloc(1, sizeof(struct Curl_addrinfo) + ss_size + hostlen);
if(!ai) {
result = CURLE_OUT_OF_MEMORY;
break;
}
ai->ai_addr = (void *)((char *)ai + sizeof(struct Curl_addrinfo));
ai->ai_canonname = (void *)((char *)ai->ai_addr + ss_size);
memcpy(ai->ai_canonname, hostname, hostlen);
if(!firstai)
/* store the pointer we want to return from this function */
firstai = ai;
if(prevai)
/* make the previous entry point to this */
prevai->ai_next = ai;
ai->ai_family = addrtype;
/* we return all names as STREAM, so when using this address for TFTP
the type must be ignored and conn->socktype be used instead! */
ai->ai_socktype = SOCK_STREAM;
ai->ai_addrlen = (curl_socklen_t)ss_size;
/* leave the rest of the struct filled with zero */
switch(ai->ai_family) {
case AF_INET:
addr = (void *)ai->ai_addr; /* storage area for this info */
DEBUGASSERT(sizeof(struct in_addr) == sizeof(de->addr[i].ip.v4));
memcpy(&addr->sin_addr, &de->addr[i].ip.v4, sizeof(struct in_addr));
#ifdef __MINGW32__
addr->sin_family = (short)addrtype;
#else
addr->sin_family = addrtype;
#endif
addr->sin_port = htons((unsigned short)port);
break;
#ifdef USE_IPV6
case AF_INET6:
addr6 = (void *)ai->ai_addr; /* storage area for this info */
DEBUGASSERT(sizeof(struct in6_addr) == sizeof(de->addr[i].ip.v6));
memcpy(&addr6->sin6_addr, &de->addr[i].ip.v6, sizeof(struct in6_addr));
#ifdef __MINGW32__
addr6->sin6_family = (short)addrtype;
#else
addr6->sin6_family = addrtype;
#endif
addr6->sin6_port = htons((unsigned short)port);
break;
#endif
}
prevai = ai;
}
if(result) {
Curl_freeaddrinfo(firstai);
firstai = NULL;
}
*aip = firstai;
return result;
}
#ifndef CURL_DISABLE_VERBOSE_STRINGS
static const char *type2name(DNStype dnstype)
{
switch(dnstype) {
case DNS_TYPE_A:
return "A";
case DNS_TYPE_AAAA:
return "AAAA";
#ifdef USE_HTTPSRR
case DNS_TYPE_HTTPS:
return "HTTPS";
#endif
default:
return "unknown";
}
}
#endif
UNITTEST void de_cleanup(struct dohentry *d)
{
int i = 0;
for(i = 0; i < d->numcname; i++) {
Curl_dyn_free(&d->cname[i]);
}
#ifdef USE_HTTPSRR
for(i = 0; i < d->numhttps_rrs; i++)
Curl_safefree(d->https_rrs[i].val);
#endif
}
#ifdef USE_HTTPSRR
/*
* @brief decode the DNS name in a binary RRData
* @param buf points to the buffer (in/out)
* @param remaining points to the remaining buffer length (in/out)
* @param dnsname returns the string form name on success
* @return is 1 for success, error otherwise
*
* The encoding here is defined in
* https://tools.ietf.org/html/rfc1035#section-3.1
*
* The input buffer pointer will be modified so it points to
* just after the end of the DNS name encoding on output. (And
* that is why it is an "unsigned char **" :-)
*/
static CURLcode local_decode_rdata_name(unsigned char **buf, size_t *remaining,
char **dnsname)
{
unsigned char *cp = NULL;
int rem = 0;
unsigned char clen = 0; /* chunk len */
struct dynbuf thename;
DEBUGASSERT(buf && remaining && dnsname);
if(!buf || !remaining || !dnsname)
return CURLE_OUT_OF_MEMORY;
rem = (int)*remaining;
if(rem <= 0) {
Curl_dyn_free(&thename);
return CURLE_OUT_OF_MEMORY;
}
Curl_dyn_init(&thename, CURL_MAXLEN_host_name);
cp = *buf;
clen = *cp++;
if(clen == 0) {
/* special case - return "." as name */
if(Curl_dyn_addn(&thename, ".", 1))
return CURLE_OUT_OF_MEMORY;
}
while(clen) {
if(clen >= rem) {
Curl_dyn_free(&thename);
return CURLE_OUT_OF_MEMORY;
}
if(Curl_dyn_addn(&thename, cp, clen) ||
Curl_dyn_addn(&thename, ".", 1))
return CURLE_TOO_LARGE;
cp += clen;
rem -= (clen + 1);
if(rem <= 0) {
Curl_dyn_free(&thename);
return CURLE_OUT_OF_MEMORY;
}
clen = *cp++;
}
*buf = cp;
*remaining = rem - 1;
*dnsname = Curl_dyn_ptr(&thename);
return CURLE_OK;
}
static CURLcode local_decode_rdata_alpn(unsigned char *rrval, size_t len,
char **alpns)
{
/*
* spec here is as per draft-ietf-dnsop-svcb-https, section-7.1.1
* encoding is catenated list of strings each preceded by a one
* octet length
* output is comma-sep list of the strings
* implementations may or may not handle quoting of comma within
* string values, so we might see a comma within the wire format
* version of a string, in which case we will precede that by a
* backslash - same goes for a backslash character, and of course
* we need to use two backslashes in strings when we mean one;-)
*/
int remaining = (int) len;
char *oval;
size_t i;
unsigned char *cp = rrval;
struct dynbuf dval;
if(!alpns)
return CURLE_OUT_OF_MEMORY;
Curl_dyn_init(&dval, DYN_DOH_RESPONSE);
remaining = (int)len;
cp = rrval;
while(remaining > 0) {
size_t tlen = (size_t) *cp++;
/* if not 1st time, add comma */
if(remaining != (int)len && Curl_dyn_addn(&dval, ",", 1))
goto err;
remaining--;
if(tlen > (size_t)remaining)
goto err;
/* add escape char if needed, clunky but easier to read */
for(i = 0; i != tlen; i++) {
if('\\' == *cp || ',' == *cp) {
if(Curl_dyn_addn(&dval, "\\", 1))
goto err;
}
if(Curl_dyn_addn(&dval, cp++, 1))
goto err;
}
remaining -= (int)tlen;
}
/* this string is always null terminated */
oval = Curl_dyn_ptr(&dval);
if(!oval)
goto err;
*alpns = oval;
return CURLE_OK;
err:
Curl_dyn_free(&dval);
return CURLE_BAD_CONTENT_ENCODING;
}
#ifdef DEBUGBUILD
static CURLcode test_alpn_escapes(void)
{
/* we will use an example from draft-ietf-dnsop-svcb, figure 10 */
static unsigned char example[] = {
0x08, /* length 8 */
0x66, 0x5c, 0x6f, 0x6f, 0x2c, 0x62, 0x61, 0x72, /* value "f\\oo,bar" */
0x02, /* length 2 */
0x68, 0x32 /* value "h2" */
};
size_t example_len = sizeof(example);
char *aval = NULL;
static const char *expected = "f\\\\oo\\,bar,h2";
if(local_decode_rdata_alpn(example, example_len, &aval) != CURLE_OK)
return CURLE_BAD_CONTENT_ENCODING;
if(strlen(aval) != strlen(expected))
return CURLE_BAD_CONTENT_ENCODING;
if(memcmp(aval, expected, strlen(aval)))
return CURLE_BAD_CONTENT_ENCODING;
return CURLE_OK;
}
#endif
static CURLcode Curl_doh_decode_httpsrr(unsigned char *rrval, size_t len,
struct Curl_https_rrinfo **hrr)
{
size_t remaining = len;
unsigned char *cp = rrval;
uint16_t pcode = 0, plen = 0;
struct Curl_https_rrinfo *lhrr = NULL;
char *dnsname = NULL;
#ifdef DEBUGBUILD
/* a few tests of escaping, should not be here but ok for now */
if(test_alpn_escapes() != CURLE_OK)
return CURLE_OUT_OF_MEMORY;
#endif
lhrr = calloc(1, sizeof(struct Curl_https_rrinfo));
if(!lhrr)
return CURLE_OUT_OF_MEMORY;
lhrr->val = Curl_memdup(rrval, len);
if(!lhrr->val)
goto err;
lhrr->len = len;
if(remaining <= 2)
goto err;
lhrr->priority = (uint16_t)((cp[0] << 8) + cp[1]);
cp += 2;
remaining -= (uint16_t)2;
if(local_decode_rdata_name(&cp, &remaining, &dnsname) != CURLE_OK)
goto err;
lhrr->target = dnsname;
while(remaining >= 4) {
pcode = (uint16_t)((*cp << 8) + (*(cp + 1)));
cp += 2;
plen = (uint16_t)((*cp << 8) + (*(cp + 1)));
cp += 2;
remaining -= 4;
if(pcode == HTTPS_RR_CODE_ALPN) {
if(local_decode_rdata_alpn(cp, plen, &lhrr->alpns) != CURLE_OK)
goto err;
}
if(pcode == HTTPS_RR_CODE_NO_DEF_ALPN)
lhrr->no_def_alpn = TRUE;
else if(pcode == HTTPS_RR_CODE_IPV4) {
if(!plen)
goto err;
lhrr->ipv4hints = Curl_memdup(cp, plen);
if(!lhrr->ipv4hints)
goto err;
lhrr->ipv4hints_len = (size_t)plen;
}
else if(pcode == HTTPS_RR_CODE_ECH) {
if(!plen)
goto err;
lhrr->echconfiglist = Curl_memdup(cp, plen);
if(!lhrr->echconfiglist)
goto err;
lhrr->echconfiglist_len = (size_t)plen;
}
else if(pcode == HTTPS_RR_CODE_IPV6) {
if(!plen)
goto err;
lhrr->ipv6hints = Curl_memdup(cp, plen);
if(!lhrr->ipv6hints)
goto err;
lhrr->ipv6hints_len = (size_t)plen;
}
if(plen > 0 && plen <= remaining) {
cp += plen;
remaining -= plen;
}
}
DEBUGASSERT(!remaining);
*hrr = lhrr;
return CURLE_OK;
err:
if(lhrr) {
Curl_safefree(lhrr->target);
Curl_safefree(lhrr->echconfiglist);
Curl_safefree(lhrr->val);
Curl_safefree(lhrr->alpns);
Curl_safefree(lhrr);
}
return CURLE_OUT_OF_MEMORY;
}
# ifdef DEBUGBUILD
static void local_print_httpsrr(struct Curl_easy *data,
struct Curl_https_rrinfo *hrr)
{
DEBUGASSERT(hrr);
infof(data, "HTTPS RR: priority %d, target: %s",
hrr->priority, hrr->target);
if(hrr->alpns)
infof(data, "HTTPS RR: alpns %s", hrr->alpns);
else
infof(data, "HTTPS RR: no alpns");
if(hrr->no_def_alpn)
infof(data, "HTTPS RR: no_def_alpn set");
else
infof(data, "HTTPS RR: no_def_alpn not set");
if(hrr->ipv4hints) {
local_print_buf(data, "HTTPS RR: ipv4hints",
hrr->ipv4hints, hrr->ipv4hints_len);
}
else
infof(data, "HTTPS RR: no ipv4hints");
if(hrr->echconfiglist) {
local_print_buf(data, "HTTPS RR: ECHConfigList",
hrr->echconfiglist, hrr->echconfiglist_len);
}
else
infof(data, "HTTPS RR: no ECHConfigList");
if(hrr->ipv6hints) {
local_print_buf(data, "HTTPS RR: ipv6hint",
hrr->ipv6hints, hrr->ipv6hints_len);
}
else
infof(data, "HTTPS RR: no ipv6hints");
return;
}
# endif
#endif
CURLcode Curl_doh_is_resolved(struct Curl_easy *data,
struct Curl_dns_entry **dnsp)
{
CURLcode result;
struct dohdata *dohp = data->req.doh;
*dnsp = NULL; /* defaults to no response */
if(!dohp)
return CURLE_OUT_OF_MEMORY;
if(!dohp->probe[DOH_PROBE_SLOT_IPADDR_V4].easy &&
!dohp->probe[DOH_PROBE_SLOT_IPADDR_V6].easy) {
failf(data, "Could not DoH-resolve: %s", data->state.async.hostname);
return CONN_IS_PROXIED(data->conn)?CURLE_COULDNT_RESOLVE_PROXY:
CURLE_COULDNT_RESOLVE_HOST;
}
else if(!dohp->pending) {
#ifndef USE_HTTPSRR
DOHcode rc[DOH_PROBE_SLOTS] = {
DOH_OK, DOH_OK
};
#else
DOHcode rc[DOH_PROBE_SLOTS] = {
DOH_OK, DOH_OK, DOH_OK
};
#endif
struct dohentry de;
int slot;
/* remove DoH handles from multi handle and close them */
Curl_doh_close(data);
/* parse the responses, create the struct and return it! */
de_init(&de);
for(slot = 0; slot < DOH_PROBE_SLOTS; slot++) {
struct dnsprobe *p = &dohp->probe[slot];
if(!p->dnstype)
continue;
rc[slot] = doh_decode(Curl_dyn_uptr(&p->serverdoh),
Curl_dyn_len(&p->serverdoh),
p->dnstype,
&de);
Curl_dyn_free(&p->serverdoh);
#ifndef CURL_DISABLE_VERBOSE_STRINGS
if(rc[slot]) {
infof(data, "DoH: %s type %s for %s", doh_strerror(rc[slot]),
type2name(p->dnstype), dohp->host);
}
#endif
} /* next slot */
result = CURLE_COULDNT_RESOLVE_HOST; /* until we know better */
if(!rc[DOH_PROBE_SLOT_IPADDR_V4] || !rc[DOH_PROBE_SLOT_IPADDR_V6]) {
/* we have an address, of one kind or other */
struct Curl_dns_entry *dns;
struct Curl_addrinfo *ai;
if(Curl_trc_ft_is_verbose(data, &Curl_doh_trc)) {
infof(data, "[DoH] hostname: %s", dohp->host);
showdoh(data, &de);
}
result = doh2ai(&de, dohp->host, dohp->port, &ai);
if(result) {
de_cleanup(&de);
return result;
}
if(data->share)
Curl_share_lock(data, CURL_LOCK_DATA_DNS, CURL_LOCK_ACCESS_SINGLE);
/* we got a response, store it in the cache */
dns = Curl_cache_addr(data, ai, dohp->host, 0, dohp->port, FALSE);
if(data->share)
Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
if(!dns) {
/* returned failure, bail out nicely */
Curl_freeaddrinfo(ai);
}
else {
data->state.async.dns = dns;
*dnsp = dns;
result = CURLE_OK; /* address resolution OK */
}
} /* address processing done */
/* Now process any build-specific attributes retrieved from DNS */
#ifdef USE_HTTPSRR
if(de.numhttps_rrs > 0 && result == CURLE_OK && *dnsp) {
struct Curl_https_rrinfo *hrr = NULL;
result = Curl_doh_decode_httpsrr(de.https_rrs->val, de.https_rrs->len,
&hrr);
if(result) {
infof(data, "Failed to decode HTTPS RR");
return result;
}
infof(data, "Some HTTPS RR to process");
# ifdef DEBUGBUILD
local_print_httpsrr(data, hrr);
# endif
(*dnsp)->hinfo = hrr;
}
#endif
/* All done */
de_cleanup(&de);
Curl_safefree(data->req.doh);
return result;
} /* !dohp->pending */
/* else wait for pending DoH transactions to complete */
return CURLE_OK;
}
void Curl_doh_close(struct Curl_easy *data)
{
struct dohdata *doh = data->req.doh;
if(doh) {
size_t slot;
for(slot = 0; slot < DOH_PROBE_SLOTS; slot++) {
if(!doh->probe[slot].easy)
continue;
/* data->multi might already be reset at this time */
if(doh->probe[slot].easy->multi)
curl_multi_remove_handle(doh->probe[slot].easy->multi,
doh->probe[slot].easy);
Curl_close(&doh->probe[slot].easy);
}
}
}
void Curl_doh_cleanup(struct Curl_easy *data)
{
struct dohdata *doh = data->req.doh;
if(doh) {
Curl_doh_close(data);
curl_slist_free_all(doh->headers);
data->req.doh->headers = NULL;
Curl_safefree(data->req.doh);
}
}
#endif /* CURL_DISABLE_DOH */
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