doh: disable DOH for the cases it doesn't work

Due to limitations in Curl_resolver_wait_resolv(), it doesn't work for
DOH resolves. This fix disables DOH for those.

Limitation added to KNOWN_BUGS.

Fixes #3850
Closes #3857

docs/KNOWN_BUGS

@@ -19,6 +19,7 @@ problems may have been fixed or changed somewhat since this was written!
  1.5 Expect-100 meets 417
  1.6 Unnecessary close when 401 received waiting for 100
  1.7 Deflate error after all content was received
+ 1.8 DoH isn't used for all name resolves when enabled
  1.9 HTTP/2 frames while in the connection pool kill reuse
  1.10 Strips trailing dot from host name
  1.11 CURLOPT_SEEKFUNCTION not called with CURLFORM_STREAM
@@ -166,6 +167,16 @@ problems may have been fixed or changed somewhat since this was written!
 
  See https://github.com/curl/curl/issues/2719
 
+1.8 DoH isn't used for all name resolves when enabled
+
+ Even if DoH is specified to be used, there are some name resolves that are
+ done without it. This should be fixed. When the internal function
+ `Curl_resolver_wait_resolv()` is called, it doesn't use DoH to complete the
+ resolve as it otherwise should.
+
+ See https://github.com/curl/curl/pull/3857 and
+ https://github.com/curl/curl/pull/3850
+
 1.9 HTTP/2 frames while in the connection pool kill reuse
 
  If the server sends HTTP/2 frames (like for example an HTTP/2 PING frame) to

lib/connect.c

@@ -357,7 +357,7 @@ static CURLcode bindlocal(struct connectdata *conn,
         conn->ip_version = CURL_IPRESOLVE_V6;
 #endif
 
-      rc = Curl_resolv(conn, dev, 0, &h);
+      rc = Curl_resolv(conn, dev, 0, FALSE, &h);
       if(rc == CURLRESOLV_PENDING)
         (void)Curl_resolver_wait_resolv(conn, &h);
       conn->ip_version = ipver;

lib/ftp.c

@@ -1080,7 +1080,7 @@ static CURLcode ftp_state_use_port(struct connectdata *conn,
   }
 
   /* resolv ip/host to ip */
-  rc = Curl_resolv(conn, host, 0, &h);
+  rc = Curl_resolv(conn, host, 0, FALSE, &h);
   if(rc == CURLRESOLV_PENDING)
     (void)Curl_resolver_wait_resolv(conn, &h);
   if(h) {
@@ -1934,7 +1934,7 @@ static CURLcode ftp_state_pasv_resp(struct connectdata *conn,
      */
     const char * const host_name = conn->bits.socksproxy ?
       conn->socks_proxy.host.name : conn->http_proxy.host.name;
-    rc = Curl_resolv(conn, host_name, (int)conn->port, &addr);
+    rc = Curl_resolv(conn, host_name, (int)conn->port, FALSE, &addr);
     if(rc == CURLRESOLV_PENDING)
       /* BLOCKING, ignores the return code but 'addr' will be NULL in
          case of failure */
@@ -1950,7 +1950,7 @@ static CURLcode ftp_state_pasv_resp(struct connectdata *conn,
   }
   else {
     /* normal, direct, ftp connection */
-    rc = Curl_resolv(conn, ftpc->newhost, ftpc->newport, &addr);
+    rc = Curl_resolv(conn, ftpc->newhost, ftpc->newport, FALSE, &addr);
     if(rc == CURLRESOLV_PENDING)
       /* BLOCKING */
       (void)Curl_resolver_wait_resolv(conn, &addr);

lib/hostip.c

@@ -482,6 +482,7 @@ Curl_cache_addr(struct Curl_easy *data,
 int Curl_resolv(struct connectdata *conn,
                 const char *hostname,
                 int port,
+                bool allowDOH,
                 struct Curl_dns_entry **entry)
 {
   struct Curl_dns_entry *dns = NULL;
@@ -527,7 +528,7 @@ int Curl_resolv(struct connectdata *conn,
         return CURLRESOLV_ERROR;
     }
 
-    if(data->set.doh) {
+    if(allowDOH && data->set.doh) {
       addr = Curl_doh(conn, hostname, port, &respwait);
     }
     else {
@@ -653,7 +654,7 @@ int Curl_resolv_timeout(struct connectdata *conn,
 
   if(!timeout)
     /* USE_ALARM_TIMEOUT defined, but no timeout actually requested */
-    return Curl_resolv(conn, hostname, port, entry);
+    return Curl_resolv(conn, hostname, port, TRUE, entry);
 
   if(timeout < 1000) {
     /* The alarm() function only provides integer second resolution, so if
@@ -715,7 +716,7 @@ int Curl_resolv_timeout(struct connectdata *conn,
   /* Perform the actual name resolution. This might be interrupted by an
    * alarm if it takes too long.
    */
-  rc = Curl_resolv(conn, hostname, port, entry);
+  rc = Curl_resolv(conn, hostname, port, TRUE, entry);
 
 #ifdef USE_ALARM_TIMEOUT
 clean_up:

lib/hostip.h

@@ -83,8 +83,11 @@ struct Curl_dns_entry {
 #define CURLRESOLV_ERROR    -1
 #define CURLRESOLV_RESOLVED  0
 #define CURLRESOLV_PENDING   1
-int Curl_resolv(struct connectdata *conn, const char *hostname,
+int Curl_resolv(struct connectdata *conn,
-                int port, struct Curl_dns_entry **dnsentry);
+                const char *hostname,
+                int port,
+                bool allowDOH,
+                struct Curl_dns_entry **dnsentry);
 int Curl_resolv_timeout(struct connectdata *conn, const char *hostname,
                         int port, struct Curl_dns_entry **dnsentry,
                         time_t timeoutms);

lib/socks.c

@@ -155,7 +155,7 @@ CURLcode Curl_SOCKS4(const char *proxy_user,
     Curl_addrinfo *hp = NULL;
     int rc;
 
-    rc = Curl_resolv(conn, hostname, remote_port, &dns);
+    rc = Curl_resolv(conn, hostname, remote_port, FALSE, &dns);
 
     if(rc == CURLRESOLV_ERROR)
       return CURLE_COULDNT_RESOLVE_PROXY;
@@ -609,7 +609,7 @@ CURLcode Curl_SOCKS5(const char *proxy_user,
   else {
     struct Curl_dns_entry *dns;
     Curl_addrinfo *hp = NULL;
-    int rc = Curl_resolv(conn, hostname, remote_port, &dns);
+    int rc = Curl_resolv(conn, hostname, remote_port, FALSE, &dns);
 
     if(rc == CURLRESOLV_ERROR)
       return CURLE_COULDNT_RESOLVE_HOST;