urldata: connection bit ipv6_ip is wrong

Eliminate `conn->bits.ipv6_ip`

The bit was only correct for the first transfer using a connection. Use
`data->state.up.hostname` instead in places that need the URL hostname
in its original form.

Fix parseurlandfillconn() to not modify `data->state.up.hostname` before
copying the connection's hostname, but modify the copy instead, leaving
the URL hostname intact.

Closes #20919

lib/http.c

@@ -2068,9 +2068,9 @@ static CURLcode http_set_aptr_host(struct Curl_easy *data)
     }
   }
   else {
-    /* When building Host: headers, we must put the hostname within
-       [brackets] if the hostname is a plain IPv6-address. RFC2732-style. */
-    const char *host = conn->host.name;
+    /* Use the hostname as present in the URL if it was IPv6. */
+    char *host = (data->state.up.hostname[0] == '[') ?
+       data->state.up.hostname : conn->host.name;
 
     if(((conn->given->protocol & (CURLPROTO_HTTPS | CURLPROTO_WSS)) &&
         (conn->remote_port == PORT_HTTPS)) ||
@@ -2078,14 +2078,9 @@ static CURLcode http_set_aptr_host(struct Curl_easy *data)
         (conn->remote_port == PORT_HTTP)))
       /* if(HTTPS on port 443) OR (HTTP on port 80) then do not include
          the port number in the host string */
-      aptr->host = curl_maprintf("Host: %s%s%s\r\n",
-                                 conn->bits.ipv6_ip ? "[" : "",
-                                 host, conn->bits.ipv6_ip ? "]" : "");
+      aptr->host = curl_maprintf("Host: %s\r\n", host);
     else
-      aptr->host = curl_maprintf("Host: %s%s%s:%d\r\n",
-                                 conn->bits.ipv6_ip ? "[" : "",
-                                 host, conn->bits.ipv6_ip ? "]" : "",
-                                 conn->remote_port);
+      aptr->host = curl_maprintf("Host: %s:%d\r\n", host, conn->remote_port);
 
     if(!aptr->host)
       /* without Host: we cannot make a nice request */

lib/http_proxy.c

@@ -183,10 +183,7 @@ void Curl_http_proxy_get_destination(struct Curl_cfilter *cf,
   else
     *pport = cf->conn->remote_port;
 
-  if(*phostname != cf->conn->host.name)
-    *pipv6_ip = (strchr(*phostname, ':') != NULL);
-  else
-    *pipv6_ip = (bool)cf->conn->bits.ipv6_ip;
+  *pipv6_ip = (strchr(*phostname, ':') != NULL);
 }
 
 struct cf_proxy_ctx {

lib/openldap.c

@@ -614,11 +614,10 @@ static CURLcode oldap_connect(struct Curl_easy *data, bool *done)
   if(result)
     goto out;
 
-  hosturl = curl_maprintf("%s://%s%s%s:%d",
+  hosturl = curl_maprintf("%s://%s:%d",
                           conn->scheme->name,
-                          conn->bits.ipv6_ip ? "[" : "",
-                          conn->host.name,
-                          conn->bits.ipv6_ip ? "]" : "",
+                          (data->state.up.hostname[0] == '[') ?
+                          data->state.up.hostname : conn->host.name,
                           conn->remote_port);
   if(!hosturl) {
     result = CURLE_OUT_OF_MEMORY;

lib/socks.c

@@ -790,7 +790,7 @@ static CURLproxycode socks5_req1_init(struct socks_state *sx,
 
   /* remote resolving, send what type+addr/string to resolve */
 #ifdef USE_IPV6
-  if(cf->conn->bits.ipv6_ip) {
+  if(strchr(sx->hostname, ':')) {
     desttype = 4;
     destination = ipbuf;
     destlen = 16;

lib/url.c

@@ -1609,6 +1609,7 @@ static CURLcode parseurlandfillconn(struct Curl_easy *data,
   CURLU *uh;
   CURLUcode uc;
   char *hostname;
+  size_t hlen;
   bool use_set_uh = (data->set.uh && !data->state.this_is_a_follow);
 
   up_free(data); /* cleanup previous leftovers first */
@@ -1667,17 +1668,16 @@ static CURLcode parseurlandfillconn(struct Curl_easy *data,
     failf(data, "Too long hostname (maximum is %d)", MAX_URL_LEN);
     return CURLE_URL_MALFORMAT;
   }
+
   hostname = data->state.up.hostname;
+  hlen = hostname ? strlen(hostname) : 0;
 
   if(hostname && hostname[0] == '[') {
     /* This looks like an IPv6 address literal. See if there is an address
        scope. */
-    size_t hlen;
-    conn->bits.ipv6_ip = TRUE;
-    /* cut off the brackets! */
+    /* cut off the brackets after copying this! */
     hostname++;
-    hlen = strlen(hostname);
-    hostname[hlen - 1] = 0;
+    hlen -= 2;
 
     zonefrom_url(uh, data, conn);
   }
@@ -1686,6 +1686,7 @@ static CURLcode parseurlandfillconn(struct Curl_easy *data,
   conn->host.rawalloc = curlx_strdup(hostname ? hostname : "");
   if(!conn->host.rawalloc)
     return CURLE_OUT_OF_MEMORY;
+  conn->host.rawalloc[hlen] = 0; /* cut off for ipv6 case */
   conn->host.name = conn->host.rawalloc;
 
   /*************************************************************
@@ -2817,19 +2818,14 @@ static CURLcode parse_connect_to_string(struct Curl_easy *data,
     ptr++;
   }
   else {
-    /* check whether the URL's hostname matches */
-    size_t hostname_to_match_len;
-    char *hostname_to_match = curl_maprintf("%s%s%s",
-                                            conn->bits.ipv6_ip ? "[" : "",
-                                            conn->host.name,
-                                            conn->bits.ipv6_ip ? "]" : "");
-    if(!hostname_to_match)
-      return CURLE_OUT_OF_MEMORY;
-    hostname_to_match_len = strlen(hostname_to_match);
-    host_match = curl_strnequal(ptr, hostname_to_match,
-                                hostname_to_match_len);
-    curlx_free(hostname_to_match);
-    ptr += hostname_to_match_len;
+    /* check whether the URL's hostname matches. Use the url hostname
+     * when it was an IPv6 address. Otherwise use the connection's hostname
+     * that has IDN conversion. */
+    char *hostname_to_match = (data->state.up.hostname[0] == '[') ?
+       data->state.up.hostname : conn->host.name;
+    size_t hlen = strlen(hostname_to_match);
+    host_match = curl_strnequal(ptr, hostname_to_match, hlen);
+    ptr += hlen;
 
     host_match = host_match && *ptr == ':';
     ptr++;

lib/urldata.h

@@ -338,8 +338,6 @@ struct ConnectBits {
                         that overrides the host in the URL */
   BIT(conn_to_port); /* if set, this connection has a "connect to port"
                         that overrides the port in the URL (remote port) */
-  BIT(ipv6_ip); /* we communicate with a remote site specified with pure IPv6
-                   IP address */
   BIT(ipv6);    /* we communicate with a site using an IPv6 address */
   BIT(do_more); /* this is set TRUE if the ->curl_do_more() function is
                    supposed to be called, after ->curl_do() */

lib/vssh/libssh.c

@@ -2422,13 +2422,9 @@ static CURLcode myssh_connect(struct Curl_easy *data, bool *done)
     return CURLE_FAILED_INIT;
   }
 
-  if(conn->bits.ipv6_ip) {
-    char ipv6[MAX_IPADR_LEN];
-    curl_msnprintf(ipv6, sizeof(ipv6), "[%s]", conn->host.name);
-    rc = ssh_options_set(sshc->ssh_session, SSH_OPTIONS_HOST, ipv6);
-  }
-  else
-    rc = ssh_options_set(sshc->ssh_session, SSH_OPTIONS_HOST, conn->host.name);
+  rc = ssh_options_set(sshc->ssh_session, SSH_OPTIONS_HOST,
+                       (data->state.up.hostname[0] == '[') ?
+                       data->state.up.hostname : conn->host.name);
 
   if(rc != SSH_OK) {
     failf(data, "Could not set remote host");

tests/data/test2053

@@ -31,7 +31,7 @@ Connect to specific host with IP addresses
 
 <command>
 http://10.0.0.1:8081/%TESTNUMBER  --connect-to 10.0.0.1:8081:%HOSTIP:%HTTPPORT --next
-http://[fc00::1]:8082/%TESTNUMBER --connect-to [fc00::1]:8082:%HOSTIP:%HTTPPORT
+http://[fc00::1]:8081/%TESTNUMBER --connect-to [fc00::1]:8081:%HOSTIP:%HTTPPORT
 </command>
 </client>
 
@@ -44,7 +44,7 @@ User-Agent: curl/%VERSION
 Accept: */*
 
 GET /%TESTNUMBER HTTP/1.1
-Host: [fc00::1]:8082
+Host: [fc00::1]:8081
 User-Agent: curl/%VERSION
 Accept: */*