  struct connectdata *conn = cf->conn;
  unsigned char *socksreq = (unsigned char *)data->state.buffer;
  int idx;
  CURLcode result;
  CURLproxycode presult;
  bool socks5_resolve_local =
    (conn->socks_proxy.proxytype == CURLPROXY_SOCKS5) ? TRUE : FALSE;
  const size_t hostname_len = strlen(sx->hostname);
  ssize_t len = 0;
…
  case CONNECT_SOCKS_INIT:
    if(conn->bits.httpproxy)
      infof(data, "SOCKS5: connecting to HTTP proxy %s port %d",
            sx->hostname, sx->remote_port);

    /* RFC1928 chapter 5 specifies max 255 chars for domain name in packet */
    if(!socks5_resolve_local && hostname_len > 255) {
      infof(data, "SOCKS5: server resolving disabled for hostnames of "
            "length > 255 [actual len=%zu]", hostname_len);
      socks5_resolve_local = TRUE;
    }
…
  case CONNECT_SOCKS_READ:
    presult = socks_state_recv(cf, sx, data, CURLPX_RECV_CONNECT,
                               "initial SOCKS5 response");
    if(CURLPX_OK != presult)
      return presult;
    else if(sx->outstanding) {
      /* remain in reading state */
      return CURLPX_OK;
    }
    else if(socksreq[0] != 5) {
…
  case CONNECT_RESOLVE_REMOTE:
    /* Authentication is complete, now specify destination to the proxy */
    len = 0;
    socksreq[len++] = 5; /* version (SOCKS5) */
    socksreq[len++] = 1; /* connect */
    socksreq[len++] = 0; /* must be zero */

    if(!socks5_resolve_local) {
      /* ATYP: domain name = 3,
…
      }
      else {
        socksreq[len++] = 3;
        socksreq[len++] = (char) hostname_len; /* one byte address length */
        memcpy(&socksreq[len], sx->hostname, hostname_len); /* w/o NULL */
        len += hostname_len;
      }

Échauffement