TFTP: add option to suppress TFTP option requests (Part 2)

- Add tests.

- Add an example to CURLOPT_TFTP_NO_OPTIONS.3.

- Add --tftp-no-options to expose CURLOPT_TFTP_NO_OPTIONS.

Bug: https://github.com/curl/curl/issues/481

src/tool_cfgable.h

@@ -183,6 +183,7 @@ struct OperationConfig {
   char *ftp_alternative_to_user;  /* send command if USER/PASS fails */
   int ftp_filemethod;
   long tftp_blksize;        /* TFTP BLKSIZE option */
+  bool tftp_no_options;     /* do not send TFTP options requests */
   bool ignorecl;            /* --ignore-content-length */
   bool disable_sessionid;
 

src/tool_getparam.c

@@ -180,6 +180,7 @@ static const struct LongShort aliases[]= {
   {"$P", "service-name",             TRUE},
   {"$Q", "proto-default",            TRUE},
   {"$R", "expect100-timeout",        TRUE},
+  {"$S", "tftp-no-options",          FALSE},
   {"0",   "http1.0",                 FALSE},
   {"01",  "http1.1",                 FALSE},
   {"02",  "http2",                   FALSE},
@@ -1005,6 +1006,9 @@ ParameterError getparameter(char *flag,    /* f or -long-flag */
         if(err)
           return err;
         break;
+      case 'S': /* --tftp-no-options */
+        config->tftp_no_options = toggle;
+        break;
       }
       break;
     case '#': /* --progress-bar */

src/tool_help.c

@@ -221,7 +221,8 @@ static const char *const helptext[] = {
   "     --tcp-nodelay   Use the TCP_NODELAY option",
   " -t, --telnet-option OPT=VAL  Set telnet option",
   "     --tftp-blksize VALUE  Set TFTP BLKSIZE option (must be >512)",
-  " -z, --time-cond TIME  Transfer based on a time condition",
+  "     --tftp-no-options  Do not send TFTP options requests",
+  " -z, --time-cond TIME   Transfer based on a time condition",
   " -1, --tlsv1         Use >= TLSv1 (SSL)",
   "     --tlsv1.0       Use TLSv1.0 (SSL)",
   "     --tlsv1.1       Use TLSv1.1 (SSL)",

src/tool_operate.c

@@ -1354,6 +1354,10 @@ static CURLcode operate_do(struct GlobalConfig *global,
           my_setopt_str(curl, CURLOPT_EXPECT_100_TIMEOUT_MS,
                         (long)(config->expect100timeout*1000));
 
+        /* new in 7.48.0 */
+        if(config->tftp_no_options)
+          my_setopt(curl, CURLOPT_TFTP_NO_OPTIONS, 1L);
+
         /* initialize retry vars for loop below */
         retry_sleep_default = (config->retry_delay) ?
           config->retry_delay*1000L : RETRY_SLEEP_DEFAULT; /* ms */