From 44b4cc95e8b3fcdba46f2727711805b0feebacd1 Mon Sep 17 00:00:00 2001
From: Michael Koenig <michael.koenig@lancom.de>
Date: Mon, 17 Aug 2015 17:54:47 +0200
Subject: [PATCH] TFTP: added option to suppress TFTP option requests

Some TFTP server implementations ignore the "TFTP Option extension"
(RFC 1782-1784, 2347-2349), or implement it in a flawed way, causing
problems with libcurl. Another switch for curl_easy_setopt
"CURLOPT_TFTP_NO_OPTIONS" is introduced which prevents libcurl from
sending TFTP option requests to a server, avoiding many problems caused
by faulty implementations.
---
 include/curl/curl.h |  3 +++
 lib/tftp.c          | 57 ++++++++++++++++++++++++++++-------------------------
 lib/url.c           |  9 ++++++++-
 lib/urldata.h       |  1 +
 4 files changed, 42 insertions(+), 28 deletions(-)

diff --git a/include/curl/curl.h b/include/curl/curl.h
index 64f9261..cb23872 100644
--- a/include/curl/curl.h
+++ b/include/curl/curl.h
@@ -1645,6 +1645,9 @@ typedef enum {
   /* Wait/don't wait for pipe/mutex to clarify */
   CINIT(PIPEWAIT, LONG, 237),
 
+  /* do not send any tftp option requests to the server */
+  CINIT(TFTP_NO_OPTIONS, LONG, 238),
+
   CURLOPT_LASTENTRY /* the last unused */
 } CURLoption;
 
diff --git a/lib/tftp.c b/lib/tftp.c
index 4c5796f..164a538 100644
--- a/lib/tftp.c
+++ b/lib/tftp.c
@@ -494,33 +494,36 @@ static CURLcode tftp_send_first(tftp_state_data_t *state, tftp_event_t event)
              "%s%c%s%c", filename, '\0',  mode, '\0');
     sbytes = 4 + strlen(filename) + strlen(mode);
 
-    /* add tsize option */
-    if(data->set.upload && (data->state.infilesize != -1))
-      snprintf(buf, sizeof(buf), "%" CURL_FORMAT_CURL_OFF_T,
-               data->state.infilesize);
-    else
-      strcpy(buf, "0"); /* the destination is large enough */
-
-    sbytes += tftp_option_add(state, sbytes,
-                              (char *)state->spacket.data+sbytes,
-                              TFTP_OPTION_TSIZE);
-    sbytes += tftp_option_add(state, sbytes,
-                              (char *)state->spacket.data+sbytes, buf);
-    /* add blksize option */
-    snprintf( buf, sizeof(buf), "%d", state->requested_blksize );
-    sbytes += tftp_option_add(state, sbytes,
-                              (char *)state->spacket.data+sbytes,
-                              TFTP_OPTION_BLKSIZE);
-    sbytes += tftp_option_add(state, sbytes,
-                              (char *)state->spacket.data+sbytes, buf );
-
-    /* add timeout option */
-    snprintf( buf, sizeof(buf), "%d", state->retry_time);
-    sbytes += tftp_option_add(state, sbytes,
-                              (char *)state->spacket.data+sbytes,
-                              TFTP_OPTION_INTERVAL);
-    sbytes += tftp_option_add(state, sbytes,
-                              (char *)state->spacket.data+sbytes, buf );
+    /* optional addition of TFTP options */
+    if(!data->set.tftp_no_options) {
+      /* add tsize option */
+      if(data->set.upload && (data->state.infilesize != -1))
+        snprintf(buf, sizeof(buf), "%" CURL_FORMAT_CURL_OFF_T,
+                 data->state.infilesize);
+      else
+        strcpy(buf, "0"); /* the destination is large enough */
+
+      sbytes += tftp_option_add(state, sbytes,
+                                (char *)state->spacket.data+sbytes,
+                                TFTP_OPTION_TSIZE);
+      sbytes += tftp_option_add(state, sbytes,
+                                (char *)state->spacket.data+sbytes, buf);
+      /* add blksize option */
+      snprintf( buf, sizeof(buf), "%d", state->requested_blksize );
+      sbytes += tftp_option_add(state, sbytes,
+                                (char *)state->spacket.data+sbytes,
+                                TFTP_OPTION_BLKSIZE);
+      sbytes += tftp_option_add(state, sbytes,
+                                (char *)state->spacket.data+sbytes, buf );
+
+      /* add timeout option */
+      snprintf( buf, sizeof(buf), "%d", state->retry_time);
+      sbytes += tftp_option_add(state, sbytes,
+                                (char *)state->spacket.data+sbytes,
+                                TFTP_OPTION_INTERVAL);
+      sbytes += tftp_option_add(state, sbytes,
+                                (char *)state->spacket.data+sbytes, buf );
+    }
 
     /* the typecase for the 3rd argument is mostly for systems that do
        not have a size_t argument, like older unixes that want an 'int' */
diff --git a/lib/url.c b/lib/url.c
index 406c1f0..9e27835 100644
--- a/lib/url.c
+++ b/lib/url.c
@@ -837,9 +837,16 @@ CURLcode Curl_setopt(struct SessionHandle *data, CURLoption option,
      */
     data->set.server_response_timeout = va_arg( param , long ) * 1000;
     break;
+  case CURLOPT_TFTP_NO_OPTIONS:
+    /*
+     * Option that prevents libcurl from sending TFTP option requests to the
+     * server.
+     */
+    data->set.tftp_no_options = va_arg(param, long) != 0;
+    break;
   case CURLOPT_TFTP_BLKSIZE:
     /*
-     * TFTP option that specifies the block size to use for data transmission
+     * TFTP option that specifies the block size to use for data transmission.
      */
     data->set.tftp_blksize = va_arg(param, long);
     break;
diff --git a/lib/urldata.h b/lib/urldata.h
index b1c2056..f4d6227 100644
--- a/lib/urldata.h
+++ b/lib/urldata.h
@@ -1485,6 +1485,7 @@ struct UserDefined {
   long accepttimeout;   /* in milliseconds, 0 means no timeout */
   long server_response_timeout; /* in milliseconds, 0 means no timeout */
   long tftp_blksize ; /* in bytes, 0 means use default */
+  bool tftp_no_options ; /* true -> do not ask for any options */
   curl_off_t filesize;  /* size of file to upload, -1 means unknown */
   long low_speed_limit; /* bytes/second */
   long low_speed_time;  /* number of seconds */
-- 
1.8.4.msysgit.0