CURLOPT_BUFFERSIZE: support enlarging receive buffer

Replace use of fixed macro BUFSIZE to define the size of the receive
buffer.  Reappropriate CURLOPT_BUFFERSIZE to include enlarging receive
buffer size.  Upon setting, resize buffer if larger than the current
default size up to a MAX_BUFSIZE (512KB). This can benefit protocols
like SFTP.

Closes #1222

7 files changed, 42 insertions, 11 deletions

diff --git a/lib/easy.c b/lib/easy.c
index 1242369d5..bed94a444 100644
--- a/lib/easy.c
+++ b/lib/easy.c
@@ -870,6 +870,11 @@ struct Curl_easy *curl_easy_duphandle(struct Curl_easy *data)
    * get setup on-demand in the code, as that would probably decrease
    * the likeliness of us forgetting to init a buffer here in the future.
    */
+  outcurl->set.buffer_size = data->set.buffer_size;
+  outcurl->state.buffer = malloc(CURL_BUFSIZE(outcurl->set.buffer_size) + 1);
+  if(!outcurl->state.buffer)
+    goto fail;
+
   outcurl->state.headerbuff = malloc(HEADERSIZE);
   if(!outcurl->state.headerbuff)
     goto fail;
@@ -940,6 +945,7 @@ struct Curl_easy *curl_easy_duphandle(struct Curl_easy *data)
   if(outcurl) {
     curl_slist_free_all(outcurl->change.cookielist);
     outcurl->change.cookielist = NULL;
+    Curl_safefree(outcurl->state.buffer);
     Curl_safefree(outcurl->state.headerbuff);
     Curl_safefree(outcurl->change.url);
     Curl_safefree(outcurl->change.referer);
diff --git a/lib/file.c b/lib/file.c
index 3dbc0f2b8..e90902c50 100644
--- a/lib/file.c
+++ b/lib/file.c
@@ -476,7 +476,7 @@ static CURLcode file_do(struct connectdata *conn, bool *done)
     time_t filetime;
     struct tm buffer;
     const struct tm *tm = &buffer;
-    snprintf(buf, sizeof(data->state.buffer),
+    snprintf(buf, CURL_BUFSIZE(data->set.buffer_size),
              "Content-Length: %" CURL_FORMAT_CURL_OFF_T "\r\n", expected_size);
     result = Curl_client_write(conn, CLIENTWRITE_BOTH, buf, 0);
     if(result)
diff --git a/lib/ftp.c b/lib/ftp.c
index 6a094df08..aa4d5ac2d 100644
--- a/lib/ftp.c
+++ b/lib/ftp.c
@@ -2107,7 +2107,7 @@ static CURLcode ftp_state_mdtm_resp(struct connectdata *conn,
         /* we have a time, reformat it */
         time_t secs=time(NULL);
         /* using the good old yacc/bison yuck */
-        snprintf(buf, sizeof(conn->data->state.buffer),
+        snprintf(buf, CURL_BUFSIZE(conn->data->set.buffer_size),
                  "%04d%02d%02d %02d:%02d:%02d GMT",
                  year, month, day, hour, minute, second);
         /* now, convert this into a time() value: */
@@ -2318,7 +2318,7 @@ static CURLcode ftp_state_size_resp(struct connectdata *conn,
   if(instate == FTP_SIZE) {
 #ifdef CURL_FTP_HTTPSTYLE_HEAD
     if(-1 != filesize) {
-      snprintf(buf, sizeof(data->state.buffer),
+      snprintf(buf, CURL_BUFSIZE(data->set.buffer_size),
                "Content-Length: %" CURL_FORMAT_CURL_OFF_T "\r\n", filesize);
       result = Curl_client_write(conn, CLIENTWRITE_BOTH, buf, 0);
       if(result)
@@ -2823,6 +2823,7 @@ static CURLcode ftp_statemach_act(struct connectdata *conn)
     case FTP_PWD:
       if(ftpcode == 257) {
         char *ptr=&data->state.buffer[4];  /* start on the first letter */
+        const size_t buf_size = CURL_BUFSIZE(data->set.buffer_size);
         char *dir;
         char *store;
 
@@ -2840,7 +2841,7 @@ static CURLcode ftp_statemach_act(struct connectdata *conn)
         */
 
         /* scan for the first double-quote for non-standard responses */
-        while(ptr < &data->state.buffer[sizeof(data->state.buffer)]
+        while(ptr < &data->state.buffer[buf_size]
               && *ptr != '\n' && *ptr != '\0' && *ptr != '"')
           ptr++;
 
diff --git a/lib/http.c b/lib/http.c
index fdaecafdc..2066520e7 100644
--- a/lib/http.c
+++ b/lib/http.c
@@ -297,7 +297,8 @@ static CURLcode http_output_basic(struct connectdata *conn, bool proxy)
     pwd = conn->passwd;
   }
 
-  snprintf(data->state.buffer, sizeof(data->state.buffer), "%s:%s", user, pwd);
+  snprintf(data->state.buffer, CURL_BUFSIZE(data->set.buffer_size),
+           "%s:%s", user, pwd);
 
   result = Curl_base64_encode(data,
                               data->state.buffer, strlen(data->state.buffer),
diff --git a/lib/telnet.c b/lib/telnet.c
index 551af60f2..8ee7efa4c 100644
--- a/lib/telnet.c
+++ b/lib/telnet.c
@@ -1416,6 +1416,7 @@ static CURLcode telnet_do(struct connectdata *conn, bool *done)
 
   /* Keep on listening and act on events */
   while(keepon) {
+    const size_t buf_size = CURL_BUFSIZE(data->set.buffer_size);
     waitret = WaitForMultipleObjects(obj_count, objs, FALSE, wait_timeout);
     switch(waitret) {
     case WAIT_TIMEOUT:
@@ -1451,7 +1452,7 @@ static CURLcode telnet_do(struct connectdata *conn, bool *done)
           if(!readfile_read)
             break;
 
-          if(!ReadFile(stdin_handle, buf, sizeof(data->state.buffer),
+          if(!ReadFile(stdin_handle, buf, buf_size,
                        &readfile_read, NULL)) {
             keepon = FALSE;
             result = CURLE_READ_ERROR;
@@ -1470,7 +1471,7 @@ static CURLcode telnet_do(struct connectdata *conn, bool *done)
 
     case WAIT_OBJECT_0 + 1:
     {
-      if(!ReadFile(stdin_handle, buf, sizeof(data->state.buffer),
+      if(!ReadFile(stdin_handle, buf, buf_size,
                    &readfile_read, NULL)) {
         keepon = FALSE;
         result = CURLE_READ_ERROR;
diff --git a/lib/url.c b/lib/url.c
index 1434d8f80..f5039bad8 100644
--- a/lib/url.c
+++ b/lib/url.c
@@ -452,6 +452,7 @@ CURLcode Curl_close(struct Curl_easy *data)
   }
   data->change.url = NULL;
 
+  Curl_safefree(data->state.buffer);
   Curl_safefree(data->state.headerbuff);
 
   Curl_flush_cookies(data, 1);
@@ -641,6 +642,12 @@ CURLcode Curl_open(struct Curl_easy **curl)
 
   /* We do some initial setup here, all those fields that can't be just 0 */
 
+  data->state.buffer = malloc(BUFSIZE + 1);
+  if(!data->state.buffer) {
+    DEBUGF(fprintf(stderr, "Error: malloc of buffer failed\n"));
+    result = CURLE_OUT_OF_MEMORY;
+  }
+
   data->state.headerbuff = malloc(HEADERSIZE);
   if(!data->state.headerbuff) {
     DEBUGF(fprintf(stderr, "Error: malloc of headerbuff failed\n"));
@@ -671,6 +678,7 @@ CURLcode Curl_open(struct Curl_easy **curl)
 
   if(result) {
     Curl_resolver_cleanup(data->state.resolver);
+    free(data->state.buffer);
     free(data->state.headerbuff);
     Curl_freeset(data);
     free(data);
@@ -2268,9 +2276,20 @@ CURLcode Curl_setopt(struct Curl_easy *data, CURLoption option,
      */
     data->set.buffer_size = va_arg(param, long);
 
-    if((data->set.buffer_size> (BUFSIZE -1)) ||
-       (data->set.buffer_size < 1))
-      data->set.buffer_size = 0; /* huge internal default */
+    if(data->set.buffer_size > MAX_BUFSIZE)
+      data->set.buffer_size = MAX_BUFSIZE; /* huge internal default */
+    else if(data->set.buffer_size < 1)
+      data->set.buffer_size = BUFSIZE;
+
+    /* Resize only if larger than default buffer size. */
+    if(data->set.buffer_size > BUFSIZE) {
+      data->state.buffer = realloc(data->state.buffer,
+                                   data->set.buffer_size + 1);
+      if(!data->state.buffer) {
+        DEBUGF(fprintf(stderr, "Error: realloc of buffer failed\n"));
+        result = CURLE_OUT_OF_MEMORY;
+      }
+    }
 
     break;
 
diff --git a/lib/urldata.h b/lib/urldata.h
index 96c0aca19..20057effa 100644
--- a/lib/urldata.h
+++ b/lib/urldata.h
@@ -201,6 +201,9 @@
 /* Download buffer size, keep it fairly big for speed reasons */
 #undef BUFSIZE
 #define BUFSIZE CURL_MAX_WRITE_SIZE
+#undef MAX_BUFSIZE
+#define MAX_BUFSIZE CURL_MAX_READ_SIZE
+#define CURL_BUFSIZE(x) ((x)?(x):(BUFSIZE))
 
 /* Initial size of the buffer to store headers in, it'll be enlarged in case
    of need. */
@@ -1304,7 +1307,7 @@ struct UrlState {
   char *headerbuff; /* allocated buffer to store headers in */
   size_t headersize;   /* size of the allocation */
 
-  char buffer[BUFSIZE+1]; /* download buffer */
+  char *buffer; /* download buffer */
   char uploadbuffer[BUFSIZE+1]; /* upload buffer */
   curl_off_t current_speed;  /* the ProgressShow() funcion sets this,
                                 bytes / second */