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Curl timeouts issue in NSS

From: Kevin Baughman <>
Date: Wed, 30 Dec 2009 08:43:50 -0800 (PST)

Hi All,

I had sent some email before that I was seeing unwanted retries in curl, and thought it was a result of the connection cache. I've spent a few days debugging a very bizzare case where a server we are talking to is seeing data sent twice. While debugging I spent some time digging into the curl perform stack for a POST. There seems to be an issue in nss.c that might resend data in the case of a timeout. I'm not completely sure if this is our issue, but it seems wrong to me.

In the function Curl_nss_send():

  rc = PR_Send(conn->ssl[sockindex].handle, mem, (int)len, 0, timeout);

  if(rc < 0) {
    err = PR_GetError();

    if(err == PR_IO_TIMEOUT_ERROR) {
      failf(data, "SSL connection timeout");

    failf(conn->data, "SSL write: error %d", err);
    return -1;

This function says it returns the number of bytes actually sent, but I think CURLE_OPERATION_TIMEDOUT is 28. Unless I am missing something, when I walk back up the stack the code would assume that 28 bytes have been sent and then continue sending the rest. The same issue exists in Curl_nss_recv.

I'm attaching a patch to return -1 in this case.



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Received on 2009-12-30