Hi! I'm new to ssl and am having some problems. I'm working on an
http server; the interface is in perl and the internals are in perl and
C; the SSL module is in C.
Everything works fine except for large file uploads (using
"multipart/form-data"), where I lose a *variable* fraction of a percent
of the bytes (eg, 1-10 bytes for 20 MB) *in the middle* of the transfer.
Ie, the bytes read do not match the content-length, but while the
multipart boundaries at beginning and end are intact, the file written
out is too short.
The only errors I receive from openssl are WANT_READ or WANT_WRITE,
which I handle like EAGAIN (the socket is non-block). The code which
handles the upload is identical for both SSL and non-SSL connections,
except for the read function below, but there is no such problem with
non-SSL transfers.
The read function uses some of the perl API and is intended to provide
the same functionality as perl's sysread (this is why the rest of the
code is identical to the non-SSL upload):
SV *sysread (SV *objref, SV *buf, int len) {
// retrieve SSL object from perl
HV *self = (HV*)SvRV(objref);
SV **field = hv_fetch(self, "ssl", 3, 0);
if (!field) return newSV(0);
SSL *ssl = (SSL*)SvIV(*field);
// set up buffer and read
unsigned char data[len];
ERR_clear_error();
int bytes = SSL_read(ssl, data, len);
// error handling
if (bytes < 0) {
int err = SSL_get_error(ssl, bytes);
if (err == SSL_ERROR_WANT_READ
|| err == SSL_ERROR_WANT_WRITE) err = EAGAIN;
else err *= -1;
// the error is made negative to prevent collision with EAGAIN
hv_store(self, "readerr", 3, newSViv (err), 0);
return newSV (0); // perl undef
}
// return buffer contents to perl
sv_setpvn(buf, data, bytes);
return newSViv(bytes);
}
As stated, the only error which actually occurs is the WANT_READ or
WANT_WRITE.
I can also post the ctx setup*, etc, tho again, everything works fine
except for large uploads. Large downloads are fine. My test
client is firefox 7 over a slow wireless connection; the loss is less
on local loopback but still occurs. What have I missed about this?
Thanks -- MK
* I use SSL_set_fd and not a BIO.
--
"Enthusiasm is not the enemy of the intellect." (said of Irving Howe)
"The angel of history[...]is turned toward the past." (Walter Benjamin)
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