Hi.
Guy Harris wrote:
>
> On Tue, Jul 16, 2002 at 09:21:17AM -0700, Fulvio Risso wrote:
> > We're going to release a preview of the new WinPcap which has a new
> > pcap_read_ex(), which does what you're looking for.
>
> It should also be possible to implement "pcap_setnonblock()" and
> "pcap_getnonblock()" for WinPcap.
They are already implemented.
The fact is that we believe the actual API is a bit confusing, so in our
docs we suggest not to use these calls.
Instead, we defined a pcap_read_ex() which reads a packet at a time
(like pcap_next() ), it is non blocking, and returns
- (1) if a packet has been read without problems
- (0) if the timeout set with pcap_open_live() has elapsed. In this case
pkt_header and pkt_data don't point to a valid packet
- (-1) if an error occurred
- (-2) if EOF was reached reading from an offline capture
We believe this is much simpler than having to deal with noblocking and
such things.
fulvio
>
> Add "int" fields "timeout" and "nonblock" to the set of Win32-specific
> fields in a "struct pcap".
>
> In "pcap_open_live()", set "timeout" to the "to_ms" argument and set
> "nonblock" to 1 if "to_ms" is -1 and 0 otherwise.
>
> "pcap_setnonblock()" and "pcap_getnonblock()" would be
>
> /*
> * NOTE: in the future, these may need to call platform-dependent routines,
> * e.g. on platforms with memory-mapped packet-capture mechanisms where
> * "pcap_read()" uses "select()" or "poll()" to wait for packets to arrive.
> */
> int
> pcap_getnonblock(pcap_t *p, char *errbuf)
> {
> #ifndef WIN32
> int fdflags;
> #endif
>
> if (p->sf.rfile != NULL) {
> /*
> * This is a savefile, not a live capture file, so
> * never say it's in non-blocking mode.
> */
> return (0);
> }
> #ifndef WIN32
> fdflags = fcntl(p->fd, F_GETFL, 0);
> if (fdflags == -1) {
> snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "F_GETFL: %s",
> pcap_strerror(errno));
> return (-1);
> }
> if (fdflags & O_NONBLOCK)
> return (1);
> else
> return (0);
> #else
> return (p->nonblock);
> #endif
> }
>
> int
> pcap_setnonblock(pcap_t *p, int nonblock, char *errbuf)
> {
> #ifndef WIN32
> int fdflags;
> #else
> int newtimeout;
> #endif
>
> if (p->sf.rfile != NULL) {
> /*
> * This is a savefile, not a live capture file, so
> * ignore requests to put it in non-blocking mode.
> */
> return (0);
> }
> #ifndef WIN32
> fdflags = fcntl(p->fd, F_GETFL, 0);
> if (fdflags == -1) {
> snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "F_GETFL: %s",
> pcap_strerror(errno));
> return (-1);
> }
> if (nonblock)
> fdflags |= O_NONBLOCK;
> else
> fdflags &= ~O_NONBLOCK;
> if (fcntl(p->fd, F_SETFL, fdflags) == -1) {
> snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "F_SETFL: %s",
> pcap_strerror(errno));
> return (-1);
> }
> #else
> if (nonblock) {
> /*
> * Set the read timeout to -1 for non-blocking mode.
> */
> newtimeout = -1;
> } else {
> /*
> * Restore the timeout set when the device was opened.
> * (Note that this may be -1, in which case we're not
> * really leaving non-blocking mode.)
> */
> newtimeout = p->timeout;
> }
> if (!PacketSetReadTimeout(p->adapter, newtimeout)) {
> snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
> "PacketSetReadTimeout: %s", pcap_win32strerror());
> return (-1);
> }
> p->nonblock = (newtimeout == -1);
> #endif
> return (0);
> }
> -
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-
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