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// Copyright 2012 Google, Inc. All rights reserved.
// Copyright 2009-2011 Andreas Krennmair. All rights reserved.
//
// Use of this source code is governed by a BSD-style license
// that can be found in the LICENSE file in the root of the source
// tree.
//
// +build !windows
package pcap
/*
#include <stdlib.h>
#include <pcap.h>
// pcap_wait returns when the next packet is available or the timeout expires.
// Since it uses pcap_get_selectable_fd, it will not work in Windows.
int pcap_wait(pcap_t *p, int usec) {
fd_set fds;
int fd;
struct timeval tv;
fd = pcap_get_selectable_fd(p);
if(fd < 0) {
return fd;
}
FD_ZERO(&fds);
FD_SET(fd, &fds);
tv.tv_sec = 0;
tv.tv_usec = usec;
if(usec != 0) {
return select(fd+1, &fds, NULL, NULL, &tv);
}
// block indefinitely if no timeout provided
return select(fd+1, &fds, NULL, NULL, NULL);
}
*/
import "C"
import (
"errors"
"unsafe"
)
func (p *Handle) openLive() error {
buf := (*C.char)(C.calloc(errorBufferSize, 1))
defer C.free(unsafe.Pointer(buf))
// Change the device to non-blocking, we'll use pcap_wait to wait until the
// handle is ready to read.
if v := C.pcap_setnonblock(p.cptr, 1, buf); v == -1 {
return errors.New(C.GoString(buf))
}
return nil
}
// waitForPacket waits for a packet or for the timeout to expire.
func (p *Handle) waitForPacket() {
// need to wait less than the read timeout according to pcap documentation.
// timeoutMillis rounds up to at least one millisecond so we can safely
// subtract up to a millisecond.
usec := timeoutMillis(p.timeout) * 1000
usec -= 100
C.pcap_wait(p.cptr, usec)
}
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