Moving some of the BPF filtering code into base class.

This will allow packet sources that don't support BPF natively to
emulate the filtering via libpcap.

src/iosource/BPF_Program.cc

@@ -0,0 +1,131 @@
+// See the file "COPYING" in the main distribution directory for copyright.
+
+#include "config.h"
+
+#include "util.h"
+#include "BPF_Program.h"
+
+#ifdef DONT_HAVE_LIBPCAP_PCAP_FREECODE
+extern "C" {
+#include "pcap-int.h"
+
+int pcap_freecode(pcap_t* unused, struct bpf_program* program)
+	{
+	program->bf_len = 0;
+
+	if ( program->bf_insns )
+		{
+		free((char*) program->bf_insns);	// copied from libpcap
+		program->bf_insns = 0;
+		}
+
+	return 0;
+	}
+
+pcap_t* pcap_open_dead(int linktype, int snaplen)
+	{
+	pcap_t* p;
+
+	p = (pcap_t*) malloc(sizeof(*p));
+	if ( ! p )
+		return 0;
+
+	memset(p, 0, sizeof(*p));
+
+	p->fd = -1;
+	p->snapshot = snaplen;
+	p->linktype = linktype;
+
+	return p;
+	}
+
+int pcap_compile_nopcap(int snaplen_arg, int linktype_arg,
+			struct bpf_program* program, char* buf,
+			int optimize, bpf_u_int32 mask)
+	{
+	pcap_t* p;
+	int ret;
+
+	p = pcap_open_dead(linktype_arg, snaplen_arg);
+	if ( ! p )
+		return -1;
+
+	ret = pcap_compile(p, program, buf, optimize, mask);
+	pcap_close(p);
+
+	return ret;
+	}
+}
+#endif
+
+BPF_Program::BPF_Program() : m_compiled(), m_program()
+	{
+	}
+
+BPF_Program::~BPF_Program()
+	{
+	FreeCode();
+	}
+
+bool BPF_Program::Compile(pcap_t* pcap, const char* filter, uint32 netmask,
+			  char* errbuf, unsigned int errbuf_len, bool optimize)
+	{
+	if ( ! pcap )
+		return false;
+
+	FreeCode();
+
+	if ( pcap_compile(pcap, &m_program, (char *) filter, optimize, netmask) < 0 )
+		{
+		if ( errbuf )
+			safe_snprintf(errbuf, errbuf_len,
+				      "pcap_compile(%s): %s", filter,
+				      pcap_geterr(pcap));
+
+		return false;
+		}
+
+	m_compiled = true;
+
+	return true;
+	}
+
+bool BPF_Program::Compile(int snaplen, int linktype, const char* filter,
+				uint32 netmask, char* errbuf, bool optimize)
+	{
+	FreeCode();
+
+#ifdef LIBPCAP_PCAP_COMPILE_NOPCAP_HAS_ERROR_PARAMETER
+	char my_error[PCAP_ERRBUF_SIZE];
+
+	int err = pcap_compile_nopcap(snaplen, linktype, &m_program,
+				     (char *) filter, optimize, netmask, error);
+	if ( err < 0 && errbuf )
+		safe_strncpy(errbuf, my_errbuf, PCAP_ERRBUF_SIZE);
+#else
+	int err = pcap_compile_nopcap(snaplen, linktype, &m_program,
+				     (char*) filter, optimize, netmask);
+#endif
+	if ( err == 0 )
+		m_compiled = true;
+
+	return err == 0;
+	}
+
+bpf_program* BPF_Program::GetProgram()
+	{
+	return m_compiled ? &m_program : 0;
+	}
+
+void BPF_Program::FreeCode()
+	{
+	if ( m_compiled )
+		{
+#ifdef DONT_HAVE_LIBPCAP_PCAP_FREECODE
+		pcap_freecode(NULL, &m_program);
+#else
+		pcap_freecode(&m_program);
+#endif
+		m_compiled = false;
+		}
+	}