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+/*
+ * Copyright (c) 1988-1997
+ * The Regents of the University of California. All rights reserved.
+ *
+ * Copyright (c) 1998-2012 Michael Richardson <mcr@tcpdump.org>
+ * The TCPDUMP project
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that: (1) source code distributions
+ * retain the above copyright notice and this paragraph in its entirety, (2)
+ * distributions including binary code include the above copyright notice and
+ * this paragraph in its entirety in the documentation or other materials
+ * provided with the distribution, and (3) all advertising materials mentioning
+ * features or use of this software display the following acknowledgement:
+ * ``This product includes software developed by the University of California,
+ * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
+ * the University nor the names of its contributors may be used to endorse
+ * or promote products derived from this software without specific prior
+ * written permission.
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include "netdissect-stdinc.h"
+#include "netdissect.h"
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#ifdef USE_LIBSMI
+#include <smi.h>
+#endif
+
+/*
+ * Initialize anything that must be initialized before dissecting
+ * packets.
+ *
+ * This should be called at the beginning of the program; it does
+ * not need to be called, and should not be called, for every
+ * netdissect_options structure.
+ */
+int
+nd_init(char *errbuf, size_t errbuf_size)
+{
+#ifdef _WIN32
+ WORD wVersionRequested;
+ WSADATA wsaData;
+ int err;
+
+ /*
+ * Request Winsock 2.2; we expect Winsock 2.
+ */
+ wVersionRequested = MAKEWORD(2, 2);
+ err = WSAStartup(wVersionRequested, &wsaData);
+ if (err != 0) {
+ strlcpy(errbuf, "Attempting to initialize Winsock failed",
+ errbuf_size);
+ return (-1);
+ }
+#endif /* _WIN32 */
+
+#ifdef USE_LIBSMI
+ /*
+ * XXX - should we just fail if this fails? Some of the
+ * libsmi calls may fail.
+ */
+ smiInit("tcpdump");
+#endif
+
+ /*
+ * Clears the error buffer, and uses it so we don't get
+ * "unused argument" warnings at compile time.
+ */
+ strlcpy(errbuf, "", errbuf_size);
+ return (0);
+}
+
+/*
+ * Clean up anything that ndo_init() did.
+ */
+void
+nd_cleanup(void)
+{
+#ifdef USE_LIBSMI
+ /*
+ * This appears, in libsmi 0.4.8, to do nothing if smiInit()
+ * wasn't done or failed, so we call it unconditionally.
+ */
+ smiExit();
+#endif
+
+#ifdef _WIN32
+ /*
+ * Undo the WSAStartup() call above.
+ */
+ WSACleanup();
+#endif
+}
+
+int
+nd_have_smi_support(void)
+{
+#ifdef USE_LIBSMI
+ return (1);
+#else
+ return (0);
+#endif
+}
+
+/*
+ * Indicates whether an SMI module has been loaded, so that we can use
+ * libsmi to translate OIDs.
+ */
+int nd_smi_module_loaded;
+
+int
+nd_load_smi_module(const char *module, char *errbuf, size_t errbuf_size)
+{
+#ifdef USE_LIBSMI
+ if (smiLoadModule(module) == 0) {
+ snprintf(errbuf, errbuf_size, "could not load MIB module %s",
+ module);
+ return (-1);
+ }
+ nd_smi_module_loaded = 1;
+ return (0);
+#else
+ snprintf(errbuf, errbuf_size, "MIB module %s not loaded: no libsmi support",
+ module);
+ return (-1);
+#endif
+}
+
+const char *
+nd_smi_version_string(void)
+{
+#ifdef USE_LIBSMI
+ return (smi_version_string);
+#else
+ return (NULL);
+#endif
+}
+
+
+int
+nd_push_buffer(netdissect_options *ndo, u_char *new_buffer,
+ const u_char *new_packetp, const u_int newlen)
+{
+ struct netdissect_saved_packet_info *ndspi;
+
+ ndspi = (struct netdissect_saved_packet_info *)malloc(sizeof(struct netdissect_saved_packet_info));
+ if (ndspi == NULL)
+ return (0); /* fail */
+ ndspi->ndspi_buffer = new_buffer;
+ ndspi->ndspi_packetp = ndo->ndo_packetp;
+ ndspi->ndspi_snapend = ndo->ndo_snapend;
+ ndspi->ndspi_prev = ndo->ndo_packet_info_stack;
+
+ ndo->ndo_packetp = new_packetp;
+ ndo->ndo_snapend = new_packetp + newlen;
+ ndo->ndo_packet_info_stack = ndspi;
+
+ return (1); /* success */
+}
+
+
+/*
+ * In a given netdissect_options structure:
+ *
+ * push the current packet information onto the packet information
+ * stack;
+ *
+ * given a pointer into the packet and a length past that point in
+ * the packet, calculate a new snapshot end that's at the lower
+ * of the current snapshot end and that point in the packet;
+ *
+ * set the snapshot end to that new value.
+ */
+int
+nd_push_snaplen(netdissect_options *ndo, const u_char *bp, const u_int newlen)
+{
+ struct netdissect_saved_packet_info *ndspi;
+ u_int snaplen_remaining;
+
+ ndspi = (struct netdissect_saved_packet_info *)malloc(sizeof(struct netdissect_saved_packet_info));
+ if (ndspi == NULL)
+ return (0); /* fail */
+ ndspi->ndspi_buffer = NULL; /* no new buffer */
+ ndspi->ndspi_packetp = ndo->ndo_packetp;
+ ndspi->ndspi_snapend = ndo->ndo_snapend;
+ ndspi->ndspi_prev = ndo->ndo_packet_info_stack;
+
+ /*
+ * Push the saved previous data onto the stack.
+ */
+ ndo->ndo_packet_info_stack = ndspi;
+
+ /*
+ * Find out how many bytes remain after the current snapend.
+ *
+ * We're restricted to packets with at most UINT_MAX bytes;
+ * cast the result to u_int, so that we don't get truncation
+ * warnings on LP64 and LLP64 platforms. (ptrdiff_t is
+ * signed and we want an unsigned difference; the pointer
+ * should at most be equal to snapend, and must *never*
+ * be past snapend.)
+ */
+ snaplen_remaining = (u_int)(ndo->ndo_snapend - bp);
+
+ /*
+ * If the new snapend is smaller than the one calculated
+ * above, set the snapend to that value, otherwise leave
+ * it unchanged.
+ */
+ if (newlen <= snaplen_remaining) {
+ /* Snapend isn't past the previous snapend */
+ ndo->ndo_snapend = bp + newlen;
+ }
+
+ return (1); /* success */
+}
+
+/*
+ * In a given netdissect_options structure:
+ *
+ * given a pointer into the packet and a length past that point in
+ * the packet, calculate a new snapshot end that's at the lower
+ * of the previous snapshot end - or, if there is no previous
+ * snapshot end, the current snapshot end - and that point in the
+ * packet;
+ *
+ * set the snapshot end to that new value.
+ *
+ * This is to change the current snapshot end. This may increase the
+ * snapshot end, as it may be used, for example, for a Jumbo Payload
+ * option in IPv6. It must not increase it past the snapshot length
+ * atop which the current one was pushed, however.
+ */
+void
+nd_change_snaplen(netdissect_options *ndo, const u_char *bp, const u_int newlen)
+{
+ struct netdissect_saved_packet_info *ndspi;
+ const u_char *previous_snapend;
+ u_int snaplen_remaining;
+
+ ndspi = ndo->ndo_packet_info_stack;
+ if (ndspi->ndspi_prev != NULL)
+ previous_snapend = ndspi->ndspi_prev->ndspi_snapend;
+ else
+ previous_snapend = ndo->ndo_snapend;
+
+ /*
+ * Find out how many bytes remain after the previous
+ * snapend - or, if there is no previous snapend, after
+ * the current snapend.
+ *
+ * We're restricted to packets with at most UINT_MAX bytes;
+ * cast the result to u_int, so that we don't get truncation
+ * warnings on LP64 and LLP64 platforms. (ptrdiff_t is
+ * signed and we want an unsigned difference; the pointer
+ * should at most be equal to snapend, and must *never*
+ * be past snapend.)
+ */
+ snaplen_remaining = (u_int)(previous_snapend - bp);
+
+ /*
+ * If the new snapend is smaller than the one calculated
+ * above, set the snapend to that value, otherwise leave
+ * it unchanged.
+ */
+ if (newlen <= snaplen_remaining) {
+ /* Snapend isn't past the previous snapend */
+ ndo->ndo_snapend = bp + newlen;
+ }
+}
+
+void
+nd_pop_packet_info(netdissect_options *ndo)
+{
+ struct netdissect_saved_packet_info *ndspi;
+
+ ndspi = ndo->ndo_packet_info_stack;
+ ndo->ndo_packetp = ndspi->ndspi_packetp;
+ ndo->ndo_snapend = ndspi->ndspi_snapend;
+ ndo->ndo_packet_info_stack = ndspi->ndspi_prev;
+
+ free(ndspi->ndspi_buffer);
+ free(ndspi);
+}
+
+void
+nd_pop_all_packet_info(netdissect_options *ndo)
+{
+ while (ndo->ndo_packet_info_stack != NULL)
+ nd_pop_packet_info(ndo);
+}