diff options
Diffstat (limited to 'netdissect.c')
| -rw-r--r-- | netdissect.c | 301 |
1 files changed, 301 insertions, 0 deletions
diff --git a/netdissect.c b/netdissect.c new file mode 100644 index 0000000..000d1ff --- /dev/null +++ b/netdissect.c @@ -0,0 +1,301 @@ +/* + * 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); +} |