diff options
Diffstat (limited to 'netdissect.c')
| -rw-r--r-- | netdissect.c | 159 |
1 files changed, 157 insertions, 2 deletions
diff --git a/netdissect.c b/netdissect.c index 0215c83b7f23..000d1ffce8c2 100644 --- a/netdissect.c +++ b/netdissect.c @@ -23,13 +23,14 @@ */ #ifdef HAVE_CONFIG_H -#include "config.h" +#include <config.h> #endif -#include <netdissect-stdinc.h> +#include "netdissect-stdinc.h" #include "netdissect.h" #include <string.h> #include <stdio.h> +#include <stdlib.h> #ifdef USE_LIBSMI #include <smi.h> @@ -144,3 +145,157 @@ nd_smi_version_string(void) 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); +} |