kopia lustrzana https://github.com/F5OEO/tstools
199 wiersze
3.8 KiB
C
199 wiersze
3.8 KiB
C
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/* pcap.c */
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/*
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* Read pcap files.
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*
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* <rrw@kynesim.co.uk> 2008-09-04
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*/
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/* Both of these return 1 on success, 0 on EOF, <0 on error */
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#include "pcap.h"
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#include "misc_fns.h"
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static int pcap_read_header(PCAP_reader_p ctx, pcap_hdr_t *out_hdr);
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static int pcap_read_pktheader(PCAP_reader_p ctx, pcaprec_hdr_t *out_hdr);
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int pcap_open(PCAP_reader_p *ctx_p, pcap_hdr_t *out_hdr,
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const char *filename)
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{
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FILE *fptr = (filename ? fopen(filename, "rb") : stdin);
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PCAP_reader_p ctx;
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int rv;
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(*ctx_p) = NULL;
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if (!fptr)
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{
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// Couldn't open the file.
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return -1;
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}
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ctx = (PCAP_reader_p)malloc(SIZEOF_PCAP_READER);
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if (!ctx)
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{
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fclose(fptr);
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// Out of memory.
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return -2;
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}
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ctx->file = fptr;
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rv = pcap_read_header(ctx, out_hdr);
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if (rv != 1)
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{
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// Header read failed.
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fclose(ctx->file);
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free(ctx);
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return -4;
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}
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(*ctx_p) = ctx;
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return 0;
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}
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int pcap_read_next(PCAP_reader_p ctx, pcaprec_hdr_t *out_hdr,
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uint8_t **out_data,
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uint32_t *out_len)
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{
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int rv;
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(*out_data) = NULL; (*out_len) = 0;
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rv = pcap_read_pktheader(ctx, out_hdr);
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if (rv != 1) { return rv; }
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// Otherwise we now know how long our packet is ..
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(*out_data) = (uint8_t *)malloc(out_hdr->incl_len);
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if (!(*out_data))
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{
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// Out of memory.
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return -3;
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}
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(*out_len) = out_hdr->incl_len;
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rv = fread((*out_data), (*out_len), 1, ctx->file);
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if (rv != 1)
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{
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free(*out_data); (*out_data) = NULL;
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*out_len = 0;
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if (feof(ctx->file))
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{
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// Ah. EOF.
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return 0;
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}
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else
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{
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// Error. Curses.
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return rv;
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}
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}
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else if (rv == 1)
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{
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// Gotcha.
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return 1;
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}
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return 0;
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}
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static int pcap_read_header(PCAP_reader_p ctx, pcap_hdr_t *hdr)
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{
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uint8_t hdr_val[SIZEOF_PCAP_HDR_ON_DISC];
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int rv;
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rv = fread(&hdr_val[0], SIZEOF_PCAP_HDR_ON_DISC, 1, ctx->file);
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if (rv != 1)
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{
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if (feof(ctx->file))
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{
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return 0;
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}
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else
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{
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return PCAP_ERR_FILE_READ;
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}
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}
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/* The magic number is 0xa1b2c3d4. If the writing
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* machine was BE, the first byte will be a1 else d4
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*/
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if (hdr_val[0] == 0xa1)
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{
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// Big endian.
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ctx->is_be = 1;
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}
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else if (hdr_val[0] == 0xd4)
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{
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// Little endian.
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ctx->is_be = 0;
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}
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else
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{
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return PCAP_ERR_INVALID_MAGIC;
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}
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hdr->magic_number = (ctx->is_be ? uint_32_be(&hdr_val[0]) :
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uint_32_le(&hdr_val[0]));
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if (hdr->magic_number != 0xa1b2c3d4)
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{
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return PCAP_ERR_INVALID_MAGIC;
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}
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hdr->version_major = (ctx->is_be ? uint_16_be(&hdr_val[4]) :
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uint_16_le(&hdr_val[4]));
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hdr->version_minor = (ctx->is_be ? uint_16_be(&hdr_val[6]) :
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uint_16_le(&hdr_val[6]));
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hdr->thiszone = (int32_t)(ctx->is_be ? uint_32_be(&hdr_val[8]) :
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uint_32_le(&hdr_val[8]));
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hdr->sigfigs = (ctx->is_be ? uint_32_be(&hdr_val[12]) :
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uint_32_le(&hdr_val[12]));
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hdr->snaplen = (ctx->is_be ? uint_32_be(&hdr_val[16]) :
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uint_32_le(&hdr_val[16]));
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hdr->network = (ctx->is_be ? uint_32_be(&hdr_val[20]) :
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uint_32_le(&hdr_val[20]));
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return 1;
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}
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static int pcap_read_pktheader(PCAP_reader_p ctx, pcaprec_hdr_t *hdr)
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{
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uint8_t hdr_val[SIZEOF_PCAPREC_HDR_ON_DISC];
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int rv;
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rv = fread(&hdr_val[0], SIZEOF_PCAPREC_HDR_ON_DISC, 1, ctx->file);
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if (rv != 1)
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{
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if (feof(ctx->file))
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{
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return 0;
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}
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else
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{
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return PCAP_ERR_FILE_READ;
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}
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}
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hdr->ts_sec = (ctx->is_be ? uint_32_be(&hdr_val[0]) :
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uint_32_le(&hdr_val[0]));
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hdr->ts_usec = (ctx->is_be ? uint_32_be(&hdr_val[4]) :
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uint_32_le(&hdr_val[4]));
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hdr->incl_len = (ctx->is_be ? uint_32_be(&hdr_val[8]) :
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uint_32_le(&hdr_val[8]));
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hdr->orig_len = (ctx->is_be ? uint_32_be(&hdr_val[12]) :
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uint_32_le(&hdr_val[12]));
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return 1;
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}
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/* End file */
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