#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/time.h>
#include "pktlib.h"
#include "lib.h"
#include "pcap.h"
struct pcap_file_header {
 pkt_uint32 magic;
#define PCAP_FILE_HEADER_MAGIC 0xA1B2C3D4
 pkt_uint16 version_major;
 pkt_uint16 version_minor;
#define PCAP_FILE_HEADER_VERSION_MAJOR 2
#define PCAP_FILE_HEADER_VERSION_MINOR 4
 pkt_int32 thiszone;
 pkt_uint32 sigfigs;
 pkt_uint32 snaplen;
#define PCAP_FILE_HEADER_SNAPLEN 0xFFFF
 pkt_uint32 linktype;
};
struct pcap_packet_header {
 struct {
 pkt_uint32 tv_sec;
 pkt_uint32 tv_usec;
 } ts;
 pkt_uint32 caplen;
 pkt_uint32 len;
};
typedef union {
 pkt_uint32 w;
 pkt_uint16 h[2];
 pkt_uint8 b[4];
} eword_t;
static pkt_uint32 read_ne32(pkt_uint32 val)
{
 return val;
}
static pkt_uint16 read_ne16(pkt_uint16 val)
{
 return val;
}
static pkt_uint32 read_le32(pkt_uint32 val)
{
 eword_t ew;
 ew.w = val;
 return (ew.b[3] << 24) &#124; (ew.b[2] << 16) &#124; (ew.b[1] << 8) &#124; ew.b[0]; } static pkt_uint32 read_be32(pkt_uint32 val) { eword_t ew; ew.w = val; return (ew.b[0] << 24) &#124; (ew.b[1] << 16) &#124; (ew.b[2] << 8) &#124; ew.b[3]; } static pkt_uint16 read_le16(pkt_uint16 val) { eword_t ew; ew.h[0] = val; return (ew.b[1] << 8) &#124; ew.b[0]; } static pkt_uint16 read_be16(pkt_uint16 val) { eword_t ew; ew.h[0] = val; return (ew.b[0] << 8) &#124; ew.b[1]; } typedef pkt_uint32 (*read_32_t)(pkt_uint32 val); typedef pkt_uint16 (*read_16_t)(pkt_uint16 val); static read_32_t read_32; static read_16_t read_16; static int read_file_header(FILE *fp, struct pcap_file_header *filehdr) { if (fread(filehdr, sizeof(*filehdr), 1, fp) == 0) return -1; if (filehdr->magic == PCAP_FILE_HEADER_MAGIC) {
 read_32 = read_ne32;
 read_16 = read_ne16;
 } else if (read_le32(filehdr->magic) == PCAP_FILE_HEADER_MAGIC) {
 read_32 = read_le32;
 read_16 = read_le16;
 } else if (read_be32(filehdr->magic) == PCAP_FILE_HEADER_MAGIC) {
 read_32 = read_be32;
 read_16 = read_be16;
 } else {
 pktlib_error_exit("Invalid magic number.\n");
 }
 filehdr->version_major = read_16(filehdr->version_major);
 filehdr->version_minor = read_16(filehdr->version_minor);
 filehdr->thiszone = read_32(filehdr->thiszone);
 filehdr->sigfigs = read_32(filehdr->sigfigs);
 filehdr->snaplen = read_32(filehdr->snaplen);
 filehdr->linktype = read_32(filehdr->linktype);
 return 0;
}
static int read_packet_header(FILE *fp, struct pcap_packet_header *pkthdr)
{
 if (fread(pkthdr, sizeof(*pkthdr), 1, fp) == 0)
 return -1;
 pkthdr->ts.tv_sec = read_32(pkthdr->ts.tv_sec);
 pkthdr->ts.tv_usec = read_32(pkthdr->ts.tv_usec);
 pkthdr->caplen = read_32(pkthdr->caplen);
 pkthdr->len = read_32(pkthdr->len);
 return 0;
}
static int write_file_header(FILE *fp, int linktype)
{
 struct pcap_file_header filehdr;
 memset(&filehdr, 0, sizeof(filehdr));
 filehdr.magic = PCAP_FILE_HEADER_MAGIC;
 filehdr.version_major = PCAP_FILE_HEADER_VERSION_MAJOR;
 filehdr.version_minor = PCAP_FILE_HEADER_VERSION_MINOR;
 filehdr.snaplen = PCAP_FILE_HEADER_SNAPLEN;
 filehdr.linktype = linktype;
 fwrite(&filehdr, sizeof(filehdr), 1, fp);
 return 0;
}
int pkt_pcap_read(FILE *fp, char *buffer, int size, int *linktypep,
		 int *origsizep, struct timeval *tm)
{
 static int init = 0;
 static struct pcap_file_header filehdr = { 0, 0, 0, 0, 0, 0, DLT_UNDEFINED };
 struct pcap_packet_header pkthdr;
 int capsize;
 pkt_uint32 family;
 if (!init) {
 if (read_file_header(fp, &filehdr) < 0) pktlib_error_exit("Cannot read file header.\n"); init++; } if (read_packet_header(fp, &pkthdr) < 0) return -1; capsize = pkthdr.caplen; if (capsize>= size)
 pktlib_error_exit("Out of buffer.\n");
 if (fread(buffer, capsize, 1, fp) == 0)
 pktlib_error_exit("Cannot read packet data.\n");
 if (filehdr.linktype == DLT_NULL) {
 if (capsize>= sizeof(family)) {
 memcpy(&family, buffer, sizeof(family));
 family = read_32(family);
 memcpy(buffer, &family, sizeof(family));
 }
 }
 if (linktypep) *linktypep = filehdr.linktype;
 if (origsizep) *origsizep = pkthdr.len;
 if (tm) {
 tm->tv_sec = pkthdr.ts.tv_sec;
 tm->tv_usec = pkthdr.ts.tv_usec;
 }
 return capsize;
}
int pkt_pcap_write(FILE *fp, char *buffer, int size, int linktype,
		 int origsize, struct timeval *tm)
{
 static int init = 0;
 struct pcap_packet_header pkthdr;
 static int oldlinktype = DLT_UNDEFINED;
 if (linktype == DLT_UNDEFINED)
 linktype = oldlinktype;
 if (!init) {
 write_file_header(fp, linktype);
 oldlinktype = linktype;
 init++;
 }
 if (linktype != oldlinktype)
 pktlib_error_exit("Link-layer type is changed.\n");
 pkthdr.ts.tv_sec = tm->tv_sec;
 pkthdr.ts.tv_usec = tm->tv_usec;
 pkthdr.caplen = size;
 pkthdr.len = origsize;
 if (fwrite(&pkthdr, sizeof(pkthdr), 1, fp) == 0)
 return -1;
 if (fwrite(buffer, size, 1, fp) == 0)
 return -1;
 fflush(fp);
 return size;
}
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