ipipqx.c

//
// Created by yue on 16-5-27.
//

#include "ipip.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

typedef unsigned char byte;
typedef unsigned int uint;
#define B2IL(b) (((b)[0] & 0xFF) | (((b)[1] << 8) & 0xFF00) | (((b)[2] << 16) & 0xFF0000) | (((b)[3] << 24) & 0xFF000000))
#define B2IU(b) (((b)[3] & 0xFF) | (((b)[2] << 8) & 0xFF00) | (((b)[1] << 16) & 0xFF0000) | (((b)[0] << 24) & 0xFF000000))

struct {
    byte *data;
    byte *index;
    uint *flag;
    uint offset;
} ipip;

int destroy() {
    if (!ipip.offset) {
        return 0;
    }
    free(ipip.flag);
    free(ipip.index);
    free(ipip.data);
    ipip.offset = 0;
    return 0;
}

int init(const char *ipdb) {
    if (ipip.offset) {
        return 0;
    }
    FILE *file = fopen(ipdb, "rb");
    fseek(file, 0, SEEK_END);
    long size = ftell(file);
    fseek(file, 0, SEEK_SET);

    ipip.data = (byte *) malloc(size * sizeof(byte));
    fread(ipip.data, sizeof(byte), (size_t) size, file);

    fclose(file);

    uint indexLength = B2IU(ipip.data);

    ipip.index = (byte *) malloc(indexLength * sizeof(byte));
    memcpy(ipip.index, ipip.data + 4, indexLength);

    ipip.offset = indexLength;

    ipip.flag = (uint *) malloc(65536 * sizeof(uint));
    memcpy(ipip.flag, ipip.index, 65536 * sizeof(uint));

    return 0;
}

int find(const char *ip, char *result) {
    uint ips[4];
    int num = sscanf(ip, "%d.%d.%d.%d", &ips[0], &ips[1], &ips[2], &ips[3]);
    if (num == 4) {
        uint ip_prefix_value = ips[0] * 256 + ips[1];
        uint ip2long_value = B2IU(ips);
        uint start = ipip.flag[ip_prefix_value];
        uint max_comp_len = ipip.offset - 262148;
        int index_offset = -1;
        int index_length = -1;
        for (start = start * 13 + 262144; start < max_comp_len; start += 13) {
            if (B2IU(ipip.index + start) <= ip2long_value) {
                if (B2IU(ipip.index + start + 4) >= ip2long_value) {
                    index_offset = B2IL(ipip.index + start + 8) & 0x00FFFFFF;
                    index_length = 0xff & ipip.index[start + 12];
                    break;
                }
            } else {
                break;
            }
        }
        if (index_offset == -1 && index_length == -1) {
            return 0;
        }
        memcpy(result, ipip.data + ipip.offset + index_offset - 262144, (size_t) index_length);
        result[index_length] = '\0';
        return 1;
    }
    return 0;
}