CDN_DNS/radix/radix.c

#include "radix.h"

#define GET_BIT(key, bit) ( ( key.s[ bit / 16 ] & (1u << (15 - bit % 16)) ) != 0 )

radix_node_t create_node(ipv6_t key, unsigned end_bit, unsigned rule) {
    radix_node_t ret = calloc(1, sizeof(struct radix_node));
    ret->_ip = key;
    ret->_ip_end_bit = end_bit;
    ret->_rule_valid = VALID_RULE;
    ret->_rule = rule;
    return ret;
}

static radix_node_t clone_node(radix_node_t n) {
    radix_node_t ret = calloc(1, sizeof(struct radix_node));
    memcpy(ret, n, sizeof(struct radix_node));
    return ret;
}

static void split_node(radix_node_t n, unsigned bit) {
    radix_node_t tmp = clone_node(n);
    n->_ip_end_bit = bit;
    n->_l = n->_r = tmp;
    n->_rule_valid = INVALID_RULE;
}

radix_holder_t create_holder() {
    radix_holder_t ret = calloc(1, sizeof(struct radix_holder));
    return ret;
}

int destory_holder(struct radix_holder* t) {
    destory_node(t->_root);
    free(t);
    return 1;
}

int destory_node(struct radix_node* n) {
    int ret = 0;
    if (!n) return ret;
    ret = destory_node(n->_l) + destory_node(n->_r);
    free(n);
    return ret;
}

int radix_insert(radix_holder_t t, ipv6_t key, int val, int mask) {
    unsigned char b;
    int ibit;
    radix_node_t node = t->_root;
    radix_node_t* next = &t->_root;

    if (!t->_root) {
        t->_root = create_node(key, mask, val);
        return t->_size = 1;
    }

    for (ibit = 0; ibit < mask; ++ibit) {
        b = GET_BIT(key, ibit);
        if (ibit >= node->_ip_end_bit) {   /* node key ends */
            next = b ? &node->_l : &node->_r;

            if (!*next) {
                *next = create_node(key, mask, val);
                ++t->_size;
                return 1;
            }

            node = *next;
            continue;
        }

        if (b == GET_BIT(node->_ip, ibit)) /* bit match */
            continue;
        
        next = b ? &node->_l : &node->_r;
        if (*next && ibit == mask - 1) {   /* last bit mismatch */
            node = *next;
            continue;
        } 
        
        split_node(node, ibit);            /* split node */
        *next = create_node(key, mask, val);
        ++t->_size;
        return 1;
    }
    
    /* exact match */
    if (node->_rule_valid && node->_ip_end_bit == mask) {
        printf("WARNING: conflicting rule %x:%x:%x:%x:%x:%x:%x:%x", 
            key.s[0], key.s[1], key.s[2], key.s[3],
            key.s[4], key.s[5], key.s[6], key.s[7]);
        
        printf("/%d %d\n", mask, val);
        return 0;
    }

    /* match with lower mask */
    if (node->_rule_valid) {
        split_node(node, ibit);

        b = GET_BIT(node->_ip, ibit + 1);
        next = b ? &node->_r : &node->_l;
        *next = NULL;
    }

    node->_rule_valid = VALID_RULE;
    node->_rule = val;
    return 1;
}

int radix_search(radix_holder_t t, ipv6_t key) {
    unsigned char b;
    int ret = INVALID_RULE;
    radix_node_t iter = t->_root;
    int ibit = 0;
    if (!iter)
        return INVALID_RULE;
        

    for (;ibit < 128; ++ibit) {
        b = GET_BIT(key, ibit);
        if (ibit < iter->_ip_end_bit &&
            b == GET_BIT(iter->_ip, ibit))
            continue;
        
        if (ibit == iter->_ip_end_bit) /* set result if full match */
            ret = iter->_rule_valid ? iter->_rule : ret;
        
        iter = b ? iter->_l : iter->_r;
        if (!iter)
            return ret;
    }
    return ret;
}



/*--------------------------------------------------------------------------------*/
/*                             TESTING                                            */
/*--------------------------------------------------------------------------------*/
#include <assert.h>

#define RULES_FILE "../data/routing-data"
#define TEST_FILE "../data/test-data"
#define TEST_ROWS 5527
#define READ_MODE "r"

int parse_line(ipv6_t* key, int* val, int* mask, FILE* f) { /*! assumes only good input */
    memset(key, 0, sizeof(ipv6_t));

    fscanf(f, "%hx:%hx:%hx:%hx:%hx:%hx:%hx:%hx", 
        &key->s[0], &key->s[1], &key->s[2], &key->s[3],
        &key->s[4], &key->s[5], &key->s[6], &key->s[7]);

    if (feof(f)) return 0; /* ends with newline */
    while (fgetc(f) != '/');
    
    fscanf(f, "%d %d", mask, val);
    return !feof(f);
}

int load_input(radix_holder_t t) {
    int val;
    int mask;
    ipv6_t key;
    FILE* f;
    int cnt = 0;
    
    if (!(f = fopen(RULES_FILE, READ_MODE))) {
        puts("cant open input file");
        exit(1);
    }
    
    while (parse_line(&key, &val, &mask, f)) {
        cnt += radix_insert(t, key, val, mask);
    }
    fclose(f);
    return cnt;
}

int load_tests(ipv6_t** rips, int** rref) {
    ipv6_t* ips;
    int* ref;
    int row;
    FILE* f;

    if (!(f = fopen( TEST_FILE, READ_MODE ))) {
        puts("cant open test file");
        exit(1);
    }

    ips = calloc( TEST_ROWS, sizeof(ipv6_t) );
    ref = calloc( TEST_ROWS, sizeof(int) );

    for (row = 0; row < TEST_ROWS; ++ row) {
        fscanf(f, "%hx:%hx:%hx:%hx:%hx:%hx:%hx:%hx", 
            &ips[row].s[0], &ips[row].s[1], &ips[row].s[2], &ips[row].s[3],
            &ips[row].s[4], &ips[row].s[5], &ips[row].s[6], &ips[row].s[7]);
        

        while (fgetc(f) != ' ');
        fscanf(f, "%d", &(ref[row]));
    }
    fclose(f);

    *rips = ips;
    *rref = ref;
    return TEST_ROWS;
}

int fire_tests(radix_holder_t t, ipv6_t* ips, int* ref, int num_tests ) {
    int row;
    int wrong = 0;

    for (row = 0; row < TEST_ROWS; ++ row) {
        if (radix_search(t, ips[row]) !=  ref[row]) {
            printf("ref: %d got: %d @ %d\n", ref[row], radix_search(t, ips[row]), row );
        ++wrong;
        }
    }

    free(ips);
    free(ref);
    return wrong;
}

int main() {
    ipv6_t* ips;
    int* ref;    

    radix_holder_t t = create_holder();
    
    printf("Loaded %d rules\n", load_input(t) );
    printf("Loaded %d tests\n", load_tests(&ips, &ref) );
    printf("%d tests wrong\n", fire_tests(t, ips, ref, TEST_ROWS) );

    destory_holder(t);
    return 0;
}