spf.c

/*
 * Part of DNS zone file validator `validns`.
 *
 * Copyright 2011-2014 Anton Berezin <tobez@tobez.org>
 * Modified BSD license.
 * (See LICENSE file in the distribution.)
 *
 */
#include <sys/types.h>
#include <stdio.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#include "common.h"
#include "textparse.h"
#include "mempool.h"
#include "carp.h"
#include "rr.h"

/* XXX
 * We need to add the following spf-specific policy checks:
 *  - record not too long (DNS name + length of SPF+TXT < 450) - rfc4408, 3.1.4
 *  - record should match /^v=spf1( |$)/  - rfc4408, 4.5
 *  - maybe check for other syntax features
 *  - there should be an identical TXT record - rfc4408, 3.1.1
 *  - there should only be one SPF per DNS name - rfc4408, 4.5
 */

static struct rr *spf_parse(char *name, long ttl, int type, char *s)
{
    struct rr_spf *rr;
    struct binary_data spf[20];
    int i;

    i = 0;
    while (*s) {
        if (i >= 20)
            return bitch("program limit: too many SPF text segments");
        spf[i] = extract_text(&s, "SPF text segment");
        if (spf[i].length < 0)
            return NULL;
        if (spf[i].length > 255)
            return bitch("SPF segment too long");
        i++;
    }
    if (i == 0)
        return bitch("empty text record");

    rr = getmem(sizeof(*rr) + sizeof(struct binary_data) * (i-1));
    rr->count = i;
    for (i = 0; i < rr->count; i++) {
        rr->spf[i] = spf[i];
    }

    return store_record(type, name, ttl, rr);
}

static char* spf_human(struct rr *rrv)
{
    RRCAST(spf);
    char ss[1024];
    int i;
    char *s = ss;
    int l;

    for (i = 0; i < rr->count; i++) {
        l = snprintf(s, 1024-(s-ss), "\"%s\" ", rr->spf[i].data);
        s += l;
    }
    return quickstrdup_temp(ss);
}

static struct binary_data spf_wirerdata(struct rr *rrv)
{
    RRCAST(spf);
    struct binary_data r, t;
    int i;

    r = bad_binary_data();
    t.length = 0;
    t.data = NULL;
    for (i = 0; i < rr->count; i++) {
        r = compose_binary_data("db", 1, t, rr->spf[i]);
        t = r;
    }
    return r;
}

struct rr_methods spf_methods = { spf_parse, spf_human, spf_wirerdata, NULL, NULL };