assert(!err);
return buf;
}
+
+/*
+ * Reverse-domain parsing and construction.
+ */
+
+int adns__make_reverse_domain(const struct sockaddr *sa, const char *zone,
+ char **buf_io, size_t bufsz,
+ char **buf_free_r) {
+ size_t req;
+ char *p;
+ unsigned c, y;
+ unsigned long aa;
+ const unsigned char *ap;
+ int i, j;
+
+ switch (sa->sa_family) {
+ AF_CASES(af);
+ af_inet:
+ req= 4 * 4;
+ if (!zone) zone= "in-addr.arpa";
+ break;
+ af_inet6:
+ req = 2 * 32;
+ if (!zone) zone= "ip6.arpa";
+ break;
+ default:
+ return ENOSYS;
+ }
+
+ req += strlen(zone) + 1;
+ if (req <= bufsz)
+ p= *buf_io;
+ else {
+ p= malloc(req); if (!p) return errno;
+ *buf_free_r = p;
+ }
+
+ *buf_io= p;
+ switch (sa->sa_family) {
+ AF_CASES(bf);
+ bf_inet:
+ aa= ntohl(CSIN(sa)->sin_addr.s_addr);
+ for (i=0; i<4; i++) {
+ p += sprintf(p, "%d", (int)(aa & 0xff));
+ *p++= '.';
+ aa >>= 8;
+ }
+ break;
+ bf_inet6:
+ ap= CSIN6(sa)->sin6_addr.s6_addr + 16;
+ for (i=0; i<16; i++) {
+ c= *--ap;
+ for (j=0; j<2; j++) {
+ y= c & 0xf;
+ *p++= (y < 10) ? y + '0' : y - 10 + 'a';
+ c >>= 4;
+ *p++= '.';
+ }
+ }
+ break;
+ default:
+ unknown_af(sa->sa_family);
+ }
+
+ strcpy(p, zone);
+ return 0;
+}
+
+
+static int inet_rev_parsecomp(const char *p, size_t n) {
+ int i= 0;
+ if (n > 3) return -1;
+
+ while (n--) {
+ if ('0' <= *p && *p <= '9') i= 10*i + *p++ - '0';
+ else return -1;
+ }
+ return i;
+}
+
+static void inet_rev_mkaddr(union gen_addr *addr, const byte *ipv) {
+ addr->v4.s_addr= htonl((ipv[3]<<24) | (ipv[2]<<16) |
+ (ipv[1]<<8) | (ipv[0]));
+}
+
+static int inet6_rev_parsecomp(const char *p, size_t n) {
+ if (n != 1) return -1;
+ else if ('0' <= *p && *p <= '9') return *p - '0';
+ else if ('a' <= *p && *p <= 'f') return *p - 'a' + 10;
+ else if ('A' <= *p && *p <= 'F') return *p - 'a' + 10;
+ else return -1;
+}
+
+static void inet6_rev_mkaddr(union gen_addr *addr, const byte *ipv) {
+ unsigned char *a= addr->v6.s6_addr;
+ int i;
+
+ for (i=0; i<16; i++)
+ a[i]= (ipv[31-2*i] << 4) | (ipv[30-2*i] << 0);
+}
+
+static const struct revparse_domain {
+ int af; /* address family */
+ int nrevlab; /* n of reverse-address labels */
+ adns_rrtype rrtype; /* forward-lookup type */
+
+ int (*rev_parsecomp)(const char *p, size_t n);
+ /* parse a single component from a label; return the integer value, or -1
+ * if it was unintelligible.
+ */
+
+ void (*rev_mkaddr)(union gen_addr *addr, const byte *ipv);
+ /* write out the parsed address from a vector of parsed components */
+
+ const char *const tail[3]; /* tail label names */
+} revparse_domains[NREVDOMAINS] = {
+ { AF_INET, 4, adns_r_a, inet_rev_parsecomp, inet_rev_mkaddr,
+ { DNS_INADDR_ARPA, 0 } },
+ { AF_INET6, 32, adns_r_aaaa, inet6_rev_parsecomp, inet6_rev_mkaddr,
+ { DNS_IP6_ARPA, 0 } },
+};
+
+#define REVDOMAIN_MAP(rps, labnum) \
+ ((labnum) ? (rps)->map : (1 << NREVDOMAINS) - 1)
+
+int adns__revparse_label(struct revparse_state *rps, int labnum,
+ const char *label, int lablen) {
+ unsigned f= REVDOMAIN_MAP(rps, labnum);
+ const struct revparse_domain *rpd;
+ const char *tp;
+ unsigned d;
+ int i, ac;
+
+ for (rpd=revparse_domains, i=0, d=1; i<NREVDOMAINS; rpd++, i++, d <<= 1) {
+ if (!(f & d)) continue;
+ if (labnum >= rpd->nrevlab) {
+ tp = rpd->tail[labnum - rpd->nrevlab];
+ if (!tp || strncmp(label, tp, lablen) != 0 || tp[lablen])
+ goto mismatch;
+ } else {
+ ac= rpd->rev_parsecomp(label, lablen);
+ if (ac < 0) goto mismatch;
+ assert(labnum < sizeof(rps->ipv[i]));
+ rps->ipv[i][labnum]= ac;
+ }
+ continue;
+
+ mismatch:
+ f &= ~d;
+ if (!f) return -1;
+ }
+
+ rps->map= f;
+ return 0;
+}
+
+int adns__revparse_done(struct revparse_state *rps, int nlabels,
+ adns_rrtype *rrtype_r, struct af_addr *addr_r) {
+ unsigned f= REVDOMAIN_MAP(rps, nlabels);
+ const struct revparse_domain *rpd;
+ unsigned d;
+ int i, found= -1;
+
+ for (rpd=revparse_domains, i=0, d=1; i<NREVDOMAINS; rpd++, i++, d <<= 1) {
+ if (!(f & d)) continue;
+ if (nlabels >= rpd->nrevlab && !rpd->tail[nlabels - rpd->nrevlab])
+ { found = i; continue; }
+ f &= ~d;
+ if (!f) return -1;
+ }
+ assert(found >= 0); assert(f == (1 << found));
+
+ rpd= &revparse_domains[found];
+ *rrtype_r= rpd->rrtype;
+ addr_r->af= rpd->af;
+ rpd->rev_mkaddr(&addr_r->addr, rps->ipv[found]);
+ return 0;
+}