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Description: Use root.hints from dns-root-data
This patch enables loading DNS root server hints as offered by
package dns-root-data (or using equivalent paths under /usr/local) if
they are available. Otherwise the compiled-in defaults are used.
.
Setting BELLE_SIP_NO_SYS_ROOT_HINTS in the environment disables this
feature. Setting BELLE_SIP_LOG_ROOT_HINTS in the environment logs
the loaded root server definitions to stderr which can be used to
reveal discrepancies.
.
The code is short and easy to understand, though not very efficient,
but since it runs only once at start-up that should not matter much.
Bug-Debian: https://bugs.debian.org/760467
Author: Dennis Filder <d.filder@web.de>
Last-Update: 2021-12-03
Forwarded: not-needed
--- a/src/dns/dns.c
+++ b/src/dns/dns.c
@@ -5856,11 +5856,120 @@
return 0;
} /* dns_hints_local() */
+struct rootserver {
+ int af;
+ char addr[INET6_ADDRSTRLEN];
+};
+
+static int learn_system_root_servers(struct rootserver **servers_pp, size_t *nentries) {
+ static const char *Hint_paths[] = {
+ "/usr/local/share/dns/root.hints",
+ "/usr/share/dns/root.hints",
+ NULL
+ };
+
+ FILE *fp;
+ char *hintfile;
+ int addrfam = AF_INET, linecount=0, stillgood = 1;
+ struct rootserver *servers = NULL;
+ size_t nservers = 0;
+
+ for (hintfile = (char*) Hint_paths[0]; hintfile; hintfile++) {
+ if ((fp = fopen(hintfile, "r")) != NULL)
+ break;
+ }
+
+ if (fp == NULL) {
+ fprintf(stderr, "Error: parse-root-hints: could not open any root.hints file. Aborting.\n");
+ return -1;
+ }
+
+ do {
+ size_t linelen=0;
+ char *line = NULL;
+ errno = 0;
+ ssize_t res = getline(&line, &linelen, fp);
+
+ if (res == -1) {
+ if (errno != 0) /* something irrecoverable happened */
+ stillgood = 0;
+ break;
+ }
+ linecount++;
+
+ if (line) {
+ if ( ( line[0] >= 'A' && line[0] <= 'Z' )
+ && linelen >= strlen("*.ROOT-SERVERS.NET.")
+ && memcmp(line+1, ".ROOT-SERVERS.NET.", strlen(".ROOT-SERVERS.NET.")) == 0) {
+ char *rr = NULL, *ipaddr = NULL;
+ int ret = sscanf(line, " %*s %*s %ms %ms ", &rr, &ipaddr);
+
+ if (ret == 2) {
+ if (rr && strlen(rr) == strlen("AAAA") && strcmp(rr, "AAAA") == 0) {
+ addrfam = AF_INET6;
+ } else if (rr && strlen(rr) == strlen("A") && strcmp(rr, "A") == 0) {
+ addrfam = AF_INET;
+ } else {
+ fprintf(stderr, "Warning: bogus resource record %s in %s, line %d. Skipping.\n", rr, hintfile, linecount);
+ goto free_fields;
+ }
+
+ if (ipaddr && strlen(ipaddr) >= 1) {
+ /* we got a new server definition, add it! */
+ nservers++;
+
+ struct rootserver *p = realloc(servers, sizeof(struct rootserver) * nservers);
+ if (p == NULL) {
+ if (servers)
+ free(servers);
+ nservers = 0;
+ servers = NULL;
+ fprintf(stderr, "Error: out of memory. Aborting.\n");
+ stillgood = 0;
+ goto free_fields;
+ }
+ servers = p;
+
+ memset(&servers[nservers-1], 0, sizeof(struct rootserver));
+ servers[nservers-1].af = addrfam;
+ strncpy(servers[nservers-1].addr, ipaddr, INET6_ADDRSTRLEN);
+ servers[nservers-1].addr[INET6_ADDRSTRLEN-1] = '\0';
+ }
+
+ }
+ free_fields:
+ if (rr)
+ free(rr);
+ if (ipaddr)
+ free(ipaddr);
+ }
+
+ free(line);
+ line = NULL;
+ linelen = 0;
+ res = 0;
+ if (stillgood)
+ continue;
+ } else {
+ break;
+ }
+
+ } while (1);
+
+ if (fp)
+ fclose(fp);
+
+ if (stillgood && nservers >= 1) {
+ *servers_pp = servers;
+ *nentries = nservers;
+ return 0;
+ }
+ return -1;
+} /* learn_system_root_servers() */
+
struct dns_hints *dns_hints_root(struct dns_resolv_conf *resconf, int *error_) {
- static const struct {
- int af;
- char addr[INET6_ADDRSTRLEN];
- } root_hints[] = {
+ static const struct rootserver
+ fallback_root_hints[] = {
{AF_INET, "198.41.0.4"}, /* A.ROOT-SERVERS.NET. */
{AF_INET6, "2001:503:ba3e::2:30"}, /* A.ROOT-SERVERS.NET. */
{AF_INET, "192.228.79.201"}, /* B.ROOT-SERVERS.NET. */
@@ -5887,6 +5996,16 @@
{AF_INET, "202.12.27.33"}, /* M.ROOT-SERVERS.NET. */
{AF_INET6, "2001:DC3::35"}, /* M.ROOT-SERVERS.NET. */
};
+ struct rootserver *sys_root_hints, *root_hints;
+ size_t nsys_root_hints, nroot_hints, nfallback_root_hints = lengthof(fallback_root_hints);
+ int ret = learn_system_root_servers(&sys_root_hints, &nsys_root_hints);
+ if (ret == -1 || getenv("BELLE_SIP_NO_SYS_ROOT_HINTS")) {
+ root_hints = (struct rootserver *)&fallback_root_hints[0];
+ nroot_hints = nfallback_root_hints;
+ } else {
+ root_hints = sys_root_hints;
+ nroot_hints = nsys_root_hints;
+ }
struct dns_hints *hints = 0;
struct sockaddr_storage ss;
unsigned i;
@@ -5895,9 +6014,12 @@
if (!(hints = dns_hints_open(resconf, &error))) goto error;
- for (i = 0; i < lengthof(root_hints); i++) {
+ for (i = 0; i < nroot_hints; i++) {
af = root_hints[i].af;
if ((error = dns_pton(af, root_hints[i].addr, dns_sa_addr(af, &ss, NULL)))) goto error;
+ if (getenv("BELLE_SIP_LOG_ROOT_HINTS")) {
+ fprintf(stderr, "src/dns/dns.c:dns_hints_root():addr=%s, af=%d\n",root_hints[i].addr,af);
+ }
*dns_sa_port(af, &ss) = htons(53);
ss.ss_family = af;
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