Allow setting of more DNS options via API; from Nick Mathewson!!!

svn:r318

diff --git a/evdns.c b/evdns.c
index f70aa0a37579014560421967dd1a9c324badfec6..8679f0450b26b969728a27165577ca44897b07a9 100644 (file)
--- a/evdns.c
+++ b/evdns.c
@@ -1898,6 +1898,64 @@ strtoint(const char *const str) {
        return r;
 }
 
+// helper version of atoi that returns -1 on error and clips to bounds.
+static int
+strtoint_clipped(const char *const str, int min, int max)
+{
+       int r = strtoint(str);
+       if (r == -1)
+               return r;
+       else if (r<min)
+               return min;
+       else if (r>max)
+               return max;
+       else
+               return r;
+}
+
+// exported function
+int
+evdns_set_option(const char *option, const char *val, int flags)
+{
+       if (!strncmp(option, "ndots:", 6)) {
+               const int ndots = strtoint(val);
+               if (ndots == -1) return -1;
+               if (!(flags & DNS_OPTION_SEARCH)) return 0;
+               log(EVDNS_LOG_DEBUG, "Setting ndots to %d", ndots);
+               if (!global_search_state) global_search_state = search_state_new();
+               if (!global_search_state) return -1;
+               global_search_state->ndots = ndots;
+       } else if (!strncmp(option, "timeout:", 8)) {
+               const int timeout = strtoint(val);
+               if (timeout == -1) return -1;
+               if (!(flags & DNS_OPTION_MISC)) return 0;
+               log(EVDNS_LOG_DEBUG, "Setting timeout to %d", timeout);
+               global_timeout.tv_sec = timeout;
+       } else if (!strncmp(option, "max-timeouts:", 12)) {
+               const int maxtimeout = strtoint_clipped(val, 1, 255);
+               if (maxtimeout == -1) return -1;
+               if (!(flags & DNS_OPTION_MISC)) return 0;
+               log(EVDNS_LOG_DEBUG, "Setting maximum allowed timeouts to %d",
+                       maxtimeout);
+               global_max_nameserver_timeout = maxtimeout;
+       } else if (!strncmp(option, "max-inflight:", 13)) {
+               const int maxinflight = strtoint_clipped(val, 1, 65000);
+               if (maxinflight == -1) return -1;
+               if (!(flags & DNS_OPTION_MISC)) return 0;
+               log(EVDNS_LOG_DEBUG, "Setting maximum inflight requests to %d",
+                       maxinflight);
+               global_max_requests_inflight = maxinflight;
+       } else if (!strncmp(option, "attempts:", 9)) {
+               int retries = strtoint(val);
+               if (retries == -1) return -1;
+               if (retries > 255) retries = 255;
+               if (!(flags & DNS_OPTION_MISC)) return 0;
+               log(EVDNS_LOG_DEBUG, "Setting retries to %d", retries);
+               global_max_retransmits = retries;
+       }
+       return 0;
+}
+
 static void
 resolv_conf_parse_line(char *const start, int flags) {
        char *strtok_state;
@@ -1907,7 +1965,7 @@ resolv_conf_parse_line(char *const start, int flags) {
        char *const first_token = strtok_r(start, delims, &strtok_state);
        if (!first_token) return;
 
-       if (!strcmp(first_token, "nameserver")) {
+       if (!strcmp(first_token, "nameserver") && (flags & DNS_OPTION_NAMESERVERS)) {
                const char *const nameserver = NEXT_TOKEN;
                struct in_addr ina;
 
@@ -1931,30 +1989,9 @@ resolv_conf_parse_line(char *const start, int flags) {
                search_reverse();
        } else if (!strcmp(first_token, "options")) {
                const char *option;
-
                while ((option = NEXT_TOKEN)) {
-                       if (!strncmp(option, "ndots:", 6)) {
-                               const int ndots = strtoint(&option[6]);
-                               if (ndots == -1) continue;
-                               if (!(flags & DNS_OPTION_SEARCH)) continue;
-                               log(EVDNS_LOG_DEBUG, "Setting ndots to %d", ndots);
-                               if (!global_search_state) global_search_state = search_state_new();
-                                if (!global_search_state) return;
-                               global_search_state->ndots = ndots;
-                       } else if (!strncmp(option, "timeout:", 8)) {
-                               const int timeout = strtoint(&option[8]);
-                               if (timeout == -1) continue;
-                               if (!(flags & DNS_OPTION_MISC)) continue;
-                               log(EVDNS_LOG_DEBUG, "Setting timeout to %d", timeout);
-                               global_timeout.tv_sec = timeout;
-                       } else if (!strncmp(option, "attempts:", 9)) {
-                               int retries = strtoint(&option[9]);
-                               if (retries == -1) continue;
-                               if (retries > 255) retries = 255;
-                               if (!(flags & DNS_OPTION_MISC)) continue;
-                               log(EVDNS_LOG_DEBUG, "Setting retries to %d", retries);
-                               global_max_retransmits = retries;
-                       }
+                       const char *val = strchr(option, ':');
+                       evdns_set_option(option, val ? val+1 : "", flags);
                }
        }
 #undef NEXT_TOKEN
@@ -1987,7 +2024,7 @@ evdns_resolv_conf_parse(int flags, const char *const filename) {
        if (fstat(fd, &st)) { err = 2; goto out1; }
        if (!st.st_size) {
                evdns_resolv_set_defaults(flags);
-               err = 0;
+               err = (flags & DNS_OPTION_NAMESERVERS) ? 6 : 0;
                goto out1;
        }
        if (st.st_size > 65535) { err = 3; goto out1; }  // no resolv.conf should be any bigger
@@ -2016,6 +2053,7 @@ evdns_resolv_conf_parse(int flags, const char *const filename) {
        if (!server_head && (flags & DNS_OPTION_NAMESERVERS)) {
                // no nameservers were configured.
                evdns_nameserver_ip_add("127.0.0.1");
+               err = 6;
        }
        if (flags & DNS_OPTION_SEARCH && (!global_search_state || global_search_state->num_domains == 0)) {
                search_set_from_hostname();

diff --git a/evdns.h b/evdns.h
index 4b4f5a931662662b3932caf3b005637d0613f8aa..36c0d13eabd387d534e3920411a4634604d1be7f 100644 (file)
--- a/evdns.h
+++ b/evdns.h
@@ -213,6 +213,7 @@
  *    3 file too large
  *    4 out of memory
  *    5 short read from file
+ *    6 no nameservers in file
  *
  * Internals:
  *
@@ -298,6 +299,7 @@ struct in_addr;
 struct in6_addr;
 int evdns_resolve_reverse(struct in_addr *in, int flags, evdns_callback_type callback, void *ptr);
 int evdns_resolve_reverse_ipv6(struct in6_addr *in, int flags, evdns_callback_type callback, void *ptr);
+int evdns_set_option(const char *option, const char *val, int flags);
 int evdns_resolv_conf_parse(int flags, const char *);
 #ifdef MS_WINDOWS
 int evdns_config_windows_nameservers(void);