From 95dada12eb1c7c6d52a52b89e4bf1a56b95d692a Mon Sep 17 00:00:00 2001
From: Joel Grunbaum <joelgrun@gmail.com>
Date: Wed, 01 Jun 2022 04:52:13 +0000
Subject: [PATCH] checks for server conductibility if user is root
---
main.c | 40 +++++++++++++++++++++++++++++++++++-----
1 files changed, 35 insertions(+), 5 deletions(-)
diff --git a/main.c b/main.c
index 780bb36..9787a55 100644
--- a/main.c
+++ b/main.c
@@ -24,7 +24,7 @@
// Variables are only modified before threads are created and as such are
// thread-safe tests_done is modified to provide a rough count of number of
// tests being completed for progress measurement
-int tests_done = 0, num_tests = NUM_TESTS, num_servers = NUM_DNS, num_hosts = 0;
+int tests_done = 0, num_tests = NUM_TESTS, num_servers = 0, num_hosts = 0;
struct hosts_list* hosts = NULL;
struct dns_list* servers = NULL;
@@ -76,6 +76,7 @@
}
for (int i = 0; i < NUM_DNS; i++) {
add_dns_server(&servers, (char*)DNS_SERVERS[i]);
+ num_servers++;
}
test_dns();
sort_servers(&servers);
@@ -92,13 +93,43 @@
{
struct dns_list* curr = servers;
int i = 0;
- pthread_t* threads = malloc(num_servers * sizeof(pthread_t));
+ int init_num_servers = num_servers;
+ pthread_t* threads;
pthread_t progress;
+ // Check each server for reachability, can't be done in parallel as incorrect packets are received
+ // reachable() requires raw packets, which needs root
+ if (getuid() == 0) {
+ while (curr) {
+ printf("\rTesting reachability: %d/%d", i, init_num_servers); fflush(stdout);
+ unsigned char* buf[65535];
+ int error_count = 0;
+ curr->errors = 0;
+ // retry 10 times for UDP unreliability
+ for (int i = 0; i < 10; i++) {
+ error_count += (reachable((unsigned char*)buf, curr->server) != 0);
+ }
+ /* fprintf(stderr, "ip: %s, ec: %d\n", curr->server, error_count); */
+ // 30% error rate means unreachable
+ if (error_count >= 3) {
+ curr->errors = -1;
+ num_servers--;
+ }
+ curr = curr->next;
+ i++;
+ }
+ printf("\rTesting reachability: %d/%d\n", i, init_num_servers);
+ }
+
+ threads = malloc(num_servers * sizeof(pthread_t));
+ curr = servers;
+ i = 0;
pthread_create(&progress, NULL, print_progress, NULL);
while (curr) {
- pthread_create(&threads[i], NULL, test_server, (void*)curr);
+ if (curr->errors == 0) {
+ pthread_create(&threads[i], NULL, test_server, (void*)curr);
+ i++;
+ }
curr = curr->next;
- i++;
}
for (int i = 0; i < num_servers; i++) {
pthread_join(threads[i], NULL);
@@ -116,7 +147,6 @@
struct dns_list* dns = (struct dns_list*)in;
dns->time.tv_sec = 0;
dns->time.tv_nsec = 0;
- dns->errors = 0;
for (int i = 0; i < num_tests; i++) {
struct hosts_list* curr = hosts;
while (curr) {
--
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