From 8e7ea6742a94ea62b421d7184e9eab17fb5da934 Mon Sep 17 00:00:00 2001
From: Joel Grunbaum <joelgrun@gmail.com>
Date: Wed, 21 Oct 2020 12:29:13 +0000
Subject: [PATCH] Added threading, progress and some comments, nearly done
---
slist.c | 2
Makefile | 2
main.c | 103 ++++++++++++++++++++++++++-------
dns.c | 8 ++
include/servers.h | 8 ++
5 files changed, 98 insertions(+), 25 deletions(-)
diff --git a/Makefile b/Makefile
index c67c988..cdddcb0 100644
--- a/Makefile
+++ b/Makefile
@@ -2,7 +2,7 @@
_OBJ=main.o dns.o slist.o
_DEPS=dns.h servers.h slist.h
IDIR=include
-CFLAGS=-I$(IDIR) -Wall -g
+CFLAGS=-I$(IDIR) -Wall -g -lpthread
ODIR=obj
SRCDIR=src
diff --git a/dns.c b/dns.c
index 3784d2f..ad58873 100644
--- a/dns.c
+++ b/dns.c
@@ -69,6 +69,8 @@
char* rdata;
};
+// Test server dns_ip as IPv4 string for hostname
+// Writes received packet to buf, which is supplied and returns time for request
struct timespec resolve(unsigned char* buf, char* hostname, char* dns_ip, int query_type)
{
int s, i;
@@ -120,6 +122,7 @@
i = recvfrom(s, (char*)buf, 65536, 0, (struct sockaddr*)&dest, (socklen_t*)&i);
clock_gettime(CLOCK_MONOTONIC, &end);
+ // Make sure packet was returned
if (i == -1)
total.tv_nsec = -1;
else
@@ -132,6 +135,7 @@
return total;
}
+// Print dns packet content, not terribly reliable but works for testing resolve with A requests
void print_packet(unsigned char* buf)
{
struct RES_RECORD answers[20], auth[20], addit[20];
@@ -242,7 +246,8 @@
}
}
-
+// convert from dot format to dns format
+// eg google.com to 6google3com
void change_to_DNS_name_format(unsigned char* dns, unsigned char* host)
{
int lock = 0;
@@ -262,6 +267,7 @@
*dns++ = '\0';
}
+// Convert from dns to dot format
char* read_name(unsigned char* reader, unsigned char* buffer, int* count)
{
char* name;
diff --git a/include/servers.h b/include/servers.h
index f1da678..64b8d40 100644
--- a/include/servers.h
+++ b/include/servers.h
@@ -1,3 +1,11 @@
+/**
+ * Unfortunately, wanting to make cross platform required static lists of hosts and dns servers
+ * At least until I think of a good way to do it
+ * Hosts came from alexa top 50 one day and dns are from quick searching for common servers
+ * DNS only takes IPv4 server addresses
+ * The definitions must be the same as the size of the arrays, as they are required later on to be read properly
+ **/
+
#define NUM_HOSTNAMES 50
#define NUM_DNS 20
diff --git a/main.c b/main.c
index 3db7eee..2f86224 100644
--- a/main.c
+++ b/main.c
@@ -1,29 +1,56 @@
+/**
+ * A basic dns benchmark testing program
+ * Tests servers in parallel so reasonably fast
+ * Tried to only use POSIX functions to ensure cross platform compatibility
+ **/
+
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <time.h>
+#include <pthread.h>
#include "dns.h"
#include "servers.h"
#include "slist.h"
#define NUM_TESTS 10
-int test_dns(struct dns_list *dnss, struct hosts_list *hosts, int num_hosts, int num_tests);
-struct timespec test_server(struct dns_list *dns, struct hosts_list *hosts, int num_hosts, int num_tests);
+/* struct test_server_input { */
+/* int dns; */
+/* //struct hosts_list *hosts; */
+/* int num_hosts; */
+/* int num_tests; */
+/* }; */
+
+/* struct progress_input { */
+/* int num_hosts; */
+/* int num_tests; */
+/* int num_servers; */
+/* }; */
+
+int test_dns(void);
+void *test_server(void *in);
+void *print_progress(void *in);
+
+// All global variables as passing to threads in structs caused corruption
+// 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;
+struct hosts_list *hosts = NULL;
+struct dns_list *servers = NULL;
int main(int argc, char** argv)
{
- int option, num_hosts = 0, added_hosts = 0, num_tests = NUM_TESTS;
- struct hosts_list *servers_hosts = NULL;
- struct dns_list *servers_dns = NULL;
+ int option, added_hosts = 0;
while((option = getopt(argc, argv, "s:h:t:n:")) != -1) {
switch (option) {
case 's': //server to use
- add_dns_server(&servers_dns, optarg);
+ add_dns_server(&servers, optarg);
+ num_servers++;
break;
case 'h': //hostname to search
- add_hosts_server(&servers_hosts, optarg);
+ add_hosts_server(&hosts, optarg);
added_hosts++;
break;
case 't': //set number of hosts to test
@@ -35,8 +62,8 @@
case '?':
default:
printf("Error: invalid option -%c\n", optopt);
- free_dns_list(&servers_dns);
- free_hosts_list(&servers_hosts);
+ free_dns_list(&servers);
+ free_hosts_list(&hosts);
exit(1);
}
}
@@ -44,32 +71,47 @@
num_hosts = NUM_HOSTNAMES + added_hosts;
}
for (int i = added_hosts; i < num_hosts; i++) {
- add_hosts_server(&servers_hosts, HOSTNAMES[i-added_hosts]);
+ add_hosts_server(&hosts, HOSTNAMES[i-added_hosts]);
}
for (int i = 0; i < NUM_DNS; i++) {
- add_dns_server(&servers_dns, DNS_SERVERS[i]);
+ add_dns_server(&servers, DNS_SERVERS[i]);
}
- test_dns(servers_dns, servers_hosts, num_hosts, num_tests);
- sort_servers(&servers_dns);
- print_servers(servers_dns);
- free_dns_list(&servers_dns);
- free_hosts_list(&servers_hosts);
+ test_dns();
+ sort_servers(&servers);
+ print_servers(servers);
+ free_dns_list(&servers);
+ free_hosts_list(&hosts);
return 0;
}
-int test_dns(struct dns_list *dnss, struct hosts_list *hosts, int num_hosts, int num_tests)
+// Test each dns server individually
+// Each test runs in its own thread and results are written to the respective dns_list
+int test_dns(void)
{
- struct dns_list *curr = dnss;
+ struct dns_list *curr = servers;
+ int i = 0;
+ pthread_t *threads = malloc(num_servers*sizeof(pthread_t));
+ pthread_t progress;
+ pthread_create(&progress, NULL, print_progress, NULL);
while (curr) {
- test_server(curr, hosts, num_hosts, num_tests);
+ pthread_create(&threads[i], NULL, test_server, (void*)curr);
curr = curr->next;
+ i++;
}
+ for (int i = 0; i < num_servers; i++) {
+ pthread_join(threads[i], NULL);
+ }
+ pthread_cancel(progress);
+ printf("\r100.00%% done\n");
+ free(threads);
return 0;
}
-struct timespec test_server(struct dns_list *dns, struct hosts_list *hosts, int num_hosts, int num_tests)
+// Tests an individual dns server with all the hostnames configured
+void *test_server(void *in)
{
unsigned long long avg_nsec = 0;
+ struct dns_list *dns = (struct dns_list *)in;
dns->time.tv_sec = 0; dns->time.tv_nsec = 0;
for (int i = 0; i < num_tests; i++) {
struct hosts_list *curr = hosts;
@@ -77,19 +119,34 @@
struct timespec run;
unsigned char buf[65536];
run = resolve(buf, curr->server, dns->server, T_A);
- if (run.tv_sec == -1)
+ if (run.tv_sec == -1) //currently ignore failed tests, need to figure out what to do with them
continue;
dns->time.tv_sec += run.tv_sec;
dns->time.tv_nsec += run.tv_nsec;
- if (dns->time.tv_nsec >= 1000000000) {
+ if (dns->time.tv_nsec >= 1000000000) { //nanoseconds have overflowed into seconds
dns->time.tv_sec += 1;
dns->time.tv_nsec -= 1000000000;
}
+ tests_done++;
curr = curr->next;
}
}
avg_nsec = 1000000000*(dns->time.tv_sec%(num_hosts*num_tests))+dns->time.tv_nsec;
dns->time.tv_sec = dns->time.tv_sec/(num_hosts*num_tests);
dns->time.tv_nsec = avg_nsec/(num_hosts*num_tests);
- return dns->time;
+ return NULL;
+}
+
+// Prints the progress every 0.1s for an indication of speed
+// tests_done is being written to in parallel, so may be overwritten but serves as a decent estimate of the progress
+void *print_progress(void *in)
+{
+ struct timespec s;
+ s.tv_sec = 0; s.tv_nsec = 100000000;
+ while (1) {
+ printf("\r%.2f%% done", ((float)tests_done)/(num_servers*num_hosts*num_tests) * 100);
+ fflush(stdout);
+ nanosleep(&s, NULL);
+ }
+ return NULL;
}
diff --git a/slist.c b/slist.c
index 7aa0413..45bb3e6 100644
--- a/slist.c
+++ b/slist.c
@@ -65,6 +65,8 @@
return 0;
}
+// Sort with merge sort as works well for linked lists
+// Copied from https://www.geeksforgeeks.org/merge-sort-for-linked-list/
int sort_servers(struct dns_list **headRef)
{
struct dns_list *head = *headRef;
--
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