now sends ICMP_ECHO_REQUEST and recvs ICMP_ECHO_RESPONSE

.vscode/settings.json

@@ -0,0 +1,3 @@
+{
+    "C_Cpp.errorSquiggles": "disabled"
+}

includes/main.h

@@ -13,6 +13,9 @@
 #include <errno.h>
 #include <string.h>
 #include <netinet/ip_icmp.h>
+#include <poll.h>
+#include <time.h>
+#include <sys/time.h>
 
 struct arguments {
     char* args[1];

srcs/main.c

@@ -25,7 +25,7 @@ static error_t parse_opt(int key, char* arg, struct argp_state* state) {
             break;
         case ARG_TTL:
             arguments->ttl = strtoul(arg, NULL, 10);
-            __attribute__ ((fallthrough));
+            __attribute__((fallthrough));
         case ARGP_KEY_ARG:
             if (state->arg_num >= 2)
                 argp_usage(state);
@@ -49,6 +49,8 @@ int sock = 0;
 
 static struct sockaddr_in destination;
 
+struct timespec sendt;
+
 unsigned long xmit = 0;
 unsigned long recvd = 0;
 
@@ -56,31 +58,45 @@ double min = 0;
 double max = 0;
 double avg = 0;
 
-uint16_t calc_checksum(void * b, const size_t l) {
-    uint16_t sum = 0;
+uint16_t calc_checksum(void* b, size_t len) {
+    unsigned short* buf = b;
+    unsigned int sum = 0;
+    unsigned short result;
 
-    for (size_t i = 0; i < l; i++) {
-        sum += *((uint16_t*)b + i);
+    for (sum = 0; len > 1; len -= 2) {
+        sum += *buf++;
     }
 
-    return ~sum;
+    if (len == 1) {
+        sum += *(unsigned char*)buf;
+    }
+
+    sum = (sum >> 16) + (sum & 0xFFFF);
+    sum += (sum >> 16);
+    result = ~sum;
+    return result;
 }
 
 void send_ping() {
     struct ping_pkt packet = {0};
 
     packet.hdr.type = ICMP_ECHO;
+    packet.hdr.code = 0;
     packet.hdr.un.echo.id = getpid();
     packet.hdr.un.echo.sequence = xmit++;
 
-    for (long unsigned i = 0; i < sizeof(packet.msg) - 1; ++i) {
-        packet.msg[i] = (char)i;
+    struct timeval tmp_tv;
+    gettimeofday(&tmp_tv, NULL);
+
+    memcpy(packet.msg, &tmp_tv, sizeof(tmp_tv));
+    for (long unsigned i = 0; i < sizeof(packet.msg) - sizeof(tmp_tv); ++i) {
+        packet.msg[sizeof(tmp_tv) + i] = (char)i;
     }
-    packet.msg[sizeof(packet.msg) - 1] = '\0';
 
     packet.hdr.checksum = calc_checksum(&packet, sizeof(packet));
 
     sendto(sock, &packet, sizeof(packet), 0, (struct sockaddr*)&destination, sizeof(destination));
+    clock_gettime(CLOCK_MONOTONIC, &sendt);
     alarm(1);
 }
 
@@ -94,6 +110,10 @@ void sig_handler(int sig) {
 
 int main(int argc, char** argv) {
     struct arguments arguments;
+    int timeout = 3000;
+    struct timespec recvt;
+    struct pollfd fds[1];
+
     arguments.verbose = 0;
     arguments.ttl = 64;
     argp_parse(&argp, argc, argv, 0, 0, &arguments);
@@ -121,6 +141,9 @@ int main(int argc, char** argv) {
         exit(1);
     }
 
+    fds[0].fd = sock;
+    fds[0].events = POLLIN;
+
     struct sigaction sig_handle;
 
     sig_handle.sa_handler = sig_handler;
@@ -128,17 +151,49 @@ int main(int argc, char** argv) {
     sigaction(SIGINT, &sig_handle, 0);
     sigaction(SIGALRM, &sig_handle, 0);
 
-    alarm(1);
+    send_ping();
 
     while (true) {
+        int ret = poll(fds, 1, timeout);
+        if (ret > 0) {
+            if (fds[0].revents & POLLIN) {
+                char buf[100];
+
+                long int bytes_received = recvfrom(sock, buf, 100, 0, NULL, NULL);
+
+                if (bytes_received < 0) {
+                    perror("recvfrom failed");
+                    return 1;
+                }
+
+                clock_gettime(CLOCK_MONOTONIC, &recvt);
+
+                struct ip* ip_header = (struct ip*)buf;
+                struct icmphdr* icmp_reply = (struct icmphdr*)(buf + (ip_header->ip_hl << 2));
+
+                int rtt_n =
+                    ((recvt.tv_sec * 1000 + recvt.tv_nsec / 1000000) - (sendt.tv_sec * 1000 + sendt.tv_nsec / 1000000));
+                int rtt_r = ((recvt.tv_nsec - sendt.tv_nsec) % 1000000 / 1000);
+
+                printf("%zd bytes from %s: icmp_seq=%d ttl=%d time=%d.%d ms \n", bytes_received, arguments.args[0],
+                       icmp_reply->un.echo.sequence, ip_header->ip_ttl, rtt_n, rtt_r);
+                recvd++;
+            }
+        } else if (ret == 0) {
+            printf("No reply received within the timeout period\n");
+        } else {
+            perror("Poll failed");
+        }
+
+        pause();
 
         if (stop) {
             break;
         }
     }
     printf("---- %s ping statistics ----\n", arguments.args[0]);
-    printf("%zu packets transmitted, %zu packets received, %%zu%% packet loss\n", xmit,
-           recvd /*, (xmit - recv) / xmit * 100*/);
+    printf("%zu packets transmitted, %zu packets received, %zu%% packet loss\n", xmit, recvd,
+           (xmit - recvd) / xmit * 100);
     // printf("round-trip min/avg/max/stddev = %f/%f/%f/%f ms\n");
     close(sock);
 }