Scan for DHCP and RA in parallel at the same time to shorten the over…

…all runtime of the dhcp-discover tool

Signed-off-by: DL6ER <[email protected]>

src/tools/dhcp-discover.c

@@ -49,8 +49,7 @@
 
 // Maximum time we wait for incoming DHCPOFFERs
 // (seconds)
-#define DHCPOFFER_TIMEOUT 6
-#define DHCPV6_TIMEOUT 4
+#define SCAN_TIMEOUT 6
 
 // How many threads do we spawn at maximum?
 // This is also the limit for interfaces
@@ -571,7 +570,7 @@ static void get_dhcp_offer(const int sock, const uint32_t xid, const char *iface
 	time(&start_time);
 
 	// receive as many responses as we can
-	while(time(&current_time) && (current_time-start_time) < DHCPOFFER_TIMEOUT)
+	while(time(&current_time) && (current_time-start_time) < SCAN_TIMEOUT)
 	{
 		memset(&source, 0, sizeof(source));
 		memset(&offer_packet, 0, sizeof(offer_packet));
@@ -675,10 +674,16 @@ static void get_dhcp_offer(const int sock, const uint32_t xid, const char *iface
 #endif
 }
 
-static void *dhcp_discover_iface(void *args)
+static void *dhcp_discover_iface_v4(void *args)
 {
 	// Get interface details
 	const char *iface = ((struct ifaddrs*)args)->ifa_name;
+	char *thread_name = malloc(strlen(iface) + 4);
+	sprintf(thread_name, "%s-v4", iface);
+
+	// Set interface name as thread name
+	prctl(PR_SET_NAME, thread_name, 0, 0, 0);
+	free(thread_name);
 
 	// Set interface name as thread name
 	prctl(PR_SET_NAME, iface, 0, 0, 0);
@@ -710,11 +715,24 @@ static void *dhcp_discover_iface(void *args)
 	if(dhcp_socket > 0)
 		close(dhcp_socket);
 
+	pthread_exit(NULL);
+}
+
+static void *dhcp_discover_iface_v6(void *args)
+{
+	// Get interface details
+	const char *iface = ((struct ifaddrs*)args)->ifa_name;
+	char *thread_name = malloc(strlen(iface) + 4);
+	sprintf(thread_name, "%s-v6", iface);
+
+	// Set interface name as thread name
+	prctl(PR_SET_NAME, thread_name, 0, 0, 0);
+	free(thread_name);
+
 	// Perform the same scan for DHCPv6
-	const int responses = dhcpv6_discover_iface(iface, DHCPV6_TIMEOUT);
-	if(responses > -1)
-		printf("DHCPv6 packets received on %s%s%s: %i\n",
-		       cli_bold(), iface, cli_normal(), responses);
+	const int responses = dhcpv6_discover_iface(iface, SCAN_TIMEOUT);
+	printf("RAs received on %s%s%s: %i\n",
+	       cli_bold(), iface, cli_normal(), responses);
 
 	pthread_exit(NULL);
 }
@@ -741,12 +759,12 @@ int run_dhcp_discover(void)
 	// Only print to terminal, disable log file
 	log_ctrl(false, true);
 
-	printf("Scanning all your interfaces for DHCPv4 and DHCPv6 servers\n");
-	printf("Timeout: %d + %d seconds\n", DHCPOFFER_TIMEOUT, DHCPV6_TIMEOUT);
+	printf("Scanning all your interfaces for DHCP servers and IPv6 routers\n");
+	printf("Timeout: %d seconds\n", SCAN_TIMEOUT);
 
 	// Get interface names for available interfaces on this machine
 	// and launch a thread for each one
-	pthread_t scanthread[MAXTHREADS];
+	pthread_t scanthread[2*MAXTHREADS];
 	pthread_attr_t attr;
 	// Initialize thread attributes object with default attribute values
 	pthread_attr_init(&attr);
@@ -784,10 +802,19 @@ int run_dhcp_discover(void)
 				continue;
 			}
 
-			// Create a probing thread for this interface
-			if(pthread_create(&scanthread[tid], &attr, dhcp_discover_iface, tmp ) != 0)
+			// Create a DHCP probing thread for this interface
+			if(pthread_create(&scanthread[tid], &attr, dhcp_discover_iface_v4, tmp ) != 0)
 			{
-				printf_locked("Unable to launch thread for interface %s, skipping...",
+				printf_locked("Unable to launch DHCP thread for interface %s, skipping...",
+				              tmp->ifa_name);
+				tmp = tmp->ifa_next;
+				continue;
+			}
+
+			// Create a RA probing thread for this interface
+			if(pthread_create(&scanthread[2*tid], &attr, dhcp_discover_iface_v6, tmp ) != 0)
+			{
+				printf_locked("Unable to launch RA thread for interface %s, skipping...",
 				              tmp->ifa_name);
 				tmp = tmp->ifa_next;
 				continue;
@@ -803,7 +830,10 @@ int run_dhcp_discover(void)
 
 	// Wait for all threads to join back with us
 	for(tid--; tid > -1; tid--)
+	{
 		pthread_join(scanthread[tid], NULL);
+		pthread_join(scanthread[2*tid], NULL);
+	}
 
 	// Free linked-list of interfaces on this client
 	freeifaddrs(addrs);

src/tools/dhcpv6-discover.c

@@ -647,7 +647,7 @@ static ssize_t recv_adv(int fd, const struct sockaddr_in6 *tgt, const char *ifna
 	unsigned responses = 0;
 
 	// Get the current time and add the timeout
-	clock_gettime (CLOCK_MONOTONIC, &end);
+	clock_gettime(CLOCK_MONOTONIC, &end);
 	end.tv_sec += timeout;
 
 	// Receiving packets until timeout
@@ -665,16 +665,21 @@ static ssize_t recv_adv(int fd, const struct sockaddr_in6 *tgt, const char *ifna
 			if (val < 0) val = 0;
 		}
 
-		// Wait for reply
+		// Wait for reply (retries on EINTR)
 		struct pollfd pollfd = { .fd = fd, .events = POLLIN, .revents = 0 };
-		val = poll(&pollfd, 1, val);
+		do {
+			val = poll(&pollfd, 1, val);
+		} while (val == -1 && errno == EINTR);
 
 		// Check for errors
-		if (val < 0)
+		if(val < 0)
+		{
+			perror("Polling for ICMPv6 packet");
 			break;
+		}
 
 		// Check for timeout
-		if (val == 0)
+		if(val == 0)
 			return responses;
 
 		// Received a packet
@@ -721,7 +726,6 @@ static ssize_t recv_adv(int fd, const struct sockaddr_in6 *tgt, const char *ifna
  */
 static int do_discoverv6(const int fd, const char *ifname, const unsigned int timeout)
 {
-	unsigned int retry = 3;
 	struct sockaddr_in6 tgt = { 0 };
 
 	// Automatically close the socket on exec
@@ -749,7 +753,10 @@ static int do_discoverv6(const int fd, const char *ifname, const unsigned int ti
 	// Resolves target's IPv6 address
 	const char *hostname = "ff02::2"; // All routers multicast address
 	if(get_ipv6_by_name(hostname, ifname, &tgt) != 0)
-		goto error;
+	{
+		close(fd);
+		return -1;
+	}
 
 	char s[INET6_ADDRSTRLEN] = { 0 };
 	inet_ntop (AF_INET6, &tgt.sin6_addr, s, sizeof (s));
@@ -762,39 +769,40 @@ static int do_discoverv6(const int fd, const char *ifname, const unsigned int ti
 	// Build a Router Solicitation message
 	const ssize_t plen = build_solicit(&packet);
 	if(plen == -1)
-		goto error;
+	{
+		close(fd);
+		return -1;
+	}
 
-	while(retry > 0)
+	/* sends a Solitication */
+	if(sendto(fd, &packet, plen, 0,
+	   (const struct sockaddr *)&dst,
+	   sizeof(dst)) != plen)
 	{
-		/* sends a Solitication */
-		if(sendto(fd, &packet, plen, 0,
-				(const struct sockaddr *)&dst,
-				sizeof(dst)) != plen)
-		{
-			perror("Sending ICMPv6 packet");
-			goto error;
-		}
-		retry--;
+		perror("Sending ICMPv6 packet");
+		close(fd);
+		return -1;
+	}
 
-		/* receives an Advertisement */
-		const ssize_t val = recv_adv(fd, &tgt, ifname, timeout);
-		if(val > 0)
-		{
-			close(fd);
-			return val;
-		}
-//		else if(val == 0) // Timed out
-		if(val < 0)
-			goto error;
+	/* receives an Advertisement */
+	const ssize_t val = recv_adv(fd, &tgt, ifname, timeout);
+	if(val > 0)
+	{
+		close(fd);
+		return val;
+	}
+//	else if(val == 0) // Timed out
+	if(val < 0)
+	{
+		// Error
+		perror("Receiving ICMPv6 packet");
+		close(fd);
+		return -1;
 	}
 
-	close(fd);
 	// No DHCPv6 responses received
-	return 0;
-
-error:
 	close(fd);
-	return -1;
+	return 0;
 }
 
 int dhcpv6_discover_iface(const char *ifname, const unsigned int timeout)