From 7bd5eb7a1f260d504b8235968dc793abb6b023eb Mon Sep 17 00:00:00 2001
From: Nate Straz <nstraz@redhat.com>
Date: Thu, 3 Jan 2008 14:35:45 +0000
Subject: Switch to using a select with a timeout instead of a loop of
 recvfroms and sleeps in btime().  This makes it easier to tune how long to
 wait for a heartbeat.  Now I can get heartbeats over my vpn connection.

---
 btime.c     | 36 +++++++++++++++++++++---------------
 btime_int.h |  1 -
 2 files changed, 21 insertions(+), 16 deletions(-)

diff --git a/btime.c b/btime.c
index 4b4c474..6bd36c0 100644
--- a/btime.c
+++ b/btime.c
@@ -59,6 +59,8 @@ btime(const char *host)
 	unsigned int btime = 0;
 	ssize_t nbytes;	
 	int retry;
+	fd_set sdset;
+	struct timeval timeout;
 
 	if ((sd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
 		fprintf(stderr, "Could not create socket: %s\n", 
@@ -107,24 +109,26 @@ btime(const char *host)
 		}
 	}
 	
+	FD_ZERO(&sdset);
+	FD_SET(sd, &sdset);
+	do {
+		retry = 0;
 
-	memset(&resp_addr, 0, sizeof resp_addr);
-	memset(response, 0, BTIME_MSGLEN);
-	for (retry = 0; retry < MAX_RETRY; retry++) {
-		resp_addr_len = sizeof resp_addr;
-		if ((nbytes = recvfrom(sd, &response, BTIME_MSGLEN, MSG_DONTWAIT, 
-	         (struct sockaddr *)&resp_addr, &resp_addr_len)) < 0) {
-			if (errno == EAGAIN) {
-				usleep(RETRY_SLEEP);
-				continue;
-			} else {
-				/* Non EAGAIN error... */
-				break;
-			}
+		timeout.tv_sec = 0;
+		timeout.tv_usec = 250000;
+
+		if (select(sd + 1, &sdset, NULL, NULL, &timeout) != 1) {
+			/* Either an error or a timeout, we don't need to retry */
+			break;
 		}
 
+		memset(&resp_addr, 0, sizeof resp_addr);
+		memset(response, 0, BTIME_MSGLEN);
+		resp_addr_len = sizeof resp_addr;
+		nbytes = recvfrom(sd, &response, BTIME_MSGLEN, MSG_DONTWAIT, 
+				(struct sockaddr *)&resp_addr, &resp_addr_len);
 		if (nbytes == 0) {
-			/* Nothing received, try again */
+			/* Nothing received */
 			continue;
 		} else if (response[0] == 'B' && response[1] == 'T') {
 			/* Check for new style cookie */
@@ -133,6 +137,7 @@ btime(const char *host)
 				break;
 			} else {
 				/* ignore the invalid btime cookie */
+				retry = 1;
 				continue;
 			}
 		} else if (!same_addr(&serv_addr, &resp_addr)) {
@@ -143,13 +148,14 @@ btime(const char *host)
 					rstr, sstr);
 			free(rstr);
 			free(sstr);
+			retry = 1;
 			continue;
 		} else {
 			/* If peer matches, accept the bare btime */
 			btime = strtoul(response, (char **)NULL, 10);
 			break;
 		}
-	}
+	} while (retry);
 
 	close(sd);
 
diff --git a/btime_int.h b/btime_int.h
index b4d34ba..6872fce 100644
--- a/btime_int.h
+++ b/btime_int.h
@@ -26,7 +26,6 @@
 #define BTIME_PORT   23456
 #define BTIME_MSGLEN 128
 #define MAX_RETRY    40
-#define RETRY_SLEEP  1000
 
 #define COOKIE_RANDOM_PARTS 4
 #define COOKIE_LEN (3 + (COOKIE_RANDOM_PARTS * sizeof(int32_t)))
-- 
cgit