Copy data from ip-file to name-file

Also remove the "optimization" strcmp, as it was buggy.

Signed-off-by: Joern Engel <joern@logfs.org>

1 files changed, 49 insertions, 4 deletions

diff --git a/cancd.c b/cancd.c
index 467ecab..15fff83 100644
--- a/cancd.c
+++ b/cancd.c
@@ -364,7 +364,7 @@ static struct source_ip *get_source_ip(struct sockaddr_in *addr)
 	if (!sip) {
 		sip = calloc(1, sizeof(*sip));
 		sip->had_newline = 1;
-		sip->filename = get_path(&addr->sin_addr);
+		sip->tmpfilename = get_path(&addr->sin_addr);
 		err = btree_insert32(&btree, key, sip);
 		assert(!err);
 		sem_post(&dns_sem);
@@ -372,13 +372,60 @@ static struct source_ip *get_source_ip(struct sockaddr_in *addr)
 	return sip;
 }
 
+/*
+ * Basically just returns the filename, but with a twist.  The until the DNS
+ * resolver gives us a decent filename, we use a temporary one based on the
+ * IP address.  Once we have a decent filename, we copy everything from the
+ * temporary file to the final one.  So hopefully there is just a short
+ * window with IP filenames around and never should we lose data.
+ */
+static const char *copy_tmpfile(struct source_ip *sip)
+{
+	int fd, tmpfd;
+	const char *name, *tmpname;
+
+	name = sip->filename;
+	tmpname = sip->tmpfilename;
+	if (name && tmpname) {
+		char buf[4096];
+		ssize_t count;
+
+		fd = open(name, O_WRONLY | O_APPEND | O_CREAT, 0600);
+		if (fd < 0) {
+			syslog(LOG_ERR, "Unable to open \"%s\": %s", name,
+					strerror(errno));
+			goto out;
+		}
+		tmpfd = open(tmpname, O_RDONLY);
+		if (tmpfd < 0) {
+			syslog(LOG_ERR, "Unable to open \"%s\": %s", name,
+					strerror(errno));
+			close(fd);
+			goto out;
+		}
+		while ((count = read(tmpfd, buf, sizeof(buf))) > 0)
+			do_write(fd, buf, count);
+		close(tmpfd);
+		close(fd);
+		unlink(tmpname);
+		sip->tmpfilename = NULL;
+		free((void *)tmpname);
+	}
+out:
+	if (sip->tmpfilename)
+		return sip->tmpfilename;
+	if (sip->filename)
+		return sip->filename;
+	return NULL;
+}
+
 static void do_output(char *buf, int len, struct sockaddr_in *addr, socklen_t socklen)
 {
 	int fd;
 	const char *name;
 	struct source_ip *sip = get_source_ip(addr);
 
-	name = sip->filename;
+	name = copy_tmpfile(sip);
 	if (!name)
 		return;
 
@@ -636,8 +683,6 @@ static void dns_visitor(void *_sip, long unused, u32 ip, size_t unused2)
 	he = gethostbyaddr(&ip, 4, AF_INET);
 	if (!he)
 		return;
-	if (strcmp(he->h_name, sip->filename) == 0)
-		return;
 	new = strdup(he->h_name);
 	if (!new)
 		return;