Re: [PATCH] Verbose git-daemon logging

From

Petr Baudis <pasky@suse.cz>

Date

Sep 22, 2005, 09:25 UTC

Message-ID

<20050922092528.GB21019@pasky.or.cz>

In-Reply-To

<7vwtl9mqm5.fsf@assigned-by-dhcp.cox.net>

> > +static void logreport(const char *err, va_list params)
> > +{
> > +	/* We should do a single write so that it is atomic and output
> > +	 * of several threads does not get intermangled. */
> 
> "threads"?  Nevertheless yes it is nicer to do a single write.

> > +	char buf[1024];
> > +	int buflen;
> > +
> > +	buflen = snprintf(buf, 1024, "[%d] ", getpid());
> 
> sizeof(buf)?

Ack.

> > +	buflen += vsnprintf(buf + buflen, 1024 - buflen, err, params);
> 
> vsnprintf() would return number of characters that would have
> been written if the buffer were sufficiently long, so buflen can
> grow outside buf[].  I could ask for a deeeeeeeeeeep directory
> to git-daemon, have it say "Request for 'diiiiiiiiiiiiii....r'",
> and have this code
> 
> > +	buf[buflen++] = '\n';
> > +	buf[buflen] = '\0';
> 
> overwrite the stack with these two bytes; overwriting with
> constant bytes may or may not be exploitable, though.

Whoops.

> Also the man page says glibc 2.0.6 returned -1 upon output
> truncation.  Do we care?

> > @@ -212,6 +275,9 @@ static void child_handler(int signo)
> >  			unsigned reaped = children_reaped;
> >  			dead_child[reaped % MAX_CHILDREN] = pid;
> >  			children_reaped = reaped + 1;
> > +			/* XXX: Custom logging, since we don't wanna getpid() */
> > +			if (verbose)
> > +				fprintf(stderr, "[%d] Disconnected\n", pid);
> 
> "we don't wanna getpid()" because the guy reporting is the
> parent?  I would presume knowing parent PID would also useful,
> so maybe we could say "[1012] child 1014 disconnected\n" for
> parent 1012 reaping chilid 1014? 

Fixed up patch follows.

--

[PATCH] Verbose git-daemon logging

Signed-off-by: Petr Baudis <pasky@suse.cz>

 daemon.c |   87 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++---
 1 files changed, 83 insertions(+), 4 deletions(-)

diff --git a/daemon.c b/daemon.c
--- a/daemon.c
+++ b/daemon.c
@@ -6,13 +6,63 @@
 #include <sys/time.h>
 #include <netdb.h>
 #include <netinet/in.h>
+#include <arpa/inet.h>
+
+static int verbose;
+
+static const char daemon_usage[] = "git-daemon [--verbose] [--inetd | --port=n]";
+
+
+static void logreport(const char *err, va_list params)
+{
+	/* We should do a single write so that it is atomic and output
+	 * of several processes does not get intermangled. */
+	char buf[1024];
+	int buflen;
+	int maxlen, msglen;
+
+	buflen = snprintf(buf, sizeof(buf), "[%d] ", getpid());
+
+	maxlen = sizeof(buf) - buflen - 1;
+	msglen = vsnprintf(buf + buflen, maxlen, err, params);
+	if (msglen > maxlen)
+		msglen = maxlen;
+	else if (msglen < 0)
+		msglen = -1; /* Protect against weird return values. */
+	buflen += msglen;
+
+	buf[buflen++] = '\n';
+	buf[buflen] = '\0';
+
+	fputs(buf, stderr);
+}
+
+void logerror(const char *err, ...)
+{
+	va_list params;
+	va_start(params, err);
+	logreport(err, params);
+	va_end(params);
+}
+
+void lognotice(const char *err, ...)
+{
+	va_list params;
+	if (!verbose)
+		return;
+	va_start(params, err);
+	logreport(err, params);
+	va_end(params);
+}
 
-static const char daemon_usage[] = "git-daemon [--inetd | --port=n]";
 
 static int upload(char *dir, int dirlen)
 {
-	if (chdir(dir) < 0)
+	lognotice("Request for '%s'", dir);
+	if (chdir(dir) < 0) {
+		logerror("Cannot chdir('%s'): %s", dir, strerror(errno));
 		return -1;
+	}
 	chdir(".git");
 
 	/*
@@ -24,8 +74,10 @@ static int upload(char *dir, int dirlen)
 	 */
 	if (access("git-daemon-export-ok", F_OK) ||
 	    access("objects/00", X_OK) ||
-	    access("HEAD", R_OK))
+	    access("HEAD", R_OK)) {
+		logerror("Not a valid gitd-enabled repository: '%s'", dir);
 		return -1;
+	}
 
 	/*
 	 * We'll ignore SIGTERM from now on, we have a
@@ -51,7 +103,7 @@ static int execute(void)
 	if (!strncmp("git-upload-pack /", line, 17))
 		return upload(line + 16, len - 16);
 
-	fprintf(stderr, "got bad connection '%s'\n", line);
+	logerror("Protocol error: '%s'", line);
 	return -1;
 }
 
@@ -181,6 +233,8 @@ static void check_max_connections(void)
 static void handle(int incoming, struct sockaddr *addr, int addrlen)
 {
 	pid_t pid = fork();
+	char addrbuf[256] = "";
+	int port = -1;
 
 	if (pid) {
 		unsigned idx;
@@ -200,6 +254,24 @@ static void handle(int incoming, struct 
 	dup2(incoming, 0);
 	dup2(incoming, 1);
 	close(incoming);
+
+	if (addr->sa_family == AF_INET) {
+		struct sockaddr_in *sin_addr = (void *) addr;
+		inet_ntop(AF_INET, &sin_addr->sin_addr, addrbuf, sizeof(addrbuf));
+		port = sin_addr->sin_port;
+
+	} else if (addr->sa_family == AF_INET6) {
+		struct sockaddr_in6 *sin6_addr = (void *) addr;
+
+		char *buf = addrbuf;
+		*buf++ = '['; *buf = '\0'; /* stpcpy() is cool */
+		inet_ntop(AF_INET6, &sin6_addr->sin6_addr, buf, sizeof(addrbuf) - 1);
+		strcat(buf, "]");
+
+		port = sin6_addr->sin6_port;
+	}
+	lognotice("Connection from %s:%d", addrbuf, port);
+
 	exit(execute());
 }
 
@@ -212,6 +284,9 @@ static void child_handler(int signo)
 			unsigned reaped = children_reaped;
 			dead_child[reaped % MAX_CHILDREN] = pid;
 			children_reaped = reaped + 1;
+			/* XXX: Custom logging, since we don't wanna getpid() */
+			if (verbose)
+				fprintf(stderr, "[%d] Disconnected\n", pid);
 			continue;
 		}
 		break;
@@ -349,6 +424,10 @@ int main(int argc, char **argv)
 			inetd_mode = 1;
 			continue;
 		}
+		if (!strcmp(arg, "--verbose")) {
+			verbose = 1;
+			continue;
+		}
 
 		usage(daemon_usage);
 	}

-- 
				Petr "Pasky" Baudis
Stuff: http://pasky.or.cz/
VI has two modes: the one in which it beeps and the one in which
it doesn't.