Initial addition to CVS. These functions create an API for accessing the

dnsserver child process.

2 files changed, 240 insertions, 0 deletions

diff --git a/src/dnsclient.c b/src/dnsclient.c
new file mode 100644
index 0000000..7bf313d
--- /dev/null
+++ b/src/dnsclient.c
@@ -0,0 +1,208 @@
+/* $Id: dnsclient.c,v 1.1 2002-05-23 04:40:06 rjkaes Exp $
+ *
+ * Create the dnsserver child process, and then include functions to
+ * retrieve IP addresses or host names.  These functions are required
+ * since the traditional gethostbyaddr() and getaddrbyname() functions
+ * are not thread reentrant.  By spawning a child process the blocking
+ * has been moved outside the threads.
+ *
+ * Copyright (C) 2002  Robert James Kaes (rjkaes@flarenet.com)
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2, or (at your option) any
+ * later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+
+#include "tinyproxy.h"
+
+#include "dnsclient.h"
+#include "heap.h"
+#include "log.h"
+#include "network.h"
+#include "text.h"
+
+/*
+ * Static variable which holds the "dnsserver" process.
+ */
+static pid_t dnsserver_process;
+
+/*
+ * Hold the location of the Unix socket for client communication.
+ */
+static char* unix_socket_loc;
+
+/*
+ * Fork a copy of the "dnsserver" program.  Two arguments are used
+ * by this function: 'dnsserver_location' is the complete path to the
+ * dnsserver execuatable; 'path' is the absolute path used by the
+ * Unix socket.
+ */
+int
+start_dnsserver(const char* dnsserver_location, const char* path)
+{
+	int ret;
+
+	assert(dnsserver_location != NULL);
+	assert(path != NULL);
+
+	unix_socket_loc = safestrdup(path);
+
+	if ((dnsserver_process = fork()) == 0) {
+		/* Child process */
+		chdir("/");
+		umask(077);
+
+		close(0);
+		close(1);
+		close(2);
+
+		/* Start the "dnsserver" program */
+		ret = execl(dnsserver_location,
+			    dnsserver_location,
+			    path,
+			    NULL);
+		
+		if (ret < 0)
+			return -ENOEXEC;
+	}
+
+	/* Parent process */
+	return 0;
+}
+
+/*
+ * Stop the dnsserver process.
+ */
+int
+stop_dnsserver(void)
+{
+	kill(dnsserver_process, SIGTERM);
+	kill(dnsserver_process, SIGKILL);
+	unlink(unix_socket_loc);
+
+	return 0;
+}
+
+/*
+ * Returns a socket connected to the "dnsserver"
+ */
+int
+dns_connect(void)
+{
+	int dns;
+	struct sockaddr_un addr;
+
+	dns = socket(AF_LOCAL, SOCK_STREAM, 0);
+	if (dns < 0)
+		return -EIO;
+
+	memset(&addr, 0, sizeof(addr));
+	addr.sun_family = AF_LOCAL;
+	strcpy(addr.sun_path, unix_socket_loc);
+
+	if (connect(dns, (struct sockaddr *)&addr, sizeof(addr)) < 0)
+		return -EIO;
+	else
+		return dns;
+}
+
+/*
+ * Closes the connection to the "dnsserver"
+ */
+void
+dns_disconnect(int dns)
+{
+	assert(dns >= 0);
+
+	safe_write(dns, "$shutdown\n", 10);
+	close(dns);
+}
+
+/*
+ * Takes a dotted-decimal IP address and returns the host name in the
+ * buffer supplied by the caller.
+ *
+ * Returns:  0 if the buffer is filled correctly, or
+ *          -1 if there was an error
+ */
+int
+dns_gethostbyaddr(int dns, const char* ipaddr, char** hostname,
+		  size_t hostlen)
+{
+	char* buffer;
+	ssize_t len;
+	char *ptr;
+
+	assert(dns >= 0);
+	assert(ipaddr != NULL);
+	assert(hostname != NULL);
+	assert(hostlen > 0);
+
+	write_message(dns, "%s\n", ipaddr);
+	len = readline(dns, &buffer);
+	if (len < 0)
+		return len;
+	chomp(buffer, len);
+
+	if (strncmp(buffer, "$fail", 5) == 0) {
+		/* There was a problem. */
+		safefree(buffer);
+		return -ENOMSG;
+	}
+
+	ptr = strchr(buffer, ' ');
+	ptr++;
+
+	strlcpy(*hostname, ptr, hostlen);
+	
+	safefree(buffer);
+	return 0;
+}
+
+/*
+ * Takes a host name and returns an array of IP addresses.  The caller
+ * is responsible for freeing the 'addresses' memory block.
+ */
+int
+dns_getaddrbyname(int dns, const char* name, struct in_addr** addresses)
+{
+	char* buffer;
+	ssize_t len;
+	char *ptr;
+
+	assert(dns >= 0);
+	assert(name != NULL);
+	assert(addresses != NULL);
+
+	write_message(dns, "%s\n", name);
+	len = readline(dns, &buffer);
+	if (len < 0)
+		return len;
+	chomp(buffer, len);
+
+	if (strncmp(buffer, "$fail", 5) == 0) {
+		safefree(buffer);
+		return -ENOMSG;
+	}
+
+	ptr = strchr(buffer + 6, ' ');
+	if (ptr)
+		*ptr = '\0';
+	
+	*addresses = safemalloc(sizeof(struct in_addr));
+	if (!*addresses) {
+		safefree(buffer);
+		return -ENOMEM;
+	}
+
+	inet_aton(buffer + 6, *addresses);
+
+	safefree(buffer);
+	return 0;
+}
diff --git a/src/dnsclient.h b/src/dnsclient.h
new file mode 100644
index 0000000..32bad58
--- /dev/null
+++ b/src/dnsclient.h
@@ -0,0 +1,32 @@
+/* $Id: dnsclient.h,v 1.1 2002-05-23 04:40:06 rjkaes Exp $
+ *
+ * See 'dnsclient.c' for a detailed description.
+ *
+ * Copyright (C) 2002  Robert James Kaes (rjkaes@flarenet.com)
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2, or (at your option) any
+ * later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+
+#ifndef TINYPROXY_DNSCLIENT_H
+#define TINYPROXY_DNSCLIENT_H
+
+extern int start_dnsserver(const char* dnsserver_location, const char* path);
+extern int stop_dnsserver(void);
+
+extern int dns_connect(void);
+extern void dns_disconnect(int dns);
+
+extern int dns_gethostbyaddr(int dns, const char* ipaddr, char** hostname,
+			     size_t hostlen);
+extern int dns_getaddrbyname(int dns, const char* name,
+			     struct in_addr** addresses);
+
+#endif