libc_lwip_nic_dhcp: provide '/etc/resolv.conf'
With this patch, the 'libc_lwip_nic_dhcp' plugin provides the DNS server address acquired by lwIP via DHCP in the file '/etc/resolv.conf'. This feature can be disabled from the config file: <libc resolv="no" /> The static network interface configuration attributes are now also a part of the '<libc>' config node: <libc ip_addr="..." netmask="..." gateway="..." /> Fixes #731.
This commit is contained in:
Christian Prochaska
Norman Feske
parent
d184599a89
commit
339a0354ce
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@ -1,4 +1,4 @@
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SRC_CC = init.cc
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SRC_CC = init.cc plugin.cc
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vpath %.cc $(REP_DIR)/src/lib/libc_lwip_nic_dhcp
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@ -109,7 +109,7 @@ mimetype.assign = (
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<start name="lighttpd">
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<resource name="RAM" quantum="256M" />
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<config>
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<interface ip_addr="10.0.2.55" netmask="255.255.255.0" gateway="10.0.2.1"/>
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<libc ip_addr="10.0.2.55" netmask="255.255.255.0" gateway="10.0.2.1"/>
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<arg value="lighttpd" />
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<arg value="-f" />
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<arg value="/etc/lighttpd/lighttpd.conf" />
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@ -27,12 +27,15 @@ extern "C" {
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extern void create_lwip_plugin();
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extern void create_etc_resolv_conf_plugin();
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void __attribute__((constructor)) init_nic_dhcp(void)
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{
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PDBG("init_nic_dhcp()\n");
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bool provide_etc_resolv_conf = true;
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char ip_addr_str[16] = {0};
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char netmask_str[16] = {0};
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char gateway_str[16] = {0};
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@ -40,50 +43,57 @@ void __attribute__((constructor)) init_nic_dhcp(void)
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genode_int32_t ip_addr = 0;
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genode_int32_t netmask = 0;
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genode_int32_t gateway = 0;
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try {
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Genode::Xml_node interface_node = Genode::config()->xml_node().sub_node("interface");
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Genode::Xml_node libc_node = Genode::config()->xml_node().sub_node("libc");
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try {
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interface_node.attribute("ip_addr").value(ip_addr_str, sizeof(ip_addr_str));
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}
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catch(Genode::Xml_node::Nonexistent_attribute)
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{
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PERR("Missing \"ip_addr\" attribute. Ignore interface config.");
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throw;
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}
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if (libc_node.attribute("resolv").has_value("no"))
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provide_etc_resolv_conf = false;
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} catch(...) { }
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try {
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interface_node.attribute("netmask").value(netmask_str, sizeof(netmask_str));
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}
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catch(Genode::Xml_node::Nonexistent_attribute)
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{
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PERR("Missing \"netmask\" attribute. Ignore interface config.");
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throw;
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}
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libc_node.attribute("ip_addr").value(ip_addr_str, sizeof(ip_addr_str));
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} catch(...) { }
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try {
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interface_node.attribute("gateway").value(gateway_str, sizeof(gateway_str));
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}
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catch(Genode::Xml_node::Nonexistent_attribute)
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{
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PERR("Missing \"gateway\" attribute. Ignore interface config.");
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throw;
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}
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PDBG("interface: ip_addr=%s netmask=%s gateway=%s ",
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libc_node.attribute("netmask").value(netmask_str, sizeof(netmask_str));
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} catch(...) { }
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try {
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libc_node.attribute("gateway").value(gateway_str, sizeof(gateway_str));
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} catch(...) { }
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/* either none or all 3 interface attributes must exist */
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if ((strlen(ip_addr_str) != 0) ||
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(strlen(netmask_str) != 0) ||
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(strlen(gateway_str) != 0)) {
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if (strlen(ip_addr_str) == 0) {
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PERR("Missing \"ip_addr\" attribute. Ignoring network interface config.");
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throw Genode::Xml_node::Nonexistent_attribute();
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} else if (strlen(netmask_str) == 0) {
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PERR("Missing \"netmask\" attribute. Ignoring network interface config.");
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throw Genode::Xml_node::Nonexistent_attribute();
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} else if (strlen(gateway_str) == 0) {
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PERR("Missing \"gateway\" attribute. Ignoring network interface config.");
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throw Genode::Xml_node::Nonexistent_attribute();
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}
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} else
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throw -1;
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PDBG("static network interface: ip_addr=%s netmask=%s gateway=%s ",
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ip_addr_str, netmask_str, gateway_str
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);
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genode_int32_t ip, nm, gw;
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genode_uint32_t ip, nm, gw;
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ip = inet_addr(ip_addr_str);
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nm = inet_addr(netmask_str);
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gw = inet_addr(gateway_str);
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if (ip == INADDR_NONE || nm == INADDR_NONE || gw == INADDR_NONE) {
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PERR("Invalid interface config.");
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throw;
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PERR("Invalid network interface config.");
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throw -1;
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} else {
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ip_addr = ip;
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netmask = nm;
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@ -102,4 +112,7 @@ void __attribute__((constructor)) init_nic_dhcp(void)
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} catch (Genode::Parent::Service_denied) {
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/* ignore for now */
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}
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if (provide_etc_resolv_conf)
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create_etc_resolv_conf_plugin();
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}
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@ -0,0 +1,234 @@
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/*
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* \brief Libc plugin providing lwIP's DNS server address in the
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* '/etc/resolv.conf' file
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* \author Christian Prochaska
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* \date 2013-05-02
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*/
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/*
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* Copyright (C) 2013 Genode Labs GmbH
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*
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* This file is part of the Genode OS framework, which is distributed
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* under the terms of the GNU General Public License version 2.
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*/
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/* lwip includes */
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#include <lwip/err.h>
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#include <lwip/ip_addr.h>
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#include <lwip/dns.h>
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/* fix redefinition warnings */
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#undef LITTLE_ENDIAN
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#undef BIG_ENDIAN
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#undef BYTE_ORDER
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/* libc plugin interface */
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#include <libc-plugin/plugin.h>
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#include <libc-plugin/fd_alloc.h>
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/* libc includes */
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#include <errno.h>
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#include <fcntl.h>
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#include <stdio.h>
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#include <string.h>
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/* Genode includes */
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#include <base/env.h>
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#include <util/misc_math.h>
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namespace {
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class Plugin_context : public Libc::Plugin_context
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{
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private:
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int _status_flags;
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off_t _seek_offset;
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public:
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Plugin_context() : _status_flags(0), _seek_offset(0) { }
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/**
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* Set/get file status status flags
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*/
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void status_flags(int flags) { _status_flags = flags; }
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int status_flags() { return _status_flags; }
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/**
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* Set seek offset
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*/
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void seek_offset(size_t seek_offset) { _seek_offset = seek_offset; }
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/**
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* Return seek offset
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*/
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off_t seek_offset() const { return _seek_offset; }
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/**
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* Advance current seek position by 'incr' number of bytes
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*/
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void advance_seek_offset(size_t incr)
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{
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_seek_offset += incr;
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}
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void infinite_seek_offset()
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{
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_seek_offset = ~0;
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}
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};
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static inline Plugin_context *context(Libc::File_descriptor *fd)
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{
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return static_cast<Plugin_context *>(fd->context);
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}
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class Plugin : public Libc::Plugin
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{
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private:
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/**
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* File name this plugin feels responsible for
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*/
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static char const *_file_name() { return "/etc/resolv.conf"; }
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const char *_file_content()
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{
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static char result[32];
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ip_addr_t nameserver_ip = dns_getserver(0);
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snprintf(result, sizeof(result), "nameserver %s\n",
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ipaddr_ntoa(&nameserver_ip));
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return result;
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}
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::off_t _file_size(Libc::File_descriptor *fd)
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{
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struct stat stat_buf;
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if (fstat(fd, &stat_buf) == -1)
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return -1;
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return stat_buf.st_size;
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}
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public:
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/**
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* Constructor
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*/
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Plugin() { }
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bool supports_stat(const char *path)
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{
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return (Genode::strcmp(path, "/etc") == 0) ||
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(Genode::strcmp(path, _file_name()) == 0);
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}
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bool supports_open(const char *path, int flags)
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{
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return (Genode::strcmp(path, _file_name()) == 0);
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}
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Libc::File_descriptor *open(const char *pathname, int flags)
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{
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Plugin_context *context = new (Genode::env()->heap()) Plugin_context;
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context->status_flags(flags);
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return Libc::file_descriptor_allocator()->alloc(this, context);
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}
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int close(Libc::File_descriptor *fd)
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{
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Genode::destroy(Genode::env()->heap(), context(fd));
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Libc::file_descriptor_allocator()->free(fd);
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return 0;
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}
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int stat(const char *path, struct stat *buf)
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{
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if (buf) {
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Genode::memset(buf, 0, sizeof(struct stat));
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if (Genode::strcmp(path, "/etc") == 0)
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buf->st_mode = S_IFDIR;
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else if (Genode::strcmp(path, _file_name()) == 0) {
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buf->st_mode = S_IFREG;
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buf->st_size = strlen(_file_content()) + 1;
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} else {
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errno = ENOENT;
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return -1;
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}
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}
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return 0;
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}
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int fstat(Libc::File_descriptor *fd, struct stat *buf)
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{
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if (buf) {
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Genode::memset(buf, 0, sizeof(struct stat));
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buf->st_mode = S_IFREG;
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buf->st_size = strlen(_file_content()) + 1;
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}
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return 0;
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}
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::off_t lseek(Libc::File_descriptor *fd, ::off_t offset, int whence)
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{
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switch (whence) {
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case SEEK_SET:
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context(fd)->seek_offset(offset);
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return offset;
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case SEEK_CUR:
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context(fd)->advance_seek_offset(offset);
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return context(fd)->seek_offset();
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case SEEK_END:
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if (offset != 0) {
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errno = EINVAL;
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return -1;
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}
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context(fd)->infinite_seek_offset();
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return _file_size(fd);
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default:
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errno = EINVAL;
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return -1;
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}
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}
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ssize_t read(Libc::File_descriptor *fd, void *buf, ::size_t count)
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{
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::off_t seek_offset = context(fd)->seek_offset();
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if (seek_offset >= _file_size(fd))
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return 0;
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const char *content = _file_content();
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count = Genode::min((::off_t)count, _file_size(fd) - seek_offset);
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memcpy(buf, &content[seek_offset], count);
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context(fd)->advance_seek_offset(count);
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return count;
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}
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int fcntl(Libc::File_descriptor *fd, int cmd, long arg)
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{
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switch (cmd) {
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case F_GETFL: return context(fd)->status_flags();
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default: PERR("fcntl(): command %d not supported", cmd); return -1;
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}
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}
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};
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} /* unnamed namespace */
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void create_etc_resolv_conf_plugin()
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{
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static Plugin plugin;
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}
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