Add network status check for AWG/WG protocol

client/platforms/linux/linuxpingsender.cpp

@@ -0,0 +1,185 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "linuxpingsender.h"
+
+#include <arpa/inet.h>
+#include <errno.h>
+#include <linux/filter.h>
+#include <netinet/in.h>
+#include <netinet/ip.h>
+#include <netinet/ip_icmp.h>
+#include <sys/socket.h>
+#include <unistd.h>
+
+#include <QSocketNotifier>
+#include <QtEndian>
+
+#include "leakdetector.h"
+#include "logger.h"
+#include "qhostaddress.h"
+
+namespace {
+Logger logger("LinuxPingSender");
+}
+
+int LinuxPingSender::createSocket() {
+  // Try creating an ICMP socket. This would be the ideal choice, but it can
+  // fail depending on the kernel config (see: sys.net.ipv4.ping_group_range)
+  m_socket = socket(AF_INET, SOCK_DGRAM, IPPROTO_ICMP);
+  if (m_socket >= 0) {
+    m_ident = 0;
+    return m_socket;
+  }
+  if ((errno != EPERM) && (errno != EACCES)) {
+    return -1;
+  }
+
+  // As a fallback, create a raw socket, which requires root permissions
+  // or CAP_NET_RAW to be granted to the VPN client.
+  m_socket = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP);
+  if (m_socket < 0) {
+    return -1;
+  }
+  m_ident = getpid() & 0xffff;
+
+  // Attach a BPF filter to discard everything but replies to our echo.
+  struct sock_filter bpf_prog[] = {
+      BPF_STMT(BPF_LDX | BPF_B | BPF_MSH, 0), /* Skip IP header. */
+      BPF_STMT(BPF_LD | BPF_H | BPF_IND, 4),  /* Load icmp echo ident */
+      BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, m_ident, 1, 0), /* Ours? */
+      BPF_STMT(BPF_RET | BPF_K, 0), /* Unexpected identifier. Reject. */
+      BPF_STMT(BPF_LD | BPF_B | BPF_IND, 0), /* Load icmp type */
+      BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, ICMP_ECHOREPLY, 1, 0), /* Echo? */
+      BPF_STMT(BPF_RET | BPF_K, 0),   /* Unexpected type. Reject. */
+      BPF_STMT(BPF_RET | BPF_K, ~0U), /* Packet passes the filter. */
+  };
+  struct sock_fprog filter = {
+      .len = sizeof(bpf_prog) / sizeof(struct sock_filter),
+      .filter = bpf_prog,
+  };
+  setsockopt(m_socket, SOL_SOCKET, SO_ATTACH_FILTER, &filter, sizeof(filter));
+
+  return m_socket;
+}
+
+LinuxPingSender::LinuxPingSender(const QHostAddress& source, QObject* parent)
+    : PingSender(parent) {
+  MZ_COUNT_CTOR(LinuxPingSender);
+
+  logger.debug() << "LinuxPingSender(" + logger.sensitive(source.toString()) +
+                        ") created";
+
+  m_socket = createSocket();
+  if (m_socket < 0) {
+    logger.error() << "Socket creation error: " << strerror(errno);
+    return;
+  }
+
+  quint32 ipv4addr = INADDR_ANY;
+  if (!source.isNull()) {
+    ipv4addr = source.toIPv4Address();
+  }
+  struct sockaddr_in addr;
+  memset(&addr, 0, sizeof addr);
+  addr.sin_family = AF_INET;
+  addr.sin_addr.s_addr = qToBigEndian<quint32>(ipv4addr);
+
+  if (bind(m_socket, (struct sockaddr*)&addr, sizeof(addr)) != 0) {
+    close(m_socket);
+    m_socket = -1;
+    logger.error() << "bind error:" << strerror(errno);
+    return;
+  }
+
+  m_notifier = new QSocketNotifier(m_socket, QSocketNotifier::Read, this);
+  if (m_ident) {
+    connect(m_notifier, &QSocketNotifier::activated, this,
+            &LinuxPingSender::rawSocketReady);
+  } else {
+    connect(m_notifier, &QSocketNotifier::activated, this,
+            &LinuxPingSender::icmpSocketReady);
+  }
+}
+
+LinuxPingSender::~LinuxPingSender() {
+  MZ_COUNT_DTOR(LinuxPingSender);
+  if (m_socket >= 0) {
+    close(m_socket);
+  }
+}
+
+void LinuxPingSender::sendPing(const QHostAddress& dest, quint16 sequence) {
+  quint32 ipv4dest = dest.toIPv4Address();
+  struct sockaddr_in addr;
+  memset(&addr, 0, sizeof(addr));
+  addr.sin_family = AF_INET;
+  addr.sin_addr.s_addr = qToBigEndian<quint32>(ipv4dest);
+
+  struct icmphdr packet;
+  memset(&packet, 0, sizeof(packet));
+  packet.type = ICMP_ECHO;
+  packet.un.echo.id = htons(m_ident);
+  packet.un.echo.sequence = htons(sequence);
+  packet.checksum = inetChecksum(&packet, sizeof(packet));
+
+  int rc = sendto(m_socket, &packet, sizeof(packet), 0, (struct sockaddr*)&addr,
+                  sizeof(addr));
+  if (rc < 0) {
+    logger.error() << "failed to send:" << strerror(errno);
+    if (errno == ENETUNREACH) {
+        emit criticalPingError();
+    }
+  }
+}
+
+void LinuxPingSender::icmpSocketReady() {
+  socklen_t slen = 0;
+  unsigned char data[2048];
+  int rc = recvfrom(m_socket, data, sizeof(data), MSG_DONTWAIT, NULL, &slen);
+  if (rc <= 0) {
+    logger.error() << "recvfrom failed:" << strerror(errno);
+    return;
+  }
+
+  struct icmphdr packet;
+  if (rc >= (int)sizeof(packet)) {
+    memcpy(&packet, data, sizeof(packet));
+    if (packet.type == ICMP_ECHOREPLY) {
+      emit recvPing(htons(packet.un.echo.sequence));
+    }
+  }
+}
+
+void LinuxPingSender::rawSocketReady() {
+  socklen_t slen = 0;
+  unsigned char data[2048];
+  int rc = recvfrom(m_socket, data, sizeof(data), MSG_DONTWAIT, NULL, &slen);
+  if (rc <= 0) {
+    logger.error() << "recvfrom failed:" << strerror(errno);
+    return;
+  }
+
+  // Check the IP header
+  const struct iphdr* ip = (struct iphdr*)data;
+  int iphdrlen = ip->ihl * 4;
+  if (rc < iphdrlen || iphdrlen < (int)sizeof(struct iphdr)) {
+    logger.error() << "malformed IP packet:" << strerror(errno);
+    return;
+  }
+
+  // Check the ICMP packet
+  struct icmphdr packet;
+  if (inetChecksum(data + iphdrlen, rc - iphdrlen) != 0) {
+    logger.warning() << "invalid checksum";
+    return;
+  }
+  if (rc >= (iphdrlen + (int)sizeof(packet))) {
+    memcpy(&packet, data + iphdrlen, sizeof(packet));
+    quint16 id = htons(m_ident);
+    if ((packet.type == ICMP_ECHOREPLY) && (packet.un.echo.id == id)) {
+      emit recvPing(htons(packet.un.echo.sequence));
+    }
+  }
+}