[libslirp] Back-port icmp ping supportnetsim-devemu-prebuiltsemu-devemu-34-devemu-34-3-releaseemu-33-devaosp-emu-34-dev

Adapted from CL https://android-review.git.corp.google.com/c/platform/external/qemu/+/408506

BUG: 288280272

Change-Id: I6fc1f2a772ae3cd9aaf43a7dd43a8a58a40bd4c8
Signed-off-by: Weilun Du <wdu@google.com>

4 files changed, 156 insertions, 2 deletions

diff --git a/src/ip_icmp.c b/src/ip_icmp.c
index 6ae523c..8f3404f 100644
--- a/src/ip_icmp.c
+++ b/src/ip_icmp.c
@@ -117,7 +117,13 @@ static int icmp_send(struct socket *so, struct mbuf *m, int hlen)
         }
     }
     if (so->s == -1) {
+#ifndef WIN32
+        int res = ping_binary_send(so, m, hlen);
+        if (res != 0)
+           return -1;
+#else
         return -1;
+#endif
     }
     so->slirp->cb->register_poll_fd(so->s, so->slirp->opaque);
 
@@ -140,6 +146,11 @@ static int icmp_send(struct socket *so, struct mbuf *m, int hlen)
 
     slirp_insque(so, &so->slirp->icmp);
 
+#ifndef _WIN32
+    if (so->ping_pipe != NULL)
+        return 0;
+#endif
+
     if (sendto(so->s, m->m_data + hlen, m->m_len - hlen, 0,
                (struct sockaddr *)&addr, sizeof(addr)) == -1) {
         DEBUG_MISC("icmp_input icmp sendto tx errno = %d-%s", errno,
@@ -154,7 +165,14 @@ static int icmp_send(struct socket *so, struct mbuf *m, int hlen)
 void icmp_detach(struct socket *so)
 {
     so->slirp->cb->unregister_poll_fd(so->s, so->slirp->opaque);
+#ifndef WIN32
+    if (so->ping_pipe != NULL)
+        ping_binary_close(so);
+    else
+        closesocket(so->s);
+#else
     closesocket(so->s);
+#endif
     sofree(so);
 }
 
@@ -494,14 +512,22 @@ void icmp_receive(struct socket *so)
     int hlen = ip->ip_hl << 2;
     uint8_t error_code;
     struct icmp *icp;
-    int id, len;
+    int id, len = -1;
 
     m->m_data += hlen;
     m->m_len -= hlen;
     icp = mtod(m, struct icmp *);
 
     id = icp->icmp_id;
+
+#ifndef WIN32
+    if (so->ping_pipe != NULL)
+        len = ping_binary_recv(so, ip, icp);
+    else
+        len = recv(so->s, icp, M_ROOM(m), 0);
+#else
     len = recv(so->s, icp, M_ROOM(m), 0);
+#endif
 
     if (so->so_type == IPPROTO_IP) {
         if (len >= sizeof(struct ip)) {
diff --git a/src/ip_icmp.h b/src/ip_icmp.h
index 569a083..cb3d97c 100644
--- a/src/ip_icmp.h
+++ b/src/ip_icmp.h
@@ -165,4 +165,10 @@ void icmp_reflect(struct mbuf *);
 void icmp_receive(struct socket *so);
 void icmp_detach(struct socket *so);
 
+#ifndef WIN32
+int ping_binary_send(struct socket *so, struct mbuf *m, int hlen);
+int ping_binary_recv(struct socket *so, struct ip *ip, struct icmp *icp);
+void ping_binary_close(struct socket *so);
+#endif
+
 #endif
diff --git a/src/ip_icmp_ping.c b/src/ip_icmp_ping.c
new file mode 100644
index 0000000..a666248
--- /dev/null
+++ b/src/ip_icmp_ping.c
@@ -0,0 +1,118 @@
+/*
+ * Copyright (c) 2017
+ *	Google Inc.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ */
+
+/*
+ * Support ping using the system ping binary on Linux and Mac
+ * On Linux/Mac, icmp protocol requires the process to have system permission.
+ * Our emulator, by default, does not have system permission, so we have to
+ * resort to the built-in ping binary to handle icmp messages.
+ */
+
+#include "slirp.h"
+#include "ip_icmp.h"
+
+#include <fcntl.h>
+
+int ping_binary_send(struct socket* so, struct mbuf* m, int hlen) {
+    struct ip* ip = mtod(m, struct ip*);
+    const char* dest_ip_addr = inet_ntoa(ip->ip_dst);
+    char ping_cmd[1024];
+    sprintf(ping_cmd, "ping -c 1 -t %d %s 2>&1", ip->ip_ttl, dest_ip_addr);
+    FILE* p = popen(ping_cmd, "r");
+    if (!p) {
+        DEBUG_ERROR("popen failed for ping binary");
+        return -1;
+    }
+
+    so->ping_pipe = p;
+
+    // this is rather critical, otherwise emulator blocks when pinging
+    // an unreachable host
+    so->s = fileno(p);
+    fcntl(so->s, F_SETFL, O_NONBLOCK);
+
+    return 0;
+}
+
+/*
+ping -c 1 www.google.com
+PING www.google.com (172.217.6.36) 56(84) bytes of data.
+64 bytes from sfo03s08-in-f36.1e100.net (172.217.6.36): icmp_seq=1 ttl=57
+time=1.31 ms
+
+--- www.google.com ping statistics ---
+1 packets transmitted, 1 received, 0% packet loss, time 0ms
+rtt min/avg/max/mdev = 1.316/1.316/1.316/0.000 ms
+*/
+int ping_binary_recv(struct socket* so, struct ip* ip, struct icmp* icp) {
+    if (so == NULL || so->ping_pipe == NULL) {
+        return -1;
+    }
+
+    int seq = -1, ttl = -1;
+    char line[4096] = "";
+    char skip[4096] = "";
+    char skip2[4096] = "";
+    while (fgets(line, sizeof(line), so->ping_pipe)) {
+        char* p = strstr(line, "icmp_seq=");
+        if (p != NULL) {
+            p += strlen("icmp_seq=");
+            seq = atoi(p);
+        }
+        p = strstr(line, "ttl=");
+        if (p != NULL) {
+            p += strlen("ttl=");
+            ttl = atoi(p);
+        }
+
+        if (seq != -1 && ttl != -1) {
+            break;
+        }
+    }
+
+    if (seq != -1 && ttl != -1) {
+        ip->ip_ttl = ttl;
+        ip->ip_p = IPPROTO_ICMP;
+        icp->icmp_type = ICMP_ECHOREPLY;
+        icp->icmp_code = 0;
+        icp->icmp_cksum = 0;
+        // icp->icmp_seq = seq;
+        return sizeof(*icp);
+    }
+
+    return -1;
+}
+
+void ping_binary_close(struct socket* so) {
+    if (so != NULL && so->ping_pipe) {
+        pclose(so->ping_pipe);
+        so->ping_pipe = NULL;
+    }
+}
diff --git a/src/socket.h b/src/socket.h
index ca8c103..07ced57 100644
--- a/src/socket.h
+++ b/src/socket.h
@@ -39,7 +39,11 @@ union slirp_sockaddr {
 struct socket {
     struct socket *so_next, *so_prev; /* For a linked list of sockets */
 
-    int s; /* The actual socket */
+    int s;                           /* The actual socket or file descriptor of ping_pipe below */
+
+#ifndef WIN32
+  FILE *ping_pipe;                 /* the popen() stream for ping binary */
+#endif
     int s_aux; /* An auxiliary socket for miscellaneous use. Currently used to
                 * reserve OS ports in UNIX-to-inet translation. */
     struct gfwd_list *guestfwd;