[Qemu-devel] [PATCHv7 2/9] slirp: Adding ICMPv6 error sending

[Samuel Thibault <samuel.thibault@ens-lyon.org>]

From: Yann Bordenave <meow@meowstars.org>

Disambiguation : icmp_error is renamed into icmp_send_error, since it
doesn't manage errors, but only sends ICMP Error messages.

Adding icmp6_send_error to send ICMPv6 Error messages. This function is
simpler than the v4 version.
Adding some calls in various functions to send ICMP errors, when a
received packet is too big, or when its hop limit is 0.

Signed-off-by: Yann Bordenave <meow@meowstars.org>
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
---
 slirp/ip6_icmp.c  | 60 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 slirp/ip6_icmp.h  | 10 ++++++++++
 slirp/ip6_input.c | 15 ++++++++------
 slirp/ip_icmp.c   | 12 +++++------
 slirp/ip_icmp.h   |  4 ++--
 slirp/ip_input.c  |  8 ++++----
 slirp/socket.c    |  4 ++--
 slirp/tcp_input.c |  2 +-
 slirp/udp.c       |  3 ++-
 9 files changed, 96 insertions(+), 22 deletions(-)

diff --git a/slirp/ip6_icmp.c b/slirp/ip6_icmp.c
index 13f89af..41e034b 100644
--- a/slirp/ip6_icmp.c
+++ b/slirp/ip6_icmp.c
@@ -67,6 +67,66 @@ static void icmp6_send_echoreply(struct mbuf *m, Slirp *slirp, struct ip6 *ip,
     ip6_output(NULL, t, 0);
 }
 
+void icmp6_send_error(struct mbuf *m, uint8_t type, uint8_t code)
+{
+    Slirp *slirp = m->slirp;
+    struct mbuf *t = m_get(slirp);
+    struct ip6 *ip = mtod(m, struct ip6 *);
+
+    char addrstr[INET6_ADDRSTRLEN];
+    DEBUG_CALL("icmp_send_error");
+    DEBUG_ARGS((dfd, " type = %d, code = %d\n", type, code));
+
+    /* IPv6 packet */
+    struct ip6 *rip = mtod(t, struct ip6 *);
+    rip->ip_src = (struct in6_addr)LINKLOCAL_ADDR;
+    if (in6_multicast(ip->ip_src) || in6_unspecified(ip->ip_src)) {
+        /* TODO icmp error? */
+        return;
+    }
+    rip->ip_dst = ip->ip_src;
+    inet_ntop(AF_INET6, &rip->ip_dst, addrstr, INET6_ADDRSTRLEN);
+    DEBUG_ARG("target = %s", addrstr);
+
+    rip->ip_nh = IPPROTO_ICMPV6;
+    const int error_data_len = min(m->m_len,
+            IF_MTU - (sizeof(struct ip6) + ICMP6_ERROR_MINLEN));
+    rip->ip_pl = htons(ICMP6_ERROR_MINLEN + error_data_len);
+    t->m_len = sizeof(struct ip6) + ntohs(rip->ip_pl);
+
+    /* ICMPv6 packet */
+    t->m_data += sizeof(struct ip6);
+    struct icmp6 *ricmp = mtod(t, struct icmp6 *);
+    ricmp->icmp6_type = type;
+    ricmp->icmp6_code = code;
+    ricmp->icmp6_cksum = 0;
+
+    switch (type) {
+    case ICMP6_UNREACH:
+    case ICMP6_TIMXCEED:
+        ricmp->icmp6_err.unused = 0;
+        break;
+    case ICMP6_TOOBIG:
+        ricmp->icmp6_err.mtu = htonl(IF_MTU);
+        break;
+    case ICMP6_PARAMPROB:
+        /* TODO: Handle this case */
+        break;
+    default:
+        g_assert_not_reached();
+        break;
+    }
+    t->m_data += ICMP6_ERROR_MINLEN;
+    memcpy(t->m_data, m->m_data, error_data_len);
+
+    /* Checksum */
+    t->m_data -= ICMP6_ERROR_MINLEN;
+    t->m_data -= sizeof(struct ip6);
+    ricmp->icmp6_cksum = ip6_cksum(t);
+
+    ip6_output(NULL, t, 0);
+}
+
 /*
  * Process a NDP message
  */
diff --git a/slirp/ip6_icmp.h b/slirp/ip6_icmp.h
index 1ae003b..f47c29f 100644
--- a/slirp/ip6_icmp.h
+++ b/slirp/ip6_icmp.h
@@ -22,6 +22,12 @@ struct icmp6_echo { /* Echo Messages */
     uint16_t seq_num;
 };
 
+union icmp6_error_body {
+    uint32_t unused;
+    uint32_t pointer;
+    uint32_t mtu;
+};
+
 /*
  * NDP Messages
  */
@@ -85,6 +91,7 @@ struct icmp6 {
     uint8_t     icmp6_code;         /* type sub code */
     uint16_t    icmp6_cksum;        /* ones complement cksum of struct */
     union {
+        union icmp6_error_body error_body;
         struct icmp6_echo echo;
         struct ndp_rs ndp_rs;
         struct ndp_ra ndp_ra;
@@ -92,6 +99,7 @@ struct icmp6 {
         struct ndp_na ndp_na;
         struct ndp_redirect ndp_redirect;
     } icmp6_body;
+#define icmp6_err icmp6_body.error_body
 #define icmp6_echo icmp6_body.echo
 #define icmp6_nrs icmp6_body.ndp_rs
 #define icmp6_nra icmp6_body.ndp_ra
@@ -101,6 +109,7 @@ struct icmp6 {
 } QEMU_PACKED;
 
 #define ICMP6_MINLEN    4
+#define ICMP6_ERROR_MINLEN  8
 #define ICMP6_ECHO_MINLEN   8
 #define ICMP6_NDP_RS_MINLEN 8
 #define ICMP6_NDP_RA_MINLEN 16
@@ -238,6 +247,7 @@ struct ndpopt {
 void icmp6_init(Slirp *slirp);
 void icmp6_cleanup(Slirp *slirp);
 void icmp6_input(struct mbuf *);
+void icmp6_send_error(struct mbuf *m, uint8_t type, uint8_t code);
 void ndp_send_ra(Slirp *slirp);
 void ndp_send_ns(Slirp *slirp, struct in6_addr addr);
 
diff --git a/slirp/ip6_input.c b/slirp/ip6_input.c
index e1e6229..828f47c 100644
--- a/slirp/ip6_input.c
+++ b/slirp/ip6_input.c
@@ -33,7 +33,7 @@ void ip6_input(struct mbuf *m)
     DEBUG_ARG("m_len = %d", m->m_len);
 
     if (m->m_len < sizeof(struct ip6)) {
-        return;
+        goto bad;
     }
 
     ip6 = mtod(m, struct ip6 *);
@@ -42,9 +42,14 @@ void ip6_input(struct mbuf *m)
         goto bad;
     }
 
+    if (ntohs(ip6->ip_pl) > IF_MTU) {
+        icmp6_send_error(m, ICMP6_TOOBIG, 0);
+        goto bad;
+    }
+
     /* check ip_ttl for a correct ICMP reply */
     if (ip6->ip_hl == 0) {
-        /*icmp_error(m, ICMP_TIMXCEED,ICMP_TIMXCEED_INTRANS, 0,"ttl");*/
+        icmp6_send_error(m, ICMP6_TIMXCEED, ICMP6_TIMXCEED_INTRANS);
         goto bad;
     }
 
@@ -52,14 +57,12 @@ void ip6_input(struct mbuf *m)
      * Switch out to protocol's input routine.
      */
     switch (ip6->ip_nh) {
-#if 0
     case IPPROTO_TCP:
-        tcp_input(m, hlen, (struct socket *)NULL);
+        icmp6_send_error(m, ICMP6_UNREACH, ICMP6_UNREACH_NO_ROUTE);
         break;
     case IPPROTO_UDP:
-        udp_input(m, hlen);
+        icmp6_send_error(m, ICMP6_UNREACH, ICMP6_UNREACH_NO_ROUTE);
         break;
-#endif
     case IPPROTO_ICMPV6:
         icmp6_input(m);
         break;
diff --git a/slirp/ip_icmp.c b/slirp/ip_icmp.c
index ace3982..590dada 100644
--- a/slirp/ip_icmp.c
+++ b/slirp/ip_icmp.c
@@ -38,7 +38,7 @@
 /* Be nice and tell them it's just a pseudo-ping packet */
 static const char icmp_ping_msg[] = "This is a pseudo-PING packet used by Slirp to emulate ICMP ECHO-REQUEST packets.\n";
 
-/* list of actions for icmp_error() on RX of an icmp message */
+/* list of actions for icmp_send_error() on RX of an icmp message */
 static const int icmp_flush[19] = {
 /*  ECHO REPLY (0)  */   0,
 		         1,
@@ -101,7 +101,7 @@ static int icmp_send(struct socket *so, struct mbuf *m, int hlen)
                (struct sockaddr *)&addr, sizeof(addr)) == -1) {
         DEBUG_MISC((dfd, "icmp_input icmp sendto tx errno = %d-%s\n",
                     errno, strerror(errno)));
-        icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_NET, 0, strerror(errno));
+        icmp_send_error(m, ICMP_UNREACH, ICMP_UNREACH_NET, 0, strerror(errno));
         icmp_detach(so);
     }
 
@@ -189,7 +189,7 @@ icmp_input(struct mbuf *m, int hlen)
 		(struct sockaddr *)&addr, sizeof(addr)) == -1) {
 	DEBUG_MISC((dfd,"icmp_input udp sendto tx errno = %d-%s\n",
 		    errno,strerror(errno)));
-	icmp_error(m, ICMP_UNREACH,ICMP_UNREACH_NET, 0,strerror(errno));
+	icmp_send_error(m, ICMP_UNREACH, ICMP_UNREACH_NET, 0, strerror(errno));
 	udp_detach(so);
       }
     } /* if ip->ip_dst.s_addr == alias_addr.s_addr */
@@ -235,7 +235,7 @@ end_error:
 
 #define ICMP_MAXDATALEN (IP_MSS-28)
 void
-icmp_error(struct mbuf *msrc, u_char type, u_char code, int minsize,
+icmp_send_error(struct mbuf *msrc, u_char type, u_char code, int minsize,
            const char *message)
 {
   unsigned hlen, shlen, s_ip_len;
@@ -243,7 +243,7 @@ icmp_error(struct mbuf *msrc, u_char type, u_char code, int minsize,
   register struct icmp *icp;
   register struct mbuf *m;
 
-  DEBUG_CALL("icmp_error");
+  DEBUG_CALL("icmp_send_error");
   DEBUG_ARG("msrc = %p", msrc);
   DEBUG_ARG("msrc_len = %d", msrc->m_len);
 
@@ -433,7 +433,7 @@ void icmp_receive(struct socket *so)
         }
         DEBUG_MISC((dfd, " udp icmp rx errno = %d-%s\n", errno,
                     strerror(errno)));
-        icmp_error(so->so_m, ICMP_UNREACH, error_code, 0, strerror(errno));
+        icmp_send_error(so->so_m, ICMP_UNREACH, error_code, 0, strerror(errno));
     } else {
         icmp_reflect(so->so_m);
         so->so_m = NULL; /* Don't m_free() it again! */
diff --git a/slirp/ip_icmp.h b/slirp/ip_icmp.h
index be4426b..846761d 100644
--- a/slirp/ip_icmp.h
+++ b/slirp/ip_icmp.h
@@ -156,8 +156,8 @@ struct icmp {
 void icmp_init(Slirp *slirp);
 void icmp_cleanup(Slirp *slirp);
 void icmp_input(struct mbuf *, int);
-void icmp_error(struct mbuf *msrc, u_char type, u_char code, int minsize,
-                const char *message);
+void icmp_send_error(struct mbuf *msrc, u_char type, u_char code, int minsize,
+                     const char *message);
 void icmp_reflect(struct mbuf *);
 void icmp_receive(struct socket *so);
 void icmp_detach(struct socket *so);
diff --git a/slirp/ip_input.c b/slirp/ip_input.c
index e4855ae..16fb2cb 100644
--- a/slirp/ip_input.c
+++ b/slirp/ip_input.c
@@ -132,9 +132,9 @@ ip_input(struct mbuf *m)
 	   m_adj(m, ip->ip_len - m->m_len);
 
 	/* check ip_ttl for a correct ICMP reply */
-	if(ip->ip_ttl==0) {
-	  icmp_error(m, ICMP_TIMXCEED,ICMP_TIMXCEED_INTRANS, 0,"ttl");
-	  goto bad;
+	if (ip->ip_ttl == 0) {
+	    icmp_send_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, 0, "ttl");
+	    goto bad;
 	}
 
 	/*
@@ -637,7 +637,7 @@ typedef uint32_t n_time;
 	}
 	return (0);
 bad:
- 	icmp_error(m, type, code, 0, 0);
+	icmp_send_error(m, type, code, 0, 0);
 
 	return (1);
 }
diff --git a/slirp/socket.c b/slirp/socket.c
index 2b5453e..32b1ba3 100644
--- a/slirp/socket.c
+++ b/slirp/socket.c
@@ -463,7 +463,7 @@ sorecvfrom(struct socket *so)
 
 	    DEBUG_MISC((dfd," udp icmp rx errno = %d-%s\n",
 			errno,strerror(errno)));
-	    icmp_error(so->so_m, ICMP_UNREACH,code, 0,strerror(errno));
+	    icmp_send_error(so->so_m, ICMP_UNREACH, code, 0, strerror(errno));
 	  } else {
 	    icmp_reflect(so->so_m);
             so->so_m = NULL; /* Don't m_free() it again! */
@@ -511,7 +511,7 @@ sorecvfrom(struct socket *so)
 	    else if(errno == ENETUNREACH) code=ICMP_UNREACH_NET;
 
 	    DEBUG_MISC((dfd," rx error, tx icmp ICMP_UNREACH:%i\n", code));
-	    icmp_error(so->so_m, ICMP_UNREACH,code, 0,strerror(errno));
+	    icmp_send_error(so->so_m, ICMP_UNREACH, code, 0, strerror(errno));
 	    m_free(m);
 	  } else {
 	  /*
diff --git a/slirp/tcp_input.c b/slirp/tcp_input.c
index 2027a75..5f845da 100644
--- a/slirp/tcp_input.c
+++ b/slirp/tcp_input.c
@@ -608,7 +608,7 @@ findso:
 	      m->m_data -= sizeof(struct tcpiphdr)+off-sizeof(struct tcphdr);
 	      m->m_len  += sizeof(struct tcpiphdr)+off-sizeof(struct tcphdr);
 	      *ip=save_ip;
-	      icmp_error(m, ICMP_UNREACH,code, 0,strerror(errno));
+	      icmp_send_error(m, ICMP_UNREACH, code, 0, strerror(errno));
 	    }
             tcp_close(tp);
 	    m_free(m);
diff --git a/slirp/udp.c b/slirp/udp.c
index 6b39cab..be012fb 100644
--- a/slirp/udp.c
+++ b/slirp/udp.c
@@ -209,7 +209,8 @@ udp_input(register struct mbuf *m, int iphlen)
 	  m->m_data -= iphlen;
 	  *ip=save_ip;
 	  DEBUG_MISC((dfd,"udp tx errno = %d-%s\n",errno,strerror(errno)));
-	  icmp_error(m, ICMP_UNREACH,ICMP_UNREACH_NET, 0,strerror(errno));
+	  icmp_send_error(m, ICMP_UNREACH, ICMP_UNREACH_NET, 0,
+	                  strerror(errno));
 	  goto bad;
 	}
 
-- 
2.7.0