icmp, icmp6: Add icmp_forward_error and icmp6_forward_error

They work like icmp_send_error and icmp6_send_error but allow to specify
the source IP address

Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>

4 files changed, 20 insertions, 5 deletions

diff --git a/src/ip6_icmp.c b/src/ip6_icmp.c
index d9c872b..119c8be 100644
--- a/src/ip6_icmp.c
+++ b/src/ip6_icmp.c
@@ -69,7 +69,7 @@ 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)
+void icmp6_forward_error(struct mbuf *m, uint8_t type, uint8_t code, struct in6_addr *src)
 {
     Slirp *slirp = m->slirp;
     struct mbuf *t;
@@ -88,7 +88,7 @@ void icmp6_send_error(struct mbuf *m, uint8_t type, uint8_t code)
 
     /* IPv6 packet */
     struct ip6 *rip = mtod(t, struct ip6 *);
-    rip->ip_src = (struct in6_addr)LINKLOCAL_ADDR;
+    rip->ip_src = *src;
     rip->ip_dst = ip->ip_src;
     inet_ntop(AF_INET6, &rip->ip_dst, addrstr, INET6_ADDRSTRLEN);
     DEBUG_ARG("target = %s", addrstr);
@@ -131,6 +131,12 @@ void icmp6_send_error(struct mbuf *m, uint8_t type, uint8_t code)
     ip6_output(NULL, t, 0);
 }
 
+void icmp6_send_error(struct mbuf *m, uint8_t type, uint8_t code)
+{
+    struct in6_addr src = LINKLOCAL_ADDR;
+    icmp6_forward_error(m, type, code, &src);
+}
+
 /*
  * Send NDP Router Advertisement
  */
diff --git a/src/ip6_icmp.h b/src/ip6_icmp.h
index c37e60f..9070999 100644
--- a/src/ip6_icmp.h
+++ b/src/ip6_icmp.h
@@ -212,6 +212,7 @@ struct ndpopt {
 void icmp6_init(Slirp *slirp);
 void icmp6_cleanup(Slirp *slirp);
 void icmp6_input(struct mbuf *);
+void icmp6_forward_error(struct mbuf *m, uint8_t type, uint8_t code, struct in6_addr *src);
 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/src/ip_icmp.c b/src/ip_icmp.c
index 13a0e55..94afba6 100644
--- a/src/ip_icmp.c
+++ b/src/ip_icmp.c
@@ -256,8 +256,8 @@ end_error:
  */
 
 #define ICMP_MAXDATALEN (IP_MSS - 28)
-void icmp_send_error(struct mbuf *msrc, uint8_t type, uint8_t code, int minsize,
-                     const char *message)
+void icmp_forward_error(struct mbuf *msrc, uint8_t type, uint8_t code, int minsize,
+                        const char *message, struct in_addr *src)
 {
     unsigned hlen, shlen, s_ip_len;
     register struct ip *ip;
@@ -372,7 +372,7 @@ void icmp_send_error(struct mbuf *msrc, uint8_t type, uint8_t code, int minsize,
     ip->ip_ttl = MAXTTL;
     ip->ip_p = IPPROTO_ICMP;
     ip->ip_dst = ip->ip_src; /* ip addresses */
-    ip->ip_src = m->slirp->vhost_addr;
+    ip->ip_src = *src;
 
     (void)ip_output((struct socket *)NULL, m);
 
@@ -381,6 +381,12 @@ end_error:
 }
 #undef ICMP_MAXDATALEN
 
+void icmp_send_error(struct mbuf *msrc, uint8_t type, uint8_t code, int minsize,
+                     const char *message)
+{
+    icmp_forward_error(msrc, type, code, minsize, message, &msrc->slirp->vhost_addr);
+}
+
 /*
  * Reflect the ip packet back to the source
  */
diff --git a/src/ip_icmp.h b/src/ip_icmp.h
index 84707db..569a083 100644
--- a/src/ip_icmp.h
+++ b/src/ip_icmp.h
@@ -157,6 +157,8 @@ struct icmp {
 void icmp_init(Slirp *slirp);
 void icmp_cleanup(Slirp *slirp);
 void icmp_input(struct mbuf *, int);
+void icmp_forward_error(struct mbuf *msrc, uint8_t type, uint8_t code, int minsize,
+                        const char *message, struct in_addr *src);
 void icmp_send_error(struct mbuf *msrc, uint8_t type, uint8_t code, int minsize,
                      const char *message);
 void icmp_reflect(struct mbuf *);