[PATCH 10/18] comm, udp: Provide an addr_to_string method

[Ian Jackson]

This method writes (into a single static buffer) a string describing a
comm_addr.  It describes both the comm instance and the peer address.

No callers yet, but one is about to be introduced.

Signed-off-by: Ian Jackson <ijackson at chiark.greenend.org.uk>
---
 secnet.h |    4 ++++
 udp.c    |   27 +++++++++++++++++++++++++++
 2 files changed, 31 insertions(+), 0 deletions(-)

diff --git a/secnet.h b/secnet.h
index 809b3a7..fbb7660 100644
--- a/secnet.h
+++ b/secnet.h
@@ -325,6 +325,9 @@ typedef void comm_release_notify_fn(void *commst, void *nst,
 				    comm_notify_fn *fn);
 typedef bool_t comm_sendmsg_fn(void *commst, struct buffer_if *buf,
 			       const struct comm_addr *dest);
+typedef const char *comm_addr_to_string_fn(void *commst,
+					   const struct comm_addr *ca);
+        /* Returned string is in a static buffer. */
 struct comm_if {
     void *st;
     int32_t min_start_pad;
@@ -332,6 +335,7 @@ struct comm_if {
     comm_request_notify_fn *request_notify;
     comm_release_notify_fn *release_notify;
     comm_sendmsg_fn *sendmsg;
+    comm_addr_to_string_fn *addr_to_string;
 };
 
 /* LOG interface */
diff --git a/udp.c b/udp.c
index 8ec8581..f420664 100644
--- a/udp.c
+++ b/udp.c
@@ -16,6 +16,8 @@
 #include <errno.h>
 #include <sys/socket.h>
 #include <sys/wait.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
 #include "util.h"
 #include "unaligned.h"
 #include "ipaddr.h"
@@ -46,6 +48,30 @@ struct udp {
     struct sockaddr_in proxy;
 };
 
+static const char *saddr_to_string(const struct sockaddr_in *sin) {
+    static char bufs[2][100];
+    static int b;
+
+    b ^= 1;
+    snprintf(bufs[b], sizeof(bufs[b]), "[%s]:%d",
+	     inet_ntoa(sin->sin_addr),
+	     ntohs(sin->sin_port));
+    return bufs[b];
+}
+
+static const char *addr_to_string(void *commst, const struct comm_addr *ca) {
+    struct udp *st=commst;
+    static char sbuf[100];
+
+    struct sockaddr_in la;
+    la.sin_addr.s_addr=htonl(st->addr);
+    la.sin_port=htons(st->port);
+
+    snprintf(sbuf, sizeof(sbuf), "udp:%s-%s",
+	     saddr_to_string(&la), saddr_to_string(&ca->sin));
+    return sbuf;
+}
+
 static int udp_beforepoll(void *state, struct pollfd *fds, int *nfds_io,
 			  int *timeout_io)
 {
@@ -267,6 +293,7 @@ static list_t *udp_apply(closure_t *self, struct cloc loc, dict_t *context,
     st->ops.request_notify=request_notify;
     st->ops.release_notify=release_notify;
     st->ops.sendmsg=udp_sendmsg;
+    st->ops.addr_to_string=addr_to_string;
     st->port=0;
     st->use_proxy=False;
 
-- 
1.7.2.5