passt: Add support for multiple instances in different network namespaces

...sharing the same filesystem. Instead of a fixed path for the UNIX
domain socket, passt now uses a path with a counter, probing for
existing instances, and picking the first free one.

The demo script is updated accordingly -- it can now be started several
times to create multiple namespaces with an instance of passt each,
with addressing reflecting separate subnets, and NDP proxying between
them.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

1 files changed, 12 insertions, 2 deletions

diff --git a/pcap.c b/pcap.c
index 2767b53..8dd647a 100644
--- a/pcap.c
+++ b/pcap.c
@@ -20,6 +20,10 @@
 #include <time.h>
 #include <net/ethernet.h>
 #include <unistd.h>
+#include <net/if.h>
+
+#include "passt.h"
+#include "util.h"
 
 #ifdef DEBUG
 
@@ -77,9 +81,9 @@ void pcap(char *pkt, size_t len)
 	write(pcap_fd, pkt, len);
 }
 
-void pcap_init(void)
+void pcap_init(int sock_index)
 {
-	char name[] = PCAP_PREFIX PCAP_ISO8601_STR ".pcap";
+	char name[] = PCAP_PREFIX PCAP_ISO8601_STR STR(UNIX_SOCK_MAX) ".pcap";
 	struct timeval tv;
 	struct tm *tm;
 
@@ -88,6 +92,10 @@ void pcap_init(void)
 	strftime(name + strlen(PCAP_PREFIX), sizeof(PCAP_ISO8601_STR) - 1,
 		 PCAP_ISO8601_FORMAT, tm);
 
+	snprintf(name + strlen(PCAP_PREFIX) + strlen(PCAP_ISO8601_STR),
+		 sizeof(name) - strlen(PCAP_PREFIX) - strlen(PCAP_ISO8601_STR),
+		 "_%i.pcap", sock_index);
+
 	pcap_fd = open(name, O_WRONLY | O_CREAT | O_APPEND | O_DSYNC,
 		       S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
 	if (pcap_fd == -1) {
@@ -95,6 +103,8 @@ void pcap_init(void)
 		return;
 	}
 
+	info("Saving packet capture at %s", name);
+
 	write(pcap_fd, &pcap_hdr, sizeof(pcap_hdr));
 }