avahi: Fix detection of contexts at IPv6 addresses

The IPv6 addresses at which a IIO context has been detected were translated to Libiio URIs, so that the final part can create a Libiio context to verify that the contexts actually exist. However, those URIs were built without the interface specifier, which caused the contexts at IPv6 link-local addresses to being skipped as the Libiio context wouldn't create properly. Signed-off-by: Paul Cercueil <[email protected]>
analogdevicesinc · Jul 10, 2023 · 8904ef7 · 8904ef7
1 parent eebff52
commit 8904ef7
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Showing 2 changed files with 20 additions and 3 deletions.
diff --git a/dns_sd.h b/dns_sd.h
@@ -15,11 +15,15 @@
 
 #ifdef _WIN32
 #include <winsock2.h>
+#include <ntddndis.h>
+#include <netioapi.h>
 #else
+#include <net/if.h>
 #include <sys/param.h>
 #endif
 
-#define DNS_SD_ADDRESS_STR_MAX (40) /* IPv6 Max = 4*8 + 7 + 1 for NUL */
+/* IPv6 Max = 4*8 + 7 + 1 for '%' + interface length */
+#define DNS_SD_ADDRESS_STR_MAX (40 + IF_NAMESIZE)
 #define FQDN_LEN (255)              /* RFC 1035 */
 
 /* MacOS doesn't include ENOMEDIUM (No medium found) like Linux does */

diff --git a/dns_sd_avahi.c b/dns_sd_avahi.c
@@ -51,10 +51,13 @@ static struct dns_sd_discovery_data *new_discovery_data(void)
 }
 
 static void avahi_process_resolved(struct dns_sd_discovery_data *ddata,
+				   AvahiIfIndex iface,
 				   const AvahiAddress *addr,
 				   const char *host_name,
 				   const uint16_t port)
 {
+	char *ptr;
+
 	/* Avahi is multi-threaded, so lock the list */
 	iio_mutex_lock(ddata->lock);
 	ddata->resolved++;
@@ -83,6 +86,16 @@ static void avahi_process_resolved(struct dns_sd_discovery_data *ddata,
 	}
 	iio_mutex_unlock(ddata->lock);
 
+	ptr = ddata->addr_str + strnlen(ddata->addr_str, DNS_SD_ADDRESS_STR_MAX);
+
+	if (addr->proto == AVAHI_PROTO_INET6
+	    && addr->data.ipv6.address[0] == 0xfe
+	    && addr->data.ipv6.address[1] == 0x80
+	    && iface != AVAHI_IF_UNSPEC
+	    && if_indextoname((unsigned int)iface, ptr + 1)) {
+		*ptr = '%';
+	}
+
 	IIO_DEBUG("\t\t%s:%u (%s)\n", host_name, port, ddata->addr_str);
 }
 
@@ -126,7 +139,7 @@ static void __avahi_resolver_cb(AvahiServiceResolver *resolver,
 			  avahi_strerror(err));
 		break;
 	case AVAHI_RESOLVER_FOUND: {
-		avahi_process_resolved(ddata, address, host_name, port);
+		avahi_process_resolved(ddata, iface, address, host_name, port);
 		IIO_DEBUG("Avahi Resolver : service '%s' of type '%s' in domain '%s':\n",
 			  name, type, domain);
 		break;
@@ -157,7 +170,7 @@ static void avahi_host_resolver(AvahiHostNameResolver *resolver,
 			  host_name, avahi_strerror(err));
 		break;
 	case AVAHI_RESOLVER_FOUND:
-		avahi_process_resolved(ddata, address, host_name, IIOD_PORT);
+		avahi_process_resolved(ddata, iface, address, host_name, IIOD_PORT);
 		break;
 	}