From 12f08abe221173c43dc22c63e8c62069f96348b4 Mon Sep 17 00:00:00 2001
From: Guus Sliepen <guus@meshlink.io>
Date: Thu, 30 Aug 2018 19:45:13 +0200
Subject: [PATCH] Always add both CanonicalAddress and any local address to the
 invitation URL.

We don't know in advance if the invitee will be on the LAN or outside
the LAN, and because hairpin routing is not working on many home
routers, it is safer to add all possible addresses.

Also, add the port number to each individual address in the URL, instead
of allowing only one port number.
---
 src/meshlink.c | 104 +++++++++++++++++++++++++------------------------
 1 file changed, 53 insertions(+), 51 deletions(-)

diff --git a/src/meshlink.c b/src/meshlink.c
index 69dd7141..a26c4181 100644
--- a/src/meshlink.c
+++ b/src/meshlink.c
@@ -347,63 +347,62 @@ char *meshlink_get_external_address_for_family(meshlink_handle_t *mesh, int fami
 	return hostname;
 }
 
+// String comparison which handles NULL arguments
+static bool safe_streq(const char *a, const char *b) {
+	if (!a || !b)
+		return a == b;
+	else
+		return !strcmp(a, b);
+}
+
 // This gets the hostname part for use in invitation URLs
 static char *get_my_hostname(meshlink_handle_t *mesh) {
-	char *hostname[2] = {NULL};
-	char *port = NULL;
+	char *hostname[3] = {NULL};
+	char *port[3] = {NULL};
 	char *hostport = NULL;
-	char *name = mesh->self->name;
-	char filename[PATH_MAX] = "";
-
-	// Use first Address statement in own host config file
-	snprintf(filename, sizeof(filename), "%s" SLASH "hosts" SLASH "%s", mesh->confbase, name);
-	scan_for_hostname(filename, &hostname[0], &port);
 
-	if(hostname[0]) {
-		goto done;
-	}
-
-	hostname[0] = meshlink_get_external_address_for_family(mesh, AF_INET);
-	hostname[1] = meshlink_get_external_address_for_family(mesh, AF_INET6);
+	// Use the best Address statement in our own host config file
+	char filename[PATH_MAX] = "";
+	snprintf(filename, sizeof(filename), "%s" SLASH "hosts" SLASH "%s", mesh->confbase, mesh->self->name);
+	scan_for_hostname(filename, &hostname[0], &port[0]);
 
-	if(!hostname[0] && !hostname[1]) {
-		return NULL;
-	}
+	hostname[1] = meshlink_get_external_address_for_family(mesh, AF_INET);
+	hostname[2] = meshlink_get_external_address_for_family(mesh, AF_INET6);
 
-	if(hostname[0] && hostname[1] && !strcmp(hostname[0], hostname[1])) {
-		free(hostname[1]);
-		hostname[1] = NULL;
-	}
+	// Concatenate all unique address to the hostport string
+	for (int i = 0; i < 3; i++) {
+		if (!hostname[i])
+			continue;
 
-	port = xstrdup(mesh->myport);
+		// Ignore duplicate hostnames
+		bool found = false;
 
-	for(int i = 0; i < 2; i++) {
-		if(hostname[i]) {
-			char *tmphostport;
-			xasprintf(&tmphostport, "%s %s", hostname[i], port);
-			append_config_file(mesh, mesh->self->name, "Address", tmphostport);
-			free(tmphostport);
+		for (int j = 0; i < j; j++) {
+			if (safe_streq(hostname[i], hostname[j]) && safe_streq(port[i], port[j])) {
+				found = true;
+				break;
+			}
 		}
-	}
 
-done:
-
-	for(int i = 0; i < 2; i++) {
-		if(!hostname[i]) {
+		if (found) {
+			free(hostname[i]);
+			free(port[i]);
+			hostname[i] = NULL;
+			port[i] = NULL;
 			continue;
 		}
 
-		char *newhostport;
-		xasprintf(&newhostport, (strchr(hostname[i], ':') ? "%s%s[%s]" : "%s%s%s"), hostport ? hostport : "", hostport ? "," : "", hostname[i]);
-		free(hostname[i]);
-		free(hostport);
-		hostport = newhostport;
-	}
+		// Ensure we have the same addresses in our own host config file.
+		char *tmphostport;
+		xasprintf(&tmphostport, "%s %s", hostname[i], port[i] ? port[i] : mesh->myport);
+		append_config_file(mesh, mesh->self->name, "Address", tmphostport);
+		free(tmphostport);
 
-	if(port) {
+		// Append the address to the hostport string
 		char *newhostport;
-		xasprintf(&newhostport, "%s:%s", hostport, port);
-		free(port);
+		xasprintf(&newhostport, (strchr(hostname[i], ':') ? "%s%s[%s]:%s" : "%s%s%s:%s"), hostport ? hostport : "", hostport ? "," : "", hostname[i], port[i] ? port[i] : mesh->myport);
+		free(hostname[i]);
+		free(port[i]);
 		free(hostport);
 		hostport = newhostport;
 	}
@@ -2034,7 +2033,7 @@ bool meshlink_join(meshlink_handle_t *mesh, const char *invitation) {
 	char copy[strlen(invitation) + 1];
 	strcpy(copy, invitation);
 
-	// Split the invitation URL into hostname, port, key hash and cookie.
+	// Split the invitation URL into a list of hostname/port tuples, a key hash and a cookie.
 
 	char *slash = strchr(copy, '/');
 
@@ -2049,13 +2048,7 @@ bool meshlink_join(meshlink_handle_t *mesh, const char *invitation) {
 	}
 
 	char *address = copy;
-	char *port = strrchr(address, ':');
-
-	if(!port) {
-		goto invalid;
-	}
-
-	*port++ = 0;
+	char *port = NULL;
 
 	if(!b64decode(slash, mesh->hash, 18) || !b64decode(slash + 24, mesh->cookie, 18)) {
 		goto invalid;
@@ -2082,6 +2075,15 @@ bool meshlink_join(meshlink_handle_t *mesh, const char *invitation) {
 			*comma++ = 0;
 		}
 
+		// Split of the port
+		port = strrchr(address, ':');
+
+		if(!port) {
+			goto invalid;
+		}
+
+		*port++ = 0;
+
 		// IPv6 address are enclosed in brackets, per RFC 3986
 		if(*address == '[') {
 			address++;
@@ -2093,7 +2095,7 @@ bool meshlink_join(meshlink_handle_t *mesh, const char *invitation) {
 
 			*bracket++ = 0;
 
-			if(comma && bracket != comma) {
+			if(*bracket) {
 				goto invalid;
 			}
 		}
-- 
2.39.5