fixes #509 We need "relative" IPC URLs

This special cases the URL parser for inproc and IPC urls,
changing so that they no longer parse the thing after the ://
as anything special.  This allows IPC URLs to be relative.

3 files changed, 34 insertions, 19 deletions

diff --git a/docs/man/nng_ipc.7.adoc b/docs/man/nng_ipc.7.adoc
index 9b49c87c..0ebf1d3d 100644
--- a/docs/man/nng_ipc.7.adoc
+++ b/docs/man/nng_ipc.7.adoc
@@ -41,14 +41,21 @@ no extra steps to use it should be necessary.
 === URI Format
 
 (((URI, `ipc://`)))
-This transport uses URIs using the scheme `ipc://`, followed by
-an absolute path name in the file system where the socket or named pipe
-should be created.
+This transport uses URIs using the scheme `ipc://`, followed by a path
+name in the file system where the socket or named pipe should be created.
 
 TIP: On Windows, all names are prefixed by `\\.\pipe\` and do not
-occupy the normal file system.
-On POSIX platforms, the path is taken literally,
-and is relative to the root directory.
+reside in the normal file system.
+On POSIX platforms, the path is taken literally, and is relative to
+the current directory, unless it begins with `/`, in which case it is
+relative to the root directory.
+
+NOTE: When using relative paths on POSIX systems, the address used and returned
+in properties like `NNG_OPT_LOCADDR` and `NNG_OPT_URL` will also be relative.
+Consequently, they will only be interpreted the same by processes that have
+the same working directory.
+To ensure maximum portability and safety, absolute paths are recommended
+whenever possible.
 
 NOTE: If compatibility with legacy _nanomsg_ applications is required,
 then pathnames must not be longer than 122 bytes, including the final
@@ -56,9 +63,6 @@ then pathnames must not be longer than 122 bytes, including the final
 This is because legacy versions of _nanomsg_ cannot express URLs
 longer than 128 bytes, including the `ipc://` prefix.
 
-NOTE: Legacy _nanomsg_ supported relative IPC path names; modern _nng_ does not.
-Therefore, always use an absolute path name if interoperability is required.
-
 === Socket Address
 
 When using an `<<nng_sockaddr.5#,nng_sockaddr>>` structure,
diff --git a/src/core/url.c b/src/core/url.c
index 7d45f82d..dfbd2a88 100644
--- a/src/core/url.c
+++ b/src/core/url.c
@@ -288,11 +288,30 @@ nni_url_parse(nni_url **urlp, const char *raw)
 		url->u_scheme[i] = (char) tolower(s[i]);
 	}
 	url->u_scheme[len] = '\0';
+	s += len + 3; // strlen("://")
+
+	// For compatibility reasons, we treat ipc:// and inproc:// paths
+	// specially. These names URLs have a path name (ipc) or arbitrary
+	// string (inproc) and don't include anything like a host.  Note that
+	// in the case of path names, it is incumbent upon the application to
+	// ensure that valid and safe path names are used.  Note also that
+	// path names are not canonicalized, which means that the address and
+	// URL properties for relative paths won't be portable to other
+	// processes unless they are in the same directory.  When in doubt,
+	// we recommend using absolute paths, such as ipc:///var/run/mysocket.
+
+	if ((strcmp(url->u_scheme, "ipc") == 0) ||
+	    (strcmp(url->u_scheme, "inproc") == 0)) {
+		if ((url->u_path = nni_strdup(s)) == NULL) {
+			rv = NNG_ENOMEM;
+			goto error;
+		}
+		*urlp = url;
+	}
 
 	// Look for host part (including colon).  Will be terminated by
 	// a path, or NUL.  May also include an "@", separating a user
 	// field.
-	s += len + 3; // strlen("://")
 	for (len = 0; (c = s[len]) != '/'; len++) {
 		if ((c == '\0') || (c == '#') || (c == '?')) {
 			break;
@@ -317,11 +336,7 @@ nni_url_parse(nni_url **urlp, const char *raw)
 	// If the hostname part is just '*', skip over it.  (We treat it
 	// as an empty host for legacy nanomsg compatibility.  This may be
 	// non-RFC compliant, but we're really only interested in parsing
-	// nanomsg URLs.  One weird side effect of this is that some URLS
-	// which would be invalid (ipc://*/bogus for example) will now parse
-	// to something that might be surprising (ipc:///bogus now), for
-	// example -- although in the IPC case the URL is *always* a local
-	// path without any host component.
+	// nanomsg URLs.)
 	if (((len == 1) && (s[0] == '*')) ||
 	    ((len > 1) && (strncmp(s, "*:", 2) == 0))) {
 		s++;
diff --git a/src/transport/ipc/ipc.c b/src/transport/ipc/ipc.c
index 88e11fb1..6191dea6 100644
--- a/src/transport/ipc/ipc.c
+++ b/src/transport/ipc/ipc.c
@@ -628,10 +628,6 @@ nni_ipc_ep_init(void **epp, nni_url *url, nni_sock *sock, int mode)
 	int         rv;
 	size_t      sz;
 
-	if (((url->u_host != NULL) && (strlen(url->u_host) > 0)) ||
-	    (url->u_userinfo != NULL)) {
-		return (NNG_EINVAL);
-	}
 	if ((ep = NNI_ALLOC_STRUCT(ep)) == NULL) {
 		return (NNG_ENOMEM);
 	}