commit d1ca3911d29c9fb2147695b6622d9a088041a534
from: Omar Polo <op@omarpolo.com>
date: Thu Jan 21 22:44:41 2021 UTC

fix redirects

make sure redirect starts with /.  This also requires a tweak in
check_path, in the case we go open_file -> send_dir -> open_file ->
check-path and the path starts with a slash.

commit - 06f233ad8aeb4c82d97e742c38792217e946efe0
commit + d1ca3911d29c9fb2147695b6622d9a088041a534
blob - c1ccbcee9f8abbb5b370ac14fb3a8cbd2ba630e7
blob + 2d80dcb8ace35260868d88c4fef3f5177a92ae67
--- server.c
+++ server.c
@@ -33,10 +33,20 @@ int
 check_path(struct client *c, const char *path, int *fd)
 {
 	struct stat sb;
+	const char *p;
 
 	assert(path != NULL);
-	if ((*fd = openat(c->host->dirfd, *path ? path : ".",
-	    O_RDONLY | O_NOFOLLOW)) == -1) {
+
+	if (*path == '\0')
+		p = ".";
+	else if (*path == '/')
+		/* in send_dir we add an initial / (to be
+		 * redirect-friendly), but here we want to skip it */
+		p = path+1;
+	else
+		p = path;
+
+	if ((*fd = openat(c->host->dirfd, p, O_RDONLY | O_NOFOLLOW)) == -1) {
 		return FILE_MISSING;
 	}
 
@@ -394,11 +404,13 @@ send_dir(struct pollfd *fds, struct client *c)
 		goodbye(fds, c);
 		return;
 	}
+
+	strlcpy(c->sbuf, "/", sizeof(c->sbuf));
 
 	len = strlen(c->iri.path);
 	if (len > 0 && c->iri.path[len-1] != '/') {
 		/* redirect to url with the trailing / */
-		strlcpy(c->sbuf, c->iri.path, sizeof(c->sbuf));
+		strlcat(c->sbuf, c->iri.path, sizeof(c->sbuf));
 		strlcat(c->sbuf, "/", sizeof(c->sbuf));
 		if (!start_reply(fds, c, TEMP_REDIRECT, c->sbuf))
 			return;
@@ -406,9 +418,11 @@ send_dir(struct pollfd *fds, struct client *c)
 		return;
 	}
 
-        strlcpy(c->sbuf, c->iri.path, sizeof(c->sbuf));
-	if (len != 0)
+	strlcat(c->sbuf, c->iri.path, sizeof(c->sbuf));
+
+	if (!ends_with(c->sbuf, "/"))
 		strlcat(c->sbuf, "/", sizeof(c->sbuf));
+
 	len = strlcat(c->sbuf, "index.gmi", sizeof(c->sbuf));
 
 	if (len >= sizeof(c->sbuf)) {