Initial implementation of a routing table

doc/gmnisrvini.scd

@@ -42,15 +42,46 @@ The following keys are accepted under the *[:tls]* section:
 	the name of the organization responsible for the host and it will be
 	filled in as the X.509 /O name.
 
-## HOST KEYS
+## ROUTING KEYS
 
-Hosts that *gmnisrv* is to serve shall be defined in *gmnisrv.ini* by
-introducing config sections named after each host to provide service for. The
-following keys apply:
+To configure *gmnisrv* to service requests, routing keys must be defined. The
+name of the configuration section is used to determine what kinds of requests it
+configures.
+
+The format of the section name is the _hostname_ to be serviced, followed by a
+token which defines the routing strategy, and a string whose format is specific
+to each routing strategy. The token and match string may be omitted
+(i.e. [_hostname_] alone), which implies path routing against "/".
+
+|] *:*
+:< Route by path prefix. The URL path is compared to "_string_/".
+|  *=*
+:  Exact match. The URL path must exactly match the string.
+|  *~*
+:  Regular expression routing. The string is a JavaScript-compatible regular
+   expression which is tested against the URL path.
+
+Some example section names and examples of matching paths:
+
+|[ *[example.org:/foo]*
+:< /foo, /foo/bar, /foo/bar/baz
+|  *[example.org=/foo.txt]*
+:  /foo.txt
+|  *[example.org~/[a-z]+\\.(png|jpg|webp)*
+:  /foo.png, /bar.webp
+
+Routes should be ordered from least to most specific. The matching algorithm
+attempts to match the URL against each route in reverse order, and chooses the
+first route which matches.
+
+Within each routing section, the following keys are used to configure how
+*gmnisrv* will respond to matching requests:
 
 *root*
 	Configures the path on disk from which files shall be served for this
-	host.
+	host. If using path prefix matching, the prefix is trimmed, so if
+	example.org/foo/bar.txt is requested and matches *[example.org:/foo]*,
+	"bar.txt" will be appended to the root to form the file path.
 
 *index*
 	Configures the name of the index file which shall be served in the event

include/config.h

@@ -2,6 +2,7 @@
 #define GMNISRV_CONFIG
 #include <arpa/inet.h>
 #include <openssl/x509.h>
+#include <regex.h>
 #include <stdbool.h>
 
 struct gmnisrv_tls {
@@ -10,15 +11,33 @@ struct gmnisrv_tls {
 	SSL_CTX *ssl_ctx;
 };
 
-struct gmnisrv_host {
-	char *hostname;
+enum gmnisrv_routing {
+	ROUTE_PATH,
+	ROUTE_REGEX,
+};
+
+struct gmnisrv_route {
+	enum gmnisrv_routing routing;
+	char *spec;
+	union {
+		char *path;
+		regex_t *regex;
+	};
+
 	char *root;
 	char *index;
 	bool autoindex;
 
+	struct gmnisrv_route *next;
+};
+
+struct gmnisrv_host {
+	char *hostname;
 	X509 *x509;
 	EVP_PKEY *pkey;
 
+	struct gmnisrv_route *routes;
+
 	struct gmnisrv_host *next;
 };
 

src/config.c

@@ -21,6 +21,21 @@ gmnisrv_config_get_host(struct gmnisrv_config *conf, const char *hostname)
 	return NULL;
 }
 
+struct gmnisrv_route *
+gmnisrv_host_get_route(struct gmnisrv_host *host,
+		enum gmnisrv_routing routing, const char *spec)
+{
+	struct gmnisrv_route *route = host->routes;
+	while (route) {
+		if (route->routing == routing
+				&& strcmp(route->spec, spec) == 0) {
+			return route;
+		}
+		route = route->next;
+	}
+	return NULL;
+}
+
 static int
 parse_listen(struct gmnisrv_config *conf, const char *value)
 {
@@ -133,7 +148,29 @@ conf_ini_handler(void *user, const char *section,
 		return 0;
 	}
 
-	struct gmnisrv_host *host = gmnisrv_config_get_host(conf, section);
+	const char *spec;
+	char hostname[1024 + 1];
+	enum gmnisrv_routing routing;
+	size_t hostln = strcspn(section, ":~");
+	switch (section[hostln]) {
+	case '\0':
+		routing = ROUTE_PATH;
+		spec = "/";
+		break;
+	case ':':
+		routing = ROUTE_PATH;
+		spec = &section[hostln + 1];
+		break;
+	case '~':
+		routing = ROUTE_REGEX;
+		spec = &section[hostln + 1];
+		break;
+	}
+	assert(hostln < sizeof(hostname));
+	strncpy(hostname, section, hostln);
+	hostname[hostln] = '\0';
+
+	struct gmnisrv_host *host = gmnisrv_config_get_host(conf, hostname);
 	if (!host) {
 		host = calloc(1, sizeof(struct gmnisrv_host));
 		assert(host);
@@ -142,33 +179,52 @@ conf_ini_handler(void *user, const char *section,
 		conf->hosts = host;
 	}
 
+	struct gmnisrv_route *route =
+		gmnisrv_host_get_route(host, routing, spec);
+	if (!route) {
+		route = calloc(1, sizeof(struct gmnisrv_route));
+		assert(route);
+		route->spec = strdup(spec);
+		route->routing = routing;
+		route->next = host->routes;
+		host->routes = route;
+
+		switch (route->routing) {
+		case ROUTE_PATH:
+			route->path = strdup(spec);
+			break;
+		case ROUTE_REGEX:
+			assert(0); // TODO
+		}
+	}
+
 	struct {
 		char *name;
 		char **value;
-	} host_strvars[] = {
-		{ "root", &host->root },
-		{ "index", &host->index },
+	} route_strvars[] = {
+		{ "root", &route->root },
+		{ "index", &route->index },
 	};
 	struct {
 		char *name;
 		bool *value;
-	} host_bvars[] = {
-		{ "autoindex", &host->autoindex },
+	} route_bvars[] = {
+		{ "autoindex", &route->autoindex },
 	};
 
-	for (size_t i = 0; i < sizeof(host_strvars) / sizeof(host_strvars[0]); ++i) {
-		if (strcmp(host_strvars[i].name, name) != 0) {
+	for (size_t i = 0; i < sizeof(route_strvars) / sizeof(route_strvars[0]); ++i) {
+		if (strcmp(route_strvars[i].name, name) != 0) {
 			continue;
 		}
-		*host_strvars[i].value = strdup(value);
+		*route_strvars[i].value = strdup(value);
 		return 1;
 	}
 
-	for (size_t i = 0; i < sizeof(host_bvars) / sizeof(host_bvars[0]); ++i) {
-		if (strcmp(host_bvars[i].name, name) != 0) {
+	for (size_t i = 0; i < sizeof(route_bvars) / sizeof(route_bvars[0]); ++i) {
+		if (strcmp(route_bvars[i].name, name) != 0) {
 			continue;
 		}
-		*host_bvars[i].value =
+		*route_bvars[i].value =
 			strcasecmp(value, "yes") == 0 ||
 			strcasecmp(value, "true") == 0 ||
 			strcasecmp(value, "on") == 0;
@@ -233,8 +289,15 @@ config_finish(struct gmnisrv_config *conf)
 	while (host) {
 		struct gmnisrv_host *next = host->next;
 		free(host->hostname);
-		free(host->root);
-		free(host->index);
+
+		struct gmnisrv_route *route = host->routes;
+		while (route) {
+			struct gmnisrv_route *rnext = route->next;
+			free(route->root);
+			free(route->index);
+			free(route);
+			route = rnext;
+		}
 		free(host);
 		host = next;
 	}

src/serve.c

@@ -117,15 +117,60 @@ internal_error:
 	goto exit;
 }
 
+static bool
+route_match(struct gmnisrv_route *route, const char *path, const char **revised)
+{
+	switch (route->routing) {
+	case ROUTE_PATH:;
+		size_t l = strlen(route->path);
+		if (strncmp(path, route->path, l) != 0) {
+			return false;
+		}
+		if (route->path[l-1] != '/' && path[l] != '\0' && path[l] != '/') {
+			// Prevents path == "/foobar" from matching
+			// route == "/foo":
+			return false;
+		}
+		if (route->path[l-1] == '/') {
+			*revised = &path[l-1];
+		} else {
+			*revised = &path[l];
+		}
+		return true;
+	case ROUTE_REGEX:
+		assert(0); // TODO
+	}
+
+	assert(0); // Invariant
+}
+
 void
 serve_request(struct gmnisrv_client *client)
 {
 	struct gmnisrv_host *host = client->host;
 	assert(host);
-	assert(host->root); // TODO: reverse proxy support
+	struct gmnisrv_route *route = host->routes;
+	assert(route);
+
+	const char *url_path;
+	while (route) {
+		if (route_match(route, client->path, &url_path)) {
+			break;
+		}
+
+		route = route->next;
+	}
+
+	if (!route) {
+		client_submit_response(client,
+			GEMINI_STATUS_NOT_FOUND, "Not found", NULL);
+		return;
+	}
+
+	assert(route->root); // TODO: reverse proxy support
 
 	char path[PATH_MAX + 1];
-	int n = snprintf(path, sizeof(path), "%s%s", host->root, client->path);
+	int n = snprintf(path, sizeof(path), "%s%s", route->root, url_path);
 	if ((size_t)n >= sizeof(path)) {
 		client_submit_response(client, GEMINI_STATUS_PERMANENT_FAILURE,
 			"Request path exceeds PATH_MAX", NULL);
@@ -142,12 +187,12 @@ serve_request(struct gmnisrv_client *client)
 		}
 
 		if (S_ISDIR(st.st_mode)) {
-			if (host->autoindex) {
+			if (route->autoindex) {
 				serve_autoindex(client, path);
 				return;
 			} else {
 				strncat(path,
-					host->index ? host->index : "index.gmi",
+					route->index ? route->index : "index.gmi",
 					sizeof(path) - 1);
 			}
 		} else if (S_ISLNK(st.st_mode)) {