Implement file backend

3 files changed, 223 insertions, 0 deletions

diff --git a/plugins/backend_file.c b/plugins/backend_file.c
new file mode 100644
index 0000000..c3ed8ea
--- /dev/null
+++ b/plugins/backend_file.c
@@ -0,0 +1,204 @@
+#include "backend_file.h"
+#include <string.h>
+#include <stdio.h>
+
+//FIXME allocated this statically because i dont want to do it properly right now tbh
+#define BACKEND_FILE_MAX_PATH 8192
+
+static char* backend_path = NULL;
+
+size_t expressions = 0;
+static char** expression = NULL;
+
+uint64_t init(){
+	//initialize the backend path to empty to be able to use it without problems later
+	backend_path = strdup("");
+
+	if(!backend_path){
+		fprintf(stderr, "Failed to allocate memory\n");
+		return 0;
+	}
+	return WEBSOCKSY_API_VERSION;
+}
+
+uint64_t configure(char* key, char* value){
+	if(!strcmp(key, "path")){
+		free(backend_path);
+		backend_path = strdup(value);
+		if(!backend_path){
+			fprintf(stderr, "Failed to allocate memory\n");
+			return 1;
+		}
+
+		if(strlen(backend_path) && backend_path[strlen(backend_path) - 1] == '/'){
+			backend_path[strlen(backend_path) - 1] = 0;
+		}
+		return 0;
+	}
+	else if(!strcmp(key, "expression")){
+		expression = realloc(expression, (expressions + 1) * sizeof(char*));
+		if(!expression){
+			fprintf(stderr, "Failed to allocate memory\n");
+			return 1;
+		}
+		expression[expressions] = strdup(value);
+		if(!expression[expressions]){
+			fprintf(stderr, "Failed to allocate memory\n");
+			return 1;
+		}
+		expressions++;
+		return 0;
+	}
+
+	fprintf(stderr, "Unknown backend configuration option %s\n", key);
+	return 1;
+}
+
+static int expression_replace(char* buffer, size_t buffer_length, size_t variable_length, char* content, size_t content_length){
+	//check whether the replacement fits
+	if(variable_length < content_length && strlen(buffer) + (content_length - variable_length) >= buffer_length){
+		fprintf(stderr, "Expression replacement buffer overrun\n");
+		return 1;
+	}
+
+	//move data after the replacement
+	memmove(buffer + content_length, buffer + variable_length, strlen(buffer) - variable_length + 1);
+
+	//insert replacement
+	memcpy(buffer, content, content_length);
+	
+	return 0;
+}
+
+static int expression_resolve(char* template, size_t length, char* endpoint, size_t headers, ws_http_header* header){
+	size_t u, index_len, p, value_len, variable_len;
+	char* index, *value;
+
+	for(u = 0; template[u]; u++){
+		index_len = 0;
+		variable_len = 0;
+		value = NULL;
+		if(template[u] == '%'){
+			if(!strncmp(template + u, "%endpoint%", 10)){
+				if(strlen(endpoint) < 1){
+					return 1;
+				}
+
+				//TODO rtrim slash
+				//replace with sanitized endpoint string
+				for(p = 0; endpoint[p]; p++){
+					if(endpoint[p] == '/'){
+						endpoint[p] = '_';
+					}
+				}
+
+				value = endpoint + 1;
+				value_len = p - 1;
+				variable_len = 10;
+			}
+			else if(!strncmp(template + u, "%cookie:", 8)){
+				//scan cookie values
+				index = template + u + 8;
+				for(; index[index_len] && index[index_len] != '%'; index_len++){
+				}
+				if(!index[index_len]){
+					fprintf(stderr, "Unterminated expression variable: %s\n", index);
+					return 1;
+				}
+
+				//TODO iterate cookies
+			}
+			else if(!strncmp(template + u, "%header:", 8)){
+				//scan headers
+				index = template + u + 8;
+				for(; index[index_len] && index[index_len] != '%'; index_len++){
+				}
+				if(!index[index_len]){
+					fprintf(stderr, "Unterminated expression variable: %s\n", index);
+					return 1;
+				}
+				//find the correct header
+				for(p = 0; p < headers; p++){
+					if(strlen(header[p].tag) == index_len
+							&& !strncmp(header[p].tag, index, index_len)){
+						break;
+					}
+				}
+
+				//no such header -> fail the expression
+				if(p == headers){
+					return 1;
+				}
+
+				value = header[p].value;
+				value_len = strlen(value);
+				variable_len = 8 + index_len + 1;
+			}
+
+			//perform replacement
+			if(value && expression_replace(template + u, length - u, variable_len, value, value_len)){
+				fprintf(stderr, "Expression replacement failed\n");
+				return 1;
+			}
+
+			//skip the inserted value
+			u += value_len - 1;
+		}
+	}
+
+	return 0;
+}
+
+ws_peer_info query(char* endpoint, size_t protocols, char** protocol, size_t headers, ws_http_header* header, websocket* ws){
+	size_t u, line_alloc = 0;
+	ssize_t line_length = 0;
+	char* line = NULL;
+	FILE* input = NULL;
+	char target_path[BACKEND_FILE_MAX_PATH];
+	ws_peer_info peer = {
+		.transport = peer_transport_detect,
+	};
+
+	for(u = 0; u < expressions; u++){
+		//evaluate the current expression to find a path
+		snprintf(target_path, sizeof(target_path), "%s/%s", backend_path, expression[u]);
+		if(expression_resolve(target_path + strlen(backend_path) + 1, sizeof(target_path) - strlen(backend_path) - 1, endpoint, headers, header)){
+			continue;
+		}
+	
+		//check whether the file exists
+		input = fopen(target_path, "r");
+		if(!input){
+			continue;
+		}
+
+		//read it
+		for(line_length = getline(&line, &line_alloc, input); line_length >= 0; line_length = getline(&line, &line_alloc, input)){
+			//TODO evaluate line in file
+			fprintf(stderr, "File %s, line %s\n", target_path, line);
+		}
+		fclose(input);
+
+		//if peer found, break
+		if(peer.host){
+			break;
+		}
+	}
+
+	free(line);
+	return peer;
+}
+
+void cleanup(){
+	size_t u;
+
+	for(u = 0; u < expressions; u++){
+		free(expression[u]);
+	}
+	free(expression);
+	expression = NULL;
+	expressions = 0;
+
+	free(backend_path);
+	backend_path = NULL;
+}
diff --git a/plugins/backend_file.h b/plugins/backend_file.h
new file mode 100644
index 0000000..04b3528
--- /dev/null
+++ b/plugins/backend_file.h
@@ -0,0 +1,6 @@
+#include "../websocksy.h"
+
+uint64_t init();
+uint64_t configure(char* key, char* value);
+ws_peer_info query(char* endpoint, size_t protocols, char** protocol, size_t headers, ws_http_header* header, websocket* ws);
+void cleanup();
diff --git a/plugins/makefile b/plugins/makefile
new file mode 100644
index 0000000..6b413db
--- /dev/null
+++ b/plugins/makefile
@@ -0,0 +1,13 @@
+.PHONY: all clean
+PLUGINS = backend_file.so
+
+CFLAGS += -fPIC -I../
+LDFLAGS += -shared
+
+%.so :: %.c %.h
+	$(CC) $(CFLAGS) $(LDLIBS) $< -o $@ $(LDFLAGS)
+
+all: $(PLUGINS)
+
+clean:
+	$(RM) $(PLUGINS)