Added http-relay subsystem to add transparent-proxy support to any http proxy.

Makefile

@@ -3,7 +3,7 @@ CFLAGS=-std=gnu99 -Wall -g -O0
 .PHONY: all
 all: redsocks
 
-obj = parser.o main.o redsocks.o log.o http-connect.o socks4.o socks5.o base.o
+obj = parser.o main.o redsocks.o log.o http-connect.o socks4.o socks5.o http-relay.o base.o
 src = $(patsubst %.o,%.c,$(obj))
 
 redsocks: $(obj)

http-relay.c

@@ -0,0 +1,246 @@
+/** http-relay upstream module for redsocks
+ * $Id$ 
+ */
+
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "log.h"
+#include "redsocks.h"
+
+typedef enum httpr_state_t {
+	httpr_new,
+} httpr_state;
+
+typedef struct httpr_client_t {
+	struct evbuffer *buff;
+	char *firstline;
+	int need_host;
+	int has_host;
+} httpr_client;
+
+
+static void httpr_client_init(redsocks_client *client)
+{
+	httpr_client *httpr = (void*)(client +1);
+
+	if (client->instance->config.login)
+		log_error("login is ignored for http-relay connections");
+	
+	if (client->instance->config.password)
+		log_error("password is ignored for http-relay connections");
+	
+	client->state = httpr_new;
+	memset(httpr, 0, sizeof(*httpr));
+}
+
+static void httpr_client_fini(redsocks_client *client)
+{
+	httpr_client *httpr = (void*)(client +1);
+
+	if (httpr->buff) {
+		evbuffer_free(httpr->buff);
+		httpr->buff = 0;
+	}
+}
+
+static void httpr_relay_write_cb(struct bufferevent *buffev, void *_arg)
+{
+	redsocks_client *client = _arg;
+	httpr_client *httpr = (void*)(client +1);
+	int len;
+
+	assert(httpr->buff);
+
+	len = bufferevent_write_buffer(client->relay, httpr->buff);
+	// free is done either at _start_relay or at _drop_client
+
+	if (len >= 0) {
+		redsocks_start_relay(client);
+	}
+	else {
+		log_errno("bufferevent_write_buffer");
+		redsocks_drop_client(client);
+	}
+}
+
+// drops client on failure
+static int httpr_append_header(redsocks_client *client, char *line)
+{
+	httpr_client *httpr = (void*)(client +1);
+	int error;
+
+	error = evbuffer_add(httpr->buff, line, strlen(line));
+	if (!error)
+		evbuffer_add(httpr->buff, "\x0d\x0a", 2);
+	if (error) {
+		log_errno("evbuffer_add");
+	}
+	return error;
+}
+
+// This function is not reenterable
+static char *fmt_http_host(struct sockaddr_in addr)
+{
+	static char host[] = "123.123.123.123:12345";
+	if (ntohs(addr.sin_port) == 80)
+		return inet_ntoa(addr.sin_addr);
+	else {
+		snprintf(host, sizeof(host), 
+				"%s:%u",
+				inet_ntoa(addr.sin_addr),
+				ntohs(addr.sin_port)
+				);
+		return host;
+	}
+}
+
+static int httpr_toss_http_firstline(redsocks_client *client)
+{
+	httpr_client *httpr = (void*)(client +1);
+	char *uri = NULL;
+	struct evbuffer *buff = NULL;
+	char *host = fmt_http_host(client->destaddr);
+	
+	assert(httpr->firstline);
+	
+	uri = strchr(httpr->firstline, ' ');
+	if (uri) 
+		uri += 1; // one char further
+	else {
+		log_error("malformed request came");
+		goto fail;
+	}
+
+	buff = evbuffer_new();
+	if (!buff) {
+		log_error("evbuffer_new");
+		goto fail;
+	}
+
+	if (evbuffer_add(buff, httpr->firstline, uri - httpr->firstline) < 0)
+		goto addition_fail;
+	if (evbuffer_add(buff, "http://", 7) < 0)
+		goto addition_fail;
+	if (evbuffer_add(buff, host, strlen(host)) < 0)
+		goto addition_fail;
+	if (evbuffer_add(buff, uri, strlen(uri)) < 0)
+		goto addition_fail;
+	if (evbuffer_add(buff, "\x0d\x0a", 2) < 0)
+		goto addition_fail;
+	if (evbuffer_add_buffer(buff, httpr->buff) < 0)
+		goto addition_fail;
+
+	evbuffer_free(httpr->buff);
+	httpr->buff = buff;
+	return 0;
+	
+addition_fail:
+	log_error("evbuffer_add");
+fail:
+	if (buff)
+		evbuffer_free(buff);
+	return -1;
+}
+
+static void httpr_client_read_cb(struct bufferevent *buffev, void *_arg)
+{
+	redsocks_client *client = _arg;
+	httpr_client *httpr = (void*)(client +1);
+	char *line = NULL;
+	int connect_relay = 0;
+	
+	while ( (line = evbuffer_readline(buffev->input)) && !connect_relay) {
+		int skip_line = 0;
+		int do_drop = 0;
+
+		if (strlen(line) > 0) {
+			if (EVBUFFER_LENGTH(httpr->buff) == 0) { // FOO uri HTTP/3.14
+				char *space = strchr(line, ' ');
+
+				if (space)
+					httpr->need_host = (space[1] == '/' || space[1] == '*');
+
+				if (httpr->need_host) {
+					httpr->firstline = line;
+					line = 0;
+				}
+			}
+			else if (strncasecmp(line, "Host", 4) == 0)
+				httpr->has_host = 1;
+			else if (strncasecmp(line, "Proxy-Connection", 16) == 0)
+				skip_line = 1;
+			else if (strncasecmp(line, "Connection", 10) == 0)
+				skip_line = 1;
+		}
+		else { // last line of request
+			if (httpr->firstline) {
+				if (httpr_toss_http_firstline(client) < 0)
+					do_drop = 1;
+			}
+
+			if (httpr->need_host && !httpr->has_host) {
+				char host[32]; // "Host: 123.456.789.012:34567"
+				strncpy(host, "Host: ", sizeof(host));
+				strncat(host, fmt_http_host(client->destaddr), sizeof(host));
+				if (httpr_append_header(client, host) < 0)
+					do_drop = 1;
+			}
+
+			if (httpr_append_header(client, "Proxy-Connection: close") < 0)
+				do_drop = 1;
+
+			if (httpr_append_header(client, "Connection: close") < 0)
+				do_drop = 1;
+
+			connect_relay = 1;
+		}
+
+		if (line && !skip_line)
+			if (httpr_append_header(client, line) < 0)
+				do_drop = 1;
+		
+		free(line);
+
+		if (do_drop) {
+			redsocks_drop_client(client);
+			return;
+		}
+	}
+	
+	if (connect_relay)
+		redsocks_connect_relay(client);
+}
+
+static void httpr_connect_relay(redsocks_client *client)
+{
+	httpr_client *httpr = (void*)(client +1);
+	int error;
+
+	httpr->buff = evbuffer_new();
+	if (!httpr->buff) {
+		log_errno("evbuffer_new");
+		redsocks_drop_client(client);
+	}
+	
+	client->client->readcb = httpr_client_read_cb;
+	error = bufferevent_enable(client->client, EV_READ);
+	if (error) {
+		log_errno("bufferevent_enable");
+		redsocks_drop_client(client);
+	}
+}
+
+relay_subsys http_relay_subsys = 
+{
+	.name          = "http-relay",
+	.payload_len   = sizeof(httpr_client),
+	.init          = httpr_client_init,
+	.fini          = httpr_client_fini,
+	.connect_relay = httpr_connect_relay,
+	.writecb       = httpr_relay_write_cb,
+};
+
+/* vim:set tabstop=4 softtabstop=4 shiftwidth=4: */
+/* vim:set foldmethod=marker foldlevel=32 foldmarker={,}: */

redsocks.c

@@ -42,11 +42,13 @@ static int fcntl_nonblock(int fd)
 }
 
 extern relay_subsys http_connect_subsys;
+extern relay_subsys http_relay_subsys;
 extern relay_subsys socks4_subsys;
 extern relay_subsys socks5_subsys;
 static relay_subsys *relay_subsystems[] = 
 {
 	&http_connect_subsys,
+	&http_relay_subsys,
 	&socks4_subsys,
 	&socks5_subsys,
 };

redsocks.h

@@ -55,6 +55,7 @@ typedef struct redsocks_client_t {
 
 
 void redsocks_drop_client(redsocks_client *client);
+void redsocks_connect_relay(redsocks_client *client);
 void redsocks_start_relay(redsocks_client *client);
 
 typedef int (*size_comparator)(size_t a, size_t b);