doc: document proxy scheme

Signed-off-by: hexian000 <hexian000@outlook.com>

API.md

@@ -63,8 +63,8 @@ Trigger a full GC.
 **Synopsis**
 
 ```Lua
-function ruleset.resolve(domain, source)
-    return "www.example.org:80", "http://203.0.113.1:8080", ..., "[2001:DB8::1]:1080"
+function ruleset.resolve(domain)
+    return "www.example.org:80", "203.0.113.1:1080", ..., "[2001:DB8::1]:1080"
 end
 ```
 
@@ -78,7 +78,6 @@ Process a host name request. Specifically:
 **Params**
 
 - `domain`: full qualified domain name and port, like `"www.example.org:80"`
-- `source`: the address and port of the client making this request, like `"203.0.113.1:54321"`
 
 **Returns**
 
@@ -87,20 +86,14 @@ Process a host name request. Specifically:
 - `addr, proxyN, ..., proxy1`: forward the request through proxy chain
 - `nil`: reject the request
 
-Proxy protocols can be specified in URI scheme:
-
-- `203.0.113.1:1080`: SOCKS4A is the default
-- `socks4a://203.0.113.1:1080`: if making IPv4 request, this protocol is compatible with standard SOCKS4
-- `socks5://203.0.113.1:1080`: name resolution is performed remotely
-- `http://203.0.113.1:1080`: HTTP CONNECT proxy
 
 ### ruleset.route
 
 **Synopsis**
 
 ```Lua
-function ruleset.route(addr, source)
-    return "www.example.org:80", "http://203.0.113.1:8080", ..., "[2001:DB8::1]:1080"
+function ruleset.route(addr)
+    return "www.example.org:80", "203.0.113.1:1080", ..., "[2001:DB8::1]:1080"
 end
 ```
 
@@ -113,7 +106,6 @@ Process an IPv4 request. Specifically:
 **Params**
 
 - `addr`: address and port, like `"203.0.113.1:80"`
-- `source`: the address and port of the client making this request, like `"203.0.113.1:54321"`
 
 **Returns**
 
@@ -125,8 +117,8 @@ See [ruleset.resolve](#rulesetresolve)
 **Synopsis**
 
 ```Lua
-function ruleset.route6(addr, source)
-    return "www.example.org:80", "http://203.0.113.1:8080", ..., "[2001:DB8::1]:1080"
+function ruleset.route6(addr)
+    return "www.example.org:80", "203.0.113.1:1080", ..., "[2001:DB8::1]:1080"
 end
 ```
 
@@ -139,7 +131,6 @@ Process an IPv6 request. Specifically:
 **Params**
 
 - `addr`: address and port, like `"[2001:DB8::1]:80"`
-- `source`: the address and port of the client making this request, like `"203.0.113.1:54321"`
 
 **Returns**
 

src/dialer.c

@@ -135,7 +135,9 @@ bool dialreq_proxy(
 		uri.host = uri.defacto;
 	} else if (strcmp(uri.scheme, "http") == 0) {
 		protocol = PROTO_HTTP;
-	} else if (strcmp(uri.scheme, "socks4a") == 0) {
+	} else if (
+		strcmp(uri.scheme, "socks4") == 0 ||
+		strcmp(uri.scheme, "socks4a") == 0) {
 		protocol = PROTO_SOCKS4A;
 	} else if (strcmp(uri.scheme, "socks5") == 0) {
 		protocol = PROTO_SOCKS5;

src/http_proxy.c

@@ -2,7 +2,6 @@
 #include "conf.h"
 #include "ruleset.h"
 
-#include "utils/check.h"
 #include <ev.h>
 
 static void xfer_state_cb(struct ev_loop *loop, void *data)