Merge pull request #43 from widgetii/http_server

Http server

.clang-format

@@ -0,0 +1,63 @@
+---
+Language:          Cpp
+BasedOnStyle:      LLVM
+
+AccessModifierOffset: -4
+
+AlignAfterOpenBracket: DontAlign
+AlignEscapedNewlinesLeft: true
+# AlignOperands: true
+AlignTrailingComments: true
+
+AllowAllParametersOfDeclarationOnNextLine: true
+AllowShortBlocksOnASingleLine: false
+AllowShortCaseLabelsOnASingleLine: false
+AllowShortFunctionsOnASingleLine: All
+AllowShortIfStatementsOnASingleLine: false
+AllowShortLoopsOnASingleLine: false
+
+AlwaysBreakAfterDefinitionReturnType: All
+AlwaysBreakBeforeMultilineStrings: false
+AlwaysBreakTemplateDeclarations: false
+
+# BinPackArguments: false
+# BinPackParameters: true
+
+BreakBeforeBinaryOperators: false
+BreakBeforeBraces: Custom
+BraceWrapping: { AfterFunction: true }
+BreakBeforeTernaryOperators: true
+BreakConstructorInitializersBeforeComma: true
+
+ColumnLimit:     80
+
+ContinuationIndentWidth: 4
+
+DerivePointerAlignment: false #XXX
+DisableFormat:   false
+ExperimentalAutoDetectBinPacking: false #XXX
+ForEachMacros:   [ LIST_FOREACH, SIMPLEQ_FOREACH, CIRCLEQ_FOREACH, TAILQ_FOREACH, TAILQ_FOREACH_REVERSE, HT_FOREACH ]
+
+IndentCaseLabels: false
+IndentFunctionDeclarationAfterType: false
+IndentWidth:     4
+IndentWrappedFunctionNames: false
+
+KeepEmptyLinesAtTheStartOfBlocks: true
+MaxEmptyLinesToKeep: 2
+
+PointerAlignment: Right #XXX
+
+# SpaceAfterCStyleCast: false
+SpaceBeforeAssignmentOperators: true
+SpaceBeforeParens: ControlStatements
+SpaceInEmptyParentheses: false
+SpacesBeforeTrailingComments: 1
+SpacesInAngles:  false
+SpacesInCStyleCastParentheses: false
+SpacesInParentheses: false
+Standard:        Cpp03
+TabWidth:        4
+UseTab:          Always
+SortIncludes:    false
+...

.gitignore

@@ -14,6 +14,8 @@
 /examples_R8/R8_echo_server
 /examples_R9/R9_multilookup
 /examples_R9/R9_dns_server
+/examples_R10/R10_simple_server
+/examples_R10/R10_static_server
 
 /tmpcode*
 

LibeventBook.txt

@@ -36,6 +36,5 @@ include::Ref8_listener.txt[]
 
 include::Ref9_dns.txt[]
 
-
-
+include::Ref10_http_server.txt[]
 

Makefile

@@ -19,6 +19,7 @@ GENERATED_CHAPTERS= \
 	Ref7_evbuffer.html \
 	Ref8_listener.html \
 	Ref9_dns.html \
+	Ref10_http_server.html \
 	license_bsd.html
 
 GENERATED_HTML = $(GENERATED_METAFILES) $(GENERATED_CHAPTERS)
@@ -42,6 +43,7 @@ examples:
 	cd examples_R6a && $(MAKE)
 	cd examples_R8 && $(MAKE)
 	cd examples_R9 && $(MAKE)
+	cd examples_R10 && $(MAKE)
 
 inline_examples:
 	./bin/build_examples.py *_*.txt
@@ -66,6 +68,7 @@ Ref6a_advanced_bufferevent.html: examples_R6a/*.c license.txt
 Ref7_evbuffer.html: license.txt
 Ref8_listener.html: examples_R8/*.c license.txt
 Ref9_dns.html: examples_R9/*.c license.txt
+Ref10_http_server.html: examples_R10/*.c license.txt
 
 clean:
 	rm -f *~

Ref10_http_server.txt

@@ -0,0 +1,57 @@
+:docinfo:
+
+Using the built-in HTTP server
+==============================
+
+include::license.txt[]
+
+:language: C
+
+The plain network-based Libevent interface is useful if you want to build native
+applications, but it is increasingly common to develop an application based
+around the HTTP protocol and a web page that loads, or more commonly dynamically
+reloads, information.
+
+To use the Libevent service, you use the same basic structure as already
+described for the main network event model, but instead of having to handle the
+network interfacing, the HTTP wrapper handles that for you.  This turns the
+entire process into the four function calls (initialize, start HTTP server, set
+HTTP callback function, and enter event loop), plus the contents of the callback
+function that will send data back. A very simple example is provided in the listing:
+
+
+.Example: A basic HTTP server
+[code,C]
+------
+include::examples_R10/R10_simple_server.c[]
+------
+
+Given the previous example, the basics of the code here should be relatively
+self-explanatory. The main elements are the evhttp_set_gencb() function, which
+sets the callback function to be used when an HTTP request is received, and the
+generic_request_handler() callback function itself, which populates the response
+buffer with a simple message to show success.
+
+The HTTP wrapper provides a wealth of different functionality. For example,
+there is a request parser that will extract the query arguments from a typical
+request (as you would use in a HTTP request), and you can also set different
+handlers to be triggered within different requested paths.
+
+Let's extend this example act Libevent as Nginx-like server for static content:
+
+.Example: A static HTTP server implementation
+[code,C]
+------
+include::examples_R10/R10_static_server.c[]
+------
+
+As you can see here we've replaced generic_request_handler() by specific
+send_file_to_user() handler which processes incoming request:
+
+* First it checks if HTTP command is equal to `GET` or `HEAD`
+
+* Then it parses request URI to extract request path and determine file path we
+  should handle by couple evhttp_request_get_uri()/evhttp_uri_parse() functions
+
+* After that it decoded URI string from something like `folder%2Fmy%20doc.txt`
+  to plain `folder/my doc.txt`

TOC.txt

@@ -24,6 +24,7 @@ A Libevent Reference Manual
 - link:Ref7_evbuffer.html[R7: Evbuffers: utility functionality for buffered IO]
 - link:Ref8_listener.html[R8: Connection listeners: accepting TCP connections]
 - link:Ref9_dns.html[R9: DNS for Libevent]
+- link:Ref10_http_server.html[R10: HTTP server]
 
 include::license.txt[]
 

examples_R10/Makefile

@@ -0,0 +1,23 @@
+
+CC=gcc
+CFLAGS=-g -Wall $(LEBOOK_CFLAGS)
+
+EXAMPLE_BINARIES=R10_simple_server R10_static_server
+
+all: examples
+
+examples: $(EXAMPLE_BINARIES)
+
+R10_simple_server: R10_simple_server.o
+	$(CC) $(CFLAGS) R10_simple_server.o -o R10_simple_server -levent
+
+R10_static_server: R10_static_server.o
+	$(CC) $(CFLAGS) R10_static_server.o -o R10_static_server -levent
+
+.c.o:
+	$(CC) $(CFLAGS) -c $<
+
+clean:
+	rm -f *~
+	rm -f *.o
+	rm -f $(EXAMPLE_BINARIES)

examples_R10/R10_simple_server.c

@@ -0,0 +1,49 @@
+#include <string.h>
+#include <signal.h>
+#include <event2/buffer.h>
+#include <event2/event.h>
+#include <event2/http.h>
+
+static void
+generic_request_handler(struct evhttp_request *req, void *ctx)
+{
+	struct evbuffer *reply = evbuffer_new();
+
+	evbuffer_add_printf(reply, "It works!");
+	evhttp_send_reply(req, HTTP_OK, NULL, reply);
+	evbuffer_free(reply);
+}
+
+static void
+signal_cb(evutil_socket_t fd, short event, void *arg)
+{
+	printf("%s signal received\n", strsignal(fd));
+	event_base_loopbreak(arg);
+}
+
+int
+main()
+{
+	ev_uint16_t http_port = 8080;
+	char *http_addr = "0.0.0.0";
+	struct event_base *base;
+	struct evhttp *http_server;
+	struct event *sig_int;
+
+	base = event_base_new();
+
+	http_server = evhttp_new(base);
+	evhttp_bind_socket(http_server, http_addr, http_port);
+	evhttp_set_gencb(http_server, generic_request_handler, NULL);
+
+	sig_int = evsignal_new(base, SIGINT, signal_cb, base);
+	event_add(sig_int, NULL);
+
+	printf("Listening requests on http://%s:%d\n", http_addr, http_port);
+
+	event_base_dispatch(base);
+
+	evhttp_free(http_server);
+	event_free(sig_int);
+	event_base_free(base);
+}