http-server.c
创建一个简单的http服务端
/*
A trivial static http webserver using Libevent's evhttp.
This is not the best code in the world, and it does some fairly stupid stuff
that you would never want to do in a production webserver. Caveat hackor!
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#ifdef WIN32
#include <winsock2.h>
#include <ws2tcpip.h>
#include <windows.h>
#include <io.h>
#include <fcntl.h>
#ifndef S_ISDIR
#define S_ISDIR(x) (((x) & S_IFMT) == S_IFDIR)
#endif
#else
#include <sys/stat.h>
#include <sys/socket.h>
#include <signal.h>
#include <fcntl.h>
#include <unistd.h>
#include <dirent.h>
#endif
#include <event2/event.h>
#include <event2/http.h>
#include <event2/buffer.h>
#include <event2/util.h>
#include <event2/keyvalq_struct.h>
#ifdef _EVENT_HAVE_NETINET_IN_H
#include <netinet/in.h>
# ifdef _XOPEN_SOURCE_EXTENDED
# include <arpa/inet.h>
# endif
#endif
/* Compatibility for possible missing IPv6 declarations */
#include "../util-internal.h"
#ifdef WIN32
#define stat _stat
#define fstat _fstat
#define open _open
#define close _close
#define O_RDONLY _O_RDONLY
#endif
char uri_root[512];
static const struct table_entry {
const char *extension;
const char *content_type;
} content_type_table[] = {
{ "txt", "text/plain" },
{ "c", "text/plain" },
{ "h", "text/plain" },
{ "html", "text/html" },
{ "htm", "text/htm" },
{ "css", "text/css" },
{ "gif", "image/gif" },
{ "jpg", "image/jpeg" },
{ "jpeg", "image/jpeg" },
{ "png", "image/png" },
{ "pdf", "application/pdf" },
{ "ps", "application/postsript" },
{ NULL, NULL },
};
/* Try to guess a good content-type for 'path' */
static const char *
guess_content_type(const char *path)
{
const char *last_period, *extension;
const struct table_entry *ent;
last_period = strrchr(path, '.');
if (!last_period || strchr(last_period, '/'))
goto not_found; /* no exension */
extension = last_period + 1;
for (ent = &content_type_table[0]; ent->extension; ++ent) {
if (!evutil_ascii_strcasecmp(ent->extension, extension))
return ent->content_type;
}
not_found:
return "application/misc";
}
/* Callback used for the /dump URI, and for every non-GET request:
* dumps all information to stdout and gives back a trivial 200 ok */
static void
dump_request_cb(struct evhttp_request *req, void *arg)
{
const char *cmdtype;
struct evkeyvalq *headers;
struct evkeyval *header;
struct evbuffer *buf;
//获取当前http请求类型
switch (evhttp_request_get_command(req)) {
case EVHTTP_REQ_GET: cmdtype = "GET"; break;
case EVHTTP_REQ_POST: cmdtype = "POST"; break;
case EVHTTP_REQ_HEAD: cmdtype = "HEAD"; break;
case EVHTTP_REQ_PUT: cmdtype = "PUT"; break;
case EVHTTP_REQ_DELETE: cmdtype = "DELETE"; break;
case EVHTTP_REQ_OPTIONS: cmdtype = "OPTIONS"; break;
case EVHTTP_REQ_TRACE: cmdtype = "TRACE"; break;
case EVHTTP_REQ_CONNECT: cmdtype = "CONNECT"; break;
case EVHTTP_REQ_PATCH: cmdtype = "PATCH"; break;
default: cmdtype = "unknown"; break;
}
printf("Received a %s request for %s\nHeaders:\n",
cmdtype, evhttp_request_get_uri(req)); //evhttp_request_get_uri 获取当前请求完整uri
headers = evhttp_request_get_input_headers(req); //获取请求头信息，使用链表
for (header = headers->tqh_first; header;
header = header->next.tqe_next) {
printf(" %s: %s\n", header->key, header->value);
}
buf = evhttp_request_get_input_buffer(req);//
puts("Input data: <<<");
while (evbuffer_get_length(buf)) {
int n;
char cbuf[128];
n = evbuffer_remove(buf, cbuf, sizeof(cbuf));//从buf 中移动128个字节，并拷贝到cbuf
if (n > 0)
(void) fwrite(cbuf, 1, n, stdout); //打印日志
}
puts(">>>");
evhttp_send_reply(req, 200, "OK", NULL);//返回200
}
/* This callback gets invoked when we get any http request that doesn't match
* any other callback. Like any evhttp server callback, it has a simple job:
* it must eventually call evhttp_send_error() or evhttp_send_reply().
*/
static void
send_document_cb(struct evhttp_request *req, void *arg)
{
struct evbuffer *evb = NULL;
const char *docroot = arg;
const char *uri = evhttp_request_get_uri(req);//获取当前uri
struct evhttp_uri *decoded = NULL;
const char *path;
char *decoded_path;
char *whole_path = NULL;
size_t len;
int fd = -1;
struct stat st;
if (evhttp_request_get_command(req) != EVHTTP_REQ_GET) { //get请求
dump_request_cb(req, arg);
return;
}
printf("Got a GET request for <%s>\n", uri);
/* Decode the URI */
decoded = evhttp_uri_parse(uri); //解码当前uri,如果失败，则返回null
if (!decoded) {
printf("It's not a good URI. Sending BADREQUEST\n");
evhttp_send_error(req, HTTP_BADREQUEST, 0); //返回错误
return;
}
/* Let's see what path the user asked for. */
path = evhttp_uri_get_path(decoded);//返回路径
if (!path) path = "/";
/* We need to decode it, to see what path the user really wanted. */
decoded_path = evhttp_uridecode(path, 0, NULL); //解码uri路径
if (decoded_path == NULL)
goto err;
/* Don't allow any ".."s in the path, to avoid exposing stuff outside
* of the docroot. This test is both overzealous and underzealous:
* it forbids aceptable paths like "/this/one..here", but it doesn't
* do anything to prevent symlink following." */
if (strstr(decoded_path, "..")) //strstr 判断字符串str2是否是str1的子串。如果是，则该函数返回str2在str1中首次出现的地址；否则，返回NULL。
goto err;
len = strlen(decoded_path)+strlen(docroot)+2;
if (!(whole_path = malloc(len))) {
perror("malloc");
goto err;
}
evutil_snprintf(whole_path, len, "%s/%s", docroot, decoded_path);
if (stat(whole_path, &st)<0) {
goto err;
}
/* This holds the content we're sending. */
evb = evbuffer_new(); //申请空间
if (S_ISDIR(st.st_mode)) {
/* If it's a directory, read the comments and make a little
* index page */
#ifdef WIN32
HANDLE d;
WIN32_FIND_DATAA ent;
char *pattern;
size_t dirlen;
#else
DIR *d;
struct dirent *ent;
#endif
const char *trailing_slash = "";
if (!strlen(path) || path[strlen(path)-1] != '/')
trailing_slash = "/";
#ifdef WIN32
dirlen = strlen(whole_path);
pattern = malloc(dirlen+3);
memcpy(pattern, whole_path, dirlen);
pattern[dirlen] = '\\';
pattern[dirlen+1] = '*';
pattern[dirlen+2] = '\0';
d = FindFirstFileA(pattern, &ent);
free(pattern);
if (d == INVALID_HANDLE_VALUE)
goto err;
#else
if (!(d = opendir(whole_path)))
goto err;
#endif
evbuffer_add_printf(evb, "<html>\n <head>\n"
" <title>%s</title>\n"
" <base href='%s%s%s'>\n"
" </head>\n"
" <body>\n"
" <h1>%s</h1>\n"
" <ul>\n",
decoded_path, /* XXX html-escape this. */
uri_root, path, /* XXX html-escape this? */
trailing_slash,
decoded_path /* XXX html-escape this */);
#ifdef WIN32
do {
const char *name = ent.cFileName;
#else
while ((ent = readdir(d))) {
const char *name = ent->d_name;
#endif
evbuffer_add_printf(evb,
" <li><a href=\"%s\">%s</a>\n",
name, name);/* XXX escape this */
#ifdef WIN32
} while (FindNextFileA(d, &ent));
#else
}
#endif
evbuffer_add_printf(evb, "</ul></body></html>\n");
#ifdef WIN32
FindClose(d);
#else
closedir(d);
#endif
evhttp_add_header(evhttp_request_get_output_headers(req), //增加返回头信息
"Content-Type", "text/html");
} else {
/* Otherwise it's a file; add it to the buffer to get
* sent via sendfile */
const char *type = guess_content_type(decoded_path);
if ((fd = open(whole_path, O_RDONLY)) < 0) {
perror("open");
goto err;
}
if (fstat(fd, &st)<0) {
/* Make sure the length still matches, now that we
* opened the file :/ */
perror("fstat");
goto err;
}
evhttp_add_header(evhttp_request_get_output_headers(req),
"Content-Type", type);
evbuffer_add_file(evb, fd, 0, st.st_size);
}
evhttp_send_reply(req, 200, "OK", evb); //返回内容
goto done;
err:
evhttp_send_error(req, 404, "Document was not found");
if (fd>=0)
close(fd);
done:
if (decoded)
evhttp_uri_free(decoded);
if (decoded_path)
free(decoded_path);
if (whole_path)
free(whole_path);
if (evb)
evbuffer_free(evb);
}
static void
syntax(void)
{
fprintf(stdout, "Syntax: http-server <docroot>\n");
}
int
main(int argc, char **argv)
{
struct event_base *base;
struct evhttp *http;
struct evhttp_bound_socket *handle;
unsigned short port = 0;
#ifdef WIN32
WSADATA WSAData;
WSAStartup(0x101, &WSAData);
#else
if (signal(SIGPIPE, SIG_IGN) == SIG_ERR)
return (1);
#endif
if (argc < 2) {
syntax();
return 1;
}
base = event_base_new();
if (!base) {
fprintf(stderr, "Couldn't create an event_base: exiting\n");
return 1;
}
/* Create a new evhttp object to handle requests. */
http = evhttp_new(base);
if (!http) {
fprintf(stderr, "couldn't create evhttp. Exiting.\n");
return 1;
}
/* The /dump URI will dump all requests to stdout and say 200 ok. */
evhttp_set_cb(http, "/dump", dump_request_cb, NULL); //对特定的URI注册回调事件
/* We want to accept arbitrary requests, so we need to set a "generic"
* cb. We can also add callbacks for specific paths. */
evhttp_set_gencb(http, send_document_cb, argv[1]); //没有注册的函数走此处
/* Now we tell the evhttp what port to listen on */
handle = evhttp_bind_socket_with_handle(http, "0.0.0.0", port); //监听端口
if (!handle) {
fprintf(stderr, "couldn't bind to port %d. Exiting.\n",
(int)port);
return 1;
}
{
/* Extract and display the address we're listening on. */
//获取和打印监听的地址
struct sockaddr_storage ss;
evutil_socket_t fd;
ev_socklen_t socklen = sizeof(ss);
char addrbuf[128];
void *inaddr;
const char *addr;
int got_port = -1;
fd = evhttp_bound_socket_get_fd(handle);
memset(&ss, 0, sizeof(ss));
if (getsockname(fd, (struct sockaddr *)&ss, &socklen)) {
perror("getsockname() failed");
return 1;
}
if (ss.ss_family == AF_INET) {
got_port = ntohs(((struct sockaddr_in*)&ss)->sin_port);
inaddr = &((struct sockaddr_in*)&ss)->sin_addr;
} else if (ss.ss_family == AF_INET6) {
got_port = ntohs(((struct sockaddr_in6*)&ss)->sin6_port);
inaddr = &((struct sockaddr_in6*)&ss)->sin6_addr;
} else {
fprintf(stderr, "Weird address family %d\n",
ss.ss_family);
return 1;
}
addr = evutil_inet_ntop(ss.ss_family, inaddr, addrbuf,
sizeof(addrbuf));
if (addr) {
printf("Listening on %s:%d\n", addr, got_port);
evutil_snprintf(uri_root, sizeof(uri_root),
"http://%s:%d",addr,got_port);
} else {
fprintf(stderr, "evutil_inet_ntop failed\n");
return 1;
}
}
event_base_dispatch(base);
return 0;
}