Mongoose http server 例子-编程知识

今天抽了点时间看了一下 mongoose的源码， github 地址，发现跟以前公司内部使用的不太一样，这里正好利用其 http server 例子来看一下。以前的 http message 结构体是这样的：

/* HTTP message */
struct http_message {struct mg_str message; /* Whole message: request line + headers + body */struct mg_str body;    /* Message body. 0-length for requests with no body *//* HTTP Request line (or HTTP response line) */struct mg_str method; /* "GET" */struct mg_str uri;    /* "/my_file.html" */struct mg_str proto;  /* "HTTP/1.1" -- for both request and response *//* For responses, code and response status message are set */int resp_code;struct mg_str resp_status_msg;/** Query-string part of the URI. For example, for HTTP request*    GET /foo/bar?param1=val1&param2=val2*    |    uri    |     query_string     |** Note that question mark character doesn't belong neither to the uri,* nor to the query_string*/struct mg_str query_string;/* Headers */struct mg_str header_names[MG_MAX_HTTP_HEADERS];struct mg_str header_values[MG_MAX_HTTP_HEADERS];
};

github 上的源码的http message 结构体是这样的：

struct mg_http_message {struct mg_str method, uri, query, proto;             // Request/response linestruct mg_http_header headers[MG_MAX_HTTP_HEADERS];  // Headersstruct mg_str body;                                  // Bodystruct mg_str head;                                  // Request + headersstruct mg_str chunk;    // Chunk for chunked encoding,  or partial bodystruct mg_str message;  // Request + headers + body
};

很明显现在的头部消息使用了 mg_http_header 结构体，它的定义是这样的：

struct mg_http_header {struct mg_str name;   // Header namestruct mg_str value;  // Header value
};

今天使用的是mongoose 自带的例子，位于源码目录的 examples/http-server 下的 main.c，因为我使用了c++的，所以我自己创建了目录 myExample/http_server，把它的 main.c 换成了 main.cpp，makefile 使用自己的，在编译的时候解决一下编译问题即可。

自己写的Makefile

#中间文件存放目录，如.o 和 .d 文件
COMPILE_DIR = compile
BIN_DIR = bin# 可编译arm版本
#CROSS = arm-himix200-linux-
CC = gcc 
CPP = $(CROSS)g++ -std=c++11
CFLAGS = -Werror -g
CFLAGS += -I../../
CPP_SRCS = $(wildcard *.cpp)
CPP_OBJS = $(patsubst %.cpp, $(COMPILE_DIR)/%.o, $(CPP_SRCS))
CPP_DEP = $(patsubst %.cpp, $(COMPILE_DIR)/%.cpp.d, $(CPP_SRCS))OBJS = $(CPP_OBJS) $(C_OBJS)
DEP_ALL = $(CPP_DEP) $(C_DEP)$(shell if [ ! -d $(COMPILE_DIR) ]; then mkdir $(COMPILE_DIR); fi)
$(shell if [ ! -d $(BIN_DIR) ]; then mkdir $(BIN_DIR); fi)BIN =
ifeq ($(target), ) #如果是空的
BIN = httpServer
else
BIN := $(target)
endifTARGET=$(BIN_DIR)/$(BIN)all: $(TARGET)-include $(DEP_ALL)$(TARGET): $(OBJS) $(COMPILE_DIR)/mongoose.o$(CPP) $(CFLAGS) $^ -o $@ $(COMPILE_DIR)/%.o: %.cpp $(COMPILE_DIR)/%.cpp.d$(CPP) $(CFLAGS) -c $< -o $@$(COMPILE_DIR)/%.cpp.d: %.cpp$(CPP) $(CFLAGS) -MM -E -c $< -o $@@sed 's/.*\.o/$(subst /,\/,$(dir $@))&/g' $@ > $@.tmp@mv $@.tmp $@$(COMPILE_DIR)/mongoose.o: ../../mongoose.c$(CC) $(CFLAGS) -c $< -o $@$(COMPILE_DIR)/%.c.d: %.c$(CC) $(CFLAGS) -MM -E -c $< -o $@@sed 's/.*\.o/$(subst /,\/,$(dir $@))&/g' $@ > $@.tmp@mv $@.tmp $@.PHONY: clean
clean:rm -rf $(COMPILE_DIR) $(BIN_DIR)

同时把main.cpp里的书写格式也改了，还是习惯一行行的看代码：

// Copyright (c) 2020 Cesanta Software Limited
// All rights reserved#include <signal.h>
#include "mongoose.h"static int s_debug_level = MG_LL_INFO;
static const char *s_root_dir = ".";
static const char *s_listening_address = "http://0.0.0.0:8190";
static const char *s_enable_hexdump = "no";
static const char *s_ssi_pattern = "#.html";// Handle interrupts, like Ctrl-C
static int s_signo;
static void signal_handler(int signo) 
{s_signo = signo;
}// Event handler for the listening connection.
// Simply serve static files from `s_root_dir`
static void cb(struct mg_connection *c, int ev, void *ev_data, void *fn_data) 
{if (ev == MG_EV_HTTP_MSG) {struct mg_http_message *hm = (mg_http_message *)ev_data, tmp = {0};struct mg_str unknown = mg_str_n("?", 1), *cl;struct mg_http_serve_opts opts = {0};//不能用ptr直接打印，需要根据lenMG_INFO(("method(%d): %s, uri(%d): %s, query(%d): %s, proto(%d): %s", hm->method.len, hm->method.ptr, hm->uri.len, hm->uri.ptr, hm->query.len, hm->query.ptr, hm->proto.len, hm->proto.ptr));MG_INFO(("method ptr: %p, uri ptr: %p, query ptr: %p, proto ptr: %p\n", hm->method.ptr, hm->uri.ptr, hm->query.ptr, hm->proto.ptr));//设置目录起点opts.root_dir = s_root_dir;opts.ssi_pattern = s_ssi_pattern;mg_http_serve_dir(c, hm, &opts);mg_http_parse((char *) c->send.buf, c->send.len, &tmp);cl = mg_http_get_header(&tmp, "Content-Length");if (cl == NULL) {cl = &unknown;}MG_INFO(("%.*s %.*s %.*s %.*s", (int) hm->method.len, hm->method.ptr,(int) hm->uri.len, hm->uri.ptr, (int) tmp.uri.len, tmp.uri.ptr,(int) cl->len, cl->ptr));}(void) fn_data;
}static void usage(const char *prog) 
{fprintf(stderr,"Mongoose v.%s\n""Usage: %s OPTIONS\n""  -H yes|no - enable traffic hexdump, default: '%s'\n""  -S PAT    - SSI filename pattern, default: '%s'\n""  -d DIR    - directory to serve, default: '%s'\n""  -l ADDR   - listening address, default: '%s'\n""  -v LEVEL  - debug level, from 0 to 4, default: %d\n",MG_VERSION, prog, s_enable_hexdump, s_ssi_pattern, s_root_dir,s_listening_address, s_debug_level);exit(EXIT_FAILURE);
}int main(int argc, char *argv[]) 
{char path[MG_PATH_MAX] = ".";struct mg_mgr mgr;struct mg_connection *c;int i;// Parse command-line flagsfor (i = 1; i < argc; i++) {if (strcmp(argv[i], "-d") == 0) {s_root_dir = argv[++i];} else if (strcmp(argv[i], "-H") == 0) {s_enable_hexdump = argv[++i];} else if (strcmp(argv[i], "-S") == 0) {s_ssi_pattern = argv[++i];} else if (strcmp(argv[i], "-l") == 0) {s_listening_address = argv[++i];} else if (strcmp(argv[i], "-v") == 0) {s_debug_level = atoi(argv[++i]);} else {usage(argv[0]);}}// Root directory must not contain double dots. Make it absolute// Do the conversion only if the root dir spec does not contain overridesif (strchr(s_root_dir, ',') == NULL) {realpath(s_root_dir, path);s_root_dir = path;}// Initialise stuffsignal(SIGINT, signal_handler);signal(SIGTERM, signal_handler);mg_log_set(s_debug_level);mg_mgr_init(&mgr);if ((c = mg_http_listen(&mgr, s_listening_address, cb, &mgr)) == NULL) {MG_ERROR(("Cannot listen on %s. Use http://ADDR:PORT or :PORT", s_listening_address));exit(EXIT_FAILURE);}if (mg_casecmp(s_enable_hexdump, "yes") == 0) {c->is_hexdumping = 1;}// Start infinite event loopMG_INFO(("Mongoose version : v%s", MG_VERSION));MG_INFO(("Listening on     : %s", s_listening_address));MG_INFO(("Web root         : [%s]", s_root_dir));while (s_signo == 0) {mg_mgr_poll(&mgr, 1000);}mg_mgr_free(&mgr);MG_INFO(("Exiting on signal %d", s_signo));return 0;
}

在实际使用的时候需要注意 struct mg_str 结构体，如 mg_http_message 中的 method, uri, query, proto 等，代码里我只是好奇地想打印一下这些数据，然而结果并不是我想要的，如：

        MG_INFO(("method(%d): %s, uri(%d): %s, query(%d): %s, proto(%d): %s", hm->method.len, hm->method.ptr, hm->uri.len, hm->uri.ptr, hm->query.len, hm->query.ptr, hm->proto.len, hm->proto.ptr));MG_INFO(("method ptr: %p, uri ptr: %p, query ptr: %p, proto ptr: %p\n", hm->method.ptr, hm->uri.ptr, hm->query.ptr, hm->proto.ptr));

打印 mg_str 的时候使用了其 ptr 指针，而打印出这些指针可以看到它们指向的是连续的一个地址：

[2023/08/10 14:52:21 510890 Info] main.cpp:32:cb method ptr: 0x1f30580, uri ptr: 0x1f30584, query ptr: 0x0, proto ptr: 0x1f30586

HTTP message format

0x1f30580 + 3(method 的长度) + 1(一个空格) = 0x1f30584，0x1f30584 + 1(uri的长度)+1(一个空格) = 0x1f30586。

使用了 std::string

        std::string method(hm->method.ptr, hm->method.len);std::string uri(hm->uri.ptr, hm->uri.len);std::string proto(hm->proto.ptr, hm->proto.len);MG_INFO(("method: %s, uri: %s, proto: %s\n", method.c_str(), uri.c_str(), proto.c_str()));