Common Gateway Interface如雷貫耳，遺憾的是一直以來都沒玩過CGI，今天嘗試一把。Tomcat可以是玩CGI的，但得改下配置。為了方便，直接使用一款更輕量級的web服務器lighttpd來跑，。
先把lighttpd安裝一下：直接使用linux的包管理器，先安裝一個epel軟件倉庫
yum install epel-release
從這個倉庫里拿到lighttpd並安裝
yum install lighttpd
安裝好web服務器后就可以來寫CGI代碼了，可以用各種語言來寫，這里選擇C。C編譯后本身就是可執行文件，所以我們得把CGI的配置改一改：
[root@iZbp11ahvmlfioymoo7u3bZ ~]# vi /etc/lighttpd/conf.d/cgi.conf ####################################################################### ## ## CGI modules ## --------------- ## ## See https://redmine.lighttpd.net/projects/lighttpd/wiki/docs_modcgi ## server.modules += ( "mod_cgi" ) ## ## Plain old CGI handling ## ## For PHP don't forget to set cgi.fix_pathinfo = 1 in the php.ini. ## cgi.assign = ( ".pl" => "/usr/bin/perl", ".cgi" => "/usr/bin/perl", ".rb" => "/usr/bin/ruby", ".erb" => "/usr/bin/eruby", ".py" => "/usr/bin/python" ) ## ## to get the old cgi-bin behavior of apache ## ## Note: make sure that mod_alias is loaded if you uncomment the ## next line. (see modules.conf) ## #alias.url += ( "/cgi-bin" => server_root + "/cgi-bin" ) #$HTTP["url"] =~ "^/cgi-bin" { # cgi.assign = ( "" => "" ) #} ## #######################################################################
這里將.cgi改為
".cgi" => "",
以上表示指定解析程序為空，這樣對於帶擴展名為.cgi的請求，不需要特定解析程序（比如用/bin/sh/perl）就能執行CGI。接着到/var/www/lighttpd目錄，用C寫一個簡單例子
// A "hello world" page #include <stdio.h> #include <stdlib.h> #include <string.h> #define INCR_LEN 10 char *getValue(char *, char **);// get the param value char **getParameters(char *, char **);// get the array of params and values int main(void) { char **pQuery; char *pParam; char *name; char *city; pParam = getenv("QUERY_STRING"); char *pStr = malloc(strlen(pParam)+1); memcpy(pStr, pParam, strlen(pParam)+1); pQuery = getParameters(pStr, pQuery); name = getValue("name", pQuery); city = getValue("city", pQuery); printf("Content-Type:text/html\n\n");// print html puts("<html>"); puts("<head><title>An HTML Page From a CGI</title></head>"); puts("<body><br>"); puts("<p><h2>Hello world!</h2></p>"); printf("<p>Your name is :%s</p>\n", name); printf("<p>Your city is :%s</p>\n", city); puts("</body>"); puts("</html>"); return 0; } char **getParameters(char *pTemp, char **pQuery) { char **pArrayTemp = NULL; pQuery = calloc(INCR_LEN, sizeof(char *)); char *pParamIndex = NULL; int i = 0; int count_max = INCR_LEN; while((pParamIndex = strchr(pTemp,'&')) != NULL) { if(i == count_max) // array reach max(10) need more memory { count_max += INCR_LEN; pArrayTemp = realloc(pQuery, count_max*sizeof(char*)); if(!pArrayTemp) { exit(1); } pQuery = pArrayTemp; } *(pQuery+i) = malloc(pParamIndex - pTemp + 1); strncpy(*(pQuery+i), pTemp, pParamIndex - pTemp); strncpy(pTemp, pParamIndex+1, strlen(pTemp) - (pParamIndex-pTemp) + 1); i++; } *(pQuery+i) = malloc(strlen(pTemp) + 1); strncpy(*(pQuery+i), pTemp, strlen(pTemp)+1); return pQuery; } char *getValue(char *pParameter, char **pParamValues) { char *pValue = NULL; for(; *pParamValues!=NULL; pParamValues++) { if(strstr(*pParamValues, pParameter)) { pValue = strchr(*pParamValues, '='); if(pValue) return pValue+1; } } return NULL; }
把上面的C編譯一下：
gcc hello.c -o hello.cgi
最后把端口號由80改為其他端口號如8089，避免啟動時與原有端口沖突。
vi /etc/lighttpd/lighttpd.conf
找到server.port后，將80改為8089。接着啟動lighttpd服務器：
systemctl start lighttpd
再看下是否已經啟起來了：
systemctl status lighttpd ● lighttpd.service - Lightning Fast Webserver With Light System Requirements Loaded: loaded (/usr/lib/systemd/system/lighttpd.service; disabled; vendor preset: disabled) Active: active (running) since Thu 2019-04-18 14:18:04 CST; 2s ago Main PID: 30237 (lighttpd) CGroup: /system.slice/lighttpd.service └─30237 /usr/sbin/lighttpd -D -f /etc/lighttpd/lighttpd.conf Apr 18 14:18:04 iZbp11ahvmlfioywlf7u3bZ systemd[1]: Started Lightning Fast Webserver With Light System Requirements. Apr 18 14:18:04 iZbp11ahvmlfioywlf7u3bZ lighttpd[30237]: 2019-04-18 14:18:04: (network.c.166) warning: please use server.use-ipv6 only for hostnames, not wi...Y changes Apr 18 14:18:04 iZbp11ahvmlfioywlf7u3bZ lighttpd[30237]: 2019-04-18 14:18:04: (server.c.1380) can't have more connections than fds/2: 1024 1024
我們看到已經啟動成功了，但提示要用ipv6的地址來訪問，但我想用ipv4，所以把它改掉，再次/etc/lighttpd/lighttpd.conf -> 找到server.use-ipv6 = "enable" -> 將enable改為disable -> systemctl restart lighttpd
然后我們通過ip:8089/index.html訪問lighttpd自帶的歡迎頁：
再去訪問我們編譯好的hello.cgi，發現頁面可以訪問，卻啥都沒有，瀏覽器把頁面直接下載了而不是渲染出來。咋回事呢？原來這時候的cgi文件瀏覽器是無法解析的，必須要去modules.conf里打開cgi：vi /etc/lighttpd/modules.conf -> 找到 #include "conf.d/cgi.conf" -> 將前面的#號刪掉 -> 重啟lighttpd systemctl restart lighttpd
再次訪問我們的hello.cgi，這次ok了
