//	qmail-smtpd接受遠程主機的郵件并轉交給隊列處理程序qmail-queue來處理
//	由tcp-env.c啟動,完成郵件smtp命令的接收，并調用相應的處理程序
//	只接收郵件內容(mailfrom,mailto)并傳送給qmail-queue,并不對郵件進行轉發

#include "sig.h"#include "readwrite.h"#include "stralloc.h"#include "substdio.h"#include "alloc.h"#include "auto_qmail.h"#include "control.h"#include "received.h"#include "constmap.h"#include "error.h"#include "ipme.h"#include "ip.h"#include "qmail.h"#include "str.h"#include "fmt.h"#include "scan.h"#include "byte.h"#include "case.h"#include "env.h"#include "now.h"#include "exit.h"#include "rcpthosts.h"#include "timeoutread.h"#include "timeoutwrite.h"#include "commands.h"#define MAXHOPS 100unsigned int databytes = 0;		//郵件最大長度：0=無限int timeout = 1200;		//默認超時20分鐘
//	向網絡寫，超時值為control/timeoutsmtpd指定的值，沒有這個文件則取默認值20分鐘int safewrite(fd,buf,len) int fd; char *buf; int len;{  int r;  r = timeoutwrite(timeout,fd,buf,len);  if (r <= 0) _exit(1);  return r;}char ssoutbuf[512];substdio ssout = SUBSTDIO_FDBUF(safewrite,1,ssoutbuf,sizeof ssoutbuf);void flush() { substdio_flush(&ssout); }

//	void out(s) char *s 相當于 void out(char* s)void out(s) char *s; { substdio_puts(&ssout,s); }
//	錯誤處理函數void die_read() { _exit(1); }void die_alarm() { out("451 timeout (#4.4.2)\r\n"); flush(); _exit(1); }void die_nomem() { out("421 out of memory (#4.3.0)\r\n"); flush(); _exit(1); }void die_control() { out("421 unable to read controls (#4.3.0)\r\n"); flush(); _exit(1); }void die_ipme() { out("421 unable to figure out my IP addresses (#4.3.0)\r\n"); flush(); _exit(1); }void straynewline() { out("451 See http://pobox.com/~djb/docs/smtplf.html.\r\n"); flush(); _exit(1); }void err_bmf() { out("553 sorry, your envelope sender is in my badmailfrom list (#5.7.1)\r\n"); }void err_nogateway() { out("553 sorry, that domain isn't in my list of allowed rcpthosts (#5.7.1)\r\n"); }void err_unimpl() { out("502 unimplemented (#5.5.1)\r\n"); }void err_syntax() { out("555 syntax error (#5.5.4)\r\n"); }void err_wantmail() { out("503 MAIL first (#5.5.1)\r\n"); }void err_wantrcpt() { out("503 RCPT first (#5.5.1)\r\n"); }void err_noop() { out("250 ok\r\n"); }void err_vrfy() { out("252 send some mail, i'll try my best\r\n"); }void err_qqt() { out("451 qqt failure (#4.3.0)\r\n"); }stralloc greeting = {0};//end 錯誤處理函數
//	輸出提示信息*codevoid smtp_greet(code) char *code;{  substdio_puts(&ssout,code);  substdio_put(&ssout,greeting.s,greeting.len);}void smtp_help(){  out("214 qmail home page: http://pobox.com/~djb/qmail.html\r\n");}void smtp_quit(){  smtp_greet("221 "); out("\r\n"); flush(); _exit(0);}char *remoteip;	//遠端ip地址char *remotehost;	//遠端主機名char *remoteinfo;	//遠端信息char *local;	//本地主機char *relayclient;	//是否檢查rcpthosts文件stralloc helohost = {0};char *fakehelo; /* pointer into helohost, or 0 */void dohelo(arg) char *arg; {  if (!stralloc_copys(&helohost,arg)) die_nomem();   if (!stralloc_0(&helohost)) die_nomem(); 

  //fakehelo變量，如果helo參數指定的主機名與TCPREMOTEHOST環境變量中的主機名不同則
  //fakehelo的值為helo命令的參數指定的主機名。如果兩者相同則fekehelo為NULL；
  //data命令處理程式用到這個變量  fakehelo = case_diffs(remotehost,helohost.s) ? helohost.s : 0;}int liphostok = 0;stralloc liphost = {0};int bmfok = 0;

//	badmailfrom 用來指定不喜歡的發見人的郵件地址或者是域名
//該地址給主機發送郵件時將得到code 553，告知其是不受歡迎的發件人stralloc bmf = {0};		struct constmap mapbmf;void setup(){  char *x;  unsigned long u;   if (control_init() == -1) die_control();	//control/me

  //讀入歡迎信息greeting，如果不存在則從me文件復制  if (control_rldef(&greeting,"control/smtpgreeting",1,(char *) 0) != 1)    die_control();

  //讀入localiphost，如果文件不存在則從me文件復制  liphostok = control_rldef(&liphost,"control/localiphost",1,(char *) 0);  if (liphostok == -1) die_control();

  //讀control/timeoutsmtpd存入timeout,用于控制超時的情況  if (control_readint(&timeout,"control/timeoutsmtpd") == -1) die_control();  if (timeout <= 0) timeout = 1;  if (rcpthosts_init() == -1) die_control();
  //讀入badmailfrom文件存入bmf  bmfok = control_readfile(&bmf,"control/badmailfrom",0);  if (bmfok == -1) die_control();  if (bmfok)    if (!constmap_init(&mapbmf,bmf.s,bmf.len,0)) die_nomem(); 
  //讀入databytes文件存入databytes，如果該文件不存在，則將databytes的值設為0.  if (control_readint(&databytes,"control/databytes") == -1) die_control();  x = env_get("DATABYTES");  if (x) { scan_ulong(x,&u); databytes = u; }  if (!(databytes + 1)) --databytes; 
  //取tcp-environ環境變量，如果環境變量沒有設置，將它的值設置為unknow
  //這些信息在tcp-env文件中  remoteip = env_get("TCPREMOTEIP");  if (!remoteip) remoteip = "unknown";  local = env_get("TCPLOCALHOST");  if (!local) local = env_get("TCPLOCALIP");  if (!local) local = "unknown";  remotehost = env_get("TCPREMOTEHOST");  if (!remotehost) remotehost = "unknown";  remoteinfo = env_get("TCPREMOTEINFO");

  //從環境變量RELAYCLIENT讀入，如果RELAYCLIENT變量沒有設置那么relayclient將會是NULL  relayclient = env_get("RELAYCLIENT");  dohelo(remotehost);}stralloc addr = {0}; /* will be 0-terminated, if addrparse returns 1 */
//對命令參數arg進行郵件地址分析，并將分離出的email地址存入全局緩存addr，成功返回值1，
//失敗返回0int addrparse(arg)char *arg;{  int i;  char ch;  char terminator;  struct ip_address ip;  int flagesc;  int flagquoted; 
  //分離出郵件地址，例如：arg="",或arg=": email@eg.org"
  //執行下面這段程序后arg="email@eg.org"  terminator = '>';  i = str_chr(arg,'<');  if (arg[i])    arg += i + 1;  else { /* partner should go read rfc 821 */    terminator = ' ';    arg += str_chr(arg,':');    if (*arg == ':') ++arg;    while (*arg == ' ') ++arg;  }  /* strip source route */  if (*arg == '@') while (*arg) if (*arg++ == ':') break;  if (!stralloc_copys(&addr,"")) die_nomem();  flagesc = 0;  flagquoted = 0;  for (i = 0;ch = arg[i];++i) { /* copy arg to addr, stripping quotes */    if (flagesc) {      if (!stralloc_append(&addr,&ch)) die_nomem();      flagesc = 0;    }    else {      if (!flagquoted && (ch == terminator)) break;      switch(ch) {        case '\\': flagesc = 1; break;        case '"': flagquoted = !flagquoted; break;        default: if (!stralloc_append(&addr,&ch)) die_nomem();      }    }  }  /* could check for termination failure here, but why bother? */  if (!stralloc_append(&addr,"")) die_nomem();
  //將ip地址轉換為主機名：
  //如test@[10.0.6.21]轉換為test@host.mydomain.org
  //依據是control/localiphost文件中有host.mydomain.org  if (liphostok) {    i = byte_rchr(addr.s,addr.len,'@');    if (i < addr.len) /* if not, partner should go read rfc 821 */      if (addr.s[i + 1] == '[')		//比較是否是用[]括起來的ip地址        if (!addr.s[i + 1 + ip_scanbracket(addr.s + i + 1,&ip)])          if (ipme_is(&ip)) {            addr.len = i + 1;            if (!stralloc_cat(&addr,&liphost)) die_nomem();            if (!stralloc_0(&addr)) die_nomem();          }  }  if (addr.len > 900) return 0;		//地址太長，出錯返回  return 1;		//成功返回}
//簡單的垃圾郵件檢查，檢查全局緩沖區addr中的地址是否有在badmailfrom中定義，如果
//有則返回1，否則返回0.int bmfcheck(){  int j;  if (!bmfok) return 0;  if (constmap(&mapbmf,addr.s,addr.len - 1)) return 1;  j = byte_rchr(addr.s,addr.len,'@');  if (j < addr.len)    if (constmap(&mapbmf,addr.s + j,addr.len - j - 1)) return 1;  return 0;}
//檢查全局緩存addr中的郵件地址是否要進行轉發(依據control/rcpthosts文件)
//可以進行轉發返回1，拒絕轉發返回0int addrallowed(){  int r;