Zahn - Unix-Netzwerkprogramminerung mit Threads, Sockets und SSL

98 {
7.4 Client-/Server-Beispiel: SMTP mit SARTTLS 401
99 char buf[256], res[256], *cmd, *arg, *tmp;
100 int tls = 0;
101
102 send_smtp_response( bio,
103 "220 manhattan.irgendwie -sowieso.dom ESMTP smtpsrv\n" );
104
105 while( BIO_gets( bio, buf, 256 ) > 0 )
106 {
107 if( ( cmd = strtok_r( buf, " \r\n", &tmp ) ) == NULL )
108 continue; /* Leerzeile oder nur Whitespaces? */
109 arg = strtok_r( NULL, " \r\n", &tmp );
110
111 if( strcasecmp( cmd, "EHLO" ) == 0 )
112 {
113 snprintf( res, 256,
114 "250-manhattan.irgendwie -sowieso.dom Hello %s\n"
115 "250-%s\n"
116 "250 HELP\n",
117 arg ? arg : "unknown", /* Nullzeiger abfangen! */
118 tls ? "AUTH PLAIN LOGIN" : "STARTTLS" );
119 send_smtp_response( bio, res );
120 }
121 else if( strcasecmp( cmd, "STARTTLS" ) == 0 )
122 {
123 if( tls )
124 {
125 send_smtp_response( bio,
126 "503 STARTTLS not advertised\n" );
127 }
128 else
129 {
130 send_smtp_response( bio, "220 TLS go ahead\n" );
131
132 /* Socket -BIO-Kette in SSL-BIO-Kette umwandeln */
133 if( ! ( bio = build_ssl_chain( bio ) ) )
134 {
135 syslog( LOG_ERR , "Can’t create SSL BIO.\n" );
136 errors2syslog();
137 break;
138 }
139
140 tls = 1; /* Merker: Wir sprechen SSL/TLS! */
141 }
142 }
143 else if( strcasecmp( cmd, "QUIT" ) == 0 )
144 {
145 send_smtp_response( bio, "221 closing connection\n" );
146 break;