SSH compression by linking with zlib.dll if present (compression

quietly becomes unavailable if zlib.dll not found). Thanks to Joris
van Rantwijk (again).

[originally from svn r511]

putty.h

@@ -134,6 +134,7 @@ typedef struct {
     int nopty;
     enum { CIPHER_3DES, CIPHER_BLOWFISH, CIPHER_DES } cipher;
     int try_tis_auth;
+    int ssh_compression;
     /* Telnet options */
     char termtype[32];
     char termspeed[32];
@@ -194,6 +195,14 @@ GLOBAL int default_port;
 
 struct RSAKey;			       /* be a little careful of scope */
 
+/*
+ * Needed for PuTTY Secure Copy
+ */
+#define SCP_FLAG	1
+#define SCP_VERBOSE	2
+#define IS_SCP ((scp_flags & SCP_FLAG) != 0)
+GLOBAL int scp_flags;
+
 /*
  * Exports from window.c.
  */

scp.h

@@ -3,12 +3,7 @@
  *  Joris van Rantwijk, Aug 1999, Jun 2000.
  */
 
-#define SCP_FLAG	1
-#define SCP_VERBOSE	2
-#define IS_SCP ((scp_flags & SCP_FLAG) != 0)
-
 /* Exported from ssh.c */
-extern int scp_flags;
 extern void (*ssh_get_password)(const char *prompt, char *str, int maxlen);
 char * ssh_scp_init(char *host, int port, char *cmd, char **realhost);
 int ssh_scp_recv(unsigned char *buf, int len);

ssh.c

@@ -15,10 +15,6 @@
 #define TRUE 1
 #endif
 
-#define logevent(s) { logevent(s); \
-                      if (IS_SCP && (scp_flags & SCP_VERBOSE) != 0) \
-                      fprintf(stderr, "%s\n", s); }
-
 #define SSH_MSG_DISCONNECT	1
 #define SSH_SMSG_PUBLIC_KEY	2
 #define SSH_CMSG_SESSION_KEY	3
@@ -38,11 +34,13 @@
 #define SSH_CMSG_EXIT_CONFIRMATION	33
 #define SSH_MSG_IGNORE		32
 #define SSH_MSG_DEBUG		36
+#define SSH_CMSG_REQUEST_COMPRESSION	37
 #define SSH_CMSG_AUTH_TIS	39
 #define SSH_SMSG_AUTH_TIS_CHALLENGE	40
 #define SSH_CMSG_AUTH_TIS_RESPONSE	41
 
 #define SSH_AUTH_TIS		5
+#define COMPRESSION_LEVEL	5
 
 #define GET_32BIT(cp) \
     (((unsigned long)(unsigned char)(cp)[0] << 24) | \
@@ -80,7 +78,7 @@ static SOCKET s = INVALID_SOCKET;
 
 static unsigned char session_key[32];
 static struct ssh_cipher *cipher = NULL;
-int scp_flags = 0;
+static int use_compression = 0;
 void (*ssh_get_password)(const char *prompt, char *str, int maxlen) = NULL;
 
 static char *savedhost;
@@ -155,6 +153,24 @@ static void ssh_protocol(unsigned char *in, int inlen, int ispkt);
 static void ssh_size(void);
 
 
+static void pktalloc(struct Packet *pkt, long newlen)
+{
+    if (pkt->maxlen < newlen) {
+	pkt->maxlen = newlen;
+#ifdef MSCRYPTOAPI
+	/* Allocate enough buffer space for extra block
+	 * for MS CryptEncrypt() */
+	pkt->data = (pkt->data == NULL ? malloc(newlen+8) :
+	              realloc(pkt->data, newlen+8));
+#else
+	pkt->data = (pkt->data == NULL ? malloc(newlen) :
+	              realloc(pkt->data, newlen));
+#endif
+	if (!pkt->data)
+	    fatalbox("Out of memory");
+    }
+}
+
 /*
  * Collect incoming data in the incoming packet buffer.
  * Decihper and verify the packet when it is completely read.
@@ -192,22 +208,9 @@ next_packet:
 
     pad = 8 - (len % 8);
     biglen = len + pad;
-    pktin.length = len - 5;
 
-    if (pktin.maxlen < biglen) {
+    if (pktin.maxlen < biglen)
-	pktin.maxlen = biglen;
+	pktalloc(&pktin, biglen);
-#ifdef MSCRYPTOAPI
-	/* Allocate enough buffer space for extra block
-	 * for MS CryptEncrypt() */
-	pktin.data = (pktin.data == NULL ? malloc(biglen+8) :
-	              realloc(pktin.data, biglen+8));
-#else
-	pktin.data = (pktin.data == NULL ? malloc(biglen) :
-	              realloc(pktin.data, biglen));
-#endif
-	if (!pktin.data)
-	    fatalbox("Out of memory");
-    }
 
     to_read = biglen;
     p = pktin.data;
@@ -228,15 +231,23 @@ next_packet:
     if (cipher)
 	cipher->decrypt(pktin.data, biglen);
 
-    pktin.type = pktin.data[pad];
-    pktin.body = pktin.data + pad + 1;
-
     realcrc = crc32(pktin.data, biglen-4);
     gotcrc = GET_32BIT(pktin.data+biglen-4);
     if (gotcrc != realcrc) {
 	fatalbox("Incorrect CRC received on packet");
     }
 
+    if (use_compression) {
+	ssh_decompress(pktin.data + pad, len - 4, &p, &len);
+	pktin.length = len - 1;
+	pktin.type = p[0];
+	pktin.body = p + 1;
+    } else {
+	pktin.length = len - 5;
+	pktin.type = pktin.data[pad];
+	pktin.body = pktin.data + pad + 1;
+    }
+
     if (pktin.type == SSH_SMSG_STDOUT_DATA ||
         pktin.type == SSH_SMSG_STDERR_DATA ||
         pktin.type == SSH_MSG_DEBUG ||
@@ -281,20 +292,8 @@ static void s_wrpkt_start(int type, int len) {
     biglen = len + pad;
 
     pktout.length = len-5;
-    if (pktout.maxlen < biglen) {
+    if (pktout.maxlen < biglen + 4)
-	pktout.maxlen = biglen;
+	pktalloc(&pktout, biglen + 4);
-#ifdef MSCRYPTOAPI
-	/* Allocate enough buffer space for extra block
-	 * for MS CryptEncrypt() */
-	pktout.data = (pktout.data == NULL ? malloc(biglen+12) :
-		       realloc(pktout.data, biglen+12));
-#else
-	pktout.data = (pktout.data == NULL ? malloc(biglen+4) :
-		       realloc(pktout.data, biglen+4));
-#endif
-	if (!pktout.data)
-	    fatalbox("Out of memory");
-    }
 
     pktout.type = type;
     pktout.body = pktout.data+4+pad+1;
@@ -307,8 +306,21 @@ static void s_wrpkt(void) {
     len = pktout.length + 5;	       /* type and CRC */
     pad = 8 - (len%8);
     biglen = len + pad;
-
     pktout.body[-1] = pktout.type;
+
+    if (use_compression) {
+	unsigned char *p;
+	unsigned int n;
+	pktout.body = NULL;
+	ssh_compress(pktout.data + 4 + pad, pktout.length + 1, &p, &n);
+	len = n + 4;
+	pad = 8 - (len%8);
+	biglen = len + pad;
+	if (pktout.maxlen < biglen + 4)
+	    pktalloc(&pktout, biglen + 4);
+	memcpy(pktout.data + 4 + pad, p, n);
+    }
+
     for (i=0; i<pad; i++)
 	pktout.data[i+4] = random_byte();
     crc = crc32(pktout.data+4, biglen-4);
@@ -853,6 +865,21 @@ static int do_ssh_login(unsigned char *in, int inlen, int ispkt)
 
     logevent("Authentication successful");
 
+    if (cfg.ssh_compression &&
+        ssh_compression_init(COMPRESSION_LEVEL)) {
+	send_packet(SSH_CMSG_REQUEST_COMPRESSION,
+	            PKT_INT, COMPRESSION_LEVEL, PKT_END);
+	crWaitUntil(ispkt);
+	if (pktin.type == SSH_SMSG_SUCCESS) {
+	    use_compression = 1;
+	    logevent("Enabled SSH packet compression");
+	} else if (pktin.type == SSH_SMSG_FAILURE) {
+	    logevent("Server does not support packet compression");
+	} else {
+	    fatalbox("Strange packet received, type %d", pktin.type);
+	}
+    }
+
     crFinish(1);
 }
 

ssh.h

@@ -62,3 +62,10 @@ int random_byte(void);
 void random_add_noise(void *noise, int length);
 
 void logevent (char *);
+
+int ssh_compression_init(int);
+void ssh_compress(unsigned char *src, unsigned int srclen,
+                  unsigned char **dest, unsigned int *destlen);
+void ssh_decompress(unsigned char *src, unsigned int srclen,
+                    unsigned char **dest, unsigned int *destlen);
+

win_res.h

@@ -110,6 +110,7 @@
 #define IDC3_CIPHERBLOWF 1021
 #define IDC3_CIPHERDES  1022
 #define IDC3_AUTHTIS    1023
+#define IDC3_COMPRESS	1024
 
 #define IDC4_MBSTATIC   1001
 #define IDC4_MBWINDOWS  1002

win_res.rc

@@ -198,6 +198,7 @@ BEGIN
     AUTORADIOBUTTON "&Blowfish", IDC3_CIPHERBLOWF, 84, 50, 40, 10
     AUTORADIOBUTTON "&DES", IDC3_CIPHERDES, 127, 50, 30, 10
     AUTOCHECKBOX "Attempt TIS authentication", IDC3_AUTHTIS, 3, 60, 162, 10
+    AUTOCHECKBOX "Enable packet compression", IDC3_COMPRESS, 3, 70, 162, 10
 END
 
 IDD_PANEL4 DIALOG DISCARDABLE 6, 30, 168, 163

windlg.c

@@ -152,6 +152,7 @@ static void save_settings (char *section, int do_host) {
     wpps (sesskey, "Cipher", cfg.cipher == CIPHER_BLOWFISH ? "blowfish" :
                              cfg.cipher == CIPHER_DES ? "des" : "3des");
     wppi (sesskey, "AuthTIS", cfg.try_tis_auth);
+    wppi (sesskey, "SSHCompression", cfg.ssh_compression);
     wppi (sesskey, "RFCEnviron", cfg.rfc_environ);
     wppi (sesskey, "BackspaceIsDelete", cfg.bksp_is_delete);
     wppi (sesskey, "RXVTHomeEnd", cfg.rxvt_homeend);
@@ -288,6 +289,7 @@ static void load_settings (char *section, int do_host) {
 	    cfg.cipher = CIPHER_3DES;
     }
     gppi (sesskey, "AuthTIS", 0, &cfg.try_tis_auth);
+    gppi (sesskey, "SSHCompression", 0, &cfg.ssh_compression);
     gppi (sesskey, "RFCEnviron", 0, &cfg.rfc_environ);
     gppi (sesskey, "BackspaceIsDelete", 1, &cfg.bksp_is_delete);
     gppi (sesskey, "RXVTHomeEnd", 0, &cfg.rxvt_homeend);
@@ -956,6 +958,7 @@ static int CALLBACK SshProc (HWND hwnd, UINT msg,
 
 			  IDC3_CIPHER3DES);
 	CheckDlgButton (hwnd, IDC3_AUTHTIS, cfg.try_tis_auth);
+	CheckDlgButton (hwnd, IDC3_COMPRESS, cfg.ssh_compression);
 	break;
       case WM_COMMAND:
 	switch (LOWORD(wParam)) {
@@ -992,6 +995,11 @@ static int CALLBACK SshProc (HWND hwnd, UINT msg,
 		HIWORD(wParam) == BN_DOUBLECLICKED)
 		cfg.try_tis_auth = IsDlgButtonChecked (hwnd, IDC3_AUTHTIS);
 	    break;
+	  case IDC3_COMPRESS:
+	    if (HIWORD(wParam) == BN_CLICKED ||
+	        HIWORD(wParam) == BN_DOUBLECLICKED)
+		cfg.ssh_compression = IsDlgButtonChecked (hwnd, IDC3_COMPRESS);
+	    break;
 	}
 	break;
     }
@@ -1423,6 +1431,8 @@ void do_defaults (char *session) {
 }
 
 void logevent (char *string) {
+    if (IS_SCP && (scp_flags & SCP_VERBOSE) != 0)
+	fprintf(stderr, "%s\n", string);
     if (nevents >= negsize) {
 	negsize += 64;
 	events = srealloc (events, negsize * sizeof(*events));