1 files changed, 136 insertions, 0 deletions
diff --git a/proxy/socks4.c b/proxy/socks4.c
new file mode 100644
index 00000000..ac85ec05
--- /dev/null
+++ b/proxy/socks4.c
@@ -0,0 +1,136 @@
+/*
+ * SOCKS 4 proxy negotiation.
+ */
+
+#include "putty.h"
+#include "network.h"
+#include "proxy.h"
+#include "socks.h"
+#include "sshcr.h"
+
+typedef struct Socks4ProxyNegotiator {
+    int crLine;
+    ProxyNegotiator pn;
+} Socks4ProxyNegotiator;
+
+static ProxyNegotiator *proxy_socks4_new(const ProxyNegotiatorVT *vt)
+{
+    Socks4ProxyNegotiator *s = snew(Socks4ProxyNegotiator);
+    s->pn.vt = vt;
+    s->crLine = 0;
+    return &s->pn;
+}
+
+static void proxy_socks4_free(ProxyNegotiator *pn)
+{
+    Socks4ProxyNegotiator *s = container_of(pn, Socks4ProxyNegotiator, pn);
+    sfree(s);
+}
+
+static void proxy_socks4_process_queue(ProxyNegotiator *pn)
+{
+    Socks4ProxyNegotiator *s = container_of(pn, Socks4ProxyNegotiator, pn);
+
+    crBegin(s->crLine);
+
+    {
+        char hostname[512];
+        bool write_hostname = false;
+
+        /*
+         * SOCKS 4 request packet:
+         *
+         *   byte     version
+         *   byte     command
+         *   uint16   destination port number
+         *   uint32   destination IPv4 address (or something in the
+         *            SOCKS4A_NAME_FOLLOWS range)
+         *   asciz    username
+         *   asciz    destination hostname (if we sent SOCKS4A_NAME_FOLLOWS_*)
+         */
+
+        put_byte(pn->output, SOCKS4_REQUEST_VERSION);
+        put_byte(pn->output, SOCKS_CMD_CONNECT);
+        put_uint16(pn->output, pn->ps->remote_port);
+
+        switch (sk_addrtype(pn->ps->remote_addr)) {
+          case ADDRTYPE_IPV4: {
+            char addr[4];
+            sk_addrcopy(pn->ps->remote_addr, addr);
+            put_data(pn->output, addr, 4);
+            break;
+          }
+          case ADDRTYPE_NAME:
+            put_uint32(pn->output, SOCKS4A_NAME_FOLLOWS_BASE);
+            sk_getaddr(pn->ps->remote_addr, hostname, lenof(hostname));
+            write_hostname = true;
+            break;
+          case ADDRTYPE_IPV6:
+            pn->error = dupstr("SOCKS version 4 does not support IPv6");
+            crStopV;
+        }
+
+        put_asciz(pn->output, conf_get_str(pn->ps->conf, CONF_proxy_username));
+
+        if (write_hostname)
+            put_asciz(pn->output, hostname);
+    }
+
+    crReturnV;
+
+    {
+        unsigned char data[8];
+        crMaybeWaitUntilV(bufchain_try_fetch_consume(pn->input, data, 8));
+
+        /*
+         * SOCKS 4 response packet:
+         *
+         *   byte     version
+         *   byte     status
+         *   uint16   port number
+         *   uint32   IPv4 address
+         *
+         * We don't need to worry about the port and destination address.
+         */
+
+        if (data[0] != SOCKS4_REPLY_VERSION) {
+            pn->error = dupprintf("SOCKS proxy response contained reply "
+                                  "version number %d (expected 0)",
+                                  (int)data[0]);
+            crStopV;
+        }
+
+        switch (data[1]) {
+          case SOCKS4_RESP_SUCCESS:
+            pn->done = true;
+            break;
+
+          case SOCKS4_RESP_FAILURE:
+            pn->error = dupstr("SOCKS server reported failure to connect");
+            break;
+
+          case SOCKS4_RESP_WANT_IDENTD:
+            pn->error = dupstr("SOCKS server wanted IDENTD on client");
+            break;
+
+          case SOCKS4_RESP_IDENTD_MISMATCH:
+            pn->error = dupstr("Username and IDENTD on client don't agree");
+            break;
+
+          default:
+            pn->error = dupprintf("SOCKS server sent unrecognised error "
+                                  "code %d", (int)data[1]);
+            break;
+        }
+        crStopV;
+    }
+
+    crFinishV;
+}
+
+const struct ProxyNegotiatorVT socks4_proxy_negotiator_vt = {
+    .new = proxy_socks4_new,
+    .free = proxy_socks4_free,
+    .process_queue = proxy_socks4_process_queue,
+    .type = "SOCKS 4",
+};