1 files changed, 439 insertions, 0 deletions

diff --git a/nsock/src/nsock_proxy.c b/nsock/src/nsock_proxy.c
new file mode 100644
index 0000000..29a1f3d
--- /dev/null
+++ b/nsock/src/nsock_proxy.c
@@ -0,0 +1,439 @@
+/***************************************************************************
+ * nsock_proxy.c -- This contains the functions relating to proxies.       *
+ *                                                                         *
+ ***********************IMPORTANT NSOCK LICENSE TERMS***********************
+ *
+ * The nsock parallel socket event library is (C) 1999-2023 Nmap Software LLC
+ * This library is free software; you may redistribute and/or modify it under
+ * the terms of the GNU General Public License as published by the Free Software
+ * Foundation; Version 2. This guarantees your right to use, modify, and
+ * redistribute this software under certain conditions. If this license is
+ * unacceptable to you, Nmap Software LLC may be willing to sell alternative
+ * licenses (contact sales@nmap.com ).
+ *
+ * As a special exception to the GPL terms, Nmap Software LLC grants permission
+ * to link the code of this program with any version of the OpenSSL library
+ * which is distributed under a license identical to that listed in the included
+ * docs/licenses/OpenSSL.txt file, and distribute linked combinations including
+ * the two. You must obey the GNU GPL in all respects for all of the code used
+ * other than OpenSSL. If you modify this file, you may extend this exception to
+ * your version of the file, but you are not obligated to do so.
+ *
+ * If you received these files with a written license agreement stating terms
+ * other than the (GPL) terms above, then that alternative license agreement
+ * takes precedence over this comment.
+ *
+ * Source is provided to this software because we believe users have a right to
+ * know exactly what a program is going to do before they run it. This also
+ * allows you to audit the software for security holes.
+ *
+ * Source code also allows you to port Nmap to new platforms, fix bugs, and add
+ * new features. You are highly encouraged to send your changes to the
+ * dev@nmap.org mailing list for possible incorporation into the main
+ * distribution. By sending these changes to Fyodor or one of the Insecure.Org
+ * development mailing lists, or checking them into the Nmap source code
+ * repository, it is understood (unless you specify otherwise) that you are
+ * offering the Nmap Project (Nmap Software LLC) the unlimited, non-exclusive
+ * right to reuse, modify, and relicense the code. Nmap will always be available
+ * Open Source, but this is important because the inability to relicense code
+ * has caused devastating problems for other Free Software projects (such as KDE
+ * and NASM). We also occasionally relicense the code to third parties as
+ * discussed above. If you wish to specify special license conditions of your
+ * contributions, just say so when you send them.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE. See the GNU General Public License v2.0 for more
+ * details (http://www.gnu.org/licenses/gpl-2.0.html).
+ *
+ ***************************************************************************/
+
+/* $Id$ */
+
+#include "nsock.h"
+#include "nsock_internal.h"
+#include "nsock_log.h"
+#include <string.h>
+
+#define IN_RANGE(x, min, max) ((x) >= (min) && (x) <= (max))
+
+static struct proxy_node *proxy_node_new(const char *proxystr, const char *end);
+
+/* --- Implemented proxy backends --- */
+extern const struct proxy_spec ProxySpecHttp;
+extern const struct proxy_spec ProxySpecSocks4;
+
+
+static const struct proxy_spec *ProxyBackends[] = {
+  &ProxySpecHttp,
+  &ProxySpecSocks4,
+  NULL
+};
+
+
+/* A proxy chain is a comma-separated list of proxy specification strings:
+ * proto://[user:pass@]host[:port] */
+int nsock_proxychain_new(const char *proxystr, nsock_proxychain *chain, nsock_pool nspool) {
+  struct npool *nsp = (struct npool *)nspool;
+  struct proxy_chain *pxc, **pchain = (struct proxy_chain **)chain;
+
+  *pchain = NULL;
+
+  pxc = (struct proxy_chain *)safe_malloc(sizeof(struct proxy_chain));
+  gh_list_init(&pxc->nodes);
+
+  if (proxystr) {
+    const char *next = proxystr;
+    const char *end = strchr(proxystr, ',');
+    struct proxy_node *proxy;
+
+    while (end != NULL) {
+      proxy = proxy_node_new(next, end);
+      if (!proxy)
+        return -1;
+      gh_list_append(&pxc->nodes, &proxy->nodeq);
+      next = end + 1;
+      end = strchr(next, ',');
+    }
+    proxy = proxy_node_new(next, strchr(next, '\0'));
+    if (!proxy)
+      return -1;
+    gh_list_append(&pxc->nodes, &proxy->nodeq);
+  }
+
+  if (nsp) {
+    if (nsock_pool_set_proxychain(nspool, pxc) < 0) {
+      nsock_proxychain_delete(pxc);
+      return -1;
+    }
+  }
+
+  *pchain = pxc;
+  return 1;
+}
+
+void nsock_proxychain_delete(nsock_proxychain chain) {
+  struct proxy_chain *pchain = (struct proxy_chain *)chain;
+  gh_lnode_t *lnode;
+
+  if (!pchain)
+    return;
+
+  while ((lnode = gh_list_pop(&pchain->nodes)) != NULL) {
+    struct proxy_node *node;
+
+    node = container_of(lnode, struct proxy_node, nodeq);
+    node->spec->ops->node_delete(node);
+  }
+
+  gh_list_free(&pchain->nodes);
+  free(pchain);
+}
+
+int nsock_pool_set_proxychain(nsock_pool nspool, nsock_proxychain chain) {
+  struct npool *nsp = (struct npool *)nspool;
+  assert(nsp != NULL);
+
+  if (nsp && nsp->px_chain) {
+    nsock_log_error("Invalid call. Existing proxychain on this nsock_pool");
+    return -1;
+  }
+
+  if (gh_list_count(&chain->nodes) < 1) {
+    nsock_log_error("Invalid call. No proxies in chain");
+    return -1;
+  }
+
+  nsp->px_chain = (struct proxy_chain *)chain;
+  return 1;
+}
+
+struct proxy_chain_context *proxy_chain_context_new(nsock_pool nspool) {
+  struct npool *nsp = (struct npool *)nspool;
+  struct proxy_chain_context *ctx;
+
+  ctx = (struct proxy_chain_context *)safe_malloc(sizeof(struct proxy_chain_context));
+  ctx->px_chain = nsp->px_chain;
+  ctx->px_state = PROXY_STATE_INITIAL;
+  ctx->px_current = container_of(gh_list_first_elem(&nsp->px_chain->nodes),
+                                 struct proxy_node,
+                                 nodeq);
+  return ctx;
+}
+
+void proxy_chain_context_delete(struct proxy_chain_context *ctx) {
+  free(ctx);
+}
+
+static void uri_free(struct uri *uri) {
+  free(uri->scheme);
+  free(uri->user);
+  free(uri->pass);
+  free(uri->host);
+  free(uri->path);
+}
+
+static int lowercase(char *s) {
+  char *p;
+
+  for (p = s; *p != '\0'; p++)
+    *p = tolower((int) (unsigned char) *p);
+
+  return p - s;
+}
+
+static int hex_digit_value(char digit) {
+  static const char DIGITS[] = "0123456789abcdef";
+  const char *p;
+
+  if ((unsigned char)digit == '\0')
+    return -1;
+
+  p = strchr(DIGITS, tolower((int)(unsigned char)digit));
+  if (p == NULL)
+    return -1;
+
+  return p - DIGITS;
+}
+
+static int percent_decode(char *s) {
+  char *p, *q;
+
+  /* Skip to the first '%'. If there are no percent escapes, this lets us
+   * return without doing any copying. */
+  q = s;
+  while (*q != '\0' && *q != '%')
+    q++;
+
+  p = q;
+  while (*q != '\0') {
+    if (*q == '%') {
+      int c, d;
+
+      q++;
+      c = hex_digit_value(*q);
+      if (c == -1)
+        return -1;
+      q++;
+      d = hex_digit_value(*q);
+      if (d == -1)
+        return -1;
+
+      *p++ = c * 16 + d;
+      q++;
+      } else {
+        *p++ = *q++;
+      }
+  }
+  *p = '\0';
+
+  return p - s;
+}
+
+static int uri_parse_authority(const char *authority, const char *end, struct uri *uri) {
+  const char *portsep;
+  const char *host_start, *host_end;
+  const char *tail;
+
+  /* We do not support "user:pass@" userinfo. The proxy has no use for it. */
+  if (strchr_p(authority, end, '@') != NULL)
+    return -1;
+
+  /* Find the beginning and end of the host. */
+  host_start = authority;
+
+  if (*host_start == '[') {
+    /* IPv6 address in brackets. */
+    host_start++;
+    if (host_start >= end ||
+        NULL == (host_end = strchr_p(host_start, end, ']'))
+       ) {
+      nsock_log_error("Invalid IPv6 address: %s", authority);
+      return -1;
+    }
+
+    portsep = host_end + 1;
+
+  } else {
+    for (portsep = end; portsep > host_start && *portsep != ':'; portsep--);
+
+    if (portsep == host_start)
+      portsep = end;
+    host_end = portsep;
+  }
+
+  /* Get the port number. */
+  if (portsep + 1 < end && *portsep == ':') {
+    long n;
+
+    errno = 0;
+    n = parse_long(portsep + 1, &tail);
+    if (errno || tail != end || !IN_RANGE(n, 1, 65535)) {
+      nsock_log_error("Invalid port number (%ld), errno = %d", n, errno);
+      return -1;
+    }
+    uri->port = n;
+  } else {
+    uri->port = -1;
+  }
+
+  /* Get the host. */
+  uri->host = mkstr(host_start, host_end);
+  if (percent_decode(uri->host) < 0) {
+    nsock_log_error("Invalid URL encoding in host: %s", uri->host);
+    free(uri->host);
+    uri->host = NULL;
+    return -1;
+  }
+
+  return 1;
+}
+
+static int parse_uri(const char *proxystr, const char *end, struct uri *uri) {
+  const char *p, *q;
+
+  /* Scheme, section 3.1. */
+  p = proxystr;
+  if (!isalpha(*p))
+    goto fail;
+
+  q = p;
+  while (isalpha(*q) || isdigit(*q) || *q == '+' || *q == '-' || *q == '.') {
+    q++;
+    if (q >= end)
+      goto fail;
+  }
+
+  if (*q != ':')
+      goto fail;
+
+  uri->scheme = mkstr(p, q);
+
+  /* "An implementation should accept uppercase letters as equivalent to
+   * lowercase in scheme names (e.g., allow "HTTP" as well as "http") for the
+   * sake of robustness..." */
+  lowercase(uri->scheme);
+
+  /* Authority, section 3.2. */
+  p = q + 1;
+  if (p >= end)
+    goto fail;
+  if (p + 1 < end && *p == '/' && *(p + 1) == '/') {
+
+    p += 2;
+    q = p;
+    while (q < end && !(*q == '/' || *q == '?' || *q == '#' || *q == '\0'))
+      q++;
+
+    if (uri_parse_authority(p, q, uri) < 0) {
+      goto fail;
+    }
+
+    p = q;
+  }
+
+  /* Path, section 3.3. We include the query and fragment in the path. The
+   * path is also not percent-decoded because we just pass it on to the origin
+   * server. */
+
+  uri->path = mkstr(p, end);
+
+  return 1;
+
+fail:
+  uri_free(uri);
+  return -1;
+}
+
+static struct proxy_node *proxy_node_new(const char *proxystr, const char *end) {
+  int i;
+
+  for (i = 0; ProxyBackends[i] != NULL; i++) {
+    const struct proxy_spec *pspec;
+    size_t prefix_len;
+
+    pspec = ProxyBackends[i];
+    prefix_len = strlen(pspec->prefix);
+    if (end - proxystr > prefix_len && strncasecmp(proxystr, pspec->prefix, prefix_len) == 0) {
+      struct proxy_node *proxy = NULL;
+      struct uri uri;
+
+      memset(&uri, 0x00, sizeof(struct uri));
+
+      if (parse_uri(proxystr, end, &uri) < 0)
+        break;
+
+      if (pspec->ops->node_new(&proxy, &uri) < 0) {
+        nsock_log_error("Cannot initialize proxy node %s", proxystr);
+        uri_free(&uri);
+        break;
+      }
+
+      uri_free(&uri);
+
+      return proxy;
+    }
+  }
+  nsock_log_error("Invalid protocol in proxy specification string: %s", proxystr);
+  return NULL;
+}
+
+void forward_event(nsock_pool nspool, nsock_event nsevent, void *udata) {
+  struct npool *nsp = (struct npool *)nspool;
+  struct nevent *nse = (struct nevent *)nsevent;
+  enum nse_type cached_type;
+  enum nse_status cached_status;
+
+  cached_type = nse->type;
+  cached_status = nse->status;
+
+  nse->type = nse->iod->px_ctx->target_ev_type;
+
+  if (nse->status != NSE_STATUS_SUCCESS)
+    nse->status = NSE_STATUS_PROXYERROR;
+
+  nsock_log_info("Forwarding event upstream: TCP connect %s (IOD #%li) EID %li",
+                 nse_status2str(nse->status), nse->iod->id, nse->id);
+
+  nse->iod->px_ctx->target_handler(nsp, nse, udata);
+
+  nse->type = cached_type;
+  nse->status = cached_status;
+}
+
+void nsock_proxy_ev_dispatch(nsock_pool nspool, nsock_event nsevent, void *udata) {
+  struct nevent *nse = (struct nevent *)nsevent;
+
+  if (nse->status == NSE_STATUS_SUCCESS) {
+    struct proxy_node *current;
+
+    current = nse->iod->px_ctx->px_current;
+    assert(current);
+    current->spec->ops->handler(nspool, nsevent, udata);
+  } else {
+    forward_event(nspool, nsevent, udata);
+  }
+}
+
+int proxy_resolve(const char *host, struct sockaddr *addr, size_t *addrlen, int ai_family) {
+  struct addrinfo hints;
+  struct addrinfo *res;
+  int rc;
+
+  memset(&hints, 0, sizeof(hints));
+  hints.ai_family = ai_family;
+  /* All proxy types are TCP-only at the moment */
+  hints.ai_socktype = SOCK_STREAM;
+
+  rc = getaddrinfo(host, NULL, &hints, &res);
+  if (rc) {
+    nsock_log_info("getaddrinfo error: %s", gai_strerror(rc));
+    return -abs(rc);
+  }
+
+  *addr = *res->ai_addr;
+  *addrlen = res->ai_addrlen;
+  freeaddrinfo(res);
+  return 1;
+}
+