thodg/libgit2/src/transports/smart.c

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• Hash : 8ee10098
  Author :
  Date : 2018-11-06T13:10:30
  

  transport: see if cert/cred callbacks exist before calling them Custom transports may want to ask libgit2 to invoke a configured credential or certificate callback; however they likely do not know if a callback was actually configured. Return a sentinal value (GIT_PASSTHROUGH) if there is no callback configured instead of crashing.

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• src/transports/smart.c

• /*
   * Copyright (C) the libgit2 contributors. All rights reserved.
   *
   * This file is part of libgit2, distributed under the GNU GPL v2 with
   * a Linking Exception. For full terms see the included COPYING file.
   */
  
  #include "smart.h"
  
  #include "git2.h"
  #include "refs.h"
  #include "refspec.h"
  #include "proxy.h"
  
  static int git_smart__recv_cb(gitno_buffer *buf)
  {
  	transport_smart *t = (transport_smart *) buf->cb_data;
  	size_t old_len, bytes_read;
  	int error;
  
  	assert(t->current_stream);
  
  	old_len = buf->offset;
  
  	if ((error = t->current_stream->read(t->current_stream, buf->data + buf->offset, buf->len - buf->offset, &bytes_read)) < 0)
  		return error;
  
  	buf->offset += bytes_read;
  
  	if (t->packetsize_cb && !t->cancelled.val) {
  		error = t->packetsize_cb(bytes_read, t->packetsize_payload);
  		if (error) {
  			git_atomic_set(&t->cancelled, 1);
  			return GIT_EUSER;
  		}
  	}
  
  	return (int)(buf->offset - old_len);
  }
  
  GIT_INLINE(int) git_smart__reset_stream(transport_smart *t, bool close_subtransport)
  {
  	if (t->current_stream) {
  		t->current_stream->free(t->current_stream);
  		t->current_stream = NULL;
  	}
  
  	if (close_subtransport) {
  		git__free(t->url);
  		t->url = NULL;
  
  		if (t->wrapped->close(t->wrapped) < 0)
  			return -1;
  	}
  
  	return 0;
  }
  
  static int git_smart__set_callbacks(
  	git_transport *transport,
  	git_transport_message_cb progress_cb,
  	git_transport_message_cb error_cb,
  	git_transport_certificate_check_cb certificate_check_cb,
  	void *message_cb_payload)
  {
  	transport_smart *t = (transport_smart *)transport;
  
  	t->progress_cb = progress_cb;
  	t->error_cb = error_cb;
  	t->certificate_check_cb = certificate_check_cb;
  	t->message_cb_payload = message_cb_payload;
  
  	return 0;
  }
  
  static int http_header_name_length(const char *http_header)
  {
  	const char *colon = strchr(http_header, ':');
  	if (!colon)
  		return 0;
  	return colon - http_header;
  }
  
  static bool is_malformed_http_header(const char *http_header)
  {
  	const char *c;
  	int name_len;
  
  	/* Disallow \r and \n */
  	c = strchr(http_header, '\r');
  	if (c)
  		return true;
  	c = strchr(http_header, '\n');
  	if (c)
  		return true;
  
  	/* Require a header name followed by : */
  	name_len = http_header_name_length(http_header);
  	if (name_len < 1)
  		return true;
  
  	return false;
  }
  
  static char *forbidden_custom_headers[] = {
  	"User-Agent",
  	"Host",
  	"Accept",
  	"Content-Type",
  	"Transfer-Encoding",
  	"Content-Length",
  };
  
  static bool is_forbidden_custom_header(const char *custom_header)
  {
  	unsigned long i;
  	int name_len = http_header_name_length(custom_header);
  
  	/* Disallow headers that we set */
  	for (i = 0; i < ARRAY_SIZE(forbidden_custom_headers); i++)
  		if (strncmp(forbidden_custom_headers[i], custom_header, name_len) == 0)
  			return true;
  
  	return false;
  }
  
  static int git_smart__set_custom_headers(
  	git_transport *transport,
  	const git_strarray *custom_headers)
  {
  	transport_smart *t = (transport_smart *)transport;
  	size_t i;
  
  	if (t->custom_headers.count)
  		git_strarray_free(&t->custom_headers);
  
  	if (!custom_headers)
  		return 0;
  
  	for (i = 0; i < custom_headers->count; i++) {
  		if (is_malformed_http_header(custom_headers->strings[i])) {
  			giterr_set(GITERR_INVALID, "custom HTTP header '%s' is malformed", custom_headers->strings[i]);
  			return -1;
  		}
  		if (is_forbidden_custom_header(custom_headers->strings[i])) {
  			giterr_set(GITERR_INVALID, "custom HTTP header '%s' is already set by libgit2", custom_headers->strings[i]);
  			return -1;
  		}
  	}
  
  	return git_strarray_copy(&t->custom_headers, custom_headers);
  }
  
  int git_smart__update_heads(transport_smart *t, git_vector *symrefs)
  {
  	size_t i;
  	git_pkt *pkt;
  
  	git_vector_clear(&t->heads);
  	git_vector_foreach(&t->refs, i, pkt) {
  		git_pkt_ref *ref = (git_pkt_ref *) pkt;
  		if (pkt->type != GIT_PKT_REF)
  			continue;
  
  		if (symrefs) {
  			git_refspec *spec;
  			git_buf buf = GIT_BUF_INIT;
  			size_t j;
  			int error = 0;
  
  			git_vector_foreach(symrefs, j, spec) {
  				git_buf_clear(&buf);
  				if (git_refspec_src_matches(spec, ref->head.name) &&
  				    !(error = git_refspec_transform(&buf, spec, ref->head.name))) {
  					git__free(ref->head.symref_target);
  					ref->head.symref_target = git_buf_detach(&buf);
  				}
  			}
  
  			git_buf_dispose(&buf);
  
  			if (error < 0)
  				return error;
  		}
  
  		if (git_vector_insert(&t->heads, &ref->head) < 0)
  			return -1;
  	}
  
  	return 0;
  }
  
  static void free_symrefs(git_vector *symrefs)
  {
  	git_refspec *spec;
  	size_t i;
  
  	git_vector_foreach(symrefs, i, spec) {
  		git_refspec__dispose(spec);
  		git__free(spec);
  	}
  
  	git_vector_free(symrefs);
  }
  
  static int git_smart__connect(
  	git_transport *transport,
  	const char *url,
  	git_cred_acquire_cb cred_acquire_cb,
  	void *cred_acquire_payload,
  	const git_proxy_options *proxy,
  	int direction,
  	int flags)
  {
  	transport_smart *t = (transport_smart *)transport;
  	git_smart_subtransport_stream *stream;
  	int error;
  	git_pkt *pkt;
  	git_pkt_ref *first;
  	git_vector symrefs;
  	git_smart_service_t service;
  
  	if (git_smart__reset_stream(t, true) < 0)
  		return -1;
  
  	t->url = git__strdup(url);
  	GITERR_CHECK_ALLOC(t->url);
  
  	if (git_proxy_options_dup(&t->proxy, proxy) < 0)
  		return -1;
  
  	t->direction = direction;
  	t->flags = flags;
  	t->cred_acquire_cb = cred_acquire_cb;
  	t->cred_acquire_payload = cred_acquire_payload;
  
  	if (GIT_DIRECTION_FETCH == t->direction)
  		service = GIT_SERVICE_UPLOADPACK_LS;
  	else if (GIT_DIRECTION_PUSH == t->direction)
  		service = GIT_SERVICE_RECEIVEPACK_LS;
  	else {
  		giterr_set(GITERR_NET, "invalid direction");
  		return -1;
  	}
  
  	if ((error = t->wrapped->action(&stream, t->wrapped, t->url, service)) < 0)
  		return error;
  
  	/* Save off the current stream (i.e. socket) that we are working with */
  	t->current_stream = stream;
  
  	gitno_buffer_setup_callback(&t->buffer, t->buffer_data, sizeof(t->buffer_data), git_smart__recv_cb, t);
  
  	/* 2 flushes for RPC; 1 for stateful */
  	if ((error = git_smart__store_refs(t, t->rpc ? 2 : 1)) < 0)
  		return error;
  
  	/* Strip the comment packet for RPC */
  	if (t->rpc) {
  		pkt = (git_pkt *)git_vector_get(&t->refs, 0);
  
  		if (!pkt || GIT_PKT_COMMENT != pkt->type) {
  			giterr_set(GITERR_NET, "invalid response");
  			return -1;
  		} else {
  			/* Remove the comment pkt from the list */
  			git_vector_remove(&t->refs, 0);
  			git__free(pkt);
  		}
  	}
  
  	/* We now have loaded the refs. */
  	t->have_refs = 1;
  
  	pkt = (git_pkt *)git_vector_get(&t->refs, 0);
  	if (pkt && GIT_PKT_REF != pkt->type) {
  		giterr_set(GITERR_NET, "invalid response");
  		return -1;
  	}
  	first = (git_pkt_ref *)pkt;
  
  	if ((error = git_vector_init(&symrefs, 1, NULL)) < 0)
  		return error;
  
  	/* Detect capabilities */
  	if ((error = git_smart__detect_caps(first, &t->caps, &symrefs)) == 0) {
  		/* If the only ref in the list is capabilities^{} with OID_ZERO, remove it */
  		if (1 == t->refs.length && !strcmp(first->head.name, "capabilities^{}") &&
  			git_oid_iszero(&first->head.oid)) {
  			git_vector_clear(&t->refs);
  			git_pkt_free((git_pkt *)first);
  		}
  
  		/* Keep a list of heads for _ls */
  		git_smart__update_heads(t, &symrefs);
  	} else if (error == GIT_ENOTFOUND) {
  		/* There was no ref packet received, or the cap list was empty */
  		error = 0;
  	} else {
  		giterr_set(GITERR_NET, "invalid response");
  		goto cleanup;
  	}
  
  	if (t->rpc && (error = git_smart__reset_stream(t, false)) < 0)
  		goto cleanup;
  
  	/* We're now logically connected. */
  	t->connected = 1;
  
  cleanup:
  	free_symrefs(&symrefs);
  
  	return error;
  }
  
  static int git_smart__ls(const git_remote_head ***out, size_t *size, git_transport *transport)
  {
  	transport_smart *t = (transport_smart *)transport;
  
  	if (!t->have_refs) {
  		giterr_set(GITERR_NET, "the transport has not yet loaded the refs");
  		return -1;
  	}
  
  	*out = (const git_remote_head **) t->heads.contents;
  	*size = t->heads.length;
  
  	return 0;
  }
  
  int git_smart__negotiation_step(git_transport *transport, void *data, size_t len)
  {
  	transport_smart *t = (transport_smart *)transport;
  	git_smart_subtransport_stream *stream;
  	int error;
  
  	if (t->rpc && git_smart__reset_stream(t, false) < 0)
  		return -1;
  
  	if (GIT_DIRECTION_FETCH != t->direction) {
  		giterr_set(GITERR_NET, "this operation is only valid for fetch");
  		return -1;
  	}
  
  	if ((error = t->wrapped->action(&stream, t->wrapped, t->url, GIT_SERVICE_UPLOADPACK)) < 0)
  		return error;
  
  	/* If this is a stateful implementation, the stream we get back should be the same */
  	assert(t->rpc || t->current_stream == stream);
  
  	/* Save off the current stream (i.e. socket) that we are working with */
  	t->current_stream = stream;
  
  	if ((error = stream->write(stream, (const char *)data, len)) < 0)
  		return error;
  
  	gitno_buffer_setup_callback(&t->buffer, t->buffer_data, sizeof(t->buffer_data), git_smart__recv_cb, t);
  
  	return 0;
  }
  
  int git_smart__get_push_stream(transport_smart *t, git_smart_subtransport_stream **stream)
  {
  	int error;
  
  	if (t->rpc && git_smart__reset_stream(t, false) < 0)
  		return -1;
  
  	if (GIT_DIRECTION_PUSH != t->direction) {
  		giterr_set(GITERR_NET, "this operation is only valid for push");
  		return -1;
  	}
  
  	if ((error = t->wrapped->action(stream, t->wrapped, t->url, GIT_SERVICE_RECEIVEPACK)) < 0)
  		return error;
  
  	/* If this is a stateful implementation, the stream we get back should be the same */
  	assert(t->rpc || t->current_stream == *stream);
  
  	/* Save off the current stream (i.e. socket) that we are working with */
  	t->current_stream = *stream;
  
  	gitno_buffer_setup_callback(&t->buffer, t->buffer_data, sizeof(t->buffer_data), git_smart__recv_cb, t);
  
  	return 0;
  }
  
  static void git_smart__cancel(git_transport *transport)
  {
  	transport_smart *t = (transport_smart *)transport;
  
  	git_atomic_set(&t->cancelled, 1);
  }
  
  static int git_smart__is_connected(git_transport *transport)
  {
  	transport_smart *t = (transport_smart *)transport;
  
  	return t->connected;
  }
  
  static int git_smart__read_flags(git_transport *transport, int *flags)
  {
  	transport_smart *t = (transport_smart *)transport;
  
  	*flags = t->flags;
  
  	return 0;
  }
  
  static int git_smart__close(git_transport *transport)
  {
  	transport_smart *t = (transport_smart *)transport;
  	git_vector *common = &t->common;
  	unsigned int i;
  	git_pkt *p;
  	int ret;
  	git_smart_subtransport_stream *stream;
  	const char flush[] = "0000";
  
  	/*
  	 * If we're still connected at this point and not using RPC,
  	 * we should say goodbye by sending a flush, or git-daemon
  	 * will complain that we disconnected unexpectedly.
  	 */
  	if (t->connected && !t->rpc &&
  	    !t->wrapped->action(&stream, t->wrapped, t->url, GIT_SERVICE_UPLOADPACK)) {
  		t->current_stream->write(t->current_stream, flush, 4);
  	}
  
  	ret = git_smart__reset_stream(t, true);
  
  	git_vector_foreach(common, i, p)
  		git_pkt_free(p);
  
  	git_vector_free(common);
  
  	if (t->url) {
  		git__free(t->url);
  		t->url = NULL;
  	}
  
  	t->connected = 0;
  
  	return ret;
  }
  
  static void git_smart__free(git_transport *transport)
  {
  	transport_smart *t = (transport_smart *)transport;
  	git_vector *refs = &t->refs;
  	unsigned int i;
  	git_pkt *p;
  
  	/* Make sure that the current stream is closed, if we have one. */
  	git_smart__close(transport);
  
  	/* Free the subtransport */
  	t->wrapped->free(t->wrapped);
  
  	git_vector_free(&t->heads);
  	git_vector_foreach(refs, i, p)
  		git_pkt_free(p);
  
  	git_vector_free(refs);
  	git__free((char *)t->proxy.url);
  
  	git_strarray_free(&t->custom_headers);
  
  	git__free(t);
  }
  
  static int ref_name_cmp(const void *a, const void *b)
  {
  	const git_pkt_ref *ref_a = a, *ref_b = b;
  
  	return strcmp(ref_a->head.name, ref_b->head.name);
  }
  
  int git_transport_smart_certificate_check(git_transport *transport, git_cert *cert, int valid, const char *hostname)
  {
  	transport_smart *t = (transport_smart *)transport;
  
  	assert(transport && cert && hostname);
  
  	if (!t->certificate_check_cb)
  		return GIT_PASSTHROUGH;
  
  	return t->certificate_check_cb(cert, valid, hostname, t->message_cb_payload);
  }
  
  int git_transport_smart_credentials(git_cred **out, git_transport *transport, const char *user, int methods)
  {
  	transport_smart *t = (transport_smart *)transport;
  
  	assert(out && transport);
  
  	if (!t->cred_acquire_cb)
  		return GIT_PASSTHROUGH;
  
  	return t->cred_acquire_cb(out, t->url, user, methods, t->cred_acquire_payload);
  }
  
  int git_transport_smart_proxy_options(git_proxy_options *out, git_transport *transport)
  {
  	transport_smart *t = (transport_smart *) transport;
  	return git_proxy_options_dup(out, &t->proxy);
  }
  
  int git_transport_smart(git_transport **out, git_remote *owner, void *param)
  {
  	transport_smart *t;
  	git_smart_subtransport_definition *definition = (git_smart_subtransport_definition *)param;
  
  	if (!param)
  		return -1;
  
  	t = git__calloc(1, sizeof(transport_smart));
  	GITERR_CHECK_ALLOC(t);
  
  	t->parent.version = GIT_TRANSPORT_VERSION;
  	t->parent.set_callbacks = git_smart__set_callbacks;
  	t->parent.set_custom_headers = git_smart__set_custom_headers;
  	t->parent.connect = git_smart__connect;
  	t->parent.close = git_smart__close;
  	t->parent.free = git_smart__free;
  	t->parent.negotiate_fetch = git_smart__negotiate_fetch;
  	t->parent.download_pack = git_smart__download_pack;
  	t->parent.push = git_smart__push;
  	t->parent.ls = git_smart__ls;
  	t->parent.is_connected = git_smart__is_connected;
  	t->parent.read_flags = git_smart__read_flags;
  	t->parent.cancel = git_smart__cancel;
  
  	t->owner = owner;
  	t->rpc = definition->rpc;
  
  	if (git_vector_init(&t->refs, 16, ref_name_cmp) < 0) {
  		git__free(t);
  		return -1;
  	}
  
  	if (git_vector_init(&t->heads, 16, ref_name_cmp) < 0) {
  		git__free(t);
  		return -1;
  	}
  
  	if (definition->callback(&t->wrapped, &t->parent, definition->param) < 0) {
  		git__free(t);
  		return -1;
  	}
  
  	*out = (git_transport *) t;
  	return 0;
  }
  

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