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// Copyright (c) 2016, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
#include "vm/uri.h"
#include "vm/zone.h"
namespace dart {
static bool IsUnreservedChar(intptr_t value) {
return ((value >= 'a' && value <= 'z') || (value >= 'A' && value <= 'Z') ||
(value >= '0' && value <= '9') || value == '-' || value == '.' ||
value == '_' || value == '~');
}
static bool IsDelimiter(intptr_t value) {
switch (value) {
case ':':
case '/':
case '?':
case '#':
case '[':
case ']':
case '@':
case '!':
case '$':
case '&':
case '\'':
case '(':
case ')':
case '*':
case '+':
case ',':
case ';':
case '=':
return true;
default:
return false;
}
}
static bool IsHexDigit(char value) {
return ((value >= '0' && value <= '9') || (value >= 'A' && value <= 'F') ||
(value >= 'a' && value <= 'f'));
}
static int HexValue(char digit) {
if ((digit >= '0' && digit <= '9')) {
return digit - '0';
}
if ((digit >= 'A' && digit <= 'F')) {
return digit - 'A' + 10;
}
if ((digit >= 'a' && digit <= 'f')) {
return digit - 'a' + 10;
}
UNREACHABLE();
return 0;
}
static int GetEscapedValue(const char* str, intptr_t pos, intptr_t len) {
if (pos + 2 >= len) {
// Not enough room for a valid escape sequence.
return -1;
}
if (str[pos] != '%') {
// Escape sequences start with '%'.
return -1;
}
char digit1 = str[pos + 1];
char digit2 = str[pos + 2];
if (!IsHexDigit(digit1) || !IsHexDigit(digit2)) {
// Invalid escape sequence. Ignore it.
return -1;
}
return HexValue(digit1) * 16 + HexValue(digit2);
}
static char* NormalizeEscapes(const char* str, intptr_t len) {
// Allocate the buffer.
Zone* zone = Thread::Current()->zone();
// We multiply len by three because a percent-escape sequence is
// three characters long (e.g. ' ' -> '%20). +1 for '\0'. We could
// take two passes through the string and avoid the excess
// allocation, but it's zone-memory so it doesn't seem necessary.
char* buffer = zone->Alloc<char>(len * 3 + 1);
// Copy the string, normalizing as we go.
intptr_t buffer_pos = 0;
intptr_t pos = 0;
while (pos < len) {
int escaped_value = GetEscapedValue(str, pos, len);
if (escaped_value >= 0) {
// If one of the special "unreserved" characters has been
// escaped, revert the escaping. Otherwise preserve the
// escaping.
if (IsUnreservedChar(escaped_value)) {
buffer[buffer_pos] = escaped_value;
buffer_pos++;
} else {
Utils::SNPrint(buffer + buffer_pos, 4, "%%%02X", escaped_value);
buffer_pos += 3;
}
pos += 3;
} else {
char c = str[pos];
// If a delimiter or unreserved character is currently not
// escaped, preserve that. If there is a busted %-sequence in
// the input, preserve that too.
if (c == '%' || IsDelimiter(c) || IsUnreservedChar(c)) {
buffer[buffer_pos] = c;
buffer_pos++;
} else {
// Escape funky characters.
Utils::SNPrint(buffer + buffer_pos, 4, "%%%02X", c);
buffer_pos += 3;
}
pos++;
}
}
buffer[buffer_pos] = '\0';
return buffer;
}
// Lower-case a string in place.
static void StringLower(char* str) {
const intptr_t len = strlen(str);
intptr_t i = 0;
while (i < len) {
int escaped_value = GetEscapedValue(str, i, len);
if (escaped_value >= 0) {
// Don't lowercase escape sequences.
i += 3;
} else {
// I don't use tolower() because I don't want the locale
// transforming any non-acii characters.
char c = str[i];
if (c >= 'A' && c <= 'Z') {
str[i] = c + ('a' - 'A');
}
i++;
}
}
}
static void ClearParsedUri(ParsedUri* parsed_uri) {
parsed_uri->scheme = NULL;
parsed_uri->userinfo = NULL;
parsed_uri->host = NULL;
parsed_uri->port = NULL;
parsed_uri->path = NULL;
parsed_uri->query = NULL;
parsed_uri->fragment = NULL;
}
static intptr_t ParseAuthority(const char* authority, ParsedUri* parsed_uri) {
Zone* zone = Thread::Current()->zone();
const char* current = authority;
intptr_t len = 0;
size_t userinfo_len = strcspn(current, "@/");
if (current[userinfo_len] == '@') {
// The '@' character follows the optional userinfo string.
parsed_uri->userinfo = NormalizeEscapes(current, userinfo_len);
current += userinfo_len + 1;
len += userinfo_len + 1;
} else {
parsed_uri->userinfo = NULL;
}
size_t host_len = strcspn(current, ":/");
char* host = NormalizeEscapes(current, host_len);
StringLower(host);
parsed_uri->host = host;
len += host_len;
if (current[host_len] == ':') {
// The ':' character precedes the optional port string.
const char* port_start = current + host_len + 1; // +1 for ':'
size_t port_len = strcspn(port_start, "/");
parsed_uri->port = zone->MakeCopyOfStringN(port_start, port_len);
len += 1 + port_len; // +1 for ':'
} else {
parsed_uri->port = NULL;
}
return len;
}
// Performs a simple parse of a uri into its components.
// See RFC 3986 Section 3: Syntax.
bool ParseUri(const char* uri, ParsedUri* parsed_uri) {
Zone* zone = Thread::Current()->zone();
// The first ':' separates the scheme from the rest of the uri. If
// a ':' occurs after the first '/' it doesn't count.
size_t scheme_len = strcspn(uri, ":/");
const char* rest = uri;
if (uri[scheme_len] == ':') {
char* scheme = zone->MakeCopyOfStringN(uri, scheme_len);
StringLower(scheme);
parsed_uri->scheme = scheme;
rest = uri + scheme_len + 1;
} else {
parsed_uri->scheme = NULL;
}
// The first '#' separates the optional fragment
const char* hash_pos = rest + strcspn(rest, "#");
if (*hash_pos == '#') {
// There is a fragment part.
const char* fragment_start = hash_pos + 1;
parsed_uri->fragment =
NormalizeEscapes(fragment_start, strlen(fragment_start));
} else {
parsed_uri->fragment = NULL;
}
// The first '?' or '#' separates the hierarchical part from the
// optional query.
const char* question_pos = rest + strcspn(rest, "?#");
if (*question_pos == '?') {
// There is a query part.
const char* query_start = question_pos + 1;
parsed_uri->query = NormalizeEscapes(query_start, (hash_pos - query_start));
} else {
parsed_uri->query = NULL;
}
const char* path_start = rest;
if (rest[0] == '/' && rest[1] == '/') {
// There is an authority part.
const char* authority_start = rest + 2; // 2 for '//'.
intptr_t authority_len = ParseAuthority(authority_start, parsed_uri);
if (authority_len < 0) {
ClearParsedUri(parsed_uri);
return false;
}
path_start = authority_start + authority_len;
} else {
parsed_uri->userinfo = NULL;
parsed_uri->host = NULL;
parsed_uri->port = NULL;
}
// The path is the substring between the authority and the query.
parsed_uri->path = NormalizeEscapes(path_start, (question_pos - path_start));
return true;
}
static char* RemoveLastSegment(char* current, char* base) {
if (current == base) {
return current;
}
ASSERT(current > base);
for (current--; current > base; current--) {
if (*current == '/') {
// We have found the beginning of the last segment.
return current;
}
}
ASSERT(current == base);
return current;
}
static intptr_t SegmentLength(const char* input) {
const char* cp = input;
// Include initial slash in the segment, if any.
if (*cp == '/') {
cp++;
}
// Don't include trailing slash in the segment.
cp += strcspn(cp, "/");
return cp - input;
}
// See RFC 3986 Section 5.2.4: Remove Dot Segments.
static const char* RemoveDotSegments(const char* path) {
const char* input = path;
// The output path will always be less than or equal to the size of
// the input path.
Zone* zone = Thread::Current()->zone();
char* buffer = zone->Alloc<char>(strlen(path) + 1); // +1 for '\0'
char* output = buffer;
while (*input != '\0') {
if (strncmp("../", input, 3) == 0) {
// Discard initial "../" from the input. It's junk.
input += 3;
} else if (strncmp("./", input, 3) == 0) {
// Discard initial "./" from the input. It's junk.
input += 2;
} else if (strncmp("/./", input, 3) == 0) {
// Advance past the "/." part of the input.
input += 2;
} else if (strcmp("/.", input) == 0) {
// Pretend the input just contains a "/".
input = "/";
} else if (strncmp("/../", input, 4) == 0) {
// Advance past the "/.." part of the input and remove one
// segment from the output.
input += 3;
output = RemoveLastSegment(output, buffer);
} else if (strcmp("/..", input) == 0) {
// Pretend the input contains a "/" and remove one segment from
// the output.
input = "/";
output = RemoveLastSegment(output, buffer);
} else if (strcmp("..", input) == 0) {
// The input has been reduced to nothing useful.
input += 2;
} else if (strcmp(".", input) == 0) {
// The input has been reduced to nothing useful.
input += 1;
} else {
intptr_t segment_len = SegmentLength(input);
if (input[0] != '/' && output != buffer) {
*output = '/';
output++;
}
strncpy(output, input, segment_len);
output += segment_len;
input += segment_len;
}
}
*output = '\0';
return buffer;
}
// See RFC 3986 Section 5.2.3: Merge Paths.
static const char* MergePaths(const char* base_path, const char* ref_path) {
Zone* zone = Thread::Current()->zone();
if (base_path[0] == '\0') {
// If the base_path is empty, we prepend '/'.
return zone->PrintToString("/%s", ref_path);
}
// We need to find the last '/' in base_path.
const char* last_slash = strrchr(base_path, '/');
if (last_slash == NULL) {
// There is no slash in the base_path. Return the ref_path unchanged.
return ref_path;
}
// We found a '/' in the base_path. Cut off everything after it and
// add the ref_path.
intptr_t truncated_base_len = last_slash - base_path;
intptr_t ref_path_len = strlen(ref_path);
intptr_t len = truncated_base_len + ref_path_len + 1; // +1 for '/'
char* buffer = zone->Alloc<char>(len + 1); // +1 for '\0'
// Copy truncated base.
strncpy(buffer, base_path, truncated_base_len);
// Add a slash.
buffer[truncated_base_len] = '/';
// Copy the ref_path.
strncpy((buffer + truncated_base_len + 1), ref_path, ref_path_len);
// Add the trailing '\0'.
buffer[len] = '\0';
return buffer;
}
static char* BuildUri(const ParsedUri& uri) {
Zone* zone = Thread::Current()->zone();
ASSERT(uri.path != NULL);
const char* fragment = uri.fragment == NULL ? "" : uri.fragment;
const char* fragment_separator = uri.fragment == NULL ? "" : "#";
const char* query = uri.query == NULL ? "" : uri.query;
const char* query_separator = uri.query == NULL ? "" : "?";
// If there is no scheme for this uri, just build a relative uri of
// the form: "path[?query][#fragment]". This occurs when we resolve
// relative urls inside a "dart:" library.
if (uri.scheme == NULL) {
ASSERT(uri.userinfo == NULL && uri.host == NULL && uri.port == NULL);
return zone->PrintToString("%s%s%s%s%s", uri.path, query_separator, query,
fragment_separator, fragment);
}
// Uri with no authority: "scheme:path[?query][#fragment]"
if (uri.host == NULL) {
ASSERT(uri.userinfo == NULL && uri.port == NULL);
return zone->PrintToString("%s:%s%s%s%s%s", uri.scheme, uri.path,
query_separator, query, fragment_separator,
fragment);
}
const char* user = uri.userinfo == NULL ? "" : uri.userinfo;
const char* user_separator = uri.userinfo == NULL ? "" : "@";
const char* port = uri.port == NULL ? "" : uri.port;
const char* port_separator = uri.port == NULL ? "" : ":";
// If the path doesn't start with a '/', add one. We need it to
// separate the path from the authority.
const char* path_separator =
((uri.path[0] == '\0' || uri.path[0] == '/') ? "" : "/");
// Uri with authority:
// "scheme://[userinfo@]host[:port][/]path[?query][#fragment]"
return zone->PrintToString(
"%s://%s%s%s%s%s%s%s%s%s%s%s", // There is *nothing* wrong with this.
uri.scheme, user, user_separator, uri.host, port_separator, port,
path_separator, uri.path, query_separator, query, fragment_separator,
fragment);
}
// See RFC 3986 Section 5: Reference Resolution
bool ResolveUri(const char* ref_uri,
const char* base_uri,
const char** target_uri) {
// Parse the reference uri.
ParsedUri ref;
if (!ParseUri(ref_uri, &ref)) {
*target_uri = NULL;
return false;
}
ParsedUri target;
if (ref.scheme != NULL) {
if (strcmp(ref.scheme, "dart") == 0) {
Zone* zone = Thread::Current()->zone();
*target_uri = zone->MakeCopyOfString(ref_uri);
return true;
}
// When the ref_uri specifies a scheme, the base_uri is ignored.
target.scheme = ref.scheme;
target.userinfo = ref.userinfo;
target.host = ref.host;
target.port = ref.port;
target.path = RemoveDotSegments(ref.path);
target.query = ref.query;
target.fragment = ref.fragment;
*target_uri = BuildUri(target);
return true;
}
// Parse the base uri.
ParsedUri base;
if (!ParseUri(base_uri, &base)) {
*target_uri = NULL;
return false;
}
if ((base.scheme != NULL) && strcmp(base.scheme, "dart") == 0) {
Zone* zone = Thread::Current()->zone();
*target_uri = zone->MakeCopyOfString(ref_uri);
return true;
}
if (ref.host != NULL) {
// When the ref_uri specifies an authority, we only use the base scheme.
target.scheme = base.scheme;
target.userinfo = ref.userinfo;
target.host = ref.host;
target.port = ref.port;
target.path = RemoveDotSegments(ref.path);
target.query = ref.query;
target.fragment = ref.fragment;
*target_uri = BuildUri(target);
return true;
}
if (ref.path[0] == '\0') {
// Empty path. Use most parts of base_uri.
target.scheme = base.scheme;
target.userinfo = base.userinfo;
target.host = base.host;
target.port = base.port;
target.path = base.path;
target.query = ((ref.query == NULL) ? base.query : ref.query);
target.fragment = ref.fragment;
*target_uri = BuildUri(target);
return true;
} else if (ref.path[0] == '/') {
// Absolute path. ref_path wins.
target.scheme = base.scheme;
target.userinfo = base.userinfo;
target.host = base.host;
target.port = base.port;
target.path = RemoveDotSegments(ref.path);
target.query = ref.query;
target.fragment = ref.fragment;
*target_uri = BuildUri(target);
return true;
} else {
// Relative path. We need to merge the base path and the ref path.
if (base.scheme == NULL && base.host == NULL && base.path[0] != '/') {
// The dart:core Uri class handles resolving a relative uri
// against a second relative uri specially, in a way not
// described in the RFC. We do not need to support this for
// library resolution. If we need to implement this later, we
// can.
*target_uri = NULL;
return false;
}
target.scheme = base.scheme;
target.userinfo = base.userinfo;
target.host = base.host;
target.port = base.port;
target.path = RemoveDotSegments(MergePaths(base.path, ref.path));
target.query = ref.query;
target.fragment = ref.fragment;
*target_uri = BuildUri(target);
return true;
}
}
} // namespace dart