/*
 * Copyright (c) 2009-2014 Kazuho Oku, Tokuhiro Matsuno, Daisuke Murase,
 *                         Shigeo Mitsunari
 *
 * SPDX-License-Identifier: MIT
 *
 * The software is licensed under either the MIT License (below) or the Perl
 * license.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
 * deal in the Software without restriction, including without limitation the
 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
 * sell copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 */

#include <assert.h>
#include <stddef.h>
#include <string.h>
#ifdef __SSE4_2__
#ifdef _MSC_VER
#include <nmmintrin.h>
#else
#include <x86intrin.h>
#endif
#endif
#include "picohttpparser.h"

#if __GNUC__ >= 3
#define likely(x)   __builtin_expect(!!(x), 1)
#define unlikely(x) __builtin_expect(!!(x), 0)
#else
#define likely(x)   (x)
#define unlikely(x) (x)
#endif

#ifdef _MSC_VER
#define ALIGNED(n) _declspec(align(n))
#else
#define ALIGNED(n) __attribute__((aligned(n)))
#endif

#define IS_PRINTABLE_ASCII(c) ((unsigned char)(c) - 040u < 0137u)

#define CHECK_EOF()           \
	if (buf == buf_end) { \
		*ret = -2;    \
		return NULL;  \
	}

#define EXPECT_CHAR_NO_CHECK(ch) \
	if (*buf++ != ch) {      \
		*ret = -1;       \
		return NULL;     \
	}

#define EXPECT_CHAR(ch) \
	CHECK_EOF();    \
	EXPECT_CHAR_NO_CHECK(ch);

#define ADVANCE_TOKEN(tok, toklen)                                        \
	do {                                                              \
		const char *tok_start = buf;                              \
		static const char ALIGNED(16)                             \
			ranges2[16] = "\000\040\177\177";                 \
		int found2;                                               \
		buf = findchar_fast(buf, buf_end, ranges2, 4, &found2);   \
		if (!found2) {                                            \
			CHECK_EOF();                                      \
		}                                                         \
		while (1) {                                               \
			if (*buf == ' ') {                                \
				break;                                    \
			} else if (unlikely(!IS_PRINTABLE_ASCII(*buf))) { \
				if ((unsigned char)*buf < '\040' ||       \
				    *buf == '\177')                       \
				{                                         \
					*ret = -1;                        \
					return NULL;                      \
				}                                         \
			}                                                 \
			++buf;                                            \
			CHECK_EOF();                                      \
		}                                                         \
		tok = tok_start;                                          \
		toklen = buf - tok_start;                                 \
	} while (0)

static const char *token_char_map =
	"\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"
	"\0\1\0\1\1\1\1\1\0\0\1\1\0\1\1\0\1\1\1\1\1\1\1\1\1\1\0\0\0\0\0\0"
	"\0\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\0\0\0\1\1"
	"\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\0\1\0\1\0"
	"\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"
	"\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"
	"\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"
	"\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0";

static const char *
findchar_fast(const char *buf, const char *buf_end, const char *ranges,
	      size_t ranges_size, int *found) {
	*found = 0;
#if __SSE4_2__
	if (likely(buf_end - buf >= 16)) {
		__m128i ranges16 = _mm_loadu_si128((const __m128i *)ranges);

		size_t left = (buf_end - buf) & ~15;
		do {
			__m128i b16 = _mm_loadu_si128((const __m128i *)buf);
			int r = _mm_cmpestri(ranges16, ranges_size, b16, 16,
					     _SIDD_LEAST_SIGNIFICANT |
						     _SIDD_CMP_RANGES |
						     _SIDD_UBYTE_OPS);
			if (unlikely(r != 16)) {
				buf += r;
				*found = 1;
				break;
			}
			buf += 16;
			left -= 16;
		} while (likely(left != 0));
	}
#else
	/* suppress unused parameter warning */
	(void)buf_end;
	(void)ranges;
	(void)ranges_size;
#endif
	return buf;
}

static const char *
get_token_to_eol(const char *buf, const char *buf_end, const char **token,
		 size_t *token_len, int *ret) {
	const char *token_start = buf;

#ifdef __SSE4_2__
	static const char ALIGNED(16)
		ranges1[16] = "\0\010"	 /* allow HT */
			      "\012\037" /* allow SP and up to but not including
					    DEL */
			      "\177\177"; /* allow chars w. MSB set */
	int found;
	buf = findchar_fast(buf, buf_end, ranges1, 6, &found);
	if (found) {
		goto FOUND_CTL;
	}
#else
	/* find non-printable char within the next 8 bytes, this is the hottest
	 * code; manually inlined */
	while (likely(buf_end - buf >= 8)) {
#define DOIT()                                             \
	do {                                               \
		if (unlikely(!IS_PRINTABLE_ASCII(*buf))) { \
			goto NonPrintable;                 \
		}                                          \
		++buf;                                     \
	} while (0)
		DOIT();
		DOIT();
		DOIT();
		DOIT();
		DOIT();
		DOIT();
		DOIT();
		DOIT();
#undef DOIT
		continue;
	NonPrintable:
		if ((likely((unsigned char)*buf < '\040') &&
		     likely(*buf != '\011')) ||
		    unlikely(*buf == '\177'))
		{
			goto FOUND_CTL;
		}
		++buf;
	}
#endif
	for (;; ++buf) {
		CHECK_EOF();
		if (unlikely(!IS_PRINTABLE_ASCII(*buf))) {
			if ((likely((unsigned char)*buf < '\040') &&
			     likely(*buf != '\011')) ||
			    unlikely(*buf == '\177'))
			{
				goto FOUND_CTL;
			}
		}
	}
FOUND_CTL:
	if (likely(*buf == '\015')) {
		++buf;
		EXPECT_CHAR('\012');
		*token_len = buf - 2 - token_start;
	} else if (*buf == '\012') {
		*token_len = buf - token_start;
		++buf;
	} else {
		*ret = -1;
		return NULL;
	}
	*token = token_start;

	return buf;
}

static const char *
is_complete(const char *buf, const char *buf_end, size_t last_len, int *ret) {
	int ret_cnt = 0;
	buf = last_len < 3 ? buf : buf + last_len - 3;

	while (1) {
		CHECK_EOF();
		if (*buf == '\015') {
			++buf;
			CHECK_EOF();
			EXPECT_CHAR('\012');
			++ret_cnt;
		} else if (*buf == '\012') {
			++buf;
			++ret_cnt;
		} else {
			++buf;
			ret_cnt = 0;
		}
		if (ret_cnt == 2) {
			return buf;
		}
	}

	*ret = -2;
	return NULL;
}

#define PARSE_INT(valp_, mul_)          \
	if (*buf < '0' || '9' < *buf) { \
		buf++;                  \
		*ret = -1;              \
		return NULL;            \
	}                               \
	*(valp_) = (mul_) * (*buf++ - '0');

#define PARSE_INT_3(valp_)            \
	do {                          \
		int res_ = 0;         \
		PARSE_INT(&res_, 100) \
		*valp_ = res_;        \
		PARSE_INT(&res_, 10)  \
		*valp_ += res_;       \
		PARSE_INT(&res_, 1)   \
		*valp_ += res_;       \
	} while (0)

/* returned pointer is always within [buf, buf_end), or null */
static const char *
parse_token(const char *buf, const char *buf_end, const char **token,
	    size_t *token_len, char next_char, int *ret) {
	/* We use pcmpestri to detect non-token characters. This instruction can
	 * take no more than eight character ranges (8*2*8=128 bits that is the
	 * size of a SSE register). Due to this restriction, characters `|` and
	 * `~` are handled in the slow loop. */
	static const char ALIGNED(16) ranges[] = "\x00 " /* control chars and up
							    to SP */
						 "\"\""	 /* 0x22 */
						 "()"	 /* 0x28,0x29 */
						 ",,"	 /* 0x2c */
						 "//"	 /* 0x2f */
						 ":@"	 /* 0x3a-0x40 */
						 "[]"	 /* 0x5b-0x5d */
						 "{\xff"; /* 0x7b-0xff */
	const char *buf_start = buf;
	int found;
	buf = findchar_fast(buf, buf_end, ranges, sizeof(ranges) - 1, &found);
	if (!found) {
		CHECK_EOF();
	}
	while (1) {
		if (*buf == next_char) {
			break;
		} else if (!token_char_map[(unsigned char)*buf]) {
			*ret = -1;
			return NULL;
		}
		++buf;
		CHECK_EOF();
	}
	*token = buf_start;
	*token_len = buf - buf_start;
	return buf;
}

/* returned pointer is always within [buf, buf_end), or null */
static const char *
parse_http_version(const char *buf, const char *buf_end, int *minor_version,
		   int *ret) {
	/* we want at least [HTTP/1.<two chars>] to try to parse */
	if (buf_end - buf < 9) {
		*ret = -2;
		return NULL;
	}
	EXPECT_CHAR_NO_CHECK('H');
	EXPECT_CHAR_NO_CHECK('T');
	EXPECT_CHAR_NO_CHECK('T');
	EXPECT_CHAR_NO_CHECK('P');
	EXPECT_CHAR_NO_CHECK('/');
	EXPECT_CHAR_NO_CHECK('1');
	EXPECT_CHAR_NO_CHECK('.');
	PARSE_INT(minor_version, 1);
	return buf;
}

static const char *
parse_headers(const char *buf, const char *buf_end, struct phr_header *headers,
	      size_t *num_headers, size_t max_headers, int *ret) {
	for (;; ++*num_headers) {
		CHECK_EOF();
		if (*buf == '\015') {
			++buf;
			EXPECT_CHAR('\012');
			break;
		} else if (*buf == '\012') {
			++buf;
			break;
		}
		if (*num_headers == max_headers) {
			*ret = -1;
			return NULL;
		}
		if (!(*num_headers != 0 && (*buf == ' ' || *buf == '\t'))) {
			/* parsing name, but do not discard SP before colon, see
			 * http://www.mozilla.org/security/announce/2006/mfsa2006-33.html
			 */
			if ((buf = parse_token(buf, buf_end,
					       &headers[*num_headers].name,
					       &headers[*num_headers].name_len,
					       ':', ret)) == NULL)
			{
				return NULL;
			}
			if (headers[*num_headers].name_len == 0) {
				*ret = -1;
				return NULL;
			}
			++buf;
			for (;; ++buf) {
				CHECK_EOF();
				if (!(*buf == ' ' || *buf == '\t')) {
					break;
				}
			}
		} else {
			headers[*num_headers].name = NULL;
			headers[*num_headers].name_len = 0;
		}
		const char *value;
		size_t value_len;
		if ((buf = get_token_to_eol(buf, buf_end, &value, &value_len,
					    ret)) == NULL)
		{
			return NULL;
		}
		/* remove trailing SPs and HTABs */
		const char *value_end = value + value_len;
		for (; value_end != value; --value_end) {
			const char c = *(value_end - 1);
			if (!(c == ' ' || c == '\t')) {
				break;
			}
		}
		headers[*num_headers].value = value;
		headers[*num_headers].value_len = value_end - value;
	}
	return buf;
}

static const char *
parse_request(const char *buf, const char *buf_end, const char **method,
	      size_t *method_len, const char **path, size_t *path_len,
	      int *minor_version, struct phr_header *headers,
	      size_t *num_headers, size_t max_headers, int *ret) {
	/* skip first empty line (some clients add CRLF after POST content) */
	CHECK_EOF();
	if (*buf == '\015') {
		++buf;
		EXPECT_CHAR('\012');
	} else if (*buf == '\012') {
		++buf;
	}

	/* parse request line */
	if ((buf = parse_token(buf, buf_end, method, method_len, ' ', ret)) ==
	    NULL)
	{
		return NULL;
	}
	do {
		++buf;
		CHECK_EOF();
	} while (*buf == ' ');
	ADVANCE_TOKEN(*path, *path_len);
	do {
		++buf;
		CHECK_EOF();
	} while (*buf == ' ');
	if (*method_len == 0 || *path_len == 0) {
		*ret = -1;
		return NULL;
	}
	if ((buf = parse_http_version(buf, buf_end, minor_version, ret)) ==
	    NULL)
	{
		return NULL;
	}
	if (*buf == '\015') {
		++buf;
		EXPECT_CHAR('\012');
	} else if (*buf == '\012') {
		++buf;
	} else {
		*ret = -1;
		return NULL;
	}

	return parse_headers(buf, buf_end, headers, num_headers, max_headers,
			     ret);
}

int
phr_parse_request(const char *buf_start, size_t len, const char **method,
		  size_t *method_len, const char **path, size_t *path_len,
		  int *minor_version, struct phr_header *headers,
		  size_t *num_headers, size_t last_len) {
	const char *buf = buf_start, *buf_end = buf_start + len;
	size_t max_headers = *num_headers;
	int r = -1;

	*method = NULL;
	*method_len = 0;
	*path = NULL;
	*path_len = 0;
	*minor_version = -1;
	*num_headers = 0;

	/* if last_len != 0, check if the request is complete (a fast
	   countermeasure againt slowloris */
	if (last_len != 0 && is_complete(buf, buf_end, last_len, &r) == NULL) {
		return r;
	}

	if ((buf = parse_request(buf, buf_end, method, method_len, path,
				 path_len, minor_version, headers, num_headers,
				 max_headers, &r)) == NULL)
	{
		return r;
	}

	return (int)(buf - buf_start);
}

static const char *
parse_response(const char *buf, const char *buf_end, int *minor_version,
	       int *status, const char **msg, size_t *msg_len,
	       struct phr_header *headers, size_t *num_headers,
	       size_t max_headers, int *ret) {
	/* parse "HTTP/1.x" */
	if ((buf = parse_http_version(buf, buf_end, minor_version, ret)) ==
	    NULL)
	{
		return NULL;
	}
	/* skip space */
	if (*buf != ' ') {
		*ret = -1;
		return NULL;
	}
	do {
		++buf;
		CHECK_EOF();
	} while (*buf == ' ');
	/* parse status code, we want at least [:digit:][:digit:][:digit:]<other
	 * char> to try to parse */
	if (buf_end - buf < 4) {
		*ret = -2;
		return NULL;
	}
	PARSE_INT_3(status);

	/* get message including preceding space */
	if ((buf = get_token_to_eol(buf, buf_end, msg, msg_len, ret)) == NULL) {
		return NULL;
	}
	if (*msg_len == 0) {
		/* ok */
	} else if (**msg == ' ') {
		/* Remove preceding space. Successful return from
		 * `get_token_to_eol` guarantees that we would hit something
		 * other than SP before running past the end of the given
		 * buffer. */
		do {
			++*msg;
			--*msg_len;
		} while (**msg == ' ');
	} else {
		/* garbage found after status code */
		*ret = -1;
		return NULL;
	}

	return parse_headers(buf, buf_end, headers, num_headers, max_headers,
			     ret);
}

int
phr_parse_response(const char *buf_start, size_t len, int *minor_version,
		   int *status, const char **msg, size_t *msg_len,
		   struct phr_header *headers, size_t *num_headers,
		   size_t last_len) {
	const char *buf = buf_start, *buf_end = buf + len;
	size_t max_headers = *num_headers;
	int r;

	*minor_version = -1;
	*status = 0;
	*msg = NULL;
	*msg_len = 0;
	*num_headers = 0;

	/* if last_len != 0, check if the response is complete (a fast
	   countermeasure against slowloris */
	if (last_len != 0 && is_complete(buf, buf_end, last_len, &r) == NULL) {
		return r;
	}

	if ((buf = parse_response(buf, buf_end, minor_version, status, msg,
				  msg_len, headers, num_headers, max_headers,
				  &r)) == NULL)
	{
		return r;
	}

	return (int)(buf - buf_start);
}

int
phr_parse_headers(const char *buf_start, size_t len, struct phr_header *headers,
		  size_t *num_headers, size_t last_len) {
	const char *buf = buf_start, *buf_end = buf + len;
	size_t max_headers = *num_headers;
	int r;

	*num_headers = 0;

	/* if last_len != 0, check if the response is complete (a fast
	   countermeasure against slowloris */
	if (last_len != 0 && is_complete(buf, buf_end, last_len, &r) == NULL) {
		return r;
	}

	if ((buf = parse_headers(buf, buf_end, headers, num_headers,
				 max_headers, &r)) == NULL)
	{
		return r;
	}

	return (int)(buf - buf_start);
}

enum {
	CHUNKED_IN_CHUNK_SIZE,
	CHUNKED_IN_CHUNK_EXT,
	CHUNKED_IN_CHUNK_HEADER_EXPECT_LF,
	CHUNKED_IN_CHUNK_DATA,
	CHUNKED_IN_CHUNK_DATA_EXPECT_CR,
	CHUNKED_IN_CHUNK_DATA_EXPECT_LF,
	CHUNKED_IN_TRAILERS_LINE_HEAD,
	CHUNKED_IN_TRAILERS_LINE_MIDDLE
};

static int
decode_hex(int ch) {
	if ('0' <= ch && ch <= '9') {
		return ch - '0';
	} else if ('A' <= ch && ch <= 'F') {
		return ch - 'A' + 0xa;
	} else if ('a' <= ch && ch <= 'f') {
		return ch - 'a' + 0xa;
	} else {
		return -1;
	}
}

ssize_t
phr_decode_chunked(struct phr_chunked_decoder *decoder, char *buf,
		   size_t *_bufsz) {
	size_t dst = 0, src = 0, bufsz = *_bufsz;
	ssize_t ret = -2; /* incomplete */

	decoder->_total_read += bufsz;

	while (1) {
		switch (decoder->_state) {
		case CHUNKED_IN_CHUNK_SIZE:
			for (;; ++src) {
				int v;
				if (src == bufsz) {
					goto Exit;
				}
				if ((v = decode_hex(buf[src])) == -1) {
					if (decoder->_hex_count == 0) {
						ret = -1;
						goto Exit;
					}
					/* the only characters that may appear
					 * after the chunk size are BWS,
					 * semicolon, or CRLF */
					switch (buf[src]) {
					case ' ':
					case '\011':
					case ';':
					case '\012':
					case '\015':
						break;
					default:
						ret = -1;
						goto Exit;
					}
					break;
				}
				if (decoder->_hex_count == sizeof(size_t) * 2) {
					ret = -1;
					goto Exit;
				}
				decoder->bytes_left_in_chunk =
					decoder->bytes_left_in_chunk * 16 + v;
				++decoder->_hex_count;
			}
			decoder->_hex_count = 0;
			decoder->_state = CHUNKED_IN_CHUNK_EXT;
		/* fall through */
		case CHUNKED_IN_CHUNK_EXT:
			/* RFC 7230 A.2 "Line folding in chunk extensions is
			 * disallowed" */
			for (;; ++src) {
				if (src == bufsz) {
					goto Exit;
				}
				if (buf[src] == '\015') {
					break;
				} else if (buf[src] == '\012') {
					ret = -1;
					goto Exit;
				}
			}
			++src;
			decoder->_state = CHUNKED_IN_CHUNK_HEADER_EXPECT_LF;
		/* fall through */
		case CHUNKED_IN_CHUNK_HEADER_EXPECT_LF:
			if (src == bufsz) {
				goto Exit;
			}
			if (buf[src] != '\012') {
				ret = -1;
				goto Exit;
			}
			++src;
			if (decoder->bytes_left_in_chunk == 0) {
				if (decoder->consume_trailer) {
					decoder->_state =
						CHUNKED_IN_TRAILERS_LINE_HEAD;
					break;
				} else {
					goto Complete;
				}
			}
			decoder->_state = CHUNKED_IN_CHUNK_DATA;
		/* fall through */
		case CHUNKED_IN_CHUNK_DATA: {
			size_t avail = bufsz - src;
			if (avail < decoder->bytes_left_in_chunk) {
				if (dst != src) {
					memmove(buf + dst, buf + src, avail);
				}
				src += avail;
				dst += avail;
				decoder->bytes_left_in_chunk -= avail;
				goto Exit;
			}
			if (dst != src) {
				memmove(buf + dst, buf + src,
					decoder->bytes_left_in_chunk);
			}
			src += decoder->bytes_left_in_chunk;
			dst += decoder->bytes_left_in_chunk;
			decoder->bytes_left_in_chunk = 0;
			decoder->_state = CHUNKED_IN_CHUNK_DATA_EXPECT_CR;
		}
		/* fall through */
		case CHUNKED_IN_CHUNK_DATA_EXPECT_CR:
			if (src == bufsz) {
				goto Exit;
			}
			if (buf[src] != '\015') {
				ret = -1;
				goto Exit;
			}
			++src;
			decoder->_state = CHUNKED_IN_CHUNK_DATA_EXPECT_LF;
		/* fall through */
		case CHUNKED_IN_CHUNK_DATA_EXPECT_LF:
			if (src == bufsz) {
				goto Exit;
			}
			if (buf[src] != '\012') {
				ret = -1;
				goto Exit;
			}
			++src;
			decoder->_state = CHUNKED_IN_CHUNK_SIZE;
			break;
		case CHUNKED_IN_TRAILERS_LINE_HEAD:
			for (;; ++src) {
				if (src == bufsz) {
					goto Exit;
				}
				if (buf[src] != '\015') {
					break;
				}
			}
			if (buf[src++] == '\012') {
				goto Complete;
			}
			decoder->_state = CHUNKED_IN_TRAILERS_LINE_MIDDLE;
		/* fall through */
		case CHUNKED_IN_TRAILERS_LINE_MIDDLE:
			for (;; ++src) {
				if (src == bufsz) {
					goto Exit;
				}
				if (buf[src] == '\012') {
					break;
				}
			}
			++src;
			decoder->_state = CHUNKED_IN_TRAILERS_LINE_HEAD;
			break;
		default:
			assert(!"decoder is corrupt");
		}
	}

Complete:
	ret = bufsz - src;
Exit:
	if (dst != src) {
		memmove(buf + dst, buf + src, bufsz - src);
	}
	*_bufsz = dst;
	/* if incomplete but the overhead of the chunked encoding is >=100KB and
	 * >80%, signal an error */
	if (ret == -2) {
		decoder->_total_overhead += bufsz - dst;
		if (decoder->_total_overhead >= 100 * 1024 &&
		    decoder->_total_read - decoder->_total_overhead <
			    decoder->_total_read / 4)
		{
			ret = -1;
		}
	}
	return ret;
}

int
phr_decode_chunked_is_in_data(struct phr_chunked_decoder *decoder) {
	return decoder->_state == CHUNKED_IN_CHUNK_DATA;
}

#undef CHECK_EOF
#undef EXPECT_CHAR
#undef ADVANCE_TOKEN
