Merge HTTP request / response parsing code

This change also fixes a bug so that DNS lookups work correctly when the
first answer is a CNAME record.
This commit is contained in:
Justine Tunney 2021-06-27 17:03:06 -07:00
parent 5a6c0f27c3
commit a68cc690ff
20 changed files with 561 additions and 616 deletions

278
net/http/parsehttpmessage.c Normal file
View file

@ -0,0 +1,278 @@
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi
Copyright 2020 Justine Alexandra Roberts Tunney
Permission to use, copy, modify, and/or distribute this software for
any purpose with or without fee is hereby granted, provided that the
above copyright notice and this permission notice appear in all copies.
THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
PERFORMANCE OF THIS SOFTWARE.
*/
#include "libc/alg/alg.h"
#include "libc/alg/arraylist.internal.h"
#include "libc/assert.h"
#include "libc/bits/bits.h"
#include "libc/limits.h"
#include "libc/macros.internal.h"
#include "libc/mem/mem.h"
#include "libc/stdio/stdio.h"
#include "libc/str/str.h"
#include "libc/sysv/errfuns.h"
#include "libc/x/x.h"
#include "net/http/http.h"
#define LIMIT (SHRT_MAX - 2)
enum HttpMessageState {
START,
METHOD,
URI,
VERSION,
STATUS,
MESSAGE,
HKEY,
HSEP,
HVAL,
CR1,
LF1,
LF2,
};
/**
* Initializes HTTP message parser.
*/
void InitHttpMessage(struct HttpMessage *r, int type) {
assert(type == kHttpRequest || type == kHttpResponse);
memset(r, 0, sizeof(*r));
r->type = type;
}
/**
* Destroys HTTP message parser.
*/
void DestroyHttpMessage(struct HttpMessage *r) {
if (r->xheaders.p) {
free(r->xheaders.p);
r->xheaders.p = NULL;
r->xheaders.n = 0;
}
}
/**
* Parses HTTP request or response.
*
* This parser is responsible for determining the length of a message
* and slicing the strings inside it. Performance is attained using
* perfect hash tables. No memory allocation is performed for normal
* messages. Line folding is forbidden. State persists across calls so
* that fragmented messages can be handled efficiently. A limitation on
* message size is imposed to make the header data structures smaller.
*
* This parser assumes ISO-8859-1 and guarantees no C0 or C1 control
* codes are present in message fields, with the exception of tab.
* Please note that fields like URI may use UTF-8 percent encoding. This
* parser doesn't care if you choose ASA X3.4-1963 or MULTICS newlines.
*
* kHttpRepeatable defines which standard header fields are O(1) and
* which ones may have comma entries spilled over into xheaders. For
* most headers it's sufficient to simply check the static slice. If
* r->headers[kHttpFoo].a is zero then the header is totally absent.
*
* This parser has linear complexity. Each character only needs to be
* considered a single time. That's the case even if messages are
* fragmented. If a message is valid but incomplete, this function will
* return zero so that it can be resumed as soon as more data arrives.
*
* This parser takes about 400 nanoseconds to parse a 403 byte Chrome
* HTTP request under MODE=rel on a Core i9 which is about three cycles
* per byte or a gigabyte per second of throughput per core.
*
* @note we assume p points to a buffer that has >=SHRT_MAX bytes
* @see HTTP/1.1 RFC2616 RFC2068
* @see HTTP/1.0 RFC1945
*/
int ParseHttpMessage(struct HttpMessage *r, const char *p, size_t n) {
int c, h, i;
struct HttpHeader *x;
for (n = MIN(n, LIMIT); r->i < n; ++r->i) {
c = p[r->i] & 0xff;
switch (r->t) {
case START:
if (c == '\r' || c == '\n') break; /* RFC7230 § 3.5 */
if (!kHttpToken[c]) return ebadmsg();
r->t = r->type == kHttpRequest ? METHOD : VERSION;
r->a = r->i;
break;
case METHOD:
for (;;) {
if (c == ' ') {
r->method = GetHttpMethod(p + r->a, r->i - r->a);
r->xmethod.a = r->a;
r->xmethod.b = r->i;
r->a = r->i + 1;
r->t = URI;
break;
} else if (!kHttpToken[c]) {
return ebadmsg();
}
if (++r->i == n) break;
c = p[r->i] & 0xff;
}
break;
case URI:
for (;;) {
if (c == ' ' || c == '\r' || c == '\n') {
if (r->i == r->a) return ebadmsg();
r->uri.a = r->a;
r->uri.b = r->i;
if (c == ' ') {
r->a = r->i + 1;
r->t = VERSION;
} else {
r->version = 9;
r->t = c == '\r' ? CR1 : LF1;
}
break;
} else if (c < 0x20 || (0x7F <= c && c < 0xA0)) {
return ebadmsg();
}
if (++r->i == n) break;
c = p[r->i] & 0xff;
}
break;
case VERSION:
if (c == ' ' || c == '\r' || c == '\n') {
if (r->i - r->a == 8 &&
(READ64BE(p + r->a) & 0xFFFFFFFFFF00FF00) == 0x485454502F002E00 &&
isdigit(p[r->a + 5]) && isdigit(p[r->a + 7])) {
r->version = (p[r->a + 5] - '0') * 10 + (p[r->a + 7] - '0');
if (r->type == kHttpRequest) {
r->t = c == '\r' ? CR1 : LF1;
} else {
r->t = STATUS;
}
} else {
return ebadmsg();
}
}
break;
case STATUS:
for (;;) {
if (c == ' ' || c == '\r' || c == '\n') {
if (r->status < 100) return ebadmsg();
if (c == ' ') {
r->a = r->i + 1;
r->t = MESSAGE;
} else {
r->t = c == '\r' ? CR1 : LF1;
}
break;
} else if ('0' <= c && c <= '9') {
r->status *= 10;
r->status += c - '0';
if (r->status > 999) return ebadmsg();
} else {
return ebadmsg();
}
if (++r->i == n) break;
c = p[r->i] & 0xff;
}
break;
case MESSAGE:
for (;;) {
if (c == '\r' || c == '\n') {
r->message.a = r->a;
r->message.b = r->i;
r->t = c == '\r' ? CR1 : LF1;
break;
} else if (c < 0x20 || (0x7F <= c && c < 0xA0)) {
return ebadmsg();
}
if (++r->i == n) break;
c = p[r->i] & 0xff;
}
break;
case CR1:
if (c != '\n') return ebadmsg();
r->t = LF1;
break;
case LF1:
if (c == '\r') {
r->t = LF2;
break;
} else if (c == '\n') {
return ++r->i;
} else if (!kHttpToken[c]) {
return ebadmsg(); /* RFC7230 § 3.2.4 */
}
r->k.a = r->i;
r->t = HKEY;
break;
case HKEY:
for (;;) {
if (c == ':') {
r->k.b = r->i;
r->t = HSEP;
break;
} else if (!kHttpToken[c]) {
return ebadmsg();
}
if (++r->i == n) break;
c = p[r->i] & 0xff;
}
break;
case HSEP:
if (c == ' ' || c == '\t') break;
r->a = r->i;
r->t = HVAL;
/* fallthrough */
case HVAL:
for (;;) {
if (c == '\r' || c == '\n') {
i = r->i;
while (i > r->a && (p[i - 1] == ' ' || p[i - 1] == '\t')) --i;
if ((h = GetHttpHeader(p + r->k.a, r->k.b - r->k.a)) != -1 &&
(!r->headers[h].a || !kHttpRepeatable[h])) {
r->headers[h].a = r->a;
r->headers[h].b = i;
} else if ((x = realloc(
r->xheaders.p,
(r->xheaders.n + 1) * sizeof(*r->xheaders.p)))) {
x[r->xheaders.n].k = r->k;
x[r->xheaders.n].v.a = r->a;
x[r->xheaders.n].v.b = i;
r->xheaders.p = x;
++r->xheaders.n;
}
r->t = c == '\r' ? CR1 : LF1;
break;
} else if ((c < 0x20 && c != '\t') || (0x7F <= c && c < 0xA0)) {
return ebadmsg();
}
if (++r->i == n) break;
c = p[r->i] & 0xff;
}
break;
case LF2:
if (c == '\n') {
return ++r->i;
}
return ebadmsg();
default:
unreachable;
}
}
if (r->i < LIMIT) {
return 0;
} else {
return ebadmsg();
}
}