multipart.c
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multipart.c
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	#include <compat.h> // IWYU pragma: keep

	#include <stdbool.h>
	#include <stdint.h>
	#include <stdio.h>
	#include <stdlib.h>
	#include <string.h>
	#include <strings.h>

	#include "ant.h"
	#include "errors.h"
	#include "internal.h"

	#include "modules/blob.h"
	#include "modules/formdata.h"
	#include "modules/multipart.h"
	#include "modules/url.h"

	static ant_value_t multipart_invalid(ant_t *js) {
	return js_mkerr_typed(js, JS_ERR_TYPE, "Failed to parse body as FormData");
	}

	static bool ct_is_type(const char ct, const char type) {
	size_t type_len = 0;

	if (!ct \|\| !type) return false;

	while (ct == ' ' \|\| ct == '\t') ct++;
	type_len = strlen(type);
	if (strncasecmp(ct, type, type_len) != 0) return false;

	ct += type_len;
	return ct == '\0' \|\| ct == ';' \|\| ct == ' ' \|\| ct == '\t';
	}

	static const char ct_find_next_param(const char p) {
	scan:
	if (*p == '\0') return NULL;
	if (*p == ';') return p;
	if (*p != '"') {
	p++;
	goto scan;
	}

	quoted:
	p++;
	if (*p == '\0') return NULL;
	if (*p == '\\') goto escaped;
	if (*p == '"') {
	p++;
	goto scan;
	}
	goto quoted;

	escaped:
	p++;
	if (*p == '\0') return NULL;
	p++;
	goto quoted;
	}

	static char ct_get_param_dup(const char ct, const char *name) {
	const char *p = NULL;
	const char *param_name = NULL;
	const char *param_name_end = NULL;

	char *buf = NULL;
	size_t name_len = 0;
	size_t len = 0;
	size_t cap = 0;
	char ch = '\0';

	if (!ct \|\| !name) return NULL;

	name_len = strlen(name);
	if (name_len == 0) return NULL;

	p = strchr(ct, ';');

	next_param:
	if (!p) return NULL;
	p++;

	while (p == ' ' \|\| p == '\t') p++;
	if (*p == '\0') return NULL;

	param_name = p;
	while (p && p != '=' && *p != ';') p++;
	param_name_end = p;

	while (
	param_name_end > param_name &&
	(param_name_end[-1] == ' ' \|\| param_name_end[-1] == '\t')
	) param_name_end--;

	if (*p != '=') goto skip_param;
	if ((size_t)(param_name_end - param_name) != name_len) goto skip_param;
	if (strncasecmp(param_name, name, name_len) != 0) goto skip_param;

	p++;
	while (p == ' ' \|\| p == '\t') p++;
	if (*p == '\0') return strdup("");

	if (*p == '"') {
	p++;
	goto quoted;
	}

	unquoted:
	if (p == '\0' \|\| p == ';' \|\| p == ' ' \|\| p == '\t') {
	buf = malloc(len + 1);
	if (!buf) return NULL;
	if (len != 0) memcpy(buf, p - len, len);
	buf[len] = '\0';
	return buf;
	}
	p++;
	len++;
	goto unquoted;

	quoted:
	if (*p == '\0') goto fail;
	if (*p == '"') goto done;
	if (*p == '\\') goto quoted_escape;
	ch = *p++;
	goto append;

	quoted_escape:
	p++;
	if (*p == '\0') goto fail;
	ch = *p++;
	goto append;

	append:
	if (len == cap) {
	size_t next_cap = cap ? cap * 2 : 32;
	char *next = realloc(buf, next_cap);
	if (!next) goto fail;
	buf = next;
	cap = next_cap;
	}
	buf[len++] = ch;
	goto quoted;

	done:
	p++;
	if (len == cap) {
	size_t next_cap = cap ? cap + 1 : 1;
	char *next = realloc(buf, next_cap);
	if (!next) goto fail;
	buf = next;
	cap = next_cap;
	}
	buf[len] = '\0';
	return buf;

	skip_param:
	p = ct_find_next_param(p);
	goto next_param;

	fail:
	free(buf);
	return NULL;
	}

	static ant_value_t parse_formdata_urlencoded(ant_t js, const uint8_t data, size_t size) {
	ant_value_t fd = 0;
	char *body = NULL;
	char *cursor = NULL;

	fd = formdata_create_empty(js);
	if (is_err(fd)) return fd;
	if (!data \|\| size == 0) return fd;

	body = strndup((const char *)data, size);
	if (!body) return js_mkerr(js, "out of memory");

	cursor = body;
	while (cursor) {
	ant_value_t r = 0;
	char *amp = strchr(cursor, '&');
	char *eq = NULL;
	char *raw_name = NULL;
	char *raw_value = NULL;
	char *name = NULL;
	char *value = NULL;

	if (amp) *amp = '\0';

	eq = strchr(cursor, '=');
	raw_name = cursor;
	raw_value = eq ? (eq + 1) : "";
	if (eq) *eq = '\0';

	name = form_urldecode(raw_name);
	value = form_urldecode(raw_value);
	if (!name \|\| !value) {
	free(name);
	free(value);
	free(body);
	return js_mkerr(js, "out of memory");
	}

	r = formdata_append_string(
	js, fd,
	js_mkstr(js, name, strlen(name)),
	js_mkstr(js, value, strlen(value))
	);

	free(name);
	free(value);

	if (is_err(r)) {
	free(body);
	return r;
	}

	cursor = amp ? (amp + 1) : NULL;
	}

	free(body);
	return fd;
	}

	static const uint8_t *find_bytes(
	const uint8_t *haystack, size_t haystack_len,
	const uint8_t *needle, size_t needle_len
	) {
	size_t i = 0;

	if (needle_len == 0) return haystack;
	if (haystack_len < needle_len) return NULL;

	for (i = 0; i + needle_len <= haystack_len; i++) {
	if (memcmp(haystack + i, needle, needle_len) == 0) return haystack + i;
	}

	return NULL;
	}

	typedef struct {
	char *name;
	char *filename;
	char *content_type;
	} multipart_part_info_t;

	static void multipart_part_info_clear(multipart_part_info_t *info) {
	if (!info) return;
	free(info->name);
	free(info->filename);
	free(info->content_type);
	info->name = NULL;
	info->filename = NULL;
	info->content_type = NULL;
	}

	static bool multipart_parse_headers(
	ant_t js, char headers, multipart_part_info_t info, ant_value_t err_out
	) {
	char *saveptr = NULL;

	for (
	char *line = strtok_r(headers, "\r\n", &saveptr);
	line; line = strtok_r(NULL, "\r\n", &saveptr)
	) {
	char *colon = strchr(line, ':');
	char *value = NULL;

	if (!colon) continue;
	*colon = '\0';

	value = colon + 1;
	while (value == ' ' \|\| value == '\t') value++;

	if (strcasecmp(line, "Content-Disposition") == 0) {
	free(info->name);
	free(info->filename);

	info->name = ct_get_param_dup(value, "name");
	info->filename = ct_get_param_dup(value, "filename");

	continue;
	}

	if (strcasecmp(line, "Content-Type") == 0) {
	free(info->content_type);
	info->content_type = strdup(value);
	if (!info->content_type) {
	*err_out = js_mkerr(js, "out of memory");
	return false;
	}}
	}

	if (info->name) return true;
	*err_out = multipart_invalid(js);

	return false;
	}

	static const uint8_t *multipart_find_part_end(
	const uint8_t p, const uint8_t end, const char *delim, size_t delim_len
	) {
	char *marker = malloc(delim_len + 3);
	const uint8_t *part_end = NULL;
	if (!marker) return NULL;

	snprintf(marker, delim_len + 3, "\r\n%s", delim);
	part_end = find_bytes(
	p, (size_t)(end - p),
	(const uint8_t *)marker, delim_len + 2
	);

	free(marker);
	return part_end;
	}

	static ant_value_t multipart_append_part(
	ant_t js, ant_value_t fd, const multipart_part_info_t info,
	const uint8_t *data, size_t size
	) {
	if (info->filename) {
	ant_value_t blob = blob_create(
	js, data, size, info->content_type
	? info->content_type : ""
	);

	if (is_err(blob)) return blob;

	return formdata_append_file(
	js, fd, js_mkstr(js, info->name, strlen(info->name)),
	blob, js_mkstr(js, info->filename, strlen(info->filename))
	);
	}

	return formdata_append_string(
	js, fd,
	js_mkstr(js, info->name, strlen(info->name)),
	js_mkstr(js, data, size)
	);
	}

	static ant_value_t parse_formdata_multipart(
	ant_t js, const uint8_t data, size_t size, const char *body_type
	) {
	ant_value_t fd = 0;
	char *boundary = NULL;
	char *delim = NULL;

	const uint8_t *p = data;
	const uint8_t *end = data + size;
	size_t delim_len = 0;

	if (!data \|\| size == 0) return multipart_invalid(js);
	boundary = ct_get_param_dup(body_type, "boundary");
	if (!boundary \|\| boundary[0] == '\0') goto invalid;

	fd = formdata_create_empty(js);
	if (is_err(fd)) goto done;

	delim_len = strlen(boundary) + 2;
	delim = malloc(delim_len + 1);
	if (!delim) {
	fd = js_mkerr(js, "out of memory");
	goto done;
	}
	snprintf(delim, delim_len + 1, "--%s", boundary);

	if ((size_t)(end - p) < delim_len \|\| memcmp(p, delim, delim_len) != 0) goto invalid;
	p += delim_len;

	next_part:
	if (p > end) goto done;
	if ((size_t)(end - p) >= 2 && memcmp(p, "--", 2) == 0) goto done;
	if ((size_t)(end - p) < 2 \|\| memcmp(p, "\r\n", 2) != 0) goto invalid;
	p += 2;

	{
	ant_value_t r = 0;
	ant_value_t hdr_err = js_mkundef();
	const uint8_t *hdr_end = find_bytes(
	p, (size_t)(end - p), (const uint8_t *)"\r\n\r\n", 4
	);

	char *headers = NULL;
	multipart_part_info_t info = {0};
	const uint8_t *part_end = NULL;

	if (!hdr_end) goto invalid;

	headers = strndup((const char *)p, (size_t)(hdr_end - p));
	if (!headers) {
	fd = js_mkerr(js, "out of memory");
	goto done;
	}
	p = hdr_end + 4;

	if (!multipart_parse_headers(js, headers, &info, &hdr_err)) {
	free(headers);
	multipart_part_info_clear(&info);
	if (is_err(hdr_err)) { fd = hdr_err; goto done; }
	goto invalid;
	}
	free(headers);

	part_end = multipart_find_part_end(p, end, delim, delim_len);
	if (!part_end) {
	multipart_part_info_clear(&info);
	goto invalid;
	}

	r = multipart_append_part(js, fd, &info, p, (size_t)(part_end - p));
	multipart_part_info_clear(&info);
	if (is_err(r)) { fd = r; goto done; }

	p = part_end + 2 + delim_len;
	if ((size_t)(end - p) >= 2 && memcmp(p, "--", 2) == 0) goto done;
	}

	goto next_part;

	invalid:
	fd = multipart_invalid(js);

	done:
	free(boundary);
	free(delim);
	return fd;
	}

	ant_value_t formdata_parse_body(
	ant_t js, const uint8_t data, size_t size,
	const char *body_type, bool has_body
	) {
	if (body_type && ct_is_type(body_type, "application/x-www-form-urlencoded")) {
	return parse_formdata_urlencoded(js, data, size);
	}

	if (body_type && ct_is_type(body_type, "multipart/form-data")) {
	if (!has_body \|\| !data \|\| size == 0) return js_mkerr_typed(js, JS_ERR_TYPE, "Failed to parse body as FormData");
	return parse_formdata_multipart(js, data, size, body_type);
	}

	return js_mkerr_typed(js, JS_ERR_TYPE, "Failed to parse body as FormData");
	}

	typedef struct {
	uint8_t *buf;
	size_t size;
	size_t cap;
	} mp_buf_t;

	static bool mp_grow(mp_buf_t *b, size_t need) {
	size_t nc = 0;
	uint8_t *nb = NULL;

	if (b->size + need <= b->cap) return true;

	nc = b->cap ? b->cap * 2 : 4096;
	while (nc < b->size + need) nc *= 2;

	nb = realloc(b->buf, nc);
	if (!nb) return false;
	b->buf = nb;
	b->cap = nc;
	return true;
	}

	static bool mp_append(mp_buf_t b, const void data, size_t len) {
	if (!mp_grow(b, len)) return false;
	memcpy(b->buf + b->size, data, len);
	b->size += len;
	return true;
	}

	static bool mp_append_str(mp_buf_t b, const char s) {
	return mp_append(b, s, strlen(s));
	}

	static bool mp_append_quoted(mp_buf_t b, const char s) {
	const char *p = s ? s : "";
	if (!mp_append_str(b, "\"")) return false;

	while (*p) {
	if (p == '"' \|\| p == '\\') if (!mp_append(b, "\\", 1)) return false;
	if (!mp_append(b, p, 1)) return false;
	p++;
	}

	return mp_append_str(b, "\"");
	}

	static bool mp_append_boundary(mp_buf_t b, const char boundary, bool closing) {
	if (!mp_append_str(b, "--")) return false;
	if (!mp_append_str(b, boundary)) return false;
	return mp_append_str(b, closing ? "--\r\n" : "\r\n");
	}

	static bool mp_append_text_part(mp_buf_t b, const fd_entry_t e) {
	const char *val = e->str_value ? e->str_value : "";

	if (!mp_append_str(b, "Content-Disposition: form-data; name=")) return false;
	if (!mp_append_quoted(b, e->name ? e->name : "")) return false;
	if (!mp_append_str(b, "\r\n\r\n")) return false;

	return mp_append_str(b, val);
	}

	static bool mp_append_file_part(ant_t js, mp_buf_t b, ant_value_t values_arr, const fd_entry_t *e) {
	ant_value_t file_val = js_arr_get(js, values_arr, (ant_offset_t)e->val_idx);
	blob_data_t *bd = blob_get_data(file_val);

	const char *filename = (bd && bd->name) ? bd->name : "blob";
	const char *mime = (bd && bd->type && bd->type[0])
	? bd->type
	: "application/octet-stream";

	if (!mp_append_str(b, "Content-Disposition: form-data; name=")) return false;
	if (!mp_append_quoted(b, e->name ? e->name : "")) return false;
	if (!mp_append_str(b, "; filename=")) return false;
	if (!mp_append_quoted(b, filename)) return false;
	if (!mp_append_str(b, "\r\nContent-Type: ")) return false;
	if (!mp_append_str(b, mime)) return false;
	if (!mp_append_str(b, "\r\n\r\n")) return false;
	if (!bd \|\| !bd->data \|\| bd->size == 0) return true;

	return mp_append(b, bd->data, bd->size);
	}

	uint8_t *formdata_serialize_multipart(
	ant_t js, ant_value_t fd, size_t out_size, char **out_boundary
	) {
	ant_value_t values_arr = js_get_slot(fd, SLOT_ENTRIES);
	ant_value_t data_slot = js_get_slot(fd, SLOT_DATA);
	char boundary[49];

	mp_buf_t b = {NULL, 0, 0};
	fd_data_t *d = NULL;

	if (vtype(data_slot) != T_NUM) return NULL;
	d = (fd_data_t *)(uintptr_t)(size_t)js_getnum(data_slot);
	if (!d) return NULL;

	snprintf(
	boundary, sizeof(boundary),
	"----AntFormBoundary%08x%08x", (unsigned)rand(), (unsigned)rand()
	);

	if (d->count == 0) {
	uint8_t *empty = malloc(1);
	if (!empty) return NULL;

	*out_size = 0;
	*out_boundary = strdup(boundary);

	if (!*out_boundary) {
	free(empty);
	return NULL;
	}

	return empty;
	}

	for (fd_entry_t *e = d->head; e; e = e->next) {
	if (!mp_append_boundary(&b, boundary, false)) goto oom;
	if (!e->is_file && !mp_append_text_part(&b, e)) goto oom;
	if (e->is_file && !mp_append_file_part(js, &b, values_arr, e)) goto oom;
	if (!mp_append_str(&b, "\r\n")) goto oom;
	}

	if (!mp_append_boundary(&b, boundary, true)) goto oom;

	*out_size = b.size;
	*out_boundary = strdup(boundary);

	if (!*out_boundary) goto oom;
	return b.buf;

	oom:
	free(b.buf);
	return NULL;
	}

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