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Sub filter: fixed matching after a partial match.

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After a failed partial match we now check if there is another partial
match in previously matched substring to fix cases like "aab" in "aaab".

The ctx->saved string is now always sent if it's present on return
from the ngx_http_sub_parse() function (and reset accordingly).  This
allows to release parts of previously matched data.
This commit is contained in:
Maxim Dounin 2013-07-25 14:54:53 +04:00
parent ce7a5a0537
commit 1936a67647
1 changed files with 75 additions and 37 deletions
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112
src/http/modules/ngx_http_sub_filter_module.c
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@ -261,37 +261,37 @@ ngx_http_sub_body_filter(ngx_http_request_t *r, ngx_chain_t *in)
return rc; return rc;
} }
if (ctx->copy_start != ctx->copy_end) { if (ctx->saved.len) {
ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
"saved: \"%V\"", &ctx->saved); "saved: \"%V\"", &ctx->saved);
if (ctx->saved.len) { cl = ngx_chain_get_free_buf(r->pool, &ctx->free);
if (cl == NULL) {
cl = ngx_chain_get_free_buf(r->pool, &ctx->free); return NGX_ERROR;
if (cl == NULL) {
return NGX_ERROR;
}
b = cl->buf;
ngx_memzero(b, sizeof(ngx_buf_t));
b->pos = ngx_pnalloc(r->pool, ctx->saved.len);
if (b->pos == NULL) {
return NGX_ERROR;
}
ngx_memcpy(b->pos, ctx->saved.data, ctx->saved.len);
b->last = b->pos + ctx->saved.len;
b->memory = 1;
*ctx->last_out = cl;
ctx->last_out = &cl->next;
ctx->saved.len = 0;
} }
b = cl->buf;
ngx_memzero(b, sizeof(ngx_buf_t));
b->pos = ngx_pnalloc(r->pool, ctx->saved.len);
if (b->pos == NULL) {
return NGX_ERROR;
}
ngx_memcpy(b->pos, ctx->saved.data, ctx->saved.len);
b->last = b->pos + ctx->saved.len;
b->memory = 1;
*ctx->last_out = cl;
ctx->last_out = &cl->next;
ctx->saved.len = 0;
}
if (ctx->copy_start != ctx->copy_end) {
cl = ngx_chain_get_free_buf(r->pool, &ctx->free); cl = ngx_chain_get_free_buf(r->pool, &ctx->free);
if (cl == NULL) { if (cl == NULL) {
return NGX_ERROR; return NGX_ERROR;
@ -325,6 +325,11 @@ ngx_http_sub_body_filter(ngx_http_request_t *r, ngx_chain_t *in)
ctx->copy_end = NULL; ctx->copy_end = NULL;
} }
if (ctx->looked.len > (size_t) (ctx->pos - ctx->buf->pos)) {
ctx->saved.len = ctx->looked.len - (ctx->pos - ctx->buf->pos);
ngx_memcpy(ctx->saved.data, ctx->looked.data, ctx->saved.len);
}
if (rc == NGX_AGAIN) { if (rc == NGX_AGAIN) {
continue; continue;
} }
@ -502,7 +507,7 @@ static ngx_int_t
ngx_http_sub_parse(ngx_http_request_t *r, ngx_http_sub_ctx_t *ctx) ngx_http_sub_parse(ngx_http_request_t *r, ngx_http_sub_ctx_t *ctx)
{ {
u_char *p, *last, *copy_end, ch, match; u_char *p, *last, *copy_end, ch, match;
size_t looked; size_t looked, i;
ngx_http_sub_state_e state; ngx_http_sub_state_e state;
if (ctx->once) { if (ctx->once) {
@ -573,13 +578,11 @@ ngx_http_sub_parse(ngx_http_request_t *r, ngx_http_sub_ctx_t *ctx)
looked++; looked++;
if (looked == ctx->match.len) { if (looked == ctx->match.len) {
if ((size_t) (p - ctx->pos) < looked) {
ctx->saved.len = 0;
}
ctx->state = sub_start_state; ctx->state = sub_start_state;
ctx->pos = p + 1; ctx->pos = p + 1;
ctx->looked.len = 0; ctx->looked.len = 0;
ctx->saved.len = 0;
ctx->copy_end = copy_end; ctx->copy_end = copy_end;
if (ctx->copy_start == NULL && copy_end) { if (ctx->copy_start == NULL && copy_end) {
@ -589,18 +592,53 @@ ngx_http_sub_parse(ngx_http_request_t *r, ngx_http_sub_ctx_t *ctx)
return NGX_OK; return NGX_OK;
} }
} else if (ch == ctx->match.data[0]) {
copy_end = p;
ctx->looked.data[0] = *p;
looked = 1;
} else { } else {
copy_end = p; /*
looked = 0; * check if there is another partial match in previously
state = sub_start_state; * matched substring to catch cases like "aab" in "aaab"
*/
ctx->looked.data[looked] = *p;
looked++;
for (i = 1; i < looked; i++) {
if (ngx_strncasecmp(ctx->looked.data + i,
ctx->match.data, looked - i)
== 0)
{
break;
}
}
if (i < looked) {
if (ctx->saved.len > i) {
ctx->saved.len = i;
}
if ((size_t) (p + 1 - ctx->buf->pos) >= looked - i) {
copy_end = p + 1 - (looked - i);
}
ngx_memmove(ctx->looked.data, ctx->looked.data + i, looked - i);
looked = looked - i;
} else {
copy_end = p;
looked = 0;
state = sub_start_state;
}
if (ctx->saved.len) {
p++;
goto out;
}
} }
} }
ctx->saved.len = 0;
out:
ctx->state = state; ctx->state = state;
ctx->pos = p; ctx->pos = p;
ctx->looked.len = looked; ctx->looked.len = looked;