From 7b9920aad80299d79f4dba08de36693804f8751c Mon Sep 17 00:00:00 2001 From: Maxim Dounin Date: Wed, 21 Apr 2021 23:24:59 +0300 Subject: [PATCH] Mail: fixed reading with fully filled buffer (ticket #2159). With SMTP pipelining, ngx_mail_read_command() can be called with s->buffer without any space available, to parse additional commands received to the buffer on previous calls. Previously, this resulted in recv() being called with zero length, resulting in zero being returned, which was interpreted as a connection close by the client, so nginx silently closed connection. Fix is to avoid calling c->recv() if there is no free space in the buffer, but continue parsing of the already received commands. --- src/mail/ngx_mail_handler.c | 25 ++++++++++++++----------- 1 file changed, 14 insertions(+), 11 deletions(-) diff --git a/src/mail/ngx_mail_handler.c b/src/mail/ngx_mail_handler.c index 0aaa0e786..57503e9a6 100644 --- a/src/mail/ngx_mail_handler.c +++ b/src/mail/ngx_mail_handler.c @@ -833,20 +833,23 @@ ngx_mail_read_command(ngx_mail_session_t *s, ngx_connection_t *c) ngx_str_t l; ngx_mail_core_srv_conf_t *cscf; - n = c->recv(c, s->buffer->last, s->buffer->end - s->buffer->last); + if (s->buffer->last < s->buffer->end) { - if (n == NGX_ERROR || n == 0) { - ngx_mail_close_connection(c); - return NGX_ERROR; - } + n = c->recv(c, s->buffer->last, s->buffer->end - s->buffer->last); - if (n > 0) { - s->buffer->last += n; - } + if (n == NGX_ERROR || n == 0) { + ngx_mail_close_connection(c); + return NGX_ERROR; + } - if (n == NGX_AGAIN) { - if (s->buffer->pos == s->buffer->last) { - return NGX_AGAIN; + if (n > 0) { + s->buffer->last += n; + } + + if (n == NGX_AGAIN) { + if (s->buffer->pos == s->buffer->last) { + return NGX_AGAIN; + } } }