Re: [PATCH v5 10/29] udp: Convert to iov_tail

On Thu, 17 Apr 2025 18:51:17 +0200 Laurent Vivier wrote:

Use packet_data() and extract headers using IOV_REMOVE_HEADER() and IOV_PEEK_HEADER() rather than packet_get().

Signed-off-by: Laurent Vivier --- iov.c | 1 - udp.c | 34 +++++++++++++++++++++++----------- 2 files changed, 23 insertions(+), 12 deletions(-)

diff --git a/iov.c b/iov.c index bb095634246e..3e18040d22a8 100644 --- a/iov.c +++ b/iov.c @@ -389,7 +389,6 @@ void *iov_remove_header_(struct iov_tail *tail, void *v, size_t len, size_t alig * iov array, a negative value if there is not enough room in the * destination iov array */ -/* cppcheck-suppress unusedFunction */ int iov_tail_slice(struct iovec *dst_iov, size_t dst_iov_cnt, struct iov_tail *tail, size_t *bytes) { diff --git a/udp.c b/udp.c index 40af7dfc260f..27e31bc5d92d 100644 --- a/udp.c +++ b/udp.c @@ -872,15 +872,20 @@ int udp_tap_handler(const struct ctx *c, uint8_t pif, struct iovec m[UIO_MAXIOV]; const struct udphdr *uh; struct udp_flow *uflow; - int i, s, count = 0; + int i, j, s, count = 0; + struct iov_tail data; flow_sidx_t tosidx; in_port_t src, dst; + struct udphdr uhc;

I'm struggling to understand what the 'c' in 'uhc' stands for ("contiguous"?), but given that it's used just twice, what about making it a bit longer, say, 'uh_storage'?

uint8_t topif; socklen_t sl;

ASSERT(!c->no_udp);

- uh = packet_get(p, idx, 0, sizeof(*uh), NULL); + if (!packet_data(p, idx, &data)) + return 1; + + uh = IOV_PEEK_HEADER(&data, uhc); if (!uh) return 1;

@@ -917,23 +922,30 @@ int udp_tap_handler(const struct ctx *c, uint8_t pif,

pif_sockaddr(c, &to_sa, &sl, topif, &toside->eaddr, toside->eport);

- for (i = 0; i < (int)p->count - idx; i++) { - struct udphdr *uh_send; - size_t len; + for (i = 0, j = 0; i < (int)p->count - idx && j < UIO_MAXIOV; i++) { + const struct udphdr *uh_send;

- uh_send = packet_get(p, idx + i, 0, sizeof(*uh), &len); + if (!packet_data(p, idx + i, &data)) + return p->count - idx; + + uh_send = IOV_REMOVE_HEADER(&data, uhc); if (!uh_send) return p->count - idx;

mm[i].msg_hdr.msg_name = &to_sa; mm[i].msg_hdr.msg_namelen = sl;

- if (len) { - m[i].iov_base = (char *)(uh_send + 1); - m[i].iov_len = len; + if (data.cnt) { + int cnt; + + cnt = iov_tail_slice(&m[j], UIO_MAXIOV - j, + &data, NULL); + if (cnt < 0) + return p->count - idx;

- mm[i].msg_hdr.msg_iov = m + i; - mm[i].msg_hdr.msg_iovlen = 1; + mm[i].msg_hdr.msg_iov = &m[j]; + mm[i].msg_hdr.msg_iovlen = cnt; + j += cnt; } else { mm[i].msg_hdr.msg_iov = NULL; mm[i].msg_hdr.msg_iovlen = 0;

-- Stefano