Minor fixes

[danielinux]

Address several improvements suggested by the static analysis tools.

F-242 - Fixes for non-ethernet builds
F-243 - ICMP: don't clear readable flag if fifo not empty
F-74 - fix potential buffer overflow in wolfIP_print_udp
F-138 - fix arguments check in wolfIP_sock_getpeer
F-140 - fix token serializations in dns_send_query

[Copilot]

Pull request overview

This PR addresses a set of static-analysis findings across wolfIP, primarily targeting safer length handling, non-Ethernet build compatibility, socket API argument validation, and more robust DNS query name serialization.

Changes:

• Harden UDP debug printing against short/invalid UDP lengths and add a regression unit test.
• Fix ICMP readable-event clearing logic to avoid clearing when the RX FIFO still has queued packets (with unit test).
• Improve non-Ethernet build compatibility by removing/guarding Ethernet-only assumptions and adding a compilation-only unit-noeth target.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/wolfip_debug.c	Adds a length guard to prevent UDP payload underflow/OOB reads when printing debug info.
src/wolfip.c	Fixes Ethernet header sizing assumptions, ICMP readable event handling, getpeername arg validation, Ethernet guards in ICMP reply path, and strengthens DNS label/name length checks.
src/test/unit/unit_noeth.c	Adds a compilation-only harness to ensure the stack builds with ETHERNET disabled.
src/test/unit/unit.c	Adds unit tests for the new error paths/edge cases; also toggles UDP debug compilation flags.
Makefile	Adds a unit-noeth target to compile the non-Ethernet harness.

Comments suppressed due to low confidence (2)

src/wolfip.c:5744

• The DNS QNAME length checks don’t reserve space for the terminating 0 byte. As written, a name can pass tok_len + label_len + 1 > MAX_DNS_NAME_LEN, reach tok_len == MAX_DNS_NAME_LEN, and then tok_len++ will make the encoded name length 256 bytes, exceeding the 255-byte DNS maximum and shifting q past the intended bounds. Update the bounds checks to account for the final terminator (e.g., ensure tok_len + label_len + 2 <= MAX_DNS_NAME_LEN, or add a check before incrementing/writing the terminator).

    if (strlen(dname) > MAX_DNS_NAME_LEN) return -22; /* Invalid arguments */
    if (s->dns_server == 0) return -101; /* Network unreachable: No DNS server configured */
    if (s->dns_id != 0) return -16; /* DNS query already in progress */
    if (s->dns_udp_sd <= 0) {
        s->dns_udp_sd = wolfIP_sock_socket(s, AF_INET, IPSTACK_SOCK_DGRAM, WI_IPPROTO_UDP);
        if (s->dns_udp_sd < 0)
            return -1;
        wolfIP_register_callback(s, s->dns_udp_sd, dns_callback, s);
    }
    s->dns_id = wolfIP_getrandom();
    *id = s->dns_id;
    memset(buf, 0, 512);
    s->dns_query_type = (qtype == DNS_PTR) ? DNS_QUERY_TYPE_PTR : DNS_QUERY_TYPE_A;
    hdr = (struct dns_header *)buf;
    hdr->id = ee16(s->dns_id);
    hdr->flags = ee16(DNS_QUERY);
    hdr->qdcount = ee16(1);
    hdr->flags = ee16(DNS_RD);
    /* Prepare the DNS query name */
    q_name = (char *)(buf + sizeof(struct dns_header));
    tok_start = (char *)dname;
    while(*tok_start) {
        tok_end = tok_start;
        while ((*tok_end != '.') && (*tok_end != 0)) {
            tok_end++;
        }
        label_len = (uint32_t)(tok_end - tok_start);
        if (label_len > MAX_DNS_LABEL_LEN) return -22;
        if (tok_len + label_len + 1 > MAX_DNS_NAME_LEN) return -22;
        *q_name = (char)label_len;
        q_name++;
        memcpy(q_name, tok_start, label_len);
        q_name += label_len;
        tok_len += label_len + 1;
        if (*tok_end == 0)
            break;
        tok_start = tok_end + 1;
    }
    *q_name = 0;
    tok_len++;
    q = (struct dns_question *)(buf + sizeof(struct dns_header) + tok_len);
    q->qtype = ee16(qtype);

src/wolfip_debug.c:98

• Within wolfIP_print_udp, payload_str is zeroed twice (once before the block and again inside it), and the payload length calculation still uses the magic constant 8 instead of UDP_HEADER_LEN. Removing the redundant memset and using UDP_HEADER_LEN would keep the debug helper simpler and less error-prone.

    memset(payload_str, '\0', sizeof(payload_str));
    {
        /* show first 16 printable chars of payload */
        uint16_t max_len = 16;
        size_t   i = 0;
        size_t   print_len = 0;
        if (len <= UDP_HEADER_LEN)
            return;
        print_len = (len - 8) < max_len ? (len  - 8): max_len;
        memset(payload_str, '\0', sizeof(payload_str));
        memcpy(payload_str, udp->data, print_len);

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[gasbytes]

lgtm, verified and reviewed locally with gh cli.