avformat/ip: factorize some IP filtering and resolving functions to a new file

These are based on the very similar UDP and RTP protocol functions.
Signed-off-by: Marton Balint <cus@passwd.hu>

libavformat/ip.c

+/*
+ * IP common code
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public License
+ * as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with FFmpeg; if not, write to the Free Software * Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "ip.h"
+#include "libavutil/avstring.h"
+
+static int compare_addr(const struct sockaddr_storage *a,
+                        const struct sockaddr_storage *b)
+{
+    if (a->ss_family != b->ss_family)
+        return 1;
+    if (a->ss_family == AF_INET) {
+        return (((const struct sockaddr_in *)a)->sin_addr.s_addr !=
+                ((const struct sockaddr_in *)b)->sin_addr.s_addr);
+    }
+
+#if HAVE_STRUCT_SOCKADDR_IN6
+    if (a->ss_family == AF_INET6) {
+        const uint8_t *s6_addr_a = ((const struct sockaddr_in6 *)a)->sin6_addr.s6_addr;
+        const uint8_t *s6_addr_b = ((const struct sockaddr_in6 *)b)->sin6_addr.s6_addr;
+        return memcmp(s6_addr_a, s6_addr_b, 16);
+    }
+#endif
+    return 1;
+}
+
+int ff_ip_check_source_lists(struct sockaddr_storage *source_addr_ptr, IPSourceFilters *s)
+{
+    int i;
+    if (s->nb_exclude_addrs) {
+        for (i = 0; i < s->nb_exclude_addrs; i++) {
+            if (!compare_addr(source_addr_ptr, &s->exclude_addrs[i]))
+                return 1;
+        }
+    }
+    if (s->nb_include_addrs) {
+        for (i = 0; i < s->nb_include_addrs; i++) {
+            if (!compare_addr(source_addr_ptr, &s->include_addrs[i]))
+                return 0;
+        }
+        return 1;
+    }
+    return 0;
+}
+
+struct addrinfo *ff_ip_resolve_host(void *log_ctx,
+                                    const char *hostname, int port,
+                                    int type, int family, int flags)
+{
+    struct addrinfo hints = { 0 }, *res = 0;
+    int error;
+    char sport[16];
+    const char *node = 0, *service = "0";
+
+    if (port > 0) {
+        snprintf(sport, sizeof(sport), "%d", port);
+        service = sport;
+    }
+    if ((hostname) && (hostname[0] != '\0') && (hostname[0] != '?')) {
+        node = hostname;
+    }
+    hints.ai_socktype = type;
+    hints.ai_family   = family;
+    hints.ai_flags    = flags;
+    if ((error = getaddrinfo(node, service, &hints, &res))) {
+        res = NULL;
+        av_log(log_ctx, AV_LOG_ERROR, "getaddrinfo(%s, %s): %s\n",
+               node ? node : "unknown",
+               service,
+               gai_strerror(error));
+    }
+
+    return res;
+}
+
+
+static int ip_parse_addr_list(void *log_ctx, const char *buf,
+                              struct sockaddr_storage **address_list_ptr,
+                              int *address_list_size_ptr)
+{
+    struct addrinfo *ai = NULL;
+
+    /* Resolve all of the IPs */
+
+    while (buf && buf[0]) {
+        char* host = av_get_token(&buf, ",");
+        if (!host)
+            return AVERROR(ENOMEM);
+
+        ai = ff_ip_resolve_host(log_ctx, host, 0, SOCK_DGRAM, AF_UNSPEC, 0);
+        av_freep(&host);
+
+        if (ai) {
+            struct sockaddr_storage source_addr = {0};
+            memcpy(&source_addr, ai->ai_addr, ai->ai_addrlen);
+            freeaddrinfo(ai);
+            av_dynarray2_add((void **)address_list_ptr, address_list_size_ptr, sizeof(source_addr), (uint8_t *)&source_addr);
+            if (!*address_list_ptr)
+                return AVERROR(ENOMEM);
+        } else {
+            return AVERROR(EINVAL);
+        }
+
+        if (*buf)
+            buf++;
+    }
+
+    return 0;
+}
+
+static int ip_parse_sources_and_blocks(void *log_ctx, const char *buf, IPSourceFilters *filters, int parse_include_list)
+{
+    int ret;
+    if (parse_include_list)
+        ret = ip_parse_addr_list(log_ctx, buf, &filters->include_addrs, &filters->nb_include_addrs);
+    else
+        ret = ip_parse_addr_list(log_ctx, buf, &filters->exclude_addrs, &filters->nb_exclude_addrs);
+
+    if (ret >= 0 && filters->nb_include_addrs && filters->nb_exclude_addrs) {
+        av_log(log_ctx, AV_LOG_ERROR, "Simultaneously including and excluding sources is not supported.\n");
+        return AVERROR(EINVAL);
+    }
+    return ret;
+}
+
+int ff_ip_parse_sources(void *log_ctx, const char *buf, IPSourceFilters *filters)
+{
+    return ip_parse_sources_and_blocks(log_ctx, buf, filters, 1);
+}
+
+int ff_ip_parse_blocks(void *log_ctx, const char *buf, IPSourceFilters *filters)
+{
+    return ip_parse_sources_and_blocks(log_ctx, buf, filters, 0);
+}
+
+void ff_ip_reset_filters(IPSourceFilters *filters)
+{
+    av_freep(&filters->exclude_addrs);
+    av_freep(&filters->include_addrs);
+    filters->nb_include_addrs = 0;
+    filters->nb_exclude_addrs = 0;
+}

libavformat/ip.h

+/*
+ * IP common code
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public License
+ * as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with FFmpeg; if not, write to the Free Software * Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef AVFORMAT_IP_H
+#define AVFORMAT_IP_H
+
+#include "network.h"
+
+/**
+ * Structure for storing IP (UDP) source filters or block lists.
+ */
+typedef struct IPSourceFilters {
+    int nb_include_addrs;
+    int nb_exclude_addrs;
+    struct sockaddr_storage *include_addrs;
+    struct sockaddr_storage *exclude_addrs;
+} IPSourceFilters;
+
+/**
+ * Checks the source address against a given IP source filter.
+ * @return 0 if packet should be processed based on the filter, 1 if the packet
+ *         can be dropped.
+ */
+int ff_ip_check_source_lists(struct sockaddr_storage *source_addr_ptr, IPSourceFilters *s);
+
+/**
+ * Resolves hostname into an addrinfo structure.
+ * @return addrinfo structure which should be freed by the user, NULL in case
+ *         of error.
+ */
+struct addrinfo *ff_ip_resolve_host(void *log_ctx,
+                                    const char *hostname, int port,
+                                    int type, int family, int flags);
+
+/**
+ * Parses the address[,address] source list in buf and adds it to the filters
+ * in the IPSourceFilters structure.
+ * @return 0 on success, < 0 AVERROR code on error.
+ */
+int ff_ip_parse_sources(void *log_ctx, const char *buf, IPSourceFilters *filters);
+
+/**
+ * Parses the address[,address] source block list in buf and adds it to the
+ * filters in the IPSourceFilters structure.
+ * @return 0 on success, < 0 AVERROR code on error.
+ */
+int ff_ip_parse_blocks(void *log_ctx, const char *buf, IPSourceFilters *filters);
+
+/**
+ * Resets the IP filter list and frees the internal fields of an
+ * IPSourceFilters structure.
+ */
+void ff_ip_reset_filters(IPSourceFilters *filters);
+
+#endif /* AVFORMAT_IP_H */