{"record":{"id":"897522d9e0f11ba2","repo":"lionsoul2014/ip2region","slug":"ip2region-search-failed-for-ipv4-address","errorCode":null,"errorMessage":"ip2region search failed for IPv4 address","messagePattern":"ip2region search failed for IPv4 address","errorType":"console","errorClass":null,"httpStatus":null,"severity":"warning","filePath":"binding/nginx/src/ngx_http_ip2region_module.c","lineNumber":404,"sourceCode":"\n            // 正确转换IP地址字节序，按ip2region期望的格式\n            ip = ntohl(sin->sin_addr.s_addr); // 将网络字节序转换为主机字节序\n            // 按照xdb_parse_v4_ip中的格式重新组织字节\n            {\n                bytes_ip_t ip_bytes[4];\n                ip_bytes[0] = (ip >> 24) & 0xFF;\n                ip_bytes[1] = (ip >> 16) & 0xFF;\n                ip_bytes[2] = (ip >> 8) & 0xFF;\n                ip_bytes[3] = ip & 0xFF;\n                err = xdb_search(searcher_ptr, ip_bytes, 4, &region);\n            }\n            if (err == 0) {\n                v->data = (unsigned char *)region.value;\n                v->len = strlen(region.value);\n                xdb_region_buffer_free(&region);\n                return NGX_OK;\n            } else {\n                ngx_log_error(NGX_LOG_WARN, r->connection->log, 0,\n                              \"ip2region search failed for IPv4 address\");\n            }\n            break;\n\n#if (NGX_HAVE_INET6)\n\n        case AF_INET6:\n            sin6 = (struct sockaddr_in6 *) r->connection->sockaddr;\n            p = sin6->sin6_addr.s6_addr;\n\n            if (IN6_IS_ADDR_V4MAPPED(&sin6->sin6_addr)) {\n                // 处理IPv4映射的IPv6地址\n                if (ip2region_conf->v4_searcher != NULL) {\n                    searcher_ptr = &ip2region_conf->v4_searcher->searcher;\n                    addr = p[12] << 24;\n                    addr += p[13] << 16;\n                    addr += p[14] << 8;\n                    addr += p[15];","sourceCodeStart":386,"sourceCodeEnd":422,"githubUrl":"https://github.com/lionsoul2014/ip2region/blob/c1a1fc7d5941760db3f8431dc05c48cf7f0e30a1/binding/nginx/src/ngx_http_ip2region_module.c#L386-L422","documentation":"The IPv4 searcher exists and xdb_search_by_string was called with the client IP, but it returned a non-zero error, so no region string could be produced. The variable is left empty and a warning is logged per failing request. This indicates the lookup itself failed against the loaded database (not a config abort).","triggerScenarios":"xdb_search_by_string returns err != 0 for the given IPv4 string: malformed/unexpected IP input reaching the searcher, an invalid or mismatched searcher/db state (e.g. db reloaded or corrupt), or internal search failure (bad index offsets).","commonSituations":"Requests from odd addresses (e.g. 0.0.0.0 or unix-socket-derived values coerced into IPv4 form); truncated or corrupted xdb loaded at startup; using an xdb version not matching the module build so offsets resolve incorrectly.","solutions":["Verify the loaded xdb is complete and matches the module's expected version; re-download it.","Test the same IP against the xdb with the official xdb CLI/binding (`search` tool) to see if the DB itself errors.","Check which client IPs trigger it — malformed or proxy-injected addresses may need real_ip handling ($realip_remote_addr).","If the searcher state is suspect, restart nginx to rebuild searchers from the current file.","Ensure the module and xdb data are from compatible ip2region versions."],"exampleFix":"# before (possibly proxy-supplied bogus address)\nlog_format main '$ip2region ...';\n# after (search on the original client address)\nlog_format main '$realip_remote_addr=$ip2region ...';\nreal_ip_header X-Forwarded-For;","handlingStrategy":"try-catch","validationCode":"# verify the DB can resolve a known IP using the official CLI before trusting it in nginx\nxdb search --db=/data/ip2region.xdb --ip=1.2.3.4 || echo \"xdb itself fails on known IP -> reload or replace the db\"","typeGuard":null,"tryCatchPattern":"# nginx.conf: give the lookup variable a fallback via map\nmap $ip2region $ip2region_or_unknown {\n    \"\"      \"unknown\";   # covers search failures and empty results\n    default $ip2region;\n}\nlog_format main '$remote_addr region=$ip2region_or_unknown';","preventionTips":["Alert on WARN 'ip2region search failed' frequency in nginx error logs.","Replace the xdb by atomic rename + reload if failures spike.","Handle proxied clients with real_ip so searches run on real client IPs.","Keep module and xdb data versions in lockstep."],"tags":["nginx","runtime","search-failure","ipv4","xdb"],"backgroundTag":"xdb-search-failed","analyzedSha":"c1a1fc7d5941760db3f8431dc05c48cf7f0e30a1","analyzedAt":"2026-09-02T16:58:39.988Z","contentChangedAt":null,"schemaVersion":2},"datasetVersion":"2026-09-09T21:17:11.164Z"}