05 proxy_pass 携带有 uri 的场景下面的处理

前言

这里主要是关注 proxy_pass 的配置, 对于 代理都上游服务的请求的相关处理的实现差异 

比如 如下配置是否存在什么差异, 造成的结果是什么 

        location ^~ /api/ {
               root html; 
               index  index.html index.htm;
               proxy_pass http://localhost:8080/api/;
        }

        location ^~ /api/ {
               root html; 
               index  index.html index.htm;
               proxy_pass http://localhost:8080/api;
        }

现在假设存在一个上游服务 http://localhost:8080/api/HelloWorld/listFormWithoutHeader?param01=p01¶m02=p02

上面的配置是可以正常代理的, 但是 下面的配置响应的是 404 

本文探讨的就是类似的问题 

以下截图, 调试基于 nginx-1.18.0

proxy_pass http://localhost:8080/api/ 的场景

这里首先是从 proxy_pass 中获取是否有 uri 参数, 这里为 "/api/" 

然后获取到的 loc_len 为 匹配到的 location 的字符串的长度, 这里为 "/api/" 长度为 5 

然后 下面是拼接 ctx.vars.uri 和 请求路径截取掉 location 匹配的字符串, "/api/" + "HelloWorld/listFormWithoutHeader", 最终得到路径 "/api/HelloWorld/listFormWithoutHeader"

Breakpoint 9, ngx_http_proxy_create_request (r=0x7f8b34801c50)
    at src/http/modules/ngx_http_proxy_module.c:1207
1207	    if (plcf->proxy_lengths && ctx->vars.uri.len) {
(gdb) print ctx->vars
$40 = {key_start = {len = 21, 
    data = 0x7f8b33808f5b "http://localhost:8080/api/"}, schema = {len = 7, 
    data = 0x7f8b33808f5b "http://localhost:8080/api/"}, host_header = {
    len = 14, data = 0x7f8b33808f62 "localhost:8080/api/"}, port = {len = 4, 
    data = 0x7f8b33808f6c "8080/api/"}, uri = {len = 5, 
    data = 0x7f8b33808f70 "/api/"}}
(gdb) next
1215	        loc_len = (r->valid_location && ctx->vars.uri.len) ?
(gdb) next
1216	                      plcf->location.len : 0;
(gdb) next
1215	        loc_len = (r->valid_location && ctx->vars.uri.len) ?
(gdb) next
1218	        if (r->quoted_uri || r->space_in_uri || r->internal) {
(gdb) print loc_len 
$41 = 5
(gdb) c
Continuing.
 
Breakpoint 10, ngx_http_proxy_create_request (r=0x7f8b34801c50)
    at src/http/modules/ngx_http_proxy_module.c:1332
1332	    if (plcf->proxy_lengths && ctx->vars.uri.len) {
(gdb) next
1339	        if (r->valid_location) {
(gdb) next
1340	            b->last = ngx_copy(b->last, ctx->vars.uri.data, ctx->vars.uri.len);
(gdb) next
1343	        if (escape) {
(gdb) next
1349	            b->last = ngx_copy(b->last, r->uri.data + loc_len,
(gdb) print r->uri 
$42 = {len = 37, 
  data = 0x7f8b34801804 "/api/HelloWorld/listFormWithoutHeader?param01=p01¶m02=p02 HTTP/1.1\r\nHost"}
(gdb) print loc_len
$43 = 5
(gdb) print b->start 
$44 = (u_char *) 0x7f8b34803408 "GET /api/"
(gdb) next
1353	        if (r->args.len > 0) {
(gdb) print b->start 
$45 = (u_char *) 0x7f8b34803408 "GET /api/HelloWorld/listFormWithoutHeader"
(gdb) next
1354	            *b->last++ = '?';
(gdb) next
1355	            b->last = ngx_copy(b->last, r->args.data, r->args.len);
(gdb) next
1359	    u->uri.len = b->last - u->uri.data;
(gdb) print b->start 
$46 = (u_char *) 0x7f8b34803408 "GET /api/HelloWorld/listFormWithoutHeader?param01=p01¶m02=p02"

proxy_pass http://localhost:8080/api 的场景

同样的道理 

这里首先是从 proxy_pass 中获取是否有 uri 参数, 这里为 "/api" 

然后获取到的 loc_len 为 匹配到的 location 的字符串的长度, 这里为 "/api/" 长度为 5 

然后 下面是拼接 ctx.vars.uri 和 请求路径截取掉 location 匹配的字符串, "/api" + "HelloWorld/listFormWithoutHeader", 最终得到路径 "/apiHelloWorld/listFormWithoutHeader"

然后 在上游服务那边, 找不到对应的服务, 因此 响应的是 404 

Breakpoint 9, ngx_http_proxy_create_request (r=0x7fdbf9000450)
    at src/http/modules/ngx_http_proxy_module.c:1207
1207	    if (plcf->proxy_lengths && ctx->vars.uri.len) {
(gdb) print ctx.vars
$47 = {key_start = {len = 21, 
    data = 0x7fdbf701eb5b "http://localhost:8080/api"}, schema = {len = 7, 
    data = 0x7fdbf701eb5b "http://localhost:8080/api"}, host_header = {
    len = 14, data = 0x7fdbf701eb62 "localhost:8080/api"}, port = {len = 4, 
    data = 0x7fdbf701eb6c "8080/api"}, uri = {len = 4, 
    data = 0x7fdbf701eb70 "/api"}}
(gdb) next
1215	        loc_len = (r->valid_location && ctx->vars.uri.len) ?
(gdb) next
1216	                      plcf->location.len : 0;
(gdb) next
1215	        loc_len = (r->valid_location && ctx->vars.uri.len) ?
(gdb) next
1218	        if (r->quoted_uri || r->space_in_uri || r->internal) {
(gdb) print loc_len
$48 = 5
(gdb) c
Continuing.
 
Breakpoint 10, ngx_http_proxy_create_request (r=0x7fdbf9000450)
    at src/http/modules/ngx_http_proxy_module.c:1332
1332	    if (plcf->proxy_lengths && ctx->vars.uri.len) {
(gdb) next
1339	        if (r->valid_location) {
(gdb) next
1340	            b->last = ngx_copy(b->last, ctx->vars.uri.data, ctx->vars.uri.len);
(gdb) next
1343	        if (escape) {
(gdb) print b->start
$49 = (u_char *) 0x7fdbf9001c08 "GET /api"
(gdb) next
1349	            b->last = ngx_copy(b->last, r->uri.data + loc_len,
(gdb) next
1353	        if (r->args.len > 0) {
(gdb) print b->start
$50 = (u_char *) 0x7fdbf9001c08 "GET /apiHelloWorld/listFormWithoutHeader"
(gdb) next
1354	            *b->last++ = '?';
(gdb) next
1355	            b->last = ngx_copy(b->last, r->args.data, r->args.len);
(gdb) next
1359	    u->uri.len = b->last - u->uri.data;
(gdb) print b->start
$51 = (u_char *) 0x7fdbf9001c08 "GET /apiHelloWorld/listFormWithoutHeader?param01=p01¶m02=p02"

结论

综合一下结论 

在 proxy_pass 存在 uri 部分的场景下面 

最终向上游服务器请求的路径是 ctx.uri + url中截取掉location之后的子串  

和三个部分是有关系的, 一个是 proxy_pass 影响的是 ctx.uri 

一个是请求的 url, 一个是 location 本身 

完