使用curl时如何设置HTTP/2伪标头？

尝试用curl发送请求时添加HTTP/2伪标头，执行命令：

curl -v -H ":test: value" https://example.com

以及其他以冒号开头的标头名称，均报错：

curl: (55) Failed sending HTTP request

完整的curl详细输出：

*   Trying 93.184.216.34:443...
* Connected to example.com (93.184.216.34) port 443 (#0)
* ALPN, offering h2
* ALPN, offering http/1.1
*  CAfile: /etc/ssl/certs/ca-certificates.crt
*  CApath: /etc/ssl/certs
* TLSv1.0 (OUT), TLS header, Certificate Status (22):
* TLSv1.3 (OUT), TLS handshake, Client hello (1):
* TLSv1.2 (IN), TLS header, Certificate Status (22):
* TLSv1.3 (IN), TLS handshake, Server hello (2):
* TLSv1.2 (OUT), TLS header, Finished (20):
* TLSv1.3 (OUT), TLS change cipher, Change cipher spec (1):
* TLSv1.2 (OUT), TLS header, Certificate Status (22):
* TLSv1.3 (OUT), TLS handshake, Client hello (1):
* TLSv1.2 (IN), TLS header, Finished (20):
* TLSv1.2 (IN), TLS header, Certificate Status (22):
* TLSv1.3 (IN), TLS handshake, Server hello (2):
* TLSv1.2 (IN), TLS header, Supplemental data (23):
* TLSv1.3 (IN), TLS handshake, Encrypted Extensions (8):
* TLSv1.2 (IN), TLS header, Supplemental data (23):
* TLSv1.3 (IN), TLS handshake, Certificate (11):
* TLSv1.2 (IN), TLS header, Supplemental data (23):
* TLSv1.3 (IN), TLS handshake, CERT verify (15):
* TLSv1.2 (IN), TLS header, Supplemental data (23):
* TLSv1.3 (IN), TLS handshake, Finished (20):
* TLSv1.2 (OUT), TLS header, Supplemental data (23):
* TLSv1.3 (OUT), TLS handshake, Finished (20):
* SSL connection using TLSv1.3 / TLS_AES_256_GCM_SHA384
* ALPN, server accepted to use h2
* Server certificate:
*  subject: C=US; ST=California; L=Los Angeles; O=Internet�Corporation�for�Assigned�Names�and�Numbers; CN=www.example.org
*  start date: Jan 13 00:00:00 2023 GMT
*  expire date: Feb 13 23:59:59 2024 GMT
*  subjectAltName: host "example.com" matched cert's "example.com"
*  issuer: C=US; O=DigiCert Inc; CN=DigiCert TLS RSA SHA256 2020 CA1
*  SSL certificate verify ok.
* Using HTTP2, server supports multiplexing
* Connection state changed (HTTP/2 confirmed)
* Copying HTTP/2 data in stream buffer to connection buffer after upgrade: len=0
* TLSv1.2 (OUT), TLS header, Supplemental data (23):
* TLSv1.2 (OUT), TLS header, Supplemental data (23):
* TLSv1.2 (OUT), TLS header, Supplemental data (23):
* Failed sending HTTP request
* Connection #0 to host example.com left intact
curl: (55) Failed sending HTTP request

curl不允许用户自定义HTTP/2伪标头，核心原因如下：

• HTTP/2的伪标头（如:method、:path、:authority、:scheme）是协议规定的专用标头，由curl自动生成和管理，用户无法通过-H选项添加自定义的伪标头（即以冒号开头的自定义标头名称）。
• 当尝试发送自定义伪标头时，curl会判定这类请求不符合协议规范，直接终止发送流程，触发(55) Failed sending HTTP request错误。

如果需要调整HTTP/2的标准伪标头，可通过curl的专用参数实现：

• 修改:path：直接在URL中指定目标路径，或使用--request-target参数
• 修改:method：使用-X或--request参数指定请求方法
• 修改:authority：通过--header "Host: 目标域名"设置，curl会自动将其映射为HTTP/2的:authority伪标头

内容的提问来源于stack exchange，提问作者Mustafa